JP2001040416A - Manufacture of grain oriented silicon steel sheet with high goss integration degree - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a grain oriented silicon steel sheet having high Goss integration degree and superior iron loss, on the assumption that a low temperature slab heating - nitriding process is used. SOLUTION: The grain oriented silicon steel sheet can be manufactured by subjecting a silicon steel slab, having a composition consisting of, by weight, 0.02-0.10% C, 2.5-4.0% Si, 0.05-0.45% Mn, <=0.015% S and/or Se, 0.020-0.035% acid-soluble Al, 0.0035-0.012% N, and the balance Fe with inevitable impurities, to heating to <=1280 deg.C and to hot rolling, annealing the resultant hot rolled plate, applying cold rolling at >=80% draft, and then subjecting the resultant sheet to decarburizing annealing, nitriding treatment, and finish annealing. In this case, the average grain size of non-transformed ferritic phases in the annealed hot rolled plate is controlled to 28-85 μm (preferably 35-65 μm). Further, according to Si content (%), C content (%) is regulated to a value within the range satisfying 0.023×Si(%)-0.032-<=C(%)<=0.025×Si(%)-0.010.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a unidirectional magnetic steel sheet having a crystal orientation (Goss orientation) in one direction, which is used for an iron core material of electric equipment such as a transformer.

[0002]

2. Description of the Related Art A grain-oriented electrical steel sheet has a steel sheet surface of $ 11.
In the 0 ° plane, the rolling direction has a <100> axis,
It is composed of crystal grains having a Goss orientation (representing the {110} <001> orientation in Miller index), and is used as a soft magnetic material in cores of transformers and generators. This steel plate
Magnetization and iron loss properties must be good as magnetic properties, but good or bad magnetizing properties are determined in a constant applied magnetic field.
Determined by the level of magnetic flux density induced in the iron core (steel plate),
An electromagnetic steel sheet having a high magnetic flux density has an advantage that the iron core can be downsized. High magnetic flux density can be achieved by highly aligning the crystal grain orientation in the steel sheet to {110} <001>. The magnetic flux density is usually 800 A /
It is indicated by the value B8 at a magnetic field strength of m.

On the other hand, iron loss is power loss consumed as heat energy when a predetermined alternating magnetic field is applied to an iron core. The quality of the iron loss is determined by the magnetic flux density, plate thickness, coating tension, and amount of impurities. , Specific resistance, crystal grain size, and the like.
Among them, high magnetic flux density and high specific resistance are important in reducing iron loss, and the development of a technology for manufacturing a product with as low an iron loss as possible at low cost is an issue.

A grain-oriented electrical steel sheet is manufactured by secondary recrystallization using an inhibitor of fine precipitates and texture control by cold rolling or primary recrystallization.
The height of the magnetic flux density depends on the inhibitor and the texture. And, in the grain-oriented electrical steel sheet, the specific resistance increases as the Si content increases, and the iron loss decreases.
When the Si content is increased, there is a problem that the texture is deteriorated. The iron loss is represented by a loss W17 / 50 when magnetized at 50 Hz to a magnetic flux density of 1.7 T.

By the way, the following four techniques are known as methods for producing typical grain-oriented electrical steel sheets which have been industrialized. The first technique is the M.I. F. Littma
nn is disclosed in Japanese Patent Publication No. 30-3651;
This is a double cold rolling method using S. However, the unidirectional magnetic steel manufactured by this method does not have a high magnetic flux density.
Is about 1.86 T and has a Goss orientation integration degree of about 0.92 to 0.93 relative to the saturation magnetic flux density Bs.

The second technique is disclosed by Taguchi et al.
This is a technique disclosed in Japanese Patent No. 5644 to make a final cold rolling reduction of 80% or more by using AlN + MnS.
In this technique, a high magnetic flux density can be obtained, but strict control of manufacturing conditions is required in industrial production. In the grain-oriented electrical steel sheet manufactured by this technology,
The magnetic flux density B8 is about 1.93T, and a Goss orientation integration degree of about 0.95 to 0.96 with respect to the saturation magnetic flux density Bs is obtained.

The third technology is described in Japanese Patent Publication No. 51-1 / 1987.
No. 3,469, MnS (and / or MnS)
This is a technique related to a double cold rolling method using nSe) + Sb. In the magnetic steel sheet obtained by this technology, the magnetic flux density is inferior to that of the second technology, and the magnetic flux density B8 is 1.90.
At about T, the Goss orientation integration degree is about 0.94 to 0.95 with respect to the saturation magnetic flux density Bs.

