DESCRIPTION
TITLE OF INVENTION: MANUFACTURING METHOD OF NONORIENTED
ELECTRICAL STEEL SHEET
TECHNICAL FIELD
[0001] The present invention relates to a
manufacturing method of a non-oriented electrical
steel sheet suitable for an iron core of an electric
equipment.
BACKGROUND ART
[0002] In recent years, in fields of rotary
machines, medium or small sized transformers,
electrical components and the like, which use nonoriented
electrical steel sheets as materials of
their iron cores, a demand for realization of highefficiency
and miniaturization is increasing more and
more, in the movement of global environmental
conservation typified by the worldwide power and
energy saving and CO2 reduction and the like. Under
such a social environment, an improvement in
performance of the non-oriented electrical steel
sheet is of course a pressing issue.
[0003] Further, according to the usage, favorable
magnetic properties in a rolling direction are
sometimes required for a non-oriented electrical
steel sheet. For example, a non-oriented electrical
steel sheet used for a divided iron core among iron
cores of rotary machines, and a non-oriented
electrical steel sheet used for iron cores of medium
or small sized transformers, are sometimes required
to improve magnetic properties in a rolling
direction. In these iron cores, magnetic fluxes
mainly flow in orthogonal two directions. Further,
it is often the case that the rolling direction of
the non-oriented electrical steel sheet is set to one
direction, out of these two directions, in which an
influence of the flow of the magnetic flux is
particularly large.
[0004] Accordingly, various techniques have been
conventionally proposed for the purpose of improving
the magnetic properties of the non-oriented
electrical steel sheet.
[0005] For example, a technique of increasing
contents of Si and A1 for the purpose of reducing an
iron loss has been proposed. For instance, Patent
Literature 1 describes a non-oriented electrical
steel sheet in which an A1 content is increased while
keeping a relatively low Si content for the purpose
of improving workability during performing coldrolling.
A technique in which not only the increase
in contents of Si and/or A1 and the like but also the
reduction in contents of C, S, N and the like is
realized, has also been proposed. Techniques of
reducing an iron loss by making impurities harmless
through chemical treatment such as an addition of Ca
(Patent Literature 2 ) , and an addition of REM (Patent
Literature 3 ) , have also been proposed. Further,
Patent Literature 4 describes a technique regarding a
condition of finish annealing.
[0006] For example, a technique regarding an
improvement in magnetic flux density has also been
proposed. For instance, Patent Literature 5
describes a technique regarding a condition of hotrolled
sheet annealing and a condition of coldrolling.
Further, Patent Literature 6 describes a
technique regarding an addition of alloying elements
of Sn, Cu and the like.
[0007] However, with the conventional techniques, it
is difficult to sufficiently improve the magnetic
properties in the rolling direction of the nonoriented
electrical steel sheet. Further, with the
technique in which the contents of Si and A1 are
increased for the purpose of reducing the iron loss,
a saturation magnetic flux density becomes low. In
particular, A1 easily reduces the saturation magnetic
flux density, when compared to Si, so that with the
technique described in Patent Literature 1, the
saturation magnetic flux density becomes extremely
low. Such a technique in which the saturation
magnetic flux density becomes low, is absolutely
inappropriate for the miniaturization of electric
equipments.
CITATION LIST
PATENT LITERATURE
[0008] Patent Literature 1: Japanese Laid-open
Patent Publication No. 07-228953
Patent Literature 2: Japanese Laid-open Patent
Publication No. 03-126845
Patent Literature 3: Japanese Laid-open Patent
Publication No. 2006-124809
Patent Literature 4: Japanese Laid-open Patent
Publication No. 61-231120
Patent Literature 5: Japanese Laid-open Patent
Publication No. 2004-197217
Patent Literature 6: Japanese Laid-open Patent
Publication No. 05-140648
Patent Literature 7: Japanese Laid-open Patent
Publication No. 52-129612
Patent Literature 8: Japanese Laid-open Patent
Publication No. 53-66816
Patent Literature 9: Japanese Laid-open Patent
Publication No. 2001-172718
SUMMARY OF INVENTION
TECHNICAL PROBLEM
[0009] The present invention has an object to
provide a manufacturing method of a non-oriented
electrical steel sheet capable of improving magnetic
properties in a rolling direction.
