DESCRIPTION
TITLE OF INVENTION: NON-ORIENTED ELECTRICAL STEEL
SHEET
TECHNICAL FIELD
[0001] The present invention relates to a nonoriented
electrical steel sheet suitable as a
material of a motor core, particularly a motor core
to be rotated at high speed and to be driven at high
frequency in an electric vehicle, a hybrid vehicle,
and the like.
BACKGROUND ART
[0002] In recent years, a lot of electric vehicles
and hybrid vehicles have become widespread, and as
for a driving motor used for these vehicles, highspeed
rotation has advanced and high-frequency
driving by an inverter has advanced. In order to
make the driving motor rotate at high speed and drive
at high frequency, a high-frequency core loss has
been required to be decreased in a non-oriented
electrical.steel sheet used as a motor core.
[0003] For decreasing the high-frequency core loss
in the non-oriented electrical steel sheet, it is
effective to decrease a sheet thickness and have high
resistivity by high alloying. However, when the
sheet thickness is decreased, in a steel maker,
productivity decreases, and in a motor maker, cost
for performing stamping and cost for laminating are
increased. Further, there are also problems such
that by thinning, core rigidity is decreased, fixing
- 1 -
the lamination becomes difficult, and so on. For
this reason, from a balance between a required core
loss property and cost, the sheet thickness of a
product is selected.
[0004] For increasing the resistivity by high
alloying, Si, Al, and Mn are generally used. However,
when Si and Al are added, there is a problem that the
hardness of the steel sheet increases and the steel
sheet becomes brittle, and thereby the productivity
deteriorates, and thus there are upper limits in
additive amounts. Further, in the case of Mn being
added, an increase width of the hardness of the steel
sheet is.small, but an effect of increasing the
resistivity is almost half as compared with Si and Al.
Further, in hot rolling, a problem of red shortness
is sometimes caused, and thus there is an upper limit
in an additive amount.
[0005] Thus, as another technique of increasing the
resistivity, in Patent Literature 1, for example,
there has been disclosed a technique of increasing
resistivity by adding 1.5% to 20% of Cr. An effect
of increasing the resistivity in the case of "Cr being
added is substantially equal to that of Mn, but as
long as 20% or less of Cr is added, the hardness of a
steel sheet does not increase so much and a concern
j of embrittlement is low. Further, unlike Mn, the
problem of red shortness is also small.
[0006] By the way, the driving motor of an electric
vehicle and a hybrid vehicle is used not only for
- 2 -
high-speed running, but also for low-speed hightorque
running at the time of start and at the time
of running uphill, and further it is conceivable that
the running speed is an intermediate speed between
them in a high-frequency running area where high
efficiency is required. For that reason, in the
electrical steel sheet for a motor core, not only the
decrease in core loss at high frequency but also a
decrease in core loss at low frequency is required.
[0007] However, as a result that present inventors
examined the disclosed technique in Patent Literature
described above in detail, in the technique in Patent
Literature 1, a core loss at a fixed frequency or
higher, for example, at 3000 Hz is good, but at low
frequency such as, for example, 800 Hz, there is a
problem that with an increase in additive amount of
Cr, the core loss deteriorates. Further, it was also
found that depending on the sheet thickness of a
product, the frequency at which the core loss starts
to deteriorate changes.
CITATION LIST
PATENT LITERATURE
[0008] Patent Literature 1: Japanese Laid-open Patent
Publication No. 2001-26823
Patent Literature 2: Japanese Laid-open Patent
Publication No. 2003-183788
Patent Literature 3: Japanese Laid-open Patent
• Publication No. 2002-317254
Patent Literature 4: Japanese Laid-open Patent
- 3 -
Publication No. 2002-115035
SUMMARY OF INVENTION
TECHNICAL PROBLEM
[0009] The present invention has been made in
consideration of the previously described problems,
and has an object to provide a non-oriented
electrical steel sheet excellent in core loss over
wide frequencies.
SOLUTION TO PROBLEM
[0010] Thus, as a result of repeated earnest
examinations for solving the above-described problems,
the present inventors obtained the knowledge in which
a ratio of Si, Al, and Cr in mass%, together with a
sheet thickness of a product, satisfies certain
expressions, and thereby the desired object is
achieved. That is, the gist and constitution of the
present invention are as follows.
