U.S. patent application number 15/775311 was filed with the patent office on 2018-11-15 for grain-oriented electrical steel sheet and method for manufacturing same.
This patent application is currently assigned to POSCO. The applicant listed for this patent is POSCO. Invention is credited to June Soo PARK, Dae Hyun SONG.
Application Number | 20180327879 15/775311 |
Document ID | / |
Family ID | 57540913 |
Filed Date | 2018-11-15 |
United States Patent
Application |
20180327879 |
Kind Code |
A1 |
SONG; Dae Hyun ; et
al. |
November 15, 2018 |
GRAIN-ORIENTED ELECTRICAL STEEL SHEET AND METHOD FOR MANUFACTURING
SAME
Abstract
The present invention relates to a grain-oriented electrical
steel sheet and a method for manufacturing the same. The
grain-oriented electrical steel sheet contains 2.0 wt % or more to
5.0 wt % or less of Si, 0.005 wt % or more to 0.04 wt % or less of
acid-soluble Al, 0.01 wt % or more to 0.2 wt % or less of Mn, 0.01
wt % or less (excluding 0 wt %) of N, 0.01 wt % or less (excluding
0 wt %) of S, 0.01 wt % or more to 0.05 wt % or less of Sb, 0.02 wt
% or more to 0.08 wt % or less of C, 0.0005 wt % or more to 0.045
wt % or less of P, 0.03 wt % or more to less than 0.08 wt % of Sn,
and 0.01 wt % or more to 0.2 wt % or less of Cr, and contains
balance Fe and other inevitable impurities.
Inventors: |
SONG; Dae Hyun; (Pohang-si,
Gyeongsangbuk-do, KR) ; PARK; June Soo; (Pohang-si,
Gyeongsangbuk-do, KR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
POSCO |
Pohang-si, Gyeongsangbuk-do |
|
KR |
|
|
Assignee: |
POSCO
Pohang-si, Gyeongsangbuk-do
KR
|
Family ID: |
57540913 |
Appl. No.: |
15/775311 |
Filed: |
November 9, 2016 |
PCT Filed: |
November 9, 2016 |
PCT NO: |
PCT/KR2016/012851 |
371 Date: |
May 10, 2018 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C22C 38/34 20130101;
C21D 8/12 20130101; C22C 38/04 20130101; C21D 8/1233 20130101; C22C
38/60 20130101; C23C 8/02 20130101; C22C 38/06 20130101; C22C 38/00
20130101; C21D 8/1222 20130101; Y02P 10/20 20151101; C22C 38/008
20130101; C22C 38/02 20130101; C21D 8/1272 20130101; C21D 1/74
20130101; C23C 2/00 20130101; C21D 6/008 20130101; C21D 8/1283
20130101; C21D 8/1255 20130101; C23C 8/26 20130101; C23C 8/80
20130101; C22C 38/001 20130101 |
International
Class: |
C21D 8/12 20060101
C21D008/12; C22C 38/02 20060101 C22C038/02; C22C 38/34 20060101
C22C038/34 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 10, 2015 |
KR |
10-2015-0157540 |
Claims
1. A grain-oriented electrical steel sheet containing 2.0 wt % or
more to 5.0 wt % or less of Si, 0.005 wt % or more to 0.04 wt % or
less of acid-soluble Al, 0.01 wt % or more to 0.2 wt % or less of
Mn, 0.01 wt % or less (excluding 0 wt %) of N, 0.01 wt % or less
(excluding 0 wt %) of S, 0.01 wt % or more to 0.05 wt % or less of
Sb, 0.02 wt % or more to 0.08 wt % or less of C, 0.0005 wt % or
more to 0.045 wt % or less of P, 0.03 wt % or more to less than
0.08 wt % of Sn, and 0.01 wt % or more to 0.2 wt % or less of Cr,
and containing balance Fe and other inevitable impurities.
2. The grain-oriented electrical steel sheet of claim 1, wherein:
the grain-oriented electrical steel sheet satisfies the following
Equation 1 calculated by contents (wt %) of the respective
components: -0.32Mn+0.012Si+0.016.ltoreq.C.ltoreq.-0.014Mn+0.02Si.
[Equation 1]
3. The grain-oriented electrical steel sheet of claim 1, wherein:
the grain-oriented electrical steel sheet satisfies the following
Equation 2 calculated by contents (wt %) of the respective
components: Sn+Sb.ltoreq.5Cr. [Equation 2]
4. The grain-oriented electrical steel sheet of claim 1, wherein:
the grain-oriented electrical steel sheet satisfies the following
Equation 1 and the following Equation 2 calculated by contents (wt
%) of the respective components:
-0.32Mn+0.012Si+0.016.ltoreq.C.ltoreq.-0.014Mn+0.02Si, and [ 1]
Sn+Sb.ltoreq.5Cr. [ 2]
5. The grain-oriented electrical steel sheet of claim 4, wherein: a
fracture of an austenite phase in the grain-oriented electrical
steel is 20 to 30%.
6. The grain-oriented electrical steel sheet of claim 5, wherein:
an area of crystal grains of which a ratio between the longest
diameters and the shortest diameters is 1.0 or more among crystal
grains of which lengths of the shortest diameters are 3 mm or more
is 5% or more of an area of all the crystal grains.
7. A method for manufacturing a grain-oriented electrical steel
sheet, comprising: reheating a steel slab containing 2.0 wt % or
more to 5.0 wt % or less of Si, 0.005 wt % or more to 0.04 wt % or
less of acid-soluble Al, 0.01 wt % or more to 0.2 wt % or less of
Mn, 0.01 wt % or less (excluding 0 wt %) of N, 0.01 wt % or less
(excluding 0 wt %) of S, 0.01 wt % or more to 0.05 wt % or less of
Sb, 0.02 wt % or more to 0.08 wt % or less of C, 0.0005 wt % or
more to 0.045 wt % or less of P, 0.03 wt % or more to less than
0.08 wt % of Sn, and 0.01 wt % or more to 0.2 wt % or less of Cr,
and including balance Fe and other inevitable impurities;
manufacturing a steel sheet by performing hot rolling, hot-rolled
sheet annealing, and cold rolling on the reheated steel slab;
performing decarbonization annealing and nitriding annealing on the
cold-rolled steel sheet; and finally annealing the decarbonization
annealed and nitriding annealed steel sheet.
8. The method for manufacturing a grain-oriented electrical steel
sheet of claim 7, wherein: the steel slab satisfies the following
Equation 1 calculated by contents (wt %) of the respective
components: -0.32Mn+0.012Si+0.016.ltoreq.C.ltoreq.-0.014Mn+0.02Si.