The above three techniques have the following problems in common. In each of these technologies, the inhibitor is formed before cold rolling. That is,
By increasing the slab heating temperature prior to hot rolling to more than 1250 ° C, in fact, to 1300 ° C or more,
The coarse precipitate is once dissolved, and the precipitate is finely and uniformly precipitated during the subsequent hot rolling or heat treatment. However, raising the slab heating temperature (high-temperature slab heating method) involves increasing the energy used during slab heating, increasing the equipment damage rate, etc., as well as reducing the yield due to scale loss and ear cracks, There is a problem such as the occurrence of linear secondary recrystallization failure due to the coarsening of the crystal structure, and this problem is particularly remarkable in thin materials and high Si materials.

As a fourth technique, a low-temperature slab heating method has been developed to solve the problem of the high-temperature slab heating method, which is disclosed in Japanese Patent Application Laid-Open Nos. 62-40315 and 5-112827. It is disclosed in the gazette. In this technology, the inhibitor required for secondary recrystallization is built into steel from the time after completion of decarburization annealing (primary recrystallization) to before the appearance of secondary recrystallization in finish annealing, thereby increasing the slab heating temperature. Is 1280 ° C. or less, which is comparable to ordinary steel. Inhibitors are (Al, Si) N formed by infiltrating N into steel. And the amount of precipitation can secure 3 times or more of the amount of precipitation in the conventional high-temperature slab heating method, so that the inhibitor is strong and has high thermal stability. As a means for infiltrating N into the steel, a means for infiltrating N from the atmosphere gas during the temperature rise process of the finish annealing, or a nitriding annealing of the strip in a continuous region after the decarburizing annealing or after the completion of the decarburizing annealing is performed. There are means. As the nitriding source, an annealing atmosphere gas mixed with NH ₃ or the like is used. With such a low-temperature slab heating method, a drastic cost reduction of the grain-oriented electrical steel sheet could be achieved.

In the above method, a high magnetic flux density equivalent to that of the second technique can be obtained by using a thermally stable inhibitor. The magnetic flux density B8 is 1.93
At about T, the Goss orientation integration degree is about 0.94 to 0.96 in a ratio to the saturation magnetic flux density Bs.

[0011]

In the production of a grain-oriented electrical steel sheet by the above-described low-temperature slab heating method, there is a problem of a linear secondary recrystallization defect caused by abnormal crystal grain growth, which occurs in the high-temperature slab heating method. And Si can be easily increased. Therefore, the present inventors have promoted high Si based on the low-temperature slab heating-single cold rolling method.However, while maintaining the process conditions including the component composition, the Si content in the steel is maintained. When the amount is increased, the magnetic flux density B8 is degraded, and it is difficult to obtain a predetermined low iron loss. The present inventors diligently investigated the cause. First, as the Si content increases, the saturation magnetic flux density Bs decreases. Therefore, as an index indicating the degree of azimuthal integration of Goss secondary recrystallization, B8 relative to the saturation magnetic flux density Bs is used. (B8 / Bs; hereinafter referred to as Goss orientation accumulation degree) is useful, and it is necessary to secure a required level of Goss orientation accumulation degree in order to achieve good iron loss characteristics. Was. However, even in terms of the Goss orientation integration degree, simply increasing the Si content deteriorates the Goss orientation integration degree, and a predetermined iron loss characteristic cannot be obtained. That is, the metallurgical change accompanying the increase of the Si content is clarified from both the inhibitor and the texture viewpoints, and the development of a compensation technique for securing a required level of Goss orientation integration even in a high Si material is an issue. Becomes

[0012]

Means for Solving the Problems The inventors of the present invention have investigated in detail the material change accompanying the increase in Si, and
In addition to elucidating the cause of the deterioration of the Goss orientation integration degree, the appropriate process conditions for increasing the Si in the low-temperature slab heating-nitriding manufacturing process were studied. First, it was clarified that the deterioration of the Goss orientation accumulation degree due to the increase in Si is due to the coarsening of the crystal grain size in the annealed hot-rolled sheet, and it is important to control the crystal grain size within a predetermined range. . Further, as a result of various studies of the above control method, the amount of the transformation phase was adjusted by adjusting the C content, and by this adjustment,
It has been found that the Goss orientation integration degree can be secured at a desired level, and that the iron loss characteristics can be improved in accordance with the Si content.

