JPH101722A - Production of grain oriented silicon steel sheet excellent in magnetic property - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase the magnetic flux density of a steel sheet and to reduce iron loss therein by prescribing an acid soluble Al content and an N content in a slab and coating it with a specified separation agent for annealing. SOLUTION: In the componental compsn. of a silicon steel stock as the object, 0.013 to 0.5wt.% acid soluble Al and 0.004 to 0.012% N are contained, and the ratio of Al/N is regulated to >=3.35. The acid soluble Al and N are required for forming an AlN inhibitor. In the production, after a cold rolled sheet having a final sheet thickness is obtd., decarburizing annealing and the application of a separation agent for annealing are executed, and then, finish annealing is executed. The separation agent for annealing performs important rolls of preventing fusion between steel sheets at the time of the finish annealing, controlling the behavior of the inhibitor components in the vicinity of the surface layer part of ferrite participating in the improvement of its magnetic properties in the process of the annealing and regulating the atmosphere between coil layers. For making better the effects, the separation agent for annealing in which, to 100 pts.wt. MgO, Ti compounds by 0.2 to 10 pts.wt. expressed in terms of Ti and 0.2 to 15 pts.wt. chloride are respectively added is used.

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 grain-oriented silicon steel sheet, and more particularly to a method for improving magnetic properties by devising a material component and an annealing separator composition.

[0002]

2. Description of the Related Art Grain-oriented silicon steel sheets are mainly used as iron core materials for transformers or rotating equipment, and are required to have high magnetic flux density and small iron loss as magnetic characteristics.

In order to obtain a grain-oriented silicon steel sheet having excellent magnetic properties, it is necessary to obtain a secondary recrystallized structure highly integrated in a {110} <001> orientation, a so-called Goss orientation. Therefore, in such a method for producing a grain-oriented silicon steel sheet, an inhibitor required for secondary recrystallization, such as MnS
After heating the directional silicon steel slab containing MnSe, MnSe, AlN, etc., and performing hot rolling, annealing is performed if necessary, and the final sheet is subjected to one or two or more cold rollings with intermediate annealing. It is common practice to increase the thickness and then perform decarburizing annealing, then apply an annealing separator containing MgO as a main component to the steel sheet, and then perform final finish annealing.

[0004] In the above-described grain-oriented silicon steel sheet containing AlN as an inhibitor component, it is known that the amount of acid-soluble Al and N greatly affects the secondary recrystallization and affects the magnetic properties of the obtained steel sheet. Have been. For this purpose, for example, JP-A-1-316421, JP-A-2-8328, JP-A-2-209426, JP-A-2-209
No. 427 and JP-A-2-243721,
The amount (%) of acid-soluble Al is {(27/14) × N (%) +0.0035}
It has been proposed to make ｛{(27/14) × N (%) + 0.0100}. Further, Japanese Patent Application Laid-Open No. 2-77524,
In JP-A-209428, JP-A-2-213419 and JP-A-2-243720, the amount (%) of the acid-soluble Al is expressed as {(27/14) × N (%) + 0.0030} to {(27 /14)
× N (%) + 0.0150 ° is proposed.

In such a proposed method, in any case, when the amount of acid-soluble Al is larger than the proposed formula, secondary recrystallization is incomplete, fine grains are generated, and magnetic properties are deteriorated. If the amount of acid-soluble Al is smaller than the proposed formula, the secondary recrystallization is stable, but the orientation is poor and it is difficult to obtain a good iron loss value. For this reason, in these methods, the amount of acid-soluble Al is limited to a predetermined range in relation to the amount of N, but the amount (%) of acid-soluble Al is ｛(27/14) × N (%) + 0 .0100｝, N
However, when the content is relatively large, even if the analysis value at the slab stage is within the limited range of the Al content, slight variations in the Al and N content depending on the analysis sampling position, or intermediate annealing Due to slight fluctuations in Al and N contents due to other intermediate steps such as temperature and decarburization annealing temperature, secondary recrystallization failure may partially occur and magnetic deterioration may occur. Was narrower.

On the other hand, a forsterite (Mg ₂ SiO ₄ ) -based insulating film is formed on the surface of the grain-oriented silicon steel sheet except for special cases. Since the properties of the forsterite coating affect the magnetic properties of the product, it is important to form a good forsterite coating.

Here, during the manufacturing process of the grain-oriented electrical steel sheet, the composition of the annealing separator applied to the steel sheet surface prior to the primary recrystallization annealing greatly affects the film formation and the secondary recrystallization process. Much research has been conducted on the influence of the magnetic properties of these materials, and improvements have been made.

For example, as an additive other than MgO incorporated in an annealing separator for the purpose of improving magnetic properties, Japanese Patent Publication No.
As disclosed in No. 14567, Cu, Sn,
A method of adding 0.01 to 15 parts by weight (as a metal element) of Ni, Co or a compound containing them, JP-A-60-243
TiO ₂ or TiO.
5 to 10 parts by weight and 0.1 to 5.0 parts by weight of SrS, SnS and CuS,
Or, in addition thereto, a method of adding 0.05 to 2.0 parts by weight of antimony nitrate, as disclosed in JP-A-61-79780, containing colloidal Sb or a compound containing Sb, or containing colloidal Sn or Sn. Methods for adding compounds are known.

Further, with respect to the improvement of the film properties, many techniques have been disclosed in which an annealing separator contains a Ti compound such as TiO ₂ in addition to MgO as a main component. For example, Shoko 5
In JP-A-1-12451, the content of Mg compound is 100 parts by weight.
By mixing the Ti compound in an amount of 2 to 40 parts by weight, Japanese Patent Publication No. 49-29049 discloses that 2 to 20 parts by weight of TiO ₂ is mixed with 100 parts by weight of heavy and low-active MgO. It is disclosed that the uniformity and the adhesion of the forsterite film are improved in any case. Furthermore, Japanese Patent Publication No. 56-15466 discloses TiO ₂ used as an annealing separator.
There is disclosed a technique for extinguishing black spot-like deposits made of a Ti compound by making fine particles into fine particles. Furthermore, Japanese Patent Publication No. 57-32716 proposes to mix a Sr compound in an amount of 0.1 to 10 parts by weight in terms of Sr as a method for forming a forsterite insulating film with good adhesion and excellent uniformity. ing.