SOLUTION TO PROBLEM
[0010] The present inventors repeatedly conducted
earnest studies from a point of view in which
magnetic properties in a rolling direction in a nonoriented
electrical steel sheet are improved by
changing conditions of contents of respective
components, treatment before cold-rolling, the number
of times of the cold-rolling, a rolling reduction in
the cold-rolling and the like.
[0011] As a result, although details will be
described later, the present inventors found out that
it is possible to obtain an effect of significantly
improving the magnetic properties in the rolling
direction, by providing appropriate contents of Si,
Al, Mn and the like, an appropriate finish
temperature in hot-rolling, an appropriate number of
times of cold-rolling, and an appropriate rolling
reduction in the second cold-rolling. Further, the
present inventors came to the following manufacturing
method of a non-oriented electrical steel sheet.
[0012] (1) A manufacturing method of a non-oriented
electrical steel sheet, including:
performing hot-rolling of a steel material so as
to form a steel strip, the steel material containing,
in mass%:
Si: not less than 0.1% nor more than 4.0%;
Al: not less than 0.1% nor more than 3.0%;
and
Mn: not less than 0.1% nor more than 2.0%;
a C content being 0.003% or less, and
a balance being composed of Fe and
inevitable impurity elements;
next, performing first cold-rolling of the steel
strip;
next, performing intermediate annealing of the
steel strip;
next, performing second cold-rolling of the steel
strip; and
next, performing finish annealing of the steel
strip, wherein
a finish temperature in the hot-rolling is 9 0 0 " ~
or less,
the first cold-rolling is started without
performing annealing after the hot-rolling; and
a rolling reduction in the second cold-rolling is
not less than 40% nor more than 85%.
[0013] (2) The manufacturing method of a nonoriented
electrical steel sheet according to (I),
wherein the steel material contains, in mass%, one or
two selected from a group consisting of Sn: not less
than 0.02% nor more than 0.40% and Cu: not less than
0.1% nor more than 1.0%.
[0014] (3) The manufacturing method of a nonoriented
electrical steel sheet according to (1) or
(2), wherein the steel material contains, in mass%,
P: 0.15% or less.
[0015] (4) The manufacturing method of a nonoriented
electrical steel sheet according to any one
of (1) to (3), wherein the steel material contains,
in mass%, Cr: not less than 0.2% nor more than 10.0%.
ADVANTAGEOUS EFFECTS OF INVENTION
[0016] According to the present invention,
conditions in a process particularly from hot-rolling
to cold-rolling are appropriately specified, so that
it is possible to improve magnetic properties in a
rolling direction.
DESCRIPTION OF EMBODIMENTS
[0017] Hereinafter, an embodiment of the present
invention will be described in detail. In the
present embodiment, a steel material (slab) having a
predetermined composition is hot-rolled so as to form
a steel strip, and cold-rolling of the steel strip is
then performed twice with intermediate annealing
therebetween. Thereafter, the steel strip is
subjected to finish annealing. Moreover, a finish
temperature in the hot-rolling, namely, a temperature
in the finish rolling is 9 0 0 " ~or less, and the first
cold-rolling is started without performing annealing
after the hot-rolling. In other words, the first
cold-rolling is started while maintaining a metallic
structure of the steel strip at the end of the hotrolling.
Further, a rolling reduction in the second
cold-rolling is not less than 40% nor more than 85%.
[0018] Next, a composition of a steel material used
in the present embodiment will be described.
