[0001]The present invention relates to a non oriented electrical steel sheet excellent in magnetic characteristics and punchability, and a method for producing thereof.
10 B ackground Art [0002]
In recent years, especially in the field of electrical equipment such as rotating machines, small and medium-size transformers, and electrical components, it is eagerly demanded for a motor to enhance the efficiency and to reduce the size, due to the 15 movement of global environmental conservation represented by global power reduction, energy saving, and CO2 emission reduction. Under the social situation, it is demanded to improve the performance for the non oriented electrical steel sheet used as motor core materials.
[0003]
20 For instance, in the automotive field, the non oriented electrical steel sheet is
used as the core of drive motor for hybrid drive vehicles (HEV: Hybrid Electric Vehicle)
and the like. Moreover, it is demanded to reduce the size of drive motor used in HEV in
order to save installation space and to reduce fuel consumption by weight reduction.
[0004]
25 To reduce the size of drive motor, it is necessary to increase the torque of motor.

2 Thus, it is demanded to further improve the magnetic flux density of the non oriented
electrical steel sheet. Moreover, since the battery capacity that can be mounted on the
automobile is limited, it is needed to reduce the energy loss in the motor. Thus, it is
demanded to further decrease the iron loss of the non oriented electrical steel sheet.
5 [0005]
In addition, among the motor cores to which the non oriented electrical steel
sheet is applied, for instance, there is a "split core". In the split core, the winding is
wound around the cores divided into individual teeth, and then the cores are assembled to
be the final form of the stator core.
10 [0006]
The split core is often applied to a core having a complicated shape, and the
shape thereof needs to particularly have high accuracy. However, the electrical steel
sheet which is sufficiently heat-treated to coarsen the grains for reducing the iron loss
becomes soft, and thereby, the shape accuracy may deteriorate when the member (steel
15 sheet blank) is punched.
[0007]
For the deterioration of the shape accuracy, for instance, Patent Documents 1 to
3 disclose the technique to improve the punching accuracy by hardening the steel sheet or
by refining the grains. However, by the above techniques, the punching accuracy may
20 be improved, but the magnetic characteristics such as magnetic flux density and iron loss
may not sufficiently satisfy the demands of recent years.
Related Art Documents
Patent Documents
25 [0008]

3 [Patent Document 1] PCT International Publication No. WO2003/002777
[Patent Document 2] Japanese Unexamined Patent Application, First
Publication No. 2003-197414
[Patent Document 3] Japanese Unexamined Patent Application, First
5 Publication No. 2004-152791
Summary of Invention Technical Problem to be Solved [0009]
10 In conventional techniques, the technique which simultaneously improves both
the punching accuracy and the magnetic characteristics has not been established. If it is possible to simultaneously improve both the punching accuracy and the magnetic characteristics for the non oriented electrical steel sheet used to the split core, it is possible to satisfy the demands for the motor to enhance the efficiency and to reduce the
15 size.
[0010]
An object of the present invention is to simultaneously improve both the accuracy of punching (punchability) and the magnetic characteristics for the split core. In particular, the object of the present invention is to simultaneously improve both the
20 punchability and the magnetic characteristics in two directions of the rolling direction and the transverse direction for the motor core. Specifically, the object of the present invention is to provide the non oriented electrical steel sheet excellent in the punchability and the magnetic characteristics, and a method for producing thereof.
25 Solution to Problem

4 [0011]
The present inventors have made a thorough investigation to solve the above
mentioned situations. As a result, it is found that, when the alignment degree to {5 5
7}<7 14 5> orientation in the central area along the thickness direction of the base steel
5 sheet is made to increase, it is possible to improve both the punchability and the magnetic
characteristics.
[0012]
Moreover, the present inventors have made a thorough investigation about the
conditions to make the alignment degree to {5 5 7}<7 14 5> orientation in the central
10 area along the thickness direction increase. As a result, it is found that, when the ratio
of recrystallized structure and non-recrystallized structure in the steel sheet before cold
rolling is controlled by controlling each process, it is possible to make the alignment
degree to {5 5 7}<7 14 5> orientation in the central area along the thickness direction
increase after subsequent cold rolling and final annealing.
15 [0013]
An aspect of the present invention employs the following.
[0014]
(1) A non oriented electrical steel sheet according to an aspect of the present
invention consists of a silicon steel sheet and an insulation coating, characterized in that
20 the silicon steel sheet contains, as a chemical composition, by mass%,
0.01 to 3.50% of Si,
0.001 to 2.500% of Al,
0.01 to 3.00% of Mn,
0.0030% or less of C,
25 0.180% or less of P,

5 0.003% or less of S,
0.003% or less of N,
0.002% or less of B,
0to0.05%ofSb,
5 0to0.20%ofSn,
0tol.00%ofCu,
0 to 0.0400% of REM,
0 to 0.0400% of Ca,
0 to 0.0400% of Mg, and
10 a balance consisting of Fe and impurities, and
an alignment degree to{557}<7 145> orientation in a central area along a
thickness direction of the silicon steel sheet is 12 to 35.
(2) In the non oriented electrical steel according to (1), the silicon steel sheet
may contain, as the chemical composition, by mass%, at least one selected from a group
15 consisting of
0.001 to 0.05% of Sb,
0.01 to 0.20% of Sn,
0.10 to 1.00% of Cu,
0.0005 to 0.0400% of REM,
20 0.0005 to 0.0400% of Ca, and
0.0005 to 0.0400% of Mg.
(3) In the non oriented electrical steel according to (1) or (2), the alignment degree to{557}<7 145> orientation may be 18 to 35.
(4) A method for producing a non oriented electrical steel according to an
25 aspect of the present invention is for producing the non oriented electrical steel according

6 to any one of (1) to (3), and the method may contain a casting process, a hot rolling
process, an heat conservation process, a pickling process, a cold rolling process, a final
annealing process, and a coating formation process, wherein
in the casting process, a slab is cast, the slab containing, as a chemical
5 composition, by mass%,
0.01 to 3.50% of Si,
0.001 to 2.500% of Al,
0.01 to 3.00% of Mn,
0.0030% or less of C,
10 0.180% or less of P,
0.003% or less of S,
0.003% or less of N,
0.002% or less of B,
0to0.05%ofSb,
15 0to0.20%ofSn,
0tol.00%ofCu,
0 to 0.0400% of REM,
0 to 0.0400% of Ca,
0 to 0.0400% of Mg, and
20 a balance consisting of Fe and impurities,
in the hot rolling process, a slab heating temperature before hot rolling is 1000
to 1300°C, a finish rolling temperature for final hot rolling is 800 to 950°C, a cumulative
reduction of hot rolling is 98 to 99.5%, and an average cooling rate from a temperature
after finishing the hot rolling to a heat conservation temperature for heat conservation
25 treatment is 80 to 200 °C/second,

7 in the heat conservation process, the heat conservation temperature is 700 to
850°C and a heat conservation time is 10 to 180 minutes,
before the cold rolling process, a fraction of non-recrystallized grains in a steel
sheet is controlled to be 10 to 20 area%,
5 in the cold rolling process, a cumulative reduction of cold rolling is 80 to 95%,
and
in the final annealing process, an average heating rate from a heating start temperature to 750°C is 5 to 50 °C/second, an average heating rate from 750°C to a holding temperature for final annealing is changed to a heating rate which is faster than 10 the average heating rate to 750°C and which is within a range of 20 to 100 °C/second, and the holding temperature for final annealing is a recrystallization temperature or higher.
Effects of Invention
15 [0015]
According to the above aspects of the present invention, it is possible to provide the non oriented electrical steel sheet excellent in both the punchability and the magnetic characteristics in two directions of the rolling direction and the transverse direction for the split core, and the method for producing thereof. 20
Brief Description of Drawings [0016]
Fig. 1 is a cross sectional illustration of a non oriented electrical steel sheet
according to an embodiment of the present invention.
25 Fig. 2 is a flow chart illustrating a producing method for the non oriented

8 electrical steel sheet according to the embodiment.
Fig. 3 is an illustration showing an instance of motor core.
Fig. 4 is a diagram showing a relation of the alignment degree to {5 5 7}<7 14
5> orientation and roundness.
5
Detailed Description of Preferred Embodiments
[0017]
Hereinafter, a preferable embodiment of the present invention is described in
detail. However, the present invention is not limited only to the configuration which is
10 disclosed in the embodiment, and various modifications are possible without departing
from the aspect of the present invention. In addition, the limitation range as described
below includes a lower limit and an upper limit thereof. However, the value expressed
by "more than" or "less than" does not include in the limitation range. "%" of the
amount of respective elements expresses "mass%".
15 [0018]
A non oriented electrical steel sheet according to the embodiment includes a
silicon steel sheet as base steel sheet and an insulation coating. Fig. 1 is a cross
sectional illustration of the non oriented electrical steel sheet according to the
embodiment. The non oriented electrical steel sheet 1 according to the embodiment
20 includes the silicon steel sheet 3 and the insulation coating 5 when viewing a cross
section whose cutting direction is parallel to a thickness direction. In addition, in the
embodiment, the alignment degree to {5 5 7}<7 14 5> orientation in the central area
along the thickness direction of the silicon steel sheet is 12 or more.
[0019]
25 (Texture of Silicon Steel Sheet)