[0011] (1) A non-oriented electrical steel sheet
includes:
C: 0.005 mass% or less; S: 0.003 mass% or less;
N: 0.003 mass% or less; Si: 2.0 mass% or more and
less than 4.5 mass%; Al: 0.15 mass% or more and less
than 2.5 mass%; and Cr: 0.3 mass% or more and less
than 5.0 mass%; and a balance being composed of Fe
and inevitable impurities; and a Cr-oxide-containing
layer having a thickness of not less than 0.01 //m nor
more than 0.5 n m on a surface side, in which
Expression 1 and Expression 2 below are further
satisfied.
- 4 -
10 mass% ^ 2[Si] + 2[A1] + [Cr] < 15 mass% ...
Expression 1
(2[A1] + [Cr])/2[Si] - 10t2 ^ 0.35 ... Expression
2
(Here, [Si], [Al], and [Cr] represent the Si content,
the Al. content, and the Cr content (mass%) of the
non-oriented electrical steel sheet respectively, and
t represents a sheet thickness (mm) of the nonoriented
electrical steel sheet.)
(2) The non-oriented electrical steel sheet
according to (1), in which
Expression 3 below is further satisfied..
(2[A1] + [Cr])/2[Si] - 5t2 ^ 0.35 ... Expression
3
(3) The non-oriented electrical steel sheet
according to (1) further includes:
Mn: not less than 0.2 mass% nor more than 1.5
mass % .
ADVANTAGEOUS EFFECTS OF INVENTION
[0012] According to the present invention, it is
possible to provide a non-oriented electrical steel
sheet excellent in core loss over wider frequencies.
DESCRIPTION OF EMBODIMENTS
[0013] Hereinafter, the present invention will be
explained in detail. First, there will be explained
reasons for limiting ranges of a chemical composition
in the present invention.
[0014] Si is an effective element for decreasing a
high-frequency core loss by increasing resistivity of
- 5 -
a steel sheet and decreasing an eddy current loss.
The Si content is set to 2 mass% or more and less
than 4.5 mass%. If the Si content is less than 2
mass%, the resistivity cannot be increased
sufficiently to thereby make it impossible to
sufficiently obtain an effect of decreasing the core
loss. On the other hand, Si decreases a saturation
magnetic flux density of the steel sheet, and thus if
the Si content exceeds 4.5 mass%, the saturation
magnetic flux density is decreased significantly and
a decrease in B50 (magnetic flux density at 5000 A/m
of excitation magnetizing force) being one of indexes
of material properties of the non-oriented electrical
steel sheet becomes significant.
[0015] Al is an effective element for decreasing the
high-frequency core loss by increasing the
resistivity of the steel sheet, similarly to Si, and
the Al content is set to 0.3 mass% or more and less
than 2.5 mass%. If the Al content is less than 0.3
mass%, the resistivity cannot be increased
i sufficiently to thereby make it impossible to
| sufficiently obtain an effect of decreasing the core
loss. On the other hand, Al decreases the saturation
\ magnetic flux density of the steel sheet, and thus if
the Al content exceeds 2.5 mass%, the saturation
magnetic flux density is decreased significantly and
the decrease in B50 becomes significant.
[0016] Cr has a smaller beneficial effect than Si
and Al, but is an effective element for decreasing
- 6 -
t
the high-frequency core loss by increasing the
resistivity of the steel sheet, and the Cr content is
set to 0.3 mass% or more and less than 5 mass%. If
the Cr content is less than 0.3 mass%, the
resistivity cannot be increased sufficiently to
thereby make it impossible to sufficiently obtain an
effect of decreasing the core loss. On the other
hand, Cr decreases the saturation magnetic flux
density of the steel sheet, and thus if the Cr
content exceeds 5 mass%, the saturation magnetic flux
density is decreased significantly and the decrease
in B50 becomes significant.
[0017] Further, in the relation of Si, Al, and Cr in
mass%, the condition of 10 mass% S= 2[Si] + 2[A1] +
[Cr] < 15 mass% is designed to be satisfied. Here,
[Si], [Al], and [Cr] represent the Si content, the Al
content, and the Cr content (mass%) of the nonoriented
electrical steel sheet respectively. If
2[Si] + 2[A1] + [Cr] is less than 10 mass?, the core
loss at 3000 Hz becomes too large. On the other hand,
if it exceeds 15 mass%, the saturation magnetic flux
density of the steel sheet is decreased significantly
and the decrease in B50 becomes significant.
Incidentally, the reason why the specific gravity of
Si and the specific gravity of Al are set to be twice
as large as that of Cr is based on the fact that the
beneficial effect of Cr is small.
[0018] The ratio of Si, Al, and Cr in mass%: (2[A1]
+ [Cr])/2[Si] is designed to satisfy certain
- 7 -
expressions to be explained below with respect to a
sheet thickness of a product and a targeted frequency.
