JPH08232020A - Production of grain oriented silicon steel sheet - Google Patents

Abstract

PURPOSE: To inexpensively produce a silicon steel sheet excellent in magnetic properties by subjecting a steel of specific composition to cold rolling at specific rolling rate and to annealing, regulating the total nitrogen content to specific ppm, applying a separation agent at annealing to the resulting sheet, and then finish-annealing it. CONSTITUTION: A steel, having a composition consisting of, by weight ratio, 0.001-0.09% C, 2-4.5% Si, 0.01-0.08% acid soluble Al, 0.0001-0.004% N, 0.008-0.06%, independently or in total, of S and/or Se, 0.01-1% Cu, 0.01-0.5% Mn, small amounts of one or more elements among Bi, P, Sn, Sb, Pb, B, V, Nb, and Zr, and the balance Fe with inevitable impurities, is used. A cold rolled sheet of silicon steel, prepared by cold-rolling the steel at 75-95% cold rolling rate before primary recrystallization annealing, is annealed at 800-1000 deg.C for 1-300sec, and then the total nitrogen content is regulated to 50-1000ppm. After the application of a separation agent at annealing, finish-annealing is done. By this method, magnetic flux density can be increased.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a grain-oriented electrical steel sheet.

[0002]

2. Description of the Related Art A precipitate or solute atom that suppresses grain growth is called an inhibitor. AlN is used as a main inhibitor, and the cold rolling rate before primary recrystallization is 75% or more.
%, The grain size of the grain-oriented electrical steel sheet manufactured by the method is, for example, Japanese Examined Patent Publication No. 57-9419, 62-54846, 59-
48935, 60-48862, 63-11406, 6
The production method disclosed in each of the publications, for example, 3-11407 (hereinafter referred to as A
Called Hou) and Japanese Patent Publications 61-60896, 62-4528
The manufacturing method disclosed in Japanese Patent No. 5 (hereinafter referred to as Method B) is known.

In the method A, finely dispersed AlN and MnS are mainly used as inhibitors necessary for secondary recrystallized grain growth. Therefore, after these precipitation phases are completely melted at the time of heating the slab, fine precipitation is performed in the hot rolling and hot rolled sheet annealing steps. Therefore, it is necessary to set the slab heating temperature to a high temperature of about 1400 ° C. Due to the presence of such finely dispersed precipitates, the primary recrystallized grain size is as small as about 8 μm.

On the other hand, in method B, AlN is mainly used as an inhibitor. The main part of this AlN is formed by substantially uniformly precipitating nitrides of the steel sheet surface phase formed by nitriding after primary recrystallization as AlN in the plate thickness direction in the secondary recrystallization annealing process. In the method B, the slab heating temperature is as low as about 1150 ° C. At this stage, AlN has already precipitated, so finely dispersed A during primary recrystallization annealing.
Almost no 1N or MnS precipitates are present. Therefore, the crystal grain size after primary recrystallization annealing at a primary recrystallization annealing temperature of about 840 ° C., which is almost the same as in method A, is as large as about 24 μm.

Therefore, in method B, since the inhibitor strength is weak after the primary recrystallization annealing, the nitriding treatment is performed after the primary recrystallization annealing to strengthen the inhibitor in the secondary recrystallization annealing process, and the amount of nitrogen is set to about 200 ppm.

The magnetic flux density of the final product is slightly higher in the method A than in the method B, but it is necessary to heat the slab at an extremely high temperature, and since S content is about 0.03%, there is a problem of ear cracking during hot rolling. It has the drawback of frequent occurrence. Method B does not require such high temperature heating, and since S is low, ear cracking does not occur. However, it has a drawback that the magnetic flux density is slightly lower than that of the method A.

[0007]

In the present invention, even when the slab heating temperature is as low as about 1000 ° C., it is preferable that N, which is a base for forming a nitride so that the nitride substantially forms a solid solution in the slab heating stage, is 0. After the content of 0.002% by weight or less, the grain size at the time of primary recrystallization is easily controlled by making the nitrided portion almost absent, and the secondary recrystallization process is performed by performing the primary recrystallization annealing and nitriding treatment. In order to secure the strength of the inhibitor by forming a fine and homogeneously dispersed nitride, a stable low-cost manufacturing of a product having a high magnetic flux density equal to or higher than that of the method A, while performing low-temperature slab heating as in the method B, is possible. It provides a method.