9 In the embodiment, it is needed to control the alignment degree to {5 5 7}<7 14
5> orientation in the central area along the thickness direction of the silicon steel sheet to
be 12 or more.
[0020]
5 In the embodiment, for instance, the {1 1 1 }<1 1 2> orientation, the {5 5 7}<7
14 5> orientation, and the like correspond to the orientation including orientations within
±5°, regarding the miller index of the direction perpendicular to rolled surface (normal
direction) and the miller index of the direction parallel to the rolling direction (in-plane
direction).
10 [0021]
The {5 5 7}<7 14 5> orientation is the orientation relatively close to the {1 1 1}
orientation which is favorable for improving the punching accuracy. Also, the {5 5
7}<7 14 5> orientation is the orientation relatively close to the {4 11 }<1 4 8>
orientation which is favorable for improving the magnetic characteristics. Therefore,
15 when the alignment degree to {5 5 7}<7 14 5> orientation in the central area along the
thickness direction of the silicon steel sheet to increase, it is possible to improve both the
punchability and the magnetic characteristics.
[0022]
When the alignment degree to {5 5 7}<7 14 5> orientation is 12 or more, it is
20 possible to improve both the punchability and the magnetic characteristics. The
alignment degree to {5 5 7}<7 14 5> orientation is preferably 15 or more, and more
preferably 18 or more. On the other hand, since it is preferable that the alignment
degree to {5 5 7}<7 14 5> orientation is as high as possible, the upper limit thereof is not
particularly limited. However, since it is substantially difficult to control the alignment
25 degree to {5 5 7 }<7 14 5> orientation to be more than 35, the upper limit thereof may be

10 35 or less. The upper limit thereof may be 30 or less, and may be 25 or less.
[0023]
The control for making the alignment degree to{557}<7 145> orientation in
the central area along the thickness direction of the silicon steel sheet increase is
5 explained below.
[0024]
The alignment degree of crystal orientation may be measured by the following
method. When t is the thickness of the silicon steel sheet, the central area is regarded as
the position of 1/2 t from the surface of silicon steel sheet along the thickness direction.
10 A sample with approximately 30 mm x 30 mm is cut out from the steel sheet, the sheet
surface of the sample is mechanically polished to reduce the thickness of the sample, and
thereby the central area is exposed. The exposed surface is chemical-polished or
electrolytic-polished to remove the strain, and thereby the measurement sample is
obtained.
15 [0025]
X-ray diffraction is conducted using the measurement sample, and the pole
figures of {2 0 0} plane, {110} plane, and {211} plane are obtained. From the above
pole figures, the orientation determination function ODF of the central area is obtained.
Based on the orientation determination function, the alignment degree to {5 5 7}<7 14 5>
20 orientation is obtained.
[0026]
(Chemical Composition of Silicon Steel Sheet)
In the embodiment, the silicon steel sheet contains, as a chemical composition,
base elements, optional elements as necessary, and a balance consisting of Fe and
25 impurities. "%" related to the chemical composition expresses "mass%".

11
[0027]
In the embodiment, Si, Al, and Mn are the base elements (main alloying elements) in the chemical composition of the silicon steel sheet. [0028] 5 0.01 to 3.50% of Si
Si (silicon) is an element which decreases the magnetic flux density, decreases
workability during production by hardening the steel sheet, and decreases the
punchability. On the other hand, Si is the element which reduces eddy current loss by
increasing the electrical resistance of steel sheet, and thereby reduces the iron loss.
10 [0029]
When the Si content is more than 3.50%, the magnetic flux density and the punchability deteriorate excessively, and the production cost increases. Thus, the Si content is to be 3.50% or less. The Si content is preferably 3.20% or less, and more preferably 3.00% or less. On the other hand, when the Si content is less than 0.01%, the 15 electrical resistance of steel sheet does not increase, and the iron loss is not reduced. Thus, the Si content is to be 0.01% or more. The Si content is preferably 0.10% or more, more preferably 0.50% or more, further more preferably more than 2.00%, further more preferably 2.10% or more, and further more preferably 2.30% or more. [0030] 20 0.001 to 2.500% of Al
Al (aluminum) is an element which is unavoidably contained in ores and
refractories, and is also used for deoxidation. In common with Si, Al (aluminum) is the
element which has the effect of reducing the eddy current loss by increasing the electrical
resistance, and thereby reducing the iron loss.
25 [0031]

12 When the Al content is less than 0.001%, the deoxidation becomes insufficient,
the electrical resistance of steel sheet does not increase, and the iron loss is not reduced.
Thus, the Al content is to be 0.001% or more. The Al content is preferably 0.010% or
more, more preferably 0.050% or more, further more preferably more than 0.50%, and
5 further more preferably 0.60% or more.
[0032]
On the other hand, when the Al content is more than 2.500%, the magnetic flux
density decreases because the saturation magnetic flux density decreases. Thus, the Al
content is to be 2.500% or less. The Al content is preferably 2.000% or less, and more
10 preferably 1.600% or less.
[0033]
0.01 to 3.00% of Mn
Mn (manganese) is an element which has the effect of reducing the eddy current
loss by increasing the electrical resistance and of suppressing the formation of {111}
15 <112> texture which is undesirable for magnetic characteristics.
[0034]
When the Mn content is less than 0.01%, the addition effect is not sufficiently
obtained. Thus, the Mn content is to be 0.01% or more. The Mn content is preferably
0.15% or more, more preferably 0.40% or more, further more preferably more than
20 0.60%, and further more preferably 0.70% or more. On the other hand, when the Mn
content is more than 3.00%, the grain growth during annealing is suppressed, and the
iron loss deteriorates. Thus, the Mn content is to be 3.00% or less. The Mn content is
preferably 2.50% or less, and more preferably 2.00% or less.
[0035]
25 In the embodiment, the silicon steel sheet contains the impurities as the chemical

13 composition. The impurities correspond to elements which are contaminated during
industrial production of steel from ores and scrap that are used as a raw material of steel,
or from environment of a production process. For instance, the impurities are elements
such as C, P, S, N, and B. It is preferable that the impurities are limited as follows in
5 order to sufficiently obtain the effects of the embodiment. Moreover, since it is
preferable that the amount of respective impurities is low, a lower limit of the respective
impurities does not need to be limited, and the lower limit may be 0%.
[0036]
0.0030% or less of C
10 C (carbon) is an impurity element which causes the deterioration of the iron loss
and the magnetic aging. It is preferable that the C content is as low as possible, and
thus, the C content is to be 0.0030% or less. The C content is preferably 0.0025% or
less, and more preferably 0.0020% or less. The lower limit of the C content is not
particularly limited. In consideration of industrial purification technology, the lower
15 limit thereof may be 0.0001% practically. In consideration of producing cost, the lower
limit thereof is preferably 0.0005% or more.
[0037]
0.180% or less of P
Although P (phosphorus) may contribute to the improvement of the tensile
20 strength without decreasing the magnetic flux density, P is an impurity element which
embrittles the steel sheet. When the P content is more than 0.180%, the toughness
deteriorates, and the steel sheet tends to be fractured. Thus, the P content is to be
0.180% or less.
[0038]
25 It is preferable that the P content is as low as possible in order to suppress the

14 fracture of steel sheet. The P content is preferably 0.150% or less, and more preferably
0.120% or less. The lower limit of the P content is not particularly limited. In
consideration of industrial purification technology, the lower limit thereof may be
0.0001% practically. In consideration of producing cost, the lower limit thereof is
5 preferably 0.001%.
[0039]
0.003% or less of S
S (sulfur) is an impurity element which forms fine sulfides such as MnS, and
thus, suppresses the recrystallization and the grain growth during final annealing. When
10 the S content is more than 0.003%, the recrystallization and the grain growth during final
annealing are suppressed significantly. Thus, the S content is to be 0.003% or less. It
is preferable that the S content is as low as possible. The S content is preferably
0.002% or less, and more preferably 0.001% or less.
[0040]
15 The lower limit of the S content is not particularly limited. In consideration of
industrial purification technology, the lower limit thereof may be 0.0001% practically.
In consideration of producing cost, the lower limit thereof is preferably 0.0005%.
[0041]
0.003% or less of N
20 N (nitrogen) is an impurity element which deteriorates the iron loss by forming
precipitates. When the N content is more than 0.003%, the iron loss deteriorates
excessively. Thus, the N content is to be 0.003% or less. The N content is preferably
0.002% or less, and more preferably 0.001% or less. The lower limit of the N content is
not particularly limited. In consideration of industrial purification technology, the lower
25 limit thereof may be 0.0001% practically. In consideration of producing cost, the lower

15 limit thereof is preferably 0.0005%.
[0042]
0.002% or less of B
B (boron) is an impurity element which deteriorates the iron loss by forming
5 precipitates. When the B content is more than 0.002%, the iron loss deteriorates
excessively. Thus, the B content is to be 0.002% or less. The B content is preferably
0.001% or less, and more preferably 0.0005% or less. The lower limit of the B content
is not particularly limited. In consideration of industrial purification technology, the
lower limit thereof may be 0.0001% practically. In consideration of producing cost, the
10 lower limit thereof is preferably 0.0005%.
[0043]
In the embodiment, the silicon steel sheet may contain the optional element in
addition to the base elements and the impurities described above. For instance, as
substitution for a part of Fe which is the balance described above, as the optional element,
15 the steel sheet may contain Sb, Sn, Cu, REM, Ca, and Mg. The optional elements may
be contained as necessary. Thus, a lower limit of the optional element does not need to
be limited, and the lower limit may be 0%. Moreover, even if the optional element may
be contained as impurities, the above mentioned effects are not affected.
[0044]
20 0to0.05%ofSb
Sb (antimony) is an element which suppresses the surface nitridation of steel
sheet, and contributes to the improvement of iron loss. When the Sb content is more
than 0.05%, the toughness of steel deteriorates. Thus, the Sb content is to be 0.05% or
less. The Sb content is preferably 0.03% or less, and more preferably 0.01% or less.
25 The lower limit of the Sb content is not particularly limited, and may be 0%. The Sb

