JP4306259B2 - Method for producing grain-oriented electrical steel sheet - Google Patents

Description

【００４９】
実施例２
Ｃ：0.04mass％以下、Si：3.4mass％、Sn:0.05mass％、sol.Alを0.014mass％およびＮを55ppm含有し、Ｓを８ppm，Seを３ppm，その他の成分を各々30ppm未満に低減した成分の鋼スラブを連続鋳造にて製造した。このスラブを1230℃で60分加熱し、熱間圧延にて2.2mm厚に仕上げた。熱延板焼鈍を1050℃で60秒均熱する条件で行った。その後、130℃の温度の冷間圧延にて0.30mmの最終板厚に仕上げた。ついで水素25vol％、窒素76vol％、850℃で露点を変更して、均熱60秒の脱炭量を変える再結晶焼鈍を行った。その後、焼鈍分離剤を適用することなく露点−20℃の窒素雰囲気中で850℃までを50℃/ｈで加熱し、850℃以上をAr雰囲気として10℃／ｈで1000℃まで加熱する方法にて最終仕上焼鈍を行った。焼鈍後900℃で20秒間、湿水素雰囲気により脱炭を兼ねる平坦化焼鈍を行った後、重クロム酸アルミニウム、エマルジョン樹脂、エチレングリコールを混合したコーティング液を塗布して300℃で焼き付けて製品とした。
【００５０】
かくして得られた製品板の圧延方向および圧延直角方向の磁気特性を表２に示す。この表２によれば、AlNを含有しS、Se量を低減した素材を用い、スラブ加熱温度を1200℃以上とすること、最終仕上焼鈍で焼鈍分離剤を適用しないこと、さらに最終仕上焼鈍前にＣ量を0.01〜0.025mass％確保することで、圧延方向の磁束密度が極めて高く、圧延直角方向の低磁化力での磁束密度Ｂ_１が0.7Ｔ以上の製品が得られていることがわかる。
【００５１】
【表２】

【００５２】
実施例３
表３の成分からなる鋼スラブを、1250℃に加熱し熱間圧延にて3.2mm厚に仕上げた。なお、表３に示されない成分に関しては、すべて各々50ppm以下に低減した。熱延板焼鈍を1000℃で均熱60秒の条件で行った。その後、冷間圧延で0.50mmの最終枚厚に仕上げた。ついで、水素75vol％、窒素25vol％、露点−25℃の雰囲気で940℃で均熱20秒の再結晶焼鈍を行った。そして、焼鈍分離剤としてコロイダルシリカを適用し、窒素雰囲気中で850℃まで10℃／ｈで昇温し50時間保持した後、水素雰囲気に切り替え、1050℃まで20℃／ｈの速度で昇温する最終仕上焼鈍を行った。ついで、875℃での平坦化焼鈍を施した後、重クロム酸アルミニウムを主体とした無機コーティング液を塗布して250℃で焼き付けて製品とした。
【００５３】
かくして得られた製品板の圧延方向、および圧延直角方向の磁気特性を表３に示す。表３によれば、AlNを含有しS，Se量を低減した素材を用い、スラブ加熱温度を1200℃以上とし、さらに最終仕上焼鈍で焼鈍分離剤を適用しないことで、圧延方向の磁束密度が極めて高く、圧延直角方向の低磁化力での磁束密度Ｂ_１が0.7Ｔ以上の製品が得られていることがわかる。
【００５４】
【表３】

【００５５】
【発明の効果】
本発明によれば、EIコア、発電機用コアまたは分割型モータ用コアのように、圧延方向および圧延直角方向の磁化特性を重視し、かつ打抜加工で作製される鉄心の大量生産に好適である、フォルステライト被膜を有しない高磁束密度の方向性電磁鋼板を得ることができる。
【図面の簡単な説明】
【図１】 素材S量と圧延方向の磁束密度との関係を示す図である。
【図２】 素材S量と圧延直角方向の磁束密度（B_lおよびB₈）との関係を示す図である。
【図３】 素材S量と圧延方向の鉄損の関係を示す図である。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method of manufacturing a grain-oriented electrical steel sheet mainly used for iron core materials of large motors and generators.