Hereinafter, " % " being a unit of content means
"mass%". The present embodiment uses, for example, a
steel containing Si: not less than 0.1% nor more than
4.0%, Al: not less than 0.1% nor more than 3.0%, and
Mn: not less than 0.1% nor more than 2.0%, a C
content of the steel being 0.003% or less, and a
balance of the steel being composed of Fe and
inevitable impurity elements. The steel may also
contain one or two of Sn: not less than 0.02% nor
more than 0.40% and Cu: not less than 0.1% nor more
than 1.0%, the steel may also contain P: 0.15% or
less, and the steel may also contain Cr: not less
than 0.2% nor more than 10.0%. The steel material
may be produced by making a steel melted in a
converter, an electric furnace or the like to be
subjected to continuous casting, or by making an
ingot using the steel and making the ingot to be
subjected to blooming.
[0019] Si has an effect of reducing an iron loss by
increasing an electrical resistance of a non-oriented
electrical steel sheet to reduce an eddy current
loss. Further, Si also has an effect of improving
punchability when the steel sheet is processed into a
shape of iron core or the like by increasing a yield
ratio. When a Si content is less than 0.1%, these
effects are insufficient. On the other hand, when
the Si content exceeds 4.0%, a magnetic flux density
of the non-oriented electrical steel sheet is
lowered. Besides, a hardness is excessively high, so
that the punchability is lowered and the workability
during the cold-rolling and the like is lowered.
Further, this also leads to an increase in cost.
Therefore, the Si content is not less than 0.1% nor
more than 4.0%. Moreover, in order to obtain better
magnetic properties, the Si content is preferably
2.0% or more.
[0020] All similar to Si, has an effect of reducing
the iron loss by increasing the electrical resistance
of the non-oriented electrical steel sheet to reduce
the eddy currknt loss. Moreover, A1 also has an
effect of increasing a ratio of a magnetic flux
density B50 to a saturation magnetic flux density Bs
(B50/Bs) to improve a magnetic flux density. When an
A1 content is less than 0.1%, these effects are
insufficient. On the other hand, when the A1 content
exceeds 3.0%, the saturation magnetic flux density
itself is lowered, resulting in that the magnetic
flux density is lowered. Further, when compared to
Si, A1 is difficult to cause an increase in hardness,
but, when the A1 content exceeds 3.0%, the yield
ratio is decreased to lower the punchability.
Therefore, the A1 content is not less than 0.1% nor
more than 3.0%. Further, in order to secure a high
saturation magnetic flux density and the like, the A1
content is preferably 2.5% or less. Here, the
magnetic flux density B50 is a magnetic flux density
under a condition where a frequency is 50 Hz, and the
maximum magnetizing force is 5000 A/m.
[0021] Mn has an effect of reducing the iron loss by
increasing the electrical resistance of the nonoriented
electrical steel sheet to reduce the eddy
current loss. Moreover, Mn also has an effect of
developing {110}<001> orientation, which is desirable
for the improvement in magnetic properties in the
rolling direction, by improving a primary
recrystallization structure. Furthermore, Mn
suppresses a precipitation of fine sulfide (MnS or
the like, for example), which inhibits the growth of
crystal grains. When a Mn content is less than 0.1%,
these effects are insufficient. On the other hand,
when the Mn content exceeds 2.0%, it is difficult for
crystal grains to grow during the intermediate
annealing, resulting in that the iron loss is
increased. Therefore, the Mn content is not less
than 0.1% nor more than 2.0%. Further, in order to
further reduce the iron loss, the Mn content is
preferably less than 1.0%.
[0022] C has an effect of increasing the iron loss,
and it may be also a cause of magnetic aging.
Further, when C is contained in a steel strip during
cold-rolling at room temperature, the development of
the {110)<001> orientation, which is desirable for
the improvement in the magnetic properties in the
rolling direction, is sometimes suppressed. These
phenomena are significant when a C content exceeds
0.003%. Therefore, the C content is 0.003% or less.
