DESCRIPTION
TITLE OF INVENTION: NON-ORIENTED ELECTRICAL STEEL
SHEET
TECHNICAL FIELD
[0001] The present invention relates to a high-grade
non-oriented electrical steel sheet used for a highfrequency
usage such as an iron core of a motor, and
to a non-oriented electrical steel sheet to make
electric equipment more efficient and contribute to
energy saving by reducing energy loss, especially
excellent in core loss after a strain relief
annealing. This application is based upon and claims
the benefit of priority from Japanese Patent
Application No. 2012-29884, filed on February 14,
2012; the entire contents of all of which are
incorporated herein by reference.
BACKGROUND ART
[0002] In recent years, energy saving is required
from a point of view of preventing global warming,
and further reduction in power consumption is
required in fields such as a motor of an air
conditioner and a main motor of an electric vehicle.
These motors are often used in high rotation, and
therefore, improvement in core loss at a region of
400 Hz to 800 Hz being higher frequency than 50 Hz to
60 Hz being a conventional commercial frequency is
required for a non-oriented electrical steel sheet
(hereinafter, there is a case when it is described as
a "steel sheet") to be a motor material.
- 1 -
[0003] As a measure to improve the core loss at the
high-frequency region of the non-oriented electrical
steel sheet, it is generally performed to increase
electrical resistance by increasing contents of Si
and Al as described in, for example, Patent
Literature 1. Note that recently, there is a case
when an alloy raw material of Si and Al whose Ti
content is high is used as a cheap alloy raw material
to reduce cost.
[0004] According to the increase of the contents of
Si and Al, Ti having high affinity with these
elements is inevitably contained in the alloy raw
material, and therefore, Ti is inevitably mixed into
the steel sheet. When Ti in the steel sheet is 0.001
mass% or more, a number of fine Ti inclusions whose
diameters are approximately several dozen nm such as
TiN, TiS, TiC are generated in the steel sheet. The
fine Ti inclusions in the steel sheet may disturb a
growth of crystal grains at an annealing time of the
steel sheet, and deteriorates magnetic properties.
[0005] Accordingly, it is necessary to reduce the Ti
inclusions in the steel sheet as much as possible.
One of measures of the above is to use the alloy raw
material whose Ti content being an impurity is small.
However, there is a problem to incur a cost increase
of the alloy raw material if this measure is taken.
Besides, it is also one of the measures to reduce the
Ti inclusions by decreasing N, S and C in the steel
sheet, and it is possible with current technology to
- 2 -
enough decrease S and C by a vacuum degassing
treatment and so on. However, the treatment for a
long time is necessary to decrease S and C in the
steel sheet, and productivity is thereby lowered.
Besides, it is also conceivable to enhance sealing of
a refining vessel not to mix N into molten steel, but
it incurs the cost increase caused by the enhancement
of the sealing, and further, there is a problem that
the mixture of N into the molten steel is inevitable
even if the treatment as stated above is performed.
CITATION LIST
PATENT LITERATURE
[0006] Patent Literature 1: Japanese Laid-open
Patent Publication No. 2007-16278
Patent Literature 2: Japanese Laid-open Patent
Publication No. 2005-336503
Patent Literature 3: Japanese Examined Patent
Application Publication No. 54-36966
Patent Literature 4: Japanese Laid-open Patent
Publication No. 2006-219692
SUMMARY OF INVENTION
TECHNICAL PROBLEM
[0007] An object of the present invention is to
provide a non-oriented electrical steel sheet capable
of being manufactured with low cost and high
productivity by a manufacturing process in
conventional means, and excellent in crystal grain
growth potential at an annealing time and whose core
loss at high-frequency is good.
SOLUTION TO PROBLEM
[0008] The gist of the present invention to solve
the above-stated problems is as described below.
