FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(See section 10 and rule 13)
1. Title of the Invention
GRAIN-ORIENTED ELECTRICAL STEEL SHEET AND MANUFACTURING METHOD
THEREFOR
2. Applicant(s)
Name Nationality Address
POSCO Korean (Goedong-dong) 6261 Donghaean-ro,
Nam-gu, Pohang-si Gyeongsangbuk-do
37859, Republic of Korea
3. Preamble to the description
The following specification particularly describes the invention and the manner in which it is to be
performed.
2
【DESCRIPTION】
【Technical Field】
The present invention relates to an oriented electrical steel sheet
and a manufacturing method thereof.
5 【Background Art】
Generally, in an oriented electrical steel sheet having an excellent
magnetic characteristic, a Goss texture of a {110}<001> orientation should
strongly develop in a rolling direction thereof, and in order to form such a
Goss texture, abnormal grain growth corresponding to secondary
10 recrystallization must be formed. The abnormal grain growth occurs
when normal grain growth is inhibited by precipitates, inclusions, or
elements that are solidified or segregated, unlike the normal grain growth.
The oriented electrical steel sheet is mainly manufactured by a
manufacturing method in which a precipitate such as AlN, MnS, or the like
15 is used as a grain growth inhibitor to cause secondary recrystallization.
The method of manufacturing the oriented electrical steel sheet by using
the precipitate such as AlN, MnS, or the like as the grain growth inhibitor
has the following problems. In order to use the AlN and MnS precipitates
as the grain growth inhibitor, the precipitates should be distributed very
20 finely and uniformly on the steel sheet. In order to uniformly distribute the
fine precipitates to the steel sheet, a slab should be heated at a high
temperature of 1300 °C or higher for a long time to solidify coarse
precipitates present in steel, and then a hot-rolling process should be
3
performed and finished in a very short time in a state in which no
precipitation occurs. For this, a large slab heating system is required,
and in order to suppress the precipitation as much as possible, the hotrolling
process and a winding process should be managed very strictly and
the precipitates solidified in a hot-rolled steel 5 sheet annealing process
after the hot-rolling process should be controlled to be finely precipitated.
In addition, when the slab is heated at a high temperature, since a slab
washing phenomenon occurs due to formation of Fe2SiO4 having a low
melting point, an actual yield is lowered. Further, a purification annealing
10 process must be performed for a long time at a high temperature of
1200 °C for 30 hours or more in order to remove precipitate components
after the completion of the secondary recrystallization, which complicates
a manufacturing process and causes a cost burden. Further, in the
purification annealing process, after AlN-based precipitates are
15 decomposed into Al and N, Al moves to a surface of the steel sheet and
reacts with oxygen in a surface oxide layer to form Al2O3 oxide. The
formed Al-based oxide and the AlN precipitates not decomposed in the
purification annealing process interfere with movement of a magnetic
domain in the steel sheet or near the surface, thereby deteriorating iron
20 loss.
【DISCLOSURE】
【Technical Problem】
The present invention has been made in an effort to provide an
4
oriented electrical steel sheet.
The present invention has also been made in an effort to provide a
manufacturing method of the oriented electrical steel sheet.
【Technical Solution】
An exemplary embodiment of the 5 present invention provides an
oriented electrical steel sheet including Ba alone at about 0.005 wt% to
about 0.5 wt%, Y alone at about 0.005 wt% to about 0.5 wt%, or a
composite of Ba and Y at about 0.005 wt% to about 0.5 wt%, the
remainder including Fe and impurities, based on 100 wt% of a total
10 composition of a base steel sheet thereof.
The base steel sheet thereof may include Si at about 1.0 wt% to
about 7.0 wt%, C at about 0.0050 wt% or less (excluding 0 wt%), Al at
about 0.005 wt% or less (excluding 0 wt%), N at about 0.0055 wt% or less
(excluding 0 wt%), S at about 0.0055 wt% or less (excluding 0 wt%), and
15 Mn at about 0.01 wt% to about 0.5 wt%.
An area of grains of the electrical steel sheet having a grain size of
about 2 mm or less may be about 10 % or less with respect to 100 % of an
area of total grains.
