KR20140058936A - Oriented electrical steel sheets and method for manufacturing the same - Google Patents

Abstract

Disclosed is a method for manufacturing an oriented electrical steel sheet. The method for manufacturing the oriented electrical steel sheet according to the present invention includes a step which reheats a slab comprising 2.0-4.0 wt% of Si, 0.01-0.04 wt% of acid soluble Al, 0.20 wt% or less of Mn, 0.005 wt% or less of N, 0.005 wt% or less of S, 0.005 wt% or less of C, 0.001-1.0 wt% of Ni, and the rest consisting of Fe and other inevitable impurities; a step which hot-rolls the reheated slab; a step which anneals the hot-rolled steel sheet manufactured by hot-rolling; a step which cold-rolls the annealed hot-rolled steel sheet; a step which recrystallization-anneals and nitrogen-anneals the cold-rolled steel sheet; and a step which hot-anneals the recrystallization-annealed and nitrogen-annealed steel sheet.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a directional electric steel sheet,

The present invention relates to a grain-oriented electrical steel sheet and a method for producing the same, and more particularly, to a grain-oriented electrical steel sheet having improved productivity and magnetic properties by increasing the rate of increase in the temperature of high-temperature annealing, and a method for producing the same.

Generally, the grain oriented electrical steel sheet has a so-called Goss texture in which the orientation of all the grains on the steel sheet face is {110} plane and the crystal orientation in the rolling direction is parallel to the <001> axis, Is a soft magnetic material having excellent magnetic properties.

Such a directional electrical steel sheet is rolled to a final thickness of 0.20 to 0.35 mm through hot rolling, hot-rolled sheet annealing, and cold rolling after slab reheating, and then subjected to high-temperature annealing for primary recrystallization annealing and secondary recrystallization.

At this time, it is known that, at a high temperature annealing, the degree of integration of the Goss orientation to be secondary recrystallized becomes higher as the temperature increase rate is slower, and the magnetism is excellent. Usually, the rate of temperature increase during high-temperature annealing of the grain-oriented electrical steel sheet is 15 ° C or less per hour, which is the most energy-consuming process since it takes 2 to 3 days to raise the temperature.

As described above, the high-temperature annealing process for a long-term secondary recrystallization with extremely low productivity remains a problem that is not improved even after long-term research.

In this connection, Japanese Patent Registration No. 0797997 discloses a method of increasing the temperature increase rate at high temperature annealing by applying a heating rate by dividing a section according to temperature. However, since the temperature raising rate up to 950 占 폚 is high but between 950 占 폚 and 1200 占 폚, the temperature raising rate is maintained at the original temperature of 15 占 폚 / h, so that no shortening of the process time occurs between 950 占 폚 and 1200 占 폚 The shortening of the entire process time can not be said to be large.

In addition, since the high temperature annealing process is a batch type in which the entire coil is heated instead of a continuous type, it is very difficult to maintain the center and outer portions of the coil at the same temperature.

Therefore, since the heating rate is changed at a temperature lower than 950 deg. C, the temperature of the outer periphery is higher than 950 deg. C, so that the heating rate is unevenly applied to the entire coil. As a result, it may be a cause of magnetic deterioration and it may be difficult to operate. Therefore, it is necessary to study the process conditions in which the heating rate is constantly high during annealing at high temperature.

As another example, in Japanese Laid-Open Patent Application No. 1997-194943, an inhibiting force at around 1000 ° C, which is the initial stage of the secondary recrystallization, is given by using an element such as V, Nb and Hf as a secondary inhibitor while using AlN as the primary inhibitor , Which shows stable magnetism even when the heating rate is 50 ° C / h.

In other words, it is explained that Hf plays a role in the growth of the Goss bearing lips at a high heating rate because it is segregated especially at the secondary grain boundary and has a slow diffusion rate. However, in this case, the effect at a heating rate of 50 DEG C / h or more is not clear, and addition of an additional inhibitor element results in difficulty in the annealing annealing, so that iron loss can be reduced and Hf is classified as a rare earth metal There is a problem that the manufacturing cost is increased because the price is very high.

As another example, Japanese Laid-Open Patent Application No. 1998-176221 proposes a method for improving the magnetic properties by adjusting the size of the primary recrystallized grains and optimizing the rate of temperature increase at 800 to 1100 ° C for high-temperature annealing. For example, in the range of the size D of the primary recrystallized grains in the range of 5 to 30 um, the rate of temperature increase per hour of the temperature section H is proposed as the following equation.