[0002]
[Prior art]
Oriented electrical steel sheets are used for iron core materials for large generators and transformers, with an emphasis on energy loss due to iron loss. In an iron core (stator) of a large generator that uses this directional electromagnetic steel sheet in a stacked manner, a method of stacking and assembling segments obtained by punching the directional electromagnetic steel sheet into a fan shape is used. When using such a laminating method, it is necessary to punch into a complicated shape centering on the teeth part, and since a core material of several tons or more is used, the number of punches is enormous, so the punching die There is a need for a grain-oriented electrical steel sheet with low wear and good punchability.
[0003]
The surface of the grain-oriented electrical steel sheet is usually provided with a base film (glass film) mainly composed of forsterite (Mg ₂ SiO ₄ ), but it is an organic resin film coated on the non-oriented electrical steel sheet. Compared with, the forsterite film is remarkably hard and the die wear is large. For this reason, it is necessary to re-grind or replace the mold frequently, resulting in a reduction in work efficiency and an increase in cost at the time of iron core processing by the customer. Similarly, the slit property and the cut property are also deteriorated by the presence of the forsterite film.
[0004]
Here, in order to improve the punchability of grain-oriented electrical steel sheets, it is common to remove the forsterite film by a method such as pickling or grinding. There is a big problem that the magnetic properties are deteriorated.
[0005]
On the other hand, Patent Document 1 and Patent Document 2 disclose a technique for suppressing the formation of forsterite membrane by blending a chemical in an annealing separator mainly composed of MgO applied during finish annealing. In addition, technologies for applying an annealing separator mainly composed of silica and alumina to a material containing Mn have been proposed.
[0006]
[Patent Document 1]
Japanese Patent Publication No. 6-49948 [Patent Document 2]
Japanese Patent Publication No. 6-49949 [Patent Document 3]
Japanese Patent Laid-Open No. 8-134542
[Problems to be solved by the invention]
In these methods, forsterite is often formed partially due to fluctuations in the finish annealing atmosphere between the layers of the coil, and it has been extremely difficult to obtain a product plate in which the formation of forsterite is completely suppressed.
[0008]
Furthermore, when a grain-oriented electrical steel sheet is applied as a core material for a large motor or generator, magnetization in the direction perpendicular to the rolling direction as well as the rolling direction is required. For this perpendicular to the rolling direction of the magnetization, as compared to the rolling direction, the magnetic flux density under a relatively low magnetic force, for example by improving the magnetic flux density B ₁ in the magnetization force 100A / m, smoothly ac magnetization in the iron core Is done.
[0009]
However, the B ₁ value in the direction perpendicular to the rolling of the current grain-oriented electrical steel sheet is 0.5T or less, which is significantly lower than the B ₁ value in the rolling direction of about 1.8T. As a result of the increased iron loss, the good iron loss of the grain-oriented electrical steel sheet cannot be effectively exhibited in the motor core and the EI core.
[0010]
As described above, a material satisfying both magnetic characteristics and punching workability, which is ideal as a core material for large motors and generators, has not yet been provided by conventional techniques.
Therefore, the present invention is intended to provide a completely new grain-oriented electrical steel sheet that is excellent in punching workability and magnetic characteristics, particularly in the direction perpendicular to the rolling direction.
[0011]
[Means for Solving the Problems]
The inventors have intensively studied the means for solving the above problems. First, in order to suppress the formation of the forsterite film, the MgO that is usually used as an annealing separator is not used. It is difficult to purify due to the non-use of S, Se, it is possible to improve the magnetic flux density in the rolling direction and in the direction perpendicular to the rolling direction by reducing S and Se at the material stage, and further using AlN alone as an inhibitor. I found it.
[0012]
Hereinafter, experiments that have made the present invention successful will be described.
