SPECIFICATION
NON-ORIENTED ELECTRICAL STEEL SHEET AND METHOD OF
MANUFACTURING NON-ORIENTED ELECTRICAL STEEL SHEET
Technical Field
[0001]
The present invention relates to a non-oriented electrical steel sheet used as an
iron core of a motor for use mainly in, for example, an electric device and a hybrid
vehicle, and a method of manufacturing the non-oriented electrical steel sheet. The
present application claims priority based on Japanese Patent Application No.
2012-075258 filed in Japan on March 29,2012, the disclosures of which are incorporated
herein by reference in their entirety.
Background Art
[0002]
Due to environmental issues typified by global warming, and resource issues
such as the depletion of oil resources and anxiety over nuclear power resources, energy
conservation has been increasingly important.
Under such circumstances, the automobile fields, for example, have been making
remarkable progress in hybrid vehicles and electric vehicles that contribute to energy
conservation.
Further, in the household appliance fields, there is an increasing demand for
highly efficient air conditioners and refrigerators that consume less electric power.
These products commonly use motors, and hence, these motors are increasingly
required to have improved efficiency.
The motors in these products have been miniaturized in response to the need for
miniaturization and weight reduction, and further are designed to rotate at high speeds to
meet the need for outputting sufficient power.
In order to reduce increasing losses occurring from high rotational speed and the
resulting heat occurring in the devices, cores of the motors are required to be formed by a
non-oriented electrical steel sheet having reduced high-frequency iron loss.
Further, these motors need to generate high torque, and there is a demand for the
non-oriented electrical steel sheet to have increased saturation magnetic flux density: Bs,
especially at the time of motor acceleration.
[0003]
Since the eddy current loss accounts for a large portion of the iron loss in the
high-frequency iron loss, the iron loss can be reduced by increasing the resistivity of the
non-oriented electrical steel sheet, as described, for example, in Patent Document 1.
However, alloying, which is necessary to increase the resistivity, brings about a
problem of a reduction in the saturation magnetic flux density Bs.
Further, alloying makes the steel sheet significantly brittle, which has a large
adverse effect on the productivity.
In particular, if the amount of Si exceeds 3%, the reduction in Bs and brittleness
of the steel sheet become notable, which makes it extremely difficult to achieve all the
desired magnetic properties and productivity.
In Patent Document 1, the amount of Si + Al is controlled to be less than or equal
to 4.5%. However, this control is not sufficient enough to pre\'ent the steel sheet from
becoming brittle. Further, Patent Document 1 does not take into consideration the effect
of Mn, which is the main point of the present invention.
Yet further. Patent Document 1 does not evaluate Bs. and hence, favorable
magnetic property cannot be necessarily obtained.
[0004]
Patent Document 2 describes making the relationship between resistivity and Bs
constant. However, Patent Document 2 is not intended to obtain high torque, and cannot
prevent the steel sheet from becoming brittle.
Further, Patent Document 2 is not directed at improving iron loss at high
frequencies, and does not take into consideration brittleness of a steel sheet having the
amount of Si exceeding 3.0% or improvement in the iron loss of the steel sheet. Thus,
favorable magnetic properties cannot be necessarily obtained.
Related Art Documents
Patent Document
[0005]
Patent Document 1: Japanese Unexamined Patent Application. First Publication
No. HI0-324957
Patent Document 2: Japanese Unexamined Patent Application. First Publication
No. 2010-185119
Disclosure of the Invention
Problems to be Solved by the Invention
[0006]
The present invention is directed to solving the problems that the conventional
arts described above have, and provides a non-oriented electrical steel sheet that has
reduced iron loss, increased satui-ation magnetic flux density Bs, and exhibits excellent
productivity, and a method of manufacturing the non-oriented electrical steel sheet.
More specifically, the present invention provides a non-oriented electrical steel sheet "with
reduced high-frequency iron loss and increased Bs without causing deterioration in
productivity, and a method of manufacturing the non-oriented electrical steel sheet.
Means for Solving the Problem
[0007]
The main points of the present invention will be described below.
[0008]
(1) A first aspect of the present invention relates to a non-oriented electrical steel
sheet consisting of, in mass%: C: not less than 0.0001% and not more than 0.0040%, Si:
more than 3.0% and not more than 3.7%), sol.Al: not less than 0.3% and not more than
1.0%, Mn: not less than 0.5% and not more than 1.5%, Sn: not less than 0.005% and not
more than 0.1%, Ti: not less than 0.0001% and not more than 0.0030%. S: not less than
0.0001% and not more than 0.0020%, N: not less than 0.0001% and not more than
0.003%, Ni: not less than 0.001% and not more than 0.2%, and P: not less than 0.005%
and not more than 0.05%, with a balance consisting of Fe and impurities, in which a
resistivity p at room temperature > 60 \xQ.cm, and saturation magnetic flux density Bs at
room temperature > 1.945T are estabhshed, and the components contained satisfy 3.5 < Si
+ (2/3) X sol.Al + (1/5) X Mn < 4.25.