[0010] However, in the case of a steel sheet using an AlN-based inhibitor, the material component to which the above-mentioned separating agent additive is applied is an acid-soluble Al which is conventionally known as described above in a range where secondary recrystallization is favorably generated. , N. Although improvements in film properties and magnetic properties were observed, it could not be said that the requirements for continuous improvements in film properties and magnetic properties were sufficiently satisfied.

Japanese Patent Application Laid-Open No. 7-188938 discloses a technique in which a Tl compound is blended into an annealing separator mainly composed of MgO for the purpose of obtaining giant crystal grains having a high magnetic flux density elongated in the sheet width direction. Have been. However, since the secondary grains were large, iron loss was slightly inferior to the obtained magnetic flux density.

On the other hand, as a method of improving the magnetic properties of a product, there is a method of obtaining a low iron loss by making a steel plate surface mirror-finished.
In this method of mirror-finishing the surface of a steel sheet, it is necessary to remove the forsterite insulating film usually formed on the surface of the grain-oriented silicon steel sheet. Techniques such as pickling have long been used as a removing method, and methods for smoothing the surface thereafter include chemical polishing and electrolytic polishing disclosed in JP-A-64-83620. However, removing the oxide film once formed and smoothing it further have problems such as difficulty in removing the oxide film (forsterite film) and poor productivity.

On the other hand, Al ₂ O ₃ disclosed in US Pat. No. 3,785,882 and JP-A No. 3785882 have been disclosed as a method of not forming an oxide film during finish annealing, instead of removing the oxide film once formed. There is a method using an annealing separator which does not react with SiO ₂ , such as a hydrated silicate mineral powder disclosed in JP-A-56-3414. This method is superior to the above-described method of removing the generated oxide film by pickling. However, in this method, oxides such as SiO ₂ generated during the decarburization annealing remain, so that a treatment such as chemical polishing or mechanical polishing was required to smooth the surface.

Further, chloride disclosed in JP-A-64-62417 and JP-A-2-228481 is added to an annealing separator to suppress the reaction between MgO and SiO ₂ during finish annealing. There is a way. Although this method is superior to the previous technology, the point that a thin oxide film remains and the obtained surface roughness is rougher than that obtained by using chemical polishing hinders the reduction of iron loss. In order to improve this, Japanese Patent Application Laid-Open
JP-346247A discloses a technique of adding a chloride of Bi, and reports that the surface smoothness is improved as compared with the conventional art, and the iron loss characteristics are improved.

However, in the case of an AlN-based inhibitor, the material component to which the above-mentioned mirror polishing technique is applied is an acid-soluble material which is well known in the art in a range where secondary recrystallization is favorably generated.
The range included Al and nitrogen.

[0016]

Conventionally, the present invention provides an acid-soluble Al content in a range such that secondary recrystallization is unstable and fine grains are easily generated or secondary recrystallization is poor.
Even if a material having an N content is used, secondary recrystallization can be favorably performed, and a high magnetic flux which cannot be obtained within the range of acid-soluble Al and N which has been disclosed as the optimum component range so far. It is an object of the present invention to propose a method capable of producing a product having a high density and low iron loss.

Another object of the present invention is to provide an acid-soluble Al content in a range in which secondary recrystallization is unstable and fine particles are easily generated or secondary recrystallization is poor. N
Even if the amount of material is used, it is possible to remove the oxide film on the surface of the steel sheet during finish annealing, and to smooth the steel sheet surface for good secondary recrystallization to produce a product with a further low iron loss. It is to propose.

[0018]

In producing a grain-oriented silicon steel sheet, an annealing separator has an effect of preventing fusion between the steel sheets at the time of finish annealing, and has an effect of improving magnetic properties during finish annealing. In addition to playing an important role in controlling the behavior of the inhibitor component in the vicinity of the iron surface layer and controlling the atmosphere between the coil layers, the finish annealing forms a forsterite film on the steel sheet surface.

In consideration of the characteristics of the annealing separator, the inventors have determined that the values of the acid-soluble Al and N of the raw material component can be conventionally determined if the secondary recrystallization is complete and good magnetic characteristics can be obtained. Without limiting to the reported range, as a result of repeated experiments with MgO as the main component and various sub-components added and mixed, secondary recrystallization was unstable and fine grains were generated conventionally. It has been found that when a material having an acid-soluble Al or N content within a range that easily or almost completely causes secondary recrystallization failure is used, and the Tl compound is reduced into the annealing separator, the magnetic properties are significantly improved. .

It has also been found that the coexistence of a Bi compound in the annealing separator further improves the magnetic properties.

Further, by coexisting the Tl compound and chloride in the annealing separator, the surface of the steel sheet after finish annealing is smoothened like a mirror surface more than simply adding chloride, and the magnetic properties are greatly improved. I found to do.

That is, the gist of the present invention is as follows. (1) Acid-soluble Al: 0.013 to 0.05 wt% and N: 0.004 to 0.
Slab for oriented silicon steel sheet containing 012 wt% is hot-rolled, then cold-rolled once or twice or more with intermediate annealing, then decarburized annealing, and then mainly MgO In a method for producing a grain-oriented silicon steel sheet comprising a series of steps of applying an annealing separator and then performing a final finish annealing, the acid-soluble Al (wt.
%) ≧ 3.35 × N (wt%), and as the annealing separator, the Tl compound is 0.2 to 10 in terms of Tl based on 100 parts by weight of MgO.
A method for producing a grain-oriented silicon steel sheet having excellent magnetic properties, characterized by applying an annealing separator added in parts by weight (first invention)

(2) In the first invention, the annealing separator is Mg.
A method for producing a grain-oriented silicon steel sheet having excellent magnetic properties, wherein 0.2 to 10 parts by weight of a Tl compound and 0.2 to 15 parts by weight of a chloride are added to 100 parts by weight of O, respectively. ).