16 content may be 0.001% or more in order to obtain the above effects preferably.
[0045]
0to0.20%ofSn
Sn (tin) is an element which suppresses the surface nitridation of steel sheet, and
5 contributes to the improvement of iron loss. When the Sn content is more than 0.20%,
the toughness of steel deteriorates, and the insulation coating tends to be delaminated.
Thus, the Sn content is to be 0.20% or less. The Sn content is preferably 0.15% or less,
and more preferably 0.10% or less. The lower limit of the Sn content is not particularly
limited, and may be 0%. The Sn content may be 0.01% or more in order to obtain the
10 above effects preferably. The Sn content is preferably 0.04% or more, and more
preferably 0.08% or more.
[0046]
0tol.00%ofCu
Cu (copper) is the element which has the effects of suppressing the formation of
15 {111} <112> texture which is undesirable for magnetic characteristics, of suppressing the
oxidation of steel sheet surface, and of controlling the grain growth to be uniform.
When the Cu content exceeds 1.00%, the effects of addition are saturated, the grain
growth during final annealing is suppressed, the workability of steel sheet deteriorates,
and the steel sheet becomes brittle during cold rolling. Thus, the Cu content is to be
20 1.00% or less. The Cu content is preferably 0.60% or less and more preferably 0.40%
or less. The lower limit of Cu content is not particularly limited, and may be 0%. The
Cu content may be 0.10% or more in order to obtain the above effects preferably. The
Cu content is preferably 0.20% or more and more preferably 0.30% or more.
[0047]
25 0 to 0.0400% of REM

17 0 to 0.0400% of Ca
0 to 0.0400% of Mg
REM (Rare Earth Metal), Ca (calcium), and Mg (magnesium) are the elements
which have the effects of fixing S as sulfides or oxysulfides, of suppressing the fine
5 precipitation of MnS and the like, and of promoting the recrystallization and grain
growth during final annealing.
[0048]
When REM, Ca, and Mg exceed 0.0400%, the sulfides or oxysulfides are
excessively formed, and the recrystallization and grain growth during final annealing are
10 suppressed. Thus, the REM content, the Ca content, and the Mg content are to be
0.0400% or less respectively. The respective contents are preferably 0.0300% or less
and more preferably 0.0200% or less.
[0049]
The lower limits of REM content, Ca content, and Mg content are not
15 particularly limited, and may be 0%. The REM content, the Ca content, and the Mg
content may be 0.0005% or more in order to obtain the above effects preferably. The
respective contents are preferably 0.0010% or more and more preferably 0.0050% or
more.
[0050]
20 Herein, REM indicates a total of 17 elements of Sc, Y and lanthanoid, and is at
least one of them. The above REM content corresponds to the total content of at least
one of these elements. Industrially, misch metal is added as the lanthanoid.
[0051]
In the embodiment, it is preferable that the silicon steel sheet contains, as the
25 chemical composition, by mass%, at least one selected from the group consisting of

18 0.001 to 0.05% of Sb, 0.01 to 0.20% of Sn, 0.10 to 1.00% of Cu, 0.0005 to 0.0400% of
REM, 0.0005 to 0.0400% of Ca, or 0.0005 to 0.0400% of Mg.
[0052]
The steel composition as described above may be measured by typical analytical
5 methods for steel. For instance, the steel composition may be measured by using
ICP-AES (Inductively Coupled Plasma-Atomic Emission Spectrometer: inductively
coupled plasma emission spectroscopy spectrometry). In addition, C and S may be
measured by the infrared absorption method after combustion, N may be measured by the
thermal conductometric method after fusion in a current of inert gas, and O may be
10 measured by, for instance, the non-dispersive infrared absorption method after fusion in a
current of inert gas.
[0053]
The above chemical composition is that of the silicon steel sheet. When the
non oriented electrical steel sheet to be the measurement sample has the insulation
15 coating and the like on the surface, the above chemical composition is obtained after
removing the coating.
[0054]
As a method for removing the insulation coating and the like of the non oriented
electrical steel sheet, for instance, the following method is exemplified. First, the non
20 oriented electrical steel sheet having the insulation coating and the like is immersed in
sodium hydroxide aqueous solution, sulfuric acid aqueous solution, and nitric acid
aqueous solution in this order. The steel sheet after the immersion is washed. Finally,
the steel sheet is dried with warm air. Thereby, it is possible to obtain the silicon steel
sheet from which the insulation coating is removed.
25 [0055]

19 (Magnetic Characteristics of Electrical Steel Sheet)
It is preferable that the non oriented electrical steel sheet according to the
embodiment shows excellent magnetic characteristics in regard to the two directions
which are the rolling direction and the transverse direction (the direction perpendicular to
5 the rolling direction) for the split core. Thus, when the magnetic flux density B50 is
defined as the average of the magnetic flux density in rolling direction and the magnetic
flux density in transverse direction under conditions such that the steel sheet is excited
under magnetic field strength of 5000 A/m, and when the saturation magnetic flux
density Bs is defined as the average of the saturation magnetic flux density of rolling
10 direction and the saturation magnetic flux density of transverse direction, it is preferable
that the ratio B50 / Bs of the magnetic flux density B50 to the saturation magnetic flux
density Bs is 0.82 or more.
[0056]
The ratio B50 / Bs is preferably 0.84 or more, more preferably 0.86 or more, and
15 further more preferably 0.90 or more. On the other hand, since the saturation magnetic
flux density Bs is the maximum magnetic flux density obtained when the maximum
magnetic field is applied, the maximum of the ratio B50 / Bs is 1. The upper limit of the
ratio B50 / Bs is not particularly limited, and may be 1.00. The ratio B50 / Bs is
preferably 0.98 or less.
20 [0057]
The {5 5 7}<7 14 5> orientation which is controlled in the embodiment is the
orientation relatively close to the {4 1 1 }<1 4 8> orientation, and the {4 1 1 }<1 4 8>
orientation is the orientation relatively close to the {1 0 0}<0 1 2> orientation which
improves the magnetic flux density B50 of the rolling direction and the transverse
25 direction. Thus, it seems that the magnetic characteristics in two directions of the

20 rolling direction and the transverse direction are improved in the embodiment.
[0058]
The magnetic characteristics of electrical steel sheet may be measured by, for
instance, the single sheet tester (SST). Specifically, the magnetic flux density B50 may
5 be obtained by measuring the magnetic flux densities in the unit of T (tesla) in the rolling
direction and in the transverse direction when the steel sheet is excited under the
magnetic field strength of 5000 A/m. In the same way, the saturation magnetic flux
density Bs may be obtained by measuring the magnetic flux densities in the unit of T
(tesla) in the rolling direction and in the transverse direction when the steel sheet is
10 excited under the maximum magnetic field.
[0059]
(Punchability of Electrical Steel Sheet)
In the non oriented electrical steel sheet according to the embodiment, the
alignment degree to {5 5 7}<7 14 5> orientation is made to increase, and thereby, the
15 punching accuracy is improved. For instance, when the circular punching is conducted,
the roundness of the punched piece is improved.
[0060]
Herein, the roundness may be evaluated by the difference between the maximum
radius and the minimum radius of the circular punched piece. For instance, the circular
20 piece with the radius of 200 mm is punched, the maximum radius and the minimum
radius of the punched piece is measured, and then, the difference may be evaluated.
[0061]
In the embodiment, the roundness is preferably 45 |im or less, and more
preferably 40 |im or less. On the other hand, the lower limit of the roundness is not
25 particularly limited. However, since it is substantially difficult to control the roundness

21 to be less than 5 |im, the lower limit thereof may be 5 |im.
[0062]
As explained above, in the embodiment, the alignment degree to {5 5 7}<7 14
5> orientation in the central area along the thickness direction is made to increase as
5 compared with the conventional steel sheet, and thereby, the punchability is improved.
The mechanism for improving the punchability is considered as follows.
[0063]
The {5 5 7}<7 14 5> orientation which is controlled in the embodiment is the
orientation relatively close to the {1 1 1 }<1 1 2> orientation. In the {1 1 1} orientation,
10 the hardness anisotropy in the whole circumferential direction is small, and thus, the
deformation where the steel sheet is stretched by punching is substantially equal over the
whole circumferential direction. Therefore, it is considered that, when the alignment
degree to {5 5 7}<7 14 5> orientation is made to increase, the punchability is improved.
[0064]
15 (Other Features of Electrical Steel Sheet)
The thickness of silicon steel sheet may be appropriately adjusted depending on
the intended use and the like, and is not particularly limited. From a production
standpoint, the thickness of silicon steel sheet is preferably 0.10 mm or more, and more
preferably 0.15 mm or more. On the other hand, the thickness of silicon steel sheet is
20 preferably 0.50 mm or less, and more preferably 0.35 mm or less.
[0065]
The non oriented electrical steel sheet according to the embodiment may have an
insulation coating on the surface of silicon steel sheet. The type of insulation coating is
not particularly limited, and may be selected depending on the intended use and the like
25 from the known coating.