(1) A non-oriented electrical steel sheet,
containing:
C: 0.01 mass% or less,
Si: 1.0 mass% or more and 3.5 mass% or less,
Al: 0.1 mass% or more and 3.0 mass% or less,
Mn: 0.1 mass% or more and 2.0 mass% or less,
P: 0.1 mass% or less,
S: 0.005 mass% or less,
Ti: 0.001 mass% or more and 0.01 mass% or less,
N: 0.005 mass% or less, and
Y: more than 0.05 mass% and 0.2 mass% or less,
with a balance being iron and inevitable
impurities.
(2) The non-oriented electrical steel sheet according
to (1), further containing elements of group(s) of
one type or two types or more selected from:
a first group of one type or two types selected
from a group consisting of Cu: 0.5 mass% or less, and
Cr: 2 0 raass% or less;
a second group of one type or two types selected
from a group consisting of Sn and Sb for a total of
0.3 mass% or less;
a third group of Ni: 1.0 mass% or less; and
a fourth group of Ca: 0.01 mass% or less.
ADVANTAGEOUS EFFECTS OF INVENTION
[0009] The non-oriented electrical steel sheet
- 4 -
according to the present invention is excellent in
the crystal grain growth potential at the annealing
time and the core loss at the high-frequency region
because the amount of fine Ti inclusions in the steel
sheet is small. Further, it is possible to
manufacture with low cost and high productivity, and
therefore, it is possible to contribute to energy
saving by improving motor characteristics.
BRIEF DESCRIPTION OF DRAWINGS
[0010] [Fig. 1] Fig. 1 is a view illustrating a
relationship among a Y content in a steel sheet, a
content of Ti inclusions of a production sample after
a strain relief annealing, and a crystal grain
diameter.
DESCRIPTION OF EMBODIMENTS
[0011] When a proper amount of Y is added to a nonoriented
electrical steel sheet, generation of Ti
inclusions such as fine TiN, TiS, TiC in the steel
sheet is suppressed, and a number density of these Ti
inclusions remarkably decreases. It becomes clear as
a result of hard examinations that suppression of a
crystal grain growth of steel is thereby released and
a crystal grain growth potential is largely improved.
Note that Y represents yttrium, being an element
having atomic number 39, and is a kind of a rareearth
element.
[0012] Hereinafter, effects to add Y are described
in detail.
A laboratory experiment using a vacuum melting is
- 5 -
performed by the following procedure. At first,
various kinds of molten steels containing C: 0.0019
mass% to 0.0032 mass%, Si: 2.1 mass% to 3.1 mass%,
Al: 0.2 mass% to 0.4 6 mass%, Mn: 0.3 mass% to 0.5
mass%, P: 0.03 mass% to 0.05 mass%, S: 0.0022 mass%
to 0.0035 mass%, Ti: 0.002 mass% to 0.005 mass%, and
N: 0.0018 mass% to 0.0033 mass% as basic components,
and changing a component within a range of Y: "0"
(zero) mass% to 0.25 mass% are melted. Each of them
is solidified into an ingot, and thereafter,
experiments are performed in a sequence of a hot
rolling, a hot-rolled sheet annealing, a cold rolling,
a finish annealing, and a strain relief annealing as
the laboratory experiment to manufacture a production
sample whose thickness is 0.35 mm. Next,
examinations of inclusions and crystal grains are
performed by the following methods.
[0013] At first, an examination method of the
inclusions is described. The sample is first
polished from a surface thereof to an appropriate
thickness to make the surface of the sample a mirror
surface. After a later-described etching is
performed, the inclusions are examined by using a
field-emission type scanning electron microscope and
an energy dispersive spectroscopic analyzer. In this
examination, a composition of the inclusion is
analyzed and the number of inclusions, in a unit -
observation area is counted as for the inclusions
whose diameters are 10 nm to 500 nm. It is converted
into a number density of the inclusions per unit
volume of the sample according to a formula of DeHoff
illustrated in ASTM E127: Annual Book of ASTM
standards Vol. 03.03, (1995). Note that the abovestated
method is an example, and a replica or a thin
film may be created from the sample to examine, or a
transmission electron microscope may be used.
