[0001]The present invention relates to a grain oriented electrical steel sheet, a forming
10 method for an insulation coating of a grain oriented electrical steel sheet, and a producing
method for a grain oriented electrical steel sheet.
Priority is claimed on Japanese Patent Application No. 2019-021284, filed on
February 8, 2019, and the content of which is incorporated herein by reference.
15 Background Art
[0002]
A grain oriented electrical steel sheet is the steel sheet where silicon (Si) of
approximately 0.5 to 7 mass% is included and crystal orientation is aligned with
{ 110 }<001> orientation (Goss orientation) by utilizing a phenomenon called secondary
20 recrystallization. Herein, the { 110}<001> orientation represents that { 110} plane of
crystal is aligned parallel to a rolled surface and <00 1 > axis of crystal is aligned parallel
to a rolling direction.
[0003]
The grain oriented electrical steel sheet is mainly used for an iron core of a
25 transformer and the like as a soft magnetic material. Since the grain oriented electrical
2
steel sheet significantly influences a performance of the transformer, investigation has
been eagerly carried out in order to improve excitation characteristics and iron loss
characteristics of the grain oriented electrical steel sheet.
[0004]
5 A typical method for producing the grain oriented electrical steel sheet is as
follows.
A steel piece with a predetermined composition is heated and hot-rolled to
obtain a hot rolled steel sheet. The hot rolled steel sheet is hot-band-annealed as
necessary, and then is cold-rolled to obtain a cold rolled steel sheet. The cold rolled
10 steel sheet is decarburization-annealed to activate primary recrystallization. A
decarburization annealed steel sheet after the decarburization annealing is final-annealed
to activate the secondary recrystallization.
[0005]
After the decarburization annealing and before the final annealing, aqueous
15 slurry including an annealing separator whose main component is MgO is applied to a
surface of the decarburization annealed steel sheet, and then is dried. The
decarburization annealed steel sheet is coiled, and then is final-annealed. During the
final annealing, MgO included in the annealing separator is reacted to Si02 included in
an internally oxidized layer formed on a surface of the steel sheet by the decarburization
20 annealing, and thereby, a primary layer (referred to as "glass film" or "forsterite film")
which mainly includes forsterite (Mg2Si04) is formed on the surface of the steel sheet.
In addition, after forming the glass film (that is, after the final annealing), the solution
which mainly includes colloidal silica and phosphate for instance is applied to the surface
of the final annealed steel sheet and is baked, and thereby, a tension-insulation coating
25 (referred to as "secondary layer") is formed.
3
[0006]
The above glass film functions as an insulator and also improves adhesion of the
tension-insulation coating formed on the glass film. The tension is imparted to the base
steel sheet by adhering the glass film, the tension-insulation coating, and the base steel
5 sheet. As a result, the iron loss as the grain oriented electrical steel sheet decreases.
[0007]
However, since the glass film is a non-magnetic material, the existence of the
glass film is unfavorable from a magnetic standpoint. Moreover, an interface between
the base steel sheet and the glass film has intruding structure such that the glass film is
10 intricate! y intertwined therewith, and the intruding structure tends to suppress domain
wall motion when the grain oriented electrical steel sheet is magnetized. Thus, the
existence of the glass film may cause an increase in the iron loss.
[0008]
For instance, in a case where the formation of the glass film is suppressed, the
15 formation of the intruding structure may be suppressed, and thus, the domain wall may
easily move during being magnetized. However, in a case where the formation of the
glass film is simply suppressed, the adhesion of the tension-insulation coating is not
ensured, and thus, the sufficient tension is not imparted to the base steel sheet. As a
result, it is difficult to reduce the iron loss.
20 [0009]
As described above, at present, in a case where the glass film is removed from
the grain oriented electrical steel sheet, the domain wall may be easily moved, and thus,
it is expected that the magnetic characteristics are improved. On the other hand, in the
above case, the tension is hardly imparted to the base steel sheet, and thus, it is
25 unavoidable that the magnetic characteristics (especially, the iron loss characteristics)
5
4
deteriorate. Therefore, in a case where the grain oriented electrical steel sheet in which
the glass film is removed whereas the coating adhesion is ensured is realized, it is
expected that the magnetic characteristics are improved.
[0010]
In the past, it has been investigated to improve the adhesion of the
tension-insulation coating for the grain oriented electrical steel sheet without the glass
film.
[0011]
For instance, Patent Document 1 discloses technique to wash a steel sheet by
10 being immersed in aqueous solution of 2 to 30% as sulfuric acid concentration with
sulfuric acid or sulfate before forming a tension-insulation coating. Patent Document 2
discloses technique to conduct pretreatment for a steel sheet surface using oxidizing acid
before forming a tension-insulation coating. Patent Document 3 discloses a grain
oriented silicon steel sheet where an externally oxidized layer containing mainly silica is
15 included and where metallic iron of 30% or less in cross-sectional area fraction is
included in the externally oxidized layer. Patent Document 4 discloses a grain oriented
electrical steel sheet where fine linear grooves are directly formed on a base steel surface
of the grain oriented electrical steel sheet and where the fine linear grooves are with
depth of 0.05 to 2 J.lm and with an interval of 0.05 to 2 J.lm.
20
Related Art Documents
Patent Documents
[0012]
[Patent Document 1] Japanese Unexamined Patent Application, First
25 Publication No. H05-311453
5
10
5
[Patent Document 2] Japanese Unexamined Patent Application, First
Publication No. 2002-249880
[Patent Document 3] Japanese Unexamined Patent Application, First
Publication No. 2003-313644
[Patent Document 4] Japanese Unexamined Patent Application, First
Publication No. 2001-303215
Summary of Invention
Technical Problem to be Solved
[0013]
As described above, the grain oriented electrical steel sheet without the glass
film is inferior in the adhesion of the tension-insulation coating. For instance, in a case
where the above grain oriented electrical steel sheet is held for long time, the
tension-insulation coating may be delaminated. In the case, the tension is not imparted
15 to the base steel sheet. For the grain oriented electrical steel sheet, it is exceedingly
important to improve the adhesion of the tension-insulation coating.
[0014]
The techniques disclosed in Patent Document 1 to Patent Document 4 intend to
improve the adhesion of the tension-insulation coating respectively. However, in the
20 techniques, it is unclear that the adhesion is stably obtained and that the effect in
improving the iron loss is obtained thereby. The above techniques are not enough to
obtain the effect.
[0015]
Moreover, when the magnetic domain refining treatment is conducted for the
25 grain oriented electrical steel sheet without the glass film by laser irradiation and the like
6
in order to improve the iron loss, the effect in improving the iron loss may not be
obtained stably in many cases (the iron loss may fluctuate).
[0016]
The present invention has been made in consideration of the above mentioned
5 situations. An object of the invention is to provide the grain oriented electrical steel
sheet in which the adhesion of the tension-insulation coating is excellent and the effect in
improving the iron loss is obtained stably (the fluctuation of the iron loss is small) even
without the glass film (forsterite film). In addition, an object of the invention is to
provide the method for forming the above insulation coating and for producing the above
10 grain oriented electrical steel sheet.
15
20
25
Solution to Problem
[0017]
An aspect of the present invention employs the following.
[0018]
( 1) A grain oriented electrical steel sheet according to an aspect of the present
invention, the grain oriented electrical steel sheet without a forsterite film includes:
a base steel sheet;
an oxide layer arranged in contact with the base steel sheet; and
a tension-insulation coating arranged in contact with the oxide layer,
wherein the base steel sheet includes, as a chemical composition, by mass%,
2.5 to 4.0% of Si,
0.05 to 1.0% of Mn,
0.02 to 0.50% of Cr,
0 to 0.01% of C,
5
10
0 to 0.005% of S+Se,
0 to 0.01% of sol.Al,
0 to 0.005% of N,
0 to 0.03% of Bi,
0 to 0.03% of Te,
0 to 0.03% of Pb,
0 to 0.50% of Sb,
0 to 0.50% of Sn,
0 to 1.0% of Cu, and
7
a balance consisting of Fe and impurities,
the tension-insulation coating is a phosphate-silica mixed tension-insulation
coating with an average thickness of 1 to 3 ~m,
when a glow discharge spectroscopy is conducted in a region from a surface of
the tension-insulation coating to an inside of the base steel sheet, when a sputtering time
15 at which a Fe emission intensity becomes 0.5 times as compared with a saturation value
20
thereof on a depth profile is referred to as Feo.s in unit of seconds, and when a sputtering
time at which a Fe emission intensity becomes 0.05 times as compared with the
saturation value on the depth profile is referred to as Feo.os in unit of seconds, the Feo.s
and the Feo.os satisfy (Feo.s - Feo.os) I Feo.s 2:: 0.35,
when a sputtering time at which a Fe emission intensity becomes the saturation
value on the depth profile is referred to as Fesat in unit of seconds, and when a sputtering
time at which a Cr emission intensity becomes a maximal value on the depth profile is
referred to as Crmax in unit of seconds, a maximal point of a Cr emission intensity at
which a Cr emission intensity at the Crmax becomes 0.08 to 0.25 times as compared with
25 a Fe emission intensity at the Crmax is included between the Feo.os and the Fesat on the
8
depth profile, and
a magnetic flux density B8 in a rolling direction of the grain oriented electrical
steel sheet is 1. 90 T or more.
(2) A forming method for an insulation coating of a grain oriented electrical
5 steel sheet according to an aspect of the present invention, the forming method for the
insulation coating of the grain oriented electrical steel sheet without a forsterite film
includes an insulation coating forming process of forming a tension-insulation coating on
a steel substrate,
10
15
20
25
wherein, in the insulation coating forming process,
a solution for forming a phosphate-silica mixed tension-insulation coating is
applied to an oxide layer of the steel substrate and the solution is baked so as to form the
tension-insulation coating with an average thickness of 1 to 3 ~m,
the steel substrate includes a base steel sheet and the oxide layer arranged in
contact with the base steel sheet,
the base steel sheet includes, as a chemical composition, by mass%,
2.5 to 4.0% of Si,
0.05 to 1.0% of Mn,
0.02 to 0.50% of Cr,
0 to 0.01% of C,
0 to 0.005% of S+Se,
0 to 0.01% of sol.Al,
0 to 0.005% of N,
0 to 0.03% of Bi,
0 to 0.03% of Te,
0 to 0.03% of Pb,
5
0 to 0.50% of Sb,
0 to 0.50% of Sn,
0 to 1.0% of Cu, and
9
a balance consisting of Fe and impurities,
when a glow discharge spectroscopy is conducted in a region from a surface of
the oxide layer to an inside of the base steel sheet, when a sputtering time at which a Fe
emission intensity becomes a saturation value thereof on a depth profile is referred to as
Fesat in unit of seconds, a plateau region of a Fe emission intensity where a Fe emission
intensity stays for Fesat x 0.1 seconds or more in a range of 0.40 to 0.80 times as
10 compared with the saturation value is included between 0 second and the Fesat on the
depth profile,
when a sputtering time at which a Cr emission intensity becomes a maximal
value on the depth profile is referred to as Crmax in unit of seconds, a maximal point of a
Cr emission intensity at which a Cr emission intensity at the Crmax becomes 0.01 to 0.03
15 times as compared with a Fe emission intensity at the Crmax is included between the
plateau region and the Fesat on the depth profile, and
when a sputtering time at which a Si emission intensity becomes a maximal
value on the depth profile is referred to as Simax in unit of seconds, a maximal point of a
Si emission intensity at which a Si emission intensity at the Simax becomes 0.06 to 0.15
20 times as compared with a Fe emission intensity at the Simax is included between the Crmax
and the Fesat on the depth profile.
25
(3) A producing method for a grain oriented electrical steel sheet according to
an aspect of the present invention, the producing method for the grain oriented electrical
steel sheet without a forsterite film includes
a hot rolling process of heating and thereafter hot-rolling a steel piece to obtain a
10
hot rolled steel sheet,
a hot band annealing process of optionally annealing the hot rolled steel sheet to
obtain a hot band annealed steel sheet,
a cold rolling process of cold-rolling the hot rolled steel sheet or the hot band
5 annealed steel sheet by cold-rolling once or by cold-rolling plural times with an
intermediate annealing to obtain a cold rolled steel sheet,
a decarburization annealing process of decarburization -annealing the cold rolled
steel sheet to obtain a decarburization annealed steel sheet,
a final annealing process of applying an annealing separator to the
10 decarburization annealed steel sheet and thereafter final-annealing the decarburization
annealed steel sheet to obtain a final annealed steel sheet,
15
20
25
an oxidizing process of conducting a washing treatment, a pickling treatment,
and a heat treatment in turn for the final annealed steel sheet to obtain an oxidized steel
sheet, and
an insulation coating forming process of applying a solution for forming a
phosphate-silica mixed tension-insulation coating to a surface of the oxidized steel sheet
and of baking the solution so as to form the tension-insulation coating with an average
thickness of 1 to 3 ~m,
wherein, in the hot rolling process,
the steel piece includes, as a chemical composition, by mass%,
2.5 to 4.0% of Si,
0.05 to 1.0% of Mn,
0.02 to 0.50% of Cr,
0.02 to 0.10% ofC,
0.005 to 0.080% of S+Se,
5
10
0.01 to 0.07% of sol.Al,
0.005 to 0.020% of N,
0 to 0.03% of Bi,
0 to 0.03% of Te,
0 to 0.03% of Pb,
0 to 0.50% of Sb,
0 to 0.50% of Sn,
0 to 1.0% of Cu, and
11
a balance consisting of Fe and impurities, and
wherein, in the oxidizing process,
as the washing treatment, a surface of the final annealed steel sheet is washed,
as the pickling treatment, the final annealed steel sheet is pickled using a sulfuric
acid of 2 to 20 mass% at 70 to 90°C, and
as the heat treatment, the final annealed steel sheet is held in a temperature range
15 of 700 to 900°C for 10 to 60 seconds in a mixed atmosphere of nitrogen and hydrogen
where a dew point is 10 to 30°C and a hydrogen concentration is 0 to 4 volume%.
( 4) In the producing method for the grain oriented electrical steel sheet
according to (3),
in the final annealing process, the annealing separator may include MgO, Ah03,
20 and a bismuth chloride.
25
( 5) In the producing method for the grain oriented electrical steel sheet
according to (3) or ( 4 ),
in the hot rolling process, the steel piece may include, as the chemical
composition, by mass%, at least one selected from a group consisting of
0.0005 to 0.03% of Bi,
5
0.0005 to 0.03% of Te, and
0.0005 to 0.03% of Pb.
Effects of Invention
[0019]
12
According to the above aspects of the present invention, it is possible to provide
the grain oriented electrical steel sheet in which the adhesion of the tension-insulation
coating is excellent and the effect in improving the iron loss is obtained stably (the
fluctuation of the iron loss is small) even without the glass film (forsterite film). In
10 addition, it is possible to provide the method for forming the above insulation coating
and for producing the above grain oriented electrical steel sheet.
[0020]
Specifically, according to the above aspects of the present invention, the glass
film is not included, the formation of the intruding structure is suppressed, and thereby,
15 the domain wall can easily move. In addition, the layering structure is controlled, the
adhesion of the tension-insulation coating is ensured, and thereby, the sufficient tension
can be imparted to the base steel sheet. As a result, it is possible to obtain the excellent
magnetic characteristics as the grain oriented electrical steel sheet. In addition,
according to the above aspects of the present invention, the effect in improving the iron
20 loss is obtained stably (the fluctuation of the iron loss is small).
Brief Description of Drawings
[0021]
Fig. 1A is a cross-sectional illustration showing a grain oriented electrical steel
25 sheet according to an embodiment of the present invention.
5
13
Fig. 1B is a cross-sectional illustration showing a modification of the grain
oriented electrical steel sheet according to the embodiment.
Fig. 2 is an instance of GDS depth profile of the grain oriented electrical steel
sheet according to the embodiment.
Fig. 3 is an instance of GDS depth profile of the grain oriented electrical steel
sheet different from the embodiment.
Fig. 4 is a flow chart illustrating a forming method for an insulation coating of a
grain oriented electrical steel sheet according to an embodiment of the present invention.
Fig. 5 is an instance of GDS depth profile of a steel substrate to be used in the
10 forming method for the insulation coating of the grain oriented electrical steel sheet
15
according to the embodiment.
Fig. 6 is an instance of GDS depth profile of a steel substrate not to be used in
the forming method for the insulation coating of the grain oriented electrical steel sheet
according to the embodiment.
Fig. 7 is a flow chart illustrating a producing method for a grain oriented
electrical steel sheet according to an embodiment of the present invention.
Detailed Description of Preferred Embodiments
[0022]
20 Hereinafter, a preferred embodiment of the present invention is described in
detail. However, the present invention is not limited only to the configuration which is
disclosed in the present embodiment, and various modifications are possible without
departing from the aspect of the present invention. In addition, the limitation range as
described below includes a lower limit and an upper limit thereof. However, the value
25 represented by "more than" or "less than" does not include in the limitation range.
14
Unless otherwise noted,"%" of the chemical composition represents "mass%".
[0023]
Moreover, in the embodiment and the drawings, duplicate explanations in regard
to the component which has the substantial same function are omitted by adding the same
5 reference sign.
[0024]
The present inventors have made a thorough investigation to improve the
adhesion of the tension-insulation coating for the grain oriented electrical steel sheet
without the glass film (forsterite film). As a result, it has been found that, even without
10 the glass film, the coating adhesion can be ensured by forming a favorable oxide layer,
the favorable oxide layer being formed by the following treatments. Specifically, a final
annealed steel sheet without the glass film after final annealing is subjected to washing
treatment of washing a surface thereof, to pickling treatment using sulfuric acid, and then
to heat treatment in predetermined atmosphere.
15 [0025]
Moreover, although there has been a problem such that the iron loss fluctuates
after laser irradiation in the grain oriented electrical steel sheet without the glass film, it
has been found that the fluctuation of the iron loss is improved by controlling the
layering structure. It is presumed that, the layering structure is controlled to be the
20 above, the Fe component is controlled in the tension-insulation coating, the appearance is
changed, and as a result, the effect of the laser irradiation is obtained stably.
[0026]
< Grain Oriented Electrical Steel Sheet >
The main features of the grain oriented electrical steel sheet according to the
25 embodiment are described with reference to Figure 1 A and Figure 1 B. Figure 1 A and
15
Figure 1 B are illustrations schematically showing the structure of grain oriented
electrical steel sheet according to the embodiment.
[0027]
As schematically shown in Figure 1 A, the grain oriented electrical steel sheet 10
5 according to the embodiment includes the base steel sheet 11, the oxide layer 15 arranged
in contact with the base steel sheet 11, and the tension-insulation coating 13 arranged in
contact with the oxide layer 15. In the grain oriented electrical steel sheet 10, the glass
film (forsterite film) does not exist between the base steel sheet 11 and the
tension-insulation coating 13. Moreover, in view of the analysis results of glow
10 discharge spectroscopy (GDS), the oxide layer 15 includes specific oxides. In the grain
oriented electrical steel sheet 10, the tension-insulation coating 13 and the oxide layer 15
are generally formed on both sheet surfaces of the base steel sheet 11 as schematically
shown in Figure 1A, but may be formed on at least one sheet surface of the base steel
sheet 11 as schematically shown in Figure 1 B.
15
20
[0028]
Hereinafter, the grain oriented electrical steel sheet 10 according to the
embodiment is explained focusing on its characteristic features. In the following
description, detailed description of known features and features which can be
accomplished by the skilled person may be omitted.
[0029]
( Base Steel Sheet 11 )
The base steel sheet 11 is obtained by using steel piece with a predetermined
chemical composition and applying predetermined production conditions, and thus, the
chemical composition and the texture are controlled. The chemical composition of the
25 base steel sheet 11 is described in detail below.