[0008]

The means of the present invention are as follows. C: 0.001 to 0.090% by weight, Si:
2.0-4.5% by weight, acid-soluble Al: 0.010
0.080% by weight, N: 0.0001 to 0.0040% by weight, preferably 0.002% by weight or less, S or Se
Sum: 0.0080 to 0.060% by weight, Cu: 0.0
1-1% by weight, Mn: 0.01-0.5% by weight, and B
i: 0.005-0.15% by weight, P: 0.001-
0.15 wt%, Sn: 0.001-0.3 wt%, S
b: 0.001 to 0.15% by weight, Pb: 0.001 to
0.15% by weight, B: 0.0010 to 0.1% by weight,
V: 0.01 to 0.10% by weight, Nb: 0.001 to
0.10% by weight, Zr: 0.001 to 0.10% by weight, one or more kinds are contained, and the cold rolling rate before primary recrystallization annealing containing the balance Fe and unavoidable impurities is 75% or more. Magnetic steel cold rolled sheet with 95% or less is 800 ° C or more and 100
In the method for producing a grain-oriented electrical steel sheet, which is subjected to finish annealing by applying a post-annealing agent after adjusting so that the total nitrogen amount is within a range of 50 ppm to 1000 ppm after heating at a temperature of 0 ° C. or less for 1 second to 300 seconds, The purpose is to control so that the average crystal grain size after the primary recrystallization annealing falls within the range shown in FIG.

[0009]

The present invention will be described in detail below. The inventor studied the conditions for preferential expression of (110) [001] secondary recrystallized grains of grain-oriented electrical steel sheet and obtained the following conclusions.
In general, the inhibitor suppresses the crystal grain growth in the primary recrystallization annealing process to reduce the primary recrystallization grain size, and suppresses the growth of the matrix crystal grains in the secondary recrystallization annealing process to affect the secondary recrystallization start temperature. And influence the selection of the secondary recrystallization orientation to be developed.

For the purpose of making it easier to understand the role of the inhibitor that acts from the formation of the primary recrystallization structure to the completion of the secondary recrystallization, the inhibitor which should also determine the primary recrystallization grain size is referred to as a primary inhibitor. The primary inhibitor is formed in a process from melting to primary recrystallization, and should be called an innate inhibitor in contrast to the B method in which the inhibitor is added by performing nitriding treatment after primary recrystallization annealing.

The higher the primary inhibitor strength, the smaller the primary recrystallized grain size. An inhibitor from the completion of primary recrystallization to the appearance of secondary recrystallization is called a secondary inhibitor.

The primary purpose of the nitriding process of Method B is to provide a secondary inhibitor. This addition of inhibitor by nitriding should be called acquired inhibitor. Since the driving force of the secondary recrystallized grains is grain boundary energy, the smaller the driving force, that is, the larger the matrix grain size, the higher the secondary recrystallization temperature becomes. If the crystal grain size is the same, the higher the secondary inhibitor strength, the higher the secondary recrystallization temperature.

The secondary recrystallization temperature cannot be determined only by the strength of the secondary inhibitor, but here, considering the crystal grain size,
Weak secondary inhibitor when secondary recrystallization temperature is low,
The higher the secondary recrystallization temperature is, the stronger the secondary inhibitor is.

The inhibitor strength during the process in which the secondary recrystallized grains are selectively grown, that is, the inhibitor strength which is deeply involved in the preferential growth of the already developed secondary recrystallized grains is called a tertiary inhibitor. The stronger the tertiary inhibitor strength, the larger the difference in grain boundary migration between the general grain boundary and the corresponding grain boundary, and the secondary recrystallized grains grow preferentially.

The inhibitor strength at the start of secondary recrystallization can be said to be the secondary inhibitor strength by emphasizing the initiation of secondary recrystallization, and by emphasizing the fact that secondary recrystallized grains are being generated and growing. It can be said to be a tertiary inhibitor. In the method B in which the nitriding treatment is performed after the primary recrystallization annealing, the inhibitor strength is significantly different between the completion of the primary recrystallization and the start of the secondary recrystallization annealing, but in the case of the method A, the primary inhibitor strength and the initiation of the secondary recrystallization annealing are performed. Is almost the same as the secondary inhibitor strength of.

