The present disclosure relates to a non-oriented
electrical steel sheet and a method of manufacturing the same.
[0002]
Background Art
[0003] An electrical steel sheet may be a product used as a
material for a transformer, a motor, and an electrical device.
Differently from general carbon steel of which workability such
as mechanical properties may be important, an electrical steel
sheet may be a functional product of which electrical properties
may be important. Required electrical properties may include low
iron loss, high magnetic flux density, permeability, and space
factor.
[0004]
[0005] An electrical steel sheet may include an oriented
electrical steel sheet and a non-oriented electrical steel sheet.
An oriented electrical steel sheet may be an electrical steel
sheet having excellent magnetic properties in the rolling
direction by forming Goss texture ({110}<001> texture)
throughout the steel sheet using abnormal grain growth referred
to as secondary recrystallization. A non-oriented electrical
steel sheet may have uniform magnetic properties in all
directions on a rolled sheet.
[0006]
[0007] As a process of producing a non-oriented electrical steel
sheet, a method of hot-rolling, cold-rolling, and final
annealing a slab and forming an insulating coating layer may be
generally used.
[0008]
[0009] As a process of producing an oriented electrical steel
sheet, a method of hot-rolling, preliminary annealing, coldrolling, decarburization annealing, and final annealing a slab
and forming an insulating coating layer may be used.
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[0010]
[0011] Among these, a non-oriented electrical steel sheet may
have uniform magnetic properties in all directions, such that a
non-oriented electrical steel sheet may generally be used as a
material for a motor core, an iron core of generator, an electric
motor, and a small transformer. Representative magnetic
properties of non-oriented electrical steel sheets may be iron
loss and magnetic flux density. The lower iron loss, less iron
loss may be lost during the process of magnetizing the iron core,
which may improve efficiency. The higher the magnetic flux
density, the greater the magnetic strength may be induced with
the same energy, and since less current may be applied to obtain
the same magnetic flux density, copper loss may be reduced,
which may improve energy efficiency.
[0012]
[0013] However, there may be a limitation in improvement of
characteristics of a non-oriented electrical steel sheet based
on general metallurgical techniques, and the degree of iron loss
deterioration of a non-oriented electrical steel sheet not
having undergone stress relief annealing after processing may
not satisfy the strict iron loss-related energy efficiency
regulations and the requirements of industries related to
electric energy production, transmission, conversion, and
utilization.
[0014]
[0015] Recently, to meet demands of these industry demand, it
may be necessary to develop a non-oriented electrical steel
sheet having low iron loss and high magnetic flux density for
manufacturing of a motor having higher efficiency.
[0016]
Detailed description of present disclosure
Technical problems to solve
[0017] An aspect in the present disclosure is to provide a non-
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oriented electrical steel sheet having excellent iron loss and
magnetic flux density properties, and a method of manufacturing
the same.
[0018]
Solution to Problem
[0019] According to an embodiment of the present disclosure, a
non-oriented electrical steel sheet includes, by weight%, Si:
3.0 to 5.0%, Mn: 0.1 to 1.4%, Al: 0.3 to 1.3%, P: 0.001 to 0.01%,
S: 0.003% or less (excluding 0%), C: 0.005% or less (excluding
0%), N: 0.005% or less (excluding 0%), Ti: 0.005% or less
(excluding 0%), one or more of Sn: 0.001 to 0.08% and Sb: 0.001
to 0.08%, and a balance of Fe and inevitable impurities, wherein
an average size of MnS precipitates is 0.5 μm or more, and
wherein a fraction of precipitates having an average size of 3
μm or more is 5 area% or less of entire precipitates.
[0020] According to another embodiment of the present
disclosure, a method of manufacturing a non-oriented electrical
steel sheet includes heating a slab including, by weight%, Si:
3.0 to 5.0%, Mn: 0.1 to 1.4%, Al: 0.3 to 1.3%, P: 0.001 to 0.01%,
S: 0.003% or less (excluding 0%), C: 0.005% or less (excluding
0%), N: 0.005% or less (excluding 0%), Ti: 0.005% or less
(excluding 0%), one or more of Sn: 0.001 to 0.08% and Sb: 0.001
to 0.08%, and a balance of Fe and inevitable impurities;
finishing hot-rolling the heated slab and obtaining a hot-rolled
sheet; primary-cold-rolling the hot-rolled sheet at a cold
reduction ratio of 40 to 79% and obtaining a first cold-rolled
sheet; primary-annealing the first cold-rolled sheet; final
cold-rolling the primary-annealed first cold-rolled sheet and
obtaining a second cold-rolled sheet; and final annealing the
second cold-rolled sheet, wherein, in the primary-cold-rolling,
a finishing cold-rolling temperature is 50 to 160°C, and wherein,
in the final annealing, the steel sheet is held for 50 to 120
seconds at 900 to 1100°C.