(2) A second aspect of the present invention relates to a method of manufacturing
the non-oriented electrical steel sheet according to (1) described above, including:
hot-rolling a slab containing the chemical components specified in (1) described above;
after the hot-rolling, applying hot-rolled-sheet annealing or self-annealing, or without
applying the hot-rolled-sheet annealing, and applying pickling in either case: applying
cold-rolling once, or cold-rolling twice with intermediate annealing applied between
applications of cold-rolling; and after the cold-rolling, applying tinal-annealing, and
applying coating, in which, during the cold-rolling, the temperature of a steel sheet at the
start of the cold-rolling is set to not less than 50°C and not more than 200°C, and the rate
at which the steel sheet passes through a first pass during rolling is set to not less than 60
m/min and not more than 200 m/min.
Eflects of the Invention
[0009]
According to the present invention, it is possible to provide a non-oriented
electrical steel sheet exhibiting reduced high-frequency iron loss and improved saturation
magnetic flux density Bs while maintaining high productivit>. and a method of
manufacturing the non-oriented electrical s-teel sheet.
The present invention contributes to achieving highly efficient.
high-performance motors for use in hybrid vehicles and electric vehicles in the field of
automobiles, and in air conditioners and refrigerators in the field of household appliances,
and fiirther can maintain high productivity, which makes it possible to achieve reduced
manufacturing costs.
Brief Description of the Drawings
[0010]
FIG. 1 is a diagram illustrating an example of ranges of components according to
the present invention.
Embodiments of the Invention
[0011]
The present inventors made a keen study on elements in a steel sheet and
manufacturing conditions to solve the problems described above with regard to providing
a non-oriented electrical steel sheet in line with the current tread of motors, in other words,
achieving a non-oriented electrical steel sheet with magnetic properties having both
sufficiently low high-frequency iron losses and high saturation magnetic flux density Bs
in the case where the amount of Si is set to over 3.0%, while, from the viewpoint of
manufacturing, the steel sheet maintains its toughness during manufacturing.
As a result, the present inventors revealed that it is possible to prevent
deterioration in productivity while maintaining low high-frequency iron loss and high Bs
by making the steel contain Si, sol.Al, and Mn in a well-balanced manner.
In particular, for Si, sol.Al, and Mn, the present inxentors re\ ealed that the
degree of brittleness can be evaluated by using Si + (2/3) x sol.Al •+ (1 /5) x Mn, and
further found that it is possible to alleviate the brittleness and reduce the risk of breakage
during the time when the steel sheet is running, by setting this value to not more than
4.25.
Further, the present inventors found that the risk of breakage during the time
when the steel sheet is running can be effectively reduced by appropriately controlling
temperatures of the steel sheet at the time of running the cold-drawn steel sheet, in
addition to setting the chemical components in the range described above.
[0012]
Below, a non-oriented electrical steel sheet (hereinafter, also referred simply to
as a steel sheet) according to an exemplary embodiment of the present invention that has
been made on the basis of the findings described above will be described in detail.
[0013]
First, a reason for limiting the chemical composition of the steel sheet will be
described.
It should be noted that"%" and "ppm," each of which indicates the amount of
content, mean "mass%" and "mass ppm", respectively, unless otherwise specified.
[0014]
(C: not less than 0.0001% and not more than 0.0040%)
C causes magnetic aging, which leads to a deterioration in the magnetic
properties, and it is desirable to minimize C as much as possible. Thus, C is set to not
more than 0.0040%.
The amount of C contained is preferably set to not more than 0.0030%, and more
preferably set to not more than 0.0025%.
Further, from the viewpoint of manufacturing load, the lower limit of the amount
of C contained is set to 0.0001%, and preferably to 0.0003%.
[0015]
(Si: more than 3.0%) and not more than 3.7%)
Si is an element that increases the resistivity of the electrical steel sheet and
effectively reduces the iron loss. Fuilher, Si has an economical advantage of increasing
the resistivity at low cost. Thus, it is necessary for Si to exceed 3.0%.
In the case where Si is less than or equal to 3.0%. it is necessary to increase the
6
amount of other expensive elements to obtain the resistivity p > 60 pHcm, and hence, this
amount of Si is not desirable.
On the other hand, if the amount of Si added increases, the iron loss can be more
effectively reduced. However, an excessive amount of Si added makes the steel sheet
brittle, which significantly increases the risk of breakage during manufacturing. Thus,
the upper limit of the amount of Si contained is set to 3.7%, and preferably to 3.5%.
[0016]
(sol.Al: not less than 0.3% and not more than 1.0%))
sol.Al is an element that increases the resistivity of the electrical steel sheet.