(3) In the first or second invention, the annealing separator is obtained by adding 0.2 to 10 parts by weight, in terms of Bi, of a Bi compound to 100 parts by weight of MgO. A method for producing a silicon nitride steel sheet (third invention).

[0025]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention will be described below based on experimental results. (Experiment 1) C: 0.073 wt%, Si: 3.30 wt%, sol.Al:
0.032 wt%, N: 0.0080 wt%, (sol.Al/N=4.0),
A directional silicon steel slab containing 0.069 wt% of Mn, 0.020 wt% of Se, and 0.025 wt% of Sb, with the balance being substantially Fe, is hot-rolled and then cold-rolled to a final Set the thickness to 0.
The cold-rolled sheet which was 23 mm, at 840 ° C. at H ₂ -H ₂ ON ₂ atmosphere 12
Decarburization annealing for 0 seconds was performed. Then, to MgO shown in Table 1,
Annealing separator containing 6% TiO ₂ (Condition No. 1), MgO-based annealing separator containing Tl compound (Conditions No. 2 to 6)
And a MgO-based annealing separator containing Tl compound and Bi compound (Condition Nos. 7 to 10) is applied as a slurry and dried, and the final finish annealing is held at 850 ° C for 20 hours in a nitrogen atmosphere. Followed by 75 vol% hydrogen and 25 vol% nitrogen
In the atmosphere of 15 ° C./hr at a heating rate of 1150 ° C., and then in a hydrogen atmosphere of 1200 ° C. for 5 seconds.
Time purification annealing was performed. Thereafter, a coating containing magnesium phosphate and colloidal silica as main components was applied.

The magnetic field of the product thus obtained is 800 A /
The magnetic flux density (B ₈ value) at 1.7 m and the iron loss (W _17/50 value) at 1.7 T and 50 Hz were measured. Table 1 shows the measurement results.
Are also shown.

[0027]

[Table 1]

In Table 1, conditions Nos. 2 to 10 are conditions in which an MgO-based annealing separator containing a proper amount of a Tl compound or a Tl compound and a Bi compound is used as an applicable example of the present invention. It can be seen that low iron loss characteristics are obtained. Further, it can be seen that better magnetic properties can be obtained by using the Tl compound and the Bi compound together than by using the Tl compound alone. On the other hand, condition No. 1 was a comparative example in which the Tl compound was not added, but had poor secondary recrystallization.

FIG. 1 shows condition No. 1 and FIG. 2 shows condition No. 2
Each shows a metallographic photograph of the steel sheet after the secondary recrystallization treatment, to which is applied. As can be seen from these drawings, the condition N
o. In the case of 1, there is almost no secondary recrystallization,
Under condition 2, secondary recrystallization has occurred, and the secondary recrystallized grains are relatively small and are not excessively coarse.

(Experiment 2) C: 0.073 wt%, Si: 3.30 wt
%, Sol.Al: 0.025 wt%, N: 0.0085 wt%, (sol.Al/
N = 2.94), Mn: 0.069 wt%, Se: 0.020 wt%, Sb: 0.
A hot rolled oriented silicon steel slab containing 025 wt%, with the balance substantially consisting of Fe, then cold rolled into a cold rolled sheet with a final sheet thickness of 0.23 mm, H ₂ − Decarburization annealing was performed at 840 ° C. for 120 seconds in an H ₂ ON ₂ atmosphere. Then, Table 2
Annealing separator containing a combination of TiO ₂ 6% to Shimesuru MgO (the condition N
o. 1) An annealing separator mainly composed of MgO to which a Tl compound is added (N
o. 2-6) and MgO to which Tl compound and Bi compound are added
After the main annealing separator (conditions Nos. 7 to 10) is applied as a slurry and dried, the final finish annealing is maintained at 850 ° C. for 20 hours in a nitrogen atmosphere, followed by 75 vol% hydrogen and 25 vol nitrogen. %, The temperature was raised to 1150.degree. C. at a rate of 15.degree. C./hr, followed by annealing for purification for 5 hours in a hydrogen atmosphere at 1200.degree. Thereafter, a coating containing magnesium phosphate and colloidal silica as main components was applied. The magnetic field of the product thus obtained is 80
The magnetic flux density at 0 A / m (B ₈ value) and the iron loss at 1.7 T, 50 Hz (W _17/50 value) were measured. These measurement results are also shown in Table 2.

[0031]

[Table 2]

In Table 2, conditions Nos. 2 to 10 use MgO-based annealing separators containing a proper amount of a Tl compound or a Tl compound and a Bi compound, but the magnetic flux density is improved as compared with the condition 1. However, it can be seen that iron loss may increase. FIG. 3 shows a metallographic photograph of the steel sheet after the secondary recrystallization treatment to which the condition No. 1 and the condition No. 2 are applied, respectively. As can be seen from these drawings, condition No. 1
In the condition of condition No. 2, very coarse secondary recrystallized grains are obtained, while the form of the secondary recrystallized grains is almost normally obtained. Therefore, it is considered that there was a case where the iron loss did not decrease in the condition Nos. 2 to 10 as compared with the improvement of the magnetic flux density.