[Claim 1]
A non-oriented electrical steel sheet, comprising:
by weight%, Si: 3.0 to 5.0%, Mn: 0.1 to 1.4%, Al: 0.3 to
1.3%, P: 0.001 to 0.01%, S: 0.003% or less (excluding 0%), C:
0.005% or less (excluding 0%), N: 0.005% or less (excluding 0%),
Ti: 0.005% or less (excluding 0%), one or more of Sn: 0.001 to
0.08% and Sb: 0.001 to 0.08%, and a balance of Fe and inevitable
impurities,
wherein an average size of MnS precipitates is 0.5 μm or
more, and
wherein a fraction of precipitates having an average size
of 3 μm or more is 5 area% or less of entire precipitates.
[Claim 2]
The non-oriented electrical steel sheet of claim 1,
wherein Sn and Sb is 0.1% or less in total.
[Claim 3]
The non-oriented electrical steel sheet of claim 1,
wherein the non-oriented electrical steel sheet further includes
one or more of Nb: 0.005% or less and V: 0.005% or less.
[Claim 4]
The non-oriented electrical steel sheet of claim 1,
wherein the non-oriented electrical steel sheet further includes
one or more of Cr: 0.01 to 0.5%, Ni: 0.05% or less, Cu: 0.005
to 0.2% and Zn: 0.01% or less.
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[Claim 5]
The non-oriented electrical steel sheet of claim 1,
wherein the non-oriented electrical steel sheet includes one or
more of Mo: 0.03% or less, B: 0.0050% or less, Ca: 0.005% or
less and Mg: 0.005% or less.
[Claim 6]
The non-oriented electrical steel sheet of claim 1,
wherein the non-oriented electrical steel sheet further includes
0.20% or less (excluding 0%) of one or more of Bi, Pb, Ge and
As individually or in combination.
[Claim 7]
The non-oriented electrical steel sheet of claim 1,
wherein the non-oriented electrical steel sheet has a thickness
of 0.1 to 0.25 mm.
[Claim 8]
The non-oriented electrical steel sheet of claim 1,
wherein the non-oriented electrical steel sheet has a magnetic
flux density (B50) of 1.74-0.028/t+0.00135/t2 (t: thickness of
the steel sheet) Tesla or higher.
[Claim 9]
The non-oriented electrical steel sheet of claim 1,
wherein the non-oriented electrical steel sheet has an iron loss
(W10/400) of 16.18-1.23/t+0.061/t2 (t: thickness of the steel
sheet)W/Kg or lower.
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[Claim 10]
A method of manufacturing a non-oriented electrical steel
sheet, the method comprising:
heating a slab including, by weight%, Si: 3.0 to 5.0%, Mn:
0.1 to 1.4%, Al: 0.3 to 1.3%, P: 0.001 to 0.01%, S: 0.003% or
less (excluding 0%), C: 0.005% or less (excluding 0%), N: 0.005%
or less (excluding 0%), Ti: 0.005% or less (excluding 0%), one
or more of Sn: 0.001 to 0.08% and Sb: 0.001 to 0.08%, and a
balance of Fe and inevitable impurities;
finishing hot-rolling the heated slab and obtaining a hotrolled sheet;
primary-cold-rolling the hot-rolled sheet at a cold
reduction ratio of 40 to 79% and obtaining a first cold-rolled
sheet;
primary-annealing the first cold-rolled sheet;
final cold-rolling the primary-annealed first cold-rolled
sheet and obtaining a second cold-rolled sheet; and
final annealing the second cold-rolled sheet,
wherein, in the primary-cold-rolling, a finishing coldrolling temperature is 50 to 160°C, and
wherein, in the final annealing, the steel sheet is held
for 50 to 120 seconds at 900 to 1100°C.
[Claim 11]
The method of claim 10, wherein Sn and Sb is 0.1% or less
in total.
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[Claim 12]
The method of claim 10, wherein the slab further includes
one or more of Nb: 0.005% or less and V: 0.005% or less.
[Claim 13]
The method of claim 10, wherein the slab further includes
one or more of Cr: 0.01 to 0.5%, Ni: 0.05% or less, Cu: 0.005
to 0.2% and Zn: 0.01% or less.
[Claim 14]
The method of claim 10, wherein the slab further includes
one or more of Mo: 0.03% or less, B: 0.0050% or less, Ca: 0.005%
or less and Mg: 0.005% or less.
[Claim 15]
The method of claim 10, wherein the slab further includes
0.20% or less (excluding 0%) of one or more of Bi, Pb, Ge and
As individually or in combination.
[Claim 16]
The method of claim 10, wherein a temperature of heating
the slab is 1100 to 1180°C.
[Claim 17]
The method of claim 10, wherein a temperature of the
finishing hot-rolling is 870 to 950°C.
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[Claim 18]
The method of claim 10, wherein, in the primary-annealing,
the steel sheet is held for 60 to 360 seconds at 900 to 1140°C.