[Equation 1]
9. The method for manufacturing a grain-oriented electrical steel
sheet of claim 7, wherein: the steel slab satisfies the following
Equation 2 calculated by contents (wt %) of the respective
components: Sn+Sb.ltoreq.5Cr. [Equation 2]
10. The method for manufacturing a grain-oriented electrical steel
sheet of claim 7, wherein: the steel slab satisfies the following
Equation 1 and the following Equation 2 calculated by contents (wt
%) of the respective components:
-0.32Mn+0.012Si+0.016.ltoreq.C.ltoreq.-0.014Mn+0.02Si, and
[Equation 1] Sn+Sb.ltoreq.5Cr. [Equation 2]
11. The method for manufacturing a grain-oriented electrical steel
sheet of claim 10, wherein: in the reheating of the steel slab, a
temperature is 1000 to 1250.degree. C.
12. The method for manufacturing a grain-oriented electrical steel
sheet of claim 11, wherein: in the manufacturing of the steel sheet
by performing the hot rolling, the hot-rolled sheet annealing, and
the cold rolling on the reheated steel slab, a hot-rolled sheet
annealing temperature is 900 to 1200.degree. C.
13. The method for manufacturing a grain-oriented electrical steel
sheet of claim 12, wherein: in the manufacturing of the steel sheet
by performing the hot rolling, the hot-rolled sheet annealing, and
the cold rolling on the reheated steel slab, a cold rolling
thickness is 0.10 mm or more to 0.50 mm or less.
14. The method for manufacturing a grain-oriented electrical steel
sheet of claim 13, wherein: in the manufacturing of the steel sheet
by performing the hot rolling, the hot-rolled sheet annealing, and
the cold rolling on the reheated steel slab, the cold rolling is
performed as once cold rolling of which a cold rolling ratio is 87%
or more.
15. The method for manufacturing a grain-oriented electrical steel
sheet of claim 14, wherein: in the performing of the
decarbonization annealing and the nitriding annealing on the
cold-rolled steel sheet, the decarbonization annealing and the
nitriding annealing are simultaneously performed, the nitriding
annealing is independently performed after the decarbonization
annealing, or the decarbonization annealing is independently
performed after the nitriding annealing.
16. The method for manufacturing a grain-oriented electrical steel
sheet of claim 15, wherein: in the performing of the
decarbonization annealing and the nitriding annealing on the
cold-rolled steel sheet, the decarbonization annealing and the
nitriding annealing are simultaneously performed, and an annealing
temperature is 800 to 950.degree. C.
17. The method for manufacturing a grain-oriented electrical steel
sheet of claim 16, further comprising: before the final annealing
of the decarbonization annealed and nitriding annealed steel sheet,
applying an annealing separating agent to the decarbonization
annealed and nitriding annealed steel sheet.
18. The method for manufacturing a grain-oriented electrical steel
sheet of claim 17, wherein: in the final annealing of the
decarbonization annealed and nitriding annealed steel sheet, a
final annealing temperature is 800 to 1250.degree. C.
19. The method for manufacturing a grain-oriented electrical steel
sheet of claim 18, wherein: the final annealing of the
decarbonization annealed and nitriding annealed steel sheet is
performed under an atmosphere including one or more of nitrogen and
hydrogen, and is performed under a 100% hydrogen atmosphere after a
temperature arrives at the final annealing temperature.
Description
TECHNICAL FIELD
[0001] The present invention relates to a grain-oriented electrical
steel sheet and a method for manufacturing the same.
BACKGROUND ART
[0002] A grain-oriented electrical steel sheet is a soft magnetic
material having excellent magnetic characteristics in one direction
or a rolling direction since a texture of a bloom with respect to
the rolling direction is a Goss texture, which is {110}<001>.
In order to reveal such a texture, complicated processes such as
component control in steelmaking, slab reheating and hot rolling
process factor control in hot rolling, hot-rolled sheet annealing
heat treatment, primary recrystallization annealing, and secondary
recrystallization annealing, and the like, are required, and need
to be very precisely and strictly managed. Meanwhile, it is also
very important to control inhibitors, which are one of factors
revealing the Goss texture, that is, crystal grain growth
inhibitors inhibiting indiscriminate growth of primary
recrystallized grains and allowing only the Goss texture to be
grown at the time of generation of the secondary recrystallization.
In order to obtain the Goss texture in final annealing, growth of
all the primary recrystallized grains needs to be inhibited until
just before the secondary recrystallization is generated, and in
order to obtain sufficient inhibition ability for the inhibition of
the growth, an amount of inhibitors needs to be sufficiently large
and a distribution of the inhibitors needs to be uniform.
Meanwhile, in order to allow the secondary recrystallization to be
generated during a high-temperature final annealing process, the
inhibitors needs to have excellent thermal stability so as not to
be easily decomposed. The secondary recrystallization is a
phenomenon occurring since the inhibitors inhibiting the growth of
the primary recrystallized grains are decomposed in an appropriate
temperature section and lose the inhibition ability, at the time of
the final annealing. In this case, specific crystal grains such as
Goss crystal grains are rapidly grown in a relatively short
time.
[0003] Generally, quality of a grain-oriented electrical steel
sheet may be evaluated by a magnetic flux density and core loss,
which are typical magnetic characteristics, and the higher the
precision of the Goss texture, the more excellent the magnetic
characteristics. In addition, a grain-oriented electrical steel
sheet having excellent quality may manufacture an electric power
device having high efficiency due to material characteristics, such
that miniaturization and efficiency improvement of the electric
power device may be accomplished.
[0004] The related arts overcome a limitation of cold rolling
through warm rolling after increasing a content of silicon or
decrease the core loss by increasing a specific resistance through
siliconizing, in order to improve the magnetic characteristics of
the grain-oriented electrical steel sheet. However, in this case,
an additional process is required, and a manufacturing cost is
increased. In addition, schematic configurations of technologies of
manufacturing a grain-oriented electrical steel sheet by adding
alloy elements such as Ti, B, Se, Sb, Sn, Cr, and the like, in
order to improve crystal grain growth inhibition ability are
described. However, ranges of the alloy elements are generally
described excessively widely, a description for an effect of each
of the alloy elements is small, and a case in which the
grain-oriented electrical steel sheet includes two or more kinds or
alloy elements rather an effect of a single alloy element are
mainly described. That is, according to the known technologies up
to now, it is described only that the magnetic characteristics of
the grain-oriented electrical steel sheet may be improved by adding
Ti, B, Se, Sb, Sn, Cr, and the like, and direct effects,
appropriate contents, and identification of a synergy effect by an
interaction between two or more kinds or alloy elements when the
two or more alloying elements are added are hardly described. That
is, a detailed method capable of appropriately exerting effects of
the alloy elements described above is not provided, and even though
the detailed method capable of appropriately exerting effects of
the alloy elements described above is provided, causes and
relationship identification are not enough.
