[0001]The present invention relates to a grain-oriented electrical steel sheet and a
method of producing the same, and particularly, to a grain-oriented electrical steel sheet
that exhibits excellent iron loss characteristics due to surface properties of a silicon steel
10 sheet which is a base steel sheet being controlled and a method of producing the same.
Priority is claimed on Japanese Patent Application No. 2019-5396, filed January
16, 2019, and Japanese Patent Application No. 2019-5398, filed January 16, 2019, the
content of which is incorporated herein by reference.
[Background Art]
15 [0002]
A grain-oriented electrical steel sheet includes a silicon steel sheet as a base steel
sheet and is a soft magnetic material that is mainly used as an iron core material of a
transformer. Grain -oriented electrical steel sheets are required to exhibit excellent
magnetic properties. In particular, it is required that excellent iron loss characteristics
20 be exhibited.
[0003]
The iron loss means an energy loss that occurs when electrical energy and
magnetic energy are mutually converted. A smaller value for the iron loss is more
preferable. Iron loss can be roughly divided into two loss components: hysteresis loss
25 and eddy current loss. In addition, the eddy current loss can be divided into classical
1
eddy current loss and anomalous eddy current loss.
[0004]
For example, increasing the electrical resistance of a silicon steel sheet, reducing
the thickness of a silicon steel sheet, and insulating a silicon steel sheet by the coating
5 have been attempted to reduce the classical eddy current loss. In addition, reducing the
grain size of a silicon steel sheet, reducing the magnetic domain of a silicon steel sheet
and applying tension to a silicon steel sheet have been attempted to reduce the anomalous
eddy current loss. In addition, removing impurities in a silicon steel sheet and
controlling the crystal orientation of the silicon steel sheet have been attempted to reduce
10 the hysteresis loss.
[0005]
In addition, making the surface of a silicon steel sheet smooth has been
attempted to reduce the hysteresis loss. When the surface of a silicon steel sheet has
irregularities, they hinder movement of the domain wall, and magnetization is unlikely to
15 occur. Therefore, reducing the energy loss due to the domain wall motion by reducing
the surface roughness of the silicon steel sheet has been attempted.
[0006]
For example, Patent Document 1 discloses a grain-oriented electrical steel sheet
in which excellent iron loss characteristics are obtained by smoothing the surface of the
20 steel sheet. Patent Document 1 discloses that, when the surface of the steel sheet is
mirror-finished by chemical polishing or electrolytic polishing, the iron loss significantly
decreases.
[0007]
Patent Document 2 discloses a grain-oriented electrical steel sheet in which the
25 surface roughness Ra of the steel sheet is controlled such that it is 0.4 ~m or less.
2
Patent Document 2 discloses that, when the surface roughness Ra is 0.4 ~m or less, a
very low iron loss is obtained.
[0008]
Patent Document 3 discloses a grain-oriented electrical steel sheet in which the
5 surface roughness Ra of the steel sheet in a direction perpendicular to a rolling direction
is controlled such that it is 0.15 to 0.45 ~m. Patent Document 3 discloses that, when the
surface roughness in the direction perpendicular to the rolling direction is larger than
0.45 ~m, an effect of improving the high magnetic field iron loss becomes weak.
10
[0009]
Patent Document 4 and Patent Document 5 disclose non-oriented electrical steel
sheets in which the surface roughness Ra is controlled such that it is 0.2 ~m or less when
the cutoff wavelength J...c is 20 ~m. Patent Document 4 and Patent Document 5 disclose
that, in order to reduce the iron loss, it is necessary to remove undulations on the longer
wavelength side at a cutoff wavelength, evaluate fine irregularities, and reduce the
15 amount of these fine irregularities.
20
[Citation List]
[Patent Document]
[0010]
[Patent Document 1]
Japanese Examined Patent Application, Second Publication No. S52-024499
[Patent Document 2]
Japanese Unexamined Patent Application, First Publication No. H05-311453
[Patent Document 3]
Japanese Unexamined Patent Application, First Publication No. 2018-062682
25 [Patent Document 4]
3
Japanese Unexamined Patent Application, First Publication No. 2016-47942
[Patent Document 5]
Japanese Unexamined Patent Application, First Publication No. 2016-47943
[Summary of the Invention]
5 [Problems to be Solved by the Invention]
[0011]
The inventors conducted studies, and as a result, clarified that, as in the related
art, even if the surface roughness Ra of a silicon steel sheet is controlled such that it is,
for example, 0.40 ~m or less, or the surface roughness Ra is controlled such that it is 0.2
10 ~m or less under conditions of a cutoff wavelength J...c of 20 ~m, the iron loss
characteristics are not always sufficiently and stably improved.
[0012]
Furthermore, in Patent Document 4 and Patent Document 5, in order to improve
iron loss characteristics of the non-oriented electrical steel sheet, the surface properties of
15 the silicon steel sheet are controlled by cold rolling. However, in the grain-oriented
electrical steel sheet, unlike a non-oriented electrical steel sheet, after cold rolling,
decarburization annealing is performed, an annealing separator is applied, final annealing
is performed, and additionally purification annealing is performed at a high temperature
for a long time. Therefore, in the grain-oriented electrical steel sheet, it is difficult to
20 maintain the surface properties controlled by cold rolling until after the final process,
unlike a non-oriented electrical steel sheet. Generally, knowledge about a non-oriented
electrical steel sheets cannot simply be applied to a grain-oriented electrical steel sheet.
[0013]
The inventors consider surface control of grain-oriented electrical steel sheets to
25 be insufficient in the related art, and, with a new perspective, postulate that, in order to
4
optimally improve iron loss characteristics of a grain-oriented electrical steel sheet, it
would be necessary to control surface properties of a silicon steel sheet.
[0014]
That is, an object of the present invention is to provide a grain-oriented electrical
5 steel sheet that exhibits excellent iron loss characteristics due to optimally controlling
surface properties of a silicon steel sheet which is a base steel sheet and a method of
producing the same.
10
[Means for Solving the Problem]
[0015]
The scope of the present invention is as follows.
[0016]
(1) A grain-oriented electrical steel sheet according to an aspect of the present invention
includes a silicon steel sheet as a base steel sheet, and when an average value of
amplitudes in a wavelength range of 20 to 100 ~m among wavelength components
15 obtained by performing Fourier analysis on a measured cross-sectional curve parallel to a
sheet width direction of the silicon steel sheet is set as ave-AMPcwo, ave-AMPcwo is
0.0001 to 0.050 ~m.
(2) In the grain-oriented electrical steel sheet according to (1), ave-AMPcwo may be
0.0001 to 0.025 ~m.
20 (3) In the grain-oriented electrical steel sheet according to (1) or (2), when a maximum
value of amplitudes in a wavelength range of 20 to 100 ~m among wavelength
components obtained by performing Fourier analysis on the measured cross-sectional
curve parallel to the sheet width direction of the silicon steel sheet is set as max-AMPcwo
and a maximum value of amplitudes in a wavelength range of 20 to 100 ~m among
25 wavelength components obtained by performing Fourier analysis on a measured cross-
5
sectional curve parallel to the rolling direction of the silicon steel sheet is set as maxAMPuoo,
max-DIV 100, which is a value obtained by dividing max-AMPc10o by maxAMPuoo,
may be 1.5 to 6.0.
(4) In the grain-oriented electrical steel sheet according to any one of (1) to (3), when an
5 average value of amplitudes in a wavelength range of 20 to 50 ~m among the wavelength
components obtained by performing Fourier analysis is set as ave-AMPcso, ave-AMPcso
may be 0.0001 to 0.035.
(5) In the grain-oriented electrical steel sheet according to (4), when a maximum value of
amplitudes in a wavelength range of 20 to 50 ~m among wavelength components
10 obtained by performing Fourier analysis on the measured cross-sectional curve parallel to
the sheet width direction of the silicon steel sheet is set as max-AMPcso and a maximum
value of amplitudes in a wavelength range of 20 to 50 ~m among wavelength
components obtained by performing Fourier analysis on the measured cross-sectional
curve parallel to the rolling direction of the silicon steel sheet is set as max-AMPLso,
15 max-DIVso, which is a value obtained by dividing max-AMPcso by max-AMPLso, may be
1.5 to 5.0.
(6) In the grain-oriented electrical steel sheet according to (4) or (5), ave-AMPcso may be
0.0001 to 0.020 ~m.
(7) In the grain-oriented electrical steel sheet according to any one of (1) to (6), the
20 silicon steel sheet may contain, as chemical components, by mass%, Si: 0.8% or more
and 7.0% or less, Mn: 0 or more and 1.00% or less, Cr: 0 or more and 0.30% or less, Cu:
0 or more and 0.40% or less, P: 0 or more and 0.50% or less, Sn: 0 or more and 0.30% or
less, Sb: 0 or more and 0.30% or less, Ni: 0 or more and 1.00% or less, B: 0 or more and
0.008% or less, V: 0 or more and 0.15% or less, Nb: 0 or more and 0.2% or less, Mo: 0 or
25 more and 0.10% or less, Ti: 0 or more and 0.015% or less, Bi: 0 or more and 0.010% or
6
less, Al: 0 or more and 0.005% or less, C: 0 or more and 0.005% or less, N: 0 or more
and 0.005% or less, S: 0 or more and 0.005% or less, and Se: 0 or more and 0.005% or
less with the remainder being Fe and impurities.
(8) In the grain-oriented electrical steel sheet according to any one of (1) to (7), the
5 silicon steel sheet may have a texture developed in the { 110 }<001> orientation.
(9) The grain-oriented electrical steel sheet according to any one of (1) to (8) may further
include an intermediate layer arranged in contact with the silicon steel sheet, and the
intermediate layer may be a silicon oxide film.
(1 0) The grain-oriented electrical steel sheet according to (9) may further an insulation
10 coating arranged in contact with the intermediate layer, and the insulation coating may be
a phosphoric acid-based coating.
(11) The grain-oriented electrical steel sheet according to (9) may further include an
insulation coating arranged in contact with the intermediate layer, and the insulation
coating is an aluminum borate-based coating.
15 (12) A method of producing the grain-oriented electrical steel sheet according to any one
of (1) to (11) includes producing a grain-oriented electrical steel sheet using the silicon
steel sheet as a base.
20
[Effects of the Invention]
[0017]
According to the above aspects of the present invention, it is possible to provide
a grain-oriented electrical steel sheet that exhibits excellent iron loss characteristics by
optimally controlling surface properties of a silicon steel sheet which is a base steel sheet
and a method of producing the same.
[Brief Description of Drawings]
25 [0018]
7
Fig. 1 shows a graph illustrating a plot of the amplitude with respect to the
wavelength from Fourier analysis of a measured cross-sectional curve parallel to a sheet
width direction of a silicon steel sheet, regarding a grain-oriented electrical steel sheet
according to one embodiment of the present invention and a conventional grain-oriented
5 electrical steel sheet.
Fig. 2 is a microscopic image showing an example of a magnetic domain
structure of the grain-oriented electrical steel sheet.
Fig. 3 shows a graph illustrating a plot of the amplitude with respect to the
10 wavelength from Fourier analysis of a measured cross-sectional curve parallel to a sheet
width direction and a rolling direction of a silicon steel sheet, regarding the grainoriented
electrical steel sheet according to the same embodiment.
[Embodiment(s) for implementing the Invention]
[0019]
15 Preferable embodiments of the present invention will be described below in
detail. However, the present invention is not limited to only the configuration disclosed
in the present embodiment, and can be variously modified without departing from the
gist of the present invention. In addition, lower limit values and the upper limit values
are included in the numerical value limiting ranges stated below. Numerical values
20 indicated by "more than" or "less than" are not included in these numerical value ranges.
"%"indicating the amount of respective elements means "mass%".
[0020]
[First embodiment]
In the present embodiment, unlike the related art, a surface state of a silicon steel
25 sheet which is a base steel sheet of a grain-oriented electrical steel sheet is precisely and
8
optimally controlled. Specifically, the surface properties of the silicon steel sheet are
controlled in a sheet width direction (C direction) in a wavelength range of 20 to 100 ~m.
[0021]
For example, inside a transformer, the grain-oriented electrical steel sheet is
5 magnetized with an alternating current. In this manner, when electrical energy and
magnetic energy are mutually converted, in the grain-oriented electrical steel sheet, the
magnetization direction is reversed mainly in a rolling direction (L direction) according
to the AC cycle.
10
[0022]
When the magnetization direction is reversed in the rolling direction, in the
grain-oriented electrical steel sheet, the domain wall repeatedly moves mainly in the
sheet width direction according to the AC cycle. Therefore, the inventors thought that,
firstly, it is preferable to control a factor that inhibits domain wall motion in the sheet
width direction.
15 [0023]
In addition, when the domain wall repeatedly moves in the sheet width direction
according to the AC cycle, in consideration of the size of the magnetic domain of the
grain-oriented electrical steel sheet, the moving distance of the domain wall is estimated
to be about 20 to 100 ~m. Fig. 2 shows a microscopic image of magnetic domain
20 structure examples of a grain-oriented electrical steel sheet. As shown in Fig. 2, the
grain-oriented electrical steel sheet basically has a stripe-shaped magnetic domain
structure parallel to the rolling direction (L direction). In the grain-oriented electrical
steel sheet, the width of the magnetic domain in the sheet width direction (C direction) is
generally about 20 to 100 ~m. Therefore, the inventors thought that, secondly, it is
25 preferable to control a factor that inhibits domain wall motion in an area of 20 to 100 ~m.
9
[0024]
The grain -oriented electrical steel sheet according to the present embodiment is
obtained based on the above findings. In the present embodiment, among wavelength
components obtained by performing Fourier analysis on a measured cross-sectional curve
5 parallel to the sheet width direction of the silicon steel sheet (base steel sheet), an
amplitude in a wavelength range of 20 to 100 ~m is controlled.
[0025]
Specifically, when the average value of amplitudes in a wavelength range of 20
to 100 ~m among the wavelength components obtained by performing Fourier analysis is
10 set as ave-AMPcwo, ave-AMPcwo is controlled such that it is 0.050 ~m or less. When
ave-AMPcwo is 0.050 ~m or less, the domain wall motion is not hindered by surface
unevenness, and the domain wall can move suitably in the sheet width direction. As a
result, the iron loss can be suitably reduced. In order to further facilitate the domain
wall motion, ave-AMPcwo is preferably 0.040 ~m or less, more preferably 0.030 ~m or
15 less, still more preferably 0.025 ~m or less, and most preferably 0.020 ~m or less.
[0026]
Since a smaller value of ave-AMPcwo is more preferable, the lower limit of aveAMPcwo
is not particularly limited. However, since it is not industrially easy to control
ave-AMPcwo such that it is less than 0.0001 ~m, ave-AMPcwo may be 0.0001 ~m or
20 more.
[0027]
In addition, it is preferable to control the value of ave-AMPcwo and then control
an amplitude in a wavelength range of 20 to 50 ~m. Since ave-AMPcwo is an average
value of amplitudes in a wavelength range of 20 to 100 ~m, this value tends to be easily
25 influenced by an amplitude with a large wavelength in a range of 20 to 100 ~m.
10
5
Therefore, in addition to the control of ave-AMPc10o, the amplitude in a wavelength
range of 20 to 50 ~m is also controlled, and thus the surface properties of the silicon steel
sheet can be more suitably controlled.
[0028]
Specifically, when the average value of amplitudes in a wavelength range of 20
to 50 ~m among the wavelength components obtained by performing Fourier analysis is
set as ave-AMPcso, ave-AMPcso is controlled such that it is 0.035 ~m or less. When
ave-AMPcso is 0.035 ~m or less, since the domain wall can more easily move in the sheet
width direction, the iron loss can be suitably reduced. Ave-AMPcso is preferably 0.030
10 ~m or less, more preferably 0.025 ~m or less, still more preferably 0.020 ~m or less, and
most preferably 0.015 ~m or less.
[0029]
Since a smaller value of ave-AMPcso is more preferable, the lower limit of aveAMPcso
is not particularly limited. However, since it is not industrially easy to control
15 ave-AMPcso such that it is less than 0.0001 ~m, ave-AMPcso may be 0.0001 ~m or more.
[0030]
Fig. 1 shows a graph obtained when measured cross-sectional curves parallel to
the sheet width direction of the silicon steel sheet (base steel sheet) is subjected to
Fourier analysis and the amplitude is plotted with respect to the wavelength. As shown
20 in Fig. 1, in the silicon steel sheet of the conventional grain-oriented electrical steel sheet,
the amplitude has a small value in a wavelength range of 20 ~m or less, but the amplitude
has a large value in a wavelength range of more than 20 ~m. Specifically, in the silicon
steel sheet of the conventional grain-oriented electrical steel sheet, the amplitude average
value is 0.02 ~min a wavelength range of 1 to 20 ~m, but the amplitude average value is
25 0.25 ~m in a wavelength range of 20 to 100 ~m. That is, even if surface properties are
11
controlled microscopically in an area with a wavelength of 20 ~m or less, it is clearly
understood that surface properties are not controlled in an area with a wavelength of 20
to 100 ~m, which is important for domain wall motion in the grain-oriented electrical
steel sheet. On the other hand, as shown in Fig. 1, in the silicon steel sheet of the grain-
5 oriented electrical steel sheet according to the present embodiment, the amplitude in a
wavelength range of 20 to 100 ~m has a small value. On the other hand, in the silicon
steel sheet of the conventional grain-oriented electrical steel sheet, the amplitude in a
wavelength range of 20 to 100 ~m has a large value.