The inventors have C: 0.04 mass% or less, Si: 3.4 mass%, Mn: 0.15 mass%, Sn: 0.04 mass%, sol. Al: 0.015 mass%, and N: 60 massppm (hereinafter simply indicated as ppm). Steel slabs containing various amounts of S and various other components reduced to 30 ppm or less were produced by continuous casting. Then, after heating to 1220 ° C., the thickness was finished to 2.4 mm by hot rolling. The hot rolled sheet was soaked in a nitrogen atmosphere at 1000 ° C. for 1 minute and then rapidly cooled. Subsequently, cold rolling was performed to obtain a final thickness of 0.35 mm. Thereafter, recrystallization annealing was performed in an atmosphere of 20 vol% hydrogen, 80 vol% nitrogen, and a dew point of 30 ° C at 850 ° C, which also served as decarburization for 60 seconds. And the test piece was cut out from the coil after recrystallization annealing, and the experiment which changes various final finish annealing conditions was done. Furthermore, the annealing experiment was performed separately for the conditions using MgO as an annealing separator and the conditions for not using MgO. The final finish annealing is performed at a temperature of 50 ° C / h from room temperature to a holding temperature of 850 ° C in a nitrogen atmosphere with a zero point of -20 ° C and held for 50 hours. After holding, 20 ° C in an Ar atmosphere or nitrogen atmosphere The temperature was raised to 1000 ° C. at / h.
[0013]
After the final finish annealing, the magnetic properties in the rolling direction and the direction perpendicular to the rolling were measured. The result is shown in FIG. 1 as the relationship between the amount of S and the magnetic flux density in the rolling direction. Regarding the magnetic flux density in the rolling direction, the amount of S was almost constant up to 50 ppm, but it deteriorated greatly when it exceeded 50 ppm. Here, when the sample after finish annealing was investigated, it was found that when the amount of S exceeded 50 ppm, the development of secondary recrystallized grains was insufficient.
[0014]
FIG. 2 shows the relationship between the amount of S and the magnetic flux density in the direction perpendicular to the rolling. Regarding the magnetic flux density in the direction perpendicular to the rolling direction, there is almost no difference in the value of the magnetic flux density B ₈ at high magnetizing force between the condition using MgO as an annealing separator and the case without using MgO. the magnetic flux density under a force, that is, the value of B ₁ represents, in particular when the amount of S is small, if not using MgO becomes remarkably good. When MgO was used as the annealing separator, a forsterite film was formed on the surface, and when MgO was not used, silica (SiO ₂ ) was formed.
[0015]
From the above experiment, it is possible to improve the magnetic flux density in the rolling direction by reducing the S content to 50 ppm or less, and further to suppress the formation of the forsterite film without applying MgO as an annealing separator. It has been newly found that the value of the magnetic flux density at a low magnetization force is improved.
[0016]
Further, FIG. 3 shows the influence of the amount of S, the annealing atmosphere, and whether or not MgO is applied on the iron loss value in the rolling direction.
When MgO was not applied and when the atmosphere was switched to Ar after holding, the iron loss was good when the S content was in the range of 50 ppm or less, whereas when the switch was not switched, the iron loss value deteriorated. The amount of nitrogen in the steel after the final finish annealing was examined, and when it was switched to Ar atmosphere, it was reduced to 10 ppm or less, but in the nitrogen atmosphere it was 80 ppm, increasing from 60 ppm in the material. Further, regarding the amount of S in the ground iron after the final finish annealing, the amount remained almost equal to that in the material in any atmosphere.
[0017]
On the other hand, when MgO is applied, N in the iron after finishing annealing remains at 30-50 ppm in the Ar atmosphere, remains at 80-100 ppm in the nitrogen atmosphere, and denitrification is inhibited compared with the case where MgO is not applied. It was. Regarding the amount of S after final finish annealing, it was less than half in any atmosphere.
[0018]
From the above experiments and investigations, N can be reduced by switching the annealing atmosphere at 850 ° C. or higher to Ar when MgO is not applied, but S can be reduced during annealing. It became clear that there was no. On the other hand, when MgO was applied, it became clear that denitrification was rather hindered and disadvantageous, whereas the amount of S in the railway was advantageously reduced.
[0019]
Based on the above experiment, if an ingredient containing AlN alone is used as an inhibitor, and a component system that reduces the inhibitor containing S and Se as much as possible is used, MgO is not applied to the annealing separator. Thus, the present invention has been completed by newly discovering that nitrogen can be reduced by switching the final annealing atmosphere to a non-nitriding atmosphere such as Ar and that good iron loss can be obtained.
[0020]
That is, the gist configuration of the present invention is as follows.