An average size of grains of the electrical steel sheet having a
20 grain size of about 2 mm or more may be about 10 mm or more.
An angle difference between a <100> plane and a plate plane of
the electrical steel sheet may be about 3.5° or less.
B10 corresponding to magnetic flux density of the electrical steel
5
sheet measured at a magnetic field of about 1000 A/m may be about 1.88
or more.
The electrical steel sheet may include Ba, Y, or a combination
thereof that is segregated at grain boundaries.
Another embodiment of the 5 present invention provides A
manufacturing method of an oriented electrical steel sheet, including:
heating a slab including Ba alone at about 0.005 wt% to about 0.5 wt%, Y
alone at about 0.005 wt% to about 0.5 wt%, or a composite of Ba and Y at
about 0.005 wt% to about 0.5 wt%, and the remaining portion including Fe
10 and other inevitably incorporated impurities, based on 100 wt% of a total
composition of the slab; producing a hot-rolled steel sheet by hot-rolling
the slab; producing a cold-rolled steel sheet by cold-rolling the hot-rolled
steel sheet; performing primary recrystallization annealing for the coldrolled
steel sheet; and performing secondary recrystallization annealing for
15 an electrical steel sheet for which the primary recrystallization annealing is
completed.
The slab may include Si at about 1.0 wt% to about 4.5 wt%, C at
about 0.001 wt% to about 0.1 wt%, Al at about 0.005 wt% or less, N at
about 0.0055 wt% or less, S at about 0.0055 wt% or less, and Mn at about
20 0.01 wt% to about 0.5 wt%.
A slab heating temperature in the heating of the slab may be about
1280 °C or lower.
A soaking temperature in the secondary recrystallization annealing
6
may be about 900 °C to about 1250 °C.
After the hot-rolling, hot-rolled steel sheet annealing may be
performed.
In the primary recrystallization annealing, the cold-rolled steel
sheet may be maintained at a temperature of 750 5 °C or higher for about
30 seconds or more.
【Advantageous Effects】
The oriented electrical steel sheet according to the embodiment of
the present invention has low iron loss and excellent magnetic
10 characteristics by stably forming Goss grains.
In addition, since AlN and MnS are not used as the grain growth
inhibitor, it is unnecessary to reheat the slab at a temperature higher than
1300 °C.
Further, since high temperature purification annealing for removing
15 precipitates such as AlN and MnS is not required, manufacturing cost is
reduced.
Further, since there is no need to remove N, S, or the like after the
high temperature annealing process, there is no surface defect due to a
gasification reaction with N and S in the high temperature purification
20 annealing process.
【Mode for Invention】
The advantages and features of the present invention and the
methods for accomplishing the same will be apparent from the exemplary
7
embodiments described hereinafter with reference to the accompanying
drawings. However, the present invention is not limited to the exemplary
embodiments described hereinafter, but may be embodied in many
different forms. The following exemplary embodiments are provided to
make the disclosure of the present invention complete 5 and to allow those
skilled in the art to clearly understand the scope of the present invention,
and the present invention is defined only by the scope of the appended
claims. Throughout the specification, the same reference numerals
denote the same constituent elements.
10 In some exemplary embodiments, detailed description of wellknown
technologies will be omitted to prevent the disclosure of the present
invention from being interpreted ambiguously. Unless otherwise defined,
all terms (including technical and scientific terms) used herein have the
same meaning as commonly understood by one of ordinary skill in the art.
15 In addition, throughout the specification, unless explicitly described to the
contrary, the word "comprise" and variations such as "comprises" or
"comprising" will be understood to imply the inclusion of stated elements
but not the exclusion of any other elements. Further, as used herein, the
singular forms "a", "an", and "the" are intended to include the plural forms
20 as well, unless the context clearly indicates otherwise.