(Experiment 3) C: 0.065 wt%, Si: 3.35 wt
%, Mn: 0.072 wt%, Se: 0.018 wt%, Sb: 0.026 wt%
%, Sol.Al: 0.01 to 0.05 wt%, N: 0.004 to 0.012 wt%
Containing, the remainder is hot-rolled a number of grain-oriented silicon steel slabs substantially composed of Fe, then cold-rolled into a cold-rolled sheet having a final sheet thickness of 0.23 mm, H ₂ -H ₂ ON _{2 In an} atmosphere
Decarburization annealing was performed at 840 ° C for 120 seconds. Then, Ti is added to MgO.
A slurry of an annealing separator containing 6% of O ₂ and 3 parts by weight of Tl ₂ SO ₄ was applied as a slurry and dried.
Hold at 0 ° C for 20 hours in a nitrogen atmosphere.
vol. and 25 vol.% nitrogen, a secondary recrystallization annealing was performed in which the temperature was raised to 1150 ° C at a rate of 15 ° C / hr.
Purification annealing was performed in a hydrogen atmosphere at 00 ° C. for 5 hours. Then, after applying a coating containing magnesium phosphate and colloidal silica as main components, the magnetic flux density (B ₈ value) and iron loss (W _17/50 value) of the obtained product were measured.

The acid-soluble Al and N contents of the slab and B
FIG. 5 shows the relationship between the ₈ values: W _17/50 value. Straight line ab (sol.
It can be seen that high magnetic flux density and low iron loss are obtained on the side where the sol.Al (%) / N (%) ratio is higher than that of (Al / N = 3.35).

(Experiment 4) C: 0.071 wt%, Si: 3.34 wt
%, Mn: 0.069 wt%, Se: 0.019 wt%, Sb: 0.025 wt%
%, Cu: 0.10 wt%, sol. Al: 0.01-0.05 wt%, N: 0.00
A number of directional silicon steel slabs containing 4 to 0.012 wt%, with the balance being substantially Fe, are hot-rolled and then cold-rolled into cold-rolled sheets with a final thickness of 0.23 mm. , H ₂ -H
Decarburization annealing was performed at 840 ° C. for 120 seconds in a ₂ ON ₂ atmosphere. Then, 6% of TiO ₂ and 3 parts by weight of Tl ₂ SO ₄ were added to MgO,
_After applying and drying an annealing separator containing 3 parts by weight of ₂ O ₃ as a slurry, final finishing annealing is maintained at 850 ° C. for 20 hours in a nitrogen atmosphere, followed by 75 vol% of hydrogen,
1150 ° C at a rate of 15 ° C / hr in an atmosphere of 25 vol% nitrogen
Secondary recrystallization annealing was performed, followed by annealing for 5 hours in a hydrogen atmosphere at 1200 ° C. Then, after applying a coating mainly composed of magnesium phosphate and colloidal silica, the magnetic flux density of the obtained product (B ₈ value)
And iron loss (W _17/50 value).

FIG. 6 shows the relationship between the acid-soluble Al and N contents of the slab and the B ₈ value and W _17/50 value. From the figure, the straight line a
b (sol. Al (%) / N (%) = 3.35)
It can be seen that high magnetic flux density and low iron loss are obtained on the side where the (%) / N (%) ratio is high.

From the above experiments, acid-soluble Al (sol.Al) was
After hot rolling a slab for grain-oriented silicon steel sheet containing 0.013 to 0.05 wt% and N of 0.004 to 0.012 wt%, it is subjected to one or two cold rollings with intermediate annealing, followed by decarburization annealing. After that, an annealing separator mainly composed of MgO is applied, and then a final finish annealing is performed. In a method for producing a grain-oriented silicon steel sheet, N and acid-soluble Al contained in the slab are subjected to acid treatment. Soluble Al (wt%) ≧ 3.35 × N (wt%)
And, in the step of applying the annealing separator, Mg
By adding and adding 0.2 to 10 parts by weight of a Tl compound in terms of Tl, and more preferably 0.2 to 10 parts by weight of a Bi compound in terms of Bi with respect to 100 parts by weight of O, extremely high magnetic flux density and low It was found that a grain-oriented silicon steel sheet having a forsterite coating with iron loss can be manufactured.

Next, an experiment was conducted in which chloride was added to the annealing separator. (Experiment 5) C: 0.068 wt%, Si: 3.25 wt%, sol.Al:
0.035 wt%, N: 0.0090 wt%, (sol. Al / N = 3.89),
Mn: 0.072 wt%, Se: 0.016 wt%, Sb: 0.025 wt% and
Cu: 0.10 wt%, the remainder is hot rolled directional silicon steel slab substantially composed of Fe, then cold rolled into a cold rolled sheet with a final thickness of 0.23 mm, Decarburization annealing was performed at 840 ° C. for 120 seconds in an H ₂ -H ₂ ON ₂ atmosphere. afterwards,
As shown in Table 3, MgO simple annealing separator (condition No. 1), MgO
Separating agent with chloride added to (Condition No. 2-5) and
Annealing separating agent (addition of Tl compound and chloride to MgO)
Nos. 6 to 10), an annealing separator (conditions Nos. 11 to 15) in which a Tl compound, a chloride and a Bi compound were added to MgO was applied as a slurry and dried, and the final finish annealing was performed with 25% N _The temperature was raised to 1200 ° C. at a heating rate of 15 ° C./hr in an H ₂ gas stream containing _2, and the operation was performed at 1200 ° C. for 5 hours in an H ₂ atmosphere. Thereafter, the surface of the steel sheet was washed with water and the surface state was observed. The results are shown in Table 3.

[0039]

[Table 3]

In Table 3, under condition No. 1, a normal oxide film (forsterite film) was formed. No. 2
In No. 5, a thin oxide film remained even when chloride was added to the annealing separator. On the other hand, the condition using an annealing separator in which chloride and a Tl compound or a Tl compound and a Bi compound coexist was used.
In Nos. 6 to 15, the steel plate surface was mirror-finished. As shown in Table 3, the results of the measurement of the magnetic properties after strain relief annealing of the samples of Condition Nos. 6 to 15 are shown, and it can be seen that a value of low iron loss was obtained at an extremely high magnetic flux density. Note that condition N
o. No values were given for all of the samples 1 to 5 because of poor secondary recrystallization.