As a result of repeated experiments conducted by
present inventors, it was found that even though the
Si content is increased, a hysteresis loss does not
deteriorate so much, but if the Al content and the Cr
content are increased, the hysteresis loss
deteriorates rapidly. As a result, it was found out
that even with the substantially equal resistivity
and sheet thickness, namely even with the
substantially equal eddy current loss, if the ratio
of (2[A1] + [Cr])/2[Si] is increased, the core loss
deteriorates, namely the hysteresis loss deteriorates.
[0019] Further, as a result of a further experiment,
this tendency became more significant in a lowfrequency
region where the proportion of the
hysteresis loss increases, or even in a highfrequency
region when the sheet thickness was
decreased and the eddy current loss was decreased.
It is conceivable that the eddy current loss is
proportional to the square of the frequency and the
square of the sheet thickness and the hysteresis loss
is proportional to the first power of the frequency
but does not rely on the sheet thickness. Thus, the
following expressions were derived based on
experimental data.
(2[A1] + [Cr])/2[Si] - 10t2 ^ 0.35
Here, t represents the sheet thickness (mm) of
the non-oriented electrical steel sheet being the
- 8 -
product.
[0020] Further, in order to improve the core loss in
a lower frequency region (for example, 400 Hz), it is
preferred that the condition of the following
expression should be designed to be further satisfied.
(2[A1] + [Cr])/2[Si] - 5t2 ^ 0.35
[0021] C, S, and N are impurity elements for the
non-oriented electrical steel sheet of the present
invention, and the smaller they are, the more
desirable it is.
[0022] C is an element that precipitates in the
steel sheet as carbide to make a growth potential of
crystal gains and the core loss deteriorate. Thus,
the C content is set to 0.005 mass% or less. If the
C content exceeds 0.005 mass%, the growth potential
of crystal grains deteriorates and the core loss
deteriorates. Further, for suppressing magnetic
aging, the C content is preferably set to 0.003 mass%
or less. Its lower limit is not limited in
particular, but it is difficult to set the lower
limit to 0.001 mass? or less in a normal
manufacturing method.
[0023] S is an element that precipitates in the
steel sheet as sulfide to make the growth potential
of crystal gains and the core loss deteriorate. Thus,
the S content is set to 0.003 mass% or less. If the
S content exceeds 0.003 mass%, the growth potential
of crystal grains deteriorates and the core loss
deteriorates. Its lower limit is not limited in
| - 9 -
t
particular, but it is difficult to set the lower
limit to 0.0005 mass% or less in a normal
manufacturing method.
[0024] The N content is set to 0.003 mass% or less.
If the N content exceeds 0.003 mass%, a blistershaped
surface defect, which is called a blister, is
caused. Its lower limit is not limited in particular,
but it is difficult to set the lower limit to 0.001
mass% or less in a normal manufacturing method.
[0025] Further, other elements may also be contained
according to the object.
In the case of Mn being contained, the Mn content
is preferably set to 1.5 mass% or less. Although the
beneficial effect of Mn is also small, Mn increases
the resistivity of the steel sheet, but if the Mn
content exceeds 1.5 mass%, there is a possibility
that the steel sheet becomes brittle. Its lower
limit is not limited in particular, but the lower
limit is further preferably 0.2 mass% or more from
the viewpoint of suppressing fine precipitation of
sulfide.
[0026] Besides, well-known additive elements are
allowed to be contained for the purpose of improving
the magnetic property and the like. As this example,
0.20 mass% or less of at least one type of Sn, Cu, Ni,
and Sb may also be contained.
[0027] Next, there will be explained a manufacturing
method of the non-oriented electrical steel sheet
having the characteristics as above.
- 10 -
[0028] First, a molten steel made of the same
components as those of the product explained above is
cast to make a slab, and the made slab is reheated
and is subjected to hot rolling, to thereby obtain a
hot-rolled sheet. Incidentally, in making the slab,
a thin slab may be made by a rapid cooling
solidification method, or a thin steel sheet may also
be cast directly to thereby obtain a hot-rolled sheet.
[0029] Next, on the obtained hot-rolled sheet,
normal pickling is performed, and then cold rolling
is performed, to thereby obtain a cold-rolled sheet.
Incidentally, hot-rolled sheet annealing may also be
performed before performing the pickling, for the
purpose of improving the magnetic property. The hotrolled
sheet annealing may be continuous annealing or
may also be batch annealing, and is performed at a
temperature and for a period of time allowing a
crystal grain diameter suitable for the improvement
of the magnetic property to be obtained.
