[Technical Field of the Invention]
[0001]
The present invention relates to a non-oriented electrical steel sheet, a core, a
cold-rolled steel sheet, a method for manufacturing a non-oriented electrical steel sheet,
and a method for manufacturing a cold-rolled steel sheet.
Priority is claimed on Japanese Patent Application No. 2020-070883, filed on
April 10, 2020, the content of which is incorporated herein by reference.
[Related Art]
[0002]
Electrical steel sheets are used as a material for cores of an electric device.
Examples of the electric device include a drive motor mounted in a vehicle or a motor
for various compressors represented by an air conditioner or a refrigerator, and a power
generator for household or industrial use. These electric devices require to have high
energy efficiency, small size, and high output. Therefore, the electrical steel sheets
used as a core of the electric device require to have low iron loss and high magnetic
flux density. As a solution to obtain low iron loss and high magnetic flux density,
texture control is used, and so far, a technology for developing a structure (a-fiber) that
has an easy magnetization axis in a surface of the steel sheet, is advantageous for
improving magnetic characteristics, and can relatively easily enhance accumulation by
rolling in hot rolling and cold rolling, which are essential steps of manufacturing the
- 1 -
steel sheet, has been proposed. Specifically, a structure whose <110> direction is
substantially parallel to a rolling direction (RD) is formed.
[0003]
Patent Documents 1 to 3 all disclose a method for developing a { 100}<011>
orientation, in which a structure is refined by lowering a transformation temperature
and rapidly cooling the structure after hot rolling.
[0004]
Specifically, Patent Document 1 discloses that cooling to 250oc or lower at a
cooling rate of 200°C/sec or longer within 3 seconds after hot rolling is performed,
annealing is not performed between the hot rolling and the cold rolling, and a
cumulative rolling reduction in the cold rolling is set to 88 % or more. As a result, it
is possible to manufacture an electrical steel sheet that is accumulated on a surface of
the steel sheet in the { 100 }<011> orientation.
[0005]
Further, Patent Document 2 discloses a method for manufacturing an
electrical steel sheet containing Al of 0.6 mass% or more and 3.0 mass% or les s, in
which an electrical steel sheet that { 100}<011> orientation is accumulated on a surface
of the steel sheet can be manufactured by the same method as that in Patent Document
1.
[0006]
On the other hand, Patent Document 3 discloses that cooling is performed to a
steel sheet temperature of 250°C within 3 seconds after hot rolling while setting a
finish rolling temperature to an Ac3 transformation point or higher in hot rolling, or
cooling is performed at a cooling rate equal to or more than that the steel sheet is
allowed to cool, while setting the finish rolling temperature to the Ac3 transformation
- 2 -
point of -50°C or lower in the hot rolling. In addition, in the manufacturing method
described in Patent Document 3, first and second cold rolling are performed while
performing an intermediate annealing therebetween, the annealing is not performed
between the hot rolling and the first cold rolling, and a cumulative rolling reduction in
the second cold rolling is set to 5% to 15%. As a result, it is possible to manufacture
an electrical steel sheet that is accumulated on a surface of the steel sheet in the
{ 100}<011> orientation.
[0007]
In any of the methods described in Patent Documents 1 to 3, when the fini sh
rolling temperature in the hot rolling is an Ac3 temperature or higher at the time of
manufacturing the electrical steel sheet that is accumulated on the surface of the steel
sheet in the { 100}<011> orientation, rapid cooling immediately thereafter is required.
When the rapid cooling is performed, a cooling load after the hot rolling increases. It
is preferable that the load on a rolling mill that performs cold rolling is suppressed in
consideration of operational stability.
[0008]
On the other hand, in order to improve the magnetic characteristics, a
technology for developing a { 411} orientation rotated by 20° from a { 100 }orientation
has also been proposed. Patent Documents 4 to 7 all disclose a technology for
developing a { 411} orientation, in which the grain size of a hot-rolled sheet is
optimized or an a-fiber in a texture of the hot-rolled sheet is developed.
[0009]
Specifically, Patent Document 4 describes that cold rolling is performed on
the hot-rolled sheet having a relatively higher accumulation degree of a {211}
orientation than an accumulation degree of the { 411} orientation, and a cumulative
- 3 -
rolling reduction in the cold rolling is set to 80 % or more. Patent Document 4 also
describes that as a result, it is possible to manufacture an electrical steel sheet that is
accumulated on a surface of the steel sheet in the { 411} orientation.
[0010]
Further, Patent Documents 5 and 6 disclose that a slab heating temperature is
set to 700°C or higher and 1 ,15ooc or lower, a start temperature of finish rolling is set
to 650°C or higher and 850°C or lower, a finishing temperature of finish rolling is set
to 55ooc or higher and 800°C or lower, and a cumulative rolling reduction in the cold
rolling is set to 85% to 95%. Patent Documents 5 and 6 also disclose that as a result,
it is possible to manufacture an electrical steel sheet that is accumulated on the surface
of the steel sheet in the { 100} orientation or the { 411 } orientation.