[0014] As an etching method, for example, a method
of Kurosawa, and so on described in (Fumio Kurosawa,
Isao Taguchi, Ryutaro Matsumoto: The Journal of the
Japan Institute of Metals, 43(1979), p.1068) is used.
Electrolytic etching is performed for the sample in
non-water-soluble solvent liquid according to this
method, and the inclusions are extracted by
dissolving only the steel while remaining the
inclusions. Besides, when the crystal grain diameter
is measured, a cross section of the sample is mirror
polished, nital etching is performed to exhibit the
crystal grain, and an average crystal grain diameter
is measured.
[0015] Fig. 1 is a view illustrating a relationship
among an Y content, an amount of Ti inclusions, and
the crystal grain diameter in a production sample
according to the above-stated experiment. Note that
in Fig. 1, a relationship between the Y content and
the amount of the Ti inclusions is represented by a
dotted line, and a relationship between the Y content
and the crystal grain diameter is represented by a
solid line. Here, there are TiN, TiS and Tie in
- 7 -
kinds of the observed Ti inclusions. These Ti
inclusions are each different in a temperature in
which they are generated, where TiN is generated at
1000°C or more, TiS is generated at 900°C or more and
less than 1000°C, and TiC is generated at 700°C or
more and 800°C or less. These Ti inclusions are
generated a lot as fine inclusions whose diameters
are approximately several dozen nm while generally
using a grain boundary, dislocation, and so on as a
precipitation site, and disturb a growth of the
crystal grain of the steel by pinning it.
[0016] As a result of the experiment, it becomes
obvious that when more than 0.05 mass% of Y is
contained in the steel sheet, the number density of
the Ti inclusions in the production sample remarkably
decreases and growth potential of the crystal grain
of the steel is drastically improved.
[0017] Here, when Y is added, Y inclusions of an Y
oxide and an Y oxysulfide whose diameters are several
hundred nm are observed in the steel sheet, but an
amount of Y existing as the Y inclusions as stated
above does not exceed 0.01 mass%. Accordingly, when
Y is added for more than 0.01 mass%, it is estimated
that Y is solid-dissolved in the steel sheet. As the
Y content in the steel sheet exceeds 0.01 mass% and
the amount of Y estimated to be solid-dissolved
increases, the number density of the Ti inclusions
decreases monotonously. When the Y content in the
steel sheet exceeds 0.05 mass%, it becomes obvious
that the number density of the Ti inclusions in the
steel sheet becomes remarkably small. Note that a
mechanism in which the Ti inclusions are suppressed
by Y is not clear, but it is conceivable that when Y
is solid-dissolved in the steel sheet, an activity of
Ti in the steel sheet decreases and the generation of
the Ti inclusions is suppressed. Note that this
effect is peculiar to Y, and the effect as stated
above cannot be seen in the other rare-earth elements
[0018] It is observed that a required range of the Y
content in the steel sheet is more than 0.05 mass%
from the above-stated experiment to remarkably
decrease the Ti inclusions. On the other hand, when
the Y content in the production sample exceeds 0.2
mass%, segregation of Y at the grain boundary becomes
remarkable, the grain boundary is embrittled, and
scabs occur at a surface of the production sample.
[0019] Accordingly, it is important to suppress a
grain boundary segregation of Y by setting the Y
content in the steel sheet at 0.2 mass% or less while
enough suppressing the Ti precipitate by making the
steel sheet contain Y more than 0.05 mass% so as to
manufacture a non-oriented electrical steel sheet
whose crystal grain growth potential is good,
magnetic properties are good, and a surface quality
thereof is also good.
[0020] The above-stated effects of Y incur the
suppression of the Ti inclusions in the steel sheet,
namely, it contributes to suppress the generation of
TiN, TiS, and so on at a hot-rolled sheet annealing
or a cold-rolled sheet finish annealing, and to
suppress the generation of TiC at a strain relief
annealing time.
[0021] Next, limitation reasons of components in the
present invention are described.