[0030] The cold rolling is normally performed in
reverse or in tandem, but a reverse mill such as a
Sendzimir mill makes it possible to obtain the higher
magnetic flux density, and thus is preferred.
Further, if Si and Al are too large, the steel sheet
becomes brittle, and thus as measures against brittle
fracture, warm annealing may also be performed. Then,
by the cold rolling, the hot-rolled sheet is rolled
to the sheet thickness of the product. From the
viewpoint of decreasing the high-frequency core loss,
- 11 -
I
the thickness is preferably set to 0.1 mm 0.35 mm.
Further, in the cold rolling, intermediate annealing
may also be performed one time or more.
[0031] The hot-rolled sheet is cold rolled to the
sheet thickness of the product, and then is subjected
to finish annealing. In the finish annealing, a
sufficient temperature for making crystal grains
recrystallized and grain-grown is needed, and the
finish annealing is normally performed at 800°C to t
1100°C. By this finish annealing, a Cr oxide layer is
formed on the surface of the steel sheet.
[0032] The Cr oxide is thin and has an extremely
dense structure, and it is conceivable that when the
Cr oxide layer is formed on the surface of the steel
sheet, invasion of oxygen thereafter is prevented and
thereby internal oxidation of Si and Al is suppressed.
Si and Al in the steel sheet are likely to be
oxidized, and thus if at high temperature, oxygen is
diffused in the steel sheet and thereby the internal
oxidation occurs, domain wall displacement is
prevented and the hysteresis loss is deteriorated.
Further, if the internal oxidation occurs, due to the
existence of a nonmagnetic oxide layer, an effective
cross-sectional area through which magnetic flux can
pass is decreased to thereby increase the magnetic
flux density and also deteriorate the eddy current
loss. Further, at high frequency, the magnetic flux
concentrates in the vicinity of a surface layer of
the steel sheet by the skin effect, so that the
- 12 -
above-described effect becomes more significant.
[0033] In consideration of the above, the thickness
of the Cr oxide layer formed on the surface of the
steel sheet is designed to be not less than 0.01 jum
nor more than 0.5 ju m. If the thickness of the Cr
oxide layer is less than 0.01 (im, the effect of
preventing the invasion of oxygen to thereby suppress
the internal oxidation of Si and Al is insufficient.
Further, if the thickness of the Cr oxide layer
exceeds 0.5 urn, an adverse effect on the magnetic
• property starts to appear. In order to set the
thickness of the Cr oxide layer to not less than 0.01
ju m nor more than 0.5 jum, in the finish annealing
after the cold rolling, an oxygen potential is set to
a low-oxygen potential in the entire annealing, and
even at the time of increasing the temperature, the
oxygen potential is set to a low-oxygen potential.
For example, at 300°C to 500°C at the time of
increasing the temperature, the oxygen potential is
set to PH2O/PH2 ^ 10"3.
[0034] After the finish annealing, normally, a film
for the purpose of insulation is applied to be baked.
As long as the film is insulative, it does not impede
the effect of the. present invention even if it is
totally organic, totally inorganic, or a mixture of
an organic matter and an inorganic matter, and thus
the film is not limited in particular.
[Example]
[0035] Next, t h e r e w i l l be e x p l a i n e d e x p e r i m e n ts
- 13 -
conducted by the present inventors. Conditions and
so on in these experiments are examples employed for
confirming the applicability and effects of the
present invention, and the present invention is not
limited to these examples.
[0036] (Example 1)
First, hot-rolled sheets each containing C: 0.002
mass%, S: 0.002 mass%, N: 0.002 mass%, and Mn: 0.3
mass%, and each having a composition of Si, Al, and
Cr shown in Table 1 below were prepared and were each
subjected to pickling to be cold rolled, to thereby
obtain cold-rolled sheets each having a thickness of
0.25 mm. Next, under the conditions shown in Table 1,
an oxygen potential was controlled, finish annealing
was performed at 1000°C, and then non-oriented
electrical steel sheets were obtained.