(1) C: 0.08 mass% or less, Si: 1.0 mass% to 4.0 mass%, Mn: 0.005 to 3.0 mass%, sol. Al: 0.010 to 0.030 mass% and N: 30 to 100 massppm, S and Se each have a reduced component composition below 50Massppm, a steel slab to a balance of Fe and unavoidable impurities ing, the hot-rolled sheet obtained by hot rolling after heating to 1200 ° C. or higher, 1 When the final finishing annealing is performed without applying the MgO-based annealing separator , the final finishing annealing is performed. conducted at 1000 ° C. or less of the temperature range, the temperature range of not lower than 850 ° C. wherein the nitrogen content of the atmosphere of less than 50 vol%, the magnetic flux density B ₁ in the direction perpendicular to the rolling direction is a and forsterite or 0.7T A method for producing a grain-oriented electrical steel sheet having no underlying coating as a main component.
[0023]
( 2 ) The method for producing a grain-oriented electrical steel sheet according to the above (1 ), wherein the amount of C before the start of final finish annealing is controlled in the range of 0.010 to 0.025 mass%.
[0024]
( 3 ) Steel slab is further added to Sb: 0.01 to 0.50 mass%, Sn: 0.01 to 0.50 mass%, Ni: 0.01 to 1.50 mass%, Cu: 0.01 to 0.50 mass%, P: 0.0005 to 0.50 mass%, and Cr: The method for producing a grain-oriented electrical steel sheet according to the above (1) or (2) , which has a component composition containing at least one selected from O.01 to 1.50 mass%.
[0025]
DETAILED DESCRIPTION OF THE INVENTION
According to the present invention, by suppressing the formation of the forsterite film without applying MgO as an annealing separator, the magnetic flux density B ₁ at a low magnetization force in the direction perpendicular to the rolling can be as high as 0.7 T or more. Is not necessarily clear, but the inventors consider as follows.
[0026]
Well, forsterite coating is well known to contribute to the reduction of iron loss in the rolling direction by imparting tension to the steel sheet surface in the rolling direction, and further vitrifies at high temperature for imparting tension. It is very common in the manufacturing method for grain-oriented electrical steel sheets to apply a tension coating mainly composed of phosphate or the like on the top. The tension exerted by the forsterite is estimated to be about 3 to 5 MPa when the amount of warpage of the steel sheet is measured and evaluated. By the way, the 180 ° magnetic domain has only a magnetization component in the rolling direction, and magnetization in the direction perpendicular to the rolling cannot be performed by the domain wall movement of the 180 ° magnetic domain. When tension is applied to the surface of the steel sheet by the forsterite coating, the 180 ° magnetic domain structure is stabilized by the magnetoelastic effect, and magnetization in the direction perpendicular to the rolling is hindered. It is estimated that the density decreases.
[0027]
In the technology for forming forsterite film using ordinary inhibitors, low iron loss cannot be obtained unless the inhibitor-forming components (S, Se, N, etc.) are purified by high temperature annealing exceeding 1100 ° C. In the method in which the forsterite film is not formed without applying MgO, it is possible to purify nitrogen at a low temperature of 1000 ° C. or lower. That is, the purification of N proceeds by decomposing and releasing into an annealing atmosphere, so it is considered advantageous not to form a forsterite film. Further, since the reduction of S and Se is reduced by a mechanism that attracts from the ground iron by concentrating in the forsterite film, it is considered that the purification does not proceed when the forsterite film is not formed.
[0028]
The grain-oriented electrical steel sheet according to the present invention, like an EI core, a generator core or a split motor core, emphasizes the magnetization characteristics in the rolling direction and the direction perpendicular to the rolling direction, and has a large amount of iron core produced by punching. Suitable for production.
[0029]
Next, the reason for limitation of the molten steel component at the time of manufacturing the electrical steel sheet of the present invention will be described below.
If C exceeds 0.08 mass%, it will be difficult to finally reduce it to 50 ppm or less at which no magnetic aging occurs, so it is limited to 0.08 mass% or less. Furthermore, it is particularly desirable to reduce it to 50 ppm or less at the raw material stage in order to perform recrystallization annealing in a dry atmosphere and omit decarburization.
[0030]
Here, in the case of a material having a high amount of C, it is possible to decarburize in an oxidizing atmosphere during recrystallization annealing or planarization annealing after final finish annealing. In particular, in order to improve the magnetic flux density, if the C content is 0.01 to 0.025 mass% before the final finish annealing, the selectivity of the secondary recrystallization orientation can be improved. In this case, if the amount of C before final finish annealing is less than 0.01 mass%, there is no effect of improving the magnetic flux density, and if it exceeds 0.025 mass%, the development of secondary recrystallized grains is inhibited by the γ transformation. .