[C]
C not only deteriorates the magnetic properties
by forming TiC in the steel sheet but also makes
magnetic aging remarkable by a precipitation of C,
and therefore, an upper limit of a C content is set
at 0.01 mass%. A lower limit of the C content is not
particularly limited because it is more preferable as
it is smaller, and "0" (zero) mass% may be included.
[0022] [Si]
Si is an element decreasing the core loss. It is
impossible to enough decrease the core loss when an
Si content is smaller than 1.0 mass% being a lower
limit. Note that the lower limit of the Si content
is preferably 1.5 mass%, more preferably 2.0 mass%
from a point of view of further decreasing the core
loss. Besides, when the Si content exceeds 3.5 mass%
being an upper limit thereof, processability becomes
remarkably bad, so the upper limit is set at 3.5
mass%. Note that a more preferable value as the
upper limit of the Si content is 3.3 mass% by which
processability at the cold rolling becomes better,
further preferable value is 3.1 mass%, and still
further preferable value is 3.0 mass%.
- 10 -
[0023] [Al]
Al is an element decreasing the core loss similar
to Si. It is impossible to enough decrease the core
loss when an Al content is smaller than 0.1 mass%
being a lower limit. Besides, when the Al content
exceeds 3.0 mass% being an upper limit thereof, the
cost increase is remarkable. Therefore, the lower
limit of the Al content is preferably 0.2 mass%, more
preferably 0.3 mass%, and further preferably 0.4
mass% from a point of view of the core loss. Besides,
the upper limit of the Al content is preferably 2.5
mass%, more preferably 2.0 mass%, and further
preferably 1.8 mass% from a point of view of the cost.
[0024] [Mn]
Mn increases hardness of the steel sheet and
improves a punching property thereof, and therefore,
Mn is added for 0.1 mass% or more. Note that a
reason why an upper limit of an Mn content is set at
2.0 mass% is for an economical reason.
[0025] [P]
P increases strength of a material and improves
the processability, and therefore, P is contained.
Note that the processability at the cold rolling is
lowered when P is excessively contained, and
therefore, a P content is set to be 0.1 mass% or less.
Incidentally, a lower limit of the P content is not
provided because P is inevitably mixed during a
manufacturing process of the steel sheet, but in
general, it is preferable not to set the P content at
- 11 -
less than 0.0001 mass% from a point of view of a
steelmaking cost.
[0026] [Y]
Y acts on Ti in the steel sheet in a soliddissolved
state to suppress the generation of the Ti
inclusions. The effect can be obtained when a Y
content exceeds 0.05 mass%. Besides, the more the
amount of the Y content is, the clearer the effect
becomes, and therefore, it is preferably 0.055 mass%
or more, and more preferably 0.06 mass% or more.
Incidentally, when the Y content becomes excessive, Y
segregates at the grain boundary in the steel sheet,
the grain boundary is embrittled, and deterioration
of a production quality is incurred caused by
generation of scabs and so on. Accordingly, there is
an upper limit in the Y content, and the segregation
of Y at the grain boundary is suppressed when the Y
content is 0.2 mass% or less. The upper limit value
of the Y content is preferably 0.15 mass%, and more
preferably 0.12 mass%.
[0027] [S]
S becomes a sulfide such as TiS and MnS,
deteriorates the crystal grain growth potential, and
deteriorates the core loss. An upper limit of an S
content to prevent the above is 0.0 05 mass%, and a
more preferable upper limit is 0.003 mass%. A lower
limit of the S content is not particularly limited
because the smaller the S content is, the more
preferable it is and "0" (zero) mass% may be included.