10
[0031]
ave-AMPcwo and ave-AMPcso may be measured by, for example, the following
method.
[0032]
When there is no coating on the silicon steel sheet, the surface properties of the
silicon steel sheet may be evaluated directly, and when there is a coating on the silicon
15 steel sheet, the surface properties of the silicon steel sheet may be evaluated after the
coating is removed. For example, a grain-oriented electrical steel sheet having a coating
may be immersed in a high-temperature alkaline solution. Specifically, immersion into
a sodium hydroxide aqueous solution containing NaOH: 20 mass%+H20: 80 mass% is
performed at 80°C for 20 minutes and washing with water and drying are then
20 performed, and thus the coating (the intermediate layer and the insulation coating) on the
silicon steel sheet can be removed. Here, the time for immersion in the sodium
hydroxide aqueous solution may be changed according to the thickness of the coating on
the silicon steel sheet.
[0033]
25 Regarding the surface properties of the silicon steel sheet, in a contact type
12
surface roughness measuring instrument, the contact needle tip radius is generally about
micron (~m), and a fine surface shape cannot be detected. Therefore, it is preferable to
use a non-contact type surface roughness measuring instrument. For example, a laser
type surface roughness measuring instrument (VK-9700 commercially available from
5 Keyence Corporation) may be used.
[0034]
First, a measured cross-sectional curve in the sheet width direction of the silicon
steel sheet is obtained using a non-contact type surface roughness measuring instrument.
When this measured cross-sectional curve is obtained, one measurement length is 500
10 ~m or more, and a total measurement length is 5 mm or more. The spatial resolution in
the measurement direction (the sheet width direction of the silicon steel sheet) is 0.2 ~m
or less. The measured cross-sectional curve is subjected to Fourier analysis without
applying a low pass or high pass filter to the measured cross-sectional curve, that is,
without cutting off a specific wavelength component from the measured cross-sectional
15 curve.
[0035]
Among the wavelength components obtained by performing Fourier analysis on
the measured cross-sectional curve, the average value of amplitudes in a wavelength
range of 20 to 100 ~m is obtained. The average value of the amplitudes is set as ave-
20 AMPcwo. Similarly, among the wavelength components obtained by performing
Fourier analysis on the measured cross-sectional curve, the average value of amplitudes
in a wavelength range of 20 to 50 ~m is obtained. The average value of the amplitudes
is set as ave-AMPcso. Here, the above measurement and analysis may be performed at
five or more locations while changing measurement locations, and the average value
25 thereof may be obtained.
13
[0036]
In the present embodiment, ave-AMPcwo is controlled, and as necessary, aveAMPcso
is controlled to improve iron loss characteristics. A method of controlling
these ave-AMPcwo and ave-AMPcso will be described below.
5 [0037]
In addition, in the grain-oriented electrical steel sheet according to the present
embodiment, configurations other than the above surface properties are not particular! y
limited. However, it is preferable that the grain -oriented electrical steel sheet according
to the present embodiment have the following technical features.
10 [0038]
15
In the present embodiment, it is preferable that the silicon steel sheet contain a
basic element as a chemical component, and as necessary, contain selective elements,
with the remainder being Fe and impurities.
[0039]
In the present embodiment, the silicon steel sheet may contain Si as a basic
element (main alloying element).
[0040]
Si: 0.8% or more and 7.0% or less
Si (silicon) is an element that is a chemical component of the silicon steel sheet
20 and is effective to increase the electrical resistance and reduce the iron loss. When the
Si content is larger than 7 .0%, the material may be easily cracked during cold rolling and
may be difficult to roll. On the other hand, when the Si content is less than 0.8%, the
electrical resistance may become small and the iron loss in the product may increase.
Therefore, Si in a range of 0.8% or more and 7.0% or less may be contained. The lower
25 limit of the Si content is preferably 2.0%, more preferably 2.5%, and still more
14
preferably 2.8%. The upper limit of the Si content is preferably 5.0% and more
preferably 3.5%.
[0041]
In the present embodiment, the silicon steel sheet may contain impurities.
5 Here, "impurities" are those that are mixed in from ore or scrap as a raw material when
steel is industrially produced or from a production environment and the like.
[0042]
In addition, in the present embodiment, the silicon steel sheet may contain
selective elements in addition to the above basic element and impurities. For example,
10 in place of some Fe of the above remainder, Mn, Cr, Cu, P, Sn, Sb, Ni, B, V, Nb, Mo, Ti,
Bi, Al, C, N, S, and Se may be contained as selective elements. These selective
elements may be contained according to the purpose. Therefore, it is not necessary to
limit the lower limit value of these selective elements and the lower limit value may be
0%. In addition, if these selective elements are contained as impurities, the above
15 effects are not impaired.
[0043]
Mn: 0 or more and 1.00% or less
Mn (manganese) is, like Si, an element that is effective in increasing the
electrical resistance and reducing the iron loss. In addition, Mn binds with S or Se and
20 functions as an inhibitor. Therefore, Mn may be contained in a range of 1.00% or less.
The lower limit of the Mn content is preferably 0.05%, more preferably 0.08%, and still
more preferably 0.09%. The upper limit of the Mn content is preferably 0.50% and
more preferably 0.20%.
[0044]
25 Cr: 0 or more and 0.30% or less
15
Cr (chromium) is, like Si, an element that is effective in increasing the electrical
resistance and reducing the iron loss. Therefore, Cr may be contained in a range of
0.30% or less. The lower limit of the Cr content is preferably 0.02% and more
preferably 0.05%. The upper limit of the Cr content is preferably 0.20% and more
5 preferably 0.12%.
[0045]
Cu: 0 or more and 0.40% or less
Cu (copper) is also an element that is effective in increasing the electrical
resistance and reducing the iron loss. Therefore, Cu may be contained in a range of
10 0.40% or less. When the Cu content is larger than 0.40%, the iron loss reducing effect
is saturated, and a surface defect such as a "copper scab" during hot rolling may be
caused. The lower limit of the Cu content is preferably 0.05% and more preferably
0.10%. The upper limit of the Cu content is preferably 0.30% and more preferably
0.20%.
15 [0046]
P: 0 or more and 0.50% or less
P (phosphorus) is also an element that is effective in increasing the electrical
resistance and reducing the iron loss. Therefore, P may be contained in a range of
0.50% or less. When the P content is larger than 0.50%, a problem may occur in the
20 rollability of the silicon steel sheet. The lower limit of the P content is preferably
0.005% and more preferably 0.01 %. The upper limit of the P content is preferably
0.20% and more preferably 0.15%.
[0047]
Sn: 0 or more and 0.30% or less
25 Sb: 0 or more and 0.30% or less
16
Sn (tin) and Sb (antimony) are elements that are effective for stabilizing
secondary recrystallization and developing { 110} <00 1 > orientation. Therefore, Sn may
be contained in a range of 0.30% or less and Sb may be contained in a range of 0.30% or
less. When the Sn or Sb content is larger than 0.30%, magnetic properties may be
5 adversely affected.
The lower limit of the Sn content is preferably 0.02% and more preferably
0.05%. The upper limit of the Sn content is preferably 0.15% and more preferably
0.10%.
The lower limit of the Sb content is preferably 0.01% and more preferably
10 0.03%. The upper limit of the Sb content is preferably 0.15% and more preferably
0.10%.
[0048]
Ni: 0 or more and 1.00% or less
Ni (nickel) is also an element that is effective in increasing the electrical
15 resistance and reducing the iron loss. In addition, Ni is an element that is effective in
controlling a hot-band metal structure and improving magnetic properties. Therefore,
Ni may be contained in a range of 1.00% or less. When the Ni content is larger than
1.00%, secondary recrystallization may become unstable. The lower limit of the Ni
content is preferably 0.01% and more preferably 0.02%. The upper limit of the Ni
20 content is preferably 0.20% and more preferably 0.1 0%.
[0049]
B: 0 or more and 0.008% or less
B (boron) is an element that is effective for exhibiting an inhibitory effect as
BN. Therefore, B may be contained in a range of 0.008% or less. When the B content
25 is larger than 0.008%, magnetic properties may be adversely affected. The lower limit
17
of the B content is preferably 0.0005% and more preferably 0.001%. The upper limit of
the B content is preferably 0.005% and more preferably 0.003%.
[0050]
V: 0 or more and 0.15% or less
5 Nb: 0 or more and 0.2% or less
Ti: 0 or more and 0.015% or less
V (vanadium), Nb (niobium), and Ti (titanium) are elements that are effective in
binding with N or C and functioning as an inhibitor. Therefore, V may be contained in
a range of 0.15% or less, Nb may be contained in a range of 0.2% or less, and Ti may be
10 contained in a range of 0.015% or less. When these elements remain in the final
product (electrical steel sheet) and the V content is larger than 0.15%, the Nb content is
larger than 0.2% or the Ti content is larger than 0.015%, magnetic properties may be
deteriorated.
The lower limit of the V content is preferably 0.002% and more preferably
15 0.01 %. The upper limit of the V content is preferably 0.10% and more preferably
0.05%.
20
25
The lower limit of the Nb content is preferably 0.005% and more preferably
0.02%. The upper limit of the Nb content is preferably 0.1% and more preferably
0.08%.
The lower limit of the Ti content is preferably 0.002% and more preferably
0.004%. The upper limit of the Ti content is preferably 0.010% and more preferably
0.008%.
[0051]
Mo: 0 or more and 0.10% or less
Mo (molybdenum) is also an element that is effective in increasing the electrical
18
resistance and reducing the iron loss. Therefore, Mo may be contained in a range of
0.10% or less. When the Mo content is larger than 0.1 0%, a problem may occur in the
rollability of the steel sheet. The lower limit of the Mo content is preferably 0.005%
and more preferably 0.01 %. The upper limit of the Mo content is preferably 0.08% and
5 more preferably 0.05%.
[0052]
Bi: 0 or more and 0.010% or less
Bi (bismuth) is an element that is effective for stabilizing precipitates such as
sulfide and improving a function as an inhibitor. Therefore, Bi may be contained in a
10 range of 0.010% or less. When the Bi content is larger than 0.010%, magnetic
properties may be adversely affected. The lower limit of the Bi content is preferably
0.001% and more preferably 0.002%. The upper limit of the Bi content is preferably
0.008% and more preferably 0.006%.
[0053]
15 Al: 0 or more and 0.005% or less
Al (aluminum) is an element that is effective in binding with Nand exhibiting
an inhibitory effect. Therefore, before final annealing, for example, Al may be
contained in a range of 0.01 to 0.065% at the slab stage. However, if Al remains as
impurities in the final product (electrical steel sheet) and the Al content is larger than
20 0.005%, magnetic properties may be adversely affected. Therefore, the Al content of
the final product is preferably 0.005% or less. The upper limit of the Al content of the
final product is preferably 0.004% and more preferably 0.003%. Here, the Al content of
the final product corresponds to impurities, the lower limit is not particularly limited, and
a smaller content is more preferable. However, since it is not industrially easy to
25 control the Al content of the final product such that it is 0%, the lower limit of the Al
19
content of the final product may be 0.0005%. Here, the Al content indicates the amount
of acid-soluble Al.
[0054]
C: 0 or more and 0.005% or less,
5 N: 0 or more and 0.005% or less,
C (carbon) is an element that is effective in adjusting primary recrystallization
texture and improving magnetic properties. In addition, N (nitrogen) is an element that
is effective in binding to Al, B, or the like and exhibiting an inhibitory effect.
Therefore, before decarburization annealing, C may be contained in a range of 0.02 to
10 0.1 0%, for example, at the slab stage. In addition, before final annealing, N may be
contained in a range of 0.01 to 0.05%, for example, in the stage after nitriding annealing.
However, when these elements remain as impurities in the final product, and each of the
C and N contents is larger than 0.005%, magnetic properties may be adversely affected.
Therefore, the CorN content in the final product is preferably 0.005% or less. The C
15 or N content in the final product is more preferably 0.004% or less and still more
preferably 0.003% or less. In addition, total amounts of C and N in the final product is
preferably 0.005% or less. Here, C and N in the final product are impurities, and the
content thereof is not particular! y limited, and a smaller content is more preferable.
However, it is not industrially easy to control the CorN content in the final product such
20 that it is 0%, the CorN content in the final product may be 0.0005% or more.
[0055]
S: 0 or more and 0.005% or less,
Se: 0 or more and 0.005% or less
S (sulfur) and Se (selenium) are elements that are effective in bonding to Mn or
25 the like and exhibiting an inhibitory effect. Therefore, before final annealing, S and Se
20
each may be contained in a range of 0.005 to 0.050%, for example, at the slab stage.
However, when these elements remain as impurities in the final product and each of the S
and Se contents is larger than 0.005%, magnetic properties may be adversely affected.
Therefore, the S or Se content in the final product is preferably 0.005% or less. The S
5 or Se content in the final product is preferably 0.004% or less and more preferably
0.003% or less. In addition, total contents of Sand Se in the final product is preferably
0.005% or less. Here, Sand Se in the final product are impurities and the content
thereof is not particularly limited, and a smaller content is more preferable. However, it
is not industrially easy to control the S or Se content in the final product such that it is
10 0%, and the S or Se content in the final product may be 0.0005% or more.
[0056]
In the present embodiment, the silicon steel sheet may contain, as selective
elements, by mass%, at least one selected from the group consisting of Mn: 0.05% or
more and 1.00% or less, Cr: 0.02% or more and 0.30% or less, Cu: 0.05% or more and
15 0.40% or less, P: 0.005% or more and 0.50% or less, Sn: 0.02% or more and 0.30% or
less, Sb: 0.01% or more and 0.30% or less, Ni: 0.01% or more and 1.00% or less, B:
0.0005% or more and 0.008% or less, V: 0.002% or more and 0.15% or less, Nb: 0.005%
or more and 0.2% or less, Mo: 0.005% or more and 0.10% or less, Ti: 0.002% or more
and 0.015% or less, and Bi: 0.001% or more and 0.010% or less.
20 [0057]
The chemical components of the silicon steel sheet described above may be
measured by a general analysis method. For example, a steel component may be
measured using inductively coupled plasma-atomic emission spectrometry (ICP-AES).
Here, C and S may be measured using a combustion-infrared absorption method, N may
25 be measured using an inert gas melting-thermal conductivity method, and 0 may be
21
measured using an inert gas melting-non-dispersive infrared absorption method.
[0058]
In addition, it is preferable that the silicon steel sheet of the grain-oriented
electrical steel sheet according to the present embodiment have a texture developed in
5 { 110}<001> orientation. The { 110}<001> orientation means a crystal orientation
(Goss-orientation) in which the { 110} planes are aligned parallel to the steel sheet
surface and the <100> axes are aligned in the rolling direction. When the silicon steel
sheet is controlled in the Goss-orientation, magnetic properties are preferably improved.
10
[0059]
The texture of the silicon steel sheet described above may be measured by a
general analysis method. For example, it may be measured by an X-ray diffraction
(Laue method). The Laue method is a method of vertically irradiating an X-ray beam to
the steel sheet and analyzing a transmitted or reflected diffraction spots. When the
diffraction spots are analyzed, it is possible to identify crystal orientation of the location
15 to which an X-ray beam is irradiating. If diffraction spots are analyzed at a plurality of
locations while changing the irradiating position, it is possible to measure a crystal
orientation distribution at each irradiating position. The Laue method is a method
suitable for measuring the crystal orientation of a metal structure having coarse crystal
grmns.
20 [0060]
25
In addition, the grain -oriented electrical steel sheet according to the present
embodiment may have an intermediate layer arranged in contact with the silicon steel
sheet or may have an insulation coating arranged in contact with the intermediate layer.
[0061]
The intermediate layer is a silicon oxide film, and contains silicon oxide as a
22
main component, and has a film thickness of 2 nm or more and 500 nm or less. The
intermediate layer continuously extends along the surface of the silicon steel sheet.
When the intermediate layer is formed between the silicon steel sheet and the insulation
coating, the adhesion between the silicon steel sheet and the insulation coating is
5 improved, and stress can be applied to the silicon steel sheet. In the present
embodiment, the intermediate layer is not a forsterite coating but is preferably an
intermediate layer( silicon oxide film) mainly containing silicon oxide.
[0062]
The intermediate layer is formed by heating a silicon steel sheet in which
10 formation of a forsterite coating is restricted during final annealing or a forsterite coating
is removed after final annealing in an atmospheric gas that is adjusted to a predetermined
oxidation degree (PH20/PH2). In the present embodiment, the intermediate layer is
preferably an externally oxidized layer formed by external oxidation.
15
[0063]
Here, external oxidation is oxidation that occurs in a low-oxidation degree
atmospheric gas, and means oxidation in the form in which an alloying element (Si) in a
steel sheet diffuses to the surface of the steel sheet and an oxide is then formed in a film
form on the surface of the steel sheet. On the other hand, internal oxidation is oxidation
that occurs in a relatively high-oxidation degree atmospheric gas, and means oxidation in
20 the form in which an alloying element in a steel sheet hardly diffuses to the surface,
oxygen in the atmosphere diffuses into the steel sheet, and then disperses in an island
form inside the steel sheet and an oxide is formed.