DISCLOSURE
Technical Problem
[0005] The present invention has been made in an effort to provide
a grain-oriented electrical steel sheet and a method for
manufacturing the same having advantages of having small core loss
and an excellent magnetic flux density.
Technical Solution
[0006] An exemplary embodiment of the present invention provides a
grain-oriented electrical steel sheet including 2.0 wt % or more to
5.0 wt % or less of Si, 0.005 wt % or more to 0.04 wt % or less of
acid-soluble Al, 0.01 wt % or more to 0.2 wt % or less of Mn, 0.01
wt % or less (excluding 0 wt %) of N, 0.01 wt % or less (excluding
0 wt %) of S, 0.01 wt % or more to 0.05 wt % or less of Sb, 0.02 wt
% or more to 0.08 wt % or less of C, 0.0005 wt % or more to 0.045
wt % or less of P, 0.03 wt % or more to less than 0.08 wt % of Sn,
and 0.01 wt % or more to 0.2 wt % or less of Cr, and including
balance Fe and other inevitable impurities.
[0007] The grain-oriented electrical steel sheet may satisfy the
following Equation 1 calculated by contents (wt %) of the
respective components:
-0.32Mn+0.012Si+0.016.ltoreq.C.ltoreq.-0.014Mn+0.02Si. [Equation
1]
[0008] The grain-oriented electrical steel sheet may satisfy the
following Equation 2 calculated by contents (wt %) of the
respective components:
Sn+Sb.ltoreq.5Cr. [Equation 2]
[0009] The grain-oriented electrical steel sheet may satisfy the
following Equation 1 and the following Equation 2 calculated by
contents (wt %) of the respective components:
-0.32Mn+0.012Si+0.016.ltoreq.C.ltoreq.-0.014Mn+0.02Si, and
[Equation 1]
Sn+Sb.ltoreq.5Cr. [Equation 2]
[0010] A fracture of an austenite phase in the grain-oriented
electrical steel may be 20 to 30%.
[0011] An area of crystal grains of which a ratio between the
longest diameters and the shortest diameters is 1.0 or more among
crystal grains of which lengths of the shortest diameters are 3 mm
or more may be 5% or more of an area of all the crystal grains.
[0012] Another exemplary embodiment of the present invention
provides a method for manufacturing a grain-oriented electrical
steel sheet including reheating a steel slab containing 2.0 wt % or
more to 5.0 wt % or less of Si, 0.005 wt % or more to 0.04 wt % or
less of acid-soluble Al, 0.01 wt % or more to 0.2 wt % or less of
Mn, 0.01 wt % or less (excluding 0 wt %) of N, 0.01 wt % or less
(excluding 0 wt %) of S, 0.01 wt % or more to 0.05 wt % or less of
Sb, 0.02 wt % or more to 0.08 wt % or less of C, 0.0005 wt % or
more to 0.045 wt % or less of P, 0.03 wt % or more to less than
0.08 wt % of Sn, and 0.01 wt % or more to 0.2 wt % or less of Cr,
and including balance Fe and other inevitable impurities;
manufacturing a steel sheet by performing hot rolling, hot-rolled
sheet annealing, and cold rolling on the reheated steel slab;
performing decarbonization annealing and nitriding annealing on the
cold-rolled steel sheet; and finally annealing the decarbonization
annealed and nitriding annealed steel sheet.
[0013] The steel slab may satisfy the following Equation 1
calculated by contents (wt %) of the respective components:
-0.32Mn+0.012Si+0.016.ltoreq.C.ltoreq.-0.014Mn+0.02Si. [Equation
1]
[0014] The steel slab may satisfy the following Equation 2
calculated by contents (wt %) of the respective components:
Sn+Sb.ltoreq.5Cr. [Equation 2]
[0015] The steel slab may satisfy the following Equation 1 and the
following Equation 2 calculated by contents (wt %) of the
respective components:
-0.32Mn+0.012Si+0.016.ltoreq.C.ltoreq.-0.014Mn+0.02Si, and
[Equation 1]
Sn+Sb.ltoreq.5Cr. [Equation 2]
[0016] In the reheating of the steel slab, a temperature may be
1000 to 1250.degree. C.
[0017] In the manufacturing of the steel sheet by performing the
hot rolling, the hot-rolled sheet annealing, and the cold rolling
on the reheated steel slab, a hot-rolled sheet annealing
temperature may be 900 to 1200.degree. C.
[0018] In the manufacturing of the steel sheet by performing the
hot rolling, the hot-rolled sheet annealing, and the cold rolling
on the reheated steel slab, a cold rolling thickness may be 0.10 mm
or more to 0.50 mm or less.
[0019] In the manufacturing of the steel sheet by performing the
hot rolling, the hot-rolled sheet annealing, and the cold rolling
on the reheated steel slab, the cold rolling may be performed as
once cold rolling of which a cold rolling ratio is 87% or more.
[0020] In the performing of the decarbonization annealing and the
nitriding annealing on the cold-rolled steel sheet, the
decarbonization annealing and the nitriding annealing may be
simultaneously performed, the nitriding annealing may be
independently performed after the decarbonization annealing, or the
decarbonization annealing may be independently performed after the
nitriding annealing.
[0021] In the performing of the decarbonization annealing and the
nitriding annealing on the cold-rolled steel sheet, the
decarbonization annealing and the nitriding annealing may be
simultaneously performed, and an annealing temperature may be 800
to 950.degree. C.
[0022] The method for manufacturing a grain-oriented electrical
steel sheet may further include applying an annealing separating
agent to the decarbonization annealed and nitriding annealed steel
sheet.
[0023] In the final annealing of the decarbonization annealed and
nitriding annealed steel sheet, a final annealing temperature may
be 800 to 1250.degree. C.
[0024] The final annealing of the decarbonization annealed and
nitriding annealed steel sheet may be performed under an atmosphere
including one or more of nitrogen and hydrogen, and may be
performed under a 100% hydrogen atmosphere after a temperature
arrives at the final annealing temperature.
Advantageous Effects
[0025] A grain-oriented electrical steel sheet having small core
loss and an excellent magnetic flux density, and a method for
manufacturing the same are provided.