[0023] Sn has an effect of developing the {110)<001>
orientation, which is desirable for the improvement
in the magnetic properties in the rolling direction,
by improving the primary recrystallization structure,
and it also has an effect of controlling a {111)<112>
orientation and the like, which are undesirable for
the improvement in the magnetic properties.
Moreover, Sn has an effect of suppressing oxidation
and nitriding on a surface of the steel strip during
the intermediate annealing, and it also has an effect
of adjusting growth of crystal grains. When a Sn
content is less than 0.02%, these effects are
insufficient. On the other hand, when the Sn content
exceeds 0.40%, these effects saturate and, on the
contrary, the growth of crystal grains during the
intermediate annealing is sometimes suppressed.
Therefore, the Sn content is preferably not less than
0.02% nor more than 0.40%.
[0024] Cu, similar to Sn, has an effect of
developing the {110)<001> orientation, which is
desirable for the improvement in the magnetic
properties in the rolling direction, by improving the
primary recrystallization structure. When a Cu
content is less than 0.1%, this effect is
insufficient. On the other hand, when the Cu content
exceeds 1.0%, a hot embrittlement is caused,
resulting in that the workability in the hot-rolling
is lowered. Therefore, the Cu content is preferably
not less than 0.1% nor more than 1.0%.
[0025] P has an effect of increasing the yield ratio
to improve the punchability. However, when a P
content exceeds 0.15%, the hardness is increased too
much, and the embrittlement is caused. As a result,
the workability in the manufacturing process of the
non-oriented electrical steel sheet is lowered, and
the workability in a customer, namely, in a user of
the non-oriented electrical steel sheet is lowered.
Therefore, the P content is preferably 0.15% or less.
[0026] Cr has an effect of reducing the iron loss
such as a high-frequency iron loss by increasing the
electrical resistance of the non-oriented electrical
steel sheet to reduce the eddy current loss. The
reduction in the high-frequency iron loss is suitable
for enabling high-speed rotation of a rotary machine.
By enabling the high-speed rotation of the rotary
machine, it is possible to deal with the demand for
the realization of miniaturization and highefficiency
of the rotary machine. Moreover, Cr also
has an effect of suppressing a stress sensitivity.
By suppressing the stress sensitivity, a variation in
properties caused by a stress during processing such
as punching, and a variation in properties caused by
a stress variation during the high-speed rotation are
reduced. When a Cr content is less than 0.2%, these
effects are insufficient. On the other hand, when
the Cr content exceeds 10.0%, the magnetic flux
density is lowered and the cost is increased.
Therefore, the Cr content is preferably not less than
0.2% nor more than 10.0%.
[0027] The components of the steel except the abovedescribed
components may be Fe and inevitable
impurities, for example. Incidentally, when the Si
content ( % ) , the A1 content ( % ) and the Mn content
( % ) are represented by [Si], [All and [Mn],
respectively, a value obtained through an expression
" [Si] + [All + [Mn] /2" is preferably 4.5% or less. This
is for securing the workability in the processing of
cold-rolling and the like.
100281 Next, explanation will be made on experiments
by which it is concluded that conditions for the hotrolling,
the cold-rolling and the like are defined as
described above.
[0029] The present inventors first produced steel
slabs each containing components presented in Table 1
and a balance composed of Fe and inevitable
impurities. Then, hot-rolling of each steel slab was
conducted so as to produce a steel strip (hot-rolled
sheet), and cold-rolling was performed twice. At
this time, the first cold-rolling was started without
performing hot-rolled sheet annealing after the hotrolling,
and intermediate annealing was conducted at
1000°C for 1 minute between the two times of coldrolling.
A thickness of each steel strip after the
cold-rolling (cold-rolled sheet) was set to 0.35 mm.