[0064]
The intermediate layer contains silica (silicon oxide) as a main component.
25 The intermediate layer may contain an oxide of alloying elements contained in the silicon
23
steel sheet in addition to silicon oxide. That is, it may contain any oxide of Fe, Mn, Cr,
Cu, Sn, Sb, Ni, V, Nb, Mo, Ti, Bi, and Al or a composite oxide thereof. In addition, it
may contain metal grains such as Fe. In addition, impurities may be contained as long
as the effects are not impaired.
5 [0065]
The average thickness of the intermediate layer is preferably 2 nm or more and
500 nm or less. When the average thickness is less than 2 nm or larger than 500 nm,
this is not preferable because the adhesion between the silicon steel sheet and the
insulation coating decreases, and sufficient stress cannot be applied to the silicon steel
10 sheet, and the iron loss increases. The lower limit of the average film thickness of the
intermediate layer is preferably 5 nm. The upper limit of the average film thickness of
the intermediate layer is preferably 300 nm, more preferably 100 nm, and still more
preferably 50 nm.
15
20
[0066]
The crystal structure of the intermediate layer is not particular! y limited.
However, the matrix phase of the intermediate layer is preferably amorphous. When the
matrix phase of the intermediate layer is amorphous, the adhesion between the silicon
steel sheet and the insulation coating can be preferably improved.
[0067]
In addition, the insulation coating arranged in contact with the intermediate layer
is preferably a phosphoric acid-based coating or an aluminum borate-based coating.
[0068]
When the insulation coating is a phosphoric acid-based coating, preferably, the
phosphoric acid-based coating contains a phosphorus silicon composite oxide (composite
25 oxide containing phosphorous and silicon) and has a film thickness of 0.1 ~m or more
24
and 10 ~m or less. The phosphoric acid-based coating continuously extends along the
surface of the intermediate layer. When the phosphoric acid-based coating arranged in
contact with the intermediate layer is formed, it is possible to further apply tension to the
silicon steel sheet and suitably reduce the iron loss.
5 [0069]
The phosphoric acid-based coating may contain an oxide of alloying elements
contained in the silicon steel sheet in addition to the phosphorus silicon composite oxide.
That is, it may contain any oxide of Fe, Mn, Cr, Cu, Sn, Sb, Ni, V, Nb, Mo, Ti, Bi, and Al
or a composite oxide thereof. In addition, it may contain metal grains such as Fe. In
10 addition, impurities may be contained as long as the effects are not impaired.
[0070]
The average thickness of the phosphoric acid-based coating is preferably 0.1 ~m
or more and 10 ~m or less. The upper limit of the average thickness of the phosphoric
acid-based coating is preferably 5 ~m and more preferably 3 ~m. The lower limit of the
15 average thickness of the phosphoric acid-based coating is preferably 0.5 ~m and more
preferably 1 ~m.
[0071]
The crystal structure of the phosphoric acid-based coating is not particularly
limited. However, the matrix phase of the phosphoric acid-based coating is preferably
20 amorphous. When the matrix phase of the phosphoric acid-based coating is amorphous,
the adhesion between the silicon steel sheet and the phosphoric acid-based coating can be
suitably improved.
[0072]
In addition, when the insulation coating is an aluminum borate-based coating,
25 preferably, the aluminum borate-based coating contains aluminum/boron oxide and has a
25
film thickness of larger than 0.5 ~m and 8 ~m or less. The aluminum borate-based
coating continuously extends along the surface of the intermediate layer. When the
aluminum borate-based coating arranged in contact with the intermediate layer is formed,
it is possible to further apply tension to the silicon steel sheet and suitably reduce the iron
5 loss. For example, the aluminum borate-based coating can apply tension 1.5 to 2 times
that of the phosphoric acid-based coating to the silicon steel sheet.
[0073]
The aluminum borate-based coating may contain crystalline AhsB4033, Al4B209,
aluminum oxide, or boron oxide in addition to aluminum/boron oxide. In addition, it
10 may contain metal grains such as Fe or an oxide. In addition, impurities may be
contained as long as the effects are not impaired.
[0074]
The average thickness of the aluminum borate-based coating is preferably more
than 0.5 ~m and 8 ~m or less. The upper limit of the average thickness of the aluminum
15 borate-based coating is preferably 6 ~m and more preferably 4 ~m. The lower limit of
the average thickness of the aluminum borate-based coating is preferably 1 ~m and more
preferably 2 ~m.
[0075]
The crystal structure of the aluminum borate-based coating is not particularly
20 limited. However, the matrix phase of the aluminum borate-based coating is preferably
amorphous. When the matrix phase of the aluminum borate-based coating is
amorphous, the adhesion between the silicon steel sheet and the aluminum borate-based
coating can be suitably improved.
[0076]
25 The coating structure of the above grain-oriented electrical steel sheet may be
26
observed by, for example, the following method.
[0077]
A test piece is cut out from the grain-oriented electrical steel sheet, and the layer
structure of the test piece is observed under a scanning electron microscope (SEM) or a
5 transmission electron microscope (TEM). For example, a layer with a thickness of 300
nm or more may be observed under an SEM and a layer with a thickness of less than 300
nm may be observed under a TEM.
[0078]
Specifically, first, a test piece is cut out so that the cutting direction is parallel to
10 the sheet thickness direction (specifically, a test piece is cut out so that the cut surface is
parallel to the sheet thickness direction and perpendicular to the rolling direction), and
the cross-sectional structure of the cut surface is observed under an SEM at a
magnification at which each layer is within an observation field of view. For example,
when observed in a backscattered electron composition image (COMPO image), it is
15 possible to infer the number of layers constituting the cross-sectional structure. For
example, in the COMPO image, the silicon steel sheet can be identified as a light color,
the intermediate layer can be identified as a dark color, and the insulation coating (the
aluminum borate-based coating or the phosphoric acid-based coating) can be identified as
a neutral color.
20 [0079]
In order to specify each layer in the cross-sectional structure, using energy
dispersive X-ray spectroscopy (SEM-EDS), line analysis is performed in the sheet
thickness direction, and quantitative analysis of chemical components of each layer is
performed. The elements to be quantitatively analyzed are 6 elements: Fe, P, Si, 0, Mg,
25 and Al. The device to be used is not particular! y limited, but in the present embodiment,
27
5
for example, SEM (NB5000 commercially available from Hitachi High-Technologies
Corporation), EDS (XFlash(r) 6130 commercially available from Bruker AXS), and EDS
analysis software (ESPRIT1.9 commercially available from Bruker AXS) may be used.
[0080]
Based on the observation results of COMPO images and quantitative analysis
results of SEM -EDS described above, if there is a layered area present at the deepest
position in the sheet thickness direction, which is an area in which the Fe content is 80
atom% or more and the 0 content is less than 30 atom% excluding measurement noise
and the line segment (thickness) on the scan line for line analysis corresponding to this
10 area is 300 nm or more, this area is determined as a silicon steel sheet, and an area
excluding the silicon steel sheet is determined as an intermediate layer and an insulation
coating (an aluminum borate-based coating or a phosphoric acid-based coating).
[0081]
Regarding the area excluding the silicon steel sheet specified above, based on
15 the observation results of COMPO images and quantitative analysis results of SEM-EDS,
if there is an area in which the Fe content is less than 80 atom%, the P content is 5
atom% or more, and the 0 content is 30 atom% or more excluding measurement noise
and the line segment (thickness) on the scan line for line analysis corresponding to this
area is 300 nm or more, this area is determined as a phosphoric acid-based coating.
20 Here, in addition to the above three elements which are determination elements for
specifying the phosphoric acid-based coating, the phosphoric acid-based coating may
contain aluminum, magnesium, nickel, manganese, or the like derived from a phosphate.
In addition, silicon derived from colloidal silica and the like may be contained. Here, in
the present embodiment, the phosphoric acid-based coating may not be provided.
25 [0082]
28
Regarding the area excluding the silicon steel sheet and the phosphoric acidbased
coating specified above, based on the observation results of COMPO images and
quantitative analysis results of SEM-EDS, if there is an area in which the Fe content is
less than 80 atom%, the P content is less than 5 atom%, the Si content is less than 20
5 atom%, the 0 content is 20 atom% or more, and the Al content is 10 atom% or more
excluding measurement noise, and the line segment (thickness) on the scan line for line
analysis corresponding to this area is 300 nm or more, this area is determined as an
aluminum borate-based coating. Here, in addition to the five elements which are
determination elements for specifying the aluminum borate-based coating, the aluminum
10 borate-based coating contains boron. However, it may be difficult to accurately analyze
the amount of boron by EDS quantitative analysis due to the influence of carbon and the
like. Therefore, as necessary, EDS qualitative analysis may be performed in order to
determine whether the aluminum borate-based coating contains boron. Here, in the
present embodiment, the aluminum borate-based coating may not be provided.
15 [0083]
When an area corresponding to the phosphoric acid-based coating or the
aluminum borate-based coating is determined, precipitates, inclusions, voids and the like
contained in each coating are not included as determination targets, and an area that
satisfies the above quantitative analysis results as a matrix phase is determined as a
20 phosphoric acid-based coating or an aluminum borate-based coating. For example,
based on the COMPO images or line analysis results, if it is confirmed that precipitates,
inclusions, voids and the like are present on the scan line for line analysis, this area is not
included in the target, and determination is performed by quantitative analysis results as a
matrix phase. Here, precipitates, inclusions, and voids can be distinguished from matrix
25 phases by contrast in the COMPO images, and can be distinguished from matrix phases
29
by the abundance of constituent elements in the quantitative analysis results. Here,
when the phosphoric acid-based coating or the aluminum borate-based coating is
specified, it is preferable to perform specification at a position on the scan line for line
analysis in which precipitates, inclusions, and voids are not included.
5 [0084]
If there is an area excluding the silicon steel sheet and the insulation coating (the
aluminum borate-based coating or the phosphoric acid-based coating) specified above
and the line segment (thickness) on the scan line for line analysis corresponding to this
area is 300 nm or more, this area is determined as an intermediate layer. Here, in the
10 present embodiment, the intermediate layer may not be provided.
[0085]
The intermediate layer may satisfy, as an overall average, an average Fe content
of less than 80 atom%, an average P content of less than 5 atom%, an average Si content
of 20 atom% or more, and an average 0 content of 30 atom% or more. In addition, if
15 the intermediate layer is not a forsterite coating but a silicon oxide film mainly
containing silicon oxide, the average Mg content of the intermediate layer may be less
than 20 atom%. Here, the quantitative analysis results of the intermediate layer are
quantitative analysis results as a matrix phase, which do not include analysis results of
precipitates, inclusions, voids, and the like contained in the intermediate layer. Here,
20 when the intermediate layer is specified, it is preferable to perform specification at a
position on the scan line for line analysis in which precipitates, inclusions, and voids are
not included.
[0086]
Specification of each layer and measurement of the thickness using the above
25 COMPO image observation and SEM-EDS quantitative analysis are performed at five or
30
more locations with different observation fields of view. For the thickness of each layer
obtained at five or more locations in total, an average value is obtained from values
excluding the maximum value and the minimum value, and this average value is used as
an average thickness of each layer. However, for the thickness of the intermediate layer,
5 thicknesses is measured at locations that can be determined as an external oxidation area
and not an internal oxidation area while observing the morphology, and an average value
of the thicknesses is obtained.
[0087]
Here, if there is a layer in which the line segment (thickness) on the scan line for
10 line analysis is less than 300 nm in at least one observation field of view at five or more
locations described above, the corresponding layer is observed in detail under a TEM,
and the corresponding layer is specified and the thickness thereof is measured using the
TEM.
15
[0088]
A test piece including a layer to be observed in detail using the TEM is cut out
by focused ion beam (FIB) processing so that the cutting direction is parallel to the sheet
thickness direction (specifically, a test piece is cut out so that the cut surface is parallel to
the sheet thickness direction and perpendicular to the rolling direction), and the crosssectional
structure of the cut surface is observed (bright-field image) by scanning-TEM
20 (STEM) at a magnification at which the corresponding layer is within the observation
field of view. When each layer is not within the observation field of view, the crosssectional
structure is observed in a plurality of continuous fields of view.
[0089]
In order to specify each layer in the cross-sectional structure, using TEM-EDS,
25 line analysis is performed in the sheet thickness direction, and quantitative analysis of
31
chemical components of each layer is performed. The elements to be quantitatively
analyzed are 6 elements: Fe, P, Si, 0, Mg, and Al. The device to be used is not
particularly limited, but in the present embodiment, for example, TEM (JEM-2100F
commercially available from JEOL Ltd.), EDS (JED-2300T commercially available from
5 JEOL Ltd.), and EDS analysis software (AnalysisStation commercially available from
JEOL Ltd.) may be used.
[0090]
Based on the bright-field image observation results obtained by the TEM and the
quantitative analysis results obtained by the TEM-EDS described above, each layer is
10 specified and the thickness of each layer is measured. The method of specifying each
layer and the method of measuring the thickness of each layer using the TEM may be
performed according to the above method using the SEM.
[0091]
Here, when the thickness of each layer specified using the TEM is 5 nm or less,
15 it is preferable to use a TEM having a spherical aberration correction function in
consideration of spatial resolution. In addition, when the thickness of each layer is 5 nm
or less, point analysis is performed in the sheet thickness direction, for example, at
intervals of 2 nm or less, the line segment (thickness) of each layer is measured, and this
line segment may be used as the thickness of each layer. For example, when the TEM
20 having a spherical aberration correction function is used, EDS analysis can be performed
with a spatial resolution of about 0.2 nm.
[0092]
Here, in the quantitative analysis results of the chemical components of the
phosphoric acid-based coating specified by the above method, if the Fe content is less
25 than 80 atom%, the P content is 5 atom% or more, and the 0 content is 30 atom% or
32
more, it is determined that the phosphoric acid-based coating mainly contains a
phosphorus silicon composite oxide.
[0093]
Similarly, in the quantitative analysis results of the chemical components of the
5 aluminum borate-based coating specified by the above method, if the Fe content is less
than 80 atom%, the P content is less than 5 atom%, the Si content is less than 20 atom%,
the 0 content is 20 atom% or more, and the Al content is 10 atom% or more, and boron
is detected by qualitative analysis, it is determined that the aluminum borate-based
coating mainly contains an aluminum/boron oxide.
10 [0094]
Similarly, in the quantitative analysis results of the chemical components of the
intermediate layer specified by the above method, if the average Fe content is less than
80 atom%, the average P content is less than 5 atom%, the average Si content is 20
atom% or more, the average 0 content is 30 atom% or more, and the average Mg content
15 is less than 20 atom%, it is determined that the intermediate layer mainly contains silicon
oxide.
[0095]
In the following method, it is determined whether the aluminum borate-based
coating contains aluminum oxide, AhsB4033, Al4B209, boron oxide or the like. A
20 sample is cut out from a grain-oriented electrical steel sheet, and as necessary, polishing
is performed so that a surface parallel to the sheet surface becomes a measurement
surface, the aluminum borate-based coating is exposed, and X-ray diffraction
measurement is performed. For example, X-ray diffraction may be performed using
CoKa rays (Ka1) as incident X rays. Based on X-ray diffraction patterns, it is identified
25 whether there is aluminum oxide, AhsB4033, Al4B209, boron oxide or the like.
33
[0096]
The above identification may be performed using a Powder Diffraction File
(PDF) of International Centre for Diffraction Data (ICDD). The identification of
aluminum oxide may be performed based on PDF: No. 00-047-1770, or 00-056-1186.
5 The identification of AhsB4033 may be performed based on PDF: No. 00-029-0009, 00-
053-1233, or 00-032-0003. The identification of Al4B209 may be performed based on
PDF: No. 00-029-0010. The identification of boron oxide may be performed based on
PDF: No. 00-044-1085, 00-024-0160, or 00-006-0634.
10
[0097]
Next, a method of producing a grain-oriented electrical steel sheet according to
the present embodiment will be described.
[0098]
Here, the method of producing a grain-oriented electrical steel sheet according
to the present embodiment is not limited to the following method. The following
15 production method is one example for producing the grain-oriented electrical steel sheet
according to the present embodiment.
[0099]
For example, the method of producing a grain-oriented electrical steel sheet
includes a casting process, a heating process, a hot rolling process, a hot-band annealing
20 process, a hot-band pickling process, a cold rolling process, a decarburization annealing
process, a nitriding process, an annealing separator applying process, a final annealing
process, a surface treatment process, an intermediate layer forming process, an insulation
coating forming process, and a magnetic domain controlling process.
[0100]
25 Since the grain-oriented electrical steel sheet according to the present
34
embodiment has surface properties of the silicon steel sheet as a base, among the above
processes of producing the grain-oriented electrical steel sheet, it is particularly
preferable to control four processes: the cold rolling process, the decarburization
annealing process, the final annealing process, and the surface treatment process which
5 affect the surface properties of the silicon steel sheet. Hereinafter, a preferable
production method will be described in order from the casting process.
[0101]
Casting process
In the casting process, steel having the above chemical components may be
10 melted in a converter furnace, an electric furnace or the like, and the molten steel may be
used to produce a slab. A slab may be produced by a continuous casting method or an
ingot may be produced using molten steel and the ingot may be bloomed to produce a
slab. In addition, a slab may be produced by another method. The thickness of the
slab is not particularly limited, and is, for example, 150 to 350 mm. The thickness of
15 the slab is preferably 220 to 280 mm. A so-called thin slab with a thickness of 10 to 70
mm may be used as the slab.