[0011]
On the other hand, Patent Document 7 discloses a method for manufacturing a
non-oriented electrical steel sheet, in which when an a-fiber is developed in a steel
sheet of a hot-rolled coil to the vicinity of a surface layer of the steel sheet by strip
casting or the like, a {hll } orientation, particularly, { 100}<012> to
{ 411 }<148> orientations are recrystallized by subsequent annealing of the hot-rolled
sheet.
[Prior Art Document]
[Patent Document]
[0012]
[Patent Document 1] Japanese Unexamined Patent Application, First
Publication No. 2017-145462
[Patent Document 2] Japanese Unexamined Patent Application, First
Publication No. 2017-193731
- 4 -
[Patent Document 3] Japanese Unexamined Patent Application, First
Publication No. 2019-178380
[Patent Document 4] Japanese Patent No. 4218077
[Patent Document 5] Japanese Patent No. 5256916
[Patent Document 6] Japanese Unexamined Patent Application, First
Publication No. 2011-111658
[Patent Document 7] Japanese Unexamined Patent Application, First
Publication No. 2019-183185
[Summary of the Invention]
[Problems to be Solved by the Invention]
[0013]
As a result of studying the above technologies, the present inventors found
that in order to develop the { 100 }<011> orientation and improve magnetic
characteristics in accordance with Patent Documents 1 to 3, rapid cooling immediately
after the hot rolling is required, and a problem of an increased manufacturing load
occurs. Furthermore, the present inventors recognized that when a steel sheet having
the developed { 100} <0 11> orientation is used as a material for an interlocking core,
core characteristics expected from the material may not be obtained. As result of
studying, it is considable that a cause thereof is because the { 100 }<0 11> orientation
has a large change in magnetic characteristics with respect to a stress, specifically,
large deterioration of magnetic characteristics (stress sensitivity) when a compressive
stress is applied.
[0014]
Further, the present inventors found that although the { 411} orientation is
developed by the technologies in accordance with Patent Documents 4 to 7, the
- 5 -
accumulation in the <011> orientation of an in-plane orientation is weak, and the
magnetic characteristics in a 45° direction from a rolling direction of the steel sheet,
which are characteristics of the a-fiber, are not sufficiently improved. The in-plane
orientation that is not aligned in the <011> orientation, that is, having large deviation
from the a-fiber is a factor that inhibits the accumulation in the { 411} orientation as a
plane orientation, which may be a cause that the magnetic characteristics are not
sufficiently improved.
[0015]
In view of the above problems, on the premise of the manufacturing method
in which the manufacturing load is not increased, an object of the present invention is
to provide a non-oriented electrical steel sheet capable of obtaining excellent stress
sensitivity and excellent magnetic characteristics in a 45o direction, a core using the
same, a cold-rolled steel sheet for manufacturing the non-oriented electrical steel sheet,
a method for manufacturing a non -oriented electrical steel sheet, and a method for
manufacturing a cold-rolled steel sheet.
[Means for Solving the Problem]
[0016]
The present inventors have intensively studied to solve the above problems.
As a result, the present inventors found that it is important to control a chemical
composition, a ratio of crystal grains in a { 411 }<011> orientation on a plane parallel to
a rolled surface, and an average grain size. In addition, the present inventors found
that when controlling the chemical composition, the ratio of crystal grains, and the
average grain size, it is important to optimize the grain size after hot rolling and the
rolling reduction in cold rolling. Specifically, on the premise of the chemical
composition of an a -y transformation system, the present inventors found that it is
- 6 -
important to easily develop the crystal grains in the { 411 }<011> orientation, which is
normally difficult to develop, by cooling the steel sheet after the hot rolling under a
predetermined condition to optimize the grain size, cold-rolling the steel sheet at a
predetermined rolling reduction, controlling a temperature of the intermediate
annealing within a predetermined range, and performing the annealing after
performing second cold rolling at an appropriate rolling reduction. As a result of
further intensive studies based on such findings, the present inventors came up with
various aspects of the invention shown below.
[0017]
[1] According to an aspect of the present invention, a non-oriented electrical
steel sheet includes, as a chemical composition, by mass%: C: 0.0100% or les s; Si:
1.50% to 4.00%; sol.Al: 0.0001% to 1.00%; S: 0.0100% or less; N: 0.0100% or less;
one or more selected from the group consisting ofMn, Ni, and Cu: 2.5% to 5.0% in
total; Co: 0% to 1.0%; Sn: 0% to 0.40%; Sb: 0% to 0.40%; P: 0% to 0.400%; one or
more selected from the group consisting ofMg, Ca, Sr, Ba, Ce, La, Nd, Pr, Zn, and Cd:
0% to 0.010% in total; and a remainder of Fe and impurities, in which the following
Equation (1) is satisfied, where, by mass%, a Mn content is [Mn], aNi content is [Ni],
a Cu content is [Cu], a Si content is [Si], a sol.Al content is [sol.Al], and a P content
is [P], in a case where Ahkl-uvw represents an area ratio of crystal grains in an
{hkl} orientation to an entire visual field when a plane at a depth of 1/2 of a
sheet thickness from a surface parallel to a rolled surface is measured by SEM-EBSD,
A411-011 is 15.0% or more, and the average grain size is 50 J.lm to 150 J.lm.