Finish temperatures in the hot-rolling, thicknesses
of the hot-rolled sheets, thicknesses of the steel
strips after the first cold-rolling, and rolling
reductions in the second cold-rolling are presented
in Table 2. After performing the second coldrolling,
finish annealing was performed at 9 5 0 " ~fo r
30 seconds. As is apparent from table 2, a rolling
reduction in the first cold-rolling was set to 31.4%
to 36.4%. Then, a sample was taken from each steel
strip after the finish annealing, and as magnetic
properties thereof, a magnetic flux density B50 and
an iron loss W15/50 were measured. Here, the iron
loss W15/50 is an iron loss under a condition where a
frequency is 50 Hz, and the maximum magnetic flux
density is 1.5T. Results of these are also presented
in Table 2.
[0030] [Table 11
TABLE 1
COMPONENT OF STEEL SLAB (MASS%)
C I Si I A1 I Mn I P
[0031] [Table 21
TABLE 2
[0032] It can be understood that in the condition
where the hot-rolled sheet annealing is not
performed, the magnetic properties in the rolling
direction of the non-oriented electrical steel sheet
can be significantly improved by appropriately
combining the finish temperature in the hot-rolling
and the rolling reduction in the second cold-rolling,
as seen from Table 2. In other words, it can be said
that when the finish temperature in the hot-rolling
is 900°C or less, and the rolling reduction in the
second cold-rolling is not less than 40% nor more
than 85%, it is possible to obtain extremely good
magnetic properties in the rolling direction.
[0033] In a condition No. 1, the rolling reduction
in the second cold-, in a condition No. 5, the
rolling reduction in the second cold-rolling was set
to 87.0%, being over 85%. For this reason, in the
conditions No. 1 and No. 5, the magnetic properties
in the rolling direction were inferior to those in
conditions No. 2 and No. 4.
[0034] Further, in a condition No. 3, the rolling
reduction in the second cold-rolling was set to
65.0%, but, the finish temperature in the hot-rolling
was set to 9 5 7 " ~be~i ng over 950°C. For this reason,
the magnetic properties in the rolling direction were
inferior to those in the conditions No. 2 and No. 4.
[0035] As described above, in the condition where
the hot-rolled sheet annealing is not performed, by
setting the finish temperature in the hot-rolling to
900°C or less, and by setting the rolling reduction
in the second cold-rolling to not less than 40% nor
more than 85%, it is possible to obtain extremely
good magnetic properties in the rolling direction.
The following can be considered as the reason
thereof. To start the first cold-rolling with the
finish temperature in the hot-rolling being 900°C or
less and without performing the hot-rolled sheet
annealing is the same as to start the first coldrolling
while maintaining a metallic structure of the
steel strip at the end of the finish rolling.
Therefore, a high proportion of non-recrystallized
rolled texture having the {110)<001> orientation is
maintained. When the intermediate annealing is
performed under the state of maintaining the high
proportion of rolled texture, and then the second
cold-rolling is conducted at the rolling reduction of
not less than 40% nor more than 85%, crystal grains
in the {110)<001> orientation grow during
recrystallization caused by the finish annealing
performed after the cold-rolling. As described
above, the crystal grains in the {110)<001>
orientation contribute to the improvement in the
magnetic properties in the rolling direction.
Incidentally, in order to more securely maintain high
proportion of non-recrystallized rolled texture, it
is preferable to set the finish temperature to 860'~
or less.
[0036] Further, the effect obtained by setting the
finish temperature in the hot-rolling to 900'~ or
less, starting the first cold-rolling without
performing the hot-rolled sheet annealing, and
setting the rolling reduction in the second coldrolling
to not less than 40% nor more than 85% is
significant when the Si content is 2.0% or more,
which is a favorable content. This is because, when
the Si content is 2.0% or more, a proportion of nonrecrystallized
rolled texture is increased, and when
the recrystallization is once started, an activation
energy of the growth of crystal grains is increased,
resulting in that the growth of crystal grains in the
{110}<001> orientation is significantly facilitated.