16
[0030]
(Tension-Insulation Coating 13)
The tension-insulation coating 13 is arranged above the base steel sheet 11
(specifically, above the oxide layer 15 as explained below in detail). The
5 tension-insulation coating 13 ensures the electrical insulation for the grain oriented
electrical steel sheet 10, and thereby, the eddy current loss is reduced. As a result, the
magnetic characteristics (specifically, the iron loss) is improved. In addition to the
electrical insulation, the tension-insulation coating 13 improves corrosion resistance, heat
resistance, slippage, and the like for the grain oriented electrical steel sheet 10.
10
15
20
25
[0031]
Moreover, the tension-insulation coating 13 applies the tension to the base steel
sheet 11. When the tension is applied to the base steel sheet 11, the magnetic domain
wall motion becomes easier during the magnetization process, and thus, the iron loss
characteristics of the grain oriented electrical steel sheet 10 are improved.
[0032]
Moreover, the continuous wave laser beam or the electron beam may be
irradiated on the surface of the tension-insulation coating 13, in order to refine the
magnetic domain.
[0033]
For instance, the tension-insulation coating 13 is formed by applying the
insulation coating forming solution which mainly includes metal phosphate and colloidal
silica to the surface of the oxide layer 15 arranged in contact with the base steel sheet 11
and by baking the above solution.
[0034]
The average thickness of the tension-insulation coating 13 (the average
17
thickness d1 in Figure 1A and Figure 1B) is not particularly limited, but may be 1 to 3 J.lm,
for instance. When the average thickness of the tension-insulation coating 13 is within
the above range, it is possible to favorably improve various characteristics such as
electrical insulation, corrosion resistance, heat resistance, slippage, tension imparting
5 ability. The average thickness d1 of the tension-insulation coating 13 is preferably 2.0
to 3.0 J.lm, and more preferably 2.5 to 3.0 J.lm.
[0035]
Herein, the above average thickness d1 of the tension-insulation coating 13 may
be measured by electromagnetic coating thickness tester (for instance, LE-370 produced
10 by Kett Electric Laboratory).
[0036]
( Oxide Layer 15 )
The oxide layer 15 is the oxide layer which acts as an intermediate layer
between the base steel sheet 11 and the tension-insulation coating 13 in the grain oriented
15 electrical steel sheet 10 according to the embodiment. The oxide layer 15 includes a Cr
concentrated layer in which Cr in the base steel sheet 11 is segregated as explained
below.
[0037]
In the grain oriented electrical steel sheet 10 according to the embodiment, when
20 (Feo.s - Feo.os) I Feo.s 2:: 0.35 is satisfied and a maximal point at which Cr emission
intensity becomes 0.08 to 0.25 times as compared with Fe emission intensity is included,
it is judged that the above oxide layer 15 is included. Herein, the grain oriented
electrical steel sheet which includes the forsterite film and typical oxide layer does not
satisfy the above conditions.
25 [0038]
18
The oxide layer 15 mainly includes iron oxides such as magnetite (Fe304),
hematite (Fe203), and fayalite (Fe2Si04), and Cr included oxides. In addition to the
above oxides, silicon included oxide (Si02) and the like may be included. The
existence of the oxide layer 15 can be confirmed by conducting the glow discharge
5 spectroscopy (GDS) for the grain oriented electrical steel sheet 10.
[0039]
The above various oxides are formed, for instance, by reacting oxygen with the
surface of the final annealed steel sheet. The oxide layer 15 mainly includes the iron
oxides and the Cr included oxides, and thereby, the adhesion with the base steel sheet 11
10 is improved. In general, it is difficult to improve the adhesion between metals and
ceramics. However, in the grain oriented electrical steel sheet 10 according to the
embodiment, the oxide layer 15 is arranged between the base steel sheet 11 and the
tension-insulation coating 13 which is a kind of ceramic, and thereby, it is possible to
improve the adhesion of the tension-insulation coating 13 and the fluctuation of the iron
15 loss after the laser irradiation even without the glass film.
[0040]
The constituent phase in the oxide layer 15 is not particular! y limited. As
necessary, it is possible to identify the constituent phase by X-ray crystallography, X-ray
photoelectron spectroscopy (XPS), Transmission Electron Microscope (TEM), or the
20 like.
[0041]
< Thickness of Grain Oriented Electrical Steel Sheet 10 >
The average thickness of the grain oriented electrical steel sheet 10 according to
the embodiment (the average thickness tin Figure 1A and Figure 1B) is not particularly
25 limited, but may be 0.17 to 0.35 mm for instance.
19
[0042]
< Chemical Composition of Base Steel Sheet 11 >
The chemical composition of the base steel sheet 11 of the grain oriented
electrical steel sheet 10 according to the embodiment is described in detail. Hereinafter,
5 "%" of the amount of respective elements as described below expresses "mass%" unless
otherwise mentioned.
[0043]
In the grain oriented electrical steel sheet 10 according to the embodiment, the
base steel sheet 11 includes, as the chemical composition, base elements, optional
10 elements as necessary, and a balance consisting of Fe and impurities.
[0044]
In the embodiment, the base steel sheet 11 includes Si, Mn, and Cr as the base
elements (main alloying elements).
[0045]
15 ( 2.5 to 4.0% of Si )
Si (silicon) is an element which increases the electric resistance of steel and
which reduces the eddy current loss. When the Si content is less than 2.5%, the above
effect to reduce the eddy current loss is not sufficiently obtained. On the other hand,
when the Si content is more than 4.0%, the cold workability of steel deteriorates. Thus,
20 in the embodiment, the Si content of the base steel sheet 11 is to be 2.5 to 4.0%. The Si
content is preferably 2.7% or more, and more preferably 2.8% or more. Moreover, the
Si content is preferably 3.9% or less, and more preferably 3.8% or less.
[0046]
( 0.05 to 1.00% of Mn )
25 Mn (manganese) forms MnS and MnSe in the production processes by bonding
20
to Sand/or Se explained later. These precipitates act as the inhibitor (inhibitor of
normal grain growth) and induce the secondary recrystallization in steel during final
annealing. Moreover, Mn is an element which improves the hot workability of steel.
When the Mn content is less than 0.05%, the above is not sufficiently obtained. On the
5 other hand, when the Mn content is more than 1.00%, the secondary recrystallization
does not occur and the magnetic characteristics of steel deteriorate. Thus, in the
embodiment, the Mn content of the base steel sheet 11 is to be 0.05 to 1.00%. The Mn
content is preferably 0.06% or more. Moreover, the Mn content is preferably 0.50% or
less.
10 [0047]
( 0.02 to 0.50% of Cr)
Cr (chrome) is an element which improves the magnetic characteristics.
Moreover, Cr is an element required to obtain the oxide layer 15 including the Cr
concentrated layer. When the base steel sheet 11 includes Cr, the oxide layer 15 is
15 controlled, and as a result, the coating adhesion is improved and the fluctuation of the
iron loss becomes small after the laser irradiation. When the Cr content is less than
0.02%, the above effect is not obtained. Thus, in the embodiment, the Cr content of the
base steel sheet 11 is to be 0.02% or more. The Cr content is preferably 0.03% or more,
and more preferably 0.04% or more. On the other hand, when the Cr content is more
20 than 0.50%, the above effect is not obtained. Thus, in the embodiment, the Cr content
of the base steel sheet 11 is to be 0.50% or less. The Cr content is preferably 0.40% or
less, and more preferably 0.35% or less.
[0048]
In the embodiment, the base steel sheet 11 may include the impurities. The
25 impurities correspond to elements which are contaminated during industrial production
21
of steel from ores and scrap that are used as a raw material of steel, or from environment
of a production process.
[0049]
Moreover, in the embodiment, the base steel sheet 11 may include the optional
5 elements in addition to the base elements and the impurities. For example, as
substitution for a part of Fe which is the balance, the silicon steel sheet may include the
optional elements such as C, S, Se, sol. Al (acid-soluble Al), N, Bi, Te, Pb, Sb, Sn, and
Cu. The optional elements may be included as necessary. Thus, a lower limit of the
respective optional elements does not need to be limited, and the lower limit may be 0%.
10 Moreover, even if the optional elements may be included as impurities, the above
mentioned effects are not affected.
[0050]
( 0 to 0.01% of C )
C (carbon) is an optional element. Cis the element effective for microstructure
15 control until the completion of the decarburization annealing process in the production
processes, and thereby, the magnetic characteristics for the grain oriented electrical steel
sheet are improved. However, as the final product, when the C content of the base steel
sheet 11 is more than 0.01 %, the magnetic characteristics for the grain oriented electrical
steel sheet 10 deteriorate. Thus, in the embodiment, the C content of the base steel
20 sheet 11 is to be 0.01% or less. The C content is preferably 0.005% or less. On the
other hand, the lower limit of the C content of the base steel sheet 11 is not particular! y
limited, but may be 0%. It is preferable that the C content is as low as possible.
However, even when the C content is reduced to less than 0.0001%, the effect for the
microstructure control is saturated, and the producing cost increases. Thus, the C
25 content is preferably 0.0001% or more.
22
[0051]
( 0 to 0.005% in total of S+Se)
S (sulfur) and Se (selenium) are optional elements. Sand Se form MnS and
MnSe which act as the inhibitor by bonding to Mn in the production processes.
5 However, when the total amount of S and Se of the base steel sheet 11 is more than
0.005%, the inhibitor remains in the base steel sheet 11, and the magnetic characteristics
deteriorate. Thus, in the embodiment, the total amount of S and Se of the base steel
sheet 11 is to be 0.005% or less. On the other hand, the lower limit of the total amount
of Sand Se of the base steel sheet 11 is not particularly limited, but may be 0%. It is
10 preferable that the total amount of S and Se is as low as possible. However, even when
the total amount of Sand Se is reduced to less than 0.0001%, the producing cost
increases. Thus, the total amount of S and Se is preferably 0.0001% or more.
15
[0052]
( 0 to 0.01% of sol.Al )
Sol. Al (acid soluble Al) is an optional element. Al forms AlN which acts as
the inhibitor by bonding toN in the production processes. However, when the sol.Al
content is more than 0. 01%, the inhibitor excessively remains in the base steel sheet 11,
and the magnetic characteristics deteriorate. Thus, in the embodiment, the sol.Al
content of the base steel sheet 11 is to be 0.01% or less. The sol.Al content is preferably
20 0.005% or less, and more preferably 0.004% or less. The lower limit of the sol.Al
content of the base steel sheet 11 is not particularly limited, but may be 0%. However,
in order to reduce the sol.Al content to less than 0.0001%, the producing cost increases.
Thus, the sol.Al content is preferably 0.0001% or more.
[0053]
25 ( 0 to 0.005% ofN)
23
N (nitrogen) is an optional element. N forms AlN which acts as the inhibitor
by bonding to Al in the production processes. However, when theN content is more
than 0.005%, the inhibitor excessively remains in the base steel sheet 11, and the
magnetic characteristics deteriorate. Thus, in the embodiment, the N content of the base
5 steel sheet 11 is to be 0.005% or less. TheN content is preferably 0.004% or less. The
lower limit of the N content of the base steel sheet 11 is not particular! y limited, but may
be 0%. However, in order to reduce theN content to less than 0.0001%, the producing
cost increases. Thus, theN content is preferably 0.0001% or more.
[0054]
10 ( 0 to 0.03% ofBi)
( 0 to 0.03% ofTe)
( 0 to 0.03% ofPb)
Bi (bismuth), Te (tellurium), and Pb (lead) are optional elements. When the
amount of each of these elements included in the base steel sheet 11 is 0.03% or less, it is
15 possible to favorably improve the magnetic characteristics for the grain oriented
electrical steel sheet 10. However, when the amount of each of these elements is more
than 0.03% respectively, the steel sheet may become brittle in the higher temperature
range. Thus, in the embodiment, the amount of each of these elements included in the
base steel sheet 11 is to be 0.03% or less. The lower limit of the amount of each of
20 these elements included in the base steel sheet 11 is not particular! y limited, but may be
0%. The lower limit of the amount of each of these elements may be 0.0001%.
[0055]
( 0 to 0.50% of Sb )
( 0 to 0.50% of Sn )
25 ( 0 to 1.0% ofCu)
24
Sb (antimony), Sn (tin), and Cu (copper) are optional elements. When these
elements are included in the base steel sheet 11, it is possible to favorably improve the
magnetic characteristics for the grain oriented electrical steel sheet 10. Thus, in the
embodiment, it is preferable to control the amount of each of these elements included in
5 the base steel sheet 11 to 0.50% or less of Sb, 0.50% or less of Sn, and 1.0% or less of Cu.
10
15
The lower limit of the amount of each of these elements included in the base steel sheet
11 is not particularly limited, but may be 0%. In order to favorably obtain the above
effect, the amount of each of these elements is preferably 0.0005% or more, and more
preferably 0.001% or more.
[0056]
Herein, at least one of Sb, Sn, and Cu may be included in the base steel sheet 11.
Specifically, the base steel sheet 11 may be include at least one of 0.0005 to 0.50% of Sb,
0.0005 to 0.50% of Sn, and 0.0005 to 1.0% of Cu.
[0057]
In the grain oriented electrical steel sheet, the chemical composition changes
relatively drastically (the amount of alloying element decreases) through the
decarburization annealing and through the purification annealing during secondary
recrystallization. Depending on the element, the amount of the element may decreases
through the purification annealing to an undetectable level ( 1 ppm or less) using the
20 typical analysis method. The above mentioned chemical composition is the chemical
25
composition as the final product (the base steel sheet 11 of the grain oriented electrical
steel sheet 1 0). In general, the chemical composition of the final product is different
from the chemical composition of the steel piece (slab) as the starting material.
[0058]
The chemical composition of the base steel sheet 11 of the grain oriented
25
electrical steel sheet 10 may be measured by typical analytical methods for the steel.
For instance, the chemical composition may be measured by using ICP-AES (Inductively
Coupled Plasma-Atomic Emission Spectrometer: inductively coupled plasma emission
spectroscopy spectrometry). Specifically, it is possible to obtain the chemical
5 composition by conducting the measurement by Shimadzu ICPS-81 00 and the like
(measurement device) under the condition based on calibration curve prepared in
advance using samples with 35mm square taken from the base steel sheet 11. In
addition, C and S may be measured by the infrared absorption method after combustion,
and N may be measured by the thermal conductometric method after fusion in a current
1 0 of inert gas.
[0059]
The above chemical composition is the composition of the base steel sheet 11 of
the grain oriented electrical steel sheet 10. When the grain oriented electrical steel sheet
10 used as the measurement sample has the tension-insulation coating 13 and the oxide
15 layer 15 on the surface thereof, the chemical composition is measured after removing the
coating and the like by the typical methods.
[0060]

In the grain oriented electrical steel sheet 10 according to the embodiment, the
20 oxide layer 15 is arranged between the base steel sheet 11 and the tension-insulation
coating 13, and thereby, the oxide layer 15, the tension-insulation coating 13, and the
base steel sheet 11 adhere tightly, even without the glass film (forsterite film).
[0061]
It is possible to judge whether or not the oxide layer 15 is included in the grain
25 oriented electrical steel sheet 10 by the analysis using the glow discharge spectroscopy.
5
26
Specifically, the glow discharge spectroscopy is conduced, and then, the GDS depth
profile may be confirmed. Hereinafter, the GDS depth profile is explained in detail with
reference to Figure 2 and Figure 3.
[0062]
Figure 2 is an instance of the GDS depth profile of the grain oriented electrical
steel sheet 10 according to the embodiment. Figure 2 is the GDS depth profile obtained
by conducting the glow discharge spectroscopy in the region from the surface of the
tension-insulation coating 13 to the inside of the base steel sheet 11. Figure 3 is an
instance of the GDS depth profile of the grain oriented electrical steel sheet which does
10 not include the forsterite film but is different from the grain oriented electrical steel sheet
15
according to the embodiment. Figure 3 is also the GDS depth profile obtained by
conducting the glow discharge spectroscopy in the region from the surface of the
tension-insulation coating to the inside of the base steel sheet.
[0063]
For both grain oriented electrical steel sheets of Figure 2 and Figure 3, the
tension-insulation coating which is based on phosphate-silica mixture which mainly
includes aluminum phosphate and colloidal silica and includes Cr has been formed. In
the GDS depth profiles shown as Figure 2 and Figure 3, the GDS analysis has been
conducted from the surface of the grain oriented electrical steel sheet to approximately 4
20 to 8 ~m in depth.
[0064]
GDS is a method of measuring an amount of target element at each position in
the thickness direction of the measured sample while sputtering the surface of the
measured sample. The horizontal axis of Figure 2 and Figure 3 corresponds to the
25 sputtering time (seconds) (in other words, elapsed time from starting the measurement),
5
27
and the position at which the sputtering time is 0 second corresponds to the surface
position of the grain oriented electrical steel sheet to be measured. The vertical axis of
Figure 2 and Figure 3 corresponds to the emission intensity (a. u.) of each element.
[0065]
First, in Figure 2 and Figure 3, attention is directed to a region from the
sputtering start until the emission intensity derived from Fe (hereinafter, referred to as Fe
emission intensity) starts to remarkably increase (in Figure 2 and Figure 3, the region
where the sputtering time is approximately 0 to 40 seconds). As clearly shown in
Figure 2, in the region, the emission peak derived from Al is noticeably detected.
10 Moreover, it seems that the emission intensities derived from Si and P decrease gradually,
and the emission peaks which are gently and broadly distributed are exist. Moreover,
the emission peak derived from Cr is detected. It seems that Al, Si, and P detected in
the region are originated from the aluminum phosphate and the colloidal silica which are
used for the tension-insulation coating. Thus, the region until the Fe emission intensity
15 starts to remarkably increase (the region where the sputtering time is 0 to 40 seconds in
Figure 2) can be regarded as the tension-insulation coating in the layering structure of the
grain oriented electrical steel sheet. A region where the sputtering time is longer than
that of the above region can be regarded as the oxide layer and the base steel sheet.
20
[0066]
Moreover, the Fe emission intensity shows a profile such that the Fe emission
intensity starts to gradually increase from the surface vicinity of the grain oriented
electrical steel sheet (the position at which the sputtering time is approximately 0 second
in Figure 2), starts to remarkably increase from a certain position (the position at which
the sputtering time is approximately 40 seconds in Figure 2), and thereafter, saturates to a
25 certain value. It seems that Fe detected in the profile is mainly originated from the base
28
steel sheet. Thus, a region where the Fe emission intensity is saturated can be regarded
as the base steel sheet in the layering structure of the grain oriented electrical steel sheet.
[0067]
In the embodiment, a position (sputtering time) at which the Fe emission
5 intensity becomes 0.05 times as compared with the Fe emission intensity of the base steel
sheet (i.e. the saturation value of the Fe emission intensity) on the depth profile is
regarded as a position at which the Fe content starts to increase in the tension-insulation
coating 13 and the oxide layer 15, and the sputtering time is expressed as "Feo.os" in unit
of seconds.
10 [0068]
Moreover, an interface between the oxide layer 15 and the base steel sheet 11 is
rarely horizontal. In the embodiment, a position (sputtering time) at which the Fe
emission intensity becomes 0.5 times as compared with the Fe emission intensity of the
base steel sheet (i.e. the saturation value of the Fe emission intensity) on the depth profile
15 is regarded as the interface between the oxide layer 15 and the base steel sheet 11, and
the sputtering time is expressed as "Feo.s" in unit of seconds.
[0069]
Moreover, the value "(Feo.s - Feo.os)" can be regarded as a region (thickness)
where the Fe content is high in the tension-insulation coating 13 and the oxide layer 15.