- 12 -
[0028] [N]
N becomes a nitride such as TiN and deteriorates
the core loss, and therefore, an allowable upper
limit of an N content is set at 0.005 mass%. Note
that the upper limit of the N content is preferably
0.003 mass%, more preferably 0.0025 mass%, and
further preferably 0.002 mass%. Besides, it is
preferable that an amount of N is smaller as much as
possible from a point of view of suppressing the
generation of the nitride. Accordingly, a lower
limit of the N content is not particularly limited,
but there is a lot of industrial restriction if the N
content is tried to approximate to "0" (zero) mass%
as much as possible, and therefore, it is preferable
to set the lower limit of the N content to be more
than "0" (zero) mass%. Note that an aim of the lower
limit of the N content is 0.001 mass% within a range
capable of performing denitrification in an
industrial manufacturing process. Further, when the
denitrification is ultimately performed, it is more
preferable when the N content is lowered to 0.0005
mass% because the generation of the nitride is
further suppressed.
[0029] [Ti]
Ti generates fine inclusions such as TiN, TiS,
TiC, deteriorates the crystal grain growth potential,
and deteriorates the core loss. The generation of
the Ti inclusions is suppressed by the present
invention, but an allowable upper limit of a Ti
- 13 -
content is set at 0.01 mass%. Besides, the upper
limit is preferably 0.005 mass% from the above-stated
reason. Note that when the Ti content is lower than
0.001 mass%, an amount of Ti precipitate becomes too
small, and a disturbing effect of the crystal grain
growth becomes substantially no problem. On the
other hand, an alloy material whose Ti content is
less than 0.001 mass% is expensive, and therefore, it
leads to the cost increase. Accordingly, it is
allowable up to 0.001 mass% in which Ti is inevitably
mixed to as an impurity as a lower limit in which the
suppression of the generation of the Ti inclusions
according to the present invention is required. Note
that there is a case when Ti is contained in an alloy
material for 0.002 mass% or more when a particularly
cheap alloy material is used, and the present
technology is especially effective in such a case.
[0030] Elements other than the above-described
components may be contained as long as the effect is
not largely disturbed, and they are also within a
range of the present invention. Hereinafter,
selected elements are described. Note that lower
limit values of these contents are all set to be more
than "0" (zero) mass% because it is good as long as
they are contained only for a very small amount.
[0031] [Cu]
Cu improves corrosion resistance, increases
specific resistance, and improves the core loss.
Note that when a Cu content is excessive, scabs and
so on are generated at a surface of a product sheet
to damage a surface quality, and therefore, the Cu
content is preferably 0.5 mass% or less.
[0032] [Cr]
Cr improves the corrosion resistance, increases
the specific resistance, and improves the core loss.
Note that when Cr is excessively added, the cost
increases, and therefore, an upper limit of a Cr
content is preferably set at 20 mass%.
[0033] [Sn] and [Sb]
Sn
the mag
and Sb are segregation elements and improve
net
structure
magnetic p
exhibited
or two
amount
kin
of
proces sabi
therefore,
the tot
[0034]
Ni
for the
Note th
al
[N
ic
on
properties by
a (111) plane
roperties. The
by
ds
Sn
disturbing an aggregate
which deteriorates the
above-stated effect is
using only one kind of these elements,
in combination. Note that when a total
and Sb exceed
lity at the cold
it is preferabl
of
i]
devel
ma
at
increases,
content
[0035]
Ca
steel s
is
[C
i s
hee
Sn and Sb is
s 0.3 mass%, the
rolling deteriorates, and
e that an upper limit of
set at 0.3 mass%.
ops the aggregate structure advantageous
gnetic propertie s to improve the core loss
when Ni is excessively added, the cost
and therefore,
preferably set
a]
a
t,
desulfurizing
and prevents
an upper limit of an Ni
at 1.0 mass%.
element, fixes S in the
or suppresses the
- 15 -
generation of sulfide inclusions such as TiS and MnS.
Incidentally, when a Ca content exceeds 0.01 mass%,
it is not preferable because problems such as erosion
of refractory occurs, and therefore, an upper limit
of the Ca content is preferably set at 0.01 mass%.
[0036] Note that there is a case when, for example,
the following elements are contained as inevitable
impurities, but there is no problem as long as each
of them is within a range described below.