However, sol.Al greatly contributes to the reduction in Bs. and has a large effect
on the brittleness of the steel sheet. Thus, the upper limit of the amount of sol.Al
contained is set to 1.0%, preferably to 0.9%), and more preferably to 0.8%.
Further, in the case where the amount of sol.Al contained is excessively low, the
resistivity becomes low. Further, nitrides such as AIN finely precipitates, which leads to
a deterioration in grain growth. This may worsen the iron loss. Thus, the lower limit
of the amount of sol.Al contained is set to 0.3%, preferabl}' to 0.4%. and more preferably
to 0.5%.
[0017]
(Mn: not less than 0.5%) and not more than 1.5%)
Mn is an element that increases resistivity of the electrical steel sheet without
causing any serious deterioration in the brittleness of the steel sheet, and can effectively
reduce the iron loss. Thus, Mn of 0.5% or more is necessaiy.
If the amount of Mn added is increased, the iron loss can be more effectively
reduced. However. Mn causes the foniiation of austenite. and hence, if the amount of
Mn is excessive, the phase is changed from a single phase fonned only by fenite during a
high-temperature process in the manufacturing processing, which may significantly
deteriorate the magnetic properties of the resulting sheet produced.
For this reason, the upper limit of the amount of Mn contained is set to 1.5%. and
7
preferably to 1.3%.
[0018]
To reduce the high-frequency iron loss, it is necessary to appropriately adjust the
amount of Si, sol.Al, and Mn added.
As a result of study, it was found that it is necessar>' to set the resistivity at room
temperature to not less than 60 laHcm to obtain the favorable high-frequency iron loss.
It should be noted that the resistivity at room temperature was obtained through a
generally known four-terminal method.
[0019]
To obtain ftirther favorable motor characteristics, it is necessary to set the
saturation magnetic flux density Bs at room temperature to Bs > 1.945T.
The saturation magnetic flux density Bs at room temperature itself is an
important magnetic property that contributes, for example, to motor torque.
Further, the saturation magnetic flux density Bs at room temperature directly
affects the magnetization process, and has an effect on the iron loss. Thus, to obtain
favorable iron loss, it is important to design components \\hiie taking the saturation
magnetic flux density Bs at room temperature into consideration.
To this end, it is desirable to reduce the amount of sol.Al contained that causes a
large reduction in Bs, whereas it is desirable to increase the amount of Mn added in view
of the necessity to ina-ease the resistivity described above and the influence on brittleness
described below.
Bs was measured, for example, thi'ough a vibrating sample magnetometer
(VSM).
[0020]
In addition to these, by satisfying Si + (2/3) x sol.Al + (1/5) x Mn < 4.25, it is
possible to manufacture a non-oriented electrical steel sheet that exhibits excellent
magnetic properties while significantly reducing risks such as breakage during
manufacturing, thereby preventing the deterioration in productivity
8
Here, Si, sol.Al, and Mn each represent values when contents in the steel sheet
are expressed in terms of mass%).
As the value of Si + (2/3) x sol.Al + (1/5) x Mn decreases, the toughness of the
steel sheet increasingly improves, and the risk of breakage during the time when the steel
sheet is running further reduces.
Thus, from the viewpoint of running the steel sheet, the upper limit of Si + (2/3)
X sol.Al + (1/5) X Mn is set preferably to 4.1, and more preferably to 4.0. However, due
to the necessity of setting the resistivity at room temperature to not less than 60 \iD.cm, it
is necessary to appropriately adjust the balance between the amounts of Si, sol.Al, and
Mn added. In other words, it is difficult to obtain the desired resisti\ity if the value of Si
+ (2/3) X sol.Al + (1/5) X Mn is less than 3.5, and hence, the lower limit value of Si +
(2/3) X sol.Al + (1/5) X Mn is set to 3.5, preferably to 3.6, and more preferably to 3.7.
[0021]
To increase the resistivity while considering the influence on Bs and brittleness
as described above, it is desirable to use Mn rather than sol.Al. and it is preferable to
satisfy sol.Al < Mn.
Further, it is fiirther preferable to satisfy Mn > 0.7% to siifliciently increase the
resistivity.
[0022]
(Sn: not less than 0.005% and not more than 0.1%)
Sn has an effect of improving texture after final-annealing to improve the B50
(magnetic flux density at the time of magnetization at 5000 A/m), and hence, tlie amount
of Sn contained is set to not less than 0.005%, and preferabh- 0.01 %.
This effect is enhanced with the increase in the amount of Sn added. However,
if the amount of Sn contained is 0.1% or more, the effect saturates, and the steel sheet
becomes brittle, which increases the risk of breakage at the time when the steel sheet is
ninning. Thus, the upper limit is set to 0.1%, preferably to 0.9%. and more preferably to
0.8%.
[0023]
(Ti: not less than 0.0001% and not more than 0.0030%)
Ti precipitates in a form of, for example, TiN or TiC, which leads to a
deterioration in magnetic properties and grain growth at the time of tmal-annealing.