0.6D (um) + 2 = H (占 폚 / h) = 0.4D (um) +18

According to the above equation, if the size of the first recrystallized grain is 30 μm, the rate of temperature rise is the fastest. However, since the maximum allowable grain size in this equation is 30 mu m, the maximum heating rate is 30 deg. C / h, which means that the effect of improving the heating rate is not significant.

SUMMARY OF THE INVENTION The present invention has been made to solve such problems, and it is an object of the present invention to provide a method of manufacturing a steel sheet, which comprises forming a large and uniform primary recrystallization at a high temperature without controlling the composition of the slab, The present invention provides a method of manufacturing a directional electrical steel sheet in which magnetic properties and productivity are improved by increasing the starting temperature of secondary recrystallization and a directional electrical steel sheet.

A method for producing a grain-oriented electrical steel sheet according to an embodiment of the present invention comprises: 2.0 to 4.0% of Si; 0.01 to 0.04% of an acid soluble Al; 0.20% or less of Mn; 0.005% or less of N , S: not more than 0.005%, C: not more than 0.005%, Ni: 0.001 to 1.0%, and remainder Fe and other unavoidable impurities; reheating the reheated slab to a temperature range of 1,050 to 1,150 캜 A step of subjecting the hot-rolled steel sheet to cold rolling, annealing the cold-rolled sheet by recrystallization annealing, and nitriding annealing; And subjecting the steel sheet subjected to recrystallization annealing and nitriding annealing to high temperature annealing.

And a step of annealing the hot-rolled steel sheet by hot-rolling.

The high-temperature annealing may be performed at a heating rate of 100 to 300 ° C / h at a starting temperature of 1,150 ° C.

The hot rolling step may be performed at a temperature ranging from 1,050 to 1,150 DEG C, and the cumulative rolling reduction may be 30% or more.

The recrystallization annealing is performed at 840 to 880 ° C within 1 minute, and the nitriding annealing can be performed at 860 to 900 ° C.

The size of the recrystallized grains after the recrystallization annealing and nitriding annealing may be 20 to 35 μm and the ratio of the number of crystal grains in the (411) <001> orientation to the crystal grains in the (111) <112> orientation may be 1.0 or more, The standard deviation of grain size after recrystallization annealing and nitriding annealing may be 12.0 or less.

The grain-oriented electrical steel sheet according to one embodiment of the present invention is composed of 2.0 to 4.0% of Si, 0.01 to 0.04% of Al, 0.01 to 0.04% of Mn, 0.006% or less of N, 0.006% or less, C: less than 10 ppm, Ni: 0.001 to 1.0%, the balance Fe and other unavoidable impurities.

According to one embodiment of the present invention, the content of C is controlled to be low in the steelmaking step and Ni is added up to 1% to omit the decarburization process, and the primary recrystallization temperature is raised to make the primary recrystallization grain large and uniform Since the heating rate can be increased in the final high-temperature annealing step, productivity and magnetism can be improved at the same time.

FIG. 1 is a graph showing a change in size of a specific bearing fraction in a directional electrical steel sheet according to a carbon content in a directional steel sheet according to an embodiment of the present invention. FIG.
2 is a scanning electron micrograph (SEM) photograph of the surface of a hot rolled steel plate according to a change in carbon content in a directional electric steel sheet according to an embodiment of the present invention.
3 is a scanning electron microscope (SEM) photograph of the surface of the hot-rolled annealed sheet according to the change in the carbon content of the carbon steel sheet in the method for producing a grain-oriented electrical steel sheet according to an embodiment of the present invention.
FIG. 4 is a graph showing changes in magnetic flux density according to Ni content in the method of manufacturing a grain-oriented electrical steel sheet according to an embodiment of the present invention, (411) / (111) And the distribution of the distribution.

BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention and the manner of achieving them will become apparent with reference to the embodiments described in detail below with reference to 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.

An embodiment according to the present invention is characterized in that it comprises: 2.0 to 4.0% by weight of Si, 0.01 to 0.04% by weight of Al, 0,01 to 20% of Mn, 0.005% or less of N, 0.005% or less of C, 0.001 to 1.0% of Ni, and the balance Fe and other unavoidable impurities.