As described above, the primary recrystallized grain size is almost determined by the strength of the primary inhibitor. In the method A, for example, when only MnS is used as an inhibitor, the thickness is 18 μm, when only AlN is 14 μm, and when the normal method A using AlN and MnS together is 8 μm. Further, the same AlN is used in the case of the B method in which the slab heating temperature is as low as 1150 ° C. However, the primary recrystallized grain size is as large as about 24 μm because the primary inhibitor is weak due to the large precipitation size of AlN. That is, it can be said that the particle size differs by about 10 μm only by the difference in the precipitation dispersion state of AlN.

The slab heating temperature of the steel of the present invention is as low as that of the B method, but since the nitrogen content is 0.004%, preferably 0.002% or less, precipitates consisting of AlN and other nitrides are precipitated in the slab heating stage. If so, it is extremely small. Therefore, there is almost no effect of refining the primary recrystallized grain size by this precipitate. However, MnS (Se), CuS (S
e), inhibitors such as Bi and P, Sn, Sb, P
Since it contains one or more of b and B, the primary recrystallized grain size is larger than that of the A method and is the same or smaller than that of the B method.

In the presence of the inhibitor, secondary recrystallization annealing causes slight grain growth due to grain boundary migration.
When a certain temperature (critical secondary recrystallization temperature Tcr) is reached, there is a large difference in the grain boundary moving speed between the general grain boundary and the corresponding grain boundary. In this state, the crystal orientation with the highest probability of contact with the corresponding grain boundary eats the surrounding crystal grains and becomes large, and the size effect (dimensional advantage) is obtained to start abnormal growth. That is, it is the expression of secondary recrystallization.

Corresponding grains having a high frequency of occurrence that are involved in secondary recrystallization of grain-oriented electrical steel sheets exist in the corresponding grain boundaries, which easily move during the secondary recrystallization grain growth process, from Σ5 corresponding grain boundaries to Σ33 corresponding grain boundaries. There are three types of boundaries, Σ5, Σ7, and Σ9. Among them, the Σ7 grain boundary is a unidirectional electrical steel sheet, and its existence frequency is low. Therefore, the Σ5 grain boundary and the Σ9 grain boundary may be considered.

In the primary recrystallized sheet of the present invention in which the cold rolling rate is 75% or more and 95% or less, the (110) [001] oriented grains have the highest probability of forming Σ9 corresponding grain boundaries as compared with other orientations. Further, there is a high probability that a Σ5-corresponding grain boundary is formed in an orientation deviating from the ideal (110) [001] direction.

The Σ5-corresponding grain boundary is slightly different in the temperature region where the Σ9-corresponding grain boundary easily moves and the inhibitor strength range. When the Σ5 grain boundary and the Σ9 grain boundary coexist, Σ5
If the grain boundary has weaker inhibitor strength, or if the inhibitor strength is the same, it becomes easier to move preferentially at lower temperatures.

Therefore, in order to preferentially grow the secondary recrystallized grains in the (110) [001] orientation with high integration, Σ5
The temperature range where the grain boundaries preferentially move and Σ9 grain boundaries are also Σ
It is necessary to strengthen the secondary inhibitor so that the Σ9 grain boundary becomes easier to move in the temperature range where the 5 grain boundaries also move easily.

In method A, since the primary recrystallization grain size is small, the secondary inhibitor is weak and secondary recrystallization occurs at low temperature. In the A method, Al is in the range of 0.022 to 0.030%, but when Al is low in that range, the primary recrystallized grain size becomes small by 1 to 2 μm, and Al is oxidized in the secondary recrystallization annealing process. As a result, the amount of Al near the surface of the steel sheet is further reduced, and the inhibitor strength of this portion is weakened.

Therefore, secondary recrystallization develops from this portion, but the temperature at which this secondary recrystallization develops is a low temperature of 925 ° C. or lower, and the Σ5 grain boundary moves preferentially, so the secondary recrystallization orientation that develops is The azimuth is 10 ° or more away from the ideal Goss azimuth.

On the other hand, when Al is as high as 0.033% or more, the primary particle size becomes large and the driving force decreases, and because the Al concentration itself is high, AlN is immediately formed and the inhibitor strength does not decrease. Therefore, the secondary inhibitor becomes relatively strong, and the occurrence of secondary recrystallization at low temperature can be prevented. Therefore, it is possible to prevent the occurrence of secondary recrystallization having a bad orientation due to the preferential grain boundary movement of the Σ5 grain boundary.