[0037] [Zr]
Even a very small amount of Zr disturbs the
crystal grain growth, and deteriorates the core loss
after the strain relief annealing. When it is
reduced as much as possible, a Zr content generally
becomes 0.01 mass% or less, and when the Zr content
is within this range, there is no adverse effect and
no problem.
[0038] [V]
V forms the nitride or a carbide, and disturbs a
drain wall displacement and the crystal grain growth.
When it is reduced as much as possible, a V content
generally becomes 0.01 mass% or less, and when the V
content is within this range, there is no adverse
effect and no problem.
[0039] [Nb]
Nb forms the nitride or the carbide, and disturbs
the drain wall displacement and the crystal grain
growth. When it is reduced as much as possible, an
Nb content generally becomes 0.01 mass% or less, and
- 16 -
when the Nb content is within this range, there is no
adverse effect and no problem.
[0040] [Mg]
Mg is the desulfurizing element, forms a sulfide
by reacting with S in the steel sheet, and fixes S.
As an Mg content increases, a desulfurizing effect is
enhanced, but when the Mg content exceeds 0.05 mass%,
the crystal grain growth is disturbed by an excessive
Mg sulfide. Generally, the Mg content is 0.05 mass%
or less, and when the Mg content is within this range,
there is no adverse effect and no problem.
[0041] [O]
An oxide is formed by O in the steel sheet.
Incidentally, in the present invention, Al is
contained for 0.1 mass% or more, and it is enough
deoxidized, and therefore, an 0 content in the steel
sheet is 0.005 mass% or less. When the 0 content is
within this range, there is no adverse effect such as
the disturbance of the drain wall displacement and
the crystal grain growth caused by the oxide and no
problem.
[0042] [B]
B is a grain boundary segregation element, and
forms the nitride. A grain boundary migration is
disturbed by the nitride, and the core loss is
deteriorated. When B is reduced as much as possible,
a B content generally becomes 0.005 mass% or less,
and when the B content is within this range, there is
no adverse effect and no problem.
- 17 -
[0043] Next, a manufacturing method of the nonoriented
electrical steel sheet according to the
present invention is described. In a steelmaking
stage, refining is performed according to a
conventional procedure such as a converter and a
secondary refining furnace, and it is produced into a
desired composition range. After that, a cast slab
such as a slab is casted by a continuous casting or
an ingot casting. After this, the obtained cast slab
is hot rolled, and a hot-rolled sheet annealing is
performed for a hot-rolled sheet within a range of
1100°C to 1300°C according to need. Next, it is
finished into a production thickness by one time
cold-rolling or two times or more of cold-rollings
with an intermediate annealing at 850°C to 1000°C
inbetween. Next, a finish annealing is performed
within a range of 800°C to 1100°C, an insulating film
is coated thereon to obtain a product. Besides, the
strain relief annealing is performed within a range
of 700°C to 800°C according to circumstances.
[0044] As described above, according to the present
invention, it is possible to suppress the number
density of the Ti inclusions in the steel sheet into
0.3 x 10 pieces/mm or less, preferably 0.2 x 10 10
pieces/mm3 or less, and more preferably 0.1 x 1010
pieces/mm3 or less without changing the manufacturing
process. Accordingly, it is possible to manufacture
the non-oriented electrical steel sheet whose crystal
grain growth potential is good.
EXAMPLE
[0045] Hereinafter, effects of the present invention
are described based on examples. Note that
conditions and so on in these experiments are just
examples applied to verity operational possibility
and effects of the present invention, and the present
invention is not limited to these examples.
[0046] At first, a steel having components
containing: C: 0.0015 mass%, Si: 2.9 mass%, Mn: 0.5
mass%; P: 0.09 mass%; S: 0.002 mass%; Al: 0.43 mass%,
and N: 0.0022 mass%, and containing various kinds of
elements as represented in Table 1, with the balance
made up of iron and inevitable impurities was
prepared. Then the steel having the above-stated
components was refined by the converter and a vacuum
degassing device, the steel was received by a ladle,
passing through a tundish, a molten steel was
supplied into a mold by an immersion nozzle, it was
continuously casted to obtain a cast slab. Note that
when Y was contained, a metal Y was added in a vacuum
degassing tank. After that, the cast slab was hot
rolled, the hot-rolled sheet annealing was performed
for the obtained hot-rolled sheet at 1150°C, and it
was cold-rolled to be a thickness of 0.35 mm. Then
the finish annealing was performed at 950°C for 30
seconds, the insulating film was coated to be a
product, further the strain relief annealing was
performed at 750°C for two hours.
