KR101665950B1 - Non-oriented electrical steel sheets and method for manufacturing the same - Google Patents

Abstract

A non-oriented electrical steel sheet and a manufacturing method thereof are disclosed. The non-oriented electrical steel sheet according to the present invention contains, by weight percent, 1.5 to 4.0% of Si, 0.0005 to 0.02% of Al, 0.01 to 0.50% of Mn, 0.01 to 0.15% of Sn, 0.15% P: 0.001 to 0.15%, C: 0.004% or less (excluding 0%), N: 0.003% or less (not including 0%), S: 0.0001 to 0.01% [Sn] + [Sb] and [Al] < [Sn] + [Sn] Sn], [Sn], [Sb] and [P] represent weight percentages (%) of Al, Sn, Sb and P, respectively.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-oriented electrical steel sheet,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-oriented electrical steel sheet, and more particularly, to a non-oriented electrical steel sheet having an excellent magnetic property by controlling the component system of the steel sheet.

The nonoriented electric steel sheet is used as an iron core material in rotating devices such as motors, generators, and stationary devices such as small transformers, and plays an important role in determining the energy efficiency of electric devices.

The characteristics of the electric steel sheet include iron loss and magnetic flux density. The iron loss is small and the magnetic flux density is high, which is preferable. When the magnetic field is induced by adding electricity to the iron core, the lower the iron loss, And the higher the magnetic flux density, the larger the magnetic field can be induced with the same energy.

Conventionally, considered as energy loss and magnetic flux density when the magnetization of the magnetic properties of non-oriented electrical steel sheet used for motor iron loss by a W _15/50 as an index in the 50Hz frequency up to 1.5 T by the B ₅₀ as an index 5000A / m. However, magnetic properties in the authors' field are becoming important because in the AC motor driven by the inverter, magnetization occurs because the electric steel sheet has a magnetic flux density of about 1.0 T.

Disclosure of Invention Technical Problem [8] Accordingly, the present invention has been made to solve the above problems, and it is an object of the present invention to provide a non-oriented electrical steel sheet having a low core loss and high magnetic flux density and a method of manufacturing the same.

The non-oriented electrical steel sheet according to one embodiment of the present invention comprises, by weight, 1.5 to 4.0% of Si, 0.003 to 0.011% of Al, 0.01 to 0.50% of Mn, 0.01 to 0.09% of Sn, 0.01 to 0.09% of Sn, : Not more than 0.03% (not including 0%), P: 0.01 to 0.1%, C: not more than 0.004% (not including 0%), N: not more than 0.003% 0.0001 to 0.01%, Ti: 0.003% or less (not including 0%), the balance including Fe and other inevitably added impurities,

The Al, Sn, Sb, and P are

[Al] <[Sn] + [Sb] and [Al] <[Sn] + [P]

(Al, Sn, Sb, and P represent weight percentages (%) of Al, Sn, Sb, and P, respectively).

Further, Sn, Sb and P are

0.03? [Sn] + [Sb] + [P]? 0.30

([Sn], [Sb], and [P] refer to weight percent (%) of Sn, Sb and P, respectively)

Can be satisfied.

Further, the magnetic flux density of the non-oriented electrical steel sheet

B ₁ / B ₁₀ ≥ 0.65.

In addition, the inevitably added impurities include Cu, Ni, Cr, Zr, Mo, and V, and the contents of Cu, Ni, and Cr are each 0.05 wt% or less , And the contents of Zr, Mo, and V are each 0.01 wt% or less (not including 0 wt%).

In addition, the size of the crystal grains in the microstructure of the electrical steel sheet may be 30 to 300 mu m.

A method of manufacturing a non-oriented electrical steel sheet according to an embodiment of the present invention includes: 1.5 to 4.0% of Si, 0.003 to 0.011% of Al, 0.01 to 0.50% of Mn, 0.01 to 0.09% of Sn, P: 0.01 to 0.1%, C: not more than 0.004% (not including 0%), N: not more than 0.003% (not including 0%), Sb: not more than 0.03% , S: 0.0001 to 0.01%, Ti: 0.003% or less (not including 0%), the balance including Fe and other inevitably added impurities,

The Al, Sn, Sb, and P are

[Al] <[Sn] + [Sb] and [Al] <[Sn] + [P]

(Al, Sn, Sb, and P mean the percentages by weight of Al, Sn, Sb, and P, respectively)

Providing a slab that satisfies &lt; RTI ID = 0.0 &gt;

Heating the slab to 1,250 캜 or lower and rolling to produce a hot-rolled steel sheet;

Cold-rolling the hot-rolled steel sheet to produce a cold-rolled steel sheet; And

And finally annealing the cold-rolled steel sheet at 950 to 1,120 占 폚.