[0102]
Heating process
In the heating process, the slab may be put into a well-known heating furnace or
20 a well-known soaking furnace and heated. As one method of heating the slab, the slab
may be heated at 1 ,280°C or lower. When the heating temperature of the slab is set to
1,280°C or lower, it is possible to avoid various problems (the need for a dedicated
heating furnace, a large amount of molten scale, and the like) occurring, for example,
when heating is performed at a temperature higher than 1 ,280°C. The lower limit value
25 of the heating temperature of the slab is not particular! y limited. When the heating
35
temperature is too low, hot rolling may become difficult, and the productivity may
decrease. Therefore, the heating temperature may be set in a range of 1 ,280°C or lower
in consideration of productivity. The preferable lower limit of the heating temperature
of the slab is 1,1 00°C. The preferable upper limit of the heating temperature of the slab
5 is 1 ,250°C.
[0103]
In addition, as another method of heating a slab, the slab may be heated at a
temperature of 1,320°C or higher. When heating is performed at a high temperature of
1,320°C or higher, AlN and Mn (S, Se) dissolve and finely precipitate in the subsequent
10 process, and secondary recrystallization can be stably exhibited. Here, the slab heating
process itself may be omitted and hot rolling may start after casting and before the slab
temperature is lowered.
15
[0104]
Hot rolling process
In the hot rolling process, the slab may be hot-rolled using a hot rolling mill.
The hot rolling mill includes, for example, a rough rolling mill and a final rolling mill
disposed downstream from the rough rolling mill. The heated steel is rolled with the
rough rolling mill and then additionally rolled with the final rolling mill to produce a hotrolled
steel sheet. The final temperature (the steel sheet temperature on the outlet side
20 of the final rolling stand that finally rolls the steel sheet with the final rolling mill) in the
hot rolling process may be 700 to 1,150°C.
[0105]
Hot-band annealing process
In the hot-band annealing process, the hot-rolled steel sheet may be annealed
25 (hot-band annealing). In the hot-band annealing, the non-uniform structure occurring
36
during hot rolling is made as uniform as possible. The annealing conditions are not
particularly limited as long as the non-uniform structure occurring during hot rolling can
be made uniform. For example, the hot-rolled steel sheet is annealed under conditions
of a soaking temperature of 750 to 1 ,200°C and a soaking time of 30 to 600 seconds.
5 Here, it is not always necessary to perform hot-band annealing, and a determination of
whether the hot-band annealing process is performed may depend on characteristics
required for the finally produced grain -oriented electrical steel sheet and production cost.
In addition to make the structure uniform, in order to perform fine precipitation control of
an AlN inhibitor, and control solid solution carbon and the second phase, two-step
10 annealing, rapid cooling after annealing, and the like may be performed by a known
method.
[0106]
Hot-band pickling process
In the hot-band pickling process, pickling may be performed in order to remove
15 the scale generated on the surface of the hot-rolled steel sheet. Pickling conditions
during hot-band pickling are not particularly limited, and pickling may be performed
under known conditions.
[0107]
Cold rolling process
20 In the cold rolling process, the hot-rolled steel sheet may be subjected to cold
25
rolling once or twice or more with intermediate annealing therebetween. The final cold
ro! linf!. reduction rate in cold rolling (cumulative cold ro! linf!. reduction rate without
intermediate annealing or cumulative cold rolling reduction rate after intermediate
annealing is performed) is preferably 80% or more and more preferably 90% or more.
In addition, thr: f1n;:d rnld rollinp re~(hwtinn n1te In cold rolling is preferably
37
5
95% or less. Here, the final cold rolling reduction rate(%) is defined as follows.
Cold rollin£ reduction rate(% )=(1-sheet thickness of steel sheet after final cold
rolling/sheet thickness of steel sheet before final cold rolling)x100
[0108]
In the present embodiment, in the surface properties of the rolling roll in the
final pass (final stand) in cold rolling, the arithmetic average Ra is 0.40 ~m or less, and
more preferably, the average value ave-AMPcwo of amplitudes in a wavelength range of
20 to 100 ~m among the wavelength components obtained by performing Fourier
analysis is 0.050 ~m or less, and the rolling ratio in the final pass (final stand) is
10 preferably 10% or more. When the rolling roll of the final pass is smoother and the
rolling ratio of the final pass is larger, it ultimately becomes easier to smoothly control
the surface of the silicon steel sheet. When the above conditions are satisfied in cold
rolling and control conditions are satisfied in the postprocess, ave-AMPcwo and the like
of the silicon steel sheet can be suitably controlled.
15 [0109]
Decarburization annealing process
In the decarburization annealing process, the cold-rolled steel sheet may be
annealed in a decarburized atmosphere. Carbon in the steel sheet is removed by
decarburization annealing and primary recrystallization also occurs. In the
20 decarburization annealing, the oxidation degree (PH20/PH2) in the annealing atmosphere
(atmosphere in the furnace) may be 0.01 to 0.15, the soaking temperature may be 750 to
900°C, and the soaking time may be 10 to 600 seconds.
[0110]
In the present embodiment, the conditions for decarburization annealing
25 described above are controlled, and the amount of oxygen on the surface of the
38
decarburized and annealed sheet is controlled such that it is 1 g/m2 or less. For
example, when the oxidation degree is high within the above range, the soaking
temperature is lowered within the above range or the soaking time is shortened within the
above range, and the amount of oxygen on the surface of the steel sheet may be 1 g/m2 or
5 less. In addition, for example, when the soaking temperature is high within the above
range, the oxidation degree is lowered within the above range, or the soaking time is
shortened within the above range, and the amount of oxygen on the surface of the steel
sheet may be 1 g/m2 or less. Here, even if pickling is performed using sulfuric acid,
hydrochloric acid, or the like after decarburization annealing, it is not easy to control the
10 amount of oxygen on the surface of the decarburized and annealed sheet such that it is 1
g/m2 or less. It is preferable to control the amount of oxygen on the surface of the
decarburized and annealed sheet by controlling the conditions for decarburization
annealing described above.
[0111]
15 The amount of oxygen on the surface of the decarburized and annealed sheet is
preferably 0.8 g/m2 or less. When the amount of oxygen is smaller, it ultimately
becomes easier to smoothly control the surface of the silicon steel sheet. When the
above conditions are satisfied in the decarburization annealing process and control
conditions are satisfied in the preprocess and the postprocess, ave-AMPcwo and the like
20 of the silicon steel sheet can be suitably controlled.
[0112]
Nitriding process
In the nitriding process, the decarburized and annealed sheet may be annealed
and nitrided in the atmosphere containing ammonia. This nitriding treatment may be
25 continued immediate! y after decarburization annealing without lowering the temperature
39
5
of the steel sheet after decarburization annealing to room temperature. When the
nitriding treatment is performed, since fine inhibitors such as AlN and (Al, Si)N are
produced in the steel, secondary recrystallization can be stably exhibited.
[0113]
The nitriding treatment conditions are not particularly limited, but it is
preferable to perform nitriding so that the nitrogen content in the steel increases by
0.003% or more before and after nitriding. The increment of nitrogen before and after
nitriding is preferably 0.005% or more and more preferably 0.007% or more. When the
increment of nitrogen before and after nitriding is more than 0.030%, the effect is
10 maximized. Therefore, nitriding may be performed so that the increment of nitrogen is
0.030% or less.
[0114]
Annealing separator applying process
In the annealing separator applying process, an annealing separator containing
15 Ah03 and MgO is applied to the surface of the decarburized and annealed sheet, and the
applied annealing separator may be dried. The annealing separator may be applied to
the steel sheet surface by aqueous slurry coating, electrostatic coating, or the like.
[0115]
When the annealing separator mainly contains MgO and the amount of Ah03 is
20 small, a forsterite coating is formed on the steel sheet during final annealing. On the
other hand, when the annealing separator mainly contains Ah03 and the amount of MgO
is small, mullite (3Ah03 ·2Si02) is formed on the steel sheet. Since theses forsterite and
mullite hinder domain wall motion, iron loss characteristics of the grain -oriented
electrical steel sheet deteriorate.
25 [0116]
40
If an annealing separator containing Ah03 and MgO in a preferable ratio is used,
a steel sheet having a smooth surface without forming forsterite or mullite during final
annealing can be obtained. For example, the annealing separator may contain 5 to 50%
ofMgO/(MgO+Ah03) which is a mass ratio ofMgO andAh03 and 1.5 mass% or less of
5 hydration water.
[0117]
Final annealing process
In the final annealing process, the cold-rolled steel sheet to which the annealing
separator is applied may be subjected to final annealing. When the final annealing is
10 performed, secondary recrystallization occurs, and the crystal orientation of the steel
sheet accumulates in the { 110} <00 1 > orientation. In the heating procedure of final
annealing, when the annealing atmosphere (the atmosphere in the furnace) contains
hydrogen in order to stably perform secondary recrystallization, the oxidation degree
(PH20IPH2) is set to 0.0001 to 0.2, and in the case of an atmosphere containing an inert
15 gas not containing hydrogen, the dew point may be ooc or lower.
[0118]
In the present embodiment, regarding high temperature soaking conditions for
final annealing, in an atmosphere containing 50% volume or more of hydrogen, the
soaking temperature is 1,100 to 1 ,250°C. In addition, when the soaking temperature is
20 1,100 to 1,150°C, the soaking time is 30 hours or longer. In addition, when the soaking
temperature is higher than 1,150 to 1 ,250°C, the soaking time is 10 hours or longer.
When the soaking temperature is higher or the soaking time is longer, it ultimate! y
becomes easier to smoothly control the surface of the silicon steel sheet. However,
when the soaking temperature is higher than 1 ,250°C, equipment is expensive. When
25 the above conditions are satisfied in the final annealing process and control conditions
41
are satisfied in the preprocess and the postprocess, ave-AMPc10o and the like of the
silicon steel sheet can be suitably controlled.
[0119]
Here, in the final annealing, elements such as Al, N, S, and Se contained as a
5 steel composition in the cold-rolled steel sheet are discharged and the steel sheet is
purified.
[0120]
Surface treatment process
In the surface treatment process, the steel sheet after final annealing (finally
10 annealed steel sheet) may be pickled and then washed with water. The pickling
treatment and washing with water are performed to remove an excess annealing separator
that did not react with steel from the surface of the steel sheet, and the surface properties
of the steel sheet can be suitably controlled. Here, the steel sheet after the surface
treatment process is a silicon steel sheet as a base of the grain -oriented electrical steel
15 sheet.
[0121]
In the present embodiment, regarding pickling conditions for the surface
treatment, a solution containing a total amount of less than 20 mass% of one or two or
more of sulfuric acid, hydrochloric acid, phosphoric acid, nitric acid, chloric acid, a
20 chromium oxide aqueous solution, chromium sulfuric acid, permanganate, peroxosulfuric
acid and peroxophosphate is preferably used. 10 mass% or less is more preferable.
Using this solution, pickling is performed under conditions of a high temperature and a
short time. Specifically, pickling is performed when the temperature of the solution is
set to 50 to 80°C and the immersion time is set to 1 to 30 seconds. When pickling is
25 performed under such conditions, an excess annealing separator on the surface of the
42
steel sheet can be efficiently removed and the surface properties of the steel sheet can be
suitably controlled. Within the above range, when the acid concentration is lower, the
liquid temperature is lower, and the immersion time is shorter, etch pits formed on the
surface of the steel sheet are restricted and it ultimately becomes easier to smoothly
5 control the surface of the silicon steel sheet. When the above conditions are satisfied in
the surface treatment process and control conditions are satisfied in the preprocess, aveAMPcwo
and the like of the silicon steel sheet can be suitably controlled. Here,
conditions for washing with water in the surface treatment are not particular! y limited,
and washing may be performed under known conditions.
10 [0122]
In the present embodiment, the grain -oriented electrical steel sheet including the
silicon steel sheet produced above as a base may be produced. Specifically, a grainoriented
electrical steel sheet may be produced using a silicon steel sheet in which an
average value of amplitudes in a wavelength range of 20 to 100 ~m among the
15 wavelength components obtained by performing Fourier analysis on the measured crosssectional
curve parallel to the sheet width direction is 0.0001 to 0.050 ~mas a base.
Preferably, an intermediate layer and an insulation coating may be formed on the sheet
surface of the silicon steel sheet using the above silicon steel sheet as a base to produce a
grain-oriented electrical steel sheet.
20 [0123]
Intermediate layer forming process
In the intermediate layer forming process, the above silicon steel sheet may be
soaked in an atmospheric gas which contains hydrogen and has an oxidation degree
(PH20/PH2) that is adjusted to 0.00008 to 0.012 at a temperature range of 600°C or
25 higher and 1,150°C or lower for 10 seconds or longer and 100 seconds or shorter.
43
5
According to this heat treatment, an intermediate layer as an externally oxidized layer is
formed on the surface of the silicon steel sheet.
[0124]
Insulation coating forming process
In the insulation coating forming process, an insulation coating (a phosphoric
acid-based coating or an aluminum borate-based coating) may be formed on the silicon
steel sheet on which the intermediate layer is formed.
[0125]
When a phosphoric acid-based coating is formed, a composition for forming a
10 phosphoric acid-based coating containing a mixture of colloidal silica, a phosphate such
as a metal phosphate, and water is applied and baked. The composition for forming a
phosphoric acid-based coating may contain 25 to 75 mass% of a phosphate and 75 to 25
mass% of colloidal silica in terms of anhydrous. The phosphate may be an aluminum
salt, a magnesium salt, a nickel salt, a manganese salt or the like of phosphoric acid.
15 The phosphoric acid-based coating is formed by baking the composition for forming a
phosphoric acid-based coating at 350 to 600°C, and then heating at temperature of 800 to
1,000°C. During the heat treatment, as necessary, the oxidation degree and the dew
point and the like of the atmosphere may be controlled.
20
[0126]
When an aluminum borate-based coating is formed, a composition for forming
an aluminum borate-based coating containing alumina sol and boric acid is applied and
baked. The composition for forming an aluminum borate-based coating may have a
composition ratio between alumina sol and boric acid that is 1.25 to 1.81 as an atomic
ratio (Al/B) between aluminum and boric acid. The aluminum borate-based coating is
25 formed by performing heating with a soaking temperature of 750 to 1,350°C and a
44
5
soaking time of 10 to 100 seconds. During the heat treatment, as necessary, the
oxidation degree, the dew point and the like of the atmosphere may be controlled.
[0127]
Magnetic domain controlling process
In the magnetic domain controlling process, a treatment for refining the
magnetic domain of the silicon steel sheet may be performed. When non-destructive
stress strain is applied in a direction intersecting the rolling direction of the silicon steel
sheet or a physical groove is formed, the magnetic domain of the silicon steel sheet can
be refined. For example, the stress strain may be applied by laser beam irradiation,
10 electron beam irradiation, or the like. The groove may be provided by a mechanical
method such as a gear, a chemical method such as etching, or a thermal method such as
laser irradiation.
[0128]
When non-destructive stress strain is applied to the silicon steel sheet to refine
15 the magnetic domain, it is preferable to control the magnetic domain after the insulation
coating forming process. On the other hand, when a physical groove is formed in the
silicon steel sheet to refine the magnetic domain, it is preferable to control the magnetic
domain between the cold rolling process and the decarburization annealing process,
between the decarburization annealing process (nitriding process) and the annealing
20 separator applying process, between the intermediate layer forming process and the
insulation coating forming process, or after the insulation coating forming process.
[0129]
As described above, in the present embodiment, when conditions for four
processes including the cold rolling process, the decarburization annealing process, the
25 final annealing process, and the surface treatment process are controlled, the surface
45
properties of the silicon steel sheet can be controlled. Since conditions for these four
processes are each control conditions for controlling the surface properties of the silicon
steel sheet, it is not enough to satisfy only one condition. Unless these conditions are
controlled simultaneously and inseparably, ave-AMPc10o of the silicon steel sheet cannot
5 be satisfied.
[0130]
[Second embodiment]
In a grain -oriented electrical steel sheet according to the present embodiment, in
addition to optimally controlling the surface properties of the silicon steel sheet in the
10 sheet width direction (C direction), the surface properties of the silicon steel sheet in the
rolling direction (L direction) are also optimally controlled.
[0131]
For example, inside the transformer, when the magnetization direction matches
the easy magnetization direction of the grain-oriented electrical steel sheet, the iron loss
15 can be reduced. However, for example, in a 3-phase stacked transformer, since
magnetization directions are orthogonal to each other in aT-shaped bonding part, even if
a grain-oriented electrical steel sheet having excellent magnetic properties only in one
direction is used, the iron loss may not be reduced as expected. Therefore, particular! y,
in the T-shaped bonding part, it is necessary to improve magnetic properties of the silicon
20 steel sheet in the sheet width direction in addition to the rolling direction which is the
easy magnetization direction of the silicon steel sheet.
[0132]
Therefore, in the grain-oriented electrical steel sheet according to the present
embodiment, in addition to the sheet width direction (C direction) of the silicon steel
25 sheet, the surface properties are controlled in a wavelength range of 20 to 100 ~m also in
46
the rolling direction (L direction) of the silicon steel sheet.