DESCRIPTION OF THE DRAWINGS
[0026] Hereinafter, an exemplary embodiment of the present
invention is described in detail. However, it is to be understood
that this exemplary embodiment is provided as an example, and the
present invention is not limited by this exemplary embodiment, but
is defined by only the scope of claims to be described below.
[0027] In the present specification, "%" means wt % unless defined
otherwise.
[0028] An exemplary embodiment of the present invention provides a
grain-oriented electrical steel sheet containing 2.0 wt % or more
to 5.0 wt % or less of Si, 0.005 wt % or more to 0.04 wt % or less
of acid-soluble Al, 0.01 wt % or more to 0.2 wt % or less of Mn,
0.01 wt % or less (excluding 0 wt %) of N, 0.01 wt % or less
(excluding 0 wt %) of S, 0.01 wt % or more to 0.05 wt % or less of
Sb, 0.02 wt % or more to 0.08 wt % or less of C, 0.0005 wt % or
more to 0.045 wt % or less of P, 0.03 wt % or more to less than
0.08 wt % of Sn, and 0.01 wt % or more to 0.2 wt % or less of Cr,
and containing balance Fe and other inevitable impurities.
[0029] In detail, the grain-oriented electrical steel sheet may
satisfy the following Equation 1 calculated by contents (wt %) of
the respective components:
-0.32Mn+0.012Si+0.016.ltoreq.C.ltoreq.-0.014Mn+0.02Si. [Equation
1]
[0030] In detail, the grain-oriented electrical steel sheet may
satisfy the following Equation 2 calculated by contents (wt %) of
the respective components;
Sn+Sb.ltoreq.5Cr. [Equation 2]
[0031] In more detail, the grain-oriented electrical steel sheet
may satisfy the following Equation 1 and the following Equation 2
calculated by contents (wt %) of the respective components:
-0.32Mn+0.012Si+0.016.ltoreq.C.ltoreq.-0.014Mn+0.02Si, and
[Equation 1]
Sn+Sb.ltoreq.5Cr. [Equation 2]
[0032] Contents (wt %) of Mn, Si, and C are controlled to satisfy
the above Equation 1. This is to allowing a phase transformation
fracture of an austenite phase that cannot but be inevitably
generated in temperature ranges of steel slab reheating, hot
rolling, and the subsequent hot-rolled sheet annealing at the time
of manufacturing the grain-oriented electrical steel sheet to be
maintained in 20 to 30%. In the case in which an amount of
austenite phase is excessively small, a hot-rolled sheet
microstructure may remain in a final product after high-temperature
annealing to deteriorate the magnetic characteristics. In the case
in which an amount of austenite phase is excessively large,
.alpha.+.gamma. phase transformation may be excessively activated
during primary recrystallization annealing (decarbonization
annealing), resulting in damage to a Goss texture.
[0033] The contents (wt %) of Sn, Sb, and Cr are controlled to
satisfy the above Equation 2. This is to allow an oxide layer of a
decarbonized annealed sheet that becomes a base of a base coating
to be appropriately formed.
[0034] The grain-oriented electrical steel sheet may be a
grain-oriented electrical steel sheet in which an area of crystal
grains of which a ratio between the longest diameters and the
shortest diameters is 1.0 or more among crystal grains of which
lengths of the shortest diameters are 3 mm or more is 5% or more of
an area of all the crystal grains. In a case of a grain-oriented
electrical steel sheet having a large number of crystal grains
grown in a rolling direction, magnetic characteristics in the
rolling direction demanded by the grain-oriented electrical steel
sheet itself may be more excellent.
[0035] Hereinafter, the reason why contents of the respective
components are limited is described in detail. % means wt %.
[0036] Si: 2.0% or more to 5.0% or less
[0037] Si, which is a basic composition of the grain-oriented
electrical steel sheet, serves to increase a specific resistance of
a material to decrease core loss. In the case in which a content of
Si is less than 2.0%, the specific resistance is decreased, such
eddy current loss is increased, and core loss characteristics are
thus deteriorated. In addition, at the time of decarbonization
nitriding annealing, phase transformation between ferrite and
austenite becomes active, such that a primary recrystallization
texture is severely damaged. In addition, at the time of
high-temperature annealing, the phase transformation between
ferrite and austenite is generated, such that secondary
recrystallization becomes unstable, and a {110} Goss texture is
severely damaged.
[0038] In the case in which the content of Si exceeds 5.0%, at the
time of the decarbonization nitriding annealing, SiO.sub.2 and
Fe.sub.2SiO.sub.4 oxide layers are excessively and densely formed
to delay decarbonization behavior. Therefore, phase transformation
between ferrite and austenite is continuously generated during the
decarbonization nitriding annealing, such that a primary
recrystallization texture is severely damaged. Nitriding behavior
is delayed due to a decarbonization behavior delay effect depending
on the formation of the dense oxide layer described above, such
that nitrides such as (Al,Si,Mn)N, AlN, and the like, are not
sufficiently formed. Therefore, sufficient crystal grain inhibition
ability required for the secondary recrystallization at the time of
the high-temperature annealing may not be secured. In addition,
when the content of Si exceeds 5.0%, a brittleness and a roughness,
which are mechanical characteristics of the grain-oriented
electrical steel sheet, are increased and decreased, respectively,
resulting an increase in a sheet fracture occurrence rate in a
rolling process. Therefore, weldability between sheets is
deteriorated, such that easy workability may not be secured.
[0039] Resultantly, when the content of Si is not controlled in the
predetermined range described above, formation of the secondary
recrystallization becomes unstable. Therefore, magnetic
characteristics are severely damaged, and workability is also
deteriorated. Therefore, it is preferable that the content of Si is
limited to 2.0% or more to 5.0% or less.
[0040] acid-soluble Al: 0.005% or more to 0.04% or less
[0041] Al forms AlN finely precipitated at the time of hot rolling
and hot-rolled sheet annealing or is combined with Al, Si, and Mn
in which nitrogen ions introduced by an ammonia gas exist in a
solid-dissolved state within steel in an annealing process after
cold rolling, thereby forming (Al, Si, Mn) N and AlN type nitrides.
The materials described above serve as strong crystal grain growth
inhibitors.
[0042] In the case in which a content of Al is less than 0.005%,
the number and a volume of materials described above are
significantly low, such that a sufficient effect of the materials
described above as the inhibitors may not be expected.
[0043] In the case in which the content of Al exceeds 0.04%, coarse
nitrides are formed, such that crystal grain growth inhibition
ability is decreased. Therefore, the content of Al is limited to
0.005% or more to 0.04% or less.