That is, the present invention is based on the above findings, and the gist thereof is as follows:
It is as shown in (3). (1) By weight%, C: 0.02 to 0.10%, Si:
2.5-4.0%, Mn: 0.05-0.45%, S and / or Se: 0.15% or less, acid-soluble Al:
0.020-0.035%, N: 0.0035-0.0
An electromagnetic steel slab consisting of 12%, the balance Fe and unavoidable impurities, is heated to a temperature of 1280 ° C. or less, hot-rolled, annealed, and cold-rolled at a rolling reduction of 80% or more, In a method for producing a grain-oriented electrical steel sheet to be subjected to decarburizing annealing, nitriding treatment and finish annealing, the average grain size of the non-transformed ferrite phase in the annealed hot-rolled sheet is controlled in a range of 28 to 85 μm. A method for producing a grain-oriented electrical steel sheet having a high degree of Goss orientation integration. (2) The non-transformed ferrite phase has an average crystal grain size of 35 to
(1) The method for producing a grain-oriented electrical steel sheet having a high degree of Goss orientation integration according to (1), wherein the grain size is controlled to be in a range of 65 μm. (3) In the electromagnetic steel slab, the C content (%) is set to 0.023 × Si (%) − according to the Si content (%).
0.032 ≦ C (%) ≦ 0.025 × Si (%)-0.
(1) or (2), wherein the Goss orientation is highly integrated.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First, the present invention will be described based on experimental results. % By weight, Mn: 0.1%, S: 0.007
%, Cr: 0.12%, acid-soluble Al: 0.029%,
N: 0.0083%, P: 0.030% as base component content, C: 0.021 to 0.095%, Si:
The electrical steel slab modified in the range of 5 to 4.5%
After heating at 0 ° C. for 60 minutes, hot rolling was performed to produce a hot-rolled sheet having a thickness of 2.3 mm. Then, this hot rolled sheet is
After annealing and heating at a temperature of + 900 ° C., it was rapidly cooled. The cross section of the hot rolled sheet after quenching was observed with an optical microscope, and the average value of the crystal grain size was measured.

The hot-rolled sheet is continuously pickled, and
It cold-rolled to the cold-rolled sheet of m thickness. This cold-rolled sheet was decarburized and annealed at different annealing temperatures to reduce the primary recrystallized grain size to 23 μm.
m. Thereafter, nitriding annealing was performed at 750 ° C. for 30 seconds in a mixed gas of hydrogen, nitrogen and ammonia to adjust the amount of nitrogen in the steel sheet to approximately 220 ppm. Then, Mg
An annealing separator containing O and TiO ₂ as main components is applied, and 12
Heat to 100 ° C at 10 ° C / hr, then 1200 ° C
For 20 hours. After the strain-annealed finish annealing plate, SST (Single Sheet Tes)
ter) to measure the magnetic properties. As for the magnetic flux density, since the saturation magnetic flux decreases with an increase in the Si content, magnetic steel materials having different Si contents have a magnetic flux density of B8
Cannot reflect the sharpness of Goss secondary recrystallization. Therefore, the Goss orientation integration degree was evaluated using the standard value of B8 / Bs.
Then, by the crystal orientation measurement by X-ray diffraction, B8 / B
The validity of s was confirmed.

FIG. 1 shows the average crystal grain size (μm) in the annealed hot rolled sheet and the Goss orientation integration (B8 /
Bs). The average crystal grain size for obtaining a high secondary recrystallization sharpness of B8 / Bs ≧ 0.94 is 28 to 85.
It was found to be in the range of μm. This is the first feature of the present invention. Here, this average crystal grain size 28
Within the range of ８５85 μm, the iron loss decreased with an increase in the Si content, and it was confirmed that the effect of increasing Si was exhibited. Iron loss improvement cost is 0.1% Si
It was about 0.015 W / kg at W17 / 50 per content.

The mechanism by which the grain size of the annealed hot-rolled sheet affects the sharpness of the secondary recrystallization is not clear at present, but is considered as follows. As described above, the degree of Goss orientation accumulation in a grain-oriented electrical steel sheet is considered to depend on the inhibitor strength and the primary recrystallization texture, but in the present invention, mainly the influence of the primary recrystallization texture is large. it is conceivable that.