22 [0066]
For instance, the insulation coating may be either an organic coating or an
inorganic coating. Examples of the organic coating include: polyamine resins; acrylic
resins; acrylic styrene resins; alkyd resins; polyester resins; silicone resins; fluorocarbon
5 resins; polyolefin resins; styrene resins; vinyl acetate resins; epoxy resins; phenolic
resins; urethane resins; melamine resins; and the like.
[0067]
Examples of the inorganic coating include: phosphate-based coatings; aluminum
phosphate-based coatings; and the like. Moreover, an organic-inorganic composite
10 coating containing the above-mentioned resin is included. The thickness of insulation
coating is not particularly limited, and is preferably 0.05 to 2 |im as an average thickness
per one side.
[0068]
Next, a producing method for the non oriented electrical steel sheet according to
15 the embodiment is explained.
[0069]
Fig. 2 is a flow chart illustrating a producing method for the non oriented
electrical steel sheet according to the embodiment. In the embodiment, the silicon steel
sheet is obtained by casting molten steel with an adjusted composition, by being
20 hot-rolled, by being heat-conservation-treated during cooling after hot rolling, by being
pickled, by being cold-rolled, and then by being final-annealed. Further, the non
oriented electrical steel sheet is obtained by forming the insulation coating on the silicon
steel sheet.
[0070]
25 In the embodiment, the ratio of recrystallized structure and non-recrystallized

23 structure in the steel sheet before cold rolling (fraction of non-recrystallized grains) is
controlled by controlling each process, and then, the alignment degree to {5 5 7}<7 14
5> orientation in the central area along the thickness direction of the silicon steel sheet is
made to increase by controlling cold rolling and final annealing.
5 [0071]
For instance, the fraction of non-recrystallized grains before cold rolling is not
the technical feature which can be controlled by one condition in one process, but is the
technical feature which can be controlled by each condition of each process which is
comprehensively influenced each other. The conditions are steel composition,
10 temperature of hot rolling, reduction of hot rolling, cooling conditions after hot rolling,
and the like.
[0072]
Specifically,
the Si content of steel composition is the factor which influences whether the
15 constituent phase of the steel structure becomes the a phase and/or the y phase at the hot
rolling temperature. When the Si content becomes higher within the range of 0.01 to
3.50%, the fraction of non-recrystallized grains before cold rolling becomes larger.
The Al content of steel composition is the factor which influences whether the
constituent phase of the steel structure becomes the a phase and/or the y phase at the hot
20 rolling temperature. When the Al content becomes higher within the range of 0.001 to
2.500%, the fraction of non-recrystallized grains before cold rolling becomes larger.
The Mn content of steel composition is the factor which influences the amount
of formed MnS influencing the driving force of recrystallization. When the Mn content
becomes higher within the range of 0.01 to 3.00%, the fraction of non-recrystallized
25 grains before cold rolling becomes larger.

24 The temperature of hot rolling, specifically the slab heating temperature before
hot rolling, is the factor which influences whether the constituent phase of the steel
structure becomes the a phase and/or the y phase, and the factor which influences the
deformed structure formed by hot rolling. When the slab heating temperature before
5 hot rolling becomes higher within the range of 1000 to 1300°C, the fraction of
non-recrystallized grains before cold rolling becomes larger.
The temperature of hot rolling, specifically the finish rolling temperature for
final hot rolling, is the factor which influences whether the constituent phase of the steel
structure becomes the a phase and/or the y phase, and the factor which influences the
10 deformed structure formed by hot rolling. When the finish rolling temperature for final
hot rolling becomes higher within the range of 800 to 950°C, the fraction of
non-recrystallized grains before cold rolling becomes smaller.
The reduction of hot rolling is the factor which influences the deformed
structure formed by hot rolling. When the cumulative reduction of hot rolling becomes
15 larger within the range of 98 to 99.5%, the fraction of non-recrystallized grains before
cold rolling becomes smaller.
The cooling conditions after hot rolling, specifically the cooling rate from the
temperature after finishing the hot rolling to the heat conservation temperature for heat
conservation treatment is the factor which influences the recovery and the
20 recrystallization of the deformed structure formed by hot rolling. When the average
cooling rate in the above temperature range becomes faster within the range of 80 to
200 °C/second, the fraction of non-recrystallized grains before cold rolling becomes
larger.
The cooling conditions after hot rolling, specifically the heat conservation
25 temperature for heat conservation treatment is also the factor which influences the

25 recovery and the recrystallization of the deformed structure formed by hot rolling.
When the heat conservation temperature for heat conservation treatment becomes higher
within the range of 700 to 850°C, the fraction of non-recrystallized grains before cold
rolling becomes smaller.
5 The cooling conditions after hot rolling, specifically the heat conservation time
for heat conservation treatment is also the factor which influences the recovery and the
recrystallization of the deformed structure formed by hot rolling. When the heat
conservation time for heat conservation treatment becomes longer within the range of 10
to 180 minutes, the fraction of non-recrystallized grains before cold rolling becomes
10 smaller.
[0073]
In the embodiment, the steel structure is elaborated by purposely,
comprehensively, and inseparably controlling each condition explained above, in order to
control the fraction of non-recrystallized grains before cold rolling to be 1/10 to 1/5 in
15 the microstructure, specifically to be 10 to 20 area%.
[0074]
Next, the steel sheet in which the fraction of non-recrystallized grains before
cold rolling is controlled is subjected to cold rolling and final annealing, in order to
control the {5 5 7}<7 14 5> oriented grains to be preferentially recrystallized.
20 [0075]
For instance, the alignment degree to {5 5 7}<7 14 5> orientation is not the
technical feature which can be controlled by one condition in one process, but is the
technical feature which can be controlled by each condition of each process which is
comprehensively influenced each other. The conditions are the fraction of
25 non-recrystallized grains before cold rolling, reduction of cold rolling, heating rate of

26 final annealing, and the like.
[0076]
Specifically,
the reduction of cold rolling is the factor which influences the deformed
5 structure formed by cold rolling. The deformed structure formed by cold rolling
becomes the base structure where the {5 5 7}<7 14 5> oriented grains are to be
recrystallized. When the cumulative reduction of cold rolling becomes larger within the
range of 80 to 95%, the alignment degree to {5 5 7}<7 14 5> orientation becomes
smaller.
10 The heating rate of final annealing, specifically the heating rate from the heating
start temperature to 750°C is the factor which influences the formation of
recrystallization nucleus of the {5 5 7}<7 14 5> oriented grains. When the average
heating rate in the above temperature range is close to the median in the range of 5 to
50 °C/second, the alignment degree to {5 5 7}<7 14 5> orientation becomes larger.
15 The heating rate of final annealing, specifically the heating rate from 750°C to
the holding temperature for final annealing is the factor which influences the grain
growth of the {5 5 7}<7 14 5> oriented grains. When the average heating rate in the
above temperature range becomes faster within the range of 20 to 100 °C/second, the
alignment degree to {5 5 7}<7 14 5> orientation becomes larger.
20 [0077]
In the embodiment, the steel structure is elaborated by purposely,
comprehensively, and inseparably controlling each condition explained above, in order to
control the alignment degree to{557}<7 145> orientation in the central area along the
thickness direction of the silicon steel sheet to be 12 to 35.
25 [0078]

27 As explained above, the alignment degree to {5 5 7}<7 14 5> orientation is not
the technical feature which can be controlled by one condition in one process. The
alignment degree to {5 5 7}<7 14 5> orientation is the technical feature which can be
elaborated only by controlling the conditions of cold rolling and final annealing in
5 addition to controlling the fraction of non-recrystallized grains before cold rolling.
[0079]
Specifically, the producing method for the non oriented electrical steel sheet
according to the embodiment includes a casting process, a hot rolling process, an heat
conservation process, a pickling process, a cold rolling process, a final annealing process,
10 and a coating formation process, wherein
in the casting process, a slab is cast, the slab including, as a chemical
composition, by mass%,
0.01 to 3.50% of Si,
0.001 to 2.500% of Al,
15 0.01 to 3.00% of Mn,
0.0030% or less of C,
0.180% or less of P,
0.003% or less of S,
0.003% or less of N,
20 0.002% or less of B,
0to0.05%ofSb,
0to0.20%ofSn,
0tol.00%ofCu,
0 to 0.0400% of REM,
25 0 to 0.0400% of Ca,