[0044] Mn: 0.01% or more to 0.2% or less
[0045] Mn increases the specific resistance to decrease the eddy
current loss, resulting in a decrease in entire core loss, similar
to Si. In addition, Mn forms an Mn-based sulfide by reacting to S
in a fired steel state, or forms a precipitate of (Al, Si, Mn) N by
reacting to nitrogen introduced by the nitriding together with Si.
Therefore, Mn is an important element in inhibiting growth of
primary recrystallized grains and generating the secondary
recrystallization.
[0046] In the case in which a content of Mn is less than 0.01%, the
number and a volume of materials described above are significantly
low, such that a sufficient effect of the materials described above
as the inhibitors may not be expected.
[0047] In the case in which the content of Mn exceeds 0.2%, large
amounts of (Fe, Mn) and Mn oxides are formed in addition to
Fe.sub.2SiO.sub.4 on a surface of the steel sheet to hinder the
base coating from being formed during the high-temperature
annealing, resulting in deterioration of surface quality. In
addition, since phase transformation between ferrite and austenite
is caused in a high-temperature annealing process, the texture is
severely damaged, such that the magnetic characteristics are
significantly deteriorated. Therefore, the content of Mn is limited
to 0.01% or more to 0.2% or less.
[0048] N: 0.01% or less (excluding 0%)
[0049] N is an important element forming AlN and BN by reacting to
Al and B, and it is preferable to add 0.01% or less of N in a
steelmaking step.
[0050] When a content of added N exceeds 0.01%, a surface defect
such as a blister is caused by nitrogen diffusion in a process
after hot rolling. In addition, since an excessive large amount of
nitrides are formed in a slab state, rolling becomes difficult,
such that the next process may be complicated and a manufacturing
cost may be increased. Meanwhile, N additionally required in order
to form nitrides such as (Al,Si,Mn)N, AlN, (B,Si,Mn)N, (Al,B)N, BN,
and the like, is reinforced by performing nitriding in steel using
an ammonia gas in the annealing process after the cold rolling.
[0051] C: 0.02% or more to 0.08% or less
[0052] C is an element contributing to grain refinement and
improvement of an elongation percentage by generating phase
transformation between ferrite and austenite. C is an essential
element for improving a rolling property of the grain-oriented
electrical steel sheet having a poor rolling property due to a high
brittleness. However, since C is an element deteriorating the
magnetic characteristics by precipitating carbides formed due to a
magnetic aging effect in a product sheet in the case in which it
remains in a final product, a content of C needs to be
appropriately controlled.
[0053] When a content of C is less than 0.02% in the range of the
content of Si described above, the phase transformation between the
ferrite and the austenite is not sufficiently generated, which
causes non-uniformity of a slab and a hot rolled microstructure.
Therefore, a cold rolling property is damaged.
[0054] When the content of C exceeds 0.08% in the range of the
content of Si described above, sufficient decarbonization may not
be obtained in a decarbonization annealing process unless a
separate process or equipment is added. Due to a phase
transformation phenomenon caused by the reason described above, a
secondary recrystallization texture is severely damaged. Further, a
deterioration phenomenon of the magnetic characteristics by
magnetic aging is caused at the time of applying a final product to
an electric power device.
[0055] Therefore, the content of C is limited to 0.02% or more to
0.08% or less.
[0056] S: 0.01% or less (excluding 0%)
[0057] When a content of S exceeds 0.01%, precipitates of MnS are
formed in the slab to inhibit crystal grain growth. In addition, S
is segregated at a central portion of the slab at the time of
casting, such that it is difficult to control a microstructure in
the subsequent process. In addition, since MnS is not used as a
crystal grain growth inhibitor in the present invention, it is not
preferable that S is added and precipitated by an inevitable
content or more. Therefore, it is preferable that the content of S
is 0.01% or less.
[0058] P: 0.0005% or more to 0.045% or less
[0059] P is segregated in grain boundaries to hinder movement of
the grain boundaries, and at the same time, may play an auxiliary
role of inhibiting crystal grain growth. Therefore, there is an
effect of improving a {110}<001> texture in terms of a
microstructure. When a content of P is less than 0.0005%, there is
no addition effect of P, and when the content of P exceeds 0.045%,
a brittleness is increased, such that a rolling property is
significantly deteriorated. Therefore, it is preferable that the
content of P is limited to 0.0005% or more to 0.045% or less.
[0060] Sb: 0.01% or more to 0.05% or less
[0061] Sb is segregated in the grain boundaries to hinder crystal
grain growth, similar to P, and stabilizes the secondary
recrystallization. However, Si has a low melting point, and may
thus be easily diffused to the surface during the primary
recrystallization annealing to hinder decarbonization, formation of
an oxide layer, and nitriding. Therefore, when Sb is added by a
predetermined level or more, it hinders the decarbonization and
inhibits the formation of the oxide layer that becomes the base of
the base coating, and thus, there is an upper limit in a content of
added Sb.
[0062] As a result of continuous research by the present inventors,
it has been found that at least 0.01% of Sb needs to be added in
order for a crystal grain growth inhibition effect to appear. In
addition, when a content of Sb exceeds 0.05%, the inhibition effect
and diffusion of Sb to the surface becomes severs, such that stable
secondary recrystallization is not obtained. In addition, it was
found that surface quality is deteriorated. Therefore, it is
preferable that the content of Sb has a range of 0.01% or more to
0.05% or less.
[0063] Sn: 0.03% or more to less than 0.08%
[0064] Sn, which is a grain boundary segregated element, similar to
P, is an element hindering movement of grain boundaries, and is
thus known as a crystal grain growth inhibitor. In a predetermined
range of the content of Si of the present invention, crystal grain
growth inhibition ability for smooth secondary recrystallization
behavior at the time of the high-temperature annealing is
insufficient. Therefore, Sn segregated in the grain boundaries to
hinder the movement of the grain boundaries is necessarily
required.
[0065] The present inventors have found that in the case in which a
content of Sn is less than 0.03%, an improvement effect of the
magnetic characteristics appears as compared with a case in which
Si does not exist at all, but is slight, through continuous
research. In addition, they have found that in the case in which
the content of Sn is 0.08% or more, when a temperature increase
speed is not adjusted or maintained for a predetermined time in a
primary recrystallization annealing section, crystal grain growth
inhibition ability is excessively strong, such that stable
secondary recrystallization may not be obtained. Therefore, it is
preferable that the content of Sn is 0.03% or more and is less than
0.08.