(2 x [Mn] + 2.5 x [Ni] + [Cu]) - ([Si] + 2 x [sol.Al] + 4 x [P]) 2: 1.50% · · ·
(1)
[2] In the non-oriented electrical steel sheet to [1], when the surface is
- 7 -
measured by the SEM-EBSD to create an ODF at q>2 = 45a, the non-oriented electrical
steel sheet may have a maximum intensity at q>l = 0° to 10° among q>1 = 0° to 90°and
= 20a, and may have a maximum intensity at = sa to 35a among q> 1 = oa and =
oa to 90°.
[3] In the non-oriented electrical steel sheet to [1] or [2], an area ratio of a
specific orientation to the entire visual field when the plane at the depth of 112 of the
sheet thickness from the surface parallel to the rolled surface is measured by the SEMEBSD
may satisfy both the following Equations (2) and (3).
A411-011/A411-148 ~ 1.1 · · · (2)
A411-011/A100-011 ~ 2.0 · · · (3)
[ 4] According to another aspect of the present invention, a non-oriented
electrical steel sheet includes, as a chemical composition, by mass%: C: 0.0100% or
less; Si: 1.50% to 4.00%; sol.Al: 0.0001% to 1.00%; S: 0.0100% or less; N: 0.0100%
or less; one or more selected from the group consisting ofMn, Ni, and Cu: 2.5% to
5.0% in total; Co: 0% to 1.0%; Sn: 0% to 0.40%; Sb: 0% to 0.40%; P: 0% to 0.400%;
one or more selected from the group consisting of Mg, Ca, Sr, Ba, Ce, La, Nd, Pr, Zn,
and Cd: 0% to 0.010% in total; and a remainder of Fe and impurities, in which the
following Equation (1) is satisfied, where, by mass%, a Mn content is [Mn], aNi
content is [Ni], a Cu content is [Cu], a Si content is [Si], a sol.Al content is [sol.Al],
and a P content is [P], an area ratio Asu of crystal grains having a crystal orientation
of an a-fiber to an entire visual field when a plane at a depth of 112 of a sheet thickness
from a surface parallel to a rolled surface is measured by SEM-EBSD is 20.0% or
more, an ODF intensity in a { 100}<011> orientation when the surface is measured by
the SEM-EBSD to create an ODF is 15.0 or less, and when Gs is set as a number
average value of GOS with respect to the entire visual field when the surface is
- 8 -
measured by the SEM-EBSD, the Gs is 0.8 or more and 3.0 or less.
(2 x [Mn] + 2.5 x [Ni] + [Cu]) - ([Si] + 2 x [sol.Al] + 4 x [P]) ~ 1.50% · · ·
(1)
[5] According to still another aspect of the present invention, a core includes
the non-oriented electrical steel sheet according to any one of [1] to [3].
[6] According to still another aspect of the present invention, a core includes
the non-oriented electrical steel sheet according to [ 4].
[7] According to still another aspect of the present invention, a cold-rolled
steel sheet which is used for manufacturing the non-oriented electrical steel sheet
according to any one of [1] to [4], includes, as a chemical composition, by mass%: C:
0.0100% or less; Si: 1.50% to 4.00%; sol.Al: 0.0001% to 1.00%; S: 0.0100% or less;
N: 0.0100% or less; one or more selected from the group consisting ofMn, Ni, and Cu:
2.5% to 5.0% in total; Co: 0% to 1.0%; Sn: 0% to 0.40%; Sb: 0% to 0.40%; P: 0% to
0.400%; one or more selected from the group consisting ofMg, Ca, Sr, Ba, Ce, La, Nd,
Pr, Zn, and Cd: 0% to 0.010% in total; and a remainder of Fe and impurities, in which
the following Equation (1) is satisfied, where, by mass%, a Mn content is [Mn], aNi
content is [Ni], a Cu content is [Cu], a Si content is [Si], a sol.Al content is [sol.Al],
and a P content is [P], and an area ratio Aaa of crystal grains having a crystal
orientation of an a-fiber to an entire visual field when a plane at a depth of 1/2 of a
sheet thickness from a surface parallel to a rolled surface is measured by SEM-EBSD
is 15.0% or more.