28 0 to 0.0400% of Mg, and
a balance consisting of Fe and impurities,
in the hot rolling process, a slab heating temperature before hot rolling is 1000
to 1300°C, a finish rolling temperature for final hot rolling is 800 to 950°C, a cumulative
5 reduction of hot rolling is 98 to 99.5%, and an average cooling rate from a temperature
after finishing the hot rolling to a heat conservation temperature for heat conservation
treatment is 80 to 200 °C/second,
in the heat conservation process, the heat conservation temperature is 700 to
850°C and a heat conservation time is 10 to 180 minutes,
10 a fraction of non-recrystallized grains in a steel sheet before the cold rolling
process is controlled to be 10 to 20 area%,
in the cold rolling process, a cumulative reduction of cold rolling is 80 to 95%,
and
in the final annealing process, an average heating rate from a heating start
15 temperature to 750°C is 5 to 50 °C/second, an average heating rate from 750°C to a
holding temperature for final annealing is changed to a heating rate which is faster than
the average heating rate to 750°C and which is within a range of 20 to 100 °C/second,
and the holding temperature for final annealing is a recrystallization temperature or
higher.
20 [0080]
Hereinafter, as the favorable producing method, the processes will be described
in order form the casting process.
[0081]
(Casting Process)
25 In the casting process, the molten steel with predetermined chemical

29 composition may be made by a converter or an electric furnace, and the slab may be
made by using the molten steel. The slab may be made by continuous casting. The
ingot may be made by using the molten steel, and then, the slab may be made by
blooming the ingot. The slab may be made by other methods. The thickness of the
5 slab is not particularly limited. The thickness of the slab may be 150 to 350 mm for
instance. The thickness of the slab is preferably 220 to 280 mm. The slab with the
thickness of 10 to 70 mm which is a so-called thin slab may be used.
[0082]
In the casting process, in order to control the fraction of non-recrystallized
10 grains in the steel sheet before cold rolling to be 10 to 20 area%, the Si content of steel composition is controlled to be within the range of 0.01 to 3.50%, the Al content is controlled to be within the range of 0.001 to 2.500%, and the Mn content is controlled to be within the range of 0.01 to 3.00%. [0083]
15 The Si content is preferably 0.10% or more, more preferably 0.50% or more,
further more preferably more than 2.00%, further more preferably 2.10% or more, and further more preferably 2.30% or more. The Si content is preferably 3.20% or less, and more preferably 3.00% or less. The Al content is preferably 0.010% or more, more preferably 0.050% or more, further more preferably more than 0.50%, and further more
20 preferably 0.60% or more. The Al content is preferably 2.000% or less, and more preferably 1.600% or less. The Mn content is preferably 0.15% or more, more preferably 0.40% or more, further more preferably more than 0.60%, and further more preferably 0.70% or more. The Mn content is preferably 2.50% or less, and more preferably 2.00% or less.
25 [0084]

30 (Hot Rolling Process)
In the hot rolling process, the slab may be hot-rolled by a hot rolling mill. The
hot rolling mill includes, for instance, a rough rolling mill and a final rolling mill which
is arranged downstream of the rough rolling mill. The heated steel piece is rolled by the
5 rough rolling mill and then by the final rolling mill, and thereby, the hot rolled steel sheet
is obtained.
[0085]
In the hot rolling process, in order to control the fraction of non-recrystallized
grains in the steel sheet before cold rolling to be 10 to 20 area%, the slab heating
10 temperature before hot rolling is controlled to be within the range of 1000 to 1300°C, the
finish rolling temperature for final hot rolling is controlled to be within the range of 800
to 950°C, the cumulative reduction of hot rolling is controlled to be within the range of
98 to 99.5%, and the average cooling rate from the temperature after finishing the hot
rolling to the heat conservation temperature for heat conservation treatment is controlled
15 to be within the range of 80 to 200 °C/second.
[0086]
The slab heating temperature is preferably 1100°C or more, and more preferably
1150°C or more. The slab heating temperature is preferably 1250°C or less, and more
preferably 1200°C or less. The finish rolling temperature is preferably 850°C or more.
20 The finish rolling temperature is preferably 900°C or less. The average cooling rate is
preferably 100 °C/second or more, and more preferably 120 °C/second or more. The
average cooling rate is preferably 180 °C/second or less, and more preferably
150 °C/second or less.
[0087]
25 Herein, when the final hot rolling is started, the thickness of the steel sheet is

31 preferably 20 to 100 mm. Moreover, the cumulative reduction of hot rolling is defined
as follows.
Cumulative reduction (%) = (1 - Thickness of steel sheet after hot rolling /
Thickness of steel sheet before hot rolling ) x 100
5 [0088]
(Heat Conservation Process)
In the heat conservation process, the hot rolled steel sheet is
heat-conservation-treated during cooling after hot rolling. In the heat conservation
process, in order to control the fraction of non-recrystallized grains in the steel sheet
10 before cold rolling to be 10 to 20 area%, the heat conservation temperature is controlled
to be within the range of 700 to 850°C and a heat conservation time is controlled to be
within the range of 10 to 180 minutes.
[0089]
The heat conservation temperature is preferably 750°C or more, and more
15 preferably 780°C or more. The heat conservation temperature is preferably 830°C or
less, and more preferably 800°C or less. The heat conservation time is preferably 20
minutes or more, more preferably 30 minutes or more, and further more preferably 40
minutes or more. The heat conservation time is preferably 150 minutes or less, more
preferably 120 minutes or less, and further more preferably 100 minutes or less.
20 [0090]
(Pickling Process)
In the pickling process, the pickling may be conducted in order to remove the
scale formed on the surface of hot rolled steel sheet. The conditions for pickling the hot
rolled steel sheet are not particularly limited, and known conditions may be appropriately
25 applied.

32 [0091]
(Steel Sheet before Cold Rolling Process)
In the embodiment, with respect to the microstructure of the steel sheet which is
after the casting process, the hot rolling process, the heat conservation process, and the
5 pickling process and which is before the cold rolling process, the fraction of
non-recrystallized grains in the microstructure is controlled to be 10 to 20 area%.
[0092]
One of main orientation of the conventional non oriented electrical steel sheet is
the {111 }<1 1 2> orientation. In general, the microstructure of the steel sheet before
10 cold rolling is made to be entirely recrystallized, the strain is accumulated into the
microstructure by cold rolling, the recrystallization nucleus are made to be formed and
grown from grain boundaries during final rolling, and thereby, the grains having the
above orientation are formed. On the other hand, in the embodiment, the predetermined
amount of the non-recrystallized grains is made to remain in the microstructure of the
15 steel sheet before cold rolling, the conditions of cold rolling and the conditions of final
annealing are favorably controlled, and thereby, the grains having the {5 5 7}<7 14 5>
orientation are purposely formed.
[0093]
When the above fraction of non-recrystallized grains does not satisfy 10 to 20
20 area%, the alignment degree to {5 5 7}<7 14 5> orientation is difficult to be eventually
controlled. Moreover, when the excessive amount of the non-recrystallized grains is
included in the microstructure of the steel sheet before cold rolling, the grains having the
{4 11 }<1 4 8> orientation which are effective for improving the magnetic characteristics
are difficult to be formed in the microstructure after final annealing. Thus, in order to
25 favorably improve both the magnetic characteristics and the punchability, it is optimal to

33 control the fraction of non-recrystallized grains in the steel sheet before the cold rolling
process to be 10 to 20 area%.
[0094]
In conventional technique, the hot rolled steel sheet after hot rolling is cooled to
5 near room temperature, and thereafter, the hot rolled steel sheet annealing is conducted
under conditions such that the holding temperature is 800 to 1050°C and the holding time
is 1 minutes or less by reheating the steel sheet. However, in case of the hot rolled steel
sheet annealing, it is difficult to elaborate the recrystallized structure and the
non-recrystallized structure which satisfy the above ratio in the microstructure of the
10 steel sheet before cold rolling.
[0095]
In the embodiment, in order to control the fraction of non-recrystallized grains
in the steel sheet before cold rolling, the steel sheet is subjected to the above heat
conservation treatment during cooling after hot rolling. Moreover, the steel sheet after
15 heat conservation treatment is cooled to near room temperature, and thereafter, the hot
rolled steel sheet annealing is not conducted. As a result, the fraction of
non-recrystallized grains in the steel sheet before cold rolling is favorably controlled, and
thus, it is possible to eventually increase the alignment degree to {5 5 7}<7 14 5>
orientation in the central area along the thickness direction of the steel sheet.
20 [0096]
The fraction of non-recrystallized grains in the steel sheet before cold rolling
may be measured by the following method. A sample with approximately 25 mm x 25
mm is cut out from the steel sheet before cold rolling, the sheet surface of the sample is
mechanical-polished, and thereby, the thickness of the steel sheet is reduced to 1/2. The
25 polished surface is chemical-polished or electrolytic-polished, and thereby, the

34 measurement sample without strain is obtained.
[0097]
The fraction of non-recrystallized grains in the observed visual field may be
obtained from KAM value (Kernel Average Misorientation) by conducting EBSD
5 (Electron Back Scattering Diffraction) for the measurement sample. For instance, the
grain whose KAM value is 2.0 or more is regarded as the non-recrystallized grains in the
observed visual field. The EBSD measurements may be conducted on ten places or
more while changing the observed visual field, and the total area of the observed visual
fields may be 1000000 |im2 or more.
10 [0098]
As explained above, in the embodiment, it is preferable that the hot rolled steel
sheet annealing is not conducted between the hot rolling process and the cold rolling
process. Specifically, in the embodiment, it is preferable that the hot rolling process, the
heat conservation process, the pickling process, and the cold rolling process are
15 continuous processes. In other words, it is preferable that the steel sheet after the hot
rolling process is subjected to the heat conservation treatment, the steel sheet after the
heat conservation process is subjected to the pickling, and the steel sheet after the
pickling process is subjected to the cold rolling.
[0099]
20 (Cold Rolling Process)
In the cold rolling process, the steel sheet in which the fraction of
non-recrystallized grains is controlled to be 10 to 20 area% is cold-rolled. In the cold
rolling process, in order to control the alignment degree to {5 5 7}<7 14 5> orientation to
be 12 to 35 after final annealing, the cumulative reduction of cold rolling is controlled to
25 be within the range of 80 to 95%. The cumulative reduction is preferably 83% or more,