In general, in the primary recrystallization, the Goss orientation as a secondary recrystallization nucleus and the [111] <211> orientation corresponding to the Goss nucleus may be considered. In the Goss orientation, the deformation zone formed in the crystal grain by cold rolling is used as a generation site, and it is considered that the larger the crystal grain size before cold rolling, the larger the number of goss nuclei. On the other hand, [11
1] <211> indicates that the vicinity of the crystal grain boundary before cold rolling is a recrystallization generation site, and that the crystal grain size before cold rolling is small,
[111] <211> is considered to increase. Therefore, if the crystal grain size in the annealed hot-rolled sheet is too small, goss nuclei for primary recrystallization will be insufficient, and good secondary recrystallization Goss orientation and grain size cannot be obtained.

Conversely, if the crystal grain size in the annealed hot-rolled sheet is too large, the (111) <211> orientation corresponding to the Goss nucleus of the primary recrystallization decreases, and therefore, a high magnetic flux is stably obtained. It is considered disadvantageous for obtaining density.
In the low-temperature slab heating method based on the present invention, the crystal grain size before cold rolling is 2 due to the above texture.
8-35 μm is considered appropriate. On the other hand, as disclosed in Japanese Patent Application Laid-Open No. 9-31637, for example, according to a study by the present inventors, in a technique based on a so-called high-temperature slab heating method, an appropriate crystal grain size before cold rolling is used. Is 10 to 25 μm, which is significantly smaller than the proper crystal grain size in the present invention. Although the reason for this is not clear, in the method disclosed in the above publication, the thermal stability of the inhibitor is lower than that in the low-temperature slab heating method. It is thought that having to weaken power is involved.

Next, a description will be given of the results of experiments in which measures for controlling the average crystal grain size in the annealed hot-rolled sheet were examined.
Si and C for B8 / Bs arranged from the above experimental results
The effect of each amount (%) is shown in FIG. The measured values of the average crystal grain size are shown in the figure, but the Si content (%) is large or C
It can be seen that the smaller the amount (%), the larger the crystal grain size. As shown in FIG. 1, when the average grain size of the annealed hot-rolled sheet is 28 to 85 μm, B8 / Bs ≧ 0.94
In order to obtain this crystal grain size, 0.023 × Si (%) − 0.032 ≦ C (%) ≦ 0.
It is understood that the C amount (%) needs to be adjusted within the range of 025 × Si (%) − 0.010. This is the second feature of the present invention.

A metallurgical view of the second feature is as follows. Generally, it is known that Si is an austenite loop element and C is an austenite expanding element. Therefore, when the Si content (%) is increased, the austenite transformation rate in the heat history from slab heating to hot-rolled sheet annealing decreases. Since austenite suppresses ferrite grain growth, S
It is considered that the crystal grain size in the annealed annealed sheet increases with an increase in the i amount (%). Therefore, from the viewpoint of increasing the C content (%) and securing the austenite transformation rate, the C content (%) increases with the Si content (%).
It is thought that the appropriate range of the shift will also be higher.

Next, the reasons for limiting the component composition of the electromagnetic steel slab in the present invention will be described. C is required to be 0.02% or more in order to improve the hot-rolled microstructure by utilizing the γ transformation, but if it exceeds 0.10%, the decarburization annealing time becomes longer, and the productivity is impaired. The upper limit is set to 0.10%. In addition, as described above, the C amount (%) varies from “0.023 × Si (%) − 0.032” to the Si amount (%).
It is adjusted within the range of “0.025 × Si (%) − 0.010”. If the C amount (%) is less than the above range, the secondary recrystallization becomes unstable, and even in the case of the secondary recrystallization, the Goss orientation integration degree (B8 / Bs) is as low as 0.94 or less. On the other hand, when the C content (%) exceeds the above range, the secondary recrystallization is stabilized, but the Goss orientation integration degree is also deteriorated.

Si is an important element for effectively increasing the specific resistance of the product and obtaining a low iron loss, and its content is determined according to the iron loss to be aimed. If the content is less than 2.5%, it is difficult to obtain a product with a low iron loss. On the other hand, if the content is more than 4.0%, a problem occurs in the cold rolling property of the material.
4.0%. One of the characteristics of the component composition of the electromagnetic steel slab according to the present invention is that S and / or Se are set to 0.1%.
015% or less, preferably 0.007% or less. As is well known, S forms MnS and Se forms MnSe, and acts to suppress grain growth. In the present invention, the inhibitor required to develop secondary recrystallized grains is characterized by being built in the steps after decarburizing annealing, and fine precipitates are dispersed before cold rolling, In the present invention in which the primary recrystallization grain size is adjusted to obtain a high magnetic flux density and a low iron loss, it is not preferable. Therefore, S
And / or Se is set to 0.015% or less. In addition, reducing the amount of S and / or Se is also highly effective in reducing edge cracking during hot rolling.