In one embodiment of the present invention, the slab having the above composition is heated, hot rolled, hot rolled sheet annealed, cold rolled, recrystallization annealed and steep annealed in a mixed gas atmosphere of ammonia, hydrogen and nitrogen , And then high temperature annealing is performed.

In order to form a uniform thermoelectric texture, the hot rolling is carried out by setting the cumulative rolling reduction rate to 30% or more in a high temperature region of 1000 ° C or more, reducing the amount of carbon steel, omitting the decarburization process in the annealing process, It is possible to increase the temperature raising rate in the temperature rising section of the high temperature annealing to 50 to 300 占 폚 / h.

When the method of omitting decarburization by reducing the content of carbon black to 100 ppm is applied, the rate of temperature increase of high temperature annealing can be drastically reduced. However, when the carbon content is less than 100 ppm, the magnetic flux density sharply drops. The cause may be orientation in recrystallization, changes in the distribution of crystal grains, and the like.

FIG. 1 is a graph showing a change in size of a specific bearing fraction in a directional electrical steel sheet according to a carbon content in a directional steel sheet according to an embodiment of the present invention. FIG. As shown in FIG. 1, it can be seen that as the content of carbon black decreases from 100 ppm, (411) the fraction of the bearing sharply decreases and the (111) <112> bearing fraction increases. That is, the (411) orientation which is favorable for the growth of the (110) orientation crystal grains, which is the Goss orientation, is decreased, and the magnetic properties of the final secondary recrystallization grains are weakened.

2 is a scanning electron micrograph (SEM) photograph of the surface of a hot rolled steel plate according to a change in carbon content in a directional electric steel sheet according to an embodiment of the present invention. 3 is a scanning electron microscope (SEM) photograph of the surface of the hot-rolled annealed sheet according to the change in the carbon content of the carbon steel sheet in the method for producing a grain-oriented electrical steel sheet according to an embodiment of the present invention. In the case where the content of carbon black is extremely low, a long band-shaped drawn lips are developed very strongly at the center of the steel sheet as shown in Figs. 2 and 3. On the other hand, even when only 100 ppm of carbon black is added, Can be seen. In addition, when the hot-rolled sheet annealing is carried out, it is confirmed that the coarse crystal grains in the central portion disappear. As can be seen from FIGS. 1 to 3, when the carbon content is less than 100 ppm, it can be considered that the magnetic flux density is decreased due to the decrease of the beneficial crystal grains and the increase of the grain size, such as (411).

FIG. 4 is a graph showing changes in magnetic flux density according to Ni content in the method of manufacturing a grain-oriented electrical steel sheet according to an embodiment of the present invention, (411) / (111) And the distribution of the distribution. In Fig. 4, the content of Ni is a weight percentage (wt%). In FIG. 4, it can be seen that when the proper amount of Ni is added, not only the distribution of the primary recrystallized grains becomes narrower but also the fraction of crystal grains in the (411) orientation increases and the magnetic flux density increases. In this case, the orientation crystal grain fraction value of (411) / (111) <112> orientation is preferably 1.0 or more.

That is, it can be seen that not only the distribution of the primary recrystallized grains but also the fraction of the crystal grains in the (411) orientation plays an important role in the growth of Goss crystal grains.

According to the Coincidence Site Lattice Boundary (CSL) theory proposed by Harase et al., Which relates to the selective growth of Goss grains, there is a relatively large amount of CSL grain around the grain growing from the oriented electrical steel sheet to the secondary recrystallized grains. It is known that the same special grain boundary moves faster than other grain boundary. CSL is a special grain boundary of low energy state that satisfies the coincidence site condition from the specific orientation relationship between grains in grain boundaries.

Whether a grain boundary is a special grain boundary in a tetragonal system is determined by the following equation.

In the above formula, x and y are integers of? 0, and U, V and W are Miller indices indicating the crystal orientation of the rotation axis common to the two particles.

Since all the boundaries can not satisfy the correct CSL relationship, it is necessary to define a tolerance limit for the angular deviation that can be classified as CSL. In general, the following criteria apply.

Also, the following deviation matrix (M _DRV ) is calculated to know what the boundary is.

Where is the disorientation matrix and is the matrix of the angle / axis of each CSL. If the thus obtained offset angle is within the range, the irradiated grain boundaries are classified as grain boundary.