(Experiment 6) C: 0.070 wt%, Si: 3.37 wt%
%, Mn: 0.069 wt%, Se: 0.019 wt%, Sb: 0.026 wt%
%, Sol.Al: 0.01 to 0.05 wt%, N: 0.004 to 0.012 wt%
Containing, the remainder is hot-rolled a number of grain-oriented silicon steel slabs substantially composed of Fe, then cold-rolled into a cold-rolled sheet having a final sheet thickness of 0.23 mm, H ₂ -H ₂ ON _{2 In an} atmosphere
Decarburization annealing was performed at 840 ° C for 120 seconds. Then, Tl is added to MgO
An annealing separator containing 3 parts by weight of ₂ O ₃ and ₂ parts by weight of CaCl ₂ was applied as a slurry and dried, and then the final finish annealing was maintained at 850 ° C. for 20 hours in a nitrogen atmosphere. In the atmosphere of 25% vol% and 25% nitrogen, a secondary recrystallization annealing was performed at a heating rate of 20 ° C / hr to 1150 ° C, followed by a purification annealing for 5 hours in a hydrogen atmosphere at 1200 ° C. .
Then, after applying a coating containing magnesium phosphate and colloidal silica as main components, the magnetic flux density (B ₈ value) and iron loss (W _17/50 value) of the obtained product were measured.

The acid-soluble Al and N contents of the slab and B
FIG. 7 shows the relationship between the ₈ values: W _17/50 value. Straight line ab (sol.
It can be seen that high magnetic flux density and low iron loss are obtained on the side where the sol.Al (%) / N (%) ratio is higher than that of (Al / N = 3.35).

(Experiment 7) C: 0.071 wt%, Si: 3.34 wt
%, Mn: 0.069 wt%, Se: 0.019 wt%, Sb: 0.025 wt%
%, Cu: 0.10 wt%, sol. Al: 0.01-0.05 wt%, N: 0.00
A number of directional silicon steel slabs containing 4 to 0.012 wt%, with the balance being substantially Fe, are hot-rolled and then cold-rolled into cold-rolled sheets with a final thickness of 0.23 mm. , H ₂ -H
Decarburization annealing was performed at 840 ° C. for 120 seconds in a ₂ ON ₂ atmosphere. Thereafter, 3 parts by weight of Tl ₂ SO ₄ , 3 parts by weight of Bi ₂ O _3, and 3 parts by weight of MgCl ₂ were added to MgO, and an annealing separator mixed with each was applied as a slurry and dried, and then the final finish annealing was performed.
Hold at 850 ° C. for 20 hours in a nitrogen atmosphere, and then perform a secondary recrystallization annealing to anneal to 1150 ° C. at a rate of 15 ° C./hr in an atmosphere of 75 vol% hydrogen and 25 vol% nitrogen, Subsequently, purification annealing was performed in a hydrogen atmosphere at 1200 ° C. for 5 hours. Then, after applying a coating containing magnesium phosphate and colloidal silica as main components, the magnetic flux density (B ₈ value) and iron loss (W _17/50 value) of the obtained product were measured.

FIG. 8 shows the relationship between the acid-soluble Al and N contents of the slab and the B ₈ value and W _17/50 value. From the figure, the straight line a
b (sol. Al (%) / N (%) = 3.35)
It can be seen that high magnetic flux density and low iron loss are obtained on the side where the (%) / N (%) ratio is high.

From the above experiments, acid-soluble Al (sol.
After hot rolling a slab for a grain oriented silicon steel sheet containing 0.013 to 0.05 wt% and nitrogen of 0.004 to 0.012 wt%, it is subjected to one or two or more cold rollings with intermediate annealing, and then decarburizing annealing After applying an annealing separator mainly composed of MgO, a method for producing a grain-oriented silicon steel sheet comprising a series of steps of applying a final finish annealing is carried out in an acid-soluble Al (%) ≧ 3.
35 × Nitrogen (%), and in the step of applying the annealing separator, the Tl compound was converted to 0.2 to 10 in terms of Tl based on 100 parts by weight of MgO.
Parts by weight and 0.2 to 15 parts by weight of chloride, further if necessary
By adding the Bi compound in an amount of 0.2 to 10 parts by weight in terms of Bi, and applying the annealing separator, the steel sheet surface after finish annealing is smoothened like a mirror surface. It was found that a loss-oriented silicon steel sheet could be manufactured.

Regarding the composition of the silicon steel material to which the present invention is applied, acid-soluble Al (sol.
wt% and N in the ratio of 0.004 to 0.012 wt% (sol.Al
(%) / N (%)) is 3.35 or more.

Acid soluble Al (sol. Al) and N are required to form AlN inhibitors. The amount of Al is determined according to the amount of N. In the present invention, “Sol. Al (%) / N
(%) ”Is 3.35 or more. If the N content is too small, the amount of the AlN inhibitor is insufficient, and if the N content is too large, surface defects called blisters occur frequently in the product. Therefore, the content of N is set in the range of 0.004 to 0.012 wt%.

In addition to the above-mentioned Al content and N content, those in the range usually used as a grain-oriented silicon steel sheet can be used. For example, C: 0.02 to 0.10 wt%, Si: 2.0 to 4.
5 wt%, Mn: 0.02 to 0.20 wt%, and at least one of S and Se alone or in a total amount of 0.010 to 0.040 wt%
% Is preferred. In addition, if necessary, Sb0.01
~ 0.20wt%, Cu: 0.02 ~ 0.20wt%, Mo: 0.01 ~ 0.05wt
%, Sn: 0.02 to 0.30 wt%, Ge: 0.02 to 0.30 wt%, Ni: 0.
01 to 0.20 wt%.

C is a component necessary for improving the crystal structure by utilizing the α-γ transformation at the time of hot rolling.
%, A good primary recrystallized structure cannot be obtained.
If it exceeds 0.10 wt%, decarburization becomes difficult, decarburization becomes poor, and magnetic properties deteriorate, so that about 0.02 to 0.10 wt% is preferable.