20 Thus, the value "(Feo.s - Feo.os) I Feo.s" corresponds to the ratio of the thickness where the
Fe content is high to the total thickness of the tension-insulation coating 13 and the oxide
layer 15.
[0070]
In the grain oriented electrical steel sheet 10 according to the embodiment, the
25 Feo.s and the Feo.os satisfy the following (formula 101).
[0071]
(Feo.s - Feo.os) I Feo.s 2:: 0.35
[0072]
29
---(formula 101)
Moreover, in Figure 2 which is the GDS depth profile of the grain oriented
5 electrical steel sheet 10 according to the embodiment, a maximal point of the Cr emission
intensity is included at a position at which the sputtering time is approximately 55
seconds while the Fe emission intensity increases from the surface and saturates. The
existence of the above maximal point of the Cr emission intensity indicates that the Cr
concentrated layer is included in the vicinity of the interface between the oxide layer 15
10 and the base steel sheet 11.
[0073]
In the embodiment, a position (sputtering time) at which the Fe emission
intensity becomes the Fe emission intensity of the base steel sheet (i.e. the saturation
value of the Fe emission intensity) on the depth profile is expressed as "Fesat" in unit of
15 seconds. Moreover, in the embodiment, a position (sputtering time) at which the Cr
emission intensity becomes a maximal value on the depth profile is expressed as "Crmax"
in unit of seconds.
[0074]
In the grain oriented electrical steel sheet 10 according to the embodiment, the
20 maximal point of the Cr emission intensity is included between the Feo.os and the Fesat on
the depth profile. Specifically, the maximal point of the Cr emission intensity at which
the Cr emission intensity at the Crmax becomes 0.08 to 0.25 times as compared with the
Fe emission intensity at the Crmax is included between the Feo.os and the Fesat on the depth
profile. A region where the maximal point of the Cr emission intensity is included can
25 be regarded as the Cr concentrated layer.
30
[0075]
In the grain oriented electrical steel sheet 10 according to the embodiment, by
satisfying the above (formula 101) and by including the above Cr concentrated layer, the
coating adhesion is improved and the fluctuation of the iron loss becomes small even
5 after the laser irradiation. The reason why the above effect is obtained is not clear at
present. However, in the grain oriented electrical steel sheet 10 according to the
embodiment, the appearance becomes dark brown due to the above structure. Thus, it
seems that the reflectance of laser light for the magnetic domain refining treatment is
reduced, and thereby, the effect in improving the iron loss by the laser irradiation is
10 obtained stably.
[0076]
On the other hand, Figure 3 is the GDS depth profile of the grain oriented
electrical steel sheet which does not include the forsterite film but is different from to the
embodiment. The GDS depth profile of Figure 3 is quite different from the GDS depth
15 profile of Figure 2. Moreover, in the GDS depth profile of Figure 3, the maximal point
of the Cr emission intensity satisfying the above conditions is not included, and also, the
above (formula 101) is not satisfied. In the grain oriented electrical steel sheet in regard
to Figure 3, the appearance becomes light gray.
[0077]
20 Herein, the value "(Feo.s - Feo.os) I Feo.s" is preferably 0.36 or more, and more
25
preferably 0.37 or more. At this time, the coating adhesion is favorably improved.
The upper limit of "(Feo.s- Feo.os) I Feo.s" is not particularly limited, but may be 0.75 for
instance.
[0078]
Moreover, with respect to the maximal point of the Cr emission intensity which
5
31
is included between the Feo.os and the Fesat on the depth profile, the Cr emission intensity
is preferably 0.09 times or more and more preferably 0.10 times or more as compared
with the Fe emission intensity at the Crmax. The value is preferably 0.23 times or less
and more preferably 0.22 times or less.
[0079]
GDS is a method of analyzing an area of approximately 4 mm diameter with
sputtering. Thus, it seems that the GDS depth profile expresses average behavior of
each element in the area which is approximately 4 mm diameter in sample. Moreover,
the grain oriented electrical steel sheet may be coiled into a coil shape, and it is
10 considered that the GDS depth profiles are the substantial same at any points in width
direction in so far as the points are certain distance away from the head of the coil.
Moreover, when the substantial same GDS depth profiles are obtained at both the head
and tail of the coil, it is considered that the substantial same GDS depth profiles are
obtained in the whole coil.
15 [0080]
GDS is conducted in a region from a surface of the tension-insulation coating to
an inside of the base steel sheet. The conditions for GDS analysis may be as follows.
The measurement may be conducted under conditions such that output is 30W, Ar
pressure is 3 hPa, measurement area is 4 mm diameter, and measurement time is 100
20 seconds in high frequency mode using a typical glow discharge spectrum analyzer (for
instance, GDA 750 produced by Rigaku Corporation).
[0081]
Herein, it is preferable to judge the above (formula 101) and the above Cr
concentrated layer after smoothing the measured GDS depth profile. In order to smooth
25 the GDS depth profile, for instance, a simple moving average method may be used.
5
10
32
Moreover, the sputtering time at which the Fe emission intensity becomes the saturation
value may be specified as 100 seconds for instance.
[0082]
< Forsterite Film >
The grain oriented electrical steel sheet 10 according to the embodiment does
not include the forsterite film. In the embodiment, it may be judged by the following
procedure whether or not the grain oriented electrical steel sheet 10 includes the forsterite
film.
[0083]
Whether or not the grain oriented electrical steel sheet 10 includes the forsterite
film may be confirmed by X-ray diffraction method. For instance, the X-ray diffraction
may be conducted for the surface after removing the tension-insulation coating 13 and
the like from the grain oriented electrical steel sheet 10, and the obtained X-ray
diffraction spectrum may be collated with PDF (Powder Diffraction File). The
15 forsterite (Mg2Si04) may be identified by JCPDS No. 34-189. In the embodiment,
20
when the main constituent phase in the above X-ray diffraction spectrum is not the
forsterite, the grain oriented electrical steel sheet 10 is judged not to include the forsterite
film.
[0084]
In order to only remove the tension-insulation coating 13 from the grain oriented
electrical steel sheet 10, the grain oriented electrical steel sheet 10 with the coating may
be immersed in hot alkaline solution. Specifically, it is possible to remove the
tension-insulation coating 13 and the like from the grain oriented electrical steel sheet 10
by immersing the steel sheet in sodium hydroxide aqueous solution which includes 30
25 mass% of NaOH and 70 mass% of H20 at 80°C for 20 minutes, washing it with water,
33
and then by drying it. In general, only insulation coating is removed by the alkaline
solution, and the forsterite film is removed by the acidic solution such as hydrochloric
acid. Thus, in a case where the forsterite film is included, by immersing in the above
alkaline solution, the tension-insulation coating 13 is removed, and the forsterite film is
5 exposed.
[0085]
< Magnetic Characteristics >
The magnetic characteristics of the grain oriented electrical steel sheet may be
measured on the basis of the epstein test regulated by JIS C2550: 2011, the single sheet
10 tester (SST) method regulated by JIS C 2556: 2015, and the like. In the grain oriented
electrical steel sheet 10 according to the embodiment, the magnetic characteristics may
be evaluated by adopting the single sheet tester method regulated by JIS C 2556: 2015
among the above methods.
15
20
[0086]
In the grain oriented electrical steel sheet 10 according to the embodiment, the
average magnetic flux density B8 in the rolling direction (the magnetic flux density
under the magnetizing field of 800A/m) may be 1.90 Tor more. The upper limit of the
magnetic flux density is not particularly limited, but may be 2.02 T for instance.
[0087]
When a steel ingot is formed in vacuum furnace and the like for the research and
development, it is difficult to take a test piece with the same size as that industrially
produced. In the case, for instance, the test piece with a width of 60 mm and a length of
300 mm may be taken, and the measurement may be conducted in accordance with the
single sheet tester method. Moreover, the measured value may be multiplied by the
25 correction factor in order to obtain the measured value equivalent to that based on the
5
34
epstein test. In the embodiment, the measurement is conducted in accordance with the
single sheet tester method.
[0088]
< Forming Method for Insulation Coating of Grain Oriented Electrical Steel Sheet >
Next, a forming method for the insulation coating of the grain oriented electrical
steel sheet according to a preferred embodiment of the present invention is described.
The forming method for the insulation coating of the grain oriented electrical steel sheet
according to the embodiment includes the insulation coating forming process. In the
insulation coating forming process, the solution for forming the tension-insulation
10 coating is applied to a steel substrate, and the solution is baked, in order to form the
tension-insulation coating.
[0089]
Figure 4 is a flow chart illustrating an instance of the forming method for the
insulation coating of the grain oriented electrical steel sheet according to the embodiment.
15 As shown in Figure 4, in the forming method for the insulation coating of the grain
oriented electrical steel sheet according to the embodiment, the steel substrate which
does not include the forsterite film is prepared (step S11), and the tension-insulation
coating is formed on a surface of the steel substrate (stepS 13). The stepS 13
corresponds to the insulation coating forming process.
20
25
[0090]
The above steel substrate includes the base steel sheet and the oxide layer
arranged in contact with the base steel sheet. The steel substrate does not include the
glass film (forsterite film).
[0091]
The base steel sheet of the steel substrate includes, as the chemical composition,
5
10
15
20
25
by mass%,
2.5 to 4.0% of Si,
0.05 to 1.0% of Mn,
0.02 to 0.50% of Cr,
0 to 0.01% of C,
0 to 0.005% of S+Se,
0 to 0.01% of sol.Al,
0 to 0.005% of N,
0 to 0.03% of Bi,
0 to 0.03% of Te,
0 to 0.03% of Pb,
0 to 0.50% of Sb,
0 to 0.50% of Sn,
0 to 1.0% of Cu, and
35
a balance consisting of Fe and impurities.
[0092]
The above chemical composition of the base steel sheet is identical to the
chemical composition of the base steel sheet 11 explained above, and thus, the detail
explanation is omitted.
[0093]
The oxide layer of the steel substrate includes a layer including mainly iron
oxides, a Si -Cr included oxide layer, and a Si included oxide layer. The oxide layer is
not the forsterite film. The details are explained below.
[0094]
The steel substrate which is utilized for the forming method for the insulation
5
36
coating of the grain oriented electrical steel sheet according to the embodiment satisfies
the following conditions (I) to (III). Herein, the steel substrate which includes the
forsterite film and typical steel substrate do not satisfy the conditions.
[0095]
(I) When a glow discharge spectroscopy is conducted in a region from a surface
of the oxide layer to an inside of the base steel sheet, when a sputtering time at which a
Fe emission intensity becomes a saturation value thereof on a depth profile is referred to
as Fesat in unit of seconds, a plateau region of a Fe emission intensity where a Fe
emission intensity stays for Fesat x 0.1 seconds or more in a range of 0.40 to 0.80 times as
10 compared with the saturation value is included between 0 second and the Fesat on the
depth profile.
(II) When a sputtering time at which a Cr emission intensity becomes a maximal
value on the depth profile is referred to as Crmax in unit of seconds, a maximal point of a
Cr emission intensity at which a Cr emission intensity at the Crmax becomes 0.01 to 0.03
15 times as compared with a Fe emission intensity at the Crmax is included between the
plateau region and the Fesat on the depth profile.
(III) When a sputtering time at which a Si emission intensity becomes a maximal
value on the depth profile is referred to as Simax in unit of seconds, a maximal point of a
Si emission intensity at which a Si emission intensity at the Simax becomes 0.06 to 0.15
20 times as compared with a Fe emission intensity at the Simax is included between the Crmax
and the Fesat on the depth profile.
[0096]
Figure 5 is an instance of GDS depth profile of a steel substrate to be used in the
forming method for the insulation coating of the grain oriented electrical steel sheet
25 according to the embodiment. Figure 5 is the GDS depth profile obtained by
37
conducting the glow discharge spectroscopy in the region from the surface of the oxide
layer to the inside of the base steel sheet. The measurement conditions of the GDS
depth profile of Figure 5 are the same as the measurement conditions of the GDS depth
profile of Figure 2. In Figure 5, the horizontal axis corresponds to the sputtering time
5 (seconds), and the vertical axis corresponds to the emission intensity (a.u.) of each
element.
[0097]
In Figure 5, the Fe emission intensity shows a profile such that the Fe emission
intensity starts to remarkably increase with starting the sputtering, becomes substantially
10 horizontal (plateau) shown as a region surrounded by a broken line in the figure, starts to
increase again, and thereafter, saturates to a certain value. A region where the Fe
emission intensity is saturated can be regarded as the base steel sheet in the layering
structure of the steel substrate. Moreover, the region (plateau region) surrounded by the
broken line in Figure 5 can be regarded as a region including mainly iron oxides in the
15 oxide layer of the steel substrate, because the 0 (oxygen) emission intensity is detected
in the sputtering time which is identical to that of the above region.
[0098]
In a region where the sputtering time is longer than that of the above plateau
region, the Cr emission intensity and the Si emission intensity starts to increase. The Cr
20 emission intensity shows a maximal point (at near 10 seconds of the sputtering time), and
thereafter, gradually approaches a certain value. On the other hand, the Si emission
intensity continues to increase even after the Cr emission intensity starts to gradually
decrease, shows a maximal point (at near 15 seconds of the sputtering time), and
thereafter, gradually approaches a certain value. The asymptotic values of Cr and Si can
25 be regarded as the values corresponding to the Cr content and the Si content of the base
38
steel sheet.
[0099]
A region where the Cr emission intensity shows the maximal point can be
regarded as the Si -Cr included oxide layer in the oxide layer of the steel substrate,
5 because Cr, Si, and 0 are detected. Moreover, a region from the Cr emission intensity
decreasing till the Si emission intensity reaching to the asymptotic value which is a
certain value can be regarded as the Si included oxide layer in the oxide layer of the steel
substrate, because Si and 0 are detected.
10
[0100]
It is confirmed from the GDS depth profile of Figure 5 that the steel substrate to
be used in the forming method for the insulation coating according to the embodiment
includes, from the surface thereof, the layer including mainly iron oxides, the Si-Cr
included oxide layer, the Si included oxide layer, and the base steel sheet. In the
embodiment, the layer including mainly iron oxides, the Si-Cr included oxide layer, and
15 the Si included oxide layer are collectively regarded as the oxide layer.
[0101]
In the embodiment, the steel substrate which includes the above chemical
composition and satisfies the above conditions (I) to (III) is subjected to the insulation
coating forming process. As a result, the grain oriented electrical steel sheet 10 which
20 shows the GDS depth profile such as Figure 2 is produced.
[0102]
Moreover, with respect to the maximal point of the Cr emission intensity which
is included between the plateau region and the Fesat on the depth profile, the Cr emission
intensity is preferably 0.011 times or more and more preferably 0.012 times or more as
25 compared with the Fe emission intensity at the Crmax. The value is preferably 0.029
39
times or less and more preferably 0.028 times or less.
[0103]
Moreover, with respect to the maximal point of the Si emission intensity which
is included between the Crmax and the Fesat on the depth profile, the Si emission intensity
5 is preferably 0.07 times or more and more preferably 0.08 times or more as compared
with the Fe emission intensity at the Simax. The value is preferably 0.14 times or less
and more preferably 0.13 times or less.
[0104]
On the other hand, Figure 6 is the GDS depth profile of the steel substrate which
10 does not include the forsterite film but is different from to the steel substrate to be used
for the embodiment. The GDS depth profile of Figure 6 is quite different from the GDS
depth profile of Figure 5. Moreover, in the GDS depth profile of Figure 6, the maximal
point of the Cr emission intensity and the maximal point of the Si emission intensity are
not included, and the above conditions (I) to (III) are not satisfied.
15 [0105]
Herein, the conditions for GDS analysis, the method for analyzing data, and the
method for judging the presence of the forsterite film are as described above.
[0106]
The solution for forming the phosphate-silica mixed tension-insulation coating
20 is applied to the oxide layer of the steel substrate which includes the above chemical
composition and satisfies the above conditions (I) to (III) and the solution is baked so as
to form the tension-insulation coating with an average thickness of 1 to 3 ~m. The
solution may be applied to both sheet surfaces or one sheet surface of the steel substrate.
[0107]
25 The conditions in the insulation coating forming process are not particularly
40
limited. Known solution for forming the phosphate-silica mixed tension-insulation
coating may be used, and the solution may applied and baked by known method. For
instance, the solution is applied, and thereafter, is held at 850 to 950°C for 10 to 60
seconds. The tension-insulation coating is formed on the steel substrate, and thereby, it
5 is possible to further improve the magnetic characteristics of the grain oriented electrical
steel sheet.
[0108]
Herein, before applying the solution, the surface of the steel substrate to form
the insulation coating may be subjected to optional pretreatment such as degreasing
10 treatment with alkaline, pickling treatment with hydrochloric acid, sulfuric acid,
phosphoric acid, and the like. The pretreatment may not be conducted.
[0109]
The tension-insulation coating is not particular! y limited, and known coating
may be adopted. For instance, the tension-insulation coating may mainly include
15 inorganics and may further include organics. The tension-insulation coating may
mainly include metal phosphate and colloidal silica, and fine particles of organic resin
may be dispersed in the tension-insulation coating.
[0110]
Moreover, following the insulation coating forming process, the flattening
20 annealing may be conducted for straightening. By conducting the flattening annealing
for the grain oriented electrical steel sheet after the insulation coating forming process, it
is possible to favorably reduce the iron loss characteristics.
[0111]
Moreover, the magnetic domain refining treatment may be conducted for the
25 produced grain oriented electrical steel sheet. Herein, the magnetic domain refining
5
41
treatment is the treatment such that the laser beam which refines the magnetic domain is
irradiated to the surface of the grain oriented electrical steel sheet or the groove is formed
on the surface of the grain oriented electrical steel sheet. By conducting the magnetic
domain refining treatment, it is possible to favorably reduce the magnetic characteristics.
[0112]
< Producing Method for Grain Oriented Electrical Steel Sheet >
Next, a producing method for the grain oriented electrical steel sheet according
to a preferred embodiment of the present invention is described in detail with reference to
Figure 7. Figure 7 is a flow chart illustrating an instance of the producing method for
10 the grain oriented electrical steel sheet according to the embodiment.
15
20
[0113]
Herein, the producing method for the grain oriented electrical steel sheet 10 is
not limited to the following method. The following method is just an instance for
producing the grain oriented electrical steel sheet 10.
[0114]
< Overall Flow of Producing Method for Grain Oriented Electrical Steel Sheet >
The producing method for the grain oriented electrical steel sheet according to
the embodiment is for producing the grain oriented electrical steel sheet without the
forsterite film, and the overall flow thereof is as follows.
[0115]
The producing method for the grain oriented electrical steel sheet according to
the embodiment includes the following processes, which are shown in Figure 7.
(S 111) Hot rolling process of heating and thereafter hot-rolling a steel piece
(slab) including predetermined chemical composition to obtain a hot rolled steel sheet.
25 (S 113) Hot band annealing process of optionally annealing the hot rolled steel
5
10
42
sheet to obtain a hot band annealed steel sheet.
(S 115) Cold rolling process of cold-rolling the hot rolled steel sheet or the hot
band annealed steel sheet by cold-rolling once or by cold-rolling plural times with an
intermediate annealing to obtain a cold rolled steel sheet.
(S 117) Decarburization annealing process of decarburization-annealing the cold
rolled steel sheet to obtain a decarburization annealed steel sheet.
(S119) Final annealing process of applying an annealing separator to the
decarburization annealed steel sheet and thereafter final-annealing the decarburization
annealed steel sheet to obtain a final annealed steel sheet.
(S 121) Oxidizing process of conducting a washing treatment, a pickling
treatment, and a heat treatment in turn for the final annealed steel sheet to obtain an
oxidized steel sheet.