Although Al combines with N to form AlN, in the present invention, it is necessary to form (Al, Si) N by nitriding the steel after the completion of the primary recrystallization. Since it is essential, a certain amount of free Al is required. Therefore, as acid-soluble Al,
0.020-0.035% is added. N is 0.003
It needs to be 5 to 0.012%. If it exceeds 0.012%, blisters on the steel sheet surface called blisters occur. In addition, it becomes difficult to adjust the primary recrystallization structure. The lower limit is preferably 0.0035%. If the value is less than this value, it becomes difficult to develop secondary recrystallized grains.

If the content of Mn is too small, secondary recrystallization becomes unstable, while if it is too large, it becomes difficult to obtain a product having a high magnetic flux density. The appropriate content is 0.05-
0.45%. In addition, trace amounts of Cr, Sn, P, C
Including u, Sb, Ni, Bi and the like does not impair the gist of the present invention.

Next, the manufacturing process of the present invention will be described. The electromagnetic steel slab is obtained by melting in a melting furnace such as a converter or an electric furnace, performing a vacuum degassing treatment as necessary, and then performing continuous casting or slab rolling after ingot making. Thereafter, slab heating is performed prior to hot rolling. In the manufacturing process of the present invention, slab heating is performed at a low temperature of 1280 ° C. or less. This low-temperature slab heating reduces the consumption of heating energy and causes the AlN in the steel to be in an incomplete solid solution state without completely dissolving the AlN in the steel. In addition, MnS having a high solid solution temperature naturally becomes an incomplete solid solution state by the low-temperature slab heating. Immediately after the slab is heated, it is hot-rolled into a hot-rolled sheet having a thickness of 2 to 3 mm through rough hot rolling and finish hot rolling by a usual method.

The hot rolled sheet is annealed in a usual manner. The condition of the hot-rolled sheet annealing may be a known method, but usually 900 to 11
Anneal at a temperature of 70 ° C. for about 30 to 500 seconds, and then cool rapidly. As described above, the present invention is characterized in that the average crystal grain size in the annealed hot-rolled sheet is controlled within a range of 28 to 85 μm, preferably 35 to 65 μm. The method for measuring the average crystal grain size is as follows: in the thickness direction of the steel sheet, in a region extending from one surface layer to the other surface layer in a cross section parallel to the hot rolling direction, the number of 1000 or more crystal grains is measured. Is calculated by converting the area of to the equivalent circle diameter. The number measurement is performed on the old ferrite structure except for the fine bainite and pearlite structures corresponding to the old austenite phase. Note that the particle size may be measured using an image analysis processing device or the like. The cross section to be measured may be perpendicular to the hot rolling direction, but since the crystal grains are stretched in the hot rolling direction, the average particle size value is slightly reduced to 80 to 90% of the perpendicular direction.

Next, the process conditions after the cold rolling will be described. The present invention is based on the premise that once cold-rolled sheet annealing is performed, one-time cold rolling under high pressure is performed from the viewpoint of achieving low cost. Cold rolling is performed by a usual method. To obtain a high magnetic flux density,
It is preferable to increase the draft and to perform aging treatment between passes. Decarburizing annealing is performed on the cold-rolled sheet cold-rolled to the final sheet thickness. In addition to decarburization, decarburization annealing has a role of adjusting the primary recrystallization structure and generating an oxide layer necessary for forming a film. The decarburization annealing is usually performed in a temperature range of 800 to 900 ° C. in wet hydrogen and nitrogen gas.

Next, a nitriding treatment is performed. The conditions for the nitriding treatment may be known conditions, and it is advantageous for the nitriding to set the annealing temperature to 650 to 850 ° C. In order to stably develop good secondary recrystallized grains, the nitrogen content is required to be 120 ppm or more, preferably 150 ppm or more. Thereafter, a slurry mainly containing MgO and TiO ₂ is applied by a known method, and finish annealing is performed at a temperature of 1100 ° C. or more. The condition of the finish annealing may be a known condition, and it is effective to adjust the atmosphere or reduce the heating rate in order to increase the degree of Goss orientation accumulation.