[0133]
Specifically, when the maximum value of amplitudes in a wavelength range of
20 to 100 ~m among the wavelength components obtained by performing Fourier
5 analysis on the measured cross-sectional curve parallel to the sheet width direction of the
silicon steel sheet is set as max-AMPc10o and the maximum value of amplitudes in a
wavelength range of 20 to 100 ~m among the wavelength components obtained by
performing Fourier analysis on the measured cross-sectional curve parallel to the rolling
direction of the silicon steel sheet is set as max-AMPuoo, max-DIV 100, which is a value
10 obtained by dividing max-AMPc10o by max-AMPuoo, is controlled such that it is 1.5 to
6.0.
[0134]
Here, in the present embodiment, like the first embodiment, it is a prerequisite to
control ave-AMPc10o which corresponds to the surface properties of the silicon steel
15 sheet in the sheet width direction. Then, surface properties in the rolling direction are
also controlled. Therefore, the value of max-DIV 100 increases as the value of maxAMPuoo
in the rolling direction decreases with respect to max-AMPc10o in the sheet
width direction. When max-DIV 100 is 1.5 or more, it can be determined that surface
properties are sufficiently controlled not only in the sheet width direction but also in the
20 rolling direction. max-DIV 100 is preferably 2.0 or more and more preferably 3.0 or
more.
[0135]
On the other hand, the upper limit of max-DIV 100 is not particularly limited.
However, it is not industrially easy to control surface properties in the rolling direction so
25 that surface properties of the silicon steel sheet in the sheet width direction is controlled
47
and max-DIVwo is then larger than 6.0. Therefore, max-DIVwo may be 6.0 or less.
[0136]
In addition, when the maximum value of amplitudes in a wavelength range of 20
to 50 ~m among the wavelength components obtained by performing Fourier analysis on
5 the measured cross-sectional curve parallel to the sheet width direction of the silicon steel
sheet is set as max-AMPcso and the maximum value of amplitudes in a wavelength range
of 20 to 50 ~m among the wavelength components obtained by performing Fourier
analysis on the measured cross-sectional curve parallel to the rolling direction of the
silicon steel sheet is set as max-AMPLso, max-DIVso, which is a value obtained by
10 dividing max-AMPcso by max-AMPLso, is controlled such that it is 1.5 to 5.0.
[0137]
In order to suitably control surface properties in the rolling direction with
respect to the sheet width direction, max-DIVso is preferably 2.0 or more and more
preferably 3.0 or more. On the other hand, the upper limit ofmax-DIVso is not
15 particularly limited. However, it is not industrially easy to control surface properties in
the rolling direction so that the surface properties of the silicon steel sheet in the sheet
width direction is controlled and max-DIVso is then larger than 5.0. Therefore, maxDIV
so may be 5.0 or less.
20
[0138]
Fig. 3 shows a graph illustrating a plot of the amplitude with respect to the
wavelength from Fourier analysis of a measured cross-sectional curve parallel to a sheet
width direction and a rolling direction of a silicon steel sheet (base steel sheet), regarding
the grain-oriented electrical steel sheet according to the same embodiment. Generally,
in the rolled steel sheet, it is more difficult to control surface properties in the sheet width
25 direction than in the rolling direction. In the first embodiment, the surface properties of
48
the silicon steel sheet in the sheet width direction are controlled. However, in the
present embodiment, the surface properties of the silicon steel sheet in the rolling
direction are also controlled in addition to the sheet width direction. That is, as shown
in Fig. 3, regarding the wavelength range of 20 to 100 ~m, the amplitude in the sheet
5 width direction is optimized and the amplitude in the rolling direction is then reduced.
[0139]
For example, ave-AMPcwo, max-AMPcwo, max-AMPuoo, ave-AMPcso, maxAMPcso,
and max-AMPLso may be measured by the following method in the same
manner as in the measurement method in the first embodiment.
10 [0140]
When there is no coating on the silicon steel sheet, the surface properties of the
silicon steel sheet may be evaluated directly, and when there is a coating on the silicon
steel sheet, the surface properties of the silicon steel sheet may be evaluated after the
coating is removed. For example, the grain-oriented electrical steel sheet having a
15 coating may be immersed in an alkaline solution at a high temperature. Specifically,
immersion into a sodium hydroxide aqueous solution containing NaOH: 20 mass%+H20:
80 mass% is performed at 80°C for 20 minutes and washing with water and drying are
then performed, and thus the coating (the intermediate layer and the insulation coating)
on the silicon steel sheet can be removed. Here, the time for immersion in the sodium
20 hydroxide aqueous solution may be changed according to the thickness of the coating on
the silicon steel sheet.
[0141]
Regarding the surface properties of the silicon steel sheet, in a contact type
surface roughness measuring instrument, the contact needle tip radius is generally about
25 micron (~m), and a fine surface shape cannot be detected. Therefore, it is preferable to
49
5
use a non-contact type surface roughness measuring instrument. For example, a laser
type surface roughness measuring instrument (VK-9700 commercially available from
Keyence Corporation) may be used.
[0142]
First, measured cross-sectional curves in the sheet width direction and the
rolling direction of the silicon steel sheet are obtained using a non-contact type surface
roughness measuring instrument. When these measured cross-sectional curves are
obtained, one measurement length is 500 ~m or more, and a total measurement length is
5 mm or more. The spatial resolution in the measurement direction (the sheet width
10 direction of the silicon steel sheet) is 0.2 ~m or less. The measured cross-sectional
15
curves are subjected to Fourier analysis without applying a low pass or high pass filter to
the measured cross-sectional curves, that is, without cutting off a specific wavelength
component from the measured cross-sectional curves.
[0143]
Among the wavelength components obtained by performing Fourier analysis on
the measured cross-sectional curve, the average value and the maximum value of
amplitudes in a wavelength range of 20 to 100 ~m are obtained. The average value of
amplitudes in the sheet width direction is set as ave-AMPc10o, the maximum value of
amplitudes in the sheet width direction is set as max-AMPc10o, and the maximum value
20 of amplitudes in the rolling direction is set as max-AMPuoo. Similarly, among the
wavelength components obtained by performing Fourier analysis on the measured crosssectional
curve, the average value and the maximum value of amplitudes in a wavelength
range of 20 to 50 ~m are obtained. The average value of amplitudes in the sheet width
direction is set as ave-AMPcso, the maximum value of amplitudes in the sheet width
25 direction is set as max-AMPcso, and the maximum value of amplitudes in the rolling
50
5
direction is set as max-AMPLso. Here, the above measurement and analysis may be
performed at five or more locations while changing measurement locations, and the
average value thereof may be obtained
[0144]
In addition, max-DIV 100 is obtained by dividing max-AMPcwo by max-AMPuoo
obtained above. Similarly, max-DIVso is obtained by dividing max-AMPcso by maxAMPLso
obtained above.
[0145]
In the present embodiment, ave-AMPcwo is controlled and max-DIV 100 is then
10 controlled to improve iron loss characteristics. In addition, as necessary, ave-AMPcso is
controlled and max-D IV so is then controlled to suitably improve iron loss characteristics.
A method of controlling these ave-AMPcwo and max-DIV 100 will be described below.
[0146]
In addition, in the grain-oriented electrical steel sheet according to the present
15 embodiment, configurations other than the above surface properties are not particular! y
limited as in the first embodiment, descriptions thereof will be omitted here.
[0147]
Next, a method of producing a grain-oriented electrical steel sheet according to
the present embodiment will be described.
20 [0148]
Here, the method of producing a grain-oriented electrical steel sheet according
to the present embodiment is not limited to the following method. The following
production method is one example for producing the grain-oriented electrical steel sheet
according to the present embodiment.
25 [0149]
51
For example, the method of producing a grain-oriented electrical steel sheet
includes a casting process, a heating process, a hot rolling process, a hot-band annealing
process, a hot-band pickling process, a cold rolling process, a decarburization annealing
process, a nitriding process, an annealing separator applying process, a final annealing
5 process, a surface treatment process, an intermediate layer forming process, an insulation
coating forming process, and a magnetic domain controlling process.
However, since the casting process, the heating process, the hot rolling process,
the hot-band annealing process, the hot-band pickling process, the nitriding process, the
annealing separator applying process, the final annealing process, the intermediate layer
10 forming process, the insulation coating forming process, and the magnetic domain
controlling process are the same as those of the first embodiment, descriptions thereof
will be omitted here.
15
[0150]
Cold rolling process
In the cold rolling process according to the present embodiment, as in the first
embodiment, the final cold rolling ratio in cold rolling (cumulative cold rolling ratio
without intermediate annealing or cumulative cold rolling ratio after intermediate
annealing is performed) is preferably 80% or more and more preferably 90% or more.
In addition, the cold rolling ratio in final cold rolling is preferably 95% or less.
20 [0151]
In the present embodiment, in the surface properties of the rolling roll in the
final pass (final stand) in cold rolling, the arithmetic average Ra is 0.40 ~m or less, and
more preferably, the average value ave-AMPcwo of amplitudes in a wavelength range of
20 to 100 ~m among the wavelength components obtained by performing Fourier
25 analysis is 0.050 ~m or less, and the rolling ratio in the final pass (final stand) in cold
52
rolling is preferably 15% or more. When the rolling roll of the final pass is smoother
and the rolling ratio of the final pass is larger, it ultimately becomes easier to smoothly
control the surface of the silicon steel sheet. When the above conditions are satisfied in
cold rolling and control conditions are satisfied in the postprocess, ave-AMPc10o, max-
5 DIV 100 and the like of the silicon steel sheet can be suitably controlled.
[0152]
Decarburization annealing process
The same conditions as those of the first embodiment can be used as conditions
of the oxidation degree, the soaking temperature, and the soaking time of the
10 decarburization annealing process according to the present embodiment.
[0153]
In addition, in the present embodiment, the conditions for decarburization
annealing described above are controlled, and the amount of oxygen on the surface of the
decarburized and annealed sheet is controlled such that it is 0.95 g/m2 or less. For
15 example, when the oxidation degree is high within the above range, the soaking
temperature is lowered within the above range or the soaking time is shortened within the
above range, and the amount of oxygen on the surface of the steel sheet may be 0.95 g/m2
or less. In addition, for example, when the soaking temperature is high within the above
range, the oxidation degree is lowered within the above range, or the soaking time is
20 shortened within the above range, and the amount of oxygen on the surface of the steel
sheet may be 0.95 g/m2 or less. Here, even if pickling is performed using sulfuric acid,
hydrochloric acid, or the like after decarburization annealing, it is not easy to control the
amount of oxygen on the surface of the decarburized and annealed sheet such that it is
0.95 g/m2 or less. It is preferable to control the amount of oxygen on the surface of the
25 decarburized and annealed sheet by controlling the conditions for decarburization
53
annealing described above.
[0154]
The amount of oxygen on the surface of the decarburized and annealed sheet is
preferably 0.75 g/m2 or less. When the amount of oxygen is smaller, it ultimately
5 becomes easier to smoothly control the surface of the silicon steel sheet. When the
above conditions are satisfied in the decarburization annealing process and control
conditions are satisfied in the preprocess and the postprocess, ave-AMPcwo, max-DIV 100
and the like of the silicon steel sheet can be suitably controlled.
[0155]
10 Surface treatment process
In the present embodiment, regarding pickling conditions for the surface
treatment, a solution containing a total amount of 0 to less than 10 mass% of one or two
or more of sulfuric acid, hydrochloric acid, phosphoric acid, nitric acid, chloric acid, a
chromium oxide aqueous solution, chromium sulfuric acid, permanganate, peroxosulfuric
15 acid and peroxophosphate is preferably used. Using this solution, pickling is performed
under conditions of a high temperature and a short time. Specifically, pickling is
performed when the temperature of the solution is set to 50 to 80°C and the immersion
time is set to 1 to 30 seconds. When pickling is performed under such conditions, an
excess annealing separator on the surface of the steel sheet can be efficiently removed
20 and the surface properties of the steel sheet can be suitably controlled. Within the above
range, when the acid concentration is lower, the liquid temperature is lower, and the
immersion time is shorter, etch pits formed on the surface of the steel sheet are restricted
and it ultimately becomes easier to smoothly control the surface of the silicon steel sheet.
When the above conditions are satisfied in the surface treatment process and control
25 conditions are satisfied in the preprocess, ave-AMPcwo, max-DIV 100 and the like of the
54
5
silicon steel sheet can be suitably controlled. Here, conditions for washing with water
in the surface treatment are not particularly limited, and washing may be performed
under known conditions.
[0156]
In addition, in addition to the above pickling treatment and washing with water,
the surface properties of the steel sheet may be controlled using a brush roll. For
example, during brushing, an SiC having a 100th to SOOth abrasive grain size is used as
an abrasive material, the brush rolling reduction is 1.0 mm to 5.0 mm, and the brush
rotational speed is 500 to 1 ,500 rpm. In particular, when it is desired to control the
10 surface properties of the silicon steel sheet in the sheet width direction, brushing may be
performed so that the rotation axis is in the rolling direction. On the other hand, when it
is desired to control the surface properties of the silicon steel sheet in the rolling
direction, brushing may be performed so that the rotation axis is in the sheet width
direction. In order to control surface properties in the sheet width direction and the
15 rolling direction at the same time, brushing may be performed so that the rotation axis is
in both the sheet width direction and the rolling direction. When brushing is performed
so that the rotation axis is in the sheet width direction (direction orthogonal to the rolling
direction), max-DIV 100 of the silicon steel sheet can be suitably controlled.
20
[0157]
When the above conditions are satisfied in the surface treatment process and
control conditions are satisfied in the preprocess, ave-AMPc10o, max-DIV 100 and the like
of the silicon steel sheet can be suitably controlled. Here, conditions for washing with
water in the surface treatment are not particular! y limited, and washing may be
performed under known conditions.
25 [0158]
55
In the present embodiment, the grain -oriented electrical steel sheet including the
silicon steel sheet produced above as a base may be produced. Specifically, a grainoriented
electrical steel sheet may be produced using a silicon steel sheet having an aveAMPc10o
of 0.0001 to 0.050 ~m and max-DIV 100 of 1.5 to 6.0 as a base. Preferably, an
5 intermediate layer and an insulation coating may be formed on the sheet surface of the
silicon steel sheet using the above silicon steel sheet as a base to produce a grain-oriented
electrical steel sheet.
[0159]
In the present embodiment, when conditions for the above processes are
10 controlled, the surface properties of the silicon steel sheet can be controlled. Since
conditions for these processes are each control conditions for controlling the surface
properties of the silicon steel sheet, it is not enough to satisfy only one condition.
Unless these conditions are controlled simultaneously and inseparably, ave-AMPc10o,
max-DIV 100 and the like of the silicon steel sheet cannot be satisfied at the same time.
15 [Example 1]
[0160]
Next, effects of one aspect of the present invention will be described in more
detail with reference to examples, but conditions in the examples are one condition
example used for confirming the feasibility and effects of the present invention, and the
20 present invention is not limited to this one condition example. In the present invention,
various conditions can be used without departing from the gist of the present invention
and as long as the object of the present invention can be achieved.
[0161]
Molten steel having adjusted steel components was cast to produce a slab. The
25 slab was heated at 1,150°C, hot-rolled to have a sheet thickness of 2.6 mm, hot-band
56
annealed in two steps at 1,120°C+900°C, quenched after the hot-band annealing, pickled,
cold-rolled to have a sheet thickness of 0.23 mm, decarburized and annealed, and nitrided
and annealed so that the increment of nitrogen was 0.020%, and an annealing separator
containing Ah03 and MgO was applied, final annealing was performed, and a surface
5 treatment was then performed by pickling and washing with water.
[0162]
As production conditions, detailed conditions of the cold rolling process, the
decarburization annealing process, the final annealing process, and the surface treatment
process are shown in Table 1 to Table 3. In the cold rolling process, regarding the final
10 pass (final stand) of cold rolling, the rolling ratio and the roll roughness Ra were
changed. In the decarburization annealing process, the oxidation degree (PH20/PH2) in
the atmosphere, the soaking temperature, and the soaking time were changed, and the
amount of oxygen on the surface of the decarburized and annealed sheet was controlled.
Here, in the test No. 20, the oxidation degree in the atmosphere was 0.15, but the soaking
15 temperature was 880°C, and the soaking time was 550 seconds, and thus the amount of
oxygen on the surface of the decarburized and annealed sheet could not be controlled
such that it is 1 g/m2 or less. In the test No. 17, pickling was performed using sulfuric
acid immediately after the decarburization annealing process, but the amount of oxygen
on the surface of the decarburized and annealed sheet could not be controlled such that it
20 is 1 g/m2 or less.
[0163]
In addition, in the final annealing process, an atmosphere containing 50
volume% or more of hydrogen was used, and the soaking time was changed according to
the soaking temperature. In the surface treatment process, the acid concentration, the
25 liquid temperature, and the immersion time were changed for the pickling treatment.
57
Here, in the test No. 23, only washing with water was performed without performing the
pickling treatment.
[0164]
As the production results, the chemical components of the silicon steel sheets
5 and the surface properties of the silicon steel sheets are shown in Table 4 to Table 9.
Here, the chemical components and the surface properties of the silicon steel sheets were
determined based on the above method.
[0165]
In the tables, "-"in the chemical component of the silicon steel sheet indicates
10 that the alloying element is not intentionally added or the content is below the
measurement detection lower limit. In the tables, underlined values indicate that they
are outside the scope of the present invention. Here, all of the silicon steel sheets had
no forsterite coating and had a texture developed in the { 110} <00 1 > orientation.