(S123) Insulation coating forming process of applying a solution for forming a
tension-insulation coating to a surface of the oxidized steel sheet and of baking the
15 solution.
20
[0116]
The above processes are respectively described in detail. In the following
description, when the conditions of each process are not described, known conditions
may be appropriate! y applied.
[0117]
< Hot Rolling Process >
The hot rolling process (step S 111) is the process of heating and thereafter
hot-rolling the steel piece (for instance, steel ingot such as slab) including predetermined
chemical composition to obtain the hot rolled steel sheet. In the hot rolling process, the
25 steel piece is heat-treated. The heating temperature of the steel piece is preferably in the
5
43
range of 1200 to 1400°C. The heating temperature of the steel piece is preferably
1250°C or more, and preferably 1380°C or more. Subsequently, the heated steel piece
is hot-rolled to obtain the hot rolled steel sheet. The average thickness of the hot rolled
steel sheet is preferably in the range of 2.0 to 3.0 mm for instance.
[0118]
In the producing method for the grain oriented electrical steel sheet according to
the embodiment, the steel piece includes, as the chemical composition, base elements,
optional elements as necessary, and a balance consisting of Fe and impurities.
Hereinafter,"%" of the amount of respective elements as described below expresses
10 "mass%" unless otherwise mentioned.
15
[0119]
In the producing method for the grain oriented electrical steel sheet according to
the embodiment, the steel piece (slab) includes Si, Mn, Cr, C, S+Se, sol. Al, and N as the
base elements (main alloying elements).
[0120]
( 2.5 to 4.0% of Si )
Si is the element which increases the electric resistance of steel and which
reduces the eddy current loss. When the Si content of the steel piece is less than 2.5%,
the above effect to reduce the eddy current loss is not sufficiently obtained. On the
20 other hand, when the Si content of the steel piece is more than 4.0%, the cold workability
of steel deteriorates. Thus, in the embodiment, the Si content of the steel piece is to be
2.5 to 4.0%. The Si content of the steel piece is preferably 2.7% or more, and more
preferably 2.8% or more. Moreover, the Si content of the steel piece is preferably 3.9%
or less, and more preferably 3.8% or less.
25 [0121]
44
( 0.05 to 1.00% of Mn )
Mn forms MnS and MnSe in the production processes by bonding to S and/or Se
explained later. These precipitates act as the inhibitor and induce the secondary
recrystallization in steel during final annealing. Moreover, Mn is an element which
5 improves the hot workability of steel. When the Mn content of the steel piece is less
than 0.05%, the above is not sufficiently obtained. On the other hand, when the Mn
content of the steel piece is more than 1.00%, the secondary recrystallization does not
occur and the magnetic characteristics of steel deteriorate. Thus, in the embodiment,
the Mn content of the steel piece is to be 0.05 to 1.00%. The Mn content of the steel
10 piece is preferably 0.06% or more. Moreover, the Mn content of the steel piece is
preferably 0.50% or less.
[0122]
( 0.02 to 0.50% of Cr)
Cr (chrome) is an element which improves the magnetic characteristics.
15 Moreover, Cr is an element required to obtain the oxide layer 15 including the Cr
concentrated layer. When the base steel sheet 11 includes Cr, the oxide layer 15 is
controlled, and as a result, the coating adhesion is improved and the fluctuation of the
iron loss becomes small after the laser irradiation. When the Cr content is less than
0.02%, the above effect is not obtained. Thus, in the embodiment, the Cr content of the
20 steel piece is to be 0.02% or more. The Cr content is preferably 0.03% or more, and
more preferably 0.04% or more. On the other hand, when the Cr content is more than
0.50%, the above effect is not obtained. Thus, in the embodiment, the Cr content of the
steel piece is to be 0.50% or less. The Cr content is preferably 0.40% or less, and more
preferably 0.35% or less.
25 [0123]
45
( 0.02 to 0.10% of C)
Cis the element effective for microstructure control until the completion of the
decarburization annealing process in the production processes, and thereby, the magnetic
characteristics for the grain oriented electrical steel sheet are improved. When the C
5 content of the steel piece is less than 0.02%, or when the C content of the steel piece is
more than 0.10%, the above effect in improving the magnetic characteristics are not
sufficiently obtained. The C content of the steel piece is preferably 0.03% or more.
Moreover, the C content of the steel piece is preferably 0.09% or less.
[0124]
10 ( 0.005 to 0.080% in total of S+Se )
S and Se form MnS and MnSe which act as the inhibitor by bonding to Mn in
the production processes. When the total amount of Sand Se of the steel piece is less
than 0.005%, it is difficult to obtain the effect for forming MnS and MnSe. On the other
hand, when the total amount of S and Se is more than 0.080%, the magnetic
15 characteristics deteriorate, and the steel sheet may become brittle in the higher
temperature range. Thus, in the embodiment, the total amount of S and Se of the steel
piece is to be 0.005 to 0.080%. The total amount of Sand Se of the steel piece is
preferably 0.006% or more. Moreover, the total amount of S and Se of the steel piece is
preferably 0.070% or less.
20 [0125]
( 0.01 to 0.07% of sol.Al)
Sol. Al forms AlN which acts as the inhibitor by bonding to N in the production
processes. When the sol.Al content of the steel piece is less than 0.01 %, AlN does not
form sufficiently, and thus, the magnetic characteristics deteriorate. On the other hand,
25 when the sol.Al content of the steel piece is more than 0.07%, the magnetic
5
46
characteristics deteriorate, and the cracks tend to occur during cold rolling. Thus, in the
embodiment, the sol.Al content of the steel piece is to be 0.01 to 0.07%. The sol.Al
content of the steel piece is preferably 0.02% or more. Moreover, the sol.Al content of
the steel piece is preferably 0.05% or less.
[0126]
( 0.005 to 0.020% of N)
N forms AlN which acts as the inhibitor by bonding to Al in the production
processes. When theN content of the steel piece is less than 0.005%, AlN does not
form sufficiently, and thus, the magnetic characteristics deteriorate. On the other hand,
10 when the N content of the steel piece is more than 0.020%, AlN becomes difficult to act
15
as the inhibitor, and thus, the secondary recrystallization becomes difficult to occur. In
addition, the cracks tend to occur during cold rolling. Thus, in the embodiment, the N
content of the steel piece is to be 0.005 to 0.020%. TheN content of the steel piece is
preferably 0.012% or less, and more preferably 0.010% or less.
[0127]
In the producing method for the grain oriented electrical steel sheet according to
the embodiment, the steel piece (slab) may include the impurities. The impurities
correspond to elements which are contaminated during industrial production of steel
from ores and scrap that are used as a raw material of steel, or from environment of a
20 production process.
[0128]
Moreover, in the embodiment, the steel piece may include the optional elements
in addition to the base elements and the impurities. For example, as substitution for a
part of Fe which is the balance, the silicon steel sheet may include the optional elements
25 such as Bi, Te, Pb, Sb, Sn, and Cu. The optional elements may be included as necessary.
47
Thus, a lower limit of the respective optional elements does not need to be limited, and
the lower limit may be 0%. Moreover, even if the optional elements may be included as
impurities, the above mentioned effects are not affected.
[0129]
5 ( 0 to 0.03% ofBi)
( 0 to 0.03% ofTe)
( 0 to 0.03% ofPb)
Bi, Te, and Pb are optional elements. When the amount of each of these
elements included in the steel piece is 0.03% or less, it is possible to favorably improve
10 the magnetic characteristics for the grain oriented electrical steel sheet. However, when
the amount of each of these elements is more than 0.03% respectively, the steel sheet
may become brittle in the higher temperature range. Thus, in the embodiment, the
amount of each of these elements included in the steel piece is to be 0.03% or less. The
lower limit of the amount of each of these elements included in the steel piece is not
15 particularly limited, but may be 0%. In order to favorably obtain the above effect, the
amount of each of these elements is preferably 0.0005% or more, and more preferably
0.001% or more.
[0130]
Herein, at least one of Bi, Te, and Pb may be included in the steel piece.
20 Specifically, the steel piece may be include at least one of 0.0005 to 0.03% of Bi, 0.0005
to 0.03% of Te, and 0.0005 to 0.03% of Pb.
[0131]
( 0 to 0.50% of Sb )
( 0 to 0.50% of Sn )
25 ( 0 to 1.0% ofCu)
48
Sb, Sn, and Cu are optional elements. When these elements are included in the
steel piece, it is possible to favorably improve the magnetic characteristics for the grain
oriented electrical steel sheet. Thus, in the embodiment, it is preferable to control the
amount of each of these elements included in the steel piece to 0.50% or less of Sb,
5 0.50% or less of Sn, and 1.0% or less of Cu. The lower limit of the amount of each of
these elements included in the steel piece is not particular! y limited, but may be 0%. In
order to favorably obtain the above effect, the amount of each of these elements is
preferably 0.0005% or more, and more preferably 0.001% or more.
10
[0132]
Herein, at least one of Sb, Sn, and Cu may be included in the steel piece.
Specifically, the steel piece may be include at least one of 0.0005 to 0.50% of Sb, 0.0005
to 0.50% of Sn, and 0.0005 to 1.0% of Cu.
[0133]
The chemical composition of the steel piece may be measured by typical
15 analytical methods for the steel. For instance, the chemical composition may be
measured on the basis of the above analytical method.
[0134]
< Hot Band Annealing Process >
The hot band annealing process (step S 113) is the process of optionally
20 annealing the hot rolled steel sheet after the hot rolling process to obtain the hot band
annealed steel sheet. By conducting the annealing for the hot rolled steel sheet, the
recrystallization occurs in steel, and finally, the excellent magnetic characteristics can be
obtained.
[0135]
25 The heating method is not particular! y limited, and known heating method may
5
49
be adopted. Moreover, the annealing conditions are not particular! y limited. For
instance, the hot rolled steel sheet may be held in the temperature range of 900 to 1200°C
for 10 seconds to 5 minutes.
[0136]
The hot band annealing process may be omitted as necessary.
Moreover, after the hot band annealing process and before the cold rolling
process explained below, the surface of the hot rolled steel sheet may be pickled.
[0137]
< Cold Rolling Process >
10 The cold rolling process (step S 115) is the process of cold-rolling the hot rolled
steel sheet after the hot rolling process or the hot band annealed steel sheet after the hot
band annealing process by cold-rolling once or by cold-rolling plural times with the
intermediate annealing to obtain the cold rolled steel sheet. Since the sheet shape of the
hot band annealed steel sheet is excellent due to the hot band annealing, it is possible to
15 reduce the possibility such that the steel sheet is fractured in the first cold rolling. The
cold rolling may be conducted three or more times, but the producing cost increases.
Thus, it is preferable to conduct the cold rolling once or twice.
[0138]
In the cold rolling process, the cold rolling method for the steel sheet is not
20 particularly limited, and known method may be adopted. For instance, the cold rolling
reduction in final cold rolling (cumulative cold rolling reduction without intermediate
annealing or cumulative cold rolling reduction after intermediate annealing) may be in
the range of 80 to 95%.
[0139]
25 Herein, the final cold rolling reduction(%) is defined as follows.
50
Final cold rolling reduction(%)= ( 1 -Sheet thickness of steel sheet after final
cold rolling I Sheet thickness of steel sheet before final cold rolling ) x 100
[0140]
When the final cold rolling reduction is less than 80%, the Goss nuclei may not
5 be formed favorably. On the other hand, when the final cold rolling reduction is more
than 95%, the secondary recrystallization may be unstable in the final annealing process.
Thus, it is preferable that the cold rolling reduction in final cold rolling is 80 to 95%.
[0141]
When conducting the cold rolling plural times with the intermediate annealing,
10 the reduction in first cold rolling may be 5 to 50%, and the holding in the intermediate
annealing may be conducted in the temperature range of 950 to 1200°C for 30 seconds to
30 minutes.
[0142]
The average thickness of the cold rolled steel sheet (thickness after cold rolling)
15 is different from the thickness of the grain oriented electrical steel sheet which includes
the thickness of the tension-insulation coating. For instance, the average thickness of
the cold rolled steel sheet may be 0.10 to 0.50 mm. In the embodiment, even when the
cold rolled steel sheet is the thin sheet whose average thickness is less than 0.22 mm, the
adhesion of the tension-insulation coating is favorably improved. Thus, the average
20 thickness of the cold rolled steel sheet may be 0.17 mm or more and 0.20 mm or less.
[0143]
In the cold rolling process, the aging treatment may be conducted in order to
favorably improve the magnetic characteristics of the grain oriented electrical steel sheet.
For instance, since the thickness of the steel sheet is reduced by plural passes in the cold
25 rolling, the steel sheet may be held in the temperature range of 1 00°C or more for 1
51
minute or more at least once in the interval of plural passes. By the aging treatment, it
is possible to favorably control the primary recrystallized texture in the decarburization
annealing process, and as a result, it is possible to obtain the secondary recrystallized
texture where the { 110}<001> orientation is favorably developed in the final annealing
5 process.
[0144]
< Decarburization Annealing Process >
The decarburization annealing process (step S 117) is the process of
decarburization-annealing the cold rolled steel sheet after the cold rolling process to
10 obtain the decarburization annealed steel sheet. In the decarburization annealing
process, the cold rolled steel sheet is annealed under predetermined conditions in order to
control the primary recrystallized structure.
[0145]
In the producing method for the grain oriented electrical steel sheet according to
15 the embodiment, the annealing conditions in the decarburization annealing process are
not particularly limited, and known conditions may be adopted. For instance, the steel
sheet may be held in the temperature range of 750 to 950°C for 1 to 5 minutes.
Moreover, furnace atmosphere may be known moist atmosphere including hydrogen and
nitrogen.
20 [0146]
< Final Annealing Process >
The final annealing process (step S 119) is the process of applying the annealing
separator to the decarburization annealed steel sheet after the decarburization annealing
process and thereafter final-annealing the decarburization annealed steel sheet to obtain
25 the final annealed steel sheet. In the final annealing, the coiled steel sheet may be held
5
52
at a higher temperature for a long time in general. Thus, in order to suppress the seizure
between the inside and outside of the coiled steel sheet, the annealing separator is applied
to the decarburization annealed steel sheet and is dried before the final annealing.
[0147]
In the final annealing process, the annealing separator applied to the
decarburization annealed steel sheet is not particular! y limited, and known annealing
separator may be adopted. The producing method for the grain oriented electrical steel
sheet according to the embodiment is the method for producing the grain oriented
electrical steel sheet without the glass film (forsterite film), and thus, the annealing
10 separator which does not form the forsterite film may be adopted. In a case where the
15
annealing separator which forms the forsterite film is adopted, the forsterite film may be
removed by grinding or pickling after the final annealing.
[0148]
(Annealing Separator which does not form Forsterite Film)
As the annealing separator which does not form the glass film (forsterite film),
the annealing separator which mainly includes MgO and Ah03 and which includes
bismuth chloride may be utilized. For instance, it is preferable that the annealing
separator includes MgO and Ah03 of 85 mass% or more in total as percent solid, MgO :
Ah03 which is the mass ratio of MgO and Ah03 satisfies 3 : 7 to 7 : 3, and the annealing
20 separator includes the bismuth chloride of 0.5 to 15 mass% as compared with the total
25
amount of MgO and Ah03 as percent solid. The range of the above mass ratio of MgO
and Ah03 and the amount of the above bismuth chloride are determined from the
viewpoint of obtaining the base steel sheet excellent in the surface smoothness without
the glass film.
[0149]
53
In regard to the above mass ratio of MgO and Ah03, when the amount of MgO
exceeds the above range, the glass film may be formed and remained on the steel sheet
surface, and thus, the surface of the base steel sheet may not be smoothed. Moreover, in
regard to the above mass ratio of MgO and Ah03, when the amount of Ah03 exceeds the
5 above range, the seizure of Ah03 may occur, and thus, the surface of the base steel sheet
may not be smoothed. It is more preferable that MgO : Ah03 which is the mass ratio of
MgO and Ah03 satisfies 3.5 : 6.5 to 6.5 : 3.5.
[0150]
In a case where the bismuth chloride is included in the annealing separator, the
10 glass film is easily removed from the steel sheet surface even when the glass film is
formed in the final annealing. When the amount of the bismuth chloride is less than 0.5
mass% as compared with the total amount of MgO and Ah03, the glass film may be
remained. On the other hand, when the amount of the bismuth chloride is more than 15
mass% as compared with the total amount of MgO and Ah03, the effect to suppress the
15 seizure between the steel sheets may not be obtained as the annealing separator. The
amount of the bismuth chloride is more preferably 3 mass% or more, and more
preferably 7 mass% or less, as compared with the total amount ofMgO and Ah03.
[0151]
The type of the bismuth chloride is not particularly limited, and known bismuth
20 chloride may be adopted. For instance, bismuth oxychloride (BiOCl), bismuth
trichloride (BiCb), and the like may be used. Moreover, compounds which can form
the bismuth oxychloride by reaction in the annealing separator during the final annealing
process may be used. For instance, as the compounds which can form the bismuth
oxychloride during the final annealing, a mixture of bismuth compound and metal
25 chloride may be used. For instance, as the bismuth compound, bismuth oxide, bismuth
5
54
hydroxide, bismuth sulfide, bismuth sulfate, bismuth phosphate, bismuth carbonate,
bismuth nitrate, organobismuth compound, bismuth halide, and the like may be used.
For instance, as the metal chloride, iron chloride, cobalt chloride, nickel chloride, and the
like may be used.
[0152]
After applying the above annealing separator which does not form the forsterite
film to the surface of the decarburization annealed steel sheet and drying the annealing
separator, the final annealing is conducted. The annealing conditions in the final
annealing process are not particular! y limited, and known conditions may be adopted.
10 For instance, the steel sheet may be held in the temperature range of 1100 to 1300°C for
10 to 30 hours. Moreover, furnace atmosphere may be known nitrogen atmosphere or
mixed atmosphere of nitrogen and hydrogen. After the final annealing, it is preferable
that the redundant annealing separator is removed from the steel sheet surface by
water-washing or pickling.
15 [0153]
(Annealing Separator which forms Forsterite Film)
As the annealing separator which forms the glass film (forsterite film), the
annealing separator which mainly includes MgO may be utilized. For instance, it is
preferable that the annealing separator includes MgO of 60 mass% or more as percent
20 solid.
[0154]
After applying the annealing separator to the surface of the decarburization
annealed steel sheet and drying the annealing separator, the final annealing is conducted.
The annealing conditions in the final annealing process are not particular! y limited, and
25 known conditions may be adopted. For instance, the steel sheet may be held in the
55
temperature range of 1100 to 1300°C for 10 to 30 hours. Moreover, furnace atmosphere
may be known nitrogen atmosphere or mixed atmosphere of nitrogen and hydrogen.
[0155]
In a case where the annealing separator which forms the forsterite film is used,
5 MgO in the annealing separator reacts with Si02 of the steel sheet surface during the
final annealing, whereby the forsterite (Mg2Si04) is formed. Thus, it is preferable that
the forsterite film formed on the surface is removed by grinding or pickling the surface of
the final annealed steel sheet after the final annealing. The method for removing the
forsterite film from the surface of the final annealed steel sheet is not particularly limited,
10 and known grinding or known pickling may be adopted.
[0156]
For instance, in order to remove the forsterite film by pickling, the final
annealed steel sheet may be immersed in hydrochloric acid of 20 to 40 mass% at 50 to
90°C for 1 to 5 minutes, be water-washed, and then be dried. Moreover, the final
15 annealed steel sheet may be pickled in mixed solution of fluorinated ammonium and
sulfuric acid, be chemically polished in mixed solution of hydrofluoric acid and
hydrogen peroxide solution, be water-washed, and then be dried.