Thus, it is desirable to reduce Ti as much as possible, and the amount of Ti contained is
set to 0.0030% or less, and preferably to 0.0025% or less.
However, from the viewpoint of manufacturing loads, the lower limit of the
amount of Ti contained is set to 0.0001%, and preferably to 0.0003%.
[0024]
(S: not less than 0.0001% and not more than 0.0020%)
S precipitates in a fonn of, for example, MnS, MgS. TiS. or CuS, which leads to
a deterioration in magnetic properties and grain grovrth at the time of final-annealing.
Thus, it is desirable to reduce S as much as possible.
These sulfides are more likely to precipitate in a fine fomi. and have a large
effect on the deterioration in hysteresis loss of the iron loss.
Thus, the amount of S contained is set to not more than 0.0020% or less, and
preferably to not more than 0.0015%).
However, from the viewpoint of manufacturing load, the lower limit of the
amount of S contained is set to 0.0001%, and preferably to 0.0003%.
[0025]
(N: not less than 0.0001% and not more than 0.003%)
N precipitates in a form of, for example, TiN or AIN. w hich leads to a
deterioration in magnetic properties and grain growth at the time of final-annealing.
Thus, it is desirable to reduce N as much as possible.
For this reason, the amount of N contained is set to not more than 0.0030%, and
preferably to 0.0025%.
However, from the viewpoint of manufacturing load, the lower limit of the
amount of N contained is set to 0.0001 %. and preferably to 0.0003%.
10
[0026]
As described above, C, Ti, S, and N form precipitates, which leads to an increase
in the hysteresis loss.
To reduce the high-frequency iron loss, it is effective to increase the resistivity
that lowers the eddy current loss. However, this may cause deterioration in productivity
resulting from brittleness as well as deterioration in Bs, which is one of the important
magnetic properties.
It is desirable to achieve a sufficiently reduced high-frequenc}' iron loss target
while reducing the alloy components as much as possible. Thus, it is preferable to
reduce these C, Ti, S, and N as much as possible.
[0027]
(Ni: not less than 0.001% and not more than 0.2%)
Ni has an effect of improving toughness of the steel sheet to reduce the risk of
breakage during manufacturing. Thus, Ni is set to not less than 0.001%.
Ni provides a higher effect with the increase in the amount ofNi added.
However, for economic reasons, the upper limit of Ni is set to 0.2%.
[0028]
(P: not less than 0.005% and not more than 0.05%)
P has an effect of improving textui-e after final-annealing to improve the B50,
and hence, P is set to not less than 0.005%.
This effect is enhanced with the increase in the amount of P added. However, if
the amoimt of P contained exceeds 0.05%, the steel sheet becomes brittle, which increases
the risk of breakage at the time when the steel sheet is ranning. Thus, the upper limit is
set to 0.05%, and preferably to 0.03%.
[0029]
The chemical composition of the steel sheet described above contains Fe and
impurities as the remainder other than the elements described above. The remainder
may only consist of Fe and impurities. The impurities include, for example, O and B.
11
which are inevitable impurities entering during manufacturing processes or other
processes, and Cu, Cr, Ca, REM, and Sb, which are very small amounts of elements
added for obtaining favorable magnetic properties. These impurities may be contained
within a range that does not impair mechanical properties and magnetic properties of the
present invention.
[0030]
An example of the ranges of components according to the present invention is
illustrated in FIG. 1.
The portions surrounded by the outlines illustrate appropriate ranges of sol.Al
and Mn with the amount of Si added being varied to 3.2%. 3.5%. and 3.7%. Note that
portions of the lines overlapping with each other are illustrated so as to be appropriately
shifted from each other.
For 3.2% Si illustrated with the sohd line, the limitations of 0.3% < sol.Al <
1.0% and 0.5% < Mn < 1.5%) are applied; the limitation of p > 60 |.iQcm is applied to the
portion where the amounts of sol.Al and Mn are low; and the limitation of Bs > 1.945T is
applied to the portion where the amounts of sol.Al and Mn are large. Thus, the inside of
the hexagon surrounded by these lines represents the ranges of the components according
to the present invention.
The limitation of components using Si + (2/3) x sol.Al + (1/5) x Mn < 4.25,
which is used for evaluating the degree of brittleness, is effective in the case where the
amount of Si is high. In the case of 3.7% Si, the inside of the trapezoid surrounded with
the dot-and-dash line illustrating the limitations of 0.3%) < sol.Al and 0.5% < Mn < 1.5%
and the limitation of Si + (2/3) x sol.Al + (1/5) x Mn < 4.25 represents the desirable
ranges of the components.