The Sn, Sb and P are

0.03? [Sn] + [Sb] + [P]? 0.30

([Sn], [Sb], and [P] refer to weight percent (%) of Sn, Sb and P, respectively)

Can be satisfied.

The method may further include annealing the hot-rolled steel sheet at 950 to 1,200 ° C.

The magnetic flux density of the final annealed steel sheet

B ₁ / B ₁₀ ≥ 0.65.

Wherein the inevitably added impurities include Cu, Ni, Cr, Zr, Mo, and V, and the contents of Cu, Ni, and Cr are each 0.05 wt% or less (do not include 0 wt% The contents of Zr, Mo, and V may each be added in an amount of 0.01 wt% or less (not including 0 wt%).

The size of the crystal grains in the microstructure of the final annealed steel sheet may be 30 to 300 mu m.

The non-oriented electrical steel sheet according to the present invention can optimally control the components of Al, Sn, Sb and P to produce a non-oriented electrical steel sheet having improved iron loss improvement in the autogenous region and improved magnetic properties remarkably.

1 is a view showing magnetic and iron loss characteristics of an electric steel sheet according to an embodiment of the present invention.
2 is a view showing magnetic properties of an electric steel sheet according to an embodiment of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention, and the manner of achieving them, will be apparent from and elucidated with reference to the embodiments described hereinafter in conjunction with the accompanying drawings. However, it is to be understood that the present invention is not limited to the disclosed embodiments, but may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. It is intended that the disclosure of the present invention be limited only by the terms of the appended claims. Like reference numerals refer to like elements throughout the specification.

Hereinafter, a non-oriented electrical steel sheet according to a preferred embodiment of the present invention will be described.

The non-oriented electrical steel sheet according to the present invention contains, by weight percent, 1.5 to 4.0% of Si, 0.003 to 0.011% of Al, 0.01 to 0.50% of Mn, 0.01 to 0.09% of Sn, 0.03% P: 0.01 to 0.1%, C: not more than 0.004% (not including 0%), N: not more than 0.003% (not including 0%), S: 0.0001 to 0.01% Ti: not more than 0.003% (not including 0%), the balance including Fe and other inevitably added impurities

The Al, Sn, Sb, and P are

[Al] <[Sn] + [Sb] and [Al] <[Sn] + [P]

(Al, Sn, Sb, and P mean the percentages by weight of Al, Sn, Sb, and P, respectively)

.

Further, Sn, Sb and P are

0.03? [Sn] + [Sb] + [P]? 0.30

([Sn], [Sb], and [P] refer to weight percent (%) of Sn, Sb and P, respectively)

Can be satisfied.

The reasons for limiting the content of the non-oriented electrical steel sheet according to the present invention are as follows.

Si: 1.5 to 4.0 wt%

If the Si content is less than 1.5%, it is difficult to obtain a low iron loss characteristic. If the Si is annealed at a temperature of 1000 ° C or more, a problem of phase transformation occurs and a Si content of 4.0% , The rolling property is deteriorated. Therefore, in the present invention, Si is limited to 1.5 to 4.0 wt%.

Mn: 0.01 to 0.50 wt%

Since the Mn has the effect of increasing the specific resistance and lowering the iron loss in addition to Si and Al, the conventional unoriented electric steel sheet was attempted to improve the iron loss by adding at least 0.05% of Mn. However, as the Mn addition amount increased, the saturation magnetic flux density decreased Therefore, the magnetic flux density when a constant current is applied decreases.

Therefore, in order to improve the magnetic flux density and prevent the increase of iron loss due to inclusions, the amount of Mn added is limited to 0.01 to 0.50%, more preferably 0.05 to 0.30%.

Al: 0.003 to 0.011 wt%

Al is an element which is inevitably added for deoxidizing steel in the steelmaking process. In general steel making process, 0.01% or more of Al is present in the steel. However, when added in large amounts, the saturation magnetic flux density is reduced and fine AlN is formed to suppress the grain growth, thereby lowering the magnetic property, so it is limited to 0.003 to 0.011%.