(2 x [Mn] + 2.5 x [Ni] + [Cu]) - ([Si] + 2 x [sol.Al] + 4 x [P]) ~ 1.50% · · ·
(1)
[8] According to still another aspect of the present invention, a method for
manufacturing a non-oriented electrical steel sheet includes: a hot rolling step of
- 9 -
performing hot rolling on a steel material so that a final pass of finish rolling is
performed at an Ar3 temperature or higher to obtain a hot-rolled steel sheet, the steel
material including, as a chemical composition, by mass%: C: 0.0100% or less, Si:
1.50% to 4.00%, sol.Al: 0.0001% to 1.00%, S: 0.0100% or less, N: 0.0100% or less,
one or more selected from the group consisting of Mn, Ni, and Cu: 2.5% to 5.0% in
total, Co: 0% to 1.0%, Sn: 0% to 0.40%, Sb: 0% to 0.40%, P: 0% to 0.400%, one or
more selected from the group consisting ofMg, Ca, Sr, Ba, Ce, La, Nd, Pr, Zn, and Cd:
0% to 0.010% in total, and a remainder of Fe and impurities, in which the following
Equation (1), where, by mass%, a Mn content is [Mn], aNi content is [Ni], a Cu
content is [Cu], a Si content is [Si], a sol.Al content is [sol.Al], and a P content is [P]; a
cooling step of cooling the hot-rolled steel sheet after the hot rolling step; a cold rolling
step of performing cold rolling on the hot-rolled steel sheet after the cooling step to
obtain a cold-rolled steel sheet; an intermediate annealing step of performing
intermediate annealing on the cold-rolled steel sheet; a skin pass rolling step of
performing skin pass rolling on the cold-rolled steel sheet after the intermediate
annealing step to obtain the non-oriented electrical steel sheet; and a final annealing
step of performing final annealing on the non-oriented electrical steel sheet after the
skin pass rolling step at an annealing temperature of75oac or higher and anAc1
temperature or lower and at an annealing time of 2 hours or longer, in which in the
cooling step, the cooling is started after 0.10 seconds or longer have elapsed from the
final pass of the fini sh rolling, a temperature is set to 300°C or higher and an Ar1
temperature or lower for transformation after 3 seconds, and a rolling reduction in the
skin pass rolling step is 5% to 20%.
(2 x [Mn] + 2.5 x [Ni] + [Cu]) - ([S i] + 2 x [sol.Al] + 4 x [P]) 2: 1.50% · · ·
(1)
- 10 -
[9] According to still another aspect of the present invention, a method for
manufacturing a non-oriented electrical steel sheet includes: a hot rolling step of
performing hot rolling on a steel material so that a final pass of finish rolling is
performed at an Ar3 temperature or higher to obtain a hot-rolled steel sheet, the steel
material including, as a chemical composition, by mass%: C: 0.0100% or less, Si:
1.50% to 4.00%, sol.Al: 0.0001% to 1.00%, S: 0.0100% or less, N: 0.0100% or less,
one or more selected from the group consisting of Mn, Ni, and Cu: 2.5% to 5.0% in
total, Co: 0% to 1.0%, Sn: 0% to 0.40%, Sb: 0% to 0.40%, P: 0% to 0.400%, one or
more selected from the group consisting ofMg, Ca, Sr, Ba, Ce, La, Nd, Pr, Zn, and Cd:
0% to 0.010% in total, and a remainder of Fe and impurities, in which the following
Equation (1) is satisfied, where, by mass%, a Mn content is [Mn], aNi content is [Ni],
a Cu content is [Cu], a Si content is [Si], a sol.Al content is [sol.Al], and a P content
is [P]; a cooling step of cooling the hot-rolled steel sheet after the hot rolling step; a
cold rolling step of performing cold rolling on the hot-rolled steel sheet after the
cooling step to obtain a cold-rolled steel sheet; an intermediate annealing step of
performing intermediate annealing on the cold-rolled steel sheet; and a skin pass
rolling step of performing skin pass rolling on the cold-rolled steel sheet after the
intermediate annealing step to obtain the non-oriented electrical steel sheet, in which in
the cooling step, the cooling is started after 0.10 seconds or longer have elapsed from
the final pass of the finish rolling, a temperature is set to 300°C or higher and an Ar1
temperature or lower for transformation after 3 seconds, and a rolling reduction in the
skin pass rolling step is 5% to 20%.
(2 x [Mn] + 2.5 x [Ni] + [Cu]) - ([Si] + 2 x [sol.Al] + 4 x [P]) 2: 1.50% · · ·
(1)
[10] In the method for manufacturing a non-oriented electrical steel sheet
- 11 -
according to [8] or [9], in the cooling step, an average grain size of the hot-rolled steel
sheet after the cooling step may be 3 to 10 !Jm.
[11] In the method for manufacturing a non-oriented electrical steel sheet to
any one of [8] to [10], a rolling reduction in the cold rolling step may be 75% to 95%.
[12] In the method for manufacturing a non-oriented electrical steel sheet to
any one of [8] to [11], in the intermediate annealing step, an annealing temperature
may be set to the Acl temperature or lower.