[0037] Besides, regarding the Young's modulus in
each crystal orientation of the non-oriented
electrical steel sheet, the Young's modulus in the
{110}<001> orientation is smaller than the Young's
modulus in the crystal orientation such as the
{111}<112> orientation, which is undesirable for the
improvement in the magnetic properties. The texture
of the non-oriented electrical steel sheet
manufactured by the present embodiment has a
significantly developed {110}<001> orientation.
Therefore, the Young's modulus of the non-oriented
electrical steel sheet manufactured by the present
embodiment is relatively low. When the Young's
modulus is low, even if a compressive strain is
applied in a shrink fitting or the like when
producing an iron core from the non-oriented
electrical steel sheet, a compressive stress
generated due to the compressive strain is low.
Therefore, according to the present embodiment, it is
also possible to reduce the deterioration of magnetic
properties due to the compressive stress. In other
words, according to the present embodiment, it is
also possible to achieve an effect such that, in
addition to the realization of the improvement in the
magnetic properties in the rolling direction, the
reduction in the deterioration of magnetic properties
when the compressive strain is applied is also
realized by lowering the Young's modulus.
[0038] Incidentally, when the rolling reduction in
the second cold-rolling is less than 40%, a
proportion of random orientations increases.
Further, when the rolling reduction in the second
cold-rolling exceeds 85%, a proportion of not the
{110)<001> orientation but the {111)<112> orientation
increases. For this reason, in these cases, the
magnetic properties in the rolling direction do not
improve sufficiently.
[0039] Further, the non-oriented electrical steel
sheet manufactured through the method as above is a
suitable one as a material of iron cores of various
electric equipments. In particular, the non-oriented
electrical steel sheet is a desirable one as a
material of a divided iron core among iron cores of
rotary machines, and further, it is a desirable one
also as a material of iron cores of middle and small
sized transformers. For this reason, it is possible
to realize the high-efficiency and the
miniaturization in the fields of rotary machines,
medium and small sized transformers, electrical
components and the like which use the non-oriented
electrical steel sheets as materials of their iron
cores.
EXAMPLE
[0040] Next, experiments conducted by the present
inventors will be described. Conditions and so on in
these experiments are examples employed to verify
practicality and effects of the present invention,
and the present invention is not limited to these
examples.
[0041] (Example 1)
First, steel slabs each containing components
presented in Table 3 and a balance composed of Fe and
inevitable impurities were produced. Then, hotrolling
of each steel slab was conducted to produce a
steel strip (hot-rolled sheet), and cold-rolling was
performed twice. At this time, the first coldrolling
was started without performing hot-rolled
sheet annealing after the hot-rolling, and
intermediate annealing was conducted at 9 5 0 " ~fo r 2
minutes between the two times of the cold-rolling. A
thickness of each steel strip after the cold-rolling
was set to 0.35 mm. Finish temperatures in the hotrolling,
thicknesses of the hot-rolled sheets,
thicknesses of the steel strips after performing the
first cold-rolling, and rolling reductions in the
second cold-rolling are presented in Table 4. After
performing the second cold-rolling, finish annealing
was performed at 970°c for 40 seconds. As is
apparent from table 4, a rolling reduction in the
first cold-rolling was set to approximately 40%.
Further, a sample was taken from each steel strip
after the finish annealing, and as magnetic
properties thereof, a magnetic flux density B50 and
an iron loss W10/400 were measured. The iron loss
W10/400 is an iron loss under a condition where a
frequency is 400 Hz, and the maximum magnetic flux
density is 1.OT. Results of these are also presented
in Table 4.
[0042] [Table 31
TABEL 3
[0043] [Table 41
TABLE 4
iGNETIC FLUX
r.-..m 7m.r
IN KULLlNb
Abl'YUI DIRECTION DIRECTION REMARKS qqn ,?l, W10/400 (W/kg) I
CONDITION
No.