20
[0157]
< Oxidizing Process >
The oxidizing process (step S 121) is the process of conducting the washing
treatment, the pickling treatment, and the heat treatment in turn for the final annealed
steel sheet after the final annealing process (final annealed steel sheet without the
forsterite film) to obtain the oxidized steel sheet. Specifically, the surface of the final
annealed steel sheet is washed as the washing treatment, the final annealed steel sheet is
25 pickled using sulfuric acid of 2 to 20 mass% at 70 to 90°C as the pickling treatment, and
56
the final annealed steel sheet is held in the temperature range of 700 to 900°C for 10 to
60 seconds in the mixed atmosphere of nitrogen and hydrogen where the dew point is 10
to 30°C and the hydrogen concentration is 0 to 4 volume% as the heat treatment.
[0158]
5 ( Washing Treatment )
10
15
The surface of the final annealed steel sheet after the final annealing process is
washed. The method for washing the surface of the final annealed steel sheet is not
particularly limited, and known washing method may be adopted. For instance, the
surface of the final annealed steel sheet may be water-washed.
[0159]
( Pickling Treatment )
The final annealed steel sheet after the washing treatment is pickled using the
sulfuric acid whose concentration is 2 to 20 mass% and whose temperature is 70 to 90°C.
[0160]
When the sulfuric acid is less than 2 mass%, it is difficult to obtain the grain
oriented electrical steel sheet in which (Feo.s - Feo.os) I Feo.s 2:: 0.35 is satisfied and the
maximal point at which the Cr emission intensity becomes 0.08 to 0.25 times as
compared with the Fe emission intensity is included. Also, when the sulfuric acid is
more than 20 mass%, it is difficult to obtain the grain oriented electrical steel sheet
20 having the above features. The concentration of the sulfuric acid is preferably 17
mass% or less, and more preferably 12 mass% or less.
[0161]
Moreover, when the temperature of the sulfuric acid is less than 70°C, the
sufficient adhesion is not obtained. On the other hand, when the temperature of the
57
sulfuric acid is more than 90°C, the effect in improving the adhesion is saturated, and the
tension which is applied to the steel sheet by the insulating coating is reduced. The
temperature of the sulfuric acid is preferably 75°C or more, and more preferably 80°C or
more. The temperature of the sulfuric acid is preferably 88°C or less, and more
5 preferably 85°C or less.
10
[0162]
The time for the pickling treatment is not particularly limited. For instance, the
final annealed steel sheet may be passed at general line speed in the pickling bath where
the above sulfuric acid is included.
[0163]
( Heat Treatment )
The final annealed steel sheet after the pickling treatment is held in the
temperature range of 700 to 900°C for 10 to 60 seconds in the mixed atmosphere of
nitrogen and hydrogen where the dew point is 10 to 30°C and the hydrogen concentration
15 is 0 to 4 volume%. By the heat treatment, the layer including mainly iron oxides, the
20
Si -Cr included oxide layer, and the Si included oxide layer are formed on the surface of
the final annealed steel sheet. The steel sheet after the heat treatment becomes the steel
substrate which satisfies the above conditions (I) to (III).
[0164]
Herein, the mixed atmosphere of nitrogen and hydrogen where the hydrogen
concentration is 0 to 4 volume% represents the atmosphere where the total fraction of
nitrogen and hydrogen in the atmosphere is substantially 100 volume%. When the
above hydrogen concentration is 0 volume%, the nitrogen in the atmosphere becomes
substantially 100 volume%. When the hydrogen concentration in the atmosphere is
58
more than 4 volume%, it is difficult to obtain the grain oriented electrical steel sheet in
which (Feo.s- Feo.os) I Feo.s 2:: 0.35 is satisfied and the maximal point at which the Cr
emission intensity becomes 0.08 to 0.25 times as compared with the Fe emission
intensity is included. Moreover, the operation load for heat treatment facility becomes
5 high, which is not preferable.
[0165]
When the dew point is less than 1 0°C, or when the holding temperature is less
than 700°C, it is difficult to obtain the grain oriented electrical steel sheet having the
above features. When the holding temperature is more than 900°C, the effect is
10 saturated, and the heating cost increases. When the dew point is more than 30°C, it is
difficult to obtain the grain oriented electrical steel sheet having the above features.
[0166]
When the holding time is less than 10 seconds, it is difficult to obtain the grain
oriented electrical steel sheet having the above features. Also, when the holding time is
15 more than 60 seconds, it is difficult to obtain the grain oriented electrical steel sheet
having the above features.
[0167]
The hydrogen concentration is preferably 3 volume% or less. The dew point is
preferably 28°C or less, and more preferably 25°C or less. The holding temperature is
20 preferably 7 50°C or more, and more preferably 800°C or more. The holding time is
preferably 20 seconds or more. The holding time is preferably 50 seconds or less, and
more preferably 40 seconds or less.
[0168]
Herein, in the embodiment, it is preferable that the oxygen is not included in the
59
atmosphere for the heat treatment. In the embodiment, the steel piece includes Cr as the
base element. When the steel piece includes the above amount of Cr and the above
production conditions are satisfied, it is possible to obtain the grain oriented electrical
steel sheet in which (Feo.s - Feo.os) I Feo.s 2:: 0.35 is satisfied and the maximal point at
5 which the Cr emission intensity becomes 0.08 to 0.25 times as compared with the Fe
emission intensity is included. When the atmosphere for the heat treatment includes the
oxygen, it is difficult to obtain the grain oriented electrical steel sheet having the above
features. Even when the atmosphere for the heat treatment includes the oxygen as
impurity, it is preferable that the oxygen concentration in the atmosphere is limited to less
10 than 5 volume%. In addition to the above, it is preferable that the dew point is limited
to more than 20°C.
[0169]
< Insulation Coating Forming Process >
The insulation coating forming process (step S 123) is the process of applying
15 the solution for forming the tension-insulation coating to the surface of the oxidized steel
sheet after the oxidizing process and of baking the solution so as to form the
tension-insulation coating with an average thickness of 1 to 3 ~m. In the insulation
coating forming process, the tension-insulation coating may be formed on one sheet
surface or both sheet surfaces of the oxidized steel sheet.
20
25
[0170]
Before applying the solution, the surface of the oxidized steel sheet where the
insulation coating is formed may be subjected to optional pretreatment such as
degreasing treatment with alkaline, pickling treatment with hydrochloric acid, sulfuric
acid, phosphoric acid, and the like. The pretreatment may not be conducted.
[0171]
60
The conditions for forming the tension-insulation coating are not particularly
limited, and known conditions may be adopted. Moreover, the tension-insulation
coating may mainly include inorganics and may further include organics. For instance,
the tension-insulation coating may mainly include at least one of metal chromate, metal
5 phosphate, colloidal silica, Zr compound, Ti compound, and the like as the inorganics,
and fine particles of organic resin may be dispersed in the tension-insulation coating.
From the viewpoint of reducing the environmental loading during producing, the
tension-insulation coating may be produced from starting material such as metal
phosphate, coupling agents of Zr or Ti, carbonates thereof, ammonium salts thereof.
10 [0172]
< Other Processes >
( Flattening Annealing Process )
Following the insulation coating forming process, the flattening annealing may
be conducted for straightening. By conducting the flattening annealing for the grain
15 oriented electrical steel sheet after the insulation coating forming process, it is possible to
favorably reduce the iron loss characteristics.
[0173]
( Magnetic Domain Refining Process)
The magnetic domain refining treatment may be conducted for the produced
20 grain oriented electrical steel sheet. Herein, the magnetic domain refining treatment is
the treatment such that the laser beam which refines the magnetic domain is irradiated to
the surface of the grain oriented electrical steel sheet or the groove is formed on the
surface of the grain oriented electrical steel sheet. By conducting the magnetic domain
refining treatment, it is possible to favorably reduce the magnetic characteristics.
25
61
Examples
[0174]
Hereinafter, the effects of an aspect of the present invention are described in
detail with reference to the following examples. However, the condition in the
5 examples is an example condition employed to confirm the operability and the effects of
the present invention, so that the present invention is not limited to the example condition.
The present invention can employ various types of conditions as long as the conditions
10
do not depart from the scope of the present invention and can achieve the object of the
present invention.
[0175]
(Example 1)
A steel slab was heated to 1350°C, and then were hot-rolled to obtain the hot
rolled steel sheets having the average thickness of 2.3 mm, herein the steel slab including
0.081 mass% of C, 3.3 mass% of Si, 0.083 mass% of Mn, 0.022 mass% of S (0.022
15 mass% of S+Se), 0.025 mass% of sol.Al, 0.04 mass% of Cr, 0.008 mass% of N, 0.0025
mass% of Bi, and the balance consisting of Fe and impurities.
[0176]
The obtained hot rolled steel sheets were annealed at 11 00°C for 120 seconds,
and then were pickled. The steel sheets after pickling were cold-rolled to obtain the
20 cold rolled steel sheets having the average thickness of 0.23 mm. The obtained cold
rolled steel sheets were decarburization-annealed.
[0177]
Subsequently, the annealing separator was applied and dried. In the annealing
separator, MgO and Ah03 of 95 mass% in total as percent solid were included, the
25 mixing ratio of MgO and Ah03 was 50% : 50% in mass%, and BiOCl of 5 mass% as
62
compared with the total amount of MgO and Ah03 was included. Thereafter, the final
annealing was conducted at 1200°C for 20 hours.
[0178]
The redundant annealing separator is removed by water-washing from the
5 obtained final annealed steel sheets. In the steel sheets, the glass film (forsterite film)
was not formed when confirmed by X-ray diffraction method.
[0179]
The steel sheets after removing the redundant annealing separator by
water-washing were subjected to the pickling treatment using the sulfuric acid whose
10 concentration was 5 mass% and whose temperature was 70°C. Thereafter, the heat
treatment was conducted at 850°C for 10 seconds in (A) 100% of N2 and 30°C of dew
point and (B) atmospheric air (specifically 21% of02 and 79% ofN2) and 10°C of dew
point.
15
20
[0180]
The aqueous solution which mainly included aluminum phosphate and colloidal
silica was applied to the steel sheets after the oxidizing process, the solution was baked at
850°C for 1 minute, and thereby, the tension-insulation coating whose coating weight
was 4.5 g/m2 per one side was formed on the surface of the steel sheets.
[0181]
The base steel sheets of the grain oriented electrical steel sheets were chemically
analyzed on the basis of the above method. The any steel sheets included, as the
chemical composition, by mass%, 0.002% or less of C, 3.3% of Si, 0.083% of Mn,
0.005% or less of S (0.005% or less of S+Se), 0.005% or less of sol.Al, 0.04% of Cr,
0.005% or less of N, 0.0001% of Bi, and the balance consisting of Fe and impurities.
63
[0182]
For the obtained grain oriented electrical steel sheets of two types (A) and (B),
the GDS analysis, the magnetic characteristics, and the coating adhesion were evaluated.
[0183]
5 < GDS Analysis>
On the basis of the above method, for the surface of the oxidized steel sheet after
the oxidizing process and the surface of the grain oriented electrical steel sheet after
forming the tension-insulation coating, the glow discharge spectroscopy was conducted
using GDA750 produced by Rigaku Corporation. The measurement elements were 0,
10 Cr, Si, and Fe for the oxidized steel sheet and 0, Al, Cr, Si, P, and Fe for the grain
oriented electrical steel sheet. The obtained GDS depth profile was evaluated.
[0184]
< Magnetic Characteristics >
A test piece with a length of 300 mm parallel to the rolling direction and a width
15 of 60 mm was subjected to stress relief annealing at 800°C for 2 hours in nitrogen
atmosphere, and was subjected to the magnetic domain refining treatment by the laser
irradiation. Eight pieces of the test piece were prepared. The magnetic flux density
B8 in the rolling direction (unit : T) (magnetic flux density in 800A/m) and the iron loss
W17 /50 (unit : W /kg) (iron loss when excited to 1.7T at 50Hz) were evaluated on the
20 basis of the method regulated by JIS C 2556: 2015, using the test pieces. The average
ofB8, the average ofW17/50, and the standard deviation ofW17/50 were calculated
using the results of the eight test pieces.
[0185]
< Adhesion of Insulation Coating >
25 The test piece whose longitudinal direction corresponded to the rolling direction
64
was taken from the obtained grain oriented electrical steel sheets, and the bend tests of
bending diameter

A test piece was taken from the obtained grain oriented electrical steel sheet, and
15 the average thickness of the tension-insulation coating was measured by the above
method.
[0188]
In regard to the appearance of the obtained grain oriented electrical steel sheet,
the steel sheets of the condition (A) became dark brown, and the steel sheets of the
20 condition (B) became light gray.
25
[0189]
Moreover, the adhesion of the insulation coating of both steel sheets of the
conditions (A) and (B) was Grade A. The average thickness of the tension-insulation
coating of both steel sheets of the conditions (A) and (B) was 3.0 ~m.
[0190]
65
Moreover, in regard to GDS depth profile, the oxidized steel sheets of the
condition (A) satisfied the above conditions (I) to (III). The grain oriented electrical
steel sheets of the condition (A) satisfied (Feo.s - Feo.os) I Feo.s 2:: 0.35, and included the
maximal point at which the Cr emission intensity becomes 0.08 to 0.25 times as
5 compared with the Fe emission intensity.
On the other hand, the oxidized steel sheets of the condition (B) did not satisfy
the above conditions (I) to (III). The grain oriented electrical steel sheets of the
condition (B) did not satisfy (Feo.s- Feo.os) I Feo.s 2:: 0.35, and did not include the maximal
point at which the Cr emission intensity becomes 0.08 to 0.25 times as compared with
10 the Fe emission intensity.
15
[0191]
Moreover, in regard to the magnetic characteristics, the grain oriented electrical
steel sheets of the condition (A) showed excellent standard deviation of W17 /50 as
compared with the grain oriented electrical steel sheets of the condition (B).
[0192]
(Example 2)
A steel slab A (steel piece A) and a steel slab B (steel piece B) were heated to
1350°C, and then were hot-rolled to obtain the hot rolled steel sheets having the average
thickness of 2.3 mm, herein the steel slab A including 0.082 mass% of C, 3.3 mass% of
20 Si, 0.082 mass% ofMn, 0.023 mass% of S (0.023 mass% of S+Se), 0.025 mass% of
sol.Al, 0.05 mass% of Cr, 0.008 mass% of N, and the balance consisting of Fe and
impurities, and the steel slab B including. 0.081 mass% of C, 3.3 mass% of Si, 0.083
mass% of Mn, 0.022 mass% of S (0.022 mass% of S+Se), 0.025 mass% of sol.Al, 0.04
mass% of Cr, 0.008 mass% of N, 0.0025 mass% of Bi, and the balance consisting of Fe
25 and impurities.
66
[0193]
The obtained hot rolled steel sheets were annealed at 11 00°C for 120 seconds,
and then were pickled. The steel sheets after pickling were cold-rolled to obtain the
cold rolled steel sheets having the average thickness of 0.23 mm. The obtained cold
5 rolled steel sheets were decarburization-annealed.
[0194]
Subsequently, the annealing separator was applied and dried. In the annealing
separator, MgO and Ah03 of 95 mass% in total as percent solid were included, the
mixing ratio of MgO and Ah03 was 50% : 50% in mass% (1 :1 as mass ratio), and
10 BiOCl of 5 mass% as compared with the total amount of MgO and Ah03 was included.
Thereafter, the final annealing was conducted at 1200°C for 20 hours.
[0195]
The redundant annealing separator is removed by water-washing from the
obtained final annealed steel sheet. In any steel sheets, the glass film (forsterite film)
15 was not formed when confirmed by X-ray diffraction method.
[0196]
The steel sheets after removing the redundant annealing separator by
water-washing were subjected to the pickling treatment using the sulfuric acid whose
temperature was 70°C and whose concentration was shown in the following Table 1.
20 Thereafter, the heat treatment was conducted by changing atmosphere, dew point,
temperature, and time.
[0197]
[Table 1]
Ul
~ 00 r.J..J. .. Ul 1-"' ~ 0 ......
rJJ n 0 ..j:::.. n ~ (.)) ~
8' ~
~ 0 (fq
~ 0 ........ '""! rJJ
0"' 1--' SN 1--' ~ 0"' 1--'
"'d (D \0 (D \0 s "'d ~ 00 0" \0 "'d 1-"' ,.0 L........J ...... ...... ~ L........J (D ::s (D ~ rJJ '""! (D ~ 0.. (D
rJJ 0::s """'" """'" 0 ~(D 0 ~ """'" (D
~ """'" (D rJJ
0"' rJJ
(D
1-"' r.J..J. .. ::s
0.. 0.. (D 0 1-"'
rJJ
"""'" rJJ 0"' (D ~
0"' """'" """'"
(D
~ (D (D ...... (D 0
(D
~ '""! r"J""J'" (D 1-"' ::s rJJ 0" rJJ
~ 0 ....., 8' :< 0"'
(D """'" '""! 0"'
"""'" s (D ...... 0"' 0"' """'" n
rJJ 0"'
(D
(D (D
(fq 0.. """'" ~ '""! (D ::::P s
0 ::s (D ~
~ ...... ::s rJJ '""! ......
::s ...... ::s
0 "0"""'"' 0::s "0"""'"' 1-"' '""! (D (D "< ...... I ......
rJJ ...... (D 0 ::s
~ ::s ::s >< n rJJ ...... """'" '""! 1-"'
~ 0.. ~
(D ~ 1-"' ...... 0.. n ~ N 0.. (D (D ...... :..:.s.. . (D 1-"' 0.. (D 0 0::s (fq
n ....., ~
"""'" """'" n "'d '""! ~
0"' 0 '""! s ......
n 0 (D ~ n ...... """'" ~
"""'" ...... 1-"' (D ::s
(D ::s rJJ rJJ rJJ ~ """'" (fq rJJ s (D """'" ~
"'d ~ """'" "'d
(D
1-"' ...... 0"'
0"' 0"' rJJ (nD (D 0
0"' (D rJJ rJJ 0
(D (D 0 rJJ 1-"' "'d (D """'" n ~ 0"' 0 """'" ~
rJJ ......
~ ~ 0 (D "..".".'".. ::s
~
(D '""! ::s
(D (fq ~ ::s
n ~ ~ 0..
0"' rJJ n (D (D ...... 0" 0
s (fq 1-"' ~ 1-"' 0"' 0 ......
n """'" (D ......
~ 0.. 0..
~ 1-"'
~ 1-"'
1-"'
"< """'"
No. STEEL TYPE
2-1 A
2-2 A
2-3 A
2-4 A
2-5 A
2-6 A
2-7 A
2-8 A
2-9 A
2-10 A
2-11 A
2-12 A
2-13 A
2-14 B
2-15 B
2-16 B
2-17 B
2-18 B
2-19 B
2-20 B
2-21 B
2-22 B
2-23 B
2-24 B
2-25 B
2-26 B
PRODUCTION CONDITIONS
OXIDIZING PROCESS
WASHING PICKLING HEAT TREATMENT
WASHING CONCENTRATION TEMPERATURE ATMOSPHERE
METHOD OF NITROGEN HYDROGEN
SULFURIC ACID CONCENTRATION CONCENTRATION
mass% oc volume% volume%
Water Washing 5 70 100 0
Water Washing 5 70 96 4
Water Washing 5 70 100 0
Water Washing 15 70 100 0
Water Washing 15 70 96 4
Water Washing 15 70 100 0
Water Washing 3 70 100 0
Water Washing 15 70 100 0
Water Washing 15 70 80 20
Water Washing 15 70 100 0
Water Washing 15 70 80 20
Water Washing 15 70 100 0
Water Washing 25 70 100 0
Water Washing 5 70 100 0
Water Washing 5 70 96 4
Water Washing 5 70 100 0
Water Washing 15 70 100 0
Water Washing 15 70 96 4
Water Washing 15 70 100 0
Water Washing 3 70 100 0
Water Washing 15 70 100 0
Water Washing 15 70 80 20
Water Washing 15 70 100 0
Water Washing 15 70 80 20
Water Washing 15 70 100 0
Water Washing 25 70 100 0
OXYGEN DEW POINT
CONCENTRATION
volume% oc
0 30
0 30
0 30
0 20
0 20
0 20
0 -30
0 20
0 10
0 -30
0 10
0 45
0 30
0 30
0 30
0 30
0 20
0 20
0 20
0 -30
0 20
0 10
0 -30
0 10
0 40
0 30
TEMPERATURE
oc
800
850
800
680
800
840
720
800
800
850
800
800
680
800
850
800
680
800
840
720
800
800
850
800
800
680
TIME
seconds
5
15
40
20
20
20
80
30
30
30
80
30
20
5
15
40
20
20
20
80
30
30
30
80
30
20
0-..)