[0037] [Table 1]
TABLE 1
FINISH FINISH THICKNESS
STEEL 2rSil+2rAl1 SHEET ANNEALING ANNEALING °F Cr
NO COMPONENT lblJ lAi) sncci rtWHCfti.iHt, OXIDE
, . + Cr] THICKNESS > 300~ DURING
(massl) -n n < r SOAKTNC
LAYER ON
___^__^___ 500C SOAKING SURFACE
Si I Al I Cr
mm PH2Q/PH2 PH20/PH2 p. m
1 3.00 1.00 2.00 10 0.25 3*10"' 1*10"' 0.1
2 3.00 1.002.00 10 0.25 3*1 0"3 1*10'" 0.8
3 3.00 1.95 0.10 10 0.25 3*10"' 1*10"4 UNDETECTABLE
[0038] Next, a sample for magnetic measurement was
cut out of each of the obtained non-oriented
electrical steel sheets, of which a core loss
W10/3000 at 3000 Hz and 1 T and a core loss W10/800
I
- 14 -
j
at 800 Hz and 1 T were measured. Further, a sample
for observation was cut out and a cross section of
each of the non-oriented electrical steel sheets was
observed. As an observation method, by using a SEM
and GDS, the thickness of a Cr oxide layer was
measured. As a result, the thickness of each of the
Cr oxide layers was as shown in Table 1. Further,
samples No. 1 to No. 3 each resulted in 2[Si] + 2[Al]
+ [Cr] = 10 and (2[A1] + [Cr])/2[Si] - 10t2 = 0.053.
In Table 2 below, measurement results of the core
loss are shown.
[0039] [Table 2]
TABLE 2
lwiO/3000 |wi0/800 INOTE I
N ° W/kg W/kg
PRESENT
1 260 29.6 INVENTION
RANGE
OUTSIDE
2 267 31.3 INVENTION
RANGE
OUTSIDE
3 266 30.9 INVENTION
j | | RANGE I
[0040] As shown in Table 2, in the sample No. 1
being the present invention example, the core loss
was excellent at both the frequencies of 3000 Hz and
800 Hz. On the other hand, the sample No. 2 being
the comparative example had the same components as
those of the. sample No. 1, but had the high oxygen
potential at th,e time of increasing the temperature
in the finish annealing, and thus the thickness of
- 15 -
4
the Cr oxide layer became 0.8 /z m and the core loss
W10/3000 and the core loss W10/800 both became larger
than those in the sample No. 1. Further, it is
inferred that the sample No. 3 had the small Cr
content, and thus the Cr oxide layer was undetectable
and the thickness was less than 0.01 urn. As a result,
it is inferred that an internal oxide layer of Si and
Al was generated, and the core loss W10/3000 and the
core loss W10/800 both became larger than those in
the sample No. 1.
[0041] (Example 2)
First, hot-rolled sheets each containing C: 0.002
mass?, S: 0.002 mass%, N: 0.002 mass%, and Mn: 0.3
mass%, and having a component A to a component L of
Si, Al, and Cr shown in Table 3 below were prepared
and were each subjected to pickling to be cold rolled,
to thereby obtain cold-rolled sheets each having a
thickness of 0.15 mm to 0.30 mm. Next, in a dry
hydrogen atmosphere, finish annealing was performed
at 1000°C. An oxygen potential PH2O/PH2 at that time
was set to 3 X 10-4 at 300 to 500°C at the time of
increasing the temperature, and was set to 1 X 10"4
during soaking, and then non-oriented electrical
steel sheets were obtained.
• [0042] [Table 3]
- 16 -
1
TABLE 3
COMPONENT STEEL COMPONENT (ma s s % )
No Si Al Cr 2fSi]+2[Al]+[Cr]
A 3.00 1.25 0.50 9
B 3.00 1.00 1.00 9
C 2.50 1.25 1.50 9
D 3.501.001.00 10
E 3.00 1.00 2 .00 10
F 3.00 1.50 1 .00 10
G 2.002.002.00 10
H 3.00 2.00 1 .00 11
I 3.501.501.00 11
J 4 .00 1.00 1.00 11
K 3.50 1.50 2.00 12
L 4.00 1.00 2.00 12
[0043] Next, a sample for magnetic measurement was
cut out of each of the obtained non-oriented
electrical steel sheets, of which the core loss
W10/3000 at 3000 Hz and 1 T, the core loss W10/800 at
800 Hz and 1 T, and a core loss W10/400 at 400 Hz and
1 T were measured. Further, by procedures similar to
those in Example 1, the thickness of each of Cr oxide
layers was measured, resulting in that the thickness
of the Cr oxide layer fell within a range of 0.01 nm
to 0.5 /im in all samples. First, measurement results
of the core loss W10/3000 and the core loss W10/800
are shown in Table 4 and Table 5 below. Incidentally,
(2[A1] + [Cr])/2[Si] - 10t2 of each of the samples was
calculated, resulting in that results shown Table 4
and Table 5 below were obtained.