Si is a component necessary to increase the electrical resistance of the product and reduce the eddy current loss. If the content is less than 2.0 wt%, the crystal orientation is impaired by α-γ transformation during final finish annealing, If it exceeds 4.5 wt%, there is a problem with cold rolling.
2.0 to 4.5 wt% is preferred.

Mn and Se and / or S function as an inhibitor. If the amount of Mn is less than 0.02% or the amount of S or Se alone or the total amount is less than 0.010% by weight, the inhibitor function is insufficient. On the other hand, if the amount of Mn exceeds 0.20 wt% or the amount of S or Se alone or the total amount exceeds 0.040 wt%, the temperature required for slab heating becomes too high and is not practical, so that Mn is 0.02 to 0.20%. It is preferable that wt% and S or Se be used alone or in a total amount of 0.010 to 0.040 wt%.

Further, in order to improve the magnetic flux density, Sb,
Cu, Ge, and Ni can be added. Sb is 0.20%
When the content exceeds 0.01%, the decarburization property becomes poor, and when the content is less than 0.01% by weight, there is no effect. If the content of Cu exceeds 0.20 wt%, the pickling property deteriorates, and if it is less than 0.01 wt%, there is no effect, so 0.01 to 0.20 wt% is preferable. If the content of Sn and germanium exceeds 0.30 wt%, a good primary recrystallization structure cannot be obtained, and if the content is less than 0.02 wt%, there is no effect, so 0.02 to 0.30% is preferable. If Ni exceeds 0.20 wt%, the hot strength decreases, and
If the content is less than 01 wt%, there is no effect, so 0.01 to 0.20 wt% is preferable.

Mo can be added to improve the surface properties. If the Mo content exceeds 0.05 wt%, the decarburization property will deteriorate,
If the amount is less than 0.01 wt%, there is no effect, so 0.01 to 0.05 wt% is preferable.

In the manufacturing process of the grain-oriented silicon steel sheet, which is the object of the present invention, molten steel obtained by a conventionally used steelmaking method is cast by a continuous casting method or an ingot casting method, and divided if necessary. Obtain a slab across the block rolling process, then hot-roll, and if necessary, perform hot-rolled sheet annealing, and then cold roll the final sheet thickness once or twice or more with intermediate annealing Obtain a cold rolled sheet.

Next, decarburizing annealing and application of an annealing separator are performed. The latter uses an annealing separator in which a Tl compound is added in an amount of 0.2 to 10 parts by weight in terms of Tl under the conditions according to the invention described above. . Also, this annealing separator is made of MgO 10
0 to 10 parts by weight of the Tl compound and 0.2 to 15 parts by weight of chloride, and 0.2 to 15 parts by weight of chloride may be added to the annealing separator, and the Tl compound may be added to 100 parts by weight of MgO.
0.2 to 10 parts by weight in terms of Tl, 0.2 to 10 parts in terms of Bi in Bi compound
Parts by weight, 0.2 to 10 parts by weight of a Tl compound and 100 parts by weight of MgO per 100 parts by weight of the added annealing separator and MgO.
An annealing separator may be added in which 0.2 to 15 parts by weight of the Bi compound and 0.2 to 10 parts by weight of the Bi compound in terms of Bi are added.

The Tl compound was converted to 100 parts by weight of MgO in terms of Tl.
When the amount is less than 0.2 part by weight, the effect of improving magnetism is not obtained. On the other hand, when the amount exceeds 10 parts by weight, the effect of improving magnetism cannot be obtained even if the added amount is further increased. Chloride
If the amount is less than 0.2 parts by weight with respect to 100 parts by weight of MgO, the effect of using a Tl compound together to make the steel sheet mirror-like is remarkable, while 15
If the amount exceeds part by weight, the surface roughness of the steel sheet after finish annealing becomes rather coarse, so the above range is limited. If the Bi compound is less than 0.2 parts by weight of MgO in terms of Bi, the effect of improving the magnetism is small if it is less than 0.2 parts by weight, while if it exceeds 10 parts by weight, the effect of improving the magnetism cannot be obtained even if the added amount is further increased. Limited to.

As the Tl compound in the present invention, for example, Tl ₂ SO ₄ , Tl ₂ O ₃ , TlNO _{3 and the} like, and as the Bi compound,
Bi ₂ O ₃ , Bi ₂ S ₃ , Bi ₂ (NO ₃ ) ₃ , Bi ₂ (SO ₄ ) _{3 and the} like, and chlorides such as MgCl ₂ , CaCl ₂ and KCl can be used.

It is to be noted that MgO, which is a main component of the annealing separator, may be a normal product, and may further contain other TiO ₂ or Sr compound or the like in order to improve magnetic properties and coating properties.

Thereafter, secondary recrystallization annealing and purification annealing are performed at 1000 to 1200 ° C. for about 3 to 50 hours to obtain a product sheet. Thereafter, it is advantageous to apply a further phosphate-based insulating coating, preferably an insulating coating that imparts tension. Performing a known magnetic domain refining treatment after final cold rolling, final finish annealing, or after insulation coating is effective for further reducing iron loss.

[0060]

【Example】

(Example 1) C: 0.075 wt%, Si: 3.41 wt%, Mn: 0.06
7 wt%, Se: 0.019 wt%, sol. Al: 0.035 wt%, N: 0.
A silicon steel slab containing 095 wt%, (sol.Al/N = 3.68), Sb: 0.027 wt% and the balance substantially consisting of Fe was heated at 1430 ° C for 30 minutes, and then hot-rolled. 2.2 thickness
mm hot rolled sheet. Next, after subjecting the hot-rolled sheet to annealing at 1000 ° C. for 1 minute, the sheet was cold-rolled to a thickness of 1.5 mm, and further 1100
After performing intermediate annealing at 2 ° C. for 2 minutes, cold rolling was performed to finish to a final thickness of 0.23 mm. Then, decarburization annealing was performed at 840 ° C. for 2 minutes in an H ₂ —H ₂ ON ₂ atmosphere. Then, Table 4
After applying an annealing separator of the composition shown in
Hold at 0 ° C for 20 hours in a nitrogen atmosphere.
A second recrystallization annealing is performed in an atmosphere of 75 vol% and nitrogen at 25 vol% at a heating rate of 20 ° C / hr to 1150 ° C, followed by annealing.
Purification annealing was performed in a hydrogen atmosphere at 1200 ° C. for 5 hours. Thereafter, a coating containing magnesium phosphate and colloidal silica as main components was applied.