[13] According to still another aspect of the present invention, a method for
manufacturing a cold-rolled steel sheet includes: a hot rolling step of performing hot
rolling on a steel material so that a final pass of finish rolling is performed at an Ar3
temperature or higher to obtain a hot-rolled steel sheet, the steel material including, as
a chemical composition, by mass%: C: 0.0100% or less, Si: 1.50% to 4.00%, sol.Al:
0.0001% to 1.00%, S: 0.0100% or less, N: 0.0100% or less, one or more selected from
the group consisting of Mn, Ni, and Cu: 2.5% to 5.0% in total, Co: 0% to 1.0%, Sn:
0% to 0.40%, Sb: 0% to 0.40%, P: 0% to 0.400%, one or more selected from the group
consisting of Mg, Ca, Sr, Ba, Ce, La, Nd, Pr, Zn, and Cd: 0% to 0.010% in total, and a
remainder of Fe and impurities, in which the following Equation (1) is satisfied, where,
by mass%, a Mn content is [Mn], aNi content is [Ni], a Cu content is [Cu] , a Si
content is [Si], a sol.Al content is [sol.Al], and a P content is [P]; a cooling step of
cooling the hot-rolled steel sheet after the hot rolling step ; a cold rolling step of
performing cold rolling on the hot-rolled steel sheet after the cooling step to obtain a
cold-rolled steel sheet; and an intermediate annealing step of performing intermediate
annealing on the cold-rolled steel sheet, in which in the cooling step, the cooling is
started after 0.10 seconds or longer have elapsed from the final pass of the finish
rolling, a temperature is set to 300°C or higher and an Ar1 temperature or lower for
- 12 -
transformation after 3 seconds.
(2 x [Mn] + 2.5 x [Ni] + [Cu]) - ([Si] + 2 x [sol.Al] + 4 x [P]) :=::: 1.50% · · ·
(1)
[14] In the method for manufacturing a cold-rolled steel sheet according to
[ 13], in the cooling step, an average grain size of the hot -rolled steel sheet after the
cooling step rna y be 3 to 10 J.lffi.
[15] In the method for manufacturing a cold-rolled steel sheet according to
[13] or [14], a rolling reduction in the cold rolling step may be 75% to 95%.
[16] In the method for manufacturing a cold-rolled steel sheet according to
any one of the above [13] to [15], in the intermediate annealing step, an annealing
temperature may be set to an Acl temperature or lower.
[Effects ofthe Invention]
[0018]
According to the above aspects of the present invention, it is possible to
provide a non-oriented electrical steel sheet capable of obtaining excellent stress
sensitivity and excellent magnetic characteristics in a 45a direction, a core using the
same, a cold-rolled steel sheet for manufacturing the non-oriented electrical steel sheet,
a method for manufacturing a non-oriented electrical steel sheet, and a method for
manufacturing a cold-rolled steel sheet.
[Embodiments ofthe Invention]
[0019]
According to an embodiment of the present invention, a non-oriented
electrical steel sheet (non-oriented electrical steel sheet according to the present
embodiment), a core (core according to the present embodiment), a cold-rolled steel
sheet (cold-rolled steel sheet according to the present embodiment), and manufacturing
- 13 -
methods thereof will be described hereinafter in detail.
[0020]
First, a chemical composition of a steel material (which serves as a material)
used in the non-oriented electrical steel sheet according to the present embodiment and
manufacturing the same will be described. In the following description, "%", which
is a unit of a content of each element contained in the non-oriented electrical steel
sheet or steel material, means "mass%" unless otherwise specified. In addition, a
numerical range represented by using "to" means a range including numerical values
before and after "to" as a lower limit and an upper limit.
[0021]
According to the present embodiment, a non-oriented electrical steel sheet and
a cold-rolled steel sheet have a chemical composition in which a ferrite-austenite
transformation (hereinafter referred to as a-y transformation) can occur to some extent
(chemical composition in which a constant amount ofy is generated when heated, even
if the entire composition is not transformed into y), the chemical composition
containing, by mass%: C: 0.0100% or less; Si: 1.50% to 4.00%; sol.Al: 0.0001% to
1.00%; S: 0.0100% or less; N: 0.0100% or less; one or more selected from the group
consisting of Mn, Ni, and Cu: 2.5% to 5.0% in total; Co: 0% to 1.0%; Sn: 0% to
0.40%; Sb: 0% to 0.40%; P: 0% to 0.400%; one or more selected from the group
consisting of Mg, Ca, Sr, Ba, Ce, La, Nd, Pr, Zn, and Cd: 0% to 0.010% in total; and a
remainder of Fe and impurities. Furthermore, contents ofMn, Ni, Cu, Si, sol.Al, and
P satisfy predetermined conditions to be described below. Examples of impurities
include those contained in a raw material such as ore or scrap, and those contained in a
manufacturing process.
[0022]
- 14 -
(C: 0.0100% or less)
C is an element that increases iron loss and causes magnetic aging due to
precipitation of fine carbides and inhibition of grain growth. Therefore, the lower C
content is more desirable. Such a phenomenon is remarkable when the C content
exceeds 0.0100%. Therefore, the C content is set to 0.0100% or less. The C content
is preferably 0.0050% or less, and more preferably 0.0025% or less. The lower limit
of the C content is not particularly limited, but the C content is preferably 0.0005% or
more in consideration of costs of a decarburization treatment in refining.
[0023]
(Si: 1.50% to 4.00%)
Si is an element that reduces iron loss by increasing an electric resistance and
reducing the eddy-current loss, and improves punching workability to an iron core by
increasing a yield ratio. If the Si content is less than 1.50%, these effects cannot be
sufficiently obtained. Therefore, the Si content is set to 1.50% or more.