[0044] [Table 4]
- 17 -
TABLE 4
NO C 0 M P ° N E N T
2!A1] THICKNESS W 1 ° ^ ° 0 0 l C ? » / 2 ^f*00 NOTE
No +[Cr] mm W/kg [S^ W/kg
=_ _ . . . OUTSIDE
101 A 9 0.15 170 0.28 21.1 INVENTION
RANGE
OUTSIDE
102 B 9 0.15 170 0.28 21.1 INVENTION
RANGE
OUTSIDE
103 C 9 0.15 172 0.58 22.2 INVENTION
' RANGE
PRESENT
104 D 10 0.15 158 0.20 20.0 INVENTION
RANGE
OUTSIDE
105 E 10 0.15 160 0.44 20.9 INVENTION
; ; RANGE
OUTSIDE
106 F 10 0.15 160 0.44 20.9 INVENTION
RANGE
OUTSIDE
107 G. 10 0.15 167 1.28 24.1 INVENTION
RANGE
OUTSIDE
108 H 11 0.15 153 0.61 20.8 INVENTION
RANGE
PRESENT
109 I 11 0.15 150 0.35 19.8 INVENTION
RANGE
PRESENT
110 J 11 0.15 149 0.15 19.1 INVENTION
. RANGE
OUTSIDE
111 K 12. 0.15 144 0.49 20.0 INVENTION
^ RANGE
PRESENT
112 L 12 0.15 142 0.28 19.0 INVENTION
_ RANGE
OUTSIDE
113 A 9 0.20 223 0.10 25.6 INVENTION
RANGE
OUTSIDE
114 B 9 0.20 223 0.10 25.6 INVENTION
RANGE
OUTSIDE
115 C 9 0.20 225 0.40 26.8 INVENTION
RANGE
PRESENT
116 D 1-0 0.20 205 0.03 24.0 INVENTION
RANGE
PRESENT
117 E 10 0.20 207 0.27 25.0 INVENTION
| J I I | RANGE I
- 18 -
[ I I 1 I [ I 1 PRESENT I
118 F 10 0.20 207 0.27 25.0 INVENTION
; RANGE
OUTSIDE
119 G 10 0.20 215 1.10 r 28.1 INVENTION
I RANGE
OUTSIDE
120 H 11 0.20 195 0.43 25.2 INVENTION
RANGE
PRESENT
121 I 11 0.20 193 0.17 23.5 INVENTION
RANGE
PRESENT
122 J 11 0.20 191 -0.03 22.8 INVENTION
RANGE
PRESENT
123 K 12 0.20 183 0.31 23.2 INVENTION
RANGE
PRESENT
124 L 12 0.20 181 0.10 22.4 INVENTION
_ _ RANGE
OUTSIDE
125 A 9 0.25 283 -0.13 30.8 INVENTION
RANGE
OUTSIDE
126 B 9 0.25 283 -0.13 30.8 INVENTION
RANGE
OUTSIDE
127 C 9 0.25 285 0.18 31.9 INVENTION
RANGE
PRESENT
128 D 10 0.25 258 -0.20 28.7 INVENTION
: RANGE
PRESENT
129 E 10 0.25 260 0.04 29.6 INVENTION
; RANGE
PRESENT
130 F 10 0.25 260 0.04 29.6 INVENTION
RANGE
OUTSIDE
131 G 10 0.25 268 0.88 32.8 INVENTION
RANGE
PRESENT
132 H 11 0.25 243 0.21 28.7 INVENTION
RANGE
PRESENT
133 I 11 0.25 240 -0.05 27.7 INVENTION
. . | | I I J | RANGE
[0045] [Table 5]
- 19 -
TABLE 5
I I I I I / o f n 1 1 + ! I 1
NO COMPONENT ' ' THICKNESS W 1 ° ^ ° 0 0 ' " V / 2 " " A 8 0 0 NOTE
No +[(, r ] mm W/kg [Si)2 W/kg
" PRESENT
134 J 11 0.25 239 -0.25 27.0 INVENTION
RANGE
PRESENT
135 K 12 0.25 226 0.09 27.1 INVENTION
RANGE
PRESENT
136 L 12 0.25 224 -0.13 26.2 INVENTION
RANGE
OUTSIDE
137 A 9 0.30 348 -0.40 36.4 INVENTION
. RANGE
OUTSIDE
138 B 9 0.30 348 -0.40 36.4 INVENTION
RANGE
OUTSIDE
139 C 9 0.30 350 -0.10 37.6 INVENTION
" RANGE
PRESENT
140 D 10 0.30 316 -0.47 33.8 INVENTION
RANGE
PRESENT
141 E 10 0.30 318 -0.23 34.7 INVENTION
RANGE
PRESENT
142 F 10 0.30 318 -0.23 34.7 INVENTION
RANGE
OUTSIDE
143 G 10 0.30 325 0.60 37.9 INVENTION
RANGE
PRESENT
144 H 11 0.30 294 -0.07 33.4 INVENTION
RANGE
PRESENT
145 I 11 0.30 292 -0.33 32.4 INVENTION
; • RANGE
PRESENT
146 J 11 0.30 290 -0.53 31.6 INVENTION
[ • ; RANGE
PRESENT
147 K 12 0.30 272 -0.19 31.3 INVENTION
RANGE
PRESENT
148 L 12 0.30 270 -0.40 30.5 INVENTION
I J J |_ | | | RANGE I
[0046] As shown in Table 4 and Table 5, the samples
with the components A to C being the comparative
- 20 -
example each satisfied 2[Si] + 2[A1] + [Cr] < 10
mass%, and thus as compared with the ones each having
the same sheet thickness, the core loss W10/3000 was
large. The samples with the components D to L each
satisfied 2[Si] + 2[A1] + [Cr] ^ 10 mass%, and as
compared with the samples with the components A to C
each having the same sheet thickness, the core loss
W10/3000 was small. However, in the samples each
satisfying (2[A1] + [Cr])/2[Si] - 10t2 > 0.35, the '
core loss W10/800 was large as compared with the ones
each having the same sheet thickness.