35 and more preferably 85% or more.
[0100]
The cumulative reduction of cold rolling is defined as follows.
Cumulative reduction (%) = (1 - Thickness of steel sheet after cold rolling /
5 Thickness of steel sheet before cold rolling ) x 100
[0101]
(Final Annealing Process)
In the final annealing process, the cold rolled steel sheet is final-annealed. In
the final annealing process, in order to control the alignment degree to {5 5 7}<7 14 5>
10 orientation to be 12 to 35 after final annealing, the average heating rate from the heating
start temperature to 750°C is controlled to be within the range of 5 to 50 °C/second, the
average heating rate from 750°C to the holding temperature for final annealing is
changed to the heating rate which is faster than the average heating rate to 750°C and is
controlled to be within the range of 20 to 100 °C/second, and the holding temperature for
15 final annealing is controlled to be the recrystallization temperature or higher.
[0102]
The average heating rate to 750°C is preferably 10 °C/second or more, and more
preferably 20 °C/second or more. The average heating rate to 750°C is preferably
40 °C/second or less, and more preferably 30 °C/second or less. The average heating
20 rate from 750°C is preferably 30 °C/second or more, and more preferably 40 °C/second
or more. The average heating rate from 750°C is preferably 80 °C/second or less, and
more preferably 60 °C/second or less.
[0103]
The holding temperature for final annealing is preferably 800 to 1200°C. The
25 holding temperature is preferably 850°C or more. The holding time is preferably 5 to

36 120 seconds. The holding time is preferably 10 seconds or more, and more preferably
20 seconds or more.
[0104]
The alignment degree to {5 5 7}<7 14 5> orientation in the central area along
5 the thickness direction of the steel sheet (silicon steel sheet) is controlled to be 12 to 35
through final annealing.
[0105]
(Coating Formation Process)
In the coating formation process, the insulation coating is formed for the silicon
10 steel sheet after final annealing. For instance, the insulation coating may be either the
organic coating or the inorganic coating. The forming conditions of insulation coating
may be the same as those of the insulation coating of conventional non oriented electrical
steel sheet.
[0106]
15 The non oriented electrical steel sheet in which the alignment degree to {5 5
7}<7 14 5> orientation is favorably controlled by the above processes is suitable as the
magnetic material such as rotating machines, small and medium-size transformers, and
electrical components, and especially, is suitable as the magnetic material for the split
core of motor.
20 [0107]
Hereinafter, a case where the non oriented electrical steel sheet according to the
embodiment is used for the split core of motor is explained.
[0108]
Fig. 3 is an illustration showing an instance of the split core of motor. As
25 shown in Fig. 3, the motor core 100 includes the punched piece 11 and the lamination 13

37 in which the punched pieces 11 are laminated and unified. The punched piece 11 is
prepared by punching the non oriented electrical steel sheet. The punched piece 11
includes the yoke 17 with arc-shape and the teeth 15 which protrudes inward in the radial
direction from the inner peripheral surface of the yoke 17. The punched piece 11 is
5 arranged in an annular shape, and thereby, the motor core 100 is configured.
[0109]
The shape, the number arranged in the annular shape, the number of layers, and
the like of the punched piece 11 may be designed according to the purpose.
10 Examples
[0110]
Hereinafter, the effects of an aspect of the present invention are described in detail with reference to the following examples. However, the condition in the examples is an example condition employed to confirm the operability and the effects of 15 the present invention, so that the present invention is not limited to the example condition. The present invention can employ various types of conditions as long as the conditions do not depart from the scope of the present invention and can achieve the object of the present invention. [0111] 20
The slab with the adjusted composition was cast, and then, the silicon steel sheet was produced by controlling the production conditions in each process. The chemical compositions of the silicon steel sheets are shown in Tables 1 and 2, and the production conditions are shown in Tables 3 to 8. In the above production, the hot rolling and the 25 heat conservation treatment were conducted under the conditions shown in Tables 3 to 5,

38 the cooling was conducted to room temperature, and then, the pickling was conducted.
Herein, the specimen described as "hot rolled steel sheet annealing" in the "heat
conservation treatment" column in the tables was cooled to room temperature without the
heat conservation treatment during cooling after hot rolling. Thereafter, the hot rolled
5 steel sheet annealing was conducted in the atmosphere of 100% nitrogen at 800°C for 60
seconds, the cooling was conducted to room temperature, and then, the pickling was
conducted.
[0112]
The measurement result of the fraction of non-recrystallized grains in the
10 microstructure of the steel sheet which was after the casting process, the hot rolling
process, the heat conservation process, and the pickling process and which was before the cold rolling process are shown in Tables 3 to 5. Herein, the fraction of non-recrystallized grains was measured on the basis of the above method. [0113]
15 For the steel sheets whose fraction of non-recrystallized grains was measured,
the cold rolling and the final annealing were conducted under conditions shown in Tables 6 to 8. In the final annealing, the holding temperature was 800 to 1100°C which was equal to or higher than the recrystallization temperature, and the holding time was 30 seconds. Moreover, for the silicon steel sheet after final annealing, the phosphate based
20 insulation coating with the average thickness of 1 |im was formed. Herein, with respect to the "final annealing" column in tables, the "heating rate A" expresses the average heating rate from the heating start temperature to 750°C, the "heating rate B" expresses the average heating rate from 750°C to the holding temperature for final annealing, and the "control of heating rates" expresses the relationship of the heating rate A and the
25 heating rate B.

39 [0114]
The measurement result of the alignment degree to {5 5 7}<7 14 5> orientation
in the central area along the thickness direction of the silicon steel sheet of the produced
non oriented electrical steel sheet are shown as "alignment degree of texture" in Tables 6
5 to 8. Herein, the alignment degree to{557}<7 145> orientation was measured on the
basis of the above method.
[0115]
The chemical compositions of the silicon steel sheets are shown in Tables 1 and
2, and the production conditions and the production results are shown in Tables 3 to 8.
10 Herein, the chemical compositions of the silicon steel sheets were substantially the same
as those of the slabs. In the tables,"-" with respect to the chemical composition of
silicon steel sheet indicates that no alloying element was intentionally added or that the
content was less than detection limit. In the tables, the underlined value indicates out of
the range of the present invention.
15 [0116]
For the produced non oriented electrical steel sheet, the magnetic flux density
was evaluated as the magnetic characteristics, and the roundness of the circular punched
piece was evaluated as the punchability. The magnetic flux density and the roundness
were measured on the basis of the above method. When the ratio B50 / Bs was 0.82 or
20 more, the magnetic characteristics was judged to as acceptable. Moreover, when the
roundness of the circular punched piece was 45 |im or less, the punchability was judged
to as acceptable.
[0117]
The evaluation results of the magnetic characteristics and the punchability are
25 shown in Tables 6 to 8. In the inventive examples of Nos. Bl to B22, the chemical

40 composition and the texture of the silicon steel sheet were favorably controlled, and thus,
the magnetic characteristics and the punchability were excellent as the non oriented
electrical steel sheet.
[0118]
5 On the other hand, in the comparative examples of Nos. bl to b44, at least one
of the chemical composition and the texture of the silicon steel sheet was not favorably controlled, and thus, at least one of the magnetic characteristics and the punchability was not satisfied as the non oriented electrical steel sheet.
[0119]
10 Fig. 4 is a diagram showing a relation of the alignment degree to {5 5 7}<7 14
5> orientation and roundness. Fig. 4 is the diagram showing the relation of the alignment degree to{557}<7 145> orientation and the roundness on the basis of the inventive examples of Nos. Bl to B22 and the comparative examples of Nos. bl to b44. Fig. 4 shows that the roundness decreases with increase the alignment degree to {5 5 15 7} <7 14 5> orientation.
[0120]
[Table 1]