15
[0166]
Using the produced silicon steel sheet as a base, on the sheet surface of the
silicon steel sheet, an intermediate layer was formed and an insulation coating was
formed, and magnetic domain control was performed to produce a grain-oriented
electrical steel sheet, and iron loss characteristics were evaluated. Here, the
intermediate layer was formed by performing a heat treatment in an atmosphere having
20 an oxidation degree (PH20IPH2) of 0.0012 at 850°C for 30 seconds. These intermediate
layers mainly contained silicon oxide and had an average thickness of 25 nm.
[0167]
In addition, in the test Nos. 1 to 10 and test Nos. 21 to 30, a phosphoric acidbased
coating was formed as an insulation coating. The phosphoric acid-based coating
25 was formed by applying a composition for forming a phosphoric acid-based coating
58
containing a mixture of colloidal silica, a phosphate of aluminum salt or magnesium salt,
and water, and performing a heat treatment under general conditions. These phosphoric
acid-based coatings mainly contained a phosphorus silicon composite oxide and had an
average thickness of 2 ~m.
5 [0168]
In addition, In the test Nos. 11 to 20 and test Nos. 31 to 42, an aluminum boratebased
coating was formed as an insulation coating. The aluminum borate-based coating
was formed by applying a composition for forming an aluminum borate-based coating
containing alumina sol and boric acid and performing a heat treatment under general
10 conditions. These aluminum borate-based coatings mainly contained aluminum/boron
oxide and had an average thickness of 2 ~m.
[0169]
In addition, in all of the grain-oriented electrical steel sheets, after the insulation
coating was formed, a laser beam was irradiated, and non-destructive stress strain was
15 applied to refine the magnetic domain.
[0170]
The iron loss was evaluated by a single sheet tester (SST). A sample with a
width of 60 mm and a length of 300 mm was collected from the produced grain-oriented
electrical steel sheet so that the long side of the test piece was in the rolling direction, and
20 W17 /50 (the iron loss when the steel sheet was magnetized with a magnetic flux density
of 1.7T at 50 Hz) was measured. When W17/50 was 0.68 W/kg or less, it was
determined that the iron loss was favorable.
[0171]
As shown in Table 1 to Table 9, in the examples of the present invention, since
25 the surface properties of the silicon steel sheets were suitably controlled, the iron loss
59
characteristics of the grain-oriented electrical steel sheets were excellent. On the other
hand, in the comparative examples, since the surface properties of the silicon steel sheets
were not suitably controlled, the iron loss characteristics of the grain-oriented electrical
steel sheets were not satisfied. Here, although not shown in the tables, for example, in
5 the test No. 5, in the sheet width direction of the silicon steel sheet, the surface roughness
Ra was 0.4 ~m or less when the cutoff wavelength J...c was 800 ~m, and the surface
roughness Ra was 0.2 ~m or less when the cutoff wavelength J...c was 20 ~m, but aveAMPcwo
was more than 0.050 ~m. In addition, in the test No. 39 and test No. 40, in the
sheet width direction of the silicon steel sheet, the surface roughness Ra was also 0.03
10 ~m when the cutoff wavelength J...c was 250 ~m, but in the test No. 39, ave-AMPcwo was
0.020 ~m or less, and in the test No. 40, ave-AMPcwo was more than 0.020 ~m.
[0172]
60
[Table 1]
Production conditions
Cold rolling process Decarburization annealing Final annealing process Surface treatment process
process
Final pass Final pass Atmosphere Surface Soaking Soaking Type of Concentration Liquid Immersion
reduction roll oxidation oxygen temperature oc time hour treatment of treatment temperature time sec
rate% roughness degree amount solution solution mass% of treatment
Ra~m g/m2 solution oc
Test 1 5 0.5 0.25 1.36 1,100 15 Sulfuric acid 30 90 90
Test 2 5 0.5 0.15 0.98 1,200 10 Sulfuric acid 25 90 60
Test 3 5 0.5 0.15 0.98 1,200 20 Sulfuric acid 20 90 60
Test 4 5 0.4 0.15 0.98 1,200 20 Sulfuric acid 20 90 60
Test 5 5 0.4 0.15 0.98 1,200 20 Sulfuric acid 10 80 30
Test 6 10 0.4 0.10 0.92 1,200 20 Sulfuric acid 3 80 30
Test 7 20 0.1 0.10 0.92 1,200 20 Sulfuric acid 0.50 70 15
Test 8 20 0.1 0.10 0.92 1,200 20 Sulfuric acid 5 70 15
Test 9 30 0.0025 0.09 0.88 1,150 30 Sulfuric acid 0.50 70 30
Test 30 0.1 0.09 0.88 1,250 10 Sulfuric acid 0.50 70 15
10
Test 11 20 0.1 0.09 0.88 1,200 20 Hydrochloric 5 70 15
acid
Test 20 0.1 0.09 0.88 1,200 20 Hydrochloric 5 60 15
12 acid
Test 20 0.1 0.09 0.88 1,200 20 Hydrochloric 0.50 70 15
13 acid
Test 20 0.1 0.09 0.88 1,200 20 Sulfuric 3+1 70 15
14 acid+phosphoric
acid
[0173]
[Table 2]
Production conditions
Cold rolling process Decarburization annealing Final annealing process Surface treatment process
61
process
Final Final pass Atmosphere Surface Soaking Soaking Type of treatment Concentration Liquid Immersion
pass roll oxidation oxygen temperature oc time hour solution of treatment temperature time sec
reduction roughness degree amount solution mass% of treatment
rate% Ra~m g/m2 solution oc
Test 20 0.1 0.09 0.88 1,200 20 Sulfuric acid 0.50 70 15
15
Test 5 0.5 0.10 0.92 1,200 20 Sulfuric acid 3 80 30
16
Test 10 0.4 0.17 1.07 1,200 20 Sulfuric acid 7.5 80 30
17
Test 10 0.4 0.10 0.92 1,200 20 Sulfuric acid 25 80 60
18
Test 10 0.5 0.10 0.92 1,200 20 Sulfuric acid 7.5 80 30
19
Test 10 0.4 0.15 1.10 1,200 20 Sulfuric acid 7.5 80 30
20
Test 10 0.4 0.15 0.98 1,100 20 Sulfuric acid 7.5 80 30
21
Test 10 0.4 0.10 0.92 1,200 5 Sulfuric acid 7.5 80 30
22
Test 10 0.4 0.10 0.92 1,200 20 Not applied Not applied Not applied Not applied
23
Test 10 0.4 0.15 0.98 1,200 20 Sulfuric acid 7.5 25 30
24
Test 10 0.4 0.10 0.92 1,200 20 Sulfuric acid 25 50 30
25
Test 20 0.1 0.09 0.89 1,200 20 Sulfuric acid 0.50 60 30
26
Test 20 0.1 0.09 0.90 1,200 20 Sulfuric acid 0.50 60 30
27
Test 20 0.1 0.09 0.88 1,200 20 Sulfuric acid 0.50 60 30
28
[0174]
[Table 3]
62
Production conditions
Cold rolling process Decarburization annealing Final annealing process Surface treatment process
process
Final Final pass Atmosphere Surface Soaking Soaking Type of treatment Concentration Liquid Immersion
pass roll oxidation oxygen temperature oc time hour solution of treatment temperature time sec
reduction roughness degree amount solution mass% of treatment
rate% Ra~m g/m2 solution oc
Test 20 0.1 0.09 0.89 1,200 20 Sulfuric acid 0.50 60 30
29
Test 20 0.1 0.09 0.87 1,200 20 Sulfuric acid 0.50 60 30
30
Test 20 0.1 0.09 0.87 1,200 20 Sulfuric acid 0.50 60 30
31
Test 20 0.1 0.09 0.89 1,200 20 Sulfuric acid 0.50 60 30
32
Test 20 0.1 0.09 0.88 1,200 20 Sulfuric acid 0.50 60 30
33
Test 20 0.1 0.09 0.89 1,200 20 Sulfuric acid 0.50 60 30
34
Test 20 0.1 0.09 0.88 1,200 20 Sulfuric acid 0.50 60 30
35
Test 20 0.1 0.09 0.87 1,200 20 Sulfuric acid 0.50 60 30
36
Test 20 0.1 0.09 0.88 1,200 20 Sulfuric acid 0.50 60 30
37
Test 20 0.1 0.09 0.90 1,200 20 Sulfuric acid 0.50 60 30
38
Test 30 0.1 0.02 0.30 1,250 30 Sulfuric acid 0.30 70 15
39
Test 25 0.1 0.01 0.35 1,250 30 Sulfuric acid 0.30 60 15
40
Test 8 0.4 0.10 0.92 1,150 30 Sulfuric acid 3 70 15
41
Test 10 0.4 0.10 0.92 1,150 30 Sulfuric acid 10 70 15
42
63
[0175]
[Table 4]
Production results
Component composition of silicon steel sheet (unit: mass%, remainder being Fe and impurities)
Si Mn Cr Cu p Sn Sb Ni B v Nb Mo Ti Bi Al c N s Se
Test 3.2 - - - - - - - - - - - - - 0.001 0.0004 0.0022 0.0027 -
1
Test 3.2 - - - - - - - - - - - - - 0.001 0.0008 0.0012 0.0025 -
2
Test 3.2 - - - - - - - - - - - - - 0.001 0.0008 0.0010 0.0014 -
3
Test 3.2 - - - - - - - - - - - - - 0.001 0.0008 0.0011 0.0014 -
4
Test 3.2 - - - - - - - - - - - - - 0.001 0.0008 0.0010 0.0014 -
5
Test 3.2 - - - - - - - - - - - - - 0.001 0.0011 0.0009 0.0014 -
6
Test 3.2 - - - - - - - - - - - - - 0.001 0.0011 0.0010 0.0014 -
7
Test 3.2 - - - - - - - - - - - - - 0.001 0.0011 0.0011 0.0013 -
8
Test 3.2 - - - - - - - - - - - - - 0.001 0.0012 0.0013 0.0025 -
9
Test 3.2 - - - - - - - - - - - - - 0.001 0.0010 0.0004 0.0012 -
10
Test 3.2 - - - - - - - - - - - - - 0.001 0.0013 0.0009 0.0014 -
11
Test 3.2 - - - - - - - - - - - - - 0.001 0.0013 0.0010 0.0013 -
64
12
Test 3.2 - - - - - - - - - - - - - 0.001 0.0013 0.0009 0.0014 -
13
Test 3.2 - - - - - - - - - - - - - 0.001 0.0013 0.0008 0.0014 -
14
[0176]
[Table 5]
Production results
Component composition of silicon steel sheet (unit: mass%, remainder being Fe and impurities)
Si Mn Cr Cu p Sn Sb Ni B v Nb Mo Ti Bi Al c N s Se
Test 3.2 - - - - - - - - - - - - - 0.001 0.0013 0.0010 0.0014 -
15
Test 3.2 - - - - - - - - - - - - - 0.001 0.0010 0.0009 0.0013 -
16
Test 3.2 - - - - - - - - - - - - - 0.001 0.0007 0.0010 0.0014 -
17
Test 3.2 - - - - - - - - - - - - - 0.001 0.0010 0.0010 0.0014 -
18
Test 3.2 - - - - - - - - - - - - - 0.001 0.0008 0.0006 0.0013 -
19
Test 3.2 - - - - - - - - - - - - - 0.001 0.0008 0.0006 0.0013 -
20
Test 3.2 - - - - - - - - - - - - - 0.001 0.0007 0.0006 0.0013 -
21
Test 3.2 - - - - - - - - - - - - - 0.001 0.0007 0.0007 0.0014 -
22
Test 3.2 - - - - - - - - - - - - - 0.001 0.0008 0.0006 0.0014 -
23
65
Test 3.2 - - - - - - - - - - - - - 0.001 0.0009 0.0005 0.0014 -
24
Test 3.2 - - - - - - - - - - - - - 0.001 0.0008 0.0006 0.0013 -
25
Test 3.3 0.1 - - - - - - - - - - - - 0.001 0.0008 0.0006 0.0014 -
26
Test 3.3 - 0.1 - - - - - - - - - - - 0.001 0.0009 0.0011 0.0007 0.0017
27
Test 3.3 - - 0.1 - - - - - - - - - - 0.001 0.0012 0.0010 0.0014 -
28
[0177]
[Table 6]
Production results
Component composition of silicon steel sheet (unit: mass%, remainder being Fe and impurities)
Si Mn Cr Cu p Sn Sb Ni B v Nb Mo Ti Bi Al c N s Se
Test 3.3 - - - 0.01 - - - - - - - - - 0.001 0.0008 0.0006 0.0014 -
29
Test 3.3 - - - - 0.05 - - - - - - - - 0.001 0.0008 0.0011 0.0006 0.0017
30
Test 3.3 - - - - - 0.03 - - - - - - - 0.001 0.0009 0.0009 0.0014 -
31
Test 3.3 - - - - - - 0.05 - - - - - - 0.001 0.0013 0.0010 0.0009 0.0016
32
Test 3.3 - - - - - - - 0.002 - - - - - 0.001 0.0013 0.0011 0.0008 0.0015
33
Test 3.3 - - - - - - - - 0.02 - - - - 0.002 0.0014 0.0010 0.0014 -
34
Test 3.3 - - - - - - - - - 0.03 - - - 0.001 0.0013 0.0009 0.0013 -
66
35
Test 3.3 - - - - - - - - - - 0.02 - - 0.001 0.0008 0.0006 0.0014 -
36
Test 3.3 - - - - - - - - - - - 0.005 - 0.001 0.0014 0.0009 0.0014 -
37
Test 3.3 - - - - - - - - - - - - 0.003 0.001 0.0013 0.0010 0.0008 0.0016
38
Test 3.2 - - - - - - - - - - - - - 0.001 0.0017 0.0003 0.0008 -
39
Test 3.2 - - - - - - - - - - - - - 0.001 0.0020 0.0004 0.0012 -
40
Test 3.2 - - - - - - - - - - - - - 0.001 0.0010 0.0013 0.0014 -
41
Test 3.2 - - - - - - - - - - - - - 0.001 0.0010 0.0012 0.0014 -
42
[0178]
[Table 7]
Production results Evaluation results Note
Surface properties of silicon steel sheet Iron loss W11;so W/kg
ave-AMPc10o J.!m ave-AMPcso J.!m
Test 1 0.247 0.234 0.79 Comparative example
Test 2 0.137 0.130 0.74 Comparative example
Test 3 0.060 0.044 0.72 Comparative example
Test 4 0.059 0.043 0.71 Comparative example
Test 5 0.052 0.038 0.70 Comparative example
Test 6 0.049 0.036 0.68 Example of present
invention
Test 7 0.025 0.017 0.63 Example of present
67
invention
Test 8 0.033 0.024 0.66 Example of present
invention
Test 9 0.029 0.020 0.65 Example of present
invention
Test 10 0.023 0.016 0.62 Example of present
invention
Test 11 0.034 0.023 0.67 Example of present
invention
Test 12 0.028 0.019 0.63 Example of present
invention
Test 13 0.026 0.018 0.63 Example of present
invention
Test 14 0.031 0.021 0.67 Example of present
invention
[0179]
[Table 8]
Production results Evaluation results Note
Surface properties of silicon steel sheet Iron loss W11;so W/kg
ave-AMPc10o J.!m ave-AMPcso J.!m
Test 15 0.026 0.018 0.63 Example of present
invention
Test 16 0.061 0.045 0.72 Comparative example
Test 17 0.184 0.134 0.77 Comparative example
Test 18 0.098 0.072 0.73 Comparative example
Test 19 0.066 0.048 0.71 Comparative example
Test 20 0.178 0.130 0.78 Comparative example
Test 21 0.053 0.039 0.71 Comparative example
68
Test 22 0.054 0.040 0.72 Comparative example
Test 23 0.121 0.088 0.82 Comparative example
Test 24 0.092 0.067 0.72 Comparative example
Test 25 0.089 0.065 0.71 Comparative example
Test 26 0.026 0.017 0.63 Example of present
invention
Test 27 0.025 0.017 0.63 Example of present
invention
Test 28 0.025 0.016 0.63 Example of present
invention
[0180]
[Table 9]
Production results Evaluation results Note
Surface properties of silicon steel sheet Iron loss W11;so W/kg
ave-AMPc10o J.!m ave-AMPcso J.!m
Test 29 0.026 0.018 0.64 Example of present
invention
Test 30 0.023 0.016 0.62 Example of present
invention
Test 31 0.024 0.016 0.62 Example of present
invention
Test 32 0.026 0.018 0.63 Example of present
invention
Test 33 0.025 0.017 0.62 Example of present
invention
Test 34 0.026 0.018 0.64 Example of present
invention
Test 35 0.027 0.019 0.63 Example of present
69
invention
Test 36 0.025 0.017 0.63 Example of present
invention
Test 37 0.024 0.016 0.63 Example of present
invention
Test 38 0.025 0.017 0.62 Example of present
invention
Test 39 0.018 0.012 0.60 Example of present
invention
Test 40 0.021 0.014 0.61 Example of present
invention
Test 41 0.051 0.037 0.71 Comparative example
Test 42 0.048 0.035 0.68 Example of present
invention
70
[Example 2]
[0181]
Molten steel having adjusted steel components was cast to produce a slab. The
slab was heated at 1,150°C, hot-rolled to have a sheet thickness of 2.6 mm, hot-band
5 annealed in two steps at 1,120°C+900°C, quenched after the hot-band annealing, pickled,
cold-rolled to have a sheet thickness of 0.23 mm, decarburized and annealed, and nitrided
and annealed so that the increment of nitrogen was 0.020%, and an annealing separator
containing Ah03 and MgO was applied, final annealing was performed, and a surface
treatment was then performed to perform at least one of pickling, washing with water,
10 and brushing.