[0047] In Table 6 and Table 7 below, measurement
results of the core loss W10/3000 and the core loss
W10/400 are shown. Incidentally, (2[A1] +
[Cr])/2[Si] - 5t2 of each of the samples was
calculated, resulting in that results shown in Table
6 and Table 7 below were obtained.
[0048] [Table 6]
- 21 -
4
TABLE 6
NO COMPONENT \ ^ +
T H^ESS ^J"?0 0 0 ^ J . ' / ' V1°'4°° NOTE
No + [ C r ] mm W/kg [Si] W/kg
_ _ _ _ , =_ , OUTSIDE
101 A 9 0.15 170 0.39 8.6 INVENTION
RANGE
OUTSIDE
102 B 9 0.15 170 0.39 8.6 INVENTION
RANGE
OUTSIDE
103 C 9 0.15 172 0.69 9.2 INVENTION
RANGE
PRESENT
104 D 10 0.15 158 0.32 8.3 INVENTION
RANGE
OUTSIDE
105 E 10 0.15 160 0.55 8.7 INVENTION
. RANGE
OUTSIDE
106 F 10 0.15 160 0.55 8.7 INVENTION
RANGE
OUTSIDE
107 G 10 0.15 167 1.39 10.3 INVENTION
RANGE
OUTSIDE
108 H 11 0.15 153 0.72 8.9 INVENTION
RANGE
OUTSIDE
109 I 11 0.15 150 0.46 8.4 INVENTION
RANGE
PRESENT
110 J 11 0.15 149 0.26 8.0 INVENTION
RANGE
OUTSIDE
111 K 12 0.15 144 0.60 8.5 INVENTION
RANGE
OUTSIDE
112 L 12 0.15 142 0.39 8.3 INVENTION
^ ___ RANGE
OUTSIDE
113 A 9 0.20 223 0.30 9.9 INVENTION
. RANGE
OUTSIDE
114 B 9 0.20 223 0.30 9.9 INVENTION
; RANGE
OUTSIDE
115 C 9 0.20 225 0.60 10.4 INVENTION
RANGE
PRESENT
116 D 10 0.20 205 0.23 9.2 INVENTION
[ RANGE
OUTSIDE
117 E 10~ 0.20 207 0.47 9.8 INVENTION
I I I I |_ L | RANGE |
- 22 -
I I I I I I I I 0UTSIDE I
118 F 10 0.20 207 0.47 9.8 INVENTION
RANGE
OUTSIDE
119 G 10 0.20 215 1.30 11.4 INVENTION
RANGE
OUTSIDE
120 H 11 0.20 195 0.63 9.9 INVENTION
RANGE
OUTSIDE
121 I 11 0.20 193 0.37 9.4 INVENTION
RANGE
PRESENT
122 J 11 0.20 191 0.18 9.0 INVENTION
RANGE
OUTSIDE
123 K 12 0.20 183 0.51 9.4 INVENTION
RANGE
PRESENT
124 L 12 0.20 181 0.30 9.0 INVENTION
; _____ RANGE
OUTSIDE
125 A 9 0.25 283 0.19 11.3 INVENTION
^ RANGE
OUTSIDE
126 B 9 0.25 283 0.19 11.3 INVENTION
RANGE
OUTSIDE
127 C 9 0.25 285 0.49 11.8 INVENTION
RANGE
PRESENT
128 D 10 0.25 258 0.12 10.6 INVENTION
RANGE
PRESENT
129 E 10 0.25 260 0.35 11.1 INVENTION
RANGE
PRESENT
130 F 10 0.25 260 0.35 11.1 INVENTION
RANGE
OUTSIDE
131 G 10 0.25 268 1.19 12.7 INVENTION
RANGE
OUTSIDE
132 H 11 0.25 243 0.52 11.6 INVENTION
RANGE
PRESENT
133 I 11 0.25 240 0.26 10.5 INVENTION
| J j RANGE
[0049] [Table 7]
- 23 -
TABLE 7
_______
No COMPONENT 2 I S i ' +
T H ^ S S "10/3000 [ C r ] ) / 2 " 0 / 4 0 0 - NQ__
No +[_ r ] mm W/kg [Si] W/kg
PRESENT
134 J 11 0.25 239 0.06 10.1 INVENTION
; RANGE
OUTSIDE
135 K 12, 0.25 226 0.40 10.4 INVENTION
RANGE
PRESENT
136 L 12 0.25 224 0.19 10.0 INVENTION