Σ1 means a low angle grain boundary with an angle difference of less than 15 degrees between the two egg arrays. It is the case that the atomic arrangement of the Σ3 inlet egg is rotated by 60 degrees. In this case, one lattice site overlaps three atoms.

The number of lattices overlapping at an angle decreases as the value of the number increases, such as one for each Σ5 and one for each of seven for Σ7.

In CSL grain boundaries, Σ9 grain boundaries with low exponents except Σ1 and Σ3 play a major role in the growth of the (110) [001] orientation by secondary recrystallization, and the frequency of Σ grain boundaries and the frequency of (110) <001> Selective secondary recrystallization occurs in the (110) < 001 > orientation only when the product of the first and second phases exceeds the threshold value.

However, since the (411) orientation is more precisely in the Σ9 relation than the (111) <112> orientation among the Σ9 related orientations, the more the (411) orientation is, the more sharp the Goss is, Secondary recrystallization is produced.

The value of the standard deviation of the grain size in the primary re-crystallization plate may be less than or equal to 12.0. The lower the standard deviation of the grain size, the more complete the structure is.

Hereinafter, the reason for limiting the components of the slab in one embodiment according to the present invention will be described. Unless otherwise stated, the content means weight percent (wt%).

Si: 2.0 to 4.0%

Si lowers the magnetic anisotropy of the material of the electric steel sheet and increases the resistivity, thereby lowering the iron loss. If the Si content is less than 2.0%, the reduction of the resistivity is not so large, and the iron loss becomes low. When the Si content is more than 4.0%, the brittleness increases and the cold rolling becomes difficult.

Acid soluble Al: 0.01 to 0.04%

Al forms a nitride of AlN type and functions as an inhibitor. When the content is not more than 0.01%, sufficient effect can not be obtained. When the content is too high, the nitride precipitates and grows coarsely. Therefore, the content of Al is limited to 0.01 to 0.04%.

Mn: not more than 0.2% (excluding 0%)

Mn plays the role of increasing the resistivity as Si and promotes the austenite transformation during the heating of the slab, thereby facilitating the employment of AlN. When Mn is added in an amount of 0.2% or more, austenite phase transformation occurs, secondary recrystallization does not occur, and the content of Mn is limited to 0.2% or less because cold rolling is difficult.

N: 0.005% or less

When N is contained in an amount of 0.005% or more at the steelmaking stage, the size of the primary recrystallized grains becomes small and the secondary recrystallization starting temperature is lowered to deteriorate the magnetic properties. Therefore, the N content is limited to 0.005% or less.

C: not more than 0.005%

C is an element which has an effect of increasing the austenite fraction during hot rolling to make the hot-rolled structure finer. However, in one embodiment of the present invention, the uniformity due to the primary recrystallized grains obtained by omitting decarburization Since the advantage is larger, it is limited to 0.005% or less.

Ni: 0.001% to 1.0%

Ni has an effect of breaking down the elongation at the center of the hot-rolled sheet and making the hot-rolled structure finer and homogenous, thereby improving the primary recrystallization distribution and increasing the orientation fraction (411). On the other hand, The secondary recrystallization is formed and an excessive amount of austenite phase due to the phase transformation during the secondary recrystallization is formed, so that secondary recrystallization is not formed. Therefore, the secondary recrystallization is limited to 0.001% or more and 1.0% or less.

S: not more than 0.005%

S is effective as an inhibitor for inhibiting grain growth by binding with MnS, but when added excessively, S is segregated at the center of the slab and adversely affects the microstructure. Further, it forms a coarse precipitate by binding with Mn and interferes with the formation of the secondary recrystallized grains, so it is limited to 0.005% or less.

Hereinafter, a method of manufacturing a directional electrical steel sheet according to an embodiment of the present invention will be described.

In one embodiment of the present invention, the steel sheet contains 2.0 to 4.0% of Si, 0.01 to 0.04% of Al, 0.01 to 0.04% of Mn, 0.005% or less of N, 0.005% or less of S, , Ni: 0.001 to 1.0%, and the balance Fe and other unavoidable impurities.