The magnetic flux density (B ₈ value) at a magnetic field of 800 A / m and the iron loss at 1.7 T and 50 Hz (W _17/50 value) of the obtained product were investigated. Table 4 also shows these results. It can be seen that a product having good magnetic properties was obtained under the conditions according to the present invention.

[0062]

[Table 4]

Example 2 C: 0.066 wt%, Si: 3.27 wt
%, Mn: 0.068 wt%, Se: 0.021 wt%, sol.Al: 0.026
wt%, N: 0.075 wt%, (sol. Al / N = 3.47), Sb: 0.
A silicon steel slab containing 025 wt% and Cu: 0.10 wt%, with the balance substantially consisting of Fe, was heated at 1430 ° C. for 30 minutes, hot-rolled, and then cold-rolled to obtain a final sheet. Thickness 0.
Finished to 23mm. Then 840 in H ₂ -H ₂ ON ₂ atmosphere
Decarburization annealing for 2 minutes at ℃. Thereafter, an annealing separator having the composition shown in Table 5 was applied to the surface of the steel sheet.
Hold for 20 hours in a nitrogen atmosphere, followed by 65 vol hydrogen
% And an atmosphere of 35 vol% nitrogen at a heating rate of 15 ° C / hr
Perform secondary recrystallization annealing to raise the temperature to 50 ° C, then 1200 ° C
For 5 hours in a hydrogen atmosphere. After this,
A coating mainly composed of magnesium phosphate and colloidal silica was applied.

The product thus obtained was subjected to the same investigation as in Example 1. Table 5 also shows the results. It can be seen that a product having good magnetic properties was obtained under the conditions according to the present invention.

[0065]

[Table 5]

Example 3 C: 0.076 wt%, Si: 3.39 wt
%, Mn: 0.071 wt%, Se: 0.020 wt%, sol.Al: 0.023
wt%, N: 0.065 wt%, (sol. Al / N = 3.54), Sb: 0.
A silicon steel slab containing 025 wt% and Cu: 0.10 wt%, with the balance substantially consisting of Fe, was heated at 1430 ° C. for 30 minutes, hot-rolled, and then cold-rolled. Board thickness
Finished to 0.23mm. Thereafter, grooves having a width of 150 μm and a depth of 20 μm were introduced in the thickness direction of the steel sheet at intervals of 3 mm in the longitudinal direction of the steel sheet by a known etching method to perform magnetic domain refining treatment. Then, decarburization annealing was performed at 840 ° C. for 2 minutes in an H ₂ —H ₂ ON ₂ atmosphere. Thereafter, an annealing separator having the composition shown in Table 6 was applied to the surface of the steel sheet, held at 850 ° C. for 20 hours in a nitrogen atmosphere, and subsequently kept at 15 ° C. in an atmosphere of 80 vol% hydrogen and 20 vol% nitrogen. The secondary recrystallization annealing was performed by raising the temperature to 1150 ° C. at a heating rate of / hr, and then the purification annealing was performed in a hydrogen atmosphere at 1200 ° C. for 5 hours. Thereafter, a coating containing magnesium phosphate and colloidal silica as main components was applied.

The same investigation as in Example 1 was conducted on the product thus obtained. The results are shown in Table 6. It can be seen that a product having good magnetic properties was obtained under the conditions according to the present invention.

[0068]

[Table 6]

Example 4 C: 0.075 wt%, Si: 3.41 wt
%, Mn: 0.067 wt%, Se: 0.019 wt%, sol.Al: 0.035
wt%, N: 0.095 wt%, (sol. Al / N = 3.68), Sb: 0.
A silicon steel slab containing 027 wt% and the balance substantially consisting of Fe was heated at 1430 ° C. for 30 minutes, and then subjected to hot rolling to obtain a hot-rolled sheet having a sheet thickness of 2.2 mm. Next, after subjecting the hot-rolled sheet annealing to 1000 ° C. for 1 minute, the sheet thickness was reduced to 1.5 mm by cold rolling.
Further, after intermediate annealing at 1100 ° C. for 2 minutes, cold rolling was performed to finish to a final thickness of 0.23 mm. Then, decarburization annealing was performed at 840 ° C. for 2 minutes in an H ₂ —H ₂ ON ₂ atmosphere. Thereafter, an annealing separator having the composition shown in Table 7 was applied to the surface of the steel sheet, and kept at 850 ° C. for 20 hours in a nitrogen atmosphere. Subsequently, the steel was kept at 20 ° C. in an atmosphere of 75 vol% hydrogen and 25 vol% nitrogen. / hr
Was carried out at a heating rate of 1150 ° C., followed by purifying annealing in a hydrogen atmosphere at 1200 ° C. for 5 hours. Thereafter, a coating containing magnesium phosphate and colloidal silica as main components was applied.

The magnetic flux density (B ₈ value) at a magnetic field of 800 A / m and the iron loss at 1.7 T and 50 Hz (W _17/50 value) of the product thus obtained were investigated. Table 7 also shows these results. It can be seen that a product having good magnetic properties was obtained under the conditions according to the present invention.