Further, as used herein, % means wt%, and 1 ppm corresponds to
0.0001 wt%, unless the context clearly indicates otherwise.
Hereinafter, a manufacturing method of an oriented electrical steel
8
sheet according to an exemplary embodiment of the present invention will
be described.
A slab that includes Ba alone at about 0.005 wt% to about 0.5 wt%,
Y alone at about 0.005 wt% to about 0.5 wt%, or a composite of Ba and Y
at about 0.005 wt% to about 0.5 wt%, and 5 the remaining portion including
Fe and other inevitably incorporated impurities, is provided.
The slab may include Si at about 1.0 wt% to about 4.5 wt%, C at
less than about 0.005 wt%, Al at less than about 0.005 wt%, N at less than
about 0.0055 wt%, S at less than about 0.0055 wt%, and Mn at about 0.01
10 wt% to about 0.5 wt%.
First, reasons for limiting components will be described.
Ba and Y serve as grain growth inhibitors to prevent grains of
orientations other than Goss grains from growing during secondary
recrystallization annealing, thereby improving magnetism of an electrical
15 steel sheet. Ba and Y may be added singly or in combination. When a
content of Ba or Y is less than about 0.005 wt%, it is difficult to sufficiently
serve as the inhibitor, and when the content thereof is more than about 0.5
wt%, brittleness of the steel sheet increases, thus cracks may occur during
rolling.
20 Si serves to reduce iron loss by increasing specific resistance of a
material. When the content of Si is less than about 1.0 wt% in the slab
and the electrical steel sheet, the specific resistance thereof may decrease
and the iron loss thereof may deteriorate. In addition, when the content
9
of Si of the slab exceeds about 4.5 wt%, it may be difficult to perform coldrolling.
However, after the cold-rolling, since Si powder may be coated or
deposited on a surface of the steel sheet and then Si may be diffused into
the steel sheet, a content of Si of a final steel sheet may be about 4.5 wt%
or more. However, when the Si content of the 5 oriented electrical steel
sheet exceeds about 7 wt%, since it is difficult to process the oriented
electrical steel sheet for manufacturing a transformer, the Si content
thereof may about 7 wt% or less.
C is an austenite stabilizing element added to the slab in an
10 amount of about 0.001 wt% or more such that a coarse columnar structure
occurring during a continuous casting process may be miniaturized and
slab center segregation of S may be suppressed. In addition, it is
possible to promote work hardening of the steel sheet during cold-rolling
and to promote nucleation of secondary recrystallization of a {110}<001>
15 orientation in the steel sheet. However, when C exceeds about 0.1 wt%,
an edge crack may occur during hot-rolling. Therefore, while the
electrical steel sheet is manufactured, a decarburization annealing
process is performed, and a C content after the decarburization annealing
process may be about 0.0050 wt% or less. Specifically, C may be about
20 0.0030 wt% or less.
In the exemplary embodiment of the present invention, since AlN
may not be used as a grain growth inhibitor, a content of Al may be
positively suppressed. Accordingly, in the exemplary embodiment of the
10
present invention, Al may be added or controlled to about 0.005 wt%.
Since N forms precipitates such as AlN, (Al, Mn)N, (Al, Si, Mn)N,
Si3N4, and the like, N may not be added or may be controlled to about
0.0055 wt% or less in the exemplary embodiment of the present invention.
Specifically, N may be present at about 5 0.0035 wt% or less. More
specifically, N may be present at about 0.0015 wt% or less.
S is an element having a high solid solution temperature and a
high segregation temperature during hot-rolling, thus it may not be added
or may be controlled to 0.0055 % or less in the exemplary embodiment of
10 the present invention. Specifically, S may be present at about 0.0035
wt%. More specifically, S may be present at about 0.0015 wt%.
In the exemplary embodiment of the present invention, since MnS
may not be used as a grain growth inhibitor, Mn may not be added.