68
analyzed on the basis of the above method. The steel sheets made from the steel slab A
included, as the chemical composition, by mass%, 0.002% or less of C, 3.3% of Si,
0.082% of Mn, 0.005% or less of S (0.005% or less of S + Se), 0.005% or less of sol.Al,
0.05% of Cr, 0.005% or less of N, and the balance consisting of Fe and impurities. The
5 steel sheets made from the steel slab B included, as the chemical composition, by mass%,
0.002% or less of C, 3.3% of Si, 0.083% Mn, 0.005% or less of S (0.005% or less of S +
Se), 0.005% or less of sol.Al, 0.04% of Cr, 0.005% or less of N, 0.0001 mass% of Bi, and
the balance consisting of Fe and impurities.
[0200]
10 < Evaluation >
15
The magnetic characteristics, the GDS analysis, the coating adhesion, and the
like were evaluated. The evaluation methods were as follows.
[0201]
( Magnetic Characteristics )
A test piece with a length of 300 mm parallel to the rolling direction and a width
of 60 mm was subjected to stress relief annealing at 800°C for 2 hours in nitrogen
atmosphere, and was subjected to the magnetic domain refining treatment by the laser
irradiation. Eight pieces of the test piece were prepared. The magnetic flux density
B8 in the rolling direction (unit : T) (magnetic flux density in 800A/m) and the iron loss
20 W17 /50 (unit : W /kg) (iron loss when excited to 1.7T at 50Hz) were evaluated on the
basis of the method regulated by JIS C 2556: 2015, using the test pieces. The average
ofB8, the average ofW17/50, and the standard deviation ofW17/50 were calculated
using the results of the eight test pieces.
Herein, in regard to the steel type A, when the average of B8 was 1.90 T or more,
25 when the average of W17 /50 was 0. 700 W /kg or less, and when the standard deviation of
5
69
W17 /50 was 0.020 W /kg or less, it was judged to as acceptable. In regard to the steel
type B, when the average ofB8 was 1.90 Tor more, when the average ofW17/50 was
0.650 W /kg or less, and when the standard deviation of W17 /50 was 0.020 W /kg or less,
it was judged to as acceptable.
[0202]
( GDS Analysis)
On the basis of the above method, for the surface of the oxidized steel sheet after
the oxidizing process and the surface of the grain oriented electrical steel sheet after
forming the tension-insulation coating, the analysis was conducted under conditions such
10 that output was 30W, Ar pressure was 3 hPa, measurement area was 4 mm diameter, and
measurement time was 100 seconds in high frequency mode using GDA750 produced by
Rigaku Corporation. The measurement elements were 0, Cr, Si, and Fe for the oxidized
steel sheet and 0, Al, Cr, Si, P, and Fe for the grain oriented electrical steel sheet. By
the obtained GDS depth profile, it was confirmed whether or not the oxidized steel sheets
15 satisfied the above conditions (I) to (III), and whether or not the grain oriented electrical
steel sheets satisfied (Feo.s - Feo.os) I Feo.s 2:: 0.35 and included the maximal point at which
the Cr emission intensity becomes 0.08 to 0.25 times as compared with the Fe emission
intensity.
[0203]
20 ( Adhesion of Tension-Insulation Coating )
The test piece whose longitudinal direction corresponded to the rolling direction
was taken from the obtained grain oriented electrical steel sheets, and the bend tests of
bending diameter

0 rJJ N n 0 I-"' (D ~
~
CONDITION CONDITION CONDITION (Feo.5-Feo.o5) RATIO AVERAGE 8a w1115o w1115o ~20 ~10
No. STEEL TYPE (I) (II) (Ill) /Feo.5 OF THICKNESS BENDING BENDING
PRESENCE RATIO RATIO OF STANDARD
OF OF OF Cr EMISSION INSULATION
AVERAGE AVERAGE
DEVIATION
PLATEAU Cr EMISSION Si EMISSION INTENSITY COATING
"< REGION INTENSITY INTENSITY j.lm T W/kg W/kg
rJJ
0"'
0
2-1 A Presence 0.008 0.186 0.21 0.04 2.0 1.925 0.736 0.048 c c COMPARATIVE EXAMPLE
~ 2-2 A Presence 0.021 0.101 0.45 0.23 2.0 1.930 0.691 0.017 A A INVENTIVE EXAMPLE
:..:.s.. . 2-3 A Presence 0.022 0.081 0.56 0.21 2.0 1.931 0.692 0.016 A A INVENTIVE EXAMPLE
::s
"""'"
2-4 A Presence No Peak 0.051 0.23 No Peak 2.0 1.929 0.725 0.045 c c COMPARATIVE EXAMPLE
0"'
(D 2-5 A Presence 0.017 0.064 0.68 0.23 2.0 1.931 0.692 0.015 A A INVENTIVE EXAMPLE
~ 2-6 A Presence 0.015 0.092 0.62 0.18 2.0 1.932 0.692 0.018 A A INVENTIVE EXAMPLE
0"
I-"'
(D 2-7 A Presence 0.008 0.245 0.23 0.04 2.0 1.920 0.748 0.041 c c COMPARATIVE EXAMPLE
rJJ 2-8 A Presence 0.018 0.078 0.57 0.23 2.0 1.932 0.699 0.018 A A INVENTIVE EXAMPLE 1--'
Ro
N
2-9 A Presence 0.013 0.314 0.18 0.04 2.0 1.915 0.762 0.047 A A COMPARATIVE EXAMPLE
2-10 A Presence 0.011 0.246 0.15 0.04 2.0 1.921 0.746 0.050 A A COMPARATIVE EXAMPLE -..)
1--'
r.J..J. .. 2-11 A Presence 0.013 0.501 0.16 0.04 2.0 1.921 0.748 0.041 c c COMPARATIVE EXAMPLE
::s n 2-12 A Presence 0.031 0.081 0.57 0.28 2.0 1.922 0.734 0.021 c c COMPARATIVE EXAMPLE
(D
"""'" 2-13 A Presence No Peak 0.051 0.23 No Peak 2.0 1.921 0.746 0.042 c c COMPARATIVE EXAMPLE
0"'
(D 2-14 8 Presence 0.008 0.193 0.22 0.04 2.0 1.951 0.679 0.044 c c COMPARATIVE EXAMPLE
0
.>.<.. .. 2-15 8 Presence 0.023 0.112 0.46 0.22 2.0 1.970 0.621 0.017 A A INVENTIVE EXAMPLE
0........ 2-16 8 Presence 0.023 0.081 0.58 0.23 2.0 1.971 0.620 0.015 A A INVENTIVE EXAMPLE
N.... ..
::s 2-17 8 Presence No Peak 0.201 0.21 No Peak 2.0 1.956 0.651 0.047 c c COMPARATIVE EXAMPLE
(fq 2-18 8 Presence 0.018 0.061 0.69 0.24 2.0 1.971 0.622 0.018 A A INVENTIVE EXAMPLE n
0 ::s 2-19 8 Presence 0.015 0.089 0.61 0.17 2.0 1.973 0.621 0.014 A A INVENTIVE EXAMPLE
0........ 2-20 8 Presence 0.008 0.233 0.24 0.04 2.0 1.953 0.662 0.043 c c COMPARATIVE EXAMPLE
"..".".'"..
0 2-21 8 Presence 0.021 0.081 0.55 0.22 2.0 1.973 0.621 0.017 A A INVENTIVE EXAMPLE
::s
rJJ 2-22 8 Presence 0.015 0.325 0.19 0.03 2.0 1.943 0.689 0.047 A A COMPARATIVE EXAMPLE
~
(D 2-23 8 Presence 0.016 0.255 0.16 0.04 2.0 1.944 0.686 0.048 A A COMPARATIVE EXAMPLE
'""!
(D 2-24 8 Presence 0.015 0.366 0.15 0.03 2.0 1.949 0.673 0.043 c c COMPARATIVE EXAMPLE
2-25 8 Presence 0.033 0.092 0.58 0.29 2.0 1.951 0.658 0.043 c c COMPARATIVE EXAMPLE
2-26 8 Presence No Peak 0.179 0.22 No Peak 2.0 1.948 0.675 0.043 c c COMPARATIVE EXAMPLE
72
satisfied in the test numbers 2-2,2-3,2-5,2-6,2-8,2-15,2-16,2-18,2-19, and 2-21, the
oxidized steel sheets satisfied the above conditions (I) to (III), and the grain oriented
electrical steel sheets satisfied (Feo.s - Feo.os) I Feo.s 2:: 0.35 and included the maximal
point at which the Cr emission intensity becomes 0.08 to 0.25 times as compared with
5 the Fe emission intensity. As a result, both magnetic characteristics and coating
adhesion were excellent.
10
Moreover, since the chemical compositions of the steel slabs were favorable in
the test numbers 2-15, 2-16, 2-18, 2-19, and 2-21 among the above test numbers, the
magnetic characteristics were further excellent.
[0209]
On the other hand,
since the holding time for oxidizing was shorter in the test number 2-1, the
holding temperature for oxidizing was lower in the test number 2-4, and the dew point
for oxidizing was lower and the holding time for oxidizing was longer in the test number
15 2-7, the coating adhesion and the magnetic characteristics were inferior.
Since the atmosphere for oxidizing was out of the range described above in the
test number 2-9 and the dew point for oxidizing was lower in the test number 2-10, the
magnetic characteristics were particular! y inferior.
Since the atmosphere for oxidizing was out of the range described above and the
20 holding time for oxidizing was longer in the test number 2-11, the coating adhesion and
the magnetic characteristics were inferior.
Since the dew point for oxidizing was higher in the test number 2-12, the
coating adhesion was particularly inferior.
Since the concentration for pickling was higher and the temperature for
25 oxidizing was lower in the test number 2-13, the coating adhesion and the magnetic
73
characteristics were inferior.
Since the holding time for oxidizing was shorter in the test number 2-14, the
holding temperature for oxidizing was lower in the test number 2-17, and the dew point
for oxidizing was lower and the holding time for oxidizing was longer in the test number
5 2-20, the coating adhesion and the magnetic characteristics were inferior.
Since the atmosphere for oxidizing was out of the range described above in the
test number 2-22 and the dew point for oxidizing was lower in the test number 2-23, the
magnetic characteristics were particular! y inferior.
Since the atmosphere for oxidizing was out of the range described above and the
10 holding time for oxidizing was longer in the test number 2-24, the coating adhesion and
the magnetic characteristics were inferior.
Since the dew point for oxidizing was higher in the test number 2-25, the
coating adhesion was particularly inferior.
Since the concentration for pickling was higher and the temperature for
15 oxidizing was lower in the test number 2-26, the coating adhesion and the magnetic
characteristics were inferior.
[0210]
(Example 3)
Steel slabs (steel pieces) with chemical compositions shown in the following
20 Table 3 were heated to 1380°C, and then were hot-rolled to obtain the hot rolled steel
sheets having the average thickness of 2.3 mm. Some steels were cracked, and thus
could not be subjected to subsequent processes.
[0211]
[Table 3]
Ul
".0."."."'"..' ".'.d... . ~
n n (D
g c: '""!
...... (D
(D ::s ~
rJJ (fq ::s
rJJ
0 ~
::s
(D ~ ....., (D ~
9
'""! 1-"' 0"'
(D (D (D
N n 0.. 0"'
u:; 0 ~ 0
~
1-"' """'" """'"
0.. 1--' '""!
I 1--' 0
'""!
0 N
1-"'
1-"'
1-"' 0 (D
1-"'
(D
0 0..
\./). 0.. n rJJ
0 """'" 8' """'"
s 0
(D
(D
(D 0
'""! 1-"'
rJJ
0" 1--' rJJ
"""'"
"""'" N 0"'
(D
~ 0 (D ......
(D ::s (D
1-"'
rJJ """'"
rJJ """'"
(D
rJJ
~
0"' n ~
(D 0
(D n ::s 0"'
'""! 0..
......
(D 0
n
1-"' ~rJJ 0"'
STEEL TYPE
A-1
A-2
A-3
A-4
A-5
A-6
A-7
n 0..
'""! '""!
~ n
~ ::s 0
n 0 0.. ~
@ 1-"'
1-"' """'"
1-"'
(D 0..
0.. 0..
0"'
(D 0"
0.. rJJ ::s (D
~ (""D"'" ~
rJJ
'""! (D ~ ......
::s 1-"' (D 3':
rJJ
'""!
(fq 0"'
(D (D
n (D "'d n
0 (D ...... """'"
1-"' """'"
n (D
0.. rJJ ~
0..
'""! 0"'
1-"' """'" (D 0
0 ~ p..
1-"' < rJJ
1...-."..' ...... ~
::s ::s 0"
qo (fq ~ rJJ
"""'" 0"'
(D
§ 0"' (D
,.0
(D ~
0.. ~
rJJ (D
"""'"
"""'" < (D ::s
0"' (D
(D """'"
~ '""!
1-"' "'d
rJJ ~ rJJ
'""!
n (fq 0"' 0
0
(D (D n
(D
(D
~ """'"
rJJ
1-"'
rJJ rJJ
(D
A-8
A-9
A-10
A-11
A-12
A-13
A-14
A-15
A-16
A-17
A-18
A-19
A-20
A-21
A-22
0.. ~
::s ::::P
rJJ
0 (D
"""'"
'""!
A-23
A-24
PRODUCTION COND!T!ONS
CHEMICAL COMPOSITION OF SLAB (STEEL PIECE) (UNIT: mass%. BALANCE CONSISTING OF Fe AND IMPUR!T!ES)
c Si Mn s Se s soi.AI
+Se
0.079 3.31 0.080 0.022 0.001 0.023 0.025
0.078 3.51 0.077 0.002 0.051 0.053 0.024
0.082 3.31 0.080 0.001 0.023 0.024 0.025
0.082 3.31 0.080 0.020 0.006 0.026 0.025
0.081 3.22 0.075 0.021 0.002 0.023 0.025
0.080 3.32 0.080 0.019 0.003 0.022 0.026
0.079 3.31 0.080 0.022 0.001 0.023 0.025
0.078 3.51 0.077 0.001 0.018 0.019 0.024
0.079 3.22 0.080 0.019 0.003 0.022 0.025
0.080 3.31 0.080 0.001 0.022 0.023 0.025
0.085 3.31 0.080 0.022 0.001 0.023 0.025
0.071 4.05 0.081 0.019 0.051 0.070 0.025
0.071 2.41 0.081 0.019 0.001 0.020 0.025
0.008 3.28 0.075 0.022 0.006 0.028 0.021
0.209 3.15 0.051 0.021 0.006 0.027 0.031
0.061 3.31 0.081 0.012 0.003 0.015 0.009
0.061 3.29 0.082 0.015 0.003 0.018 0.075
0.072 3.19 0.008 0.051 0.001 0.052 0.018
0.073 3.18 1.010 0.051 0.001 0.052 0.015
0.071 3.25 0.081 0.003 0.001 0.004 0.025
0.071 3.19 0.051 0.095 0.001 0.096 0.019
0.085 3.31 0.082 0.052 0.002 0.054 0.023
0.085 3.31 0.052 0.052 0.002 0.054 0.023
0.079 3.31 0.080 0.022 0.001 0.023 0.025
N Bi Te
0.008 - -
0.008 - -
0.008 0.0025 -
0.008 0.0025 -
0.009 - 0.0015
0.008 - -
0.009 0.0026 0.0005
0.008 - 0.0018
0.009 0.0021 -
0.008 0.0018 0.0018
0.008 0.0141 0.0018
0.008 - -
0.008 - -
0.008 - -
0.006 - -
0.009 - -
0.009 - -
0.008 - -
0.009 - -
0.008 - -
0.008 - -
0.023 - -
0.002 - -
0.008 - -
Pb
-
-
-
-
-
0.0015
-
0.0011
0.0015
0.0018
0.0012
-
-
-
-
-
-
-
-
-
-
-
-
-
Cr
0.05
0.03
0.04
0.12
0.13
0.25
0.03
0.05
0.03
0.03
0.03
0.03
0.03
0.03
0.03
0.03
0.03
0.03
0.03
0.03
0.03
0.03
0.03
-
-..)
..j:::..
75
be subjected to subsequent processes. The steel sheets which could be subjected to
subsequent processes were decarburization -annealed.
[0212]
Subsequently, the annealing separator was applied and dried. In the annealing
5 separator, MgO and Ah03 of 94 mass% in total as percent solid were included, the
mixing ratio of MgO and Ah03 was 50% : 50% in mass% (1 :1 as mass ratio), and
BiOCl of 6 mass% as compared with the total amount of MgO and Ah03 was included.
Thereafter, the final annealing was conducted at 1200°C for 20 hours.
10
[0213]
The redundant annealing separator is removed by water-washing from the
obtained final annealed steel sheet. In any steel sheets, the glass film (forsterite film)
was not formed when confirmed by X-ray diffraction method.
[0214]
The steel sheets after removing the redundant annealing separator by
15 water-washing were subjected to the pickling treatment using the sulfuric acid whose
temperature was 70°C and whose concentration was 10%. Thereafter, the heat
treatment was conducted by holding under conditions such as 100% of nitrogen, 30°C of
the dew point, 800°C of the temperature, and 20 seconds of time. Herein, in the test
number 3-25, the heat treatment was not conducted, and the test number 3-25 was as
20 pickled.
25
[0215]
The GDS analysis was conducted by the method which is the same as that in
Example 2 for the steel sheets after the oxidizing process. The steel sheets except for
the test numbers 3-12, 3-21, and 3-24 satisfied the above conditions (I) to (III).
[0216]
5
76
Subsequently, the aqueous solution which mainly included aluminum phosphate
and colloidal silica was applied, the solution was baked at 850°C for 1 minute, and
thereby, the tension-insulation coating whose coating weight was 4.5 g/m2 per one side
was formed on the surface of the test piece.
[0217]
The base steel sheets of the grain oriented electrical steel sheets were chemically
analyzed on the basis of the above method. The chemical compositions are shown in
Table 4. In regard to Table 3 and Table 4, the element which is expressed in blanc or "-"
in the tables indicates the element in which the purposeful control is not conducted for
10 the amount thereof during production.