TABLE

1

STEEL No. PRODUCTION CONDITIONS AND PRODUCTION RESULTS

CHEMICAL COMPOSITION OF SILICON STEE L SHEET (IN UNI1 S OFMASS%, BALA

C Si Mn Al P S N B Sb
A1 0.0029 2.953 0.209 0.490 0.034 0.0017 0.0023 0.0011 -
A2 0.0026 0.011 0.156 0.114 0.087 0.0011 0.0026 0.0013 -
A3 0.0027 3.448 0.271 0.904 0.122 0.0018 0.0025 0.0011 -
A4 0.0025 0.216 0.011 0.534 0.147 0.0025 0.0022 0.0015 -
A5 0.0026 2.534 2.998 1.309 0.138 0.0022 0.0021 0.0014 -
A6 0.0028 0.826 0.124 0.001 0.112 0.0019 0.0029 0.0016 -
A7 0.0024 2.889 0.253 2.447 0.147 0.0009 0.0017 0.0017 -
A8 0.0021 3.022 0.227 1.453 0.18 0.0008 0.0011 0.0012 -
A9 0.0028 3.029 2.112 0.589 0.044 0.0029 0.0018 0.0009 -
A10 0.0021 1.876 0.576 0.239 0.087 0.0017 0.0029 0.0008 -
A11 0.0017 2.448 1.006 0.875 0.049 0.0019 0.0019 0.0018 -
A12 0.0015 1.189 0.227 0.284 0.093 0.0022 0.0022 0.0008 0.0479
A13 0.0009 2.889 1.087 0.034 0.153 0.0026 0.0025 0.0011 -
A14 0.0008 1.665 0.228 0.038 0.034 0.0016 0.0023 0.0014 0.0231
A15 0.0018 2.238 1.084 0.699 0.139 0.0022 0.0011 0.0004 0.0119
A16 0.0025 2.673 0.093 0.781 0.011 0.0018 0.0018 0.0007 0.0161
A17 0.0014 1.452 1.987 0.117 0.026 0.0022 0.0026 0.0017 0.0229
A18 0.0020 2.048 0.210 0.321 0.025 0.0012 0.0025 0.0012 -
A19 0.0021 3.019 0.208 0.312 0.023 0.0025 0.0023 0.0014 -
A20 0.0023 3.022 0.215 0.297 0.033 0.0026 0.0020 0.0011 -
A21 0.0020 3.031 0.221 0.284 0.029 0.0026 0.0018 0.0013 -
A22 0.0013 0.498 0.151 0.284 0.069 0.0011 0.0014 0.0010 -

TABLE

2

STEEL No. PRODUCTION CONDITIONS AND PRODUCTION RESULTS

CHEMICA L COMPOSITION 0 SILICON STEEL SHEET (IN UNITS 0 FMASS%, BALANCE C0NS

C Si Mn Al P S N B Sb Sn
a1 0.0055 3.224 0.251 0.451 0.115 0.0029 0.0025 0.002 0.0039 0.1
a2 0.0022 0.004 0.272 0.185 0.097 0.0009 0.0022 0.0016 0.0021 0.1
a3 0.0026 4.106 0.114 1.003 0.152 0.0023 0.0028 0.0019 0.0031 0.0
a4 0.0013 2.167 0.002 0.509 0.116 0.0018 0.0027 0.0018 0.0019 0.0
a5 0.0006 1.459 3.504 0.202 0.139 0.0014 0.0021 0.0009 0.0025 0.1
a6 0.0009 2.928 0.373 0.0004 0.082 0.0027 0.0023 0.0017 0.0037 0.0
a7 0.0015 2.201 0.684 2.803 0.166 0.0011 0.0019 0.0016 0.0028 0.0
a8 0.0014 1.806 0.785 0.616 0.292 0.0021 0.0011 0.0017 0.0033 0.0
a9 0.0011 2.717 1.529 1.225 0.087 0.0039 0.0021 0.0016 0.0022 0.1
a10 0.0009 1.512 0.901 0.305 0.123 0.0016 0.0051 0.0006 0.0035 0.1
a11 0.0008 2.599 2.437 0.904 0.145 0.0025 0.0029 0.003 0.0018 0.0
a12 0.0025 3.342 2.896 2.456 0.093 0.0009 0.0019 0.0009 - -
a13 0.0029 0.013 0.027 0.004 0.098 0.0008 0.0017 0.0010 - -
a14 0.0024 3.126 1.545 1.243 0.091 0.0010 0.0019 0.0011 - -
a16 0.0021 2.044 2.951 1.124 0.095 0.0008 0.0020 0.0008 - -
a17 0.0023 2.102 1.122 0.005 0.095 0.0011 0.0018 0.0009 - -
a18 0.0011 0.502 0.169 0.311 0.073 0.0009 0.0018 0.0008 - 0.0
a19 0.0012 0.499 0.172 0.308 0.074 0.0008 0.0021 0.0007 - 0.0
a20 0.0021 2.242 1.104 0.708 0.145 0.0019 0.0009 0.0006 - -

TABLE 3

TEST No. STEEL No. PRODUCTION CONDITIONS AND PRODUCTION RESULTS

CASTING HOT ROLLING HEAT CONSERVATION TREATMENT FRACTION
OFNON-
RECRYSTALLIZED
GRAINS IN STEEL
SHEET BEFORE
COLD ROLLING
AREA%

Si
MASS% Mn
MASS% Al
MASS% SLAB
HEATING
TEMPERATURE
°C CUMULATIVE REDUCTION
% FINAL ROLLING HEAT CONSERVATION TEMPERATURE
°C HEAT
CONSERVATION
TIME
MINUTES

FINISH TEMPERATURE
°C COOLING RATE
°C/SECOND

B1 A1 2.953 0.209 0.490 1100 98.5 880 120 800 30 17
B2 A2 0.011 0.156 0.114 1200 98.0 810 180 780 15 18
B3 A3 3.448 0.271 0.904 1150 98.5 890 100 750 30 13
B4 A4 0.216 0.011 0.534 1200 98.0 830 170 780 20 14
B5 A5 2.534 2.998 1.309 1150 98.5 950 130 705 60 19
B6 A6 0.826 0.124 0.001 1230 98.5 850 120 780 15 17
B7 A7 2.889 0.253 2.447 1150 98.5 900 120 780 70 11
B8 A8 3.022 0.227 1.453 1150 99.0 950 130 845 120 18
B9 A9 3.029 2.112 0.589 1080 98.5 880 130 780 80 18
B10 A10 1.876 0.576 0.239 1180 98.5 940 130 780 10 11
B11 A11 2.448 1.006 0.875 1150 98.5 900 120 750 80 18
B12 A12 1.189 0.227 0.284 1175 99.0 930 130 790 180 18
B13 A13 2.889 1.087 0.034 1150 98.5 900 110 780 80 17
B14 A14 1.665 0.228 0.038 1150 99.0 900 130 810 50 20
B15 A15 2.238 1.084 0.699 1180 99.0 890 140 770 70 18
B16 A16 2.673 0.093 0.781 1150 98.5 900 130 800 50 15
B17 A17 1.452 1.987 0.117 1130 98.5 880 120 780 40 15
B18 A18 2.048 0.210 0.321 1200 99.0 880 120 780 15 16
B19 A19 3.019 0.208 0.312 1150 98.5 900 130 790 30 16
B20 A20 3.022 0.215 0.297 1170 98.5 910 150 780 50 14
B21 A21 3.031 0.221 0.284 1150 99.0 890 130 800 70 15
B22 A22 0.498 0.151 0.284 1280 98.5 820 180 710 15 16
[0123] [Table 4]

TABLE

4

TEST No. STEEL No. PRODUCTION CONDITIONS AND PRODUCTION RESULTS

CASTING HOT ROLLING

Si
MASS% Mn
MASS°/o Al
MASS% SLAB
HEATING
TEMPERATURE
°C CUMULATIVE REDUCTION
% FINAL ROLLIN

FINISH TEMPERATURE
°C COO RA
°C/S

b1 a1 3.224 0.251 0.451 1160 98.5 950 1
b2 a2 0.004 0.272 0.185 1150 98.5 900 1
b3 a3 4.106 0.114 1.003 1150 98.5 900 1
b4 a4 2.167 0.002 0.509 1150 98.5 900 1
b5 a5 1.459 3.504 0.202 1150 98.5 900 1
b6 a6 2.928 0.373 0.0004 1150 98.5 900 1
b7 a7 2.201 0.684 2.803 1150 98.5 900 1
b8 a8 1.806 0.785 0.616 1180 98.5 890 7
b9 a9 2.717 1.529 1.225 1150 98.5 900 1
b10 a10 1.512 0.901 0.305 980 98.5 900 1
b11 a11 2.599 2.437 0.904 1175 98.5 900 1
b12 a12 3.342 2.896 2.456 1150 98.5 900 1
b13 a13 0.013 0.027 0.004 1150 98.5 900 1
b14 a14 3.126 1.545 1.243 1280 98.5 900 1
b16 a16 2.044 2.951 1.124 1150 98.5 810 1
b17 a17 2.102 1.122 0.005 1030 98.5 900 1
b18 a18 0.502 0.169 0.311 1150 99.5 890 8
b19 a19 0.499 0.172 0.308 1150 99.0 940 8
b20 a20 2.242 1.104 0.708 1270 98.5 805 1

45
TABLE 5

TEST No. STEEL No. PRODUCTION CONDITIONS AND PRODUCTION RESULTS

CASTING HOT ROLLING HEAT CONSERVATION TREATMENT FRACTION
OFNON-
RECRYSTALLIZED
GRAINS IN STEEL
SHEET BEFORE
COLD ROLLING
AREA%

Si MASS% Mn
MASS% Al
MASS% SLAB
HEATING
TEMPERATURE
°C CUMULATIVE REDUCTION
% FINAL ROLLING HEAT CONSERVATION TEMPERATURE
°C HEAT
CONSERVATION
TIME
MINUTES