However, since Mn is a specific resistance element and improves
15 magnetism, a content of Mn of the slab and of the electrical steel sheet
may be about 0.01 wt% or more. However, when Mn exceeds about 0.5
wt%, a phase thereof may be transformed after the secondary
recrystallization, thus the magnetism may deteriorate.
Components such as Ti, Mg, Ca, etc. are preferably not added
20 because they react with oxygen in the steel to form oxides. However,
they may be controlled to about 0.005 wt% or less in consideration of
impurities of the steel.
The slab is heated. A temperature of heating the slab is not
11
limited, but when the slab is heated at a temperature of about 1280 °C or
lower, it is possible to prevent the columnar structure of the slab from
being coarsely grown, thereby preventing cracking of the slab in the hotrolling
process. Therefore, the temperature of heating the slab may be
about 1000 °C or more and 5 about 1280 °C or less.
When the reheating of the slab is completed, hot-rolling is
performed. A temperature of the hot-rolling and a cooling temperature
are not particularly limited, and for example, the hot-rolling may be
terminated at about 950 °C or less, followed by water cooling, and then
10 spiral-winding at about 600 °C.
The hot-rolled steel sheet may be annealed as necessary, or may
be cold-rolled without annealing. In the case of annealing the hot-rolled
steel sheet, the hot-rolled steel sheet may be heated at a temperature of
about 900 °C or higher, soaked, and then cooled so that a hot-rolled
15 structure is made uniform.
The cold-rolling is performed by a reverse mill or a tandem mill,
and a cold-rolled steel sheet having a thickness of about 0.1 mm to about
0.5 mm may be manufactured by one cold-rolling process, a plurality of
cold-rolling processes, or a plurality of cold-rolling processes including an
20 intermediate annealing process.
Warm-rolling in which a temperature of the steel sheet is
maintained at about 100 °C or higher during the cold-rolling may be
performed. In addition, a cold-rolled steel sheet having a final thickness
12
of about 0.1 mm to about 0.5 mm may be manufactured through coldrolling
once.
The cold-rolled steel sheet is subjected to primary recrystallization
annealing. In the primary recrystallization annealing, primary
recrystallization occurs in which decarburization 5 is performed and nuclei of
Goss grains are generated.
In the primary recrystallization annealing, the cold-rolled sheet may
be maintained at a temperature of about 750 °C or higher for about 30
seconds or more. If the temperature is less than about 750 °C, sufficient
10 energy for grain growth may not be provided, and if the energy is provided
for less than 30 seconds, the grain growth may be insufficient, thus
magnetism may deteriorate.
In addition, in the manufacturing method of the oriented electrical
steel sheet according to the exemplary embodiment of the present
15 invention, after the decarburization annealing process is performed, a
nitride annealing process may be omitted. In a conventional
manufacturing method of an oriented electrical steel sheet using AlN as a
grain growth inhibitor, a nitride annealing process is required for the
formation of AlN. However, in the manufacturing method of the oriented
20 electrical steel sheet according to the embodiment of the present invention,
since AlN is not used as a grain growth inhibitor, the nitride annealing
process is not required.
After completion of the primary recrystallization annealing, the
13
steel sheet is coated with an annealing separator containing MgO, and is
subjected to secondary recrystallization annealing. A soaking
temperature during the secondary recrystallization annealing may be
about 900 °C to about 1250 °C. If the soaking temperature is less than
about 900 °C, Goss grains may not sufficiently grow 5 and magnetism may
deteriorate, while if the soaking temperature exceeds about 1250 °C, the
grains may coarsely grow such that characteristics of the steel sheet may
deteriorate.
In the manufacturing method of the oriented electrical steel sheet
10 according to the embodiment of the present invention, after the secondary
recrystallization annealing is completed, purification annealing may be
omitted.