In view of the relationship between sol.Al and Mn. there is a slight difference in
coefficient between the limitation by Bs > 1.945T and the limitation b\- Si + (2/3) x sol.Al
+ (1/5) X Mn < 4.25. Thus, in the case of 3.5% Si, the inside of the hexagon as
illustrated with the dotted line having the crossing point ai Mn ^ 1.0% represents the
12
range of the components according to the present invention for 3.5% Si.
Next, the conditions for manufacturing the steel sheet according to this
embodiment will be described.
[0031]
As a base steel formed by the components described above, it may be possible to
use a steel slab produced through melting in a converter and then a continuous casting or
ingot-casting primaiy rolling process.
The steel slab is heated through a known method, and then is subjected to
hot-rolling into a hot-rolled sheet having a required thickness.
After this, the hot-rolled sheet is subjected to annealing or self-annealing as
necessary.
This hot-rolled sheet is subjected to pickling, and then is cold-rolled, or
cold-rolled twice, including intermediate annealing, to forai the sheet so as to have a
predetemiined thickness. Tlien, the sheet is subjected to fmal-annealing, and is
insulation-coated.
[0032]
In addition to the manufacturing condition described abo\e, b\' increasing
temperature of the steel sheet at the start of rolUng in the cold-rolling and reducing the
rate at which the sheet passes through the cold-rolling in the first pass, it is possible to
further reduce the risk of breakage during the cold-rolling and the following
final-annealing.
The temperature needs to be set to not less than 50°C. and the resulting effect
can be enhanced with the increase in the temperature. Ho\\e\er. from the viewpoint of
the load on facilities, the upper limit of the temperature is set to 200^C.
Further, by setting the rate at which the sheet runs to not more than 200 m/min,
the effect of reducing the risk of breakage can be achieved. Howe^ er. if the rate at
which the sheet runs is excessively low, the effect of increasing the temperature of the
steel sheet using the heat generated from working processes is signiiicantly reduced, and
13
the effect of reducing the risk of breakage resulting from the increase in the temperature
of the steel sheet in the second pass or after is reduced.
In addition, the cost required for rolling significantly increases, and hence, the
lower limit of the rate is set to 60 m/min.
[0033]
It should be noted that the eddy current loss of the iron loss can be more
effectively reduced with the reduction in the thickness of the product sheet.
In general, the sheet is manufactured with a thickness of not more than 0.50 mm.
However, it is desirable to set the thickness to not more than 0.30 mm to reduce the iron
loss, and further, more favorable iron loss can be obtained b}- setting the thickness to not
more than 0.25 mm.
On the other hand, the excessively thin thickness has an ad\erse effect on the
productivity of the steel sheet or increases the cost required for manufacturing motors.
Thus, the thickness is set preferably to not less than 0.10 mm. and more preferably to not
less than 0.20 mm.
Below, examples of the present invention will be described.
Example 1
[0034]
Steel slabs containing various components shown in Table 1 adjusted
appropriately in a manner such that the steel slabs had a resisti\ ity p of approximately 60
^Qcm, with the balance including Fe and inevitable impurities, were prepared. The steel
slabs were hot-rolled so as to have a thickness of 2.0 mm. the sheets were subjected to
hot-rolled-sheet annealing at 1000°C x 1 minute, pickling, and then cold-rolled so as to
have a thickness of 0.30 mm.
It should be noted that, in the first pass of the cold-rolling, the temperature of
each of the sheets was set to 70°C, and the rate at which the sheets were run was set to
100nx''min.
14
The cold-rolled sheets were subjected to final-.^ealing at 1000°C x 15 seconds,
and were insulation-coated.
The magnetism measurement was evaluated using an iron loss (Wl0/800)
obtained at the time when sinusoidal magnetization was performed at a cycle of 800 Hz
with the maximum magnetic flux density of 1 .OT.
The existence or absence of breakage was evaluated by judging whether
breakage occurred during cold-rolling and final-armealing when three coils were
processed.
[0035]
In all the coils, the values of Si + (2/3)sol.Al + (l/5)Mn were lower than 4.25,
and no breakage was found in any of the coils.
However, No. 1 to No. 4 had a resistivity of 60 LiQcm or lower, and as a result,
the iron loss W10/800 exceeded 38 W/kg.
No. 5 to No. 12 had a resistivity of 60 jaQcm or higher. However, No. 6 to No.
8 had an iron loss Wl0/800 exceeding 38W/kg, and had Bs lower than 1.970T, exhibiting
poor magnetic properties.
One of the reasons that the iron loss was poor relative to the resistivity is
considered to be the low Bs, which is another important magnetic property.
In these steel sheets, any one of or both of sol.Al and Mn fell outside the range of
the present invention.
On the other hand. No. 5 and No. 9 to No. 12 had an iron loss Wl0/800 less than
or equal to 38W/kg, and had high Bs more than or equal to 1.970T. which resulted in
excellent magnetic properties having a good balance between iron loss and Bs.
Further, of these samples. No. 9 and No. 12 having sol.Al < Mn and Mn > 0.7%
resulted in not more than 37.7W/kg and Bs of 1.980T, and exhibited particularly
favorable iron loss.