[0031]
Mn is an element necessary for improving the hot workability, but if it is less than 0.005 mass%, there is no effect, while if it exceeds 3.0 mass%, the magnetic flux density decreases, so 0.005 to 3.0 mass% And
[0032]
so1.Al is necessary to form AlN as an inhibitor. However, if the content is less than 0.01 mass%, the sharpness of the secondary recrystallization orientation decreases and the magnetic flux density decreases, and 0.03 mass%. If exceeded, secondary recrystallization becomes incomplete and the magnetic flux density decreases, so it is limited to 0.01 to 0.03 mass%.
[0033]
N is also necessary to form AlN as an inhibitor, but if the content is less than 30 ppm, the sharpness of the secondary recrystallization orientation decreases and the magnetic flux density decreases. On the other hand, if it exceeds 100 ppm, secondary recrystallization occurs. Since it becomes imperfect and the magnetic flux density decreases, it is limited to 30-100 ppm.
[0034]
Further, since S and Se, which are inhibitor forming elements, are difficult to remove in the final finish annealing and remain and deteriorate iron loss, it is advantageous to reduce them to 50 ppm or less, preferably 20 ppm or less, respectively.
[0035]
It is also desirable to reduce other impurity elements such as Ti, V, and Nb that form other carbides that are difficult to purify to 50 ppm or less.
That is, Ni can be added to improve the hot rolled sheet structure and improve the magnetic properties. If the amount of Ni added is less than 0.01 mass%, the amount of improvement in magnetic properties is small. On the other hand, if it exceeds 1.50 mass%, secondary recrystallization becomes unstable and the magnetic properties deteriorate, so the amount added is 0.01 to 1.50 mass. %.
[0036]
Moreover, at least 1 chosen from Sn: 0.01-1.50mass%, Sb: 0.01-0.50mass%, Cu: 0.01-1.50mass% and P: 0.005-0.50mass% for the purpose of improving an iron loss. Seeds can be added alone or in combination. When the addition amount is less than the lower limit amount, there is no effect of improving iron loss, and when the upper limit amount is exceeded, the development of secondary recrystallized grains is suppressed.
[0037]
The molten steel having the above components may be formed into a slab by a normal normal ingot forming method or a continuous casting method, or a thin cast piece having a thickness of 100 mm or less may be produced by a direct casting method. Subsequent hot rolling requires that the inhibitor components Al and N be completely dissolved in the slab, and that a uniform fine dispersion state is obtained that allows secondary recrystallization to be satisfactorily obtained. It is.
[0038]
Next, hot-rolled sheet annealing is performed as necessary. The hot-rolled sheet annealing temperature is preferably 850 ° C. or higher and 1150 ° C. or lower in order to develop a goth structure at a high level in the product plate. If the hot-rolled sheet annealing temperature is lower than 850 ° C, the band structure in hot-rolling remains, and if it exceeds 1150 ° C, the grain size after hot-rolled sheet annealing becomes too coarse, and the development of the goth structure of the product sheet respectively. Since the magnetic flux density decreases and the hot rolled sheet annealing temperature is preferably in the range of 850 to 1150 ° C.
[0039]
After hot-rolled sheet annealing, recrystallization annealing is performed after performing at least one cold rolling with intermediate annealing as required. The point of developing the goth structure is that the temperature of the cold rolling is raised to 100 ° C to 250 ° C and that the aging treatment in the range of 100 to 250 ° C is performed once or a plurality of times during the cold rolling. It is effective in.
The recrystallization annealing after the final cold rolling is preferably performed in the range of 800 to 1000 ° C.
[0040]
Here, when a material having a high C content is used, decarburization may be performed simultaneously in a wet hydrogen atmosphere. Further, the magnetic flux density can be improved by setting the C amount after decarburization annealing to 0.01 to 0.025 mass%.
[0041]
A technique for increasing the amount of Si by a siliconization method after final cold rolling or after recrystallization annealing may be used in combination. Further, it is possible to increase the magnetic flux density by increasing nitrogen and increasing the inhibitor by using a nitriding atmosphere such as ammonia during recrystallization annealing or during recrystallization annealing.