P: 0.01 to 0.1 wt%

The P decreases the iron loss by lowering the specific resistance and segregates in the grain boundaries to inhibit the formation of {111} texture which is harmful to the magnetism and forms {100} which is an advantageous aggregate structure. However, 0.1% by weight. In addition, P is an element that lowers the surface energy of the {100} surface in the steel sheet surface, and the amount of P segregated on the surface is increased by containing the P content in a larger amount, thereby further lowering the surface energy of the {100} It is possible to improve the growth rate of crystal grains having a {100} face favorable to magnetism during annealing.

C: not more than 0.004% by weight

C increases the austenite area when it is added a lot and increases the phase transformation period. However, it shows an effect of increasing the iron loss by suppressing the crystal growth of ferrite during annealing, and also forming a carbide by binding with Ti etc., When used as a product after processing, iron loss is increased by magnetic aging, so it should be 0.004% or less.

S: 0.0001 to 0.01 wt%

S is an element which forms sulfides such as MnS, CuS and (Cu, Mn) S which are harmful to the magnetic properties, and therefore it is known that it is preferable to add S low to suppress an increase in iron loss. However, when S is segregated on the surface of the steel, it has the effect of lowering the surface energy of the {100} plane. Therefore, by adding S, a texture having strong {100} plane can be obtained. However, when it is added in an amount exceeding 0.010%, the workability is significantly lowered due to segregation of crystal grain boundaries, and a problem due to surface segregation occurs. Therefore, the addition amount is limited as described above.

N: not more than 0.003% by weight

N is an element harmful to magnetism, such as nitrides being strongly bonded with Al, Ti or the like to inhibit crystal growth, and therefore it is preferable to contain N in a small amount. In the present invention, N is limited to 0.003 wt% or less.

Ti: 0.003 wt% or less

Ti forms fine carbides and nitrides to inhibit crystal growth. As the amount of Ti is increased, the crystallinity is lowered due to the increased carbides and nitrides, and the magnetism deteriorates. Therefore, the Ti content is limited to 0.003% or less in the present invention.

0.03? [Sn] + [Sb] + [P]? 0.30 where [Sn], [Sb] and [P] represent the weight percent (%) of Sn, Sb and P, respectively.

The above Sn, Sb and P suppress the diffusion of nitrogen through the grain boundaries as a segregated element in the grain boundaries and control the grain boundary moving speed during the final annealing to help grow the grain favorable to the magnetism, Thereby imparting high magnetic flux density characteristics. At this time, when Sn, Sb and P are added alone or in a total amount exceeding 0.30%, crystal grain growth is inhibited and iron loss is greatly increased, and the amount of precipitation is greatly increased to increase iron loss. In addition, It is limited to 0.03? [Sn] + [Sb] + [P]?

Wherein the contents of Cu, Ni and Cr are added in an amount of 0.05 wt% or less, respectively, and the content of Zr, Mo and V is 0.01% by weight or less.

Since the Cu, Ni and Cr are inevitably added in the steel making process, Cu, Ni and Cr react with the impurity elements to form fine sulfides, carbides and nitrides, which are harmful to the magnetic properties. 0.05% by weight or less.

Further, Zr, Mo, V and the like are preferably strong carbonitride-forming elements, so that they are preferably not added, and they are contained in an amount of 0.01 wt% or less.

In addition to the above composition, the remainder include Fe and other unavoidable impurities that can be added in the steel making process.

In the present invention, Al, Sn, Sb and P are controlled as follows.

[Al] < [Sn] + [Sb] and [Al] < [Sn] + [P] where Al, Sn, Sb and P are Al, Sn, Sb and P % &Lt; / RTI &gt; by weight)

When the addition amount of Al is larger than the total amount of Sn and Sb or the total amount of Sn and P, a structure unfavorable to magnetism is formed.

The magnetic flux density of the non-oriented electrical steel sheet is B ₁ / B ₁₀ ≥ 0.65 can be satisfied.

The non-oriented electrical steel sheet excellent in magnetic properties in the author field has a particularly high magnetic flux density in a low magnetic field. Therefore, when B ₁ / B ₁₀ is less than 0.65, the magnetic property has a property of heating at a low magnetic field of 100 A / m.

The contents of Cu, Ni and Cr are added in an amount of 0.05 wt% or less, respectively, and the content of Zr, Mo and V is Each may be 0.01% by weight or less.

In addition, the size of the crystal grains in the microstructure of the electrical steel sheet may be 30 to 300 mu m.