[0030]

EXAMPLES In weight%, Mn: 0.10%, S: 0.00
7%, Cr: 0.12%, acid-soluble Al: 0.028
%, N: 0.0084%, P: 0.025%, and after heating an electromagnetic steel slab having a C content (%) and a Si content (%) adjusted as shown in Table 1, at 1150 ° C. Hot rolling was performed to obtain a 2.0 mm hot-rolled sheet. Then 1120 ° C +
After annealing at 900 ° C., the steel sheet was rapidly cooled. Table 1 shows the average crystal grain size after annealing. Then, after pickling, 0.2
It was cold-rolled into a cold-rolled sheet having a thickness of 2 mm. This was decarburized and annealed in a wet hydrogen and nitrogen atmosphere. At this time, the annealing temperature was adjusted so that the particle size of the primary recrystallized grains was about 23 μm.

Thereafter, nitriding annealing was carried out at 750 ° C. for 30 seconds in a mixed gas of hydrogen, nitrogen and ammonia to adjust the amount of nitrogen in the steel sheet to 215 ppm. Then, MgO,
An annealing separator containing TiO ₂ as a main component is applied, and 1200
Finish annealing was performed at 20 ° C. × 20 hours. The magnetic flux density B8 was measured after the finish annealed plate was annealed for distortion removal. Then, after applying a tension coating mainly composed of colloidal silica and aluminum phosphate and baking, in the cold rolling direction,
Laser irradiation magnetic domain control is performed at 5 mm intervals, and iron loss W17
/ 50 was measured. Table 1 shows the results.

[0032]

[Table 1]

From Table 1, it can be seen that good iron loss is obtained under the conditions satisfying the conditions of the present invention.

[0034]

According to the present invention, in a process premised on a low-temperature slab heating-nitriding method having high cost merit,
It is possible to manufacture a grain-oriented electrical steel sheet having a high Si content, a high Goss orientation integration degree, and a good iron loss.

[Brief description of the drawings]

FIG. 1 shows the average crystal grain size and the degree of secondary recrystallization Goss orientation integration (B8 /
It is a figure which shows the relationship of Bs).

FIG. 2 is a graph showing the relationship between the C content (%) and Si content (%), the degree of secondary recrystallization Goss orientation integration (B8 / Bs), and the average crystal grain size.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification FI FI Theme Court ゛ (Reference) H01F 1/16 H01F 1/16 B (72) Inventor Takashi Mogi 1-1 Tobata-cho, Tobata-ku, Kitakyushu-shi, Fukuoka Prefecture Inside Nippon Steel Corporation Yawata Works (72) Kenichi Murakami 1-1 1-1 Tobata-cho, Tobata-ku, Kitakyushu-shi, Fukuoka Prefecture Inside Nippon Steel Corporation Yawata Works (72) Inventor Tomoji Kumano Fukuoka Prefecture 1-1 Nippon Steel Corporation, Yawata Works, Tobata-ku, Kitakyushu City (72) Katsuro Kuroki Inventor F-term in Nippon Steel Plant Design Co., Ltd., 46-46 Nakahara, Tobata-ku, Kitakyushu, Fukuoka 4K033 AA02 CA07 CA09 CA10 DA01 DA02 FA01 FA12 HA02 JA04 JA07 5E041 AA02 AA19 CA02 HB05 HB07 HB11 NN01 NN06 NN17 NN18

Claims (3)

[Claims] C .: 0.02 to 0.10%, Si: 2.5 to 4.0%, Mn: 0.05 to 0.45%, S and / or Se: 0. 015% or less, acid-soluble Al: 0.020 to 0.035%, N: 0.0035 to 0.012%, and the balance of Fe and unavoidable impurities to the electromagnetic steel slab,
After being heated to a temperature of 1280 ° C. or less, hot-rolled, annealed hot-rolled sheet, cold-rolled with a reduction of 80% or more, and then subjected to decarburizing annealing, nitriding treatment, and finish annealing. A method for producing a magnetic steel sheet, wherein the average grain size of the non-transformed ferrite phase in the annealed hot-rolled sheet is controlled in the range of 28 to 85 µm. . 2. The method according to claim 1, wherein the average grain size of the non-transformed ferrite phase is controlled in a range of 35 to 65 μm. 3. In the electromagnetic steel slab, the C content (%) is set to 0.023 × Si (%) − 0.032 ≦ C (%) ≦ 0 according to the Si content (%).
3. The method according to claim 1, wherein the adjustment is performed within a range of 025 × Si (%) − 0.010.
A method for producing a grain-oriented electrical steel sheet having a high degree of Goss orientation integration according to the description.