[0042]
Then, finish annealing without applying MgO-based sinter separation agent completely eliminates the formation of forsterite, good punching properties and good magnetization characteristics in the direction perpendicular to the rolling with low magnetizing force, That is, it is essential for obtaining B ₁ ≧ 0.7T.
[0043]
A secondary recrystallization structure is developed by performing final finish annealing. Although the final finish annealing needs to be performed at 800 ° C. or higher for secondary recrystallization, the heating rate up to 800 ° C. does not have a great influence on the magnetic properties, and may be under any conditions. It is particularly advantageous that the finish annealing atmosphere is a non-chambered atmosphere at a high temperature range of 850 ° C. or higher and the nitrogen content in the steel sheet steel is reduced to 50 ppm or less.
[0044]
After finish annealing, flattening annealing is performed, and tension is applied to correct the shape. In the case of using laminated steel plates, in order to improve iron loss, it is effective to apply an insulating coating to the steel plate surface after planarization annealing. An organic or semi-organic coating containing a resin is desirable to ensure good punchability, but an inorganic coating is applied when weldability is important.
[0045]
【Example】
Example 1
C: 0.03 mass% or less, Si: 3.4 mass%, Sn: 0.03 mass%, sol.Al: 0.019 mass%, and 70 ppm N, S 5 ppm, Se less than 2 ppm, and other components less than 30 ppm each A steel slab having a component composition reduced to 2 was produced by continuous casting. This slab was heated at the temperature shown in Table 1 for 60 minutes and finished to a thickness of 2.2 mm by hot rolling. Hot-rolled sheet annealing was performed at 1050 ° C. for 60 seconds. Then, it was finished to a final thickness of 0.30 mm by cold rolling at a temperature of 130 ° C.
[0046]
Next, recrystallization annealing was performed at 25% by volume of hydrogen, 75% by volume of nitrogen, and 850 ° C., which also served as decarburization for 60 seconds. Then, heating to 850 ° C at 50 ° C / h in a nitrogen atmosphere with a dew point of -20 ° C without applying a pure separation agent, and heating to 850 ° C or higher to 1000 ° C in an Ar atmosphere at 10 ° C / h The final finish annealing was performed at After annealing, planarization annealing was performed at 900 ° C. for 20 seconds, and then a coating solution in which aluminum dichromate, emulsion resin, and ethylene glycol were mixed was applied and baked at 300 ° C. to obtain a product.
[0047]
Table 1 shows the magnetic properties of the product plate thus obtained in the rolling direction and in the direction perpendicular to the rolling direction. From Table 1, using a material containing AlN and reducing the amount of S and Se, the slab heating temperature is set to 1200 ° C. or higher, and the annealing separator is not applied in the final finish annealing, so that the magnetic flux density in the rolling direction is high, it can be seen that the magnetic flux density B ₁ in a low magnetization of the perpendicular to the rolling direction is obtained more products 0.7 T.
[0048]
[Table 1]

[0049]
Example 2
C: 0.04 mass% or less, Si: 3.4 mass%, Sn: 0.05 mass%, sol.Al 0.014 mass% and N 55 ppm, S 8 ppm, Se 3 ppm, other components reduced to less than 30 ppm each Steel slabs having the above components were produced by continuous casting. This slab was heated at 1230 ° C. for 60 minutes and finished to a thickness of 2.2 mm by hot rolling. Hot-rolled sheet annealing was performed at 1050 ° C. for 60 seconds. Then, it was finished to a final thickness of 0.30 mm by cold rolling at a temperature of 130 ° C. Subsequently, recrystallization annealing was performed by changing the dew point at 25 vol% hydrogen, 76 vol% nitrogen, and 850 ° C, and changing the amount of decarburization after 60 seconds of soaking. After that, without applying an annealing separator, in a nitrogen atmosphere with a dew point of −20 ° C., heat up to 850 ° C. at 50 ° C./h. The final finish annealing was performed. After annealing, flattening annealing that also serves as decarburization in a wet hydrogen atmosphere at 900 ° C for 20 seconds, and then coating with a coating solution mixed with aluminum dichromate, emulsion resin, ethylene glycol and baking at 300 ° C did.