If the grain size is less than 30 탆, hysteresis is greatly increased and the iron loss is deteriorated. If the grain size exceeds 300 탆, there is a problem in machining at the time of punching in a product coated after annealing.

Hereinafter, a method for manufacturing a non-oriented electrical steel sheet according to another embodiment of the present invention will be described.

A method for producing a non-oriented electrical steel sheet according to the present invention is a method for producing a non-oriented electrical steel sheet which comprises 1.5 to 4.0% of Si, 0.003 to 0.011% of Al, 0.01 to 0.50% of Mn, 0.01 to 0.09% of Sn, 0.01 to 0.09% of Sn, P: 0.01 to 0.1%, C: not more than 0.004% (not including 0%), N: not more than 0.003% (not including 0%), S: 0.0001 To 0.01%, Ti: 0.003% or less (not including 0%), the balance including Fe and other inevitably added impurities,

The Al, Sn, Sb, and P are

[Al] <[Sn] + [Sb] and [Al] <[Sn] + [P]

Sn, Sb and P, wherein [Al], [Sn], [Sb], and [P] refer to weight percentages (%) of Al, Sn, Sb and P, respectively.

Heating the slab to 1,250 캜 or lower and rolling to produce a hot-rolled steel sheet;

Cold-rolling the hot-rolled steel sheet to produce a cold-rolled steel sheet; And

And finally annealing the cold-rolled steel sheet at 950 to 1,120 占 폚.

Further, Sn, Sb and P are

0.03? [Sn] + [Sb] + [P]? 0.30

([Sn], [Sb], and [P] refer to weight percent (%) of Sn, Sb and P, respectively)

Can be satisfied.

(%), Si: 1.5 to 4.0%, Al: 0.003 to 0.011%, Mn: 0.01 to 0.50%, Sn: 0.01 to 0.09%, Sb: 0.03% 0.003% or less (excluding 0%), S: 0.0001-0.01%, Ti: 0.003% or less (0% or less) , The remainder including Fe and other inevitably added impurities,

The Al, Sn, Sb, and P are

[Al] <[Sn] + [Sb] and [Al] <[Sn] + [P]

(Here, [Al], [Sn], [Sb], and [P] refer to weight percent (%) of Al, Sn, Sb and P, respectively) Rolled to produce a hot-rolled steel sheet.

When the heating temperature is higher than 1,250 DEG C, precipitates such as AlN and MnS existing in the slab are reused and then precipitated by hot rolling to inhibit grain growth and decrease magnetism, so that the reheating temperature is limited to 1,250 DEG C or less.

Finishing rolling in hot rolling in finish rolling finishes in the ferrite phase region.

Further, it is possible to add a large amount of ferrite-like expanded elements such as Si, Al, P or the like during hot rolling, or to contain Mn, C and the like which are elements to suppress the ferrite phase.

As described above, when rolled on ferrite, a large number of {100} planes are formed in the texture, thereby improving the magnetic properties.

In addition, the final reduction ratio can be reduced to 20% or less for plate shape calibration.

The hot-rolled steel sheet thus produced is rolled up at a temperature of 750 ° C or lower and cooled in air.

The wound hot-rolled steel sheet may further include annealing the hot-rolled steel sheet.

The hot-rolled sheet annealing is carried out at 950 to 1200 ° C for improving the magnetic properties.

If the annealing temperature of the hot-rolled sheet is lower than 950 ° C, grain growth is insufficient. If the annealing temperature exceeds 1200 ° C, crystal grains excessively grow and surface defects of the plate become excessive.

The hot rolled sheet is pickled and cold rolled.

Cold rolling can be finally rolled to a thickness of 0.50 mm or less. If necessary, it can be subjected to primary cold rolling and intermediate annealing, followed by secondary cold rolling, and the final rolling reduction can be in the range of 50 to 95%.

The cold-rolled steel sheet is subjected to cold-rolled sheet annealing (finish annealing). In the step of annealing the cold-rolled sheet, the temperature of the cracking of the cold-rolled sheet during annealing (finish annealing) is 950 to 1120 캜.

When the annealing temperature of the cold-rolled sheet is lower than 950 ° C, it is difficult to realize the process because of a long time required to obtain crystal grains of sufficient size to obtain low iron loss. When the temperature is higher than 1,120 ° C, the plate phase during annealing is uneven and the precipitates are re- It may be finely precipitated during cooling to adversely affect magnetism.

The cold rolled annealed sheet may be subjected to an insulating coating treatment.