In a conventional manufacturing method of an oriented electrical
steel sheet using MnS and AlN as a grain growth inhibitor, it is necessary
15 to perform a high-temperature purification annealing process to remove
precipitates such as AlN and MnS, but in the manufacturing method of the
oriented electrical steel sheet according to the embodiment of the present
invention, a purification annealing process may not be necessary.
A base steel sheet of the oriented electrical steel sheet according
20 to the embodiment of the present invention may include about 0.005 wt%
to about 0.5 wt% of Ba alone, about 0.005 wt% to about 0.5 wt% of Y
alone, or about 0.005 wt% to about 0.5 wt% of a composite of Ba and Y,
the remainder including Fe and impurities. In this case, the base steel
14
sheet corresponds to a portion excluding a coated layer formed on a
surface of the oriented electrical steel sheet.
In addition, the base steel sheet may include about 1.0 wt% to
about 7.0 wt% of Si, about 0.005 wt% or less of C, about 0.005 wt% or
less of Al, about 0.0055 wt% or less of N, about 5 0.0055 wt% or less of S,
and about 0.01 wt% to about 0.5 wt% of Mn.
Further, the base steel sheet may include about 0.02 wt% to about
0.35 wt% of Ba, Y, or a combination thereof.
In the oriented electrical steel sheet, an area of grains having a
10 grain size of about 2 mm or less may be about 10 % or less of a total area
of grains of 100 %. When the area of the grains having the grain size of
about 2 mm or less is more than about 10 % of the whole area of the
grains of 100 %, the grains may not sufficiently grow, thus magnetism may
deteriorate.
15 In addition, in the electrical steel sheet, an average grain size of
the grains having the grain size of about 2 mm or more may be about 10
mm or more. When the average grain size of the grains having the grain
size of about 2 mm or more is less than about 10 mm, the grains may not
sufficiently grow, thus the magnetism may deteriorate.
20 In addition, in the electrical steel sheet, an angle difference between a
<100> plane and a plate plane of the steel sheet may be about 3.5° or less.
In this case, the plate plane of the steel sheet means an XY plane of the
steel sheet when a rolling direction thereof is an X axis and a width
15
direction thereof is a Y axis. When the angle difference exceeds about
3.5°, the magnetism of the steel sheet may deteriorate.
In addition, in the steel sheet, B10, magnetic flux density measured
at a magnetic field of about 1000 A/m may be about 1.88 or more.
Further, Ba, Y, or a combination thereof 5 may be segregated at grain
boundaries by serving as inhibitors.
Hereinafter, exemplary embodiments will be described. However,
the following exemplary embodiments are only examples of the present
invention, and the present invention is not limited to the exemplary
10 embodiments.
[Exemplary Embodiment 1]
A slab including with Si at 3.2 wt%, C at 0.051 wt%, Mn at 0.112
wt%, S at 0.0052 wt%, N at 0.005 wt%, Al at 0.029 wt%, barium (Ba) and
yttrium (Y) as shown in Table 1, and the remaining portion including Fe
15 and other inevitably incorporated impurities, was prepared.
The slab was heated at a temperature of 1150 °C for 90 minutes,
and then hot-rolled to prepare a hot-rolled steel sheet having a thickness
of 2.6 mm. The hot-rolled steel sheet was heated at a temperature of
1050 °C or higher, maintained at 910 °C for 90 seconds, water-cooled,
20 and then pickled. Then, it was cold-rolled to a thickness of 0.29 mm.
The cold-rolled steel sheet was heated in a furnace, maintained in a mixed
gas atmosphere of hydrogen at 50 vol% and nitrogen at 50 vol%, a dew
point temperature of 60 °C, and an annealing temperature of 850 °C for
16
120 seconds, and then subjected to primary recrystallization annealing.
After the primary recrystallization annealing, an amount of carbon was
0.0030 wt%. Then, it was coated with MgO, wound in a coil form, and
then subjected to secondary recrystallization annealing.