On the other hand, when the Si content exceeds 4.00%, a magnetic flux
density is reduced, the punching workability is deteriorated due to an excessive
increase in hardness, and cold rolling is hardly performed. Therefore, the Si content
is set to 4.00% or less.
[0024]
(sol.Al: 0.0001% to 1.00%)
Sol.Al is an element that reduces iron loss by increasing the electric resistance
and reducing the eddy-current loss. Sol.Al is an element that also contributes to the
improvement in relative magnitude of a magnetic flux density B50 with respect to a
saturation magnetic flux density. Here, the magnetic flux density B50 is a magnetic
flux density in a magnetic field of 5000 Aim. If the sol.Al content is less than
- 15 -
0.0001%, these effects cannot be sufficiently obtained. In addition, Al has a
desulfurization-promoting effect in steelmaking. Therefore, the sol.Al content is
0.0001% or more.
On the other hand, if the sol.Al content exceeds 1.00%, the magnetic flux
density is reduced. Therefore, sol.Al content is set to 1.00% or less.
[0025]
(S: 0.0100% or less)
S is not an essential element, and is contained, for example, as an impurity in
steel. S is precipitated as fine MnS, and inhibits recrystallization and growth of
crystal grains during annealing. Therefore, the lower S content is more desirable.
The increase in iron loss and the reduction in magnetic flux density due to the
inhibition of the recrystallization and the growth of crystal grains are remarkable when
the S content exceeds 0.0100%. Therefore, the S content is set to 0.0100% or less.
A lower limit of the S content is not particularly limited, but the S content is preferably
0.0003% or more in consideration of costs of a desulfurization treatment in refining.
[0026]
(N: 0.0100% or less)
N deteriorates magnetic characteristics through formation of fine precipitates
such as TiN and AlN. Therefore, the lower N content is more desirable. Since such
deterioration of the magnetic characteristics is remarkable when the N content exceeds
0.0100%, theN content is set to 0.0100% or less. The lower limit of theN content is
not particularly limited, but theN content is preferably 0.0010% or more in
consideration of costs of a denitrification treatment in refining.
[0027]
(One or more selected from the group consisting of Mn, Ni, and Cu: 2.5% to
- 16 -
5.0% in total)
These elements are elements necessary for causing a-y transformation, and
thus, it is necessary to contain at least one of these elements in a total amount of 2.5%
or more.
On the other hand, if the total content exceeds 5.0%, not only the cost may
increase, but also the magnetic flux density may be reduced. Therefore, at least one
of these elements is set to 5.0% or less in total.
[0028]
Moreover, it is necessary to further satisfy the following conditions as
conditions for causing the a-y transformation and obtaining good magnetic
characteristics. That is, when the Mn content (mass%) is [Mn], the Ni content
(mass%) is [Ni], the Cu content (mass%) is [Cu], the Si content (mass%) is [Si], the
sol.Al content (mass%) is [sol.Al], and the P content (mass%) is [P], the following
Equation ( 1) is satisfied.
(2 x [Mn] + 2.5 x [Ni] + [Cu]) - ([Si] + 2 x [sol.Al] + 4 x [P]) 2: 1.50% · · ·
(1)
When Equation (1) is not satisfied, the a-y transformation does not occur, or
even if the a-y transformation occurs, a transformation point is high. Therefore, a
sufficient magnetic flux density cannot be obtained even if a manufacturing method to
be described later is applied.
[0029]
(Co: 0% to 1.0%)
Co is an element that increases the magnetic flux density. Therefore, Co
may be contained if necessary.
On the other hand, if Co is excessively contained, costs thereof becomes high.
- 17 -
Therefore, the Co content is set to 1.0% or less.
[0030]
(Sn: 0% to 0.40%, Sb: 0% to 0.40%)
Sn and Sb improve a texture after cold rolling and recrystallization to improve
the magnetic flux density. Therefore, these elements may be contained if necessary.
When further effects such as magnetic characteristics are imparted, it is preferable to
contain at least one selected from the group consisting of Sn in an amount of 0.02% to
0.40% and Sb in an amount of 0.02% to 0.40%.
On the other hand, if these elements are excessively contained, the steel
becomes brittle. Therefore, both the Sn content and the Sb content are set to 0.40%
or less.

What is claimed is:
CLAIMS
1. A non-oriented electrical steel sheet comprising, as a chemical
composition, by mass%:
C: 0.0100% or less;
Si: 1.50% to 4.00%;
sol.Al: 0.0001% to 1.00%;
S: 0.0100% or less;
N: 0.0100% or less;
one or more selected from the group consisting ofMn, Ni, and Cu: 2.5% to
5.0% in total;
Co: 0% to 1.0%;
Sn: 0% to 0.40%;
Sb: 0% to 0.40%;
P: 0% to 0.400%;
one or more selected from the group consisting ofMg, Ca, Sr, Ba, Ce, La, Nd,
Pr, Zn, and Cd: 0% to 0.010% in total; and
a remainder of Fe and impurities,
wherein the following Equation (1) is satisfied, where, by mass%, a Mn
content is [Mn], aNi content is [Ni], a Cu content is [Cu], a Si content is [Si], a sol.Al
content is [sol.Al], and a P content is [P],
in a case where Ahkl-uvw represents an area ratio of crystal grains in an
{hkl} orientation to an entire visual field when a plane at a depth of 1/2 of a
sheet thickness from a surface parallel to a rolled surface is measured by SEM-EBSD,
A411 -0ll is 15.0% or more, and
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an average grain size is 50 11m to 150 11m,
(2 x [Mn] + 2.5 x [Ni] + [Cu])- ([Si] + 2 x [sol.A1] + 4 x [P]) ~ 1.50% · · · (1).