Thereafter, the slabs of the above composition range are reheated to an incomplete solution temperature of 1050 to 1150 ° C. After reheating within the above-mentioned temperature range, hot rolling is performed to obtain a hot rolled sheet having a thickness of 2.0 to 3.0 mm. If the temperature is too low, the hot rolled sheet will not work well. If the temperature is too high, the hot rolled sheet will be coarsened and the magnetism will be adversely affected. Since the content of carbon black in the above composition is low, it is preferable that the slab temperature is in the range of 1050 to 1100 ° C, which is lower than the normal condition in terms of refinement of the hot-rolled structure, and the recrystallization and growth It is preferable to set the cumulative rolling reduction in the initial high-temperature region of the hot-rolling to 30% or more so as to be effective in miniaturizing the hot-rolled structure.

The hot-rolled hot-rolled sheet is subjected to hot-rolled sheet annealing, pickling and cold rolling to adjust the final thickness to 0.2 to 0.35 mm. A detailed description thereof will be omitted because a normal technician can appropriately select and apply the method.

The ordinary cold-rolled cold-rolled sheet undergoes recrystallization annealing, decarburization annealing and nitriding annealing in a mixed gas atmosphere of ammonia, hydrogen and nitrogen. In an embodiment of the present invention, it is possible to reduce the content of carbon black during the annealing process and to perform only recrystallization annealing and nitriding annealing by omitting decarburization annealing.

The cold-rolled sheet can be subjected to recrystallization annealing at a temperature of 800 to 950 占 폚 within a relatively short period of time of about 1 minute or less, and the recrystallization time is set to 30 seconds or less.

Thereafter, after the recrystallization annealing is completed, nitriding annealing is performed in a temperature range of about 800 to 900 占 폚 at a relatively high temperature. In the case of decarburization annealing after decarburization annealing rather than simultaneous decarburization annealing and nitriding annealing, recrystallization is completed at a relatively low temperature of 800 to 850 占 폚 to obtain a desired grain size. However, if the nitriding treatment is performed again in this temperature range, the crystal grains will grow again, and uneven grain distribution can be generated in the steel sheet. Therefore, a precipitate such as Si ₃ N ₄ or (Si, Mn) N is formed in the steel sheet by performing steep annealing at a temperature of usually about 770 ° C. Such a stone is thermally unstable and easily decomposed, (Al, Si) N or the like, it is necessary to maintain it at a high temperature for a long period of time.

However, according to the embodiment of the present invention, the recrystallization annealing is performed at a relatively high temperature of 800 to 950 DEG C, so that the annealing temperature can be increased to 800 DEG C or more, and a thermal stability similar to that of simultaneous decarburization annealing and nitriding annealing (Al, Si) N or the like is formed, the additional high-temperature heat treatment process becomes unnecessary.

The annealed steel sheet subjected to the recrystallization annealing and nitriding annealing is coated with an annealing separator containing MgO as a basic component and wound thereon and subjected to high temperature annealing for a long time to obtain a steel sheet having a {110} < 001 & Steel sheet. In the high-temperature annealing process, the first recrystallized steel sheet is subjected to a temperature raising process for secondary recrystallization and then a secondary recrystallization process for removing impurities from the steel.

At this time, in order to increase the productivity of the high-temperature annealing, it is possible to carry out the high-temperature annealing at a temperature increase rate of up to 300 ° C / h by raising the heating rate to 15 ° C / h, which is a normal operating condition. The excellent magnetism can be obtained even at a high temperature increase rate.

When producing a grain-oriented electrical steel sheet according to such a manufacturing method, the final product may contain less than 10 ppm of carbon (C).

Hereinafter, the present invention will be described in more detail with reference to examples.

(Ni) content in a basic composition of 3.2% by weight Si, 0.028% by weight of Al, 0.028% by weight of Mn, 0.1% by weight of Mn, 0.005% by weight of C and 0.005% The slab is reheated at a temperature of 1100 占 폚 and hot rolled at a temperature of 1000 占 폚 or higher in a high temperature region at a cumulative rolling reduction of 30% or more, then cracked at a temperature of 1100 占 폚 for 180 seconds, After pickling, cold rolling was carried out.

The cold-rolled cold-rolled sheet was subjected to recrystallization annealing in a mixed gas atmosphere of hydrogen and nitrogen at a temperature of 840 ° C without omitting the decarburization annealing process, and further nitrided in a mixed gas atmosphere of hydrogen, nitrogen and ammonia at a temperature of 860 ° C for 30 seconds Annealing was performed. Thereafter, the high-temperature annealing was carried out at a heating rate of 100 ° C / h, and then the magnetic flux density value was measured and shown in Table 1.