[0047] The precipitate and the crystal grain
- 19 -
diameter of the product sheet were examined by the
above-stated methods, and the core loss of the
product sheet was examined by an Epstein method
illustrated in JIS-C-2550 by cutting the product
sheet into 25 cm long. Examination results are also
illustrated in Table 1.
[0048] [Table 1]
- 20
TABLE. 1
No.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
COMPONENT VALUE (MASS'S)
[Ti]
0 .0023
0 .0023
0 .0023
0 .0023
0.0023
0.0023
0.0023
0.0023
0.0023
0.0023
0.0023
0.0023
0.0023
0.0023
0.0023
0.0011
[Y]
0.000
0 .005
0 .009
0.025
0.045
0.051
0.056
0.056
0.056
0.056
0.056
0.056
0.056
0.060
0.080
0.080
[Cr]
0
0
0
0
0
0
1.8
0
0
0
0
0
0
0
0
[Cu]
0
0
0
0
0
0
0
0
0. 14
0
0
0
0
0
0
0
[Sn]
0
0
0
0
0
0
0
0
0
0. 08
0
0
0
0
0
0
[Sb]
0
0
0
0
0
0
0
0
0
0
0. 1
0
0
0
0
0
[Ni]
0
0
0
0
0
0
0
0
0
0
0
0.45
0
0
0
0
[Ca]
0
0
0
0
0
0
0
0
0
0
0
0
0.002
0
0
0
RARE-EARTH
ELEMENT
OTHER THAN
m
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
CHARACTERISTICS, MATERIALS, QUALITY OF PRODUCT SHEET
NUMBER OF Ti
INCLUSIONS PER UNIT
VOLUME OF STEEL
(xlO10 pieces/mm3)
&1
4 .0
3.8
3 .7
2.9
1 .4
0.3
0.2
0.2
0.2
0.2
0.2
0.2
0.2
0 .1
0.2
0.1
CRYSTAL
GRAIN
DIAMETER
(Hm)
55
65
70
80
85
100
105
105
110
115
110
110
110
115
125
130
CORE LOSS
W10/800
(W/kg)
61.3
59.5
59.4
58.3
57.7
54.3
53. 1
52. 9
53.3
53.3
53. 1
53.2
52.8
53.2
53.1
52.8
PRESENCE/ABSENCE
OF SURFACE SCABS
ABSENT
ABSENT
ABSENT
ABSENT
ABSENT
ABSENT
ABSENT
ABSENT
ABSENT
ABSENT
ABSENT
ABSENT
ABSENT
ABSENT
ABSENT
ABSENT
REMARKS
COMPARATIVE
EXAMPLE
COMPARATIVE
EXAMPLE
COMPARATIVE
EXAMPLE
COMPARATIVE
EXAMPLE
COMPARATIVE
EXAMPLE
EXAMPLE OF
PRESENT INVENTION
EXAMPLE OF
PRESENT INVENTION
EXAMPLE OF
PRESENT INVENTION
EXAMPLE OF
PRESENT INVENTION
EXAMPLE OF
PRESENT INVENTION
EXAMPLE OF
PRESENT INVENTION
EXAMPLE OF
PRESENT INVENTION
EXAMPLE OF
PRESENT INVENTION
EXAMPLE OF
PRESENT INVENTION
EXAMPLE OF
PRESENT INVENTION
EXAMPLE OF
PRESENT INVENTION
- 21 -
17
18
19
20
21
22
23
24
25
0.0023
0.0095
0.0023
0.0023
0.0023
0.0023
0.0120
0.0011
0.0023
0.115
0.125
0.140'
0.160
0. 190
0.220
0. 080
0.000
0.000
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
La=0.055
Ce=0.080
0.1
0.1
0.1
0. 1
0. 1
0. 1
0. 8
2. 8
2. 1
115
110
120
120
120
115
75
80
70
53.3
53.5
53.3
53.1
53.0
53.4
59. 6
58.6
59.3
ABSENT
ABSENT
ABSENT
ABSENT
ABSENT
PRESENT
ABSENT
ABSENT
ABSENT
EXAMPLE OF
PRESENT INVENTION
EXAMPLE OF
PRESENT INVENTION
EXAMPLE OF
PRESENT INVENTION
EXAMPLE OF
PRESENT INVENTION
EXAMPLE OF
PRESENT INVENTION
COMPARATIVE
EXAMPLE
COMPARATIVE
EXAMPLE
COMPARATIVE
EXAMPLE
COMPARATIVE
EXAMPLE
5&1 TOTAL OF TiN, T i S , TiC
- 22 -
[0049] As illustrated in Table 1, the number of Ti
inclusions (number density) such as TiN, TiS and TiC