Hereinafter, a method of manufacturing a non-oriented electrical steel sheet according to the present invention will be described in detail with reference to examples. The following examples are illustrative of the present invention only and are not intended to limit the scope of the present invention.

&Lt; Example 1 >

A slab having the composition shown in Table 1 was heated at 1,150 占 폚, hot-rolled to a thickness of 2.5 mm, and wound at 650 占 폚. The hot-rolled steel sheet cooled in air was annealed at 1,080 ° C for 3 minutes, pickled and cold-rolled to a thickness of 0.35 mm, and subjected to final annealing at 1,050 ° C for 1 minute.

Using a single piece with respect to the magnetic measurement taken at least 5 specimens for each sample W _15/50 iron loss, and B _1, B _10, B ₅₀ by measuring the magnetic flux density are shown in Table 2. The results are.

Steel grade Si Mn P Al Sn Sb C N S Ti P1 3.3 0.3 0.005 1.2 0.021 - 0.003 0.002 0.0034 0.001 P2 3.1 0.25 0.02 0.8 0.037 - 0.004 0.002 0.0057 0.002 P3 3.0 0.15 0.01 0.5 0.018 - 0.003 0.003 0.0027 0.002 P4 2.8 0.15 0.005 0.4 - - 0.003 0.002 0.0016 0.002 P5 2.6 0.4 0.01 0.4 - - 0.002 0.005 0.0023 0.003 P6 2.4 0.15 0.03 0.3 - - 0.003 0.002 0.0035 0.001 P7 2.2 0.2 0.02 0.3 - - 0.003 0.001 0.011 0.002 T1 3.1 0.2 0.03 0.005 0.05 0.02 0.002 0.002 0.0039 0.001 T2 3.0 0.25 0.05 0.003 0.03 0.01 0.003 0.002 0.0061 0.002 T3 2.0 0.2 0.01 0.005 0.09 - 0.002 0.003 0.0057 0.002 T4 2.9 0.05 0.05 0.01 0.05 - 0.003 0.002 0.0043 0.001 T5 2.4 0.15 0.06 0.009 0.02 0.03 0.002 0.001 0.0023 0.002 T6 2.5 0.2 0.1 0.011 0.04 0.01 0.003 0.002 0.0014 0.001 T7 2.7 0.3 0.02 0.005 0.06 0.03 0.002 0.002 0.0058 0.002 T8 1.5 0.2 0.07 0.003 0.01 - 0.003 0.001 0.0081 0.001

In Table 1, the unit of the component content is% by weight.

Steel grade B ₁ B ₁₀ B ₅₀ B ₁ / B ₁₀ W _15/50 Remarks P1 0.9 1.43 1.64 0.629 2.0 Comparative Example P2 0.91 1.485 1.67 0.613 2.05 Comparative Example P3 0.92 1.49 1.68 0.617 2.2 Comparative Example P4 0.93 1.51 1.69 0.616 2.45 Comparative Example P5 0.93 1.47 1.7 0.633 2.6 Comparative Example P6 0.94 1.485 1.71 0.633 2.85 Comparative Example P7 0.94 1.48 1.72 0.635 3.15 Comparative Example T1 1.14 1.53 1.724 0.745 1.96 Honor T2 1.2 1.55 1.741 0.774 1.94 Honor T3 1.06 1.62 1.8 0.654 2.45 Honor T4 0.99 1.49 1.705 0.664 1.93 Honor T5 1.09 1.58 1.77 0.690 2.06 Honor T6 1.075 1.6 1.778 0.672 2.12 Honor T7 1.08 1.585 1.768 0.681 2.1 Honor T8 1.05 1.6 1.78 0.656 2.7 Honor

1) _Iron loss (W _15/50 ) is the average loss (W / kg) in the rolling direction and in the rolling direction perpendicular to the magnetic flux density of 1.5 Tesla at 50 Hz frequency.

2) The magnetic flux density values (B ₁ , B ₁₀ , and B ₅₀ ) are the average magnetic flux density in the rolling direction and in the direction perpendicular to the rolling direction when a magnetic field of 100 A / m, 1000 A / m, )being.

[Sn] + [Sb], [Al] <[Sn] + [P] and [Sn] + [Sb] + [P] were 0.03% or more and 0.30% or less.

In addition, the specimen of the invention example satisfies [Al] < 0.015% or less, and the specimen of the comparative example has not less than 0.3% of [Al].