[0066] Cr: 0.01% or more to 0.2% or less
[0067] Cr promotes formation of a hard phase in a hot-rolled
annealed sheet to promote formation of {110}<001> of the Goss
texture at the time of the cold rolling. In addition, Cr promotes
decarbonization in a decarbonization annealing process to decrease
an austenite phase transformation maintaining time, resulting in
prevention of damage to the texture. In addition, Cr promotes
formation of an oxide layer of a surface formed in the
decarbonization annealing process to complement a disadvantage that
formation of the oxide layer is hindered due to Sn and Sb.
[0068] The present inventors have found that in the case in which a
content of Cr is less than 0.01%, the effect described above
appears as compared with a case in which Cr does not exist at all,
but is slight, through continuous research. In addition, they have
found that in the case in which the content of Cr exceeds 0.2%, the
oxide layer is more densely formed in the decarbonization annealing
process. Therefore, the formation of the oxide layer is
deteriorated, and the decarbonization and the nitriding are
hindered. In addition, since C is an expensive alloy element, it is
preferable that an upper limit value of the content of Cr is set to
0.2% or less.
[0069] The grain-oriented electrical steel sheet according to the
present invention described above may be manufactured by a method
for manufacturing a grain-oriented electrical steel sheet
well-known in the technical field to which the present invention
pertains, but it is more preferable that the grain-oriented
electrical steel sheet is manufactured by a method for
manufacturing a grain-oriented electrical steel sheet to be
described below. Hereinafter, a more preferably method for
manufacturing a grain-oriented electrical steel sheet is described.
Conditions which are not specifically described below are
considered to be in accordance with general conditions.
[0070] An another exemplary embodiment of the present invention
provides a method for manufacturing a grain-oriented electrical
steel sheet including reheating a steel slab containing 2.0 wt % or
more to 5.0 wt % or less of Si, 0.005 wt % or more to 0.04 wt % or
less of acid-soluble Al, 0.01 wt % or more to 0.2 wt % or less of
Mn, 0.01 wt % or less (excluding 0 wt %) of N, 0.01 wt % or less
(excluding 0 wt %) of S, 0.01 wt % or more to 0.05 wt % or less of
Sb, 0.02 wt % or more to 0.08 wt % or less of C, 0.0005 wt % or
more to 0.045 wt % or less of P, 0.03 wt % or more to less than
0.08 wt % of Sn, and 0.01 wt % or more to 0.2 wt % or less of Cr,
and including balance Fe and other inevitable impurities;
manufacturing a steel sheet by performing hot rolling, hot-rolled
sheet annealing, and cold rolling on the reheated steel slab;
performing decarbonization annealing and nitriding annealing on the
cold-rolled steel sheet; and finally annealing the decarbonization
annealed and nitriding annealed steel sheet.
[0071] In detail, the steel slab may satisfy the following Equation
1 calculated by contents (wt %) of the respective components:
-0.32Mn+0.012Si+0.016.ltoreq.C.ltoreq.-0.014Mn+0.02Si. [Equation
1]
[0072] In detail, the steel slab may satisfy the following Equation
2 calculated by contents (wt %) of the respective components:
Sn+Sb.ltoreq.5Cr. [Equation 2]
[0073] In more detail, the steel slab may satisfy the following
Equation 1 and the following Equation 2 calculated by contents (wt
%) of the respective components:
-0.32Mn+0.012Si+0.016.ltoreq.C.ltoreq.-0.014Mn+0.02Si, and
[Equation 1]
Sn+Sb.ltoreq.5Cr. [Equation 2]
[0074] Hereinafter, the method for manufacturing a grain-oriented
electrical steel sheet is described in detail.
[0075] It is preferable to reheat the steel slab at a temperature
range in which precipitates of Al-based nitrides or Mn-based
sulfides are incompletely solution-treated or completely
solution-treated depending on a chemical equivalent relationship
among Al, N, Mn, and S that are solid-dissolved.
[0076] In the case in which the precipitates are incompletely
solution-treated, sizes of the precipitates are greater than those
in the case in which the precipitates are completely
solution-treated, even though a precipitation amount is large, once
cold rolling is possible.
[0077] On the contrary, in the case in which the precipitates are
completely solution-treated, after hot-rolled sheet annealing heat
treatment, large amounts of nitrides or sulfides are finely formed.
Therefore, once cold rolling, which is a subsequent process, may
not be easy, but in the case in which a precipitation amount of
precipitates is small by the chemical equivalent relationship, the
once cold rolling is possible.
[0078] It is preferable that contents of N and S again
solid-dissolved in fired steel through the reheating of the steel
slab are 20 to 50 ppm and 20 to 50 ppm, respectively. The contents
of N and S that are again solid-dissolved need to consider contents
of Al and Mn contained in the fired steel. The reason is that a
nitride and a sulfide used as a crystal grain growth inhibitor are
(Al,Si,Mn)N, AlN, and MnS.
[0079] A correlation equation in relation to solid solubility of Al
and N of 3% of pure silicon steel sheet has been suggested by
Iwayama and is as follows.
log [ % Al ] [ % N ] = - 10062 1 T ( K ) + 2.72 ##EQU00001##
[0080] For example, when it is assumed that a content of
acid-soluble aluminum is 0.028% and a content of N is 0.0050%, a
theoretical solid-dissolving temperature by the equation suggested
by Iwayama is 1258.degree. C. In order to heat the slab of the
electrical steel sheet as described above, the slab needs to be
heated at 1300.degree. C.
[0081] However, when the slab is heated to 1280.degree. C. or more,
Fayalite corresponding to a compound between silicon having low
melting point and iron, which is a base metal, is produced in the
steel sheet. Therefore, a surface of the steel sheet melts down,
such that hot rolling workability is very difficult, and
maintenance is increased by heating due to the melting-down
iron.
[0082] For the reason described above, that is, the heating, it is
preferable to reheat the slab at a temperature of 1250.degree. C.
or less in order to enable an appropriate control of the
maintenance, cold rolling, and a primary recrystallization texture.
In detail, a temperature at which the slab is reheated may be
900.degree. C. to 1250.degree. C., 900.degree. C. to 1200.degree.
C., 900.degree. C. to 1150.degree. C., 1000.degree. C. to
1250.degree. C., 1100.degree. C. to 1250.degree. C., 1000.degree.