2. The non-oriented electrical steel sheet according to claim 1,
wherein when the surface is measured by the SEM-EBSD to create an ODF at
<:p2 = 45°, the non-oriented electrical steel sheet has a maximum intensity at <:p1 = 0° to
10° among <:p1 = 0° to goo and orientation when the surface is measured by the
SEM-EBSD to create an ODF is 15.0 or less, and
when Gs is set as a number average value of GOS with respect to the entire
visual field when the surface is measured by the SEM-EBSD, the Gs is 0.8 or more and
3.0 or less,
(2 x [Mn] + 2.5 x [Ni] + [Cu])- ([Si] + 2 x [sol.Al] + 4 x [P]) ~ 1.50% · · · (1).
5. A core comprising the non-oriented electrical steel sheet according to any
one of claims 1 to 3.
6. A core comprising the non-oriented electrical steel sheet according to
claim 4.
7. A cold-rolled steel sheet which is used for manufacturing the non-oriented
electrical steel sheet according to any one of claims 1 to 4, the cold-rolled steel sheet
comprising, as a chemical composition, by mass%:
C: 0.0100% or less;
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Si: 1.50% to 4.00%;
sol.Al: 0.0001% to 1.00%;
S: 0.0100% or less;
N: 0.0100% or less;
one or more selected from the group consisting ofMn, Ni, and Cu: 2.5% to
5.0% in total;
Co: 0% to 1.0%;
Sn: 0% to 0.40%;
Sb: 0% to 0.40%;
P: 0% to 0.400%;
one or more selected from the group consisting ofMg, Ca, Sr, Ba, Ce, La, Nd,
Pr, Zn, and Cd: 0% to 0.010% in total; and
a remainder of Fe and impurities,
wherein the following Equation (1) is satisfied, where, by mass%, a Mn
content is [Mn], aNi content is [Ni], a Cu content is [Cu], a Si content is [Si], a sol.Al
content is [sol.Al], and a P content is [P], and
an area ratio Aau of crystal grains having a crystal orientation of an a-fiber to an
entire visual field when a plane at a depth of 112 of a sheet thickness from a surface
parallel to a rolled surface is measured by SEM-EBSD is 15.0% or more,
(2 x [Mn] + 2.5 x [Ni] + [Cu])- ([Si] + 2 x [sol.Al] + 4 x [P]) 2: 1.50% · · · (1).
8. A method for manufacturing a non-oriented electrical steel sheet, the
method comprising:
a hot rolling step of performing hot rolling on a steel material so that a final
pass of fini sh rolling is performed at an Ar3 temperature or higher to obtain a hot-rolled
steel sheet, the steel material including, as a chemical composition, by mass%: C:
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0.0100% or less, Si: 1.50% to 4.00%, sol.Al: 0.0001% to 1.00%, S: 0.0100% or less, N:
0.0100% or less, one or more selected from the group consisting ofMn, Ni, and Cu:
2.5% to 5.0% in total, Co: 0% to 1.0%, Sn: 0% to 0.40%, Sb: 0% to 0.40%, P: 0% to
0.400%, one or more selected from the group consisting ofMg, Ca, Sr, Ba, Ce, La, Nd,
Pr, Zn, and Cd: 0% to 0.010% in total, and a remainder of Fe and impurities, in which
the following Equation (1) is satisfied, where, by mass%, a Mn content is [Mn], aNi
content is [Ni], a Cu content is [Cu], a Si content is [Si], a sol.Al content is [sol.Al], and
a P content is [P];
a cooling step of cooling the hot-rolled steel sheet after the hot rolling step;
a cold rolling step of performing cold rolling on the hot-rolled steel sheet after
the cooling step to obtain a cold-rolled steel sheet;
an intermediate annealing step of performing intermediate annealing on the
cold-rolled steel sheet;
a skin pass rolling step of performing skin pass rolling on the cold-rolled steel
sheet after the intermediate annealing step to obtain the non-oriented electrical steel
sheet; and
a final annealing step of performing final annealing on the non-oriented
electrical steel sheet after the skin pass rolling step at an annealing temperature of
750°C or higher and an Acl temperature or lower and at an annealing time of 2 hours or
longer,
wherein in the cooling step, the cooling is started after 0.10 seconds or longer
have elapsed from the final pass of the finish rolling, a temperature is set to 300°C or
higher and an Ar1 temperature or lower for transformation after 3 seconds, and
a rolling reduction in the skin pass rolling step is 5% to 20%,
(2 x [Mn] + 2.5 x [Ni] + [Cu]) - ([Si] + 2 x [sol.Al] + 4 x [P]) 2: 1.50% · · · (1).