[0218]
[Table 4]
1tTI
< PRODUCT! ON RESULTS
~
I-"'
~ CHEMICAL COMPOSITION OF GRAIN ORIENTED ELECTRICAL STEEL SHEET (UNIT: mass%. BALANCE CONSISTING OF Fe AND IMPURITIES)
~ ~ "..".".'".. 0
0"' 0 N (D ::s 1--'
c Si Mn s Se s soi.AI N Bi Te Pb Cr
No. STEEL TYPE +Se s v :::s
~
(fq ::s
(D
"..".".'"..
n
n 3-1 A-1 ~0.002 3.31 0.080 ~0.005 ~0.001 ~0.005 ~0.005 ~0.005 - - - 0.05
0"' e; 3-2 A-2 ~0.002 3.51 0.077 ~0.005 ~0.001 ~0.005 ~0.005 ~0.005 - - - 0.03
~ n 3-3 A-3 ~0.002 3.31 0.080 ~0.005 ~0.001 ~0.005 ~0.005 ~0.005 0.0001 - - 0.04
(""D"'"
'""! ...... 3-4 A-4 ~0.002 3.31 0.080 ~0.005 ~0.001 ~0.005 ~0.005 ~0.005 0.0001 - - 0.12
rJJ
"..".".'".. 3-5 A-5 ~0.002 3.22 0.075 ~0.005 ~0.001 ~0.005 ~0.005 ~0.005 - 0.0001 - 0.13
n
~rJJ 3-6 A-6 ~0.002 3.32 0.080 ~0.005 ~0.001 ~0.005 ~0.005 ~0.005 - - 0.0015 0.25
"0"""'"' 3-7 A-7 ~0.002 3.31 0.080 ~0.005 ~0.001 ~0.005 ~0.005 ~0.005 0.0001 0.0001 - 0.03
(D a u \./).
~
3-8 A-8 ~0.002 3.51 0.077 ~0.005 ~0.001 ~0.005 ~0.005 ~0.005 - 0.0001 0.0011 0.05
3-9 A-9 ~0.002 3.22 0.080 ~0.005 ~0.001 ~0.005 ~0.005 ~0.005 0.0001 - 0.0015 0.03
3-10 A-10 ~0.002 3.31 0.080 ~0.005 ~0.001 ~0.005 ~0.005 ~0.005 0.0001 0.0001 0.0018 0.03
-..)
-..)
::s
~ 3-11 A-11 ~0.002 3.31 0.080 ~0.005 ~0.001 ~0.005 ~0.005 ~0.005 0.0001 0.0001 0.0012 0.03
I-"'
"< rJJ 3-12 A-12 - - - - - - - - - - - 0.03 ......
~rJJ 3-13 A-13 ~0.002 2.41 0.081 ~0.005 ~0.001 ~0.005 ~0.005 ~0.005 - - - 0.03
"0"""'"' 3-14 A-14 ~0.002 3.28 0.075 ~0.005 ~0.001 ~0.005 ~0.005 ~0.005 - - - 0.03
(D
n 3-15 A-15 ~0.002 3.15 0.051 ~0.005 ~0.001 ~0.005 ~0.005 ~0.005 - - - 0.03
0
~...... 3-16 A-16 ~0.002 3.31 0.081 ~0.005 ~0.001 ~0.005 ~0.005 ~0.005 - - - 0.03
::s
(fq
3-17 A-17 ~0.002 3.29 0.082 ~0.005 ~0.001 ~0.005 ~0.005 ~0.005 - - - 0.03
~ 3-18 A-18 ~0.002 3.19 0.008 ~0.005 ~0.001 ~0.005 ~0.005 ~0.005 - - - 0.03
0..
0"'
(D
3-19 A-19 ~0.002 3.18 1.010 ~0.005 ~0.001 ~0.005 ~0.005 ~0.005 - - - 0.03
r.J..J. ..
0
3-20 A-20 ~0.002 3.25 0.081 ~0.005 ~0.001 ~0.005 ~0.005 ~0.005 - - - 0.03
F 3-21 A-21 - - - - - - - - - - - 0.03
~ ::s 3-22 A-22 ~0.002 3.31 0.082 ~0.005 ~0.001 ~0.005 ~0.005 ~0.005 - - - 0.03
0..
"""'"
3-23 A-23 ~0.002 3.31 0.052 ~0.005 ~0.001 ~0.005 ~0.005 ~0.005 - - - 0.03
0"'
(D 3-24 A-24 ~0.002 3.31 0.080 ~0.005 ~0.001 ~0.005 ~0.005 ~0.005 - - - -
3-25 A-1 ~0.002 3.31 0.080 ~0.005 ~0.001 ~0.005 ~0.005 ~0.005 - - - 0.05
78
like were evaluated. The evaluation methods for the GDS analysis, the coating
adhesion, and the average coating thickness were the same as those in the Example 2.
The magnetic characteristics were evaluated as follows.
[0220]
5 ( Magnetic Characteristics )
Eight pieces of the test piece with a length of 300 mm parallel to the rolling
direction and a width of 60 mm were prepared. The test pieces were subjected to stress
relief annealing at 800°C for 2 hours in nitrogen atmosphere, and then, the magnetic
characteristics in the rolling direction was evaluated on the basis of the method regulated
10 by JIS C 2556: 2015. When the average of the magnetic flux density B8 (unit: T) was
1.90 Tor more, it was judged to as acceptable. For the steel sheets whose magnetic flux
density B8 was acceptable, the laser beam was irradiated in order to refine the magnetic
domain. For the steel sheets for which the laser beam was irradiated, the average and
the standard deviation of the iron loss W17 /50 (unit : W /kg) (iron loss when excited to
15 1.7T at 50Hz) were evaluated. Herein, when the average of B8 was 1.90 Tor more,
when the average of W17 /50 was 0. 700 W /kg or less, and when the standard deviation of
W17 /50 was 0.020 W /kg or less, it was judged to as acceptable.
20
[0221]
The obtained results are summarized in the following Table 5.
[0222]
[Table 5]
PRODUCTION RESULTS
AFTER OXIDIZING PROCESS
> 0 rJJ N n N
I-"' (D ~
~
STEEL
CONDITION CONDITION CONDITION
No. (I) (II) (III)
TYPE PRESENCE RATIO RATIO
OF OF OF
PLATEAU Cr EMISSION Si EMISSION
"<
rJJ REGION INTENSITY INTENSITY
0"'
0 3-1 A-1 Presence 0.023 0.081
~ ::s 3-2 A-2 Presence 0.021 0.082
......
::s 3-3 A-3 Presence 0.019 0.079
"0"""'"' 3-4 A-4 Presence 0.024 0.091
(D
~
0"
3-5 A-5 Presence 0.025 0.130
3-6 A-6 Presence 0.018 0.123
I-"'
(D
rJJ 3-7 A-7 Presence 0.025 0.065
u:; 3-8 A-8 Presence 0.021 0.078
"0"" '" 3-9 A-9 Presence 0.019 0.089
Ul
3-10 A-10 Presence 0.017 0.121
r.J..J. ..
::s 3-11 A-11 Presence 0.018 0.076
n
(D 3-12 A-12 Presence - -
"0"""'"'
(D 3-13 A-13 Presence 0.023 0.069
n
0"'
3-14 A-14 Presence 0.024 0.073
(D s......
n
3-15 A-15 Presence 0.021 0.089
3-16 A-16 Presence 0.019 0.098
~
I-"' 3-17 A-17 Presence 0.017 0.082
n
0
.§ 3-18 A-18 Presence 0.023 0.114
3-19 A-19 Presence 0.024 0.141
0
r.J..J. .. 3-20 A-20 Presence 0.016 0.138
"..".".'"..
0 3-21 A-21 Presence - -
::s
rJJ 3-22 A-22 Presence 0.022 0.097
0... .., 3-23 A-23 Presence 0.019 0.086
"0"""'"'
(D 3-24 A-24 Presence No Peak 0.071
3-25 A-1 Not Conducted Not Conducted Not Conducted
AFTER INSULATION COATING FORMING PROCESS
(Feo_s-Feo.os) RATIO AVERAGE
/Feo.s OF THICKNESS
Cr EMISSION OF INSULATION
INTENSITY COATING
flm
0.45 0.22 2.0
0.56 0.23 2.0
0.68 0.18 2.0
0.62 0.22 2.0
0.57 0.23 2.0
0.65 0.21 2.0
0.55 0.19 2.0
0.58 0.18 2.0
0.62 0.18 2.0
0.63 0.21 2.0
0.69 0.22 2.0
- - -
0.41 0.11 2.0
0.43 0.15 2.0
0.43 0.21 2.0
0.44 0.15 2.0
0.44 0.15 2.0
0.43 0.21 2.0
0.42 0.11 2.0
0.44 0.11 2.0
- - -
0.44 0.12 2.0
0.42 0.13 2.0
0.42 No Peak 2.0
Not Conducted Not Conducted Not Conducted
EVALUATION RESULTS
MAGNETIC CHARACTERISTICS
Bs W1715o W1715o
STANDARD
AVERAGE AVERAGE
DEVIATION
T W/kg W/kg
1.944 0.699 0.016
1.946 0.700 0.019
1.985 0.618 0.018
1.985 0.622 0.016
1.985 0.622 0.019
1.981 0.628 0.018
1.982 0.629 0.020
1.982 0.628 0.016
1.986 0.615 0.019
1.987 0.610 0.018
1.988 0.608 0.019
- - -
1.681 - -
1.661 - -
1.721 - -
1.691 - -
1.681 - -
1.722 - -
1.701 - -
1.725 - -
- - -
1.722 - -
1.741 - -
1.938 0.721 0.022
1.941 0.711 0.021
ADHESION
¢20
BENDING
A
A
A
A
A
A
A
A
A
A
A
-
A
A
A
A
A
A
A
A
-
A
A
B
c
¢10
BENDING
A
A
A
A
A
A
A
A
A
A
A
-
A
A
A
A
A
A
A
A
-
A
A
B
c
REMARKS
INVENTIVE EXAMPLE
INVENTIVE EXAMPLE
INVENTIVE EXAMPLE
INVENTIVE EXAMPLE
INVENTIVE EXAMPLE
INVENTIVE EXAMPLE
INVENTIVE EXAMPLE
INVENTIVE EXAMPLE
INVENTIVE EXAMPLE
INVENTIVE EXAMPLE
INVENTIVE EXAMPLE
COMPARATIVE EXAMPLE
COMPARATIVE EXAMPLE
COMPARATIVE EXAMPLE
COMPARATIVE EXAMPLE
COMPARATIVE EXAMPLE
COMPARATIVE EXAMPLE
COMPARATIVE EXAMPLE
COMPARATIVE EXAMPLE
COMPARATIVE EXAMPLE
COMPARATIVE EXAMPLE
COMPARATIVE EXAMPLE
COMPARATIVE EXAMPLE
COMPARATIVE EXAMPLE
COMPARATIVE EXAMPLE
-..)
\0
80
base steel sheets were satisfied in the test numbers 3-1 to 3-11, both magnetic
characteristics and adhesion of the insulation coating were excellent.
Moreover, since the chemical compositions of the steel slabs were favorable in
the test numbers 3-3 to 3-11 among the above test numbers, the magnetic characteristics
5 were further excellent.
10
[0224]
On the other hand,
since the Si content was excessive in the test number 3-12, the steel sheet was
fractured during cold rolling.
Since the Si content was insufficient in the test number 3-13, the magnetic
characteristics were inferior.
Since the C content was insufficient in the test number 3-14 and the C content
was excessive in the test number 3-15, the magnetic characteristics were inferior.
Since the sol.Al content was insufficient in the test number 3-16, the magnetic
15 characteristics were inferior.
20
Since the sol.Al content was excessive in the test number 3-17, the steel sheet
was fractured during cold rolling.
Since the Mn content was insufficient in the test number 3-18 and the Mn
content was excessive in the test number 3-19, the magnetic characteristics were inferior.
Since the total amount of Sand Se was insufficient in the test number 3-20, the
magnetic characteristics were inferior.
Since the total amount of Sand Se was excessive in the test number 3-21, the
steel sheet was fractured during hot rolling.
Since theN content was excessive in the test number 3-22, the magnetic
25 characteristics were inferior.
5
10
15
81
Since theN content was insufficient in the test number 3-23, the magnetic
characteristics were inferior.
Since the Cr content was insufficient in the test number 3-24, the adhesion were
inferior.
Since the heat treatment in the oxidizing process was not conducted in the test
number 3-25, the coating adhesion was inferior. In the test number 3-25, the coating
just after being baked had been delaminated even in the frat part except for the bended
part in addition to the bended part. Thus, the GDS analysis could not be conducted.
[0225]
(Example 4)
In regard to steel slabs (steel pieces) with chemical compositions shown in the
following Table 6, the steel slabs of the test numbers 4-1 to 4-7 were heated to 1380°C,
the steel slabs of the test numbers 4-8 to 4-15 were heated to 1350°C, and then were
hot-rolled to obtain the hot rolled steel sheets having the average thickness of 2.3 mm.
[0226]
[Table 6]
~ 0 0"'
(D N
N
0
0" ~
"~..".".'". .
::s
(D
0..
0"'
0
"""'" '""!
0 PRODUCT! ON CONDIT! ONS
1-"'
1-"'
(D CHEMICAL COMPOSITION OF SLAB (STEEL PIECE) (UNIT: mass%, BALANCE CONSISTING OF Fe AND IMPURITIES)
0.. c Si Mn s Se s soi.AI
rJJ
(""D"'" STEEL TYPE +Se
(D
1-"'
rJJ
0"'
(D
(D
r"J""J'"
0... .., B-1 0.082 3.31 0.080 0.001 0.023 0.024 0.025
"""'"
B-2 0.082 3.31 0.080 0.020 0.006 0.026 0.025
0"'
(D B-3 0.081 3.22 0.075 0.021 0.002 0.023 0.025
(""D"'" B-4
rJJ
0.080 3.32 0.080 0.019 0.003 0.022 0.026
":":"s'" B-5 0.079 3.31 0.080 0.022 - 0.022 0.025
~
~
B-6 0.078 3.51 0.077 0.001 0.018 0.019 0.024
B-7 0.079 3.22 0.080 0.022 - 0.022 0.025
(D
'""!
rJJ B-8 0.083 3.31 0.082 0.023 - 0.023 0.025
..j:::.. B-9 0.083 3.31 0.082 0.023 - 0.023 0.025
I
1--'
"0"" '"
..j:::..
I
-..)
~
(D
'""!
(D
§
::s
(D
~
1-"'
(D
0..
N Bi Te Pb
0.008 0.0025 - -
0.008 0.0025 - -
0.009 - 0.0015 -
0.008 - - -
0.009 0.0026 0.0005 -
0.008 - 0.0018 0.0011
0.009 0.0021 - 0.0015
0.008 - - -
0.008 0.0045 - -
Sb Sn
0.021 -
- 0.031
- -
0.043 0.040
- -
- -
- -
- -
- -
Cr
0.04
0.12
0.13
0.25
0.03
0.05
0.03
0.04
0.04
Cu
-
-
0.032
0.046
-
-
-
-
-
00
N
83
at 1120°C for 120 seconds, the obtained hot rolled steel sheets of the test numbers 4-8 to
4-15 were annealed at 1100°C for 120 seconds, and then were pickled. The steel sheets
after pickling were cold-rolled to obtain the cold rolled steel sheets having the average
thickness of 0.23 mm. The obtained cold rolled steel sheets were
5 decarburization -annealed.
[0228]
Subsequently, the final annealing was conducted under conditions shown in the
following Table 7. In the Table 7, the amount of main materials in the annealing
separator is shown as percent solid. Moreover, the amount of the bismuth chloride is
10 shown as the amount compared with the total amount of MgO and Ah03.
[0229]
[Table 7]
84
-= -= -= -= -= Q.) Q.) Q.) Q.) Q.)
c.!:l +--' +--' +--' +--' +--'
= 0 0 0 0 0 :::;;:;: :::J :::J :::J :::J :::J > -= -= -= -= -= = _J c c c c c :::;;:;: i:i: c.0..: :> c.0..: :> c.0..: :> c.0..: :> c.0..: :> L.J..J c:::: +--' +--' +--' +--' +--'
0 0 0 0 0 = = = = =
L.J..J ..__
:::;;:;: :::J 0 0 0 0 0
j:::: -0= C'oJ C'oJ C'oJ C'oJ C'oJ
L.J..J c:::: !=;;;;: 0 0 0 0 0
c:::: 9 0 0 0 0 0
L.J..J C'oJ C'oJ C'oJ C'oJ C'oJ c... .,...... .,...... .,...... .,...... .,......
:::;;:;:
L.J..J
1--
1-- e,--!:;2 == en
= en CD CD CD LO r--- co L.J..J :::;;:;: E = - - - (") (") = L.J..J () () () 1=-- >c..-. 0 0 0 0 0
:::;;:;: 1-- co co co co co (/.)
C5
0
(")·-
0 0~ .,...... .,...... .,...... .,...... .,......
b.O N "-- .. .. .. .. ..
:::2: <( eenn .,...... .,...... .,...... .,...... .,......
'-.... co
E
(/.) = 1-- ~ c:::: = ef2- = = = ~ en
"""" """" """"
LO C'?
j:::: en !;;;;: = = co 0") 0") 0") 0") 0")
C5 :::;;:;: c.!:l c:::: L.J..J - 0 = - .,...... C'oJ C'?
""""
1-- LO
_J I I I I I
L.J..J co co co co co L.J..J
1--
(/.)
0 .,...... C'oJ C'?
""""
LO
z I I I I I
"""" """" """" """" """"
[0230]
-= -= -= -= Q.) Q.) Q.) Q.) --o --o +--' +--' +--' +--'
Q) Q) 0 0 0 0
t) t) :::J :::J :::J :::J -= -= -= -= --::o:l --::o:l c c c c c c 0 0 0 0 c...::> c...::> c...::> c...::> 0 0
0 0 +--' +--' +--' +--'
0 0 0 0 = = = =
0 0 0 0 0 0
C'oJ C'oJ C'oJ C'oJ C'oJ C'oJ
0 0 0 0 0 0
0 0 0 0 0 0
C'oJ C'oJ C'oJ C'oJ C'oJ C'oJ .,...... .,...... .,...... .,...... .,...... .,......
I I LO LO LO LO
- - - - Q) Q)
c c () () () ()
0 0 0 0 0 0 z z co co co co
0 0 .,...... .,...... .,...... .,......
.. .. .. .. .. ..
.,...... .,...... .,...... .,...... .,...... .,......
0 0 LO LO LO LO .0,.. .... .0,.. .... 0") 0") 0") 0")
= = - - - -
CD r--- 00 00 00 00
I I I I I I co co co co co co
CD r--- 00 0") 0 .,......
I I I I
.,...... .,......
"""" """" """" """"
I I
"""" """"
-= -= Q.) Q.)
+--' +--'
0 0
:::J :::J -= -= c c
0 0
c...::> c...::>
+--' +--'
0 0 = =
0 0
C'oJ C'oJ
0 0
0 0
C'oJ C'oJ .,...... .,......
LO LO
- -
() ()
0 0
co co
.,...... .,...... .. ..
.,...... .,......
LO LO
0") 0")
- -
00 0")
I I co co
C'oJ C'? .,...... .,......
I I
"""" """"
-= Q.)
+--'
0
:::J -= c
0
c...::>
+--'
0 =
0
C'oJ
0
0
C'oJ .,......
LO
-
()
0
co
.,...... ..
.,......
LO
0")
-
0")
I co
.","..".."..
I
""""
-= Q.)
+--'
0
:::J -= c
0
c...::>
+--'
0 =
0
C'oJ
0
0
C'oJ .,......
r---
-
()
0
co
.,...... ..
.,......
C'?
0")
-
0")
I co
LO .,......