[0036]
[Table 1]
15
No.
1
2
-^
4
5
6
7
X
III
1 i
12
C
(ppra)
18
20
23
23
2-4
25
17
26
27
24
20
23
Si
(mass%)
3.01
3.03
3.38
3.05
3.27
3.01
3.05
3.23
3.24
3.26
.v5l
3.48
sol.AI
(niass%)
0.61
0.98
0.35
0.36
0.58
1.02
1.13
0.93
0.33
(1.71
0.42
0.31
Mn
(mass%)
0.92
0.25
0.53
1.21
0.65
0.51
0.32
0.21
1,14
0.52
0.51
0.71
Sn
(mass%)
0.054
0.078
0.066
0.034
0.024
0.034
0.059
0.026
0.062
0 047
0.03X
0.069
Ti
(ppm)
13
15
12
11
16
15
16
11
16
12
16
12
S
(ppm)
17
12
17
17
11
7
13
17
12
15
13
16
N
(ppm)
17
14
16
12
13
13
12
16
16
15
14
11
Ni
(niaj;s%)
0.07
0.07
0.06
0.02
0.08
0.02
0.06
0.06
0.07
0.03
0,07
0.01
p
(mass%)
0.019
0.010
0.014
0.008
0.010
0.0 IS
0.014
0.013
0.011
o.oox
O.UIO
0.015
Resistivity
nCicm
59.5
59.1
59.0
59.5
60.7
60.9
61.3
60.8
61.1
61.0
61,1
61.0
Bs
(T)
1.979
1.971
1.986
1.985
1.975
1.964
1.960
1.966
1.980
1.971
1.077
1.980
W10/800
(W/kg)
38.35
38.73
38.21
38.18
37.96
38.29
38.26
38.20
37.69
37.97
37.75
37.63
Si+(2/3)sol.Al
+(I/5)Mn
3.60
3.73
3.72
3.53
3.79
3.79
3.87
3.89
3.69
3.84
3.89
3.83
Breakage
No
No
No
No
No
No
No
No
No
No
No
No
Note
Comparative Example
Comparative Example
Comparative Example
Comparative Example
Example of the present
invention
Comparative Example
Comparative Example
Comparative Example
Example of the present
invention
example of (lie presciU
invcnlion
[Tximiple of the present
invention
Example of the present
invention
16
Example 2
[0037]
Steel slabs containing various components shown in Table 2 adjusted
appropriately in a manner such that the steel slabs had a resistivity p at room
temperature of approximately 65 jiQcm, with the balance including Fe and
inevitable impurities, were prepared. The steel slabs were hot-rolled so as to have
a thickness of 2.0 mm, subjected to hot-rolled-sheet annealing at 1000°C x 1 minute,
pickling, and then cold-rolled so as to have a thickness of 0.30 mm. Note that, in
the first pass of the cold-rolling, the temperature of each of the sheets was set to
70°C, and the rate at which the sheets were run was set to 100 m/min.
The cold-rolled sheets were subjected to final-annealing at 1000°C x 15
seconds, and were insulation-coated.
The magnetism measurement was evaluated using an iron loss obtained at
the time when sinusoidal magnetization was performed at a cycle of 800 Hz with
the maximum magnetic flux density of 1 .OT.
The existence or absence of breakage was evaluated by judging whether
breakage occurred during cold-rolling and final-annealing when three coils were
processed.
[0038]
No. 15 and No. 19 having the value of Si + (2/3)sol.Al + (l/5)Mn
exceeding 4.25 broke in the first.pass in cold-rolling, and a large number of small
cracks were found on the end surface in the width direction of the cold-rolled coils.
Further, some coils broke in the following final-annealing.
Other samples were able to pass through without causing any breakage.
No. 14, No. 18. and No. 22 had an iron loss W10/800 exceeding 37.0 W/kg and Bs
falling under 1.945T, which is a criterion according to the present invention.
In the case of these steel sheets, any one of or both of sol.Al and Mn fell
outside the range of the present invention.
No. 13, No. 16, No. 17, No. 20, and No. 2 Tare examples of the present
invention, and had a favorable iron loss lower than 37.0 W/kg as well as Bs
exceeding 1.945T, which resulted in both excellent iron los.'^ and Bs.
17
#
In particular. No. 13, No. 16, and No. 20 having sol.Al < Mn and Mn >
0.7% resulted in less than 36.6 W/kg and Bs of not less than 1.960T, and exhibited
favorable iron loss.