However, the secondary recrystallization temperature is 1100 ° C.
At the above high temperature, Al is rapidly oxidized, the tertiary inhibitor strength is rapidly reduced, and selective grain boundary migration is difficult to occur, and secondary recrystallization does not occur, resulting in a fine grain structure.

Therefore, in order to develop the secondary recrystallization having a high degree of integration of the (110) [001] orientation by the method A, it is necessary to prevent the secondary recrystallization from appearing at a low temperature and to increase the tertiary inhibitor strength at a high temperature. In order to prevent a sharp decrease in particle size and the generation of fine particles, it is necessary to control the Al content within an extremely narrow range.

On the other hand, in the method B, the Al content is low and the Al content near the surface phase is
However, secondary recrystallization does not occur at a low temperature of 925 ° C. or below where the Σ5 grain boundary tends to move preferentially due to the large grain size, even if de-Al occurs because it is nitrided from the surface phase. Since AlN is immediately formed, it is possible to prevent the decrease of the inhibitor near the surface phase, and it is possible to prevent the secondary recrystallization from occurring at a low temperature of 925 ° C or lower. However, since the primary inhibitor strength is weak in the B method, the primary recrystallized grain size is likely to fluctuate due to variations in finish hot rolling start temperature, solid solution Al, primary recrystallization annealing temperature, and the like.

When the primary recrystallization grain size is too large or the nitriding amount is too large, the secondary recrystallization temperature becomes 1100 ° C. or higher, the oxidation rate of Al remarkably increases, and the tertiary inhibitor strength sharply decreases. The selective moving speed of the grain boundary becomes relatively slow, and the degree of integration of the secondary recrystallization in the (110) [001] orientation decreases.

By the way, in method A, secondary recrystallization occurs at a lower temperature than method B, but the secondary recrystallization orientation (11
0) The degree of [001] orientation integration is equal to or higher than that of the B method. The reason for this is that in method A, since finely dispersed MnS exists in addition to finely dispersed AlN, the tertiary inhibitor strength is equal to or higher than that in method B as compared with method B in which the inhibitor is mainly composed of only AlN. Because of.

In method B, nitriding is performed after primary recrystallization, and since the primary recrystallization grain size is large, almost no grain growth is observed until secondary recrystallization occurs, and the secondary recrystallization starting temperature is higher than in method A. . That is, the strength of the secondary inhibitor is stronger than that of Method A. However, the degree of orientation integration of the secondary recrystallized grains that appear is equal to or slightly inferior to that of the method A. This is because the tertiary inhibitor is equal to or slightly weaker than Method A.

In the case of the steel of the present invention, only sulfides are precipitated in the hot rolling stage, and the nitriding treatment is performed after the primary recrystallization annealing.
By forming a nitride with these sulfides as nuclei, the strength of the primary inhibitor and the secondary inhibitor becomes an intermediate strength between methods A and B, and the strength of the tertiary inhibitor becomes equal to or higher than that of method A.

In other words, before the primary recrystallization annealing, almost no nitride exists, and only the sulfides and other additives are present, so the primary inhibitor strength is weaker than the A method in which sulfides and nitrides are finely dispersed, but MnS. Since it contains (Se), CuS (Se), and Bi, and P, Sn, Pb, B, and Sb are added if necessary, these effects are stronger than the B method.

Therefore, the crystal grain size after primary recrystallization of the material of the present invention is larger than the A method and smaller than or equal to the B method. The secondary recrystallization starting temperature in the case of the method of the present invention is equal to or slightly lower than that in the method B, and higher than that in the method A. The reason for this is that the particle size is larger than in method A.

The secondary recrystallization (11
0) [001] orientation integration is slightly better than either method A or B. The reason is that the tertiary inhibitor is stronger than either method A or B.

The reason for limiting the other conditions will be described below. When the treatment according to the method of the present invention is performed, secondary recrystallization having a high magnetic flux density can be obtained even if C exceeds 0.090%, but if C is higher than this, the decarburization time of the primary recrystallization annealing becomes long and it is not economical . The lower limit of C is set to 0.001% because even if C is less than this, it does not affect the property improvement, and it is not economical to reduce C below this.