In final annealing, it was heated to 5 1200 °C in a mixed gas
atmosphere of nitrogen at 25 vol% and hydrogen at 75 vol%, and after
reaching 1200 °C, it was maintained in a gas atmosphere of hydrogen at
100 vol% for 20 hours, and then cooled.
(Table 1)
Sample
number
Ba
content
Y
Content
Magnetic flux
density (B10,
Tesla)
Classification
A 0 0 1.52
Comparative
material
B 0.06 0 1.9
Inventive
material
C 0.12 0 1.92
Inventive
material
D 0.18 0 1.9
Inventive
material
E 0.6 0
Rolling crack
occurrence
Comparative
material
F 0 0.12 1.9 Inventive
17
material
G 0 0.2 1.93
Inventive
material
H 0 0.3 1.9
Inventive
material
I 0 0.7
Rolling crack
occurrence
Comparative
material
J 0.002 0.002 1.52
Comparative
material
K 0.08 0.03 1.94
Inventive
material
L 0.6 0.03 1.61
Comparative
material
M 0.04 0.46 1.91
Inventive
material
N 0.12 0.38 1.91
Inventive
material
O 0.1 0.6 1.56
Comparative
material
As shown in Table 1, the magnetism of the inventive material in
which contents of Ba and Y are controlled in a range of 0.005 % to 0.5 %
as a range of the present invention is superior to that of the comparative
18
material.
[Exemplary Embodiment 2]
A slab including Si at 3.2 wt%, C at 0.051 wt%, Mn at 0.112 wt%, S
at 0.0052 wt%, N at 0.005 wt%, Al at 0.029 wt%, barium (Ba) and yttrium
(Y) as shown in Table 2, and the remaining portion 5 including Fe and other
inevitably incorporated impurities, was prepared.
The slab was heated at a temperature of 1150 °C for 90 minutes,
and then hot-rolled to prepare a hot-rolled steel sheet having a thickness
of 2.6 mm. The hot-rolled steel sheet was heated at a temperature of
10 1050 °C or higher, maintained at 910 °C for 90 seconds, water-cooled,
and then pickled. Then, it was cold-rolled to a thickness of 0.29 mm.
The cold-rolled steel sheet was heated in a furnace, maintained in a mixed
gas atmosphere of hydrogen at 50 vol% and nitrogen at 50 vol%, a dew
point temperature of 60 °C, and an annealing temperature of 850 °C for
15 120 seconds, and then subjected to primary recrystallization annealing.
After the primary recrystallization annealing, an amount of carbon was
0.0030 wt%. Then, it was coated with MgO, wound in a coil form, and
then subjected to secondary recrystallization annealing.
In final annealing, it was heated to 1200 °C in a mixed gas
20 atmosphere of nitrogen at 25 vol% and hydrogen at 75 vol%, and after
reaching 1200 °C, it was maintained in a gas atmosphere of hydrogen at
100 vol% for 20 hours, and then cooled.
(Table 2)
19
Ba
content
(wt%)
Y
content
(wt%)
Area ratio of
grains of 1 mm
or less
(%)
Average size of
grains of 1 mm or
more
(mm)
Magnetic
flux density
(B10,
Tesla)
0 0 100 - 1.53
0.08 0.03 2 25 1.92
As shown in Table 2, in the electrical steel sheet according to the
embodiment of the present invention, the area of the grains having the
size of 1 mm or less was 10 % or less, and the average size of the grains
having the size of 1 mm 5 or more was 10 mm or more.
While the exemplary embodiments of the present invention have
been described hereinbefore with reference to the accompanying
drawings, it will be understood by those skilled in the art that various
changes in form and details may be made thereto without departing from
10 the technical spirit and essential features of the present invention.
Therefore, the embodiments described above are only examples and
should not be construed as being limitative in any respects. The scope of
the present invention is determined not by the above description, but by
the following claims, and all changes or modifications from the spirit,
15 scope, and equivalents of claims should be construed as being included in
the scope of the present invention.