[0039]
[Table 2]
18
u
o z
0 0
CO
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CQ
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z
z
C/1
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c ^ 3
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K
CJ
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1 *—'
b
1
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s I
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I
S
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1 a
I
e
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=5
3
,—^
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•? I
^
•S; 1
„ ^
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(U
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Ci c
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f*S
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>i-)
SO
m
So• *
•n
so

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d

0 . 92
0.73
0.43
Mil
(mass%)
1.48
1.34
1.25
1.13
1.47
0.90
1.09
I.IO
0.42
0.')5
1.05
1.27
1.28
Sn
(mass%)
0.010
0.045
0.010
0.044
0.013
0.009
0.022
0.027
0.0 IS
0030
0.014
0.018
0.018
Ti
(ppm)
16
13
11
8
12
15
8
11
16
12
15
15
8
S
(ppm)
8
11
6
8
8
9
6
7
5
X
,S
5
9
N
(ppm)
12
10
13
10
14
13
12
11
13
III
1 1
13
13
Ni
(mass"/o)
0.12
0.10
0.06
0.11
0.08
0.11
0.13
0.08
O.OC
004
0.06
0.05
0.11
P
(mass%)
0.012
0.010
0.013
0.011
0.009
0.011
0.011
0.009
o.oox
0.01 1
0010
0.010
O.OIO
Resistivity
(iflcm
69,0
69.0
69.2
68.9
69.0
68.8
69.0
69.1
68.8
60.0
69.0
69.0
69.1
Bs
(T)
1.964
1.948
1.936
1.941
1.952
1.928
1.940
1.947
1.920
1.932
1.941
1.945
1.952
W10/800
(W/kg)
35.86
35.74
36.17
36.03
35.61
36.58
36.02
-
-
i(-<.i}
36.01
35.85
35.55
Si+(2/3)sol.Al
+(l/5)Mn
4.16
4.22
4.20
4.24
4.20
4.23
4.26
4.31
4.34
4.26
4.27
4.23
4,27
Breakage
No
No
No
No
No
No
Exist
Exist
Exist
|-;xisl
Hxisl
No
Exist
Note
Example of the present
invention
Example of the present
invention
Comparative Example
Comparative Example
Example of the present
invention
Comparative Example
Comparative Example
Comparative Example
Compar.itive Example
Comparative Example
Comparativi; Example
Example of (he present
invention
Comparative Example
22
Example 4
[0043]
Steel slabs containing C: 0.0012%, Sn: 0.023%, Ti: 0.0011%, S: 0.0007%,
N: 0.0014%, Ni: 0.046%, P: 0.011%, Si: 3.26%, sol.Al: 0.98%, and Mn: 0.72% (Si
+ (2/3)sol.Al + (l/5)Mn = 4.06), with the balance including Fe and inevitable
impurities, were hot-rolled so as to have a thickness of 2.0 mm. Then, the
hot-rolled sheets were subjected to hot-rolled annealing at 1000°C x 1 minute,
pickling, and then cold-rolled so as to have a thickness of 0.30 mm.
It should be noted that the cold-rolling was performed while temperatures
of each of the sheets and the rate at which the sheets were run were varied in the
first pass of the cold-rolling in accordance with the values as shown in Table 4.
The cold-rolled sheets were subjected to final-annealing at 1000°C x 15
seconds, and were insulation-coated.
The existence or absence of breakage was evaluated by judging whether
breakage occurred during cold-rolling and final-annealing when three coils were
processed.
[0044]
No. 36 passed through the first pass at a slow rate. Hence, temperatures of
the coils were reduced in the second pass, and breakage occurred during the
cold-rolling.
No. 41 passed through at a rate faster than the range of the present
invention, and breakage occurred during the cold-rolling. Further, the shape of the
cold-rolled sheet was poor, and breakage occurred in the following final-annealing.
No. 42 and No. 43 passed through the first pass at temperatures lower than
the range of the present invention, and breakage occurred in the first pass during
rolling. Further, a large number of small cracks were found on the end surface of
the coil in the width direction, and breakage occurred in the following
final-annealing.
No. 37 to No. 40 and No. 44 to No. 46 fell within the range of the present
invention, and passed through without causing any breakage.
[0045]
23
[Table 4]
No.
36
37
38
39
40
41
42
43
44
45
46
Sheet-passing rate in
first pass
(m/min)
50
60
100
150
180
230
100
100
100
100
100
Temperature of sheet
passing through first
pass
(°C)
73
68
81
83
77
85
31
47
65
91
138
Breakage
Exist
No
No
No
No
Exist
Exist
Exist
No
No
No
Note
Comparative Example
Example of the present invention
Example of the present invention
Example of the present invention
Example of the present invention
Comparative Example
Comparative Example
Comparative Example
Example of the present invention
Example of the present invention
Example of the present invention
Example 5
[0046]
Steel slabs containing various components shown in Table 5 adjusted
appropriately in a manner such that the steel slabs had a resistivity p at room
temperature of approximately 69 i^Qcm, with the balance including Fe and
inevitable impurities, were prepared. The steel slabs were hot-rolled so as to have
a thickness of 2.0 mm, the hot-rolled sheets were subjected to pickling without
application of hot-rolled-sheet annealing, and then cold-rolled so as to have a
thickness of 0.30 mm.