As the content of Si increases, the specific resistance increases and the eddy current loss of the product decreases. Therefore, the more Si, the better. The reason why Si is limited to 2.0% or more is that the lower limit is 2.0% because eddy current loss is large and it is not preferable below this range. However, Si becomes more likely to crack in the cold rolling process as the added amount increases. If the Si content is 4.5% or more, the cold rolling requires a special device and the purpose of the present invention is to economically manufacture the steel.
It was set to 5%.

Al forms (Al, Si) N and acts as an inhibitor, but the effect is not exhibited unless the content of acid-soluble Al is 0.010% or more, so the lower limit is 0.010.
%. The upper limit of 0.080% is A
This is because if l is present, it will not work effectively as an inhibitor.

V forms VN and acts as an inhibitor, but the effect is not exhibited unless it is 0.01% or more, so the lower limit was made 0.01%. The upper limit is set to 0.10% because if it exceeds V, it will not work effectively as an inhibitor.

Nb forms Nb nitride and acts as an inhibitor, but the effect is not exhibited unless it is 0.001% or more, so the lower limit was made 0.001%. The upper limit is 0.10
The reason why the percentage is set is that if more Nb is present, it will not work effectively as an inhibitor.

Zr forms a Zr nitride and acts as an inhibitor, but the effect is not exhibited unless it is 0.001% or more, so the lower limit was made 0.001%. The upper limit is 0.10
% Is because if more Zr is present, it will not work effectively as an inhibitor.

N forms nitrides and acts as an inhibitor, but if it is 0.0040% or less, preferably 0.002% or less at the stage of slab, it is nitrided until primary recrystallization annealing regardless of hot rolling conditions. Formation can be prevented. Then, by nitriding, it is possible to form a nitride although it is finely dispersed uniformly. When N exceeds 0.004%, a nitride is formed before the primary recrystallization, but the number of this nitride is small and the size is large. In many cases, it does not disperse, and it does not work effectively in developing secondary recrystallized grains with excellent orientation. Therefore, the upper limit of N is set to 0.0040%, preferably 0.002%.

The lower limit of 0.0001% is that if the amount of nitrogen is lowered so far, no nitride is formed in the hot rolling process, and nitriding after the primary recrystallization annealing makes the strong nitride uniform. It is possible to disperse, but if you lower it further,
The effect of uniformly finely dispersing the nitride after the primary recrystallization annealing does not change, so the lower limit was made 0.0001%.

The following elements have the function of strengthening the primary inhibitor, but are added mainly for the purpose of strengthening the tertiary inhibitor. Bi has a function of strengthening the tertiary inhibitor, but the effect is small at 0.0050% or less, so the lower limit was made 0.005%. Although Bi is effective even if it is 0.15% or more, it is not economical to add more than Bi, so the upper limit was made 0.15%.

S or Se alone or the total thereof is limited to the range of 0.0080 to 0.060% because S or Se alone or the total thereof is 0.0080% in the raw material component of the present invention. When the ratio is less than 3, the tertiary inhibitor is weak and the number of secondary recrystallized grains deviating from (110) [001] increases.

The larger the content of Se and S, the stronger the effect of strengthening the tertiary inhibitor, and the higher the magnetic flux density. However, if they are 0.060% or more, ear cracks are likely to occur during hot rolling, so the upper limit is 0.060%. And

Cu has the function of forming a precipitate with S and Se or strengthening the tertiary inhibitor by itself.
If it is less than 0.01%, the effect is small, so the lower limit is 0.0
It was set to 1%. Although the addition of 1% or more has the effect of strengthening the tertiary inhibitor, it is not economical to add more than that, so the upper limit was made 1%.

Mn has a function of forming a precipitate with S and Se to strengthen the tertiary inhibitor, but its effect is small at 0.01% or less, so the lower limit was made 0.01%. 0.
Addition of 5% or more has the effect of strengthening the tertiary inhibitor, but it is not economical to add more than that, so the upper limit is set to 0.
It was set to 5%.

P has a function of strengthening the tertiary inhibitor, but the effect is small at 0.001% or less, so the lower limit was made 0.001%. P is effective even if it is 0.15% or more, but it is not economical to add more than P, so the upper limit was made 0.15%.