20
WE CLAIM:
【Claim 1】
An oriented electrical steel sheet comprising
Ba alone at about 0.005 wt% to about 0.5 wt%, Y alone at about
0.005 wt% to about 0.5 wt%, or a composite of Ba 5 and Y at about 0.005
wt% to about 0.5 wt%, the remainder including Fe and impurities, based
on 100 wt% of a total composition of a base steel sheet thereof.
【Claim 2】
10 The oriented electrical steel sheet of claim 1, wherein
the base steel sheet thereof includes Si at about 1.0 wt% to about
7.0 wt%, C at about 0.0050 wt% or less (excluding 0 wt%), Al at about
0.005 wt% or less (excluding 0 wt%), N at about 0.0055 wt% or less
(excluding 0 wt%), S at about 0.0055 wt% or less (excluding 0 wt%), and
15 Mn at about 0.01 wt% to about 0.5 wt%.
【Claim 3】
The oriented electrical steel sheet of claim 2, wherein
an area of grains of the electrical steel sheet having a grain size of
20 about 2 mm or less is about 10 % or less with respect to 100 % of an area
of total grains.
21
【Claim 4】
The oriented electrical steel sheet of claim 3, wherein
an average size of grains of the electrical steel sheet having a
grain size of about 2 mm or more is about 10 mm or more.
5
【Claim 5】
The oriented electrical steel sheet of claim 4, wherein
an angle difference between a <100> plane and a plate plane of
the electrical steel sheet is about 3.5° or less.
10
【Claim 6】
The oriented electrical steel sheet of claim 5, wherein
B10 corresponding to magnetic flux density of the electrical steel
sheet measured at a magnetic field of about 1000 A/m is about 1.88 or
15 more.
【Claim 7】
The oriented electrical steel sheet of claim 1, wherein
Ba, Y, or a combination thereof is segregated at grain boundaries
20 of the electrical steel sheet.
22
【Claim 8】
A manufacturing method of an oriented electrical steel sheet,
comprising
heating a slab including Ba alone at about 0.005 wt% to about 0.5
wt%, Y alone at about 0.005 wt% to about 0.5 wt%, 5 or a composite of Ba
and Y at about 0.005 wt% to about 0.5 wt%, the remaining portion
including Fe and other inevitably incorporated impurities, based on 100
wt% of a total composition of the slab;
producing a hot-rolled steel sheet by hot-rolling the slab;
10 producing a cold-rolled steel sheet by cold-rolling the hot-rolled
steel sheet;
performing primary recrystallization annealing for the cold-rolled
steel sheet; and
performing secondary recrystallization annealing for an electrical
15 steel sheet for which the primary recrystallization annealing is completed.
【Claim 9】
The manufacturing method of the oriented electrical steel sheet of
claim 8, wherein
20 the slab includes Si at about 1.0 wt% to about 4.5 wt%, C at about
0.001 wt% to about 0.1 wt%, Al at about 0.005 wt% or less, N at about
0.0055 wt% or less, S at about 0.0055 wt% or less, and Mn at about 0.01
wt% to about 0.5 wt%.
23
【Claim 10】
The manufacturing method of the oriented electrical steel sheet of
5 claim 8, wherein
a slab heating temperature in the heating of the slab is about
1280 °C or lower.
【Claim 11】
10 The manufacturing method of the oriented electrical steel sheet of
claim 10, wherein
a soaking temperature in the secondary recrystallization annealing
is about 900 °C to about 1250 °C.
15 【Claim 12】
The manufacturing method of the oriented electrical steel sheet of
claim 11, wherein
after the hot-rolling, hot-rolled steel sheet annealing is performed.
20 【Claim 13】
The manufacturing method of the oriented electrical steel sheet of
claim 12, wherein
in the primary recrystallization annealing, the cold-rolled steel
24
sheet is maintained at a temperature of 750 °C or higher for about 30
seconds or more.