Ni content
(%) Primary Recrystallization Size
(탆) (411) / (111) <112> S. Deviation B8
(Tesla) 0 27.7 0.65 13.5 1.80 0.01 27.5 1.2 12.8 1.85 0.1 25.9 1.5 12.1 1.89 0.2 26.4 1.3 13.5 1.85 0.2 24.7 1.5 11.6 1.89 0.5 24.7 1.8 11.9 1.90 0.5 25.5 1.9 11.5 1.91 One 23.6 2.2 11.5 1.75 2 21.1 2.5 11.1 1.61

(% By weight) of Si: 3.2%, acid soluble Al: 0.028%, Mn: 0.1%, N: 0.005%, C: 0.002%, Ni: 0.001 to 1.0%, S: 0.005% And the remainder Fe was inevitably impregnated into the slab, and then the slab was reheated at a temperature of 1100 DEG C, and then the cumulative reduction ratio in the high temperature region of 1000 DEG C or more was maintained at 30% or more, , And then cracked at a temperature of 1100 DEG C for 180 seconds, cooled, pickled, and then cold-rolled.

The cold-rolled steel sheet was subjected to recrystallization annealing in a mixed gas atmosphere of hydrogen and nitrogen at a temperature of 880 ° C, omitting the decarburization process, and then subjected to nitriding annealing in a mixed gas atmosphere of hydrogen, nitrogen and ammonia at a temperature of 860 ° C for 30 seconds Respectively. Thereafter, the high-temperature annealing was carried out at a heating rate of 300 ° C / h, and the magnetic flux density values were measured.

Ni content
(%) Primary Recrystallization Size
(탆) (411) / (111) <112> S. Deviation B8
(Tesla) 0 35.5 0.78 14.1 1.65 0.01 35.1 1.0 13.1 1.79 0.1 35.2 1.2 12.8 1.85 0.2 33.8 1.5 12.5 1.89 0.2 34.1 1.8 12.9 1.88 0.5 33.8 2.1 11.9 1.90 0.5 33.3 2.5 11.5 1.91 One 32.9 2.3 11.1 1.87 2 29.9 2.1 11.4 1.55

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the exemplary embodiments or constructions. It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention. will be.

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 (8)

0.005% or less of S, 0.005% or less of C, 0.005% or less of C, 0.005% or less of C, 0.005% or less of Al, 0.01 to 0.04% : 0.001 to 1.0%, and reheating the slab comprising the remainder Fe and other unavoidable impurities;
Hot rolling the reheated slab at a cumulative rolling reduction of 30% or more in a temperature range of 1,050 to 1,150 占 폚;
Cold-rolling the hot-rolled steel sheet;
Subjecting the cold-rolled cold-rolled sheet to recrystallization annealing and nitriding annealing; And
Subjecting the recrystallized annealed and nitrided annealed steel sheet to high-temperature annealing
Wherein the method comprises the steps of: The method of claim 1,
Further comprising a step of annealing the hot-rolled steel sheet to a hot-rolled steel sheet. The method of claim 1,
Wherein the high-temperature annealing is performed at a heating rate of 100 to 300 占 폚 / h at a starting temperature of 1,150 占 폚. 4. The method of claim 3,
Wherein the recrystallization annealing is performed at 840 to 880 캜 within 1 minute, and the nitriding annealing is performed at 860 to 900 캜. 5. The method according to any one of claims 1 to 4,
Wherein the size of recrystallized grains after recrystallization annealing and nitriding annealing is 20 to 35 占 퐉. 5. The method according to any one of claims 1 to 4,
Wherein the ratio of the number of crystal grains in the (411) <001> orientation to the crystal grains in the (111) <112> orientation after the recrystallization annealing and nitriding annealing is 1.0 or more. The method of claim 6,
Wherein a standard deviation value of a grain size after recrystallization annealing and nitriding annealing is 12.0 or less. The steel sheet according to any one of claims 1 to 3, wherein the steel sheet has a weight percent (wt%) of 2.0 to 4.0% Si, 0.01 to 0.04% of an Al-soluble Al, 0.20% or less of Mn, 0.006% or less of N, To 1.0%, balance Fe and other unavoidable impurities.

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