The effect of the present invention is shown in Fig. The y-axis B ₁ as measured at 50Hz alternating magnetic flux density value of the magnetizing force 100A / m in the rolling direction and rolling direction perpendicular to display the average value and the x axis shows the specimen at the time of magnetization by a sine wave at 50Hz AC to 1.5T It showed a loss of energy per weight caused W _15/50. W _15/50 invention in comparison with the re-invention material having a core loss material than the comparative material B ₁ is similar to the effect of the present invention was higher than 0.2T to 0.05T higher for at least up to.

The effect of the invention is also shown in Fig. The y-axis is B ₁ / B ₁₀ and the x-axis is B ₅₀ . The magnetic flux density values B ₁ , B ₁₀ and B ₅₀ were obtained by averaging magnetic flux density values measured at magnetizing forces of 100 A / m, 1000 A / m and 5000 A / m at 50 Hz alternating current in both the rolling direction and the rolling direction. 1.7 T or more, and B ₁ / B ₁₀ is 0.65 or more.

While the present invention has been described in connection with certain exemplary embodiments, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined by the appended claims.

It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive. The scope of the present invention is defined by the appended claims rather than the detailed description, and all changes or modifications derived from the meaning and scope of the claims and their equivalents should be interpreted as being included in the scope of the present invention .

Claims (7)

(%), Si: 1.5 to 4.0%, Al: 0.003 to 0.011%, Mn: 0.01 to 0.50%, Sn: 0.01 to 0.09%, Sb: 0.03% 0.003% or less (excluding 0%), S: 0.0001-0.01%, Ti: 0.003% or less (0% or less) , The remainder including Fe and other inevitably added impurities,
The Al, Sn, Sb, and P are
[Al] <[Sn] + [Sb] and [Al] <[Sn] + [P]
(Al, Sn, Sb, and P mean the percentages by weight of Al, Sn, Sb, and P, respectively)
Lt; / RTI &gt;
The Sn, Sb and P are
0.03? [Sn] + [Sb] + [P]? 0.30
([Sn], [Sb], and [P] refer to weight percent (%) of Sn, Sb and P, respectively)
Lt; / RTI &gt;
The size of the crystal grains in the microstructure of the electric steel sheet is 30 to 300 mu m,
The magnetic flux density is B ₁ / B ₁₀ ≥ 0.65. delete The method according to claim 1,
Wherein the inevitably added impurities include Cu, Ni, Cr, Zr, Mo, and V, and the contents of Cu, Ni, and Cr are each 0.05 wt% or less (do not include 0 wt% Wherein the contents of Zr, Mo and V are respectively 0.01% by weight or less (not including 0% by weight). (%), Si: 1.5 to 4.0%, Al: 0.003 to 0.011%, Mn: 0.01 to 0.50%, Sn: 0.01 to 0.09%, Sb: 0.03% 0.003% or less (excluding 0%), S: 0.0001-0.01%, Ti: 0.003% or less (0% or less) , The remainder including Fe and other inevitably added impurities,
The Al, Sn, Sb, and P are
[Al] <[Sn] + [Sb] and [Al] <[Sn] + [P]
(Al, Sn, Sb, and P mean the percentages by weight of Al, Sn, Sb, and P, respectively)
Lt; / RTI &gt;
The Sn, Sb and P are
0.03? [Sn] + [Sb] + [P]? 0.30
([Sn], [Sb], and [P] refer to weight percent (%) of Sn, Sb and P, respectively)
Providing a slab that satisfies &lt; RTI ID = 0.0 &gt;
Heating the slab to 1,250 캜 or lower and rolling to produce a hot-rolled steel sheet;
Cold-rolling the hot-rolled steel sheet to produce a cold-rolled steel sheet; And
And finally annealing the cold-rolled steel sheet at 950 to 1,120 占 폚,
The size of the grain in the microstructure of the final steel sheet subjected to the final annealing is 30 to 300 탆 and the magnetic flux density is B ₁ / B ₁₀ ≥ 0.65. &Lt; / RTI &gt; 5. The method of claim 4,
Further comprising a step of annealing the hot-rolled steel sheet at 950 to 1,200 ° C for hot-rolled steel sheet. delete 6. The method of claim 5,
Wherein the inevitably added impurities include Cu, Ni, Cr, Zr, Mo, and V, and the contents of Cu, Ni, and Cr are each 0.05 wt% or less (do not include 0 wt% Wherein the contents of Zr, Mo and V are respectively 0.01% by weight or less (not including 0% by weight).

Images