in the product sheet was 0.3 x 1010 pieces/mm3 or less
in each of No. 6 to No. 21 being the present
invention's examples. Besides, the crystal grain
diameters of these samples were each 100 \xm or more,
and the crystal grain growth potentials were fine,
and the core loss values were good relative to
comparative examples except No. 22.
[0050] On the other hand, the Y content in each of
No. 1 to No. 5 being the comparative examples was
lower than the lower limit in the range of more than
0.05 mass% to 0.2 mass% or less, besides, the Ti
content in No. 23 being the comparative example was
higher than the upper limit in the range of 0.001
mass% or more and 0.01 mass% or less. Further, a
rare-earth element other than Y was used instead of Y
in No. 24, No. 25 being the comparative examples. In
all of these comparative examples, a number of Ti
inclusions such as TiN, TiS and TiC were generated in
the product sheet, and the crystal grain growth
potential and the core loss value were deteriorated
compared to the present examples. Besides, the Y
content in No. 22 being the comparative example was
higher than the upper limit in the range of more than
0.05 mass% to 0.2 mass% or less, therefore in No. 22
being the comparative example, the segregation of Y
appeared at the grain boundary of the product sheet,
- 23 -
%
scabs were generated at the surface of the product
sheet, and the surface quality was deteriorated.
INDUSTRIAL APPLICABILITY
[0051] As described above, it becomes possible to
obtain fine magnetic properties and to contribute to
energy saving while satisfying needs of customers by
enough suppressing precipitation of TiN, TiS and TiC
contained in the non-oriented electrical steel sheet
- 24 -

,.^1fi.*s%ali
*. Ddl 3
0 ^ iW
CLAIMS
[Claim 1] A non-oriented electrical steel sheet,
containing:
C: 0.01 mass% or less;
Si: 1.0 mass% or more and 3.5. mass% or less;
Al: 0.1 mass% or more and 3.0 mass% or less;
Mn: 0.1 mass% or more and 2.0 mass% or less;
P: 0.1 mass% or less;
S: 0.00 5 mass% or less;
Ti: 0.001 mass% or more and 0.01 mass% or less;
N: 0.00 5 mass% or less; and
Y: more than 0.05 mass% and 0.2 mass% or less,
with a balance being iron and inevitable
impurities.
[Claim 2] The non-oriented electrical steel sheet
according to claim 1, further comprising:
elements of group(s) of one type or two types or
more selected from:
a first group of one type or two types selected
from a group consisting of Cu: 0.5 mass% or less, and
Cr: 2 0 mass% or less;
a second group of one type or two types selected
from a group consisting of Sn and Sb for a total of
0.3 mass% or less;
a third group of Ni: 1.0 mass% or less, and
a fourth group of Ca: 0.01 mass% or less.