C. to 1250.degree. C., or 1000.degree. C. to 1200.degree. C.
[0083] In addition, Iwayama has suggested a correlation equation in
relation to solid solubility of Mn and S of 3% of pure silicon
steel sheet.
log [ % Mn ] [ % S ] = - 14855 1 T ( K ) + 6.82 ##EQU00002##
[0084] For example, when it is assumed that a content of manganese
is 0.04% and a content of S is 0.004%, a theoretical
solid-dissolving temperature by the equation suggested by Iwayama
is 1126.degree. C. When the slab of the electrical steel sheet as
described above is heated at 1150.degree. C., an Mn-based sulfide
may be completely solution-treated. In addition, when it is assumed
that a content of manganese is 0.06% and a content of S is 0.003%,
a theoretical solid-dissolving temperature is 1130.degree. C.
Therefore, when the slab of the electrical steel sheet is heated at
1150.degree. C., an Mn-based sulfide may be completely
solution-treated.
[0085] However, when it is assumed that a content of manganese is
0.1% and a content of S is 0.003%, a theoretical solid-dissolving
temperature is 1163.degree. C., and when the slab of the electrical
steel sheet is heated at 1150.degree. C., an Mn-based sulfide may
not be completely solution-treated, but may be almost completely
solution-treated.
[0086] A deformed structure stretched in a rolling direction by
stress exits in a hot-rolled sheet, and AlN, MnS, or the like, is
precipitated during the hot rolling. Therefore, in order to have a
uniform recrystallization microstructure and a precipitate
distribution of fine AlN before the cold rolling, the hot-rolled
sheet needs to be heated up to a heating temperature or less of the
slab. It is important to recrystallize the deformed structure
through the heating and secure sufficient austenite phases to
promote solid dissolution of crystal grain growth inhibitors such
as AlN and MnS.
[0087] Therefore, it is preferable that a hot-rolled sheet
annealing temperature is 900 to 1200.degree. C. in order to
maximize a fracture of austenite. In addition, it is preferable to
perform crack heat treatment at the temperature range described
above and then perform cooling. After the hot-rolled sheet
annealing heat treatment to which the heat treatment pattern
described above is applied, an average size of precipitates in a
strip has a range of 200 to 3000 .ANG..
[0088] After the hot-rolled sheet annealing, cold rolling is
performed on the sheet using a reverse rolling mill or a tandem
rolling mill so that the sheet has a thickness of 0.10 mm or more
to 0.50 mm or less. It is preferable to perform once cold rolling
from an initial rolling thickness to a thickness of a final product
without performing annealing heat treatment on a deformed structure
in an intermediate process.
[0089] Orientations of which a degree of integration of a
{110}<001> orientation is low are rotated to deformed
orientations. Therefore, only Goss crystal grains arranged in the
{110}<001> orientation exist in a cold-rolled sheet. In a
two-time or more rolling method, orientations having a low degree
of integration also exist in the cold-rolled sheet. Therefore, the
orientations having the low degree of integration are also
secondarily recrystallized at the time of final annealing, such
that a magnetic flux density and core loss characteristics are
deteriorated. Therefore, it is preferable that the cold rolling is
once steel cold rolling and has a cold rolling ratio of 87% or
more. In detail, the cold rolling ratio may be 87% to 90%, 87% to
91%, 87% to 92%, 87% to 93%, 87% to 94%, 87% to 95%, 87% to 96%,
87% to 97%, 87% to 98%, or 87% to 99%.
[0090] Decarbonization, recrystallization of the deformed
structure, and nitriding using an ammonia gas are performed on the
cold-rolled plate as described above. The decarbonization and
nitriding process may be any one of a method of performing the
nitriding using the ammonia gas after the decarbonization and the
recrystallization end and a method of simultaneously using the
ammonia gas so that the nitriding may be performed simultaneously
with the decarbonization, which does not cause a problem in
exerting an effect of the present invention.
[0091] It is preferable that an annealing temperature of the steel
sheet in performing the decarbonization, the recrystallization, and
the nitriding is in a range of 800 to 950.degree. C. When the
annealing temperature of the steel sheet is lower than 800.degree.
C., it takes a lot of time to perform the decarbonization. When the
annealing temperature of the steel sheet is higher than 950.degree.
C., recrystallized grains are coarsely grown, such that crystal
growth driving force is decreased. Therefore, stable secondary
recrystallization is not formed. In addition, the annealing time is
not a serious problem in exerting the effect of the present
invention, but it is preferable that the annealing time is within 5
minutes in consideration of productivity.
[0092] Immediately before or after the decarburization nitriding
annealing heat treatment ends, a portion or the entirety of an
oxide layer present in an outer oxide layer formed on a surface of
the steel sheet decarbonization-nitriding-annealed may be reduced
and removed under a reducing atmosphere. Then, an annealing
separating agent based on MgO may be applied to the steel sheet,
and final annealing may be performed on the steel sheet for a long
time to generate the secondary recrystallization, thereby forming a
{110}<001> texture in which a {110} surface of the steel
sheet is in parallel with a rolled surface and a <001>
direction is in parallel with a rolling direction. Therefore, the
grain-oriented electrical steel sheet having excellent magnetic
characteristics may be manufactured.
[0093] Main objects of the final annealing are to form the
{110}<001> texture by the secondary recrystallization, give
an insulation property by forming a glass film by an reaction
between the oxide layer formed at the time of decarbonization and
MgO, and remove impurities damaging the magnetic characteristics.
It is preferable that a final annealing temperature is a
decarbonization annealing temperature or more to 1250.degree. C. or
less. In detail, the final annealing temperature may be 800.degree.
C. to 1250.degree. C., 850.degree. C. to 1250.degree. C., or
900.degree. C. to 1250.degree. C. As a final annealing method, an
atmosphere including one or more of nitrogen and hydrogen may be
maintained in a temperature increase section before the secondary
recrystallization is generated.
[0094] Therefore, a nitride, which is a grain growth inhibitor, may
be protected to allow the secondary recrystallization to be grown
well. After the secondary recrystallization is completed, the steel
sheet is maintained for a long time under a 100% hydrogen
atmosphere.
MODE FOR INVENTION
[0095] Hereinafter, Examples of the present invention and
Comparative Examples are described. However, the following Examples
are only exemplary embodiments of the present disclosure, and the
present invention is not limited to the following Examples.
Example 1
[0096] A grain-oriented electrical steel sheet containing 0.004% of
S, 0.0042% of N, 0.028% of Sol-Al, 0.028% of Sb, 0.07% of Sn,
0.028% of P, and 0.03% of C of which a content is changed depending
on contents of Si and Mn as illustrated in Table 1, and containing
balance Fe and other inevitable impurities as the remaining
components was dissolved in a vacuum state, and ingot was produced,
was heated to a temperature of 1150.degree. C., and was then
hot-rolled at a thickness of 2.3 mm. A hot-rolled plate was heated
to a temperature of 1085.degree. C., was maintained at 920.degree.