RANGE
OUTSIDE
137 A 9 0.30 348 0.05 12.8 INVENTION
RANGE
OUTSIDE
138 B 9 0.30 348 0.05 12.8 INVENTION
RANGE
OUTSIDE
139 C 9 0.30 350 0.35 13.4 INVENTION
RANGE
PRESENT
140 D 10 0.30 316 -0.02 12.0 INVENTION
RANGE
PRESENT
141 E 10 0.30 318 0.22 12.5 INVENTION
RANGE
PRESENT
142 F 10 0.30 318 0.22 12.5 INVENTION
RANGE
OUTSIDE
143 G 10 0.30 325 1.05 14.1 INVENTION
RANGE
OUTSIDE
144 H 11 0.30 294 0.38 12.7 INVENTION
RANGE
PRESENT
145 I 11 0.30 292 0.12 11.8 INVENTION
RANGE
PRESENT
146 J 11 0.30 290 -0.08 11.4 INVENTION
._ RANGE
PRESENT
147 K 12 0.30 272 0.26 11.6 INVENTION
RANGE
PRESENT
148 L 12 0.30 270 0.05 11.2 INVENTION
I I | [__ | 1 RANGE 1
[0050] As shown in Table 6 and Table 7, as for each
of the components D to L, 2 [Si] '+ 2[A1] + [Cr] __ 10
- 24 -
mass% was satisfied, but in the samples each
satisfying (2[A1] + [Cr])/2[Si] - 5t2 > 0.35, the core
loss W10/400 was large as compared with the ones each
having the same sheet thickness.
INDUSTRIAL APPLICABILITY
[0051] According to the present invention, it is
possible to utilize a non-oriented electrical steel
sheet as a material of a motor core to be rotated at
high speed and to be driven at high frequency in an
electric vehicle, a hybrid vehicle, and the like.
- 25 -

CLAIMS
[Claim 1] A non-oriented electrical steel sheet
comprising:
C: 0.005 mass% or less; S: 0.003 mass% or less;
N: 0.003 mass% or less; Si: 2.0 mass% or more and
less than 4.5 mass%; Al: 0.15 mass% or more and less
than 2.5 mass%; and Cr: 0.3 mass% or more and less
than 5.0 mass%; and a balance being composed of Fe
and inevitable impurities; and a Cr-oxide-containing
layer having a thickness of not less than 0.01 p. m nor
more than 0.5 n m on a surface side, wherein
Expression 1 and Expression 2 below are further
satisfied.
10 mass? ^ 2[Si] + 2[A1] + [Cr] < 15 mass% ...
Expression 1
(2[A1] + [Cr])/2[Si] - 10t2 ^ 0.35 ... Expression
2
(Here, [Si], [Al], and [Cr] represent the Si content,
the Al content, and the Cr content (mass%) of the
non-oriented electrical steel sheet respectively, and
t represents a sheet thickness (mm) of the nonoriented
electrical steel sheet.)
[Claim 2] The non-oriented electrical steel sheet
according to claim 1, wherein
Expression 3 below is further satisfied.
(2[A1] + [Cr])/2[Si] - 5t2 ^ 0.35 ... Expression
3
[Claim 3] The non-oriented electrical steel sheet
according to claim 1, further comprising:
- 26 -
Mn: not less than 0.2 mass% nor more than 1.5
. mass%.