[0071]

[Table 7]

Example 5 C: 0.066 wt%, Si: 3.27 wt%
%, Mn: 0.068 wt%, Se: 0.021 wt%, sol.Al: 0.026
wt%, N: 0.075 wt%, (sol. Al / N = 3.47), Sb: 0.
A silicon steel slab containing 025 wt% and Cu: 0.10 wt%, with the balance substantially consisting of Fe, was heated at 1430 ° C. for 30 minutes, hot-rolled, and then cold-rolled to obtain a final sheet. Thickness 0.
Finished to 23mm. Then 840 in H ₂ -H ₂ ON ₂ atmosphere
Decarburization annealing for 2 minutes at ℃. Thereafter, an annealing separator having the composition shown in Table 8 was applied to the surface of the steel sheet.
Hold for 20 hours in a nitrogen atmosphere, followed by 65 vol hydrogen
% And an atmosphere of 35 vol% nitrogen at a heating rate of 15 ° C / hr
Perform secondary recrystallization annealing to raise the temperature to 50 ° C, then 1200 ° C
For 5 hours in a hydrogen atmosphere. After this,
A coating mainly composed of magnesium phosphate and colloidal silica was applied.

The product thus obtained was subjected to the same investigation as in Example 4. Table 8 also shows the results. It can be seen that a product having good magnetic properties was obtained under the conditions according to the present invention.

[0074]

[Table 8]

(Example 6) C: 0.076 wt%, Si: 3.39 wt
%, Mn: 0.071 wt%, Se: 0.020 wt%, sol.Al: 0.023
wt%, N: 0.065 wt%, (sol. Al / N = 3.54), Sb: 0.
A silicon steel slab containing 025 wt%, Cu: 0.1 and the balance substantially consisting of Fe is heated at 1430 ° C. for 30 minutes, subjected to hot rolling, and then subjected to cold rolling to obtain a final thickness. Finished to 0.23mm. After that, a groove having a width of 150 μm and a depth of 20 μm is formed in the longitudinal direction of the steel sheet by a known etching method.
It was introduced at an interval of mm, and a magnetic domain refining treatment was performed. Then H ₂ -H
Decarburization annealing was performed at 840 ° C. for 2 minutes in a ₂ ON ₂ atmosphere. Thereafter, an annealing separator having the composition shown in Table 9 was applied to the surface of the steel sheet, held at 850 ° C. for 20 hours in a nitrogen atmosphere, and subsequently heated at 15 ° C. in an atmosphere of 80 vol% hydrogen and 20 vol% nitrogen. The secondary recrystallization annealing was performed by raising the temperature to 1150 ° C. at a heating rate of / hr, and then the purification annealing was performed in a hydrogen atmosphere at 1200 ° C. for 5 hours. Thereafter, a coating containing magnesium phosphate and colloidal silica as main components was applied.

The same investigation as in Example 4 was conducted on the product thus obtained. Table 9 also shows the results. It can be seen that a product having good magnetic properties was obtained under the conditions according to the present invention.

[0077]

[Table 9]

[0078]

According to the present invention, it is possible to stably produce a grain-oriented silicon steel sheet having extremely excellent magnetic properties by using a material having a component which has conventionally failed secondary recrystallization. . In addition, when using an annealing separator containing chloride, the oriented silicon steel sheet has a much higher magnetic flux density and lower iron loss than the conventional steel sheet, in which the steel sheet surface after finish annealing is smoothened like a mirror. Can be easily manufactured.

[Brief description of the drawings]

FIG. 1 is a photograph of a metal structure after finish annealing when an annealing separator containing no Tl compound is used.

FIG. 2 is a microstructure photograph showing secondary recrystallized grains after finish annealing when an annealing separator containing 3 parts by weight of Tl ₂ SO ₄ is used.

FIG. 3 is a metallographic photograph showing secondary recrystallized grains after finish annealing in the case where an annealing separator containing no Tl compound is used.

FIG. 4 is a metallographic photograph showing secondary recrystallized grains after finish annealing when an annealing separator containing 3 parts by weight of Tl ₂ O ₃ is used.

FIG. 5 is a graph showing the relationship between the nitrogen content and acid-soluble Al content of a slab and the magnetic properties of a product when a Tl compound is added to an annealing separator.

FIG. 6 is a graph showing the relationship between the nitrogen content and acid-soluble Al content of a slab and the magnetic properties of a product when a Tl compound and a Bi compound are added to an annealing separator.

FIG. 7 is a graph showing the relationship between the nitrogen content and acid-soluble Al content of a slab and the magnetic properties of a product when a Tl compound and a chloride are added to an annealing separator.

FIG. 8 is a graph showing the relationship between the nitrogen content and acid-soluble Al content of a slab and the magnetic properties of a product when a Tl compound, a Bi compound, and a chloride are added to an annealing separator.

Claims (3)

[Claims] 1. An acid-soluble Al: 0.013 to 0.05 wt% and N:
A slab for grain-oriented silicon steel containing 0.004 to 0.012 wt% is hot-rolled, cold-rolled once or twice or more with intermediate annealing, then decarburized annealing, and then mainly MgO. A method for producing a grain-oriented silicon steel sheet, comprising a series of steps of applying an annealing separating agent to be subjected to final finish annealing, wherein acid-soluble Al (wt%) ≧ 3.35 × N (wt%), and as the annealing separator, a Tl compound was added to Tg
A method for producing a grain-oriented silicon steel sheet having excellent magnetic properties, characterized by applying an annealing separator added in an amount of 0.2 to 10 parts by weight in conversion. 2. The method according to claim 1, wherein the annealing separator comprises 100 parts by weight of MgO and
2. The process for producing a grain-oriented silicon steel sheet having excellent magnetic properties according to claim 1, wherein the compound is added in an amount of 0.2 to 10 parts by weight in terms of Tl and 0.2 to 15 parts by weight of a chloride. 3. An annealing separator further comprises a Bi compound, MgO 10
3. The method for producing a grain-oriented silicon steel sheet having excellent magnetic properties according to claim 1, wherein 0.2 to 10 parts by weight of Bi is added to 0 parts by weight.