11
FINISH IRON ROSS
TEMPERATURE IN
HOT-ROLLING
("C)
846
13
14
1 l5 1 851 1 4.2
THICKNESS OF
HOT-ROLLED
SHEET
(mm)
1.8
839
8 4 4
EXAMPLE I 2.6
THICKNESS
AFTER FIRST
COLD-ROLLING (mm)
1.1
1.8
1.8
86.5
ROLLDING
RIEND USCETCIOONND
1.1
1.1
Mf
. UC.N JII I. 1 IN ROLLING I
1.70
68.2
68.2
COLD-ROT TklP
(8) I Y.," 1 1 ,
I
I I
15.7
68.2 1.76
1.77
1.77
LUI~IYXKHI I VI
13.5 I EXAMPLE
I I - - . . - - - - - - - - -
13.1
13.2
EXAMPLE
EXAMPLE
EXAMPLE
,-,n..-." R%m7,,-
[00441 In a condition No. 12, the rolling reduction
in the second cold-rolling was set to 30.0%, being
less than 40%. Further, in a condition No. 15, the
rolling reduction in the second cold-rolling was set
to 86.5%, being over 85%. For this reason, in the
conditions No. 12 and No. 15, the magnetic properties
in the rolling direction were inferior to those in
conditions No. 11, No. 13 and No. 14.
[0045] Further, in the condition No. 13, in which Sn
was contained, and the condition No. 14, in which Cu
was contained, the magnetic properties in the rolling
direction were better than those in the condition No.
11, in which Sn and Cu were not contained. As seen
from the results, it can be understood that when Sn
or Cu is contained, the magnetic properties in the
rolling direction are further improved. Moreover, as
is apparent from Table 4, it can be understood that,
according to the examples of the present invention,
it is possible to manufacture the non-oriented
electrical steel sheets excellent in magnetic
properties in the rolling direction.
[0046] (Example 2)
First, steel slabs each containing components
presented in Table 5 and a balance composed of Fe and
inevitable impurities were produced. Then, hotrolling
of each steel slab was conducted to produce a
steel strip (hot-rolled sheet) having a thickness of
2.3 nm, and cold-rolling was performed twice. At
this time, although the first cold-rolling was
started without performing hot-rolled sheet annealing
after the hot-rolling in conditions No. 21, No. 23
and No. 24, the first cold-rolling was conducted
after performing the hot-rolled sheet annealing at
950°C for 2 minutes in a condition No. 22. Further,
intermediate annealing was conducted at 980°C for 1
minute between the two times of cold-rolling. Finish
temperatures in the hot-rolling are presented in
Table 6. A thickness of each steel strip after the
first cold-rolling was set to 0.8 mm, and a rolling
reduction in the second cold-rolling was set to
62.5%, to thereby set a thickness of each steel strip
after the second cold-rolling to 0.30 mm. After
performing the second cold-rolling, finish annealing
was performed at 950'~ for 20 seconds. Further, a
sample was taken from each steel strip after the a
finish annealing, and as magnetic properties thereof,
the magnetic flux density B50 and the iron loss
W10/400 were measured. Results of these are
presented in Table 6.
[0047] [Table 51
TABLE 5
[0048] [Table 61
TABEL 6
No.
21
22
C
0.0017
0.0016
CONDITION
No.
2 1
IRON ROSS I
Si
3.05
3.01
FINISH
TEMPERATURE IN
HOT-ROLLING
1 0,-j
2 2
2 3
2 4
IN ROLLING REMARKS
DIRECTION
\ L J
836
I
12.8 I EXAMPLE
- a r 1 COMPARATIVE
A1
1.18
1.20
HOT-ROLLED
SHEET
ANNEALING
839
8 32
829
EXAMPLE
EXAMPLE
EXAMPLE
MAGNETIC FLUX
DENSITY
IN ROLLING
DIRECTION
B50 (T)
[0049] When comparing the condition No. 21 and the
condition No. 22, although they have similar
compositions of the non-oriented electrical steel
sheets, significantly excellent magnetic properties
in the rolling direction were obtained in the
condition No. 21. This is because, although the hotrolled
sheet annealing was not conducted in the
condition No. 21, the hot-rolled sheet annealing was
conducted in the condition No. 22.