It should be noted that, in the first pass of the cold-rolling, the temperature
of each of the sheets was set to 70°C, and the rate at which the sheets were run was
set to 100 m/min.
The cold-rolled sheets were subjected to final-annealing with 1050°C x 15
seconds, and were insulation-coated.
The magnetism measurement was evaluated using an iron loss obtained at
the time when sinusoidal magnetization was performed at a cycle of 800 Hz with
the maximum magnetic flux density of LOT.
The existence or absence of breakage was evaluated by judging whether
breakage occured during cold-rolling and final-annealing when three coils were
processed.
No. 50 having the value of Si + (2/3)sol.Al + (l/5)Mn exceeding 4.25 had a
large number of breakages.
The breakage occurred in the first pass of the cold-rolling. Further, a large
number of small cracks were found on the end surface in the width direction of the
cold-rolled coil, and the shape of the cold-rolled sheet was poor.
It can be said that, for the samples without the hot-rolled-sheet annealing,
the risk of breakage can be evaluated by setting the value of Si + (2/3)sol.Al +
(l/5)Mn to not more than 4.25.
In the case where the hot-rolled-sheet annealing was not applied, the iron
loss Wl 0/800 was higher than that of No. 23 to No. 35 that had the hot-rolled-sheet
annealing applied thereto, although temperatures during final-:innealing were
increased to 1050°C.
Of the samples. No. 49 had an iron loss WlO/800 higher than 37.0 W/kg
and Bs lower than 1.945T, which is a criterion of the present invention.
In this coil, sol.Al fell outside the range of the present invention.
No. 47 and No. 48 are examples of the present invention and had a
favorable iron loss having W10/800 less than 37.0 W/kg and ha\ ing Bs more than
or equal to 1.945T.
[0047]
[Table 5]
25
No.
47
48
49
50
C
(ppm)
14
II
13
II
Si
(mass%)
3.47
3,63
3.15
3.44
sol.AI
(niass%)
0.75
0.45
1.14
1.02
Mil
(niass%)
1.26
1.41
1.31
0.91
Sn
(mass%)
0.013
0.042
0.043
0.041
ri
(ppm)
14
10
11
15
S
(ppm)
12
8
5
10
N
(ppm)
13
13
10
10
Ni
(mass%)
0.04
0.12
0.13
0.11
P
(mass%)
0.012
0.011
0.011
0.007
Resistivity
jificm
68.9
68.9
69.2
68.9
Bs
(T)
1.945
1.952
1.936
1.938
W10/800
(W/kg)
36.90
36.64
37.20
37.10
Si+(2/3)sol.AI
+(l/5)Mn
4.22
4.21
4.17
4.30
Breakage
No
No
No
Exist
Note
Example of the present
invention
Example of the present
invention
Comparative Example
Comparative Example
26
Industrial Applicability
[0048]
According to the present invention, it is possible to provide a non-oriented
electrical steel sheet having reduced iron loss and increased saturation magnetic
flux density Bs, and exhibiting excellent productivity, and a method of
manufacturing the non-oriented electrical steel sheet.
27

CLAIMS ^\»r.^»*
1. A non-oriented electrical steel sheet, consisting of, in mass%:
C: not less than 0.0001% and not more than 0.0040%.
Si: more than 3.0% and not more than 3.7%,
sol.Al: not less than 0.3% and not more than 1.0%,
Mn: not less than 0.5%) and not more than 1.5%,
Sn: not less than 0.005% and not more than 0.1%,
Ti: not less than 0.0001% and not more than 0.0030%,
S: not less than 0.0001% and not more than 0.0020%.
N: not less than 0.0001% and not more than 0.003%,
Ni: not less than 0.001% and not more than 0.2%, and
P: not less than 0.005% and not more than 0.05%,
with a balance consisting of Fe and impurities, wherein
a resistivity p at room temperature > 60 |a.ncm. and saturation magnetic flux
density Bs at room temperature > 1.945T are established, and
the components contained satisfy 3.5 < Si + (2/3) >- sol.Al + 0/5) x Mn <
4.25.
2. A method of manufacturing the non-oriented electrical steel sheet according
to Claim 1, including:
hot-rolling a slab containing the chemical components specified in Claim 1;
after the hot-rolling, applying hot-rolled-sheet annealing or self-annealing,
or without applying the hot-rolled-sheet annealing, and applying pickling in either
case;
applying cold-rolling once, or cold-rolling twice with intermediate
annealing applied between applications of cold-rolling; and
after the cold-rolling, applying final-annealing, and applying coating,
wherein
during the cold-rolling, the temperature of a steel sheet when the
cold-rolling starts is set to not less than 50°C and not more than 200°C, and a rate at
which the steel sheet passes through a first pass during rolling is set to not less than