FINISH TEMPERATURE
°C COOLING RATE
°C/SECOND

b21 a20 2.242 1.104 0.708 1045 99.5 900 130 780 170 8
b22 a20 2.242 1.104 0.708 1150 98.0 810 190 780 80 23
b23 a20 2.242 1.104 0.708 1150 98.5 900 90 830 170 6
b24 a20 2.242 1.104 0.708 980 98.5 900 130 780 80 8
b25 a20 2.242 1.104 0.708 1320 98.5 900 130 780 80 22
b26 a20 2.242 1.104 0.708 1150 97.0 900 130 780 80 23
b27 a20 2.242 1.104 0.708 1150 99.8 900 130 780 80 9
b28 a20 2.242 1.104 0.708 1150 98.5 780 130 780 80 22
b29 a20 2.242 1.104 0.708 1150 98.5 970 130 780 80 8
b30 a20 2.242 1.104 0.708 1150 98.5 900 75 780 80 9
b31 a20 2.242 1.104 0.708 1150 98.5 900 210 780 80 21
b32 a20 2.242 1.104 0.708 1150 98.5 900 130 680 80 22
b33 a20 2.242 1.104 0.708 1150 98.5 900 130 870 80 8
b34 a20 2.242 1.104 0.708 1150 98.5 900 130 780 8 23
b35 a20 2.242 1.104 0.708 1150 98.5 900 130 780 185 9
b36 a20 2.242 1.104 0.708 1150 98.5 900 130 780 80 15
b37 a20 2.242 1.104 0.708 1150 98.5 900 130 780 80 15
b38 a20 2.242 1.104 0.708 1150 98.5 900 130 780 80 15
b39 a20 2.242 1.104 0.708 1150 98.5 900 130 780 80 15
b40 a20 2.242 1.104 0.708 1150 98.5 900 130 780 80 15
b41 a20 2.242 1.104 0.708 1150 98.5 900 130 780 80 15
b42 a20 2.242 1.104 0.708 1150 98.5 900 130 780 80 15
b43 a20 2.242 1.104 0.708 1150 98.5 900 130 780 80 15
b44 a20 2.242 1.104 0.708 1150 98.5 900 130 HOT ROLL SHEET AN ED STEEL NEALING 0
[0125] [Table 6]

TABLE

6

TEST No. STEEL No. PRODUCTION CONDITIONS AND PRODUCTION RESULTS EVALUATION R

COLD
ROLLING
CUMULATIVE
REDUCTION
% FINAL ANNEAL I NG ALIGNMENT DEGREE OF TEXTURE MAGNETIC FLU

HEATING RATE A
°C/SECOND HEATING RATEB
°C/SECOND CONTROL
OF
HEATING
RATES
B50
T T

B1 A1 88.5 30 40 good 18 1.708 2.03
B2 A2 88.0 10 30 good 15 1.698 2.04
B3 A3 88.0 25 30 good 13 1.609 1.96
B4 A4 87.5 40 60 good 14 1.654 1.99
B5 A5 89.0 20 30 good 15 1.596 1.92
B6 A6 88.0 25 40 good 19 1.789 2.12
B7 A7 88.5 20 35 good 12 1.688 2.03
B8 A8 88.0 50 80 good 16 1.614 1.94
B9 A9 94.0 25 30 good 16 1.715 2.04
B10 A10 88.0 40 50 good 12 1.728 2.06
B11 A11 87.0 25 30 good 17 1.708 2.05
B12 A12 88.0 20 35 good 20 1.725 2.09
B13 A13 81.0 25 30 good 14 1.719 2.07
B14 A14 90.0 35 55 good 16 1.730 2.08
B15 A15 88.0 25 30 good 20 1.725 2.10
B16 A16 88.5 25 30 good 24 1.716 2.04
B17 A17 88.5 45 55 good 24 1.720 2.02
B18 A18 83.0 25 40 good 19 1.725 2.00
B19 A19 85.0 20 35 good 21 1.738 2.06
B20 A20 88.0 25 30 good 20 1.721 2.00
B21 A21 87.5 30 35 good 21 1.745 2.02
B22 A22 83.0 35 60 good 24 1.718 2.07

TABLE

7

TEST No. STEEL No. PRODUCTIO W CONDITIONS AND PRODUCTION RESU .TS EVALUATION RESULTS

COLD
ROLLING
CUMULATIVE
REDUCTION
% FINAL A NNEALING ALIGNMENT DEGREE OF
TEXTURE MAGNETIC FLUX DENS

HEATING RATE A
°C/SECOND HEATING RATEB
°C/SECOND CONTROL
OF
HEATING
RATES
B50
T Bs
T

b1 a1 88.0 25 30 good 9 1.629 2.001
b2 a2 88.0 25 30 good 8 1.601 1.969
b3 a3 88.0 25 30 good 11 1.571 1.956
b4 a4 88.0 25 30 good 8 1.636 2.042
b5 a5 88.0 25 30 good 9 1.625 2.057
b6 a6 88.0 25 30 good 11 1.602 2.003
b7 a7 88.0 25 30 good 7 1.573 1.942
b8 a8 88.0 25 30 good 11 1.624 2.035
b9 a9 88.0 25 30 good 6 1.591 1.964
b10 a10 88.0 25 30 good 10 1.605 2.006
b11 a11 88.0 25 30 good 6 1.570 1.953
b12 a12 88.0 25 30 good 9 1.609 2.037
b13 a13 88.0 25 30 good 8 1.601 2.001
b14 a14 88.0 25 30 good 10 1.603 2.029
b16 a16 88.0 25 30 good 9 1.610 2.038
b17 a17 88.0 25 30 good 8 1.605 2.006
b18 a18 88.0 25 30 good 8 1.609 2.037
b19 a19 88.0 25 30 good 9 1.604 2.030
b20 a20 88.0 25 30 good 10 1.606 2.008

48

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Industrial Applicability
[0128]
According to the above aspects of the present invention, it is possible to provide the non oriented electrical steel sheet excellent in both the punchability and the magnetic characteristics in two directions of the rolling direction and the transverse direction for the split core, and the method for producing thereof. Accordingly, the present invention has significant industrial applicability.

49
Reference Signs List [0129]
I NON ORIENTED ELECTRICAL STEEL SHEET
5 3 SILICON STEEL SHEET (BASE STEEL SHEET)
5 INSULATION COATING
II PUNCHED PIECE
13 LAMINATION
15 TEETH
10 17 YOKE
100 MOTOR CORE

WE CLAIMS

1.A non oriented electrical steel sheet comprising a silicon steel sheet and an
5 insulation coating, characterized in that
the silicon steel sheet contains, as a chemical composition, by mass%,
0.01 to 3.50% of Si,
0.001 to 2.500% of Al,
0.01 to 3.00% of Mn,
10 0.0030% or less of C,
0.180% or less of P,
0.003% or less of S,
0.003% or less of N,
0.002% or less of B,
15 0to0.05%ofSb,
0to0.20%ofSn,
0tol.00%ofCu,
0 to 0.0400% of REM,
0 to 0.0400% of Ca,
20 0 to 0.0400% of Mg, and
a balance consisting of Fe and impurities, and
an alignment degree to{557}<7 145> orientation in a central area along a thickness direction of the silicon steel sheet is 12 to 35.
25 2. The non oriented electrical steel sheet according to claim 1,

51 wherein the silicon steel sheet contains, as the chemical composition, by mass%,
at least one selected from a group consisting of
0.001 to 0.05% of Sb,
0.01 to 0.20% of Sn,
5 0.10 to 1.00% of Cu,
0.0005 to 0.0400% of REM,
0.0005 to 0.0400% of Ca, and
0.0005 to 0.0400% of Mg.
10 3. The non oriented electrical steel sheet according to claim 1 or 2,
wherein the alignment degree to {5 5 7}<7 14 5> orientation is 18 to 35.
4. A method for producing the non oriented electrical steel sheet according to any
one of claims 1 to 3, the method comprising a casting process, a hot rolling process, an 15 heat conservation process, a pickling process, a cold rolling process, a final annealing process, and a coating formation process, wherein
in the casting process, a slab is cast, the slab including, as a chemical composition, by mass%,
0.01 to 3.50% of Si,
20 0.001 to 2.500% of Al,
0.01 to 3.00% of Mn,
0.0030% or less of C,
0.180% or less of P,
0.003% or less of S,
25 0.003% or less of N,

52 0.002% or less of B,
0to0.05%ofSb,
0to0.20%ofSn,
0tol.00%ofCu,
5 0 to 0.0400% of REM,
0 to 0.0400% of Ca,
0 to 0.0400% of Mg, and
a balance consisting of Fe and impurities,
in the hot rolling process, a slab heating temperature before hot rolling is 1000
10 to 1300°C, a finish rolling temperature for final hot rolling is 800 to 950°C, a cumulative
reduction of hot rolling is 98 to 99.5%, and an average cooling rate from a temperature
after finishing the hot rolling to a heat conservation temperature for heat conservation
treatment is 80 to 200 °C/second,
in the heat conservation process, the heat conservation temperature is 700 to
15 850°C and a heat conservation time is 10 to 180 minutes,
a fraction of non-recrystallized grains in a steel sheet before the cold rolling
process is controlled to be 10 to 20 area%,
in the cold rolling process, a cumulative reduction of cold rolling is 80 to 95%,
and
20 in the final annealing process, an average heating rate from a heating start
temperature to 750°C is 5 to 50 °C/second, an average heating rate from 750°C to a
holding temperature for final annealing is changed to a heating rate which is faster than
the average heating rate to 750°C and which is within a range of 20 to 100 °C/second,
and the holding temperature for final annealing is a recrystallization temperature or
25 higher.