I
""""
a)
:::0
tU
+'
Q)
>
0
..c
tU
Q)
...c
+'
c
0
b.O
~
en
Q)
+'
tU
t) :..c c
en
Q)
+'
tU
t) :..c c
The redundant annealing separator is removed by water-washing from the
obtained final annealed steel sheet. In any steel sheets except for the test numbers 4-6
5 and 4-7, the glass film (forsterite film) was not formed when confirmed by X-ray
diffraction method. In the steel sheets of the test numbers 4-6 and 4-7, the forsterite
film formed on the surface was removed by grinding or pickling the surface of the final
annealed steel sheet after the final annealing. Thereafter, in any steel sheets, the glass
85
film (forsterite film) was not formed when confirmed by X-ray diffraction method.
[0231]
The steel sheets after removing the redundant annealing separator by
water-washing (the steel sheets after removing the glass film in the test numbers 4-6 and
5 4-7) were subjected to the pickling treatment under conditions shown in the following
Table 8.
[0232]
[Table 8]
Ul
00 r.J..J. .. Ul 1...-."..' 0 n 0 n ~ ~ 8' ~
~ 0 '""! rJJ
1--' ~ 0"' N
"'d (D u:;
§. ~ "'d ~ 1-"' ...... ,.0
~ ::s (D
~ 0.. (D
"""'" """'" 0 ~
~(D 0
~ """'" rJJ ::s 0"' rJJ 0.. (D 0
PRODUCTION CONDITIONS
OXIDIZING PROCESS
WASHING PICKLING
No. STEEL TYPE WASHING CONCENTRATION
1-"'
rJJ """'" """'" ~ """'"
0"' (D ......
~ (D 0 (D 1-"' ::s
rJJ
~
0"
:< 0"' (D g. (D .0..."..' """'" n rJJ (D 0"'
~ "("D"'" ::::P s
(D ~ ::s
rJJ '""! ...... ...... ::s
g. 0 1-"'
::s "< (D I
METHOD OF
SULFURIC ACID
mass%
4-1 B-1 Water Washing 10
4-2 B-2 Water Washing 10
4-3 B-3 Water Washing 10
4-4 B-4 Water Washing 10
......
0 ::s ......
::s >< n 1-"'
rJJ ......
~1-" ' 0........ ~ ~ N 0.. ...... (D
0..
...... ::s 0
4-5 B-5 Water Washing 10
4-6 B-6 Water Washing 10
4-7 B-7 Water Washing 10
(fq
~ ::s
n "'d ~ '""! §. 0 0 ~ n """'" (D ::s ......
~ ::s rJJ
(fq ~rJJ s ~ g. "'d 0"' (D 0"' 0
rJJ rJJ 0
(D 0 rJJ 1-"' "'d
n ~ 0"' 0 "..".".'".. ~
~...... 0::s (D
::s §
(fq ~
~ ~ 0.. rJJ n (D ...... 0" 0
4-8 B-8 Water Washing 1
4-9 B-8 Water Washing 5
4-10 B-8 Water Washing 5
4-11 B-8 Water Washing 5
4-12 B-8 Water Washing 5
4-13 B-9 Water Washing Not Conducted
4-14 B-9 Water Washing Not Conducted
4-15 B-9 Water Washing Not Conducted
1-"' era. ~ 01- "' """'" (D ...... 0.. 0..
~
~ 1-"'
HEAT TREATMENT
TEMPERATURE ATMOSPHERE
NITROGEN HYDROGEN
CONCENTRA Tl ON CONCENTRATION
oc volume% volume%
80 100 0
85 100 0
80 100 0
85 100 0
80 100 0
80 100 0
80 100 0
70 100 0
25 100 0
70 95 0
70 100 0
70 100 0
Not Conducted 25 75
Not Conducted 25 75
Not Conducted 97 3
OXYGEN DEW POINT
CONCENTRATION
volume% oc
0 30
0 30
0 30
0 30
0 30
0 30
0 30
0 30
0 30
5 30
0 0
0 30
0 -2
0 0
0 0
TEMPERATURE
oc
800
800
800
800
800
800
800
700
700
800
800
950
800
800
800
TIME
seconds
20
20
20
20
20
20
20
10
10
10
10
10
10
10
10
00
087
was 4.5 g/m2 was formed on the surface of the steel sheets. The laser beam was
irradiated on the test piece in order to refine the magnetic domain.
[0234]
The base steel sheets of the grain oriented electrical steel sheets were chemically
5 analyzed on the basis of the above method. The chemical compositions are shown in
Table 9. In regard to Table 6 and Table 9, the element which is expressed in blanc or"-"
in the tables indicates the element in which the purposeful control is not conducted for
the amount thereof during production.
10
[0235]
[Table 9]
1~
~
~
~ ~ ...... 0
0 N
::s u:;
v 2J
No. STEEL TYPE
4-1 B-1
4-2 B-2
4-3 B-3
4-4 B-4
4-5 B-5
4-6 B-6
4-7 B-7
4-8 B-8
4-9 B-8
4-10 B-8
4-11 B-8
4-12 B-8
4-13 B-9
4-14 B-9
4-15 B-9
PRODUCTION RESULTS
CHEMICAL COMPOSITION OF GRAIN ORIENTED ELECTRICAL STEEL SHEET (UNIT: mass%. BALANCE CONSISTING OF Fe AND IMPURITIES)
c Si Mn s Se s soLA I N Bi
+Se
~0.002 3.31 0.080 ~0.005 ~0.001 ~0.005 ~0.005 ~0.005 0.0001
~0.002 3.31 0.080 ~0.005 ~0.001 ~0.005 ~0.005 ~0.005 0.0001
~0.002 3.22 0.075 ~0.005 ~0.001 ~0.005 ~0.005 ~0.005 -
~0.002 3.32 0.080 ~0.005 ~0.001 ~0.005 ~0.005 ~0.005 -
~0.002 3.31 0.080 ~0.005 ~0.001 ~0.005 ~0.005 ~0.005 0.0001
~0.002 3.51 0.077 ~0.005 ~0.001 ~0.005 ~0.005 ~0.005 -
~0.002 3.22 0.080 ~0.005 ~0.001 ~0.005 ~0.005 ~0.005 0.0001
~0.002 3.31 0.082 ~0.005 ~0.001 ~0.005 ~0.005 ~0.005 -
~0.002 3.31 0.082 ~0.005 ~0.001 ~0.005 ~0.005 ~0.005 -
~0.002 3.31 0.082 ~0.005 ~0.001 ~0.005 ~0.005 ~0.005 -
~0.002 3.31 0.082 ~0.005 ~0.001 ~0.005 ~0.005 ~0.005 -
~0.002 3.31 0.082 ~0.005 ~0.001 ~0.005 ~0.005 ~0.005 -
~0.002 3.31 0.082 ~0.005 ~0.001 ~0.005 ~0.005 ~0.005 0.0001
~0.002 3.31 0.082 ~0.005 ~0.001 ~0.005 ~0.005 ~0.005 0.0001
~0.002 3.31 0.082 ~0.005 ~0.001 ~0.005 ~0.005 ~0.005 0.0001
Te Pb Sb
- - 0.021
- - -
0.0001 - -
- 0.0015 0.043
0.0001 - -
0.0001 00011 -
- 0.0015 -
- - -
- - -
- - -
- - -
- - -
- - -
- - -
- - -
Sn Cr
- 0.04
0.031 0.12
- 0.13
0.040 0.25
- 0.03
- 0.05
- 0.03
- 0.04
- 0.04
- 0.04
- 0.04
- 0.04
- 0.04
- 0.04
- 0.04
Cu
-
-
0.032
0.046
-
-
-
-
-
-
-
-
-
-
-
00
00
89
The magnetic characteristics, the GDS analysis, the coating adhesion, and the
like were evaluated. The evaluation methods were the same as those in the Example 2.
Herein, when the average of B8 was 1.90 T or more, when the average of W17 /50 was
0.700 W/kg or less, and when the standard deviation ofW17/50 was 0.021 W/kg or less,
5 it was judged to as acceptable.
[0237]
The obtained results are summarized in the following Table 10.
[0238]
[Table 10]
> 0 rJJ N n u:;
I-"' (D :::s e; PRODUCTION RESULTS
I-"'
"< AFTER OXIDIZING PROCESS
rJJ
0"'
0
~ ::s
STEEL
CONDITION CONDITION CONDITION
No. (!) (II) (Ill)
...... TYPE PRESENCE RATIO RATIO
::s OF OF OF
"0"""'"' PLATEAU Cr EMISSION Si EMISSION
(D
~
0"
REGION INTENSITY INTENSITY
4-1 B-1 Presence 0.021 0.098
I-"'
(D
rJJ 4-2 B-2 Presence 0.027 0.130
0\ 4-3 B-3 Presence 0.019 0.117
"0"" '" 4-4 B-4 Presence 0.028 0.076
1--'
~0 4-5 B-5 Presence 0.019 0.087
r.J..J. .. 4-6 B-6 Presence 0.017 0.097 ::s n
(D
4-7 B-7 Presence 0.019 0.093
g. 4-8 B-8 Presence 0.008 0.050
(D
n 4-9 B-8 Presence 0.009 0.052
0"'
(D 4-10 B-8 Presence 0.047 0.217 s...... 4-11 B-8 Presence 0.046 0.242
n
~
I-"' 4-12 B-8 Presence 0.040 0.160
n
0 4-13 B-9 Absence 0.008 0.781
.§ 4-14 B-9 Absence 0.008 0.873
0
rJJ ...... 4-15 B-9 Absence 0.008 0.312
"..".".'"..
0 ::s
rJJ
0... ..,
"0"""'"'
(D
EVALUATION RESULTS
AFTER INSULATION COATING FORMING PROCESS MAGNETIC CHARACTERISTICS
(Fe0_5-Feo.os) RATIO AVERAGE Bs W1715o
/Feo.s OF THICKNESS
Cr EMISSION OF INSULATION
AVERAGE AVERAGE
INTENSITY COATING
Jim T W/kg
0.67 0.19 2.0 1.986 0.617
0.61 0.23 2.0 1.986 0.621
0.55 0.18 2.0 1.987 0.620
0.63 0.22 2.0 1.965 0.647
0.56 0.19 2.0 1.983 0.628
0.55 0.21 2.0 1.981 0.629
0.61 0.24 2.0 1.984 0.625
0.38 0.07 2.0 1.921 0.737
0.37 0.06 2.0 1.923 0.738
0.36 0.26 2.0 1.924 0.735
0.36 0.27 2.0 1.921 0.738
0.48 0.29 2.0 1.922 0.739
0.36 0.04 2.0 1.961 0.736
0.36 0.05 2.0 1.969 0.734
0.34 0.04 2.0 1.967 0.738
ADHESION
Wn/50 ¢20
STANDARD BENDING
DEVIATION
W/kg
0.021 A
0.018 A
0.017 A
0.014 A
0.018 A
0.016 A
0.021 A
0.024 B
0.022 B
0.039 B
0.041 B
0.028 c
0.047 c
0.051 c
0.043 c
¢10
BENDING
A
A
A
A
A
A
A
B
B
B
B
c
c
c
c
REMARKS
INVENTIVE EXAMPLE
INVENTIVE EXAMPLE
INVENTIVE EXAMPLE
INVENTIVE EXAMPLE
INVENTIVE EXAMPLE
INVENTIVE EXAMPLE
INVENTIVE EXAMPLE
COMPARATIVE EXAMPLE
COMPARATIVE EXAMPLE
COMPARATIVE EXAMPLE
COMPARATIVE EXAMPLE
COMPARATIVE EXAMPLE
COMPARATIVE EXAMPLE
COMPARATIVE EXAMPLE
COMPARATIVE EXAMPLE
\0
0
91
base steel sheets were satisfied and the production conditions were satisfied in the test
numbers 4-1 to 4-7, both magnetic characteristics and adhesion of the tension-insulation
coating were excellent. On the other hand, since the production conditions were not
favorable in the test numbers 4-8 and 4-15, the magnetic characteristics and the adhesion
5 of the tension-insulation coating were inferior.
Industrial Applicability
[0240]
According to the above aspects of the present invention, it is possible to provide
10 the grain oriented electrical steel sheet in which the adhesion of the tension-insulation
coating is excellent and the effect in improving the iron loss is obtained stably (the
fluctuation of the iron loss is small) even without the glass film (forsterite film). In
addition, it is possible to provide the method for forming the above insulation coating
and for producing the above grain oriented electrical steel sheet. Accordingly, the
15 present invention has significant industrial applicability.
Reference Signs List
[0241]
10 Grain oriented electrical steel sheet
20 11 Base steel sheet
13 Tension-insulation coating
15 Oxide layer

WE CLAIMS

1. A grain oriented electrical steel sheet without a forsterite film characterized in
that
the grain oriented electrical steel sheet comprises:
a base steel sheet;
an oxide layer arranged in contact with the base steel sheet; and
a tension-insulation coating arranged in contact with the oxide layer,
wherein the base steel sheet includes, as a chemical composition, by mass%,
2.5 to 4.0% of Si,
0.05 to 1.0% of Mn,
0.02 to 0.50% of Cr,
0 to 0.01% of C,
0 to 0.005% of S+Se,
0 to 0.01% of sol.Al,
0 to 0.005% of N,
0 to 0.03% of Bi,
0 to 0.03% of Te,
0 to 0.03% of Pb,
0 to 0.50% of Sb,
0 to 0.50% of Sn,
0 to 1.0% of Cu, and
a balance consisting of Fe and impurities,
the tension-insulation coating is a phosphate-silica mixed tension-insulation
25 coating with an average thickness of 1 to 3 ~m,
93
when a glow discharge spectroscopy is conducted in a region from a surface of
the tension-insulation coating to an inside of the base steel sheet, when a sputtering time
at which a Fe emission intensity becomes 0.5 times as compared with a saturation value
thereof on a depth profile is referred to as Feo.s in unit of seconds, and when a sputtering
5 time at which a Fe emission intensity becomes 0.05 times as compared with the
saturation value on the depth profile is referred to as Feo.os in unit of seconds, the Feo.s
and the Feo.os satisfy (Feo.s - Feo.os) I Feo.s 2:: 0.35,
when a sputtering time at which a Fe emission intensity becomes the saturation
value on the depth profile is referred to as Fesat in unit of seconds, and when a sputtering
10 time at which a Cr emission intensity becomes a maximal value on the depth profile is
referred to as Crmax in unit of seconds, a maximal point of a Cr emission intensity at
which a Cr emission intensity at the Crmax becomes 0.08 to 0.25 times as compared with
a Fe emission intensity at the Crmax is included between the Feo.os and the Fesat on the
depth profile, and
15
20
a magnetic flux density B8 in a rolling direction of the grain oriented electrical
steel sheet is 1. 90 T or more.
2. A forming method for an insulation coating of a grain oriented electrical steel
sheet without a forsterite film characterized in that
the forming method for the insulation coating includes an insulation coating
forming process of forming a tension-insulation coating on a steel substrate,
wherein, in the insulation coating forming process,
a solution for forming a phosphate-silica mixed tension-insulation coating is
applied to an oxide layer of the steel substrate and the solution is baked so as to form the
25 tension-insulation coating with an average thickness of 1 to 3 ~m,
5
10
15
94
the steel substrate includes a base steel sheet and the oxide layer arranged in
contact with the base steel sheet,
the base steel sheet includes, as a chemical composition, by mass%,
2.5 to 4.0% of Si,
0.05 to 1.0% of Mn,
0.02 to 0.50% of Cr,
0 to 0.01% of C,
0 to 0.005% of S+Se,
0 to 0.01% of sol.Al,
0 to 0.005% of N,
0 to 0.03% of Bi,
0 to 0.03% of Te,
0 to 0.03% of Pb,
0 to 0.50% of Sb,
0 to 0.50% of Sn,
0 to 1.0% of Cu, and
a balance consisting of Fe and impurities,
when a glow discharge spectroscopy is conducted in a region from a surface of
the oxide layer to an inside of the base steel sheet, when a sputtering time at which a Fe
20 emission intensity becomes a saturation value thereof on a depth profile is referred to as
25
Fesat in unit of seconds, a plateau region of a Fe emission intensity where a Fe emission
intensity stays for Fesat x 0.1 seconds or more in a range of 0.40 to 0.80 times as
compared with the saturation value is included between 0 second and the Fesat on the
depth profile,
when a sputtering time at which a Cr emission intensity becomes a maximal
5
10
95
value on the depth profile is referred to as Crmax in unit of seconds, a maximal point of a
Cr emission intensity at which a Cr emission intensity at the Crmax becomes 0.01 to 0.03
times as compared with a Fe emission intensity at the Crmax is included between the
plateau region and the Fesat on the depth profile, and
when a sputtering time at which a Si emission intensity becomes a maximal
value on the depth profile is referred to as Simax in unit of seconds, a maximal point of a
Si emission intensity at which a Si emission intensity at the Simax becomes 0.06 to 0.15
times as compared with a Fe emission intensity at the Simax is included between the Crmax
and the Fesat on the depth profile.
3. A producing method for a grain oriented electrical steel sheet without a forsterite
film characterized in that
the producing method includes
a hot rolling process of heating and thereafter hot-rolling a steel piece to obtain a
15 hot rolled steel sheet,
a hot band annealing process of optionally annealing the hot rolled steel sheet to
obtain a hot band annealed steel sheet,
a cold rolling process of cold-rolling the hot rolled steel sheet or the hot band
annealed steel sheet by cold-rolling once or by cold-rolling plural times with an
20 intermediate annealing to obtain a cold rolled steel sheet,
a decarburization annealing process of decarburization -annealing the cold rolled
steel sheet to obtain a decarburization annealed steel sheet,
a final annealing process of applying an annealing separator to the
decarburization annealed steel sheet and thereafter final-annealing the decarburization
25 annealed steel sheet to obtain a final annealed steel sheet,
96
an oxidizing process of conducting a washing treatment, a pickling treatment,
and a heat treatment in turn for the final annealed steel sheet to obtain an oxidized steel
sheet, and
an insulation coating forming process of applying a solution for forming a
5 phosphate-silica mixed tension-insulation coating to a surface of the oxidized steel sheet
and of baking the solution so as to form the tension-insulation coating with an average
thickness of 1 to 3 ~m,
10
15
20
25
wherein, in the hot rolling process,
the steel piece includes, as a chemical composition, by mass%,
2.5 to 4.0% of Si,
0.05 to 1.0% of Mn,
0.02 to 0.50% of Cr,
0.02 to 0.10% ofC,
0.005 to 0.080% of S+Se,
0.01 to 0.07% of sol.Al,
0.005 to 0.020% of N,
0 to 0.03% of Bi,
0 to 0.03% of Te,
0 to 0.03% of Pb,
0 to 0.50% of Sb,
0 to 0.50% of Sn,
0 to 1.0% of Cu, and
a balance consisting of Fe and impurities, and
wherein, in the oxidizing process,
as the washing treatment, a surface of the final annealed steel sheet is washed,
97
as the pickling treatment, the final annealed steel sheet is pickled using a sulfuric
acid of 2 to 20 mass% at 70 to 90°C, and
as the heat treatment, the final annealed steel sheet is held in a temperature range
of 700 to 900°C for 10 to 60 seconds in a mixed atmosphere of nitrogen and hydrogen
5 where a dew point is 10 to 30°C and a hydrogen concentration is 0 to 4 volume%.
10
15
20
4. The producing method for the grain oriented electrical steel sheet according to
claim 3,
wherein, in the final annealing process,
the annealing separator includes MgO, Ah03, and a bismuth chloride.
5. The producing method for the grain oriented electrical steel sheet according to
claim 3 or 4,
wherein, in the hot rolling process,
the steel piece includes, as the chemical composition, by mass%, at least one
selected from a group consisting of
0.0005 to 0.03% of Bi,
0.0005 to 0.03% of Te, and
0.0005 to 0.03% of Pb.