[0182]
As production conditions, detailed conditions of the cold rolling process, the
decarburization annealing process, the final annealing process, and the surface treatment
process are shown in Table 10 to Table 13. In the cold rolling process, regarding the
15 final pass (final stand) of cold rolling, the rolling ratio and the roll roughness Ra were
changed. In the decarburization annealing process, the oxidation degree (PH20/PH2) in
the atmosphere, the soaking temperature, and the soaking time were changed, and the
amount of oxygen on the surface of the decarburized and annealed sheet was controlled.
Here, in the test No. 2-22, pickling was performed using sulfuric acid immediately after
20 the decarburization annealing process, but the amount of oxygen on the surface of the
decarburized and annealed sheet could not be controlled such that it is 1 g/m2 or less.
[0183]
In addition, in the final annealing process, an atmosphere containing 50
volume% or more of hydrogen was used, and the soaking time was changed according to
25 the soaking temperature. In the surface treatment process, the acid concentration, the
71
5
10
liquid temperature, and the immersion time were changed for the pickling treatment.
Here, in the test No. 2-43, washing with water and brushing were performed without
performing the pickling treatment.
[0184]
As the production results, the chemical components of the silicon steel sheets
and the surface properties of the silicon steel sheets are shown in Table 14 to Table 21.
Here, the chemical components and the surface properties of the silicon steel sheets were
determined based on the above method.
[0185]
In the tables, "-"in the chemical component of the silicon steel sheet indicates
that the alloying element is not intentionally added or the content is below the
measurement detection lower limit. In the tables, underlined values indicate that they
are outside the scope of the present invention. Here, all of the silicon steel sheets had
no forsterite coating and had a texture developed in the { 110} <00 1 > orientation.
15 [0186]
Using the produced silicon steel sheet as a base, on the sheet surface of the
silicon steel sheet, an intermediate layer was formed and an insulation coating was
formed, and magnetic domain control was performed to produce a grain-oriented
electrical steel sheet, and iron loss characteristics were evaluated. Here, the
20 intermediate layer was formed by performing a heat treatment in an atmosphere having
an oxidation degree (PH20/PH2) of 0.0012 at 850°C for 30 seconds. These intermediate
layers mainly contained silicon oxide and had an average thickness of 25 nm.
[0187]
In addition, in the test Nos. 2-1 to 2-15 and test Nos. 2-31 to 2-40, a phosphoric
25 acid-based coating was formed as an insulation coating. The phosphoric acid-based
72
coating was formed by applying a composition for forming a phosphoric acid-based
coating containing a mixture of colloidal silica, a phosphate of aluminum salt or
magnesium salt, and water, and performing a heat treatment under general conditions.
These phosphoric acid-based coatings mainly contained a phosphorus silicon composite
5 oxide and had an average thickness of 2 ~m.
[0188]
In addition, in the test Nos. 2-16 to 2-30 and test Nos. 2-41 to 2-55, an
aluminum borate-based coating was formed as an insulation coating. The aluminum
borate-based coating was formed by applying a composition for forming an aluminum
10 borate-based coating containing alumina sol and boric acid and performing a heat
treatment under general conditions. These aluminum borate-based coatings mainly
contained aluminum/boron oxide and had an average thickness of 2 ~m.
[0189]
In addition, in all of the grain-oriented electrical steel sheets, after the insulation
15 coating was formed, a laser beam was irradiated, and non-destructive stress strain was
applied to refine the magnetic domain.
[0190]
The iron loss was evaluated by a single sheet tester (SST). A sample with a
width of 60 mm and a length of 300 mm was collected from the produced grain-oriented
20 electrical steel sheet so that the long side of the test piece was in the rolling direction and
the sheet width direction, W17 /50 (the iron loss when the steel sheet was magnetized
with a magnetic flux density of 1. 7T at 50 Hz) was measured using the test piece in the
rolling direction, and W6/50 (the iron loss when the steel sheet was magnetized with a
magnetic flux density of 0.6T at 50 Hz) was measured using the test piece in the sheet
25 width direction. When the iron loss W17 /50 in the rolling direction was 0.68 W /kg or
73
less and the iron lossW6/50 in the sheet width direction was 0.80 W/kg or less, it was
determined that the iron loss was favorable.
[0191]
As shown in Table 10 to Table 21, in the examples of the present invention,
5 since the surface properties of the silicon steel sheets were suitably controlled, the iron
loss characteristics of the grain-oriented electrical steel sheets were excellent. On the
other hand, in the comparative examples, since the surface properties of the silicon steel
sheets were not suitably controlled, the iron loss characteristics of the grain -oriented
electrical steel sheets were not satisfied. Here, although not shown in the tables, for
10 example, in the test No. 2-3, in the sheet width direction of the silicon steel sheet, the
surface roughness Ra was 0.4 ~m or less when the cutoff wavelength J...c was 800 ~m, and
the surface roughness Ra was 0.2 ~m or less when the cutoff wavelength J...c was 20 ~m,
but ave-AMPc10o was more than 0.050 ~m. In addition, in the test No. 2-54 and test No.
2-55, in the sheet width direction of the silicon steel sheet, the surface roughness Ra was
15 also 0.03 ~m when the cutoff wavelength J...c was 250 ~m, but in the test No. 2-54, aveAMPclOo
was 0.020 ~m or less, and in the test No. 2-55, ave-AMPc10o was more than
0.020 ~m.
[0192]
74
[Table 10]
Production conditions
Cold rolling process Decarburization Final annealing process Surface treatment process
annealing rocess
Final Final pass Oxidation Surface Soaking Soaking Pickling treatment Brushing treatment
pass roll degree in oxygen temperature °C time Type of Concentration Liquid Immersion Done Abrasive Brush Brush
reduction roughness atmosphere amount hour treatment of treatment temperature time sec (Rotation grain size rolling rotational
rate% Ra11m g/m2 solution solution of axis reduction speed rpm
mass% treatment direction) mm
solution °C /Not
done
Test 5 0.5 0.15 0.98 1,200 20 Sulfuric 20 90 60 Not done - - -
2-1 acid
Test 5 0.4 0.15 0.98 1,200 20 Sulfuric 20 90 60 Not done - - -
2-2 acid
Test 5 0.4 0.15 0.98 1,200 20 Sulfuric 10 80 30 Not done - - -
2-3 acid
Test 15 0.4 0.10 0.92 1,200 20 Sulfuric 3 80 30 Sheet 500 3 750
2-4 acid width
direction
Test 15 0.4 0.10 0.92 1,200 20 Sulfuric 0.5 70 30 Sheet 500 3 750
2-5 acid width
direction
Test 15 0.1 0.12 0.95 1,200 20 Sulfuric 2 70 30 Sheet 500 3 750
2-6 acid width
direction
Test 20 0.1 0.10 0.92 1,200 20 Sulfuric 0.5 70 15 Sheet 500 3 750
2-7 acid width
direction
Test 15 0.1 0.12 0.95 1,200 20 Sulfuric 2 80 30 Rolling 500 2 1,000
2-8 acid direction
Test 15 0.1 0.12 0.95 1,200 20 Sulfuric 2 80 30 Sheet 500 2 500
2-9 acid width
direction
Test 15 0.1 0.12 0.95 1,200 20 Sulfuric 2 80 30 Sheet 500 4 1,500
2- acid width
10 direction
Test 15 0.4 0.10 0.92 1,200 20 Sulfuric 0.5 60 30 Rolling 500 4 1,000
2-11 acid direction
Test 15 0.4 0.10 0.92 1,200 20 Sulfuric 0.5 60 30 Sheet 500 4 500
2- acid width
12 direction
Test 15 0.4 0.10 0.92 1,200 20 Sulfuric 0.5 60 30 Sheet 500 3 750
75
2- acid width
13 direction
Test 30 0.1 0.09 0.88 1,150 30 Sulfuric 0.5 70 30 Sheet 500 3 750
2- acid width
14 direction
[0193]
[Table 11]
Production conditions
Cold rolling process Decarburization Final annealing process Surface treatment process
annealing process
Final Final pass Oxidation Surface Soaking Soaking Pickling treatment Brushing treatment
pass roll degree in oxygen temperature °C time Type of Concentration Liquid Immersion Done Abrasive Brush Brush
reduction roughness atmosphere amount hour treatment of treatment temperature time sec (Rotation grain rolling rotational
rate% Ra11m g/m2 solution solution of treatment axis size reduction speed
mass% solution °C direction) mm rpm
/Not
done
Test 30 0.1 0.09 0.88 1,250 10 Sulfuric acid 0.5 70 15 Sheet 500 3 750
2- width
15 direction
Test 20 0.1 0.09 0.88 1,200 20 Hydrochloric 5 70 15 Sheet 500 3 750
2- acid width
16 direction
Test 20 0.1 0.09 0.88 1,200 20 Hydrochloric 5 60 15 Sheet 500 3 750
2- acid width
17 direction
Test 20 0.1 0.09 0.88 1,200 20 Hydrochloric 0.5 70 15 Sheet 500 3 750
2- acid width
18 direction
Test 20 0.1 0.09 0.88 1,200 20 Sulfuric 3+1 70 15 Sheet 500 3 750
2- acid+ width
19 phosphoric direction
acid
Test 20 0.1 0.09 0.88 1,200 20 Sulfuric acid 0.5 70 15 Sheet 500 3 750
2- width
20 direction
Test 5 0.5 0.10 0.92 1,200 20 Sulfuric acid 3 80 30 Not done - - -
2-
21
Test 10 0.4 0.17 1.07 1,200 20 Sulfuric acid 7.5 80 30 Not done - - -
2-
76
22
Test 10 0.4 0.10 0.92 1,200 20 Sulfuric acid 25 80 60 Not done - - -
2-
23
Test 20 0.1 0.09 0.89 1,200 20 Sulfuric acid 0.5 60 30 Sheet 500 3 750
2- width
24 direction
Test 20 0.1 0.09 0.90 1,200 20 Sulfuric acid 0.5 60 30 Sheet 500 3 750
2- width
25 direction
Test 20 0.1 0.09 0.88 1,200 20 Sulfuric acid 0.5 60 30 Sheet 500 3 750
2- width
26 direction
Test 20 0.1 0.09 0.89 1,200 20 Sulfuric acid 0.5 60 30 Sheet 500 3 750
2- width
27 direction
Test 20 0.1 0.09 0.87 1,200 20 Sulfuric acid 0.5 60 30 Sheet 500 3 750
2- width
28 direction
[0194]
[Table 12]
Production conditions
Cold rolling process Decarburization Final annealing process Surface treatment process
annealing process
Final Final pass Oxidation Surface Soaking Soaking Pickling treatment Brushing treatment
pass roll degree in oxygen temperature °C time Type of Concentration Liquid Immersion Done Abrasive Brush Brush
reduction roughness atmosphere amount hour treatment of treatment temperature time sec (Rotation grain size rolling rotational
rate% Ra11m g/m2 solution solution of treatment axis reduction speed rpm
mass% solution °C direction) mm
/Not
done
Test 20 0.1 0.09 0.87 1,200 20 Sulfuric 0.5 60 30 Sheet 500 3 750
2- acid width
29 direction
Test 20 0.1 0.09 0.89 1,200 20 Sulfuric 0.5 60 30 Sheet 500 3 750
2- acid width
30 direction
Test 20 0.1 0.09 0.88 1,200 20 Sulfuric 0.5 60 30 Sheet 500 3 750
2- acid width
31 direction
Test 20 0.1 0.09 0.89 1,200 20 Sulfuric 0.5 60 30 Sheet 500 3 750
77
2- acid width
32 direction
Test 20 0.1 0.09 0.88 1,200 20 Sulfuric 0.5 60 30 Sheet 500 3 750
2- acid width
33 direction
Test 20 0.1 0.09 0.87 1,200 20 Sulfuric 0.5 60 30 Sheet 500 3 750
2- acid width
34 direction
Test 20 0.1 0.09 0.88 1,200 20 Sulfuric 0.5 60 30 Sheet 500 3 750
2- acid width
35 direction
Test 20 0.1 0.09 0.90 1,200 20 Sulfuric 0.5 60 30 Sheet 500 3 750
2- acid width
36 direction
Test 15 0.4 0.10 0.92 1,200 20 Sulfuric 3 80 30 Not done - - -
2- acid
37
Test 15 0.4 0.12 0.96 1,200 20 Sulfuric 2 80 30 Sheet 500 3 750
2- acid width
38 direction
Test 15 0.5 0.10 0.92 1,200 20 Sulfuric 7.5 80 30 Sheet 500 3 750
2- acid width
39 direction
Test 15 0.4 0.17 1.10 1,100 20 Sulfuric 7.5 80 30 Sheet 500 3 750
2- acid width
40 direction
Test 15 0.4 0.15 0.95 1,100 20 Sulfuric 7.5 80 30 Sheet 500 3 750
2- acid width
41 direction
Test 15 0.4 0.10 0.92 1,200 5 Sulfuric 7.5 80 30 Sheet 500 3 750
2- acid width
42 direction
[0195]
[Table 13]
Production conditions
Cold rolling process Decarburization Final annealing process Surface treatment process
annealing Jrocess
Final Final pass Oxidation Surface Soaking Soaking Pickling treatment Brushin~ treatment
pass roll degree in oxygen temperature °C time Type of I Conccntrat;on I Uqu;d I lmmcrs;on Done I Ahras;vc Brush I Brush
reduction roughness atmosphere amount hour treatment of treatment temperature time sec (Rot~tion grain size rolling rotational
rate% Ra11m g/m2 solution solution of treatment ax1s reduction speed rpm
78
mass% solution °C direction) mm
/Not
done
Test 15 0.4 0.10 0.92 1,200 20 Not Not applied Not applied Not Sheet 500 3 750
2- applied applied width
43 direction
Test 15 0.4 0.15 0.95 1,200 20 Sulfuric 7.5 25 15 Sheet 500 3 750
2- acid width
44 direction
Test 15 0.4 0.10 0.92 1,200 20 Sulfuric 25 50 30 Sheet 500 3 750
2- acid width
45 direction
Test 10 0.4 0.10 0.92 1,150 30 Sulfuric 3 70 15 Sheet 500 3 750
2- acid width
46 direction
Test 15 0.4 0.10 0.92 1,200 20 Sulfuric 0.5 70 30 Sheet 50 3 750
2- acid width
47 direction
Test 15 0.4 0.10 0.92 1,200 20 Sulfuric 0.5 70 30 Sheet 600 3 750
2- acid width
48 direction
Test 15 0.4 0.10 0.92 1,200 20 Sulfuric 0.5 70 30 Sheet 500 0.5 750
2- acid width
49 direction
Test 15 0.4 0.10 0.92 1,200 20 Sulfuric 0.5 70 30 Sheet 500 6 750
2- acid width
50 direction
Test 15 0.4 0.10 0.92 1,200 20 Sulfuric 0.5 70 30 Sheet 500 3 400
2- acid width
51 direction
Test 15 0.4 0.10 0.92 1,200 20 Sulfuric 0.5 70 30 Sheet 500 3 1,800
2- acid width
52 direction
Test 15 0.4 0.10 0.92 1,150 30 Sulfuric 7.5 70 15 Sheet 500 3 750
2- acid width
53 direction
Test 30 0.1 0.02 0.30 1,250 30 Sulfuric 0.3 70 15 Sheet 500 2 500
2- acid width
54 direction
Test 25 0.1 0.01 0.35 1,250 30 Sulfuric 0.3 60 15 Sheet 500 2 500
2- acid width
55 direction
[0196]
79
[Table 14]
Production results
Component composition of silicon steel sheet (unit: mass%, remainder being Fe and impurities)
Si Mn Cr Cu p Sn Sb Ni B v Nb Mo Ti Bi Al c N s Se
Test 3.2 - - - - - - - - - - - - - 0.001 0.0008 0.0011 0.0014 -
2-1
Test 3.2 - - - - - - - - - - - - - 0.001 0.0009 0.0012 0.0012 -