Sn has a function of strengthening the tertiary inhibitor, but the effect is small at 0.001% or less, so the lower limit was made 0.001%. Although Sn is effective even if it is 0.3% or more, it is not economical to add more than this, so the upper limit was made 0.3%.

Sb has a function of strengthening the tertiary inhibitor, but the effect is small at 0.001% or less, so the lower limit was made 0.001%. Although Sb is effective even if it is 0.15% or more, it is not economical to add more than Sb, so the upper limit was made 0.15%.

Pb has a function of strengthening the tertiary inhibitor, but the effect is small at 0.001% or less, so the lower limit was made 0.001%. Pb is effective even if it is 0.15% or more, but it is not economical to add more than this, so the upper limit was made 0.15%.

B has a function of strengthening the tertiary inhibitor, but the effect is small at 0.0010% or less, so the lower limit was made 0.0010%. B is effective even if it is 0.1% or more, but it is not economical to add more than 0.1%, so the upper limit was made 0.1%.

The cold rolling rate before primary recrystallization is set to 75% or more because the cold rolling rate lower than this is the grain boundary corresponding to Σ 9 for the preferential growth of (110) [001] secondary recrystallized grains. 75 is less likely to form
% Or less. The upper limit is set to 95% or less because if the cold rolling rate is further increased, the amount of the (110) [001] orientation, which is the core, becomes small, the secondary recrystallized grain size becomes remarkably large, and iron loss deteriorates. The upper limit was set to 95%.

The primary recrystallization annealing temperature is set to 800 ° C. or higher, because high magnetic flux density may not be obtained when annealing is performed at a temperature lower than 800 ° C. Although the annealing temperature is set to 1000 ° C. or lower, a high magnetic flux density can be obtained even if annealing is performed at a temperature higher than this, but it is set to 1000 ° C. or lower because it is thermally uneconomical.

The reason why the heating time is set to 1 second or longer is that if the heating time is shorter than this, the magnetic flux density tends to vary.
The reason for setting it to 0 seconds or less is that it is not economical because the magnetic flux density is not improved even if it is heated for a longer time. If necessary, the amount of nitrogen after primary recrystallization annealing is set to 50 ppm or more because the tertiary inhibitor is weak and a high magnetic flux density cannot be obtained below this amount. This is because the magnetic flux density can be obtained, but it is not economical to perform the nitriding treatment in order to increase the nitrogen content further. The crystal grain size after the primary recrystallization annealing is limited to the range of FIG. 1 because it is difficult to stably obtain a high magnetic flux density outside this range.

[0057]

EXAMPLES C: 0.002%, Si: 3.25%, M
n: 0.074%, P: 0.099%, Al: 0.03
6%, S: 0.0090%, Sn: 0.051%, C
u: 0.15%, Bi: 0.086%, N: 0.001
%, Sb: 0.062% as a main component of the slab 105
After heating at a temperature of 0 ° C. for 2 hours, rough rolling and finish rolling were performed to obtain a hot rolled sheet having a thickness of 2.3 mm. The steel plate is 900 ℃ 120
Second hot-rolled sheet annealing followed by cold rolling to a thickness of 0.30
mm. In this case, the plate thickness during cold rolling is 1.6 mm, 1.2
mm, 0.8mm, 0.6mm, 0.4mm at 250 ℃
Pass aging rolling was performed under the condition of holding for 20 minutes.

Then, at a temperature of 900 ° C., a dew point of 69 ° C. and 75
After heating at% H ₂ -N ₂ atmosphere, the amount of nitrogen carried out nitriding treatment was 104ppm and 130 ppm. At this time, the crystal grain size after the primary recrystallization annealing was 20 μm. Then by weight M
To 100 parts of gO + 5 parts of TiO ₂ , Na ₂ B ₄ O
Apply the annealing separator mixed with ₇ parts in a ratio of 0.3 parts to 95
1200 at a temperature rising rate of 15 ° C./hr in an atmosphere of% N ₂ —H _2.
After heating to 0 ° C., it was heated in a 100% H ₂ atmosphere for 20 hours and then cooled. Then, strain relief annealing is performed to measure the magnetic flux density, and the value is shown in Table 1.