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9. A method for manufacturing a non-oriented electrical steel sheet, the
method comprising:
a hot rolling step of performing hot rolling on a steel material so that a final
pass of finish rolling is performed at an Ar3 temperature or higher to obtain a hot-rolled
steel sheet, the steel material including, as a chemical composition, by mass%: C:
0.0100% or less, Si: 1.50% to 4.00%, sol.Al: 0.0001% to 1.00%, S: 0.0100% or less, N:
0.0100% or less, one or more selected from the group consisting ofMn, Ni, and Cu:
2.5% to 5.0% in total, Co: 0% to 1.0%, Sn: 0% to 0.40%, Sb: 0% to 0.40%, P: 0% to
0.400%, one or more selected from the group consisting ofMg, Ca, Sr, Ba, Ce, La, Nd,
Pr, Zn, and Cd: 0% to 0.010% in total, and a remainder ofFe and impurities, in which
the following Equation (1) is satisfied, where, by mass%, a Mn content is [Mn], aNi
content is [Ni], a Cu content is [Cu], a Si content is [Si], a sol.Al content is [sol.Al], and
a P content is [P];
a cooling step of cooling the hot-rolled steel sheet after the hot rolling step;
a cold rolling step of performing cold rolling on the hot-rolled steel sheet after
the cooling step to obtain a cold-rolled steel sheet;
an intermediate annealing step of performing intermediate annealing on the
cold-rolled steel sheet; and
a skin pass rolling step of performing skin pass rolling on the cold-rolled steel
sheet after the intermediate annealing step to obtain the non-oriented electrical steel
sheet,
wherein in the cooling step, the cooling is started after 0.10 seconds or longer
have elapsed from the final pass of the finish rolling, a temperature is set to 300°C or
higher and an Ar1 temperature or lower for transformation after 3 seconds, and
a rolling reduction in the skin pass rolling step is 5% to 20%,
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(2 x [Mn] + 2.5 x [Ni] + [Cu])- ([Si] + 2 x [sol.Al] + 4 x [P]) 2: 1.50% · · · (1).
10. The method for manufacturing a non-oriented electrical steel sheet
according to claims 8 or 9,
wherein in the cooling step, an average grain size of the hot-rolled steel sheet
after the cooling step is 3 to 10 J.lm.
11. The method for manufacturing a non-oriented electrical steel sheet
according to any one of claims 8 to 10,
wherein a rolling reduction in the cold rolling step is 75% to 95%.
12. The method for manufacturing a non-oriented electrical steel sheet
according to any one of claims 8 to 11,
wherein in the intermediate annealing step, an annealing temperature is set to
the Acl temperature or lower.
13. A method for manufacturing a cold-rolled steel sheet, the method
compnsmg:
a hot rolling step of performing hot rolling on a steel material so that a final
pass of finish rolling is performed at an Ar3 temperature or higher to obtain a hot-rolled
steel sheet, the steel material including, as a chemical composition, by mass%: C:
0.0100% or less, Si: 1.50% to 4.00%, sol.Al: 0.0001% to 1.00%, S: 0.0100% or less, N:
0.0100% or less, one or more selected from the group consisting ofMn, Ni, and Cu:
2.5% to 5.0% in total, Co: 0% to 1.0%, Sn: 0% to 0.40%, Sb: 0% to 0.40%, P: 0% to
0.400%, one or more selected from the group consisting ofMg, Ca, Sr, Ba, Ce, La, Nd,
Pr, Zn, and Cd: 0% to 0.010% in total, and a remainder of Fe and impurities, in which
the following Equation (1) is satisfied, where, by mass%, a Mn content is [Mn], aNi
content is [Ni], a Cu content is [Cu], a Si content is [Si], a sol.Al content is [sol.Al], and
a P content is [P] ;
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a cooling step of cooling the hot-rolled steel sheet after the hot rolling step;
a cold rolling step of performing cold rolling on the hot-rolled steel sheet after
the cooling step to obtain a cold-rolled steel sheet; and
an intermediate annealing step of performing intermediate annealing on the
cold-rolled steel sheet,
wherein in the cooling step, the cooling is started after 0.10 seconds or longer
have elapsed from the final pass of the finish rolling, a temperature is set to 300°C or
higher and an Ar1 temperature or lower for transformation after 3 seconds,
(2 x [Mn] + 2.5 x [Ni] + [Cu]) - ([Si] + 2 x [sol.Al] + 4 x [P]) ~ 1.50% · · · (1).
14. The method for manufacturing a cold-rolled steel sheet according to
claim 13,
wherein in the cooling step, an average grain size of the hot-rolled steel sheet
after the cooling step is 3 to 10 ~J.m.
15. The method for manufacturing a cold-rolled steel sheet according to
claims 13 or 14,
wherein a rolling reduction in the cold rolling step is 75% to 95%.
16. The method for manufacturing a cold-rolled steel sheet according to any
one of claims 13 to 15,
wherein in the intermediate annealing step, an annealing temperature is set to
an Ac 1 temperature or lower.