2-2
Test 3.2 - - - - - - - - - - - - - 0.001 0.0010 0.0009 0.0013 -
2-3
Test 3.2 - - - - - - - - - - - - - 0.001 0.0012 0.0012 0.0014 -
2-4
Test 3.2 - - - - - - - - - - - - - 0.001 0.0013 0.0010 0.0013 -
2-5
Test 3.2 - - - - - - - - - - - - - 0.001 0.0011 0.0011 0.0014 -
2-6
Test 3.2 - - - - - - - - - - - - - 0.001 0.0011 0.0013 0.0013 -
2-7
Test 3.2 - - - - - - - - - - - - - 0.001 0.0010 0.0009 0.0011 -
2-8
Test 3.2 - - - - - - - - - - - - - 0.001 0.0011 0.0010 0.0014 -
2-9
Test 3.2 - - - - - - - - - - - - - 0.001 0.0010 0.0009 0.0013 -
2-10
Test 3.2 - - - - - - - - - - - - - 0.001 0.0012 0.0010 0.0012 -
2-11
Test 3.2 - - - - - - - - - - - - - 0.001 0.0012 0.0010 0.0014 -
2-12
Test 3.2 - - - - - - - - - - - - - 0.001 0.0013 0.0011 0.0013 -
80
1 r~~! 13·2 1 - 1-1 - 1 - 1 - 1 - 1 - 1 - 1 - 1 - 1 - 1 - 1 - 1 0.001 1 0.00121 0.0012
1
0.0014
1
- I
[0197]
[Table 15]
Production results
Component composition of silicon steel sheet (unit: mass%, remainder being Fe and impurities)
Si Mn Cr Cu p Sn Sb Ni B v Nb Mo Ti Bi Al c N s Se
Test 3.2 - - - - - - - - - - - - - 0.001 0.0013 0.0008 0.0008 -
2-15
Test 3.2 - - - - - - - - - - - - - 0.001 0.0012 0.0011 0.0012 -
2-16
Test 3.2 - - - - - - - - - - - - - 0.001 0.0012 0.0012 0.0013 -
2-17
Test 3.2 - - - - - - - - - - - - - 0.001 0.0011 0.0013 0.0012 -
2-18
Test 3.2 - - - - - - - - - - - - - 0.001 0.0011 0.0012 0.0012 -
2-19
Test 3.2 - - - - - - - - - - - - - 0.001 0.0012 0.0011 0.0011 -
2-20
Test 3.2 - - - - - - - - - - - - - 0.001 0.0010 0.0012 0.0013 -
2-21
Test 3.2 - - - - - - - - - - - - - 0.001 0.0006 0.0012 0.0012 -
2-22
Test 3.2 - - - - - - - - - - - - - 0.001 0.0012 0.0011 0.0013 -
2-23
Test 3.3 0.1 - - - - - - - - - - - - 0.001 0.0007 0.0006 0.0013 -
2-24
81
Test 3.3 - 0.1 - - - - - - - - - - - 0.001 0.0009 0.0013 0.0008 0.0015
2-25
Test 3.3 - - 0.1 - - - - - - - - - - 0.001 0.0011 0.0010 0.0012 -
2-26
Test 3.3 - - - 0.01 - - - - - - - - - 0.001 0.0007 0.0006 0.0014 -
2-27
Test 3.3 - - - - 0.05 - - - - - - - - 0.001 0.0009 0.0011 0.0008 0.0016
2-28
[0198]
[Table 16]
Production results
Component composition of silicon steel sheet (unit: mass%, remainder being Fe and impurities)
Si Mn Cr Cu p Sn Sb Ni B v Nb Mo Ti Bi Al c N s Se
Test 3.3 - - - - - 0.03 - - - - - - - 0.001 0.0009 0.0010 0.0013 -
2-
29
Test 3.3 - - - - - - 0.05 - - - - - - 0.001 0.0013 0.0010 0.0009 0.0014
2-
30
Test 3.3 - - - - - - - 0.002 - - - - - 0.001 0.0013 0.0011 0.0008 0.0015
2-
31
Test 3.3 - - - - - - - - 0.02 - - - - 0.002 0.0014 0.0009 0.0014 -
2-
32
Test 3.3 - - - - - - - - - 0.03 - - - 0.001 0.0013 0.0010 0.0013 -
2-
33
82
Test 3.3 - - - - - - - - - - 0.02 - - 0.001 0.0007 0.0006 0.0012 -
2-
34
Test 3.3 - - - - - - - - - - - 0.005 - 0.001 0.0012 0.0011 0.0014 -
2-
35
Test 3.3 - - - - - - - - - - - - 0.003 0.001 0.0012 0.0010 0.0007 0.0017
2-
36
Test 3.2 - - - - - - - - - - - - - 0.001 0.0011 0.0011 0.0011 -
2-
37
Test 3.2 - - - - - - - - - - - - - 0.001 0.0010 0.0012 0.0012 -
2-
38
Test 3.2 - - - - - - - - - - - - - 0.001 0.0013 0.0011 0.0011 -
2-
39
Test 3.2 - - - - - - - - - - - - - 0.001 0.0008 0.0013 0.0014 -
2-
40
Test 3.2 - - - - - - - - - - - - - 0.001 0.0009 0.0014 0.0014 -
2-
41
Test 3.2 - - - - - - - - - - - - - 0.001 0.0010 0.0014 0.0014 -
2-
42
[0199]
[Table 17]
83
Production results
Component composition of silicon steel sheet (unit: mass%, remainder being Fe and impurities)
Si Mn Cr Cu p Sn Sb Ni B v Nb Mo Ti Bi Al c N s Se
Test 3.2 - - - - - - - - - - - - - 0.001 0.0011 0.0012 0.0012 -
2-43
Test 3.2 - - - - - - - - - - - - - 0.001 0.0008 0.0011 0.0013 -
2-44
Test 3.2 - - - - - - - - - - - - - 0.001 0.0012 0.0012 0.0011 -
2-45
Test 3.2 - - - - - - - - - - - - - 0.001 0.0010 0.0013 0.0014 -
2-46
Test 3.2 - - - - - - - - - - - - - 0.001 0.0011 0.0011 0.0012 -
2-47
Test 3.2 - - - - - - - - - - - - - 0.001 0.0011 0.0012 0.0011 -
2-48
Test 3.2 - - - - - - - - - - - - - 0.001 0.0010 0.0013 0.0012 -
2-49
Test 3.2 - - - - - - - - - - - - - 0.001 0.0011 0.0011 0.0010 -
2-50
Test 3.2 - - - - - - - - - - - - - 0.001 0.0011 0.0012 0.0011 -
2-51
Test 3.2 - - - - - - - - - - - - - 0.001 0.0012 0.0012 0.0012 -
2-52
Test 3.2 - - - - - - - - - - - - - 0.001 0.0011 0.0013 0.0013 -
2-53
Test 3.2 - - - - - - - - - - - - - 0.001 0.0008 0.0008 0.0008 -
2-54
Test 3.2 - - - - - - - - - - - - - 0.001 0.0008 0.0009 0.0007 -
2-55
[0200]
84
[Table 18]
Production results Evaluation results Note
Surface properties of silicon steel sheet Iron loss in Iron loss in
ave-AMPcwo ave-AMPcso max-DIV1oo max-DIVso J.!m rolling sheet width
Jlm Jlm Jlm direction direction W 6/50
W171so W/kg W/kg
Test 2-1 0.060 0.044 1.2 1.1 0.72 0.95 Comparative
example
Test 2-2 0.059 0.043 1.3 1.1 0.71 0.92 Comparative
example
Test 2-3 0.052 0.038 1.4 1.3 0.70 0.90 Comparative
example
Test 2-4 0.050 0.038 1.6 1.4 0.68 0.65 Example of
present
invention
Test 2-5 0.046 0.034 2.0 1.7 0.66 0.62 Example of
present
invention
Test 2-6 0.044 0.032 2.1 1.6 0.66 0.61 Example of
present
invention
Test 2-7 0.027 0.019 2.5 2.1 0.65 0.58 Example of
present
invention
Test 2-8 0.044 0.032 1.2 1.1 0.65 0.86 Example of
present
invention
Test 2-9 0.049 0.038 1.8 1.5 0.68 0.66 Example of
present
85
invention
Test 2-10 0.043 0.031 2.1 1.8 0.65 0.60 Example of
present
invention
Test 2-11 0.042 0.031 1.3 1.3 0.65 0.87 Example of
present
invention
Test 2-12 0.047 0.034 1.8 1.5 0.66 0.64 Example of
present
invention
Test 2-13 0.043 0.031 2.2 1.9 0.65 0.59 Example of
present
invention
Test 2-14 0.030 0.022 1.9 1.6 0.66 0.76 Example of
present
invention
[0201]
[Table 19]
Production results Evaluation results Note
Surface properties of silicon steel sheet Iron loss in Iron loss in
ave-AMPcwo ave-AMPcso max-DIV1oo max-DIVso J.!m rolling sheet width
Jlm Jlm Jlm direction direction W 6/50
W171so W/kg W/kg
Test 2-15 0.025 0.018 3.0 2.5 0.64 0.52 Example of
present
invention
Test 2-16 0.036 0.026 2.2 1.8 0.68 0.66 Example of
present
86
invention
Test 2-17 0.030 0.021 2.4 2.0 0.64 0.62 Example of
present
invention
Test 2-18 0.027 0.019 2.6 2.2 0.65 0.56 Example of
present
invention
Test 2-19 0.033 0.023 1.9 1.6 0.68 0.76 Example of
present
invention
Test 2-20 0.028 0.021 2.5 2.1 0.64 0.58 Example of
present
invention
Test 2-21 0.061 0.045 1.3 1.1 0.72 0.96 Comparative
example
Test 2-22 0.184 0.134 1.1 0.9 0.77 0.99 Comparative
example
Test 2-23 0.098 0.072 1.1 0.9 0.73 0.93 Comparative
example
Test 2-24 0.028 0.020 2.4 2.0 0.64 0.60 Example of
present
invention
Test 2-25 0.027 0.019 2.7 2.4 0.65 0.54 Example of
present
invention
Test 2-26 0.026 0.018 2.1 1.8 0.64 0.69 Example of
present
invention
Test 2-27 0.027 0.020 2.3 1.9 0.65 0.63 Example of
present
87
invention
Test 2-28 0.025 0.018 3.0 2.5 0.64 0.48 Example of
present
invention
[0202]
[Table 20]
Production results Evaluation results Note
Surface properties of silicon steel sheet Iron loss in Iron loss in
ave-AMPcwo ave-AMPcso max-DIV1oo max-DIVso J.!m rolling sheet width
Jlm Jlm Jlm direction direction W 6/50
W171so W/kg W/kg
Test 2-29 0.025 0.019 2.4 2.1 0.63 0.60 Example of
present
invention
Test 2-30 0.027 0.020 2.7 2.3 0.65 0.54 Example of
present
invention
Test 2-31 0.026 0.019 2.5 2.0 0.63 0.58 Example of
present
invention
Test 2-32 0.028 0.021 2.3 1.9 0.64 0.63 Example of
present
invention
Test 2-33 0.029 0.022 2.4 1.9 0.65 0.60 Example of
present
invention
Test 2-34 0.026 0.020 2.6 2.2 0.64 0.56 Example of
present
88
invention
Test 2-35 0.026 0.019 2.3 1.9 0.65 0.63 Example of
present
invention
Test 2-36 0.027 0.020 2.7 2.4 0.63 0.54 Example of
present
invention
Test 2-37 0.045 0.029 1.2 1.1 0.66 0.87 Example of
present
invention
Test 2-38 0.048 0.037 1.4 1.3 0.68 0.83 Example of
present
invention
Test 2-39 0.067 0.049 1.4 1.3 0.72 0.81 Comparative
example
Test 2-40 0.180 0.131 1.1 0.9 0.79 0.93 Comparative
example
Test 2-41 0.053 0.040 1.4 1.3 0.71 0.83 Comparative
example
Test 2-42 0.056 0.042 1.4 1.3 0.73 0.81 Comparative
example
[0203]
[Table 21]
Production results Evaluation results Note
Surface properties of silicon steel sheet Iron loss in Iron loss in
ave-AMPcwo ave-AMPcso max-DIV1oo max-DIVso J.!m rolling sheet width
Jlm Jlm Jlm direction direction W 6/50
W171so W/kg W/kg
89
Test 2-43 0.122 0.038 1.3 1.0 0.84 0.86 Comparative
example
Test 2-44 0.093 0.068 1.3 1.1 0.74 0.85 Comparative
example
Test 2-45 0.090 0.066 1.4 1.3 0.73 0.82 Comparative
example
Test 2-46 0.049 0.039 1.4 1.2 0.68 0.81 Example of
present
invention
Test 2-47 0.071 0.062 2.1 1.8 0.75 0.70 Comparative
example
Test 2-48 0.046 0.034 1.3 1.2 0.68 0.83 Example of
present
invention
Test 2-49 0.044 0.030 1.4 1.3 0.66 0.81 Example of
present
invention
Test 2-50 0.068 0.059 2.2 1.7 0.73 0.71 Comparative
example
Test 2-51 0.044 0.035 1.3 1.3 0.66 0.84 Example of
present
invention
Test 2-52 0.055 0.041 1.7 1.5 0.70 0.69 Comparative
example
Test 2-53 0.049 0.036 2.1 1.8 0.68 0.70 Example of
present
invention
Test 2-54 0.019 0.013 2.5 2.1 0.60 0.67 Example of
present
invention
90
00
\0
0
[Industrial Applicability]
[0204]
According to the above aspects of the present invention, when surface properties
of the silicon steel sheet as a base are optimally controlled, it is possible to provide a
5 grain-oriented electrical steel sheet that exhibits excellent iron loss characteristics and a
method of producing the same. Therefore, the present invention has high industrial
applicability.

WE CLAIMS

1. A grain -oriented electrical steel sheet including a silicon steel sheet as a base steel
sheet,
wherein, when an average value of amplitudes in a wavelength range of 20 to
100 ~m among wavelength components obtained by performing Fourier analysis on a
measured cross-sectional curve parallel to a sheet width direction of the silicon steel
sheet is set as ave-AMPc10o, ave-AMPc10o is 0.0001 to 0.050 ~m.
10 2. The grain-oriented electrical steel sheet according to claim 1,
wherein ave-AMPc10o is 0.0001 to 0.025 ~m.
3. The grain-oriented electrical steel sheet according to claim 1 or 2,
wherein, when a maximum value of amplitudes in a wavelength range of 20 to
15 100 ~m among wavelength components obtained by performing Fourier analysis on the
measured cross-sectional curve parallel to the sheet width direction of the silicon steel
sheet is set as max-AMPc10o and a maximum value of amplitudes in a wavelength range
of 20 to 100 ~m among wavelength components obtained by performing Fourier analysis
on a measured cross-sectional curve parallel to the rolling direction of the silicon steel
20 sheet is set as max-AMPuoo, max-DIV 100, which is a value obtained by dividing maxAMPclOo
by max-AMPuoo, is 1.5 to 6.0.
4. The grain-oriented electrical steel sheet according to any one of claims 1 to 3,
wherein, when an average value of amplitudes in a wavelength range of 20 to 50
25 ~m among the wavelength components obtained by performing Fourier analysis is set as
93
ave-AMPcso, ave-AMPcso is 0.0001 to 0.035.
5. The grain-oriented electrical steel sheet according to claim 4,
wherein, when a maximum value of amplitudes in a wavelength range of 20 to
5 50 ~m among wavelength components obtained by performing Fourier analysis on the
measured cross-sectional curve parallel to the sheet width direction of the silicon steel
sheet is set as max-AMPcso and a maximum value of amplitudes in a wavelength range
of 20 to 50 ~m among wavelength components obtained by performing Fourier analysis
on the measured cross-sectional curve parallel to the rolling direction of the silicon steel
10 sheet is set as max-AMPLso, max-DIVso, which is a value obtained by dividing maxAMPcso
by max-AMPLso, is 1.5 to 5.0.
15
20
25
6. The grain-oriented electrical steel sheet according to claim 4 or 5,
wherein ave-AMPcso is 0.0001 to 0.020 ~m.
7. The grain-oriented electrical steel sheet according to any one of claims 1 to 6,
wherein the silicon steel sheet contains, as chemical components, by mass%,
Si: 0.8% or more and 7.0% or less,
Mn: 0 or more and 1.00% or less,
Cr: 0 or more and 0.30% or less,
Cu: 0 or more and 0.40% or less,
P : 0 or more and 0.50% or less,
Sn: 0 or more and 0.30% or less,
Sb: 0 or more and 0.30% or less,
Ni: 0 or more and 1.00% or less,
94
5
10
B: 0 or more and 0.008% or less,
V : 0 or more and 0.15% or less,
Nb: 0 or more and 0.2% or less,
Mo: 0 or more and 0.10% or less,
Ti: 0 or more and 0.015% or less,
Bi: 0 or more and 0.010% or less,
Al: 0 or more and 0.005% or less,
C : 0 or more and 0.005% or less,
N : 0 or more and 0.005% or less,
S : 0 or more and 0.005% or less, and
Se: 0 or more and 0.005% or less,
with the remainder being Fe and impurities.
8. The grain-oriented electrical steel sheet according to any one of claims 1 to 7,
15 wherein the silicon steel sheet has a texture developed in the { 110 }<001>
20
25
orientation.
9. The grain-oriented electrical steel sheet according to any one of claims 1 to 8, further
compns1ng
an intermediate layer arranged in contact with the silicon steel sheet,
wherein the intermediate layer is a silicon oxide film.
10. The grain-oriented electrical steel sheet according to claim 9, further comprising
an insulation coating arranged in contact with the intermediate layer,
wherein the insulation coating is a phosphoric acid-based coating.
95
5
11. The grain -oriented electrical steel sheet according to claim 9, further comprising
an insulation coating arranged in contact with the intermediate layer,
wherein the insulation coating is an aluminum borate-based coating.
12. A method of producing the grain-oriented electrical steel sheet according to any one
of claims 1 to 11, comprising
producing a grain-oriented electrical steel sheet using the silicon steel sheet as a
base.