For the sake of comparison, process treatments were also carried out for method A and method B. As method A, C: 0.078%, Si:
3.25%, Mn: 0.075%, P: 0.01%,
S: 0.025%, Al: 0.030%, N: 0.00
A slab containing 83%, Cu: 0.07%, and Sn: 0.12% as main components was heated at 1400 ° C for 2 hours, immediately rolled to a thickness of 2.3 mm, and wound at 550 ° C. Then 112
After heating to 0 ° C. for 100 seconds, it was heated at 930 ° C. for about 120 seconds and then cooled with water.

Next, cold rolling was performed under the same conditions as the material of the present invention,
It was heated at 830 ° C. for 120 seconds in the same atmosphere as the material of the present invention.
The crystal grain size after the primary recrystallization annealing was 8 μm. Then, the same annealing separator as that of the present invention is applied, and 25% N ₂ -H ₂ is applied.
After heating to 1200 ° C. at a temperature rising rate of 15 ° C./hr in the above atmosphere, heating was performed in a 100% H ₂ atmosphere for 20 hours and then cooled. Then, strain relief annealing is performed and the magnetic flux density is measured.
Shown in

As the B method, C: 0.055%, Si:
3.25%, Mn: 0.100%, P: 0.025%,
S: 0.007%, Al: 0.030%, N: 0.00
77%, Cu: 0.07%, Sn: 0.05%, Cr:
A slab containing 0.12% as a main component was heated at 1150 ° C. for 2 hours, immediately rolled to a thickness of 2.3 mm, and wound at 550 ° C. Then, it was heated to 1120 ° C. for 100 seconds, heated at 930 ° C. for about 120 seconds, and then cooled with water.

Next, cold rolling is performed under the same conditions as the material of the present invention,
After heating at 830 ° C for 120 seconds in the same atmosphere as the material of the present invention, 77
Nitrogen treatment was performed at 0 ° C. for 36 seconds to adjust the amount of nitrogen to 200 ppm. The crystal grain size after the primary recrystallization was 24 μm.

Then, the same annealing separator as that of the present invention was applied, heated to 1200 ° C. in a 50% N ₂ —H ₂ atmosphere at a heating rate of 15 ° C./hr, and then heated in a 100% H ₂ atmosphere for 20 hours. Cooled. Then, strain relief annealing is performed and the magnetic flux density is measured and shown in Table 1. As shown in Table 1, the magnetic steel sheet produced according to the present invention has a remarkably high magnetic flux density even though the hot-rolled sheet annealing is omitted. As shown in Table 1, the material of the present invention had good magnetic characteristics equivalent to or better than those of the comparative material.

[0064]

[Table 1]

[0065]

According to the present invention, an electromagnetic steel sheet having excellent magnetic properties can be manufactured at low cost.

[Brief description of drawings]

FIG. 1 is a chart showing the relationship between the crystal grain size and the primary recrystallization temperature after the primary recrystallization annealing of the methods A, B and the method of the present invention.

Claims (2)

[Claims] 1. C: 0.001 to 0.090% by weight, Si: 2.0 to 4.5%, acid-soluble Al: 0.010 to 0.080%, N: 0.0001 to 0. 0.0040%, S or Se alone or the sum thereof: 0.0080 to
0.060%, Cu: 0.01 to 1%, Mn: 0.01 to 0.5%, and Bi: 0.005 to 0.15%, P: 0.001 to 0.15%, Sn: 0.001-0.3%, Sb: 0.001-0.15%, Pb: 0.001-0.15%, B: 0.0010-0.1%, V: 0.01-0. 1% or more of 10%, Nb: 0.001 to 0.10%, Zr: 0.001 to 0.10%, cold rolling rate before primary recrystallization annealing containing balance Fe and unavoidable impurities After annealing the electromagnetic steel cold-rolled sheet with a temperature of 75% or more and 95% or less at a temperature of 800 ° C. or more and 1000 ° C. or less for 1 second or more and 300 seconds or less, a total amount of nitrogen is adjusted to 50 ppm or more and 1000 ppm or less, and a post-annealing separator is used. A method for manufacturing a grain-oriented electrical steel sheet, which comprises applying and finish annealing. 2. The average crystal grain size after primary recrystallization annealing is shown in FIG.
Point A (800 ° C, 18 μm), point B (800 ° C,
14 μm), C point (1000 ° C., 14 μm), D point (1
The method for producing a grain-oriented electrical steel sheet according to claim 1, wherein the grain size is in a range surrounded by 000 ° C. and 26 μm).