[0050] Further, in the conditions No. 23 and No. 24,
Mn
0.35
0.33
NONE
9 5 0 ° ~ x 2 ~ 1 ~ ,
NONE
NONE
Cr
-
-
1.75
1.72
1.73
1.67
in which Cr was contained, the iron loss in the
rolling direction was significantly low, compared to
that in the condition No. 21, in which Cr was not
contained. As seen from the results, it can be
understood that when Cr is contained, the iron loss
in the rolling direction is further suppressed.
Moreover, as is apparent from Table 6, it can be
understood that, according to the examples of the
present invention, it is possible to manufacture the
non-oriented electrical steel sheets excellent in
magnetic properties in the rolling direction.
[ 0 0 5 1 ] It should be noted that the above embodiments
merely illustrate concrete examples of implementing
the present invention, and the technical scope of the
present invention is not to be construed in a
restrictive manner by these embodiments. That is,
the present invention may be implemented in various
forms without departing from the technical spirit or
main features thereof.
INDUSTRIAL APPLICABILITY
[ 0 0 5 2 ] The present invention may be utilized in an
industry of manufacturing electrical steel sheets and
an industry of utilizing electrical steel sheets, for
example. In short, the present invention may also be
utilized in an industry related to electric
equipments using electrical steel sheets. Further,
the present invention may contribute to technical
innovations of these industries.

CLAIMS
[Claim 1] A manufacturing method of a non-oriented
electrical steel sheet, comprising:
performing hot-rolling of a steel material so as
to form a steel strip, the steel material containing,
in mass%:
Si: not less than 0.1% nor more than 4.0%;
Al: not less than 0.1% nor more than 3.0%;
and
Mn: not less than 0.1% nor more than 2.0%;
a C content being 0.003% or less, and
a balance being composed of Fe and
inevitable impurity elements;
next, performing first cold-rolling of the steel
strip;
next, performing intermediate annealing of the
steel strip;
next, performing second cold-rolling of the steel
strip; and
next, performing finish annealing of the steel
strip, wherein
a finish temperature in the hot-rolling is 9 0 0 " ~
or less,
the first cold-rolling is started without
performing annealing after the hot-rolling; and
a rolling reduction in the second cold-rolling is
not less than 40% nor more than 85%.
[Claim 2] The manufacturing method of a non-oriented
electrical steel sheet according to claim 1, wherein
-
the steel material contains, in mass%, one or two
selected from a group consisting of Sn: not less than
0.02% nor more than 0.40% and Cu: not less than 0.1%
nor more than 1.0%.
[Claim 3] The manufacturing method of a non-oriented
electrical steel sheet according to claim 1, fierein
the steel material contains, in mass%, P: 0.15% or
less.
[Claim 4] The manufacturing method of a non-oriented
electrical steel sheet according to claim 2, wherein
the steel material contains, in mass%, P: 0.15% or
less.
[Claim 5] The manufacturing method of a non-oriented
electrical steel sheet according to claim 1, wherein
the steel material contains, in mass%, Cr: not less
than 0.2% nor more than 10.0%.
[Claim 6] The manufacturing method of a non-oriented
electrical steel sheet according to claim 2, wherein
the steel material contains, in mass%, Cr: not less
than 0.2% nor more than 10.0%.
[Claim 7] The manufacturing method of a non-oriented
electrical steel sheet according to claim 3, wherein
the steel material contains, in mass%, Cr: not less
than 0.2% nor more than 10.0%.
[Claim 8] The manufacturing method of a non-oriented
electrical steel sheet according to claim 4, wherein
the steel material contains, in mass%, Cr: not less
than 0.2% nor more than 10.0%.