[0050]
Table 2 shows the magnetic properties of the product plate thus obtained in the rolling direction and in the direction perpendicular to the rolling direction. According to Table 2, using a material containing AlN and having reduced amounts of S and Se, the slab heating temperature should be 1200 ° C or higher, no annealing separator should be applied in final finish annealing, and before final finish annealing. the C content by ensuring 0.01～0.025Mass%, the magnetic flux density in the rolling direction is extremely high, the magnetic flux density B ₁ in a low magnetizing force perpendicular to the rolling direction is understood that more products 0.7T is obtained .
[0051]
[Table 2]

[0052]
Example 3
A steel slab composed of the components shown in Table 3 was heated to 1250 ° C. and finished to a thickness of 3.2 mm by hot rolling. The components not shown in Table 3 were all reduced to 50 ppm or less. Hot-rolled sheet annealing was performed at 1000 ° C. for 60 seconds. Thereafter, it was finished to a final thickness of 0.50 mm by cold rolling. Subsequently, recrystallization annealing was carried out at 940 ° C. for 20 seconds in a soaking atmosphere in an atmosphere of 75 vol% hydrogen, 25 vol% nitrogen, and dew point −25 ° C. Then, colloidal silica is applied as an annealing separator, heated to 10 ° C / h up to 850 ° C in a nitrogen atmosphere and held for 50 hours, then switched to a hydrogen atmosphere and heated up to 1050 ° C at a rate of 20 ° C / h. The final finish annealing was performed. Then, after flattening annealing at 875 ° C., an inorganic coating liquid mainly composed of aluminum dichromate was applied and baked at 250 ° C. to obtain a product.
[0053]
Table 3 shows the magnetic properties of the product plate thus obtained in the rolling direction and in the direction perpendicular to the rolling direction. According to Table 3, the magnetic flux density in the rolling direction is obtained by using a material containing AlN and reducing the amount of S and Se, setting the slab heating temperature to 1200 ° C. or higher, and not applying an annealing separator in the final finish annealing. very high magnetic flux density B ₁ in a low magnetizing force perpendicular to the rolling direction is understood that more products 0.7T is obtained.
[0054]
[Table 3]

[0055]
【The invention's effect】
According to the present invention, like the EI core, generator core or split motor core, emphasizing the magnetization characteristics in the rolling direction and the direction perpendicular to the rolling direction, and suitable for mass production of iron cores produced by punching It is possible to obtain a grain-oriented electrical steel sheet having a high magnetic flux density and having no forsterite coating.
[Brief description of the drawings]
FIG. 1 is a diagram showing the relationship between the amount of material S and the magnetic flux density in the rolling direction.
FIG. 2 is a diagram showing the relationship between the amount of material S and the magnetic flux density (B ₁ and B ₈ ) in the direction perpendicular to rolling.
FIG. 3 is a diagram showing the relationship between the amount of material S and the iron loss in the rolling direction.

Claims (3)

C: 0.08 mass% or less, Si: 1.0 mass% to 4.0 mass%, Mn: 0.005 to 3.0 mass%, sol.Al: 0.010 to 0.030 mass% and N: 30 to 100 massppm, S and Se are each 50 massppm have a reduced component composition below, a steel slab to a balance of Fe and unavoidable impurities ing, the hot-rolled sheet obtained by hot rolling after heating to 1200 ° C. or higher, one or intermediate When cold rolling is performed at least twice with annealing, followed by recrystallization annealing that also serves as decarburization, when final finishing annealing is performed without applying an MgO-based annealing separator , the final finishing annealing is 1000 ° C or less. The magnetic flux density B _{1 in the} direction perpendicular to the rolling is 0.7 T or more and mainly composed of forsterite, characterized in that the atmosphere has a nitrogen content of less than 50 vol% in the temperature range of 850 ° C. or higher. A method for producing a grain-oriented electrical steel sheet without an undercoat. The method for producing a grain-oriented electrical steel sheet according to claim 1, wherein the amount of C before the start of final finish annealing is controlled in a range of 0.010 to 0.025 mass%. Steel slabs are further added to Sb: 0.01 to 0.50 mass%, Sn: 0.01 to 0.50 mass%, Ni: 0.01 to 1.50 mass%, Cu: 0.01 to 0.50 mass%, P: 0.0005 to 0.50 mass%, and Cr: O.01. method for producing a grain-oriented electrical steel sheet according to claim 1 or 2 characterized by having a component composition comprising at least one compound selected from among ~1.50mass%.

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