C. for 160 seconds, and was then quenched in water. The hot-rolled
annealed sheet was pickled and was then rolled once to a thickness
of 0.23 mm, and the cold-rolled sheet was maintained under a mixed
gas atmosphere of humid hydrogen, nitrogen, and ammonia at a
temperature of 860.degree. C. for 200 seconds to perform a
simultaneous decarbonization annealing heat treatment so that a
content of nitrogen is 170 ppm.
[0097] MgO, which is an annealing separating agent, was applied to
the steel sheet to finally anneal the steel sheet, the final
annealing was performed under a mixed atmosphere of 25%
nitrogen+75% hydrogen as a volume ratio at a temperature up to
1200.degree. C., and after a temperature of the steel sheet arrives
at 1200.degree. C., the steel sheet was maintained for 10 or more
hours under a 100% hydrogen atmosphere and was then furnace-cooled.
Measurement values of magnetic characteristics in the respective
conditions are illustrated in Table 1.
TABLE-US-00001 TABLE 1 Core Loss Magnetic Flux Si Mn C (W17/50,
density (wt %) (wt %) (wt %) W/kg) (B10, Tesla) Division 2.56 0.07
0.015 1.3 1.86 Comparative Example 1 2.55 0.11 0.055 1.2 1.85
Comparative Example 2 2.55 0.09 0.042 0.84 1.94 Inventive Example 1
2.88 0.06 0.024 1.24 1.84 Comparative Example 3 2.89 0.11 0.062 1.3
1.86 Comparative Example 4 2.88 0.09 0.045 0.85 1.94 Inventive
Example 2 3.02 0.07 0.025 1.25 1.86 Comparative Example 5 3 0.09
0.062 1.21 1.86 Comparative Example 6 3.03 0.09 0.049 0.82 1.91
Inventive Example 3 3.15 0.07 0.026 1.29 1.84 Comparative Example 7
3.14 0.1 0.065 1.26 1.84 Comparative Example 8 3.15 0.09 0.052 0.83
1.93 Inventive Example 4 3.35 0.06 0.029 1.23 1.82 Comparative
Example 9 3.35 0.09 0.072 1.28 1.83 Comparative Example 10 3.34
0.06 0.058 0.79 1.91 Inventive Example 5 3.55 0.07 0.03 1.29 1.84
Comparative Example 11 3.57 0.09 0.075 1.25 1.84 Comparative
Example 12 3.56 0.09 0.064 0.78 1.9 Inventive Example 6 3.84 0.07
0.029 1.27 1.83 Comparative Example 13 3.82 0.1 0.084 1.2 1.84
Comparative Example 14 3.79 0.09 0.066 0.8 1.9 Inventive Example 7
4.01 0.06 0.025 1.29 1.83 Comparative Example 15 4 0.1 0.085 1.25
1.84 Comparative Example 16 4.02 0.09 0.072 0.77 1.9 Inventive
Example 8
[0098] It may be seen from the above Table 1 that magnetic
characteristics are significantly improved in Inventive Examples in
which -0.32.times.Mn(wt %)+0.012.times.Si(wt %)+0.016.ltoreq.C(wt
%).ltoreq.-0.014.times.Mn(wt %)+0.02.times.Si(wt %) where a content
of C is a content relationship among Si, Mn, and C as compared with
Comparative Examples.
Example 2
[0099] A grain-oriented electrical steel sheet containing 3.35% of
Si, 0.061% of C, 0.058% of Mn, 0.004% of S, 0.004% of N, 0.029% of
Sol-Al, 0.032% of P, and Sn, Sb, and Cr of which contents are
changed as illustrated in Table 2, and containing balance Fe and
other inevitable impurities as the remaining components was
dissolved in a vacuum state, and ingot was produced, was heated to
a temperature of 1140.degree. C., and was then hot-rolled at a
thickness of 2.3 mm. A hot-rolled plate was heated to a temperature
of 1080.degree. C., was maintained at 915.degree. C. for 162
seconds, and was then quenched in water. The hot-rolled annealed
sheet was pickled and was then rolled once to a thickness of 0.23
mm, and the cold-rolled sheet was maintained under a mixed gas
atmosphere of humid hydrogen, nitrogen, and ammonia at a
temperature of 850.degree. C. for 200 seconds to perform a
simultaneous decarbonization annealing heat treatment so that a
content of nitrogen is 180 ppm.
[0100] MgO, which is an annealing separating agent, was applied to
the steel sheet to finally anneal the steel sheet, the final
annealing was performed under a mixed atmosphere of 25%
nitrogen+75% hydrogen as a volume ratio at a temperature up to
1200.degree. C., and after a temperature of the steel sheet arrives
at 1200.degree. C., the steel sheet was maintained for 10 or more
hours under a 100% hydrogen atmosphere and was then furnace-cooled.
Measurement values of magnetic characteristics in the respective
conditions are illustrated in Table 2.
TABLE-US-00002 TABLE 2 Core Loss Magnetic Flux Sn Sb Cr (W17/50,
Density (wt %) (wt %) (wt %) W/kg) (B10, Tesla) Division 0.03 0.01
-- 0.86 1.91 Comparative Example17 0.03 0.01 0.04 0.80 1.93
Inventive Example9 0.03 0.05 0.01 0.83 1.92 Comparative Example18
0.03 0.05 0.04 0.78 1.93 Inventive Example10 0.05 0.01 0.01 0.85
1.92 Comparative Example19 0.05 0.01 0.04 0.78 1.93 Inventive
Example11 0.05 0.05 0.01 0.84 1.91 Comparative Example20 0.05 0.05
0.04 0.79 1.93 Inventive Example12 0.07 0.01 0.01 0.84 1.91
Comparative Example21 0.07 0.01 0.04 0.79 1.94 Inventive Example13
0.07 0.05 0.02 0.84 1.92 Comparative Example22 0.07 0.05 0.05 0.79
1.93 Inventive Example14
[0101] It may be seen from the above Table 2 that magnetic
characteristics are improved in Inventive Examples in which Sn(wt
%)+Sb(wt %).ltoreq.5.times.Cr(wt %) where a content of Cr is a
content relationship among Sn, Sb, and Cr as compared with
Comparative Examples.
[0102] While this invention has been described in connection with
what is presently considered to be practical exemplary embodiments,
it is to be understood that the invention is not limited to the
disclosed embodiments, but, on the contrary, is intended to cover
various modifications and equivalent arrangements included within
the spirit and scope of the appended claims.
* * * * *