JPH0688171A - Production of ultrahigh magnetic flux density grain oriented silicon steel sheet - Google Patents

Abstract

PURPOSE:To produce an ultrahigh magnetic flux density grain oriented silicon steel sheet extremely high in magnetic flux density by adding molten steel having a specified component of compsn. in which the content of acid soluble Al and N is prescribed with a specified amt. of Bi. CONSTITUTION:The material contg., by weight, 0.03 to 0.15% C, 2.5 to 4.0% Si, 0.02 to 0.30% Mn, 0.005 to 0.040% S, 0.010 to 0.065% acid soluble Al and 0.0030 to 0.0150% N and contg., at need, 0.05 to 0.50% Sn and 0.01 to 0.10% Cu, and the balance Fe with inevitable impurities is used as a starting material to produce the grain oriented silicon steel sheet. At this time, Bi or a Bi component is added to the molten steel by 100 to 5000g/(molten steel T) expressed in terms of Bi. In this way, the Goss azimuth is highly developed, by which the ultrahigh magnetic flux density grain oriented silicon steel sheet having about 1.95 to 2T magnetic flux density can be obtd.

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 high magnetic flux density unidirectional magnetic steel sheet having a highly developed {110} <001> orientation, that is, a Goss orientation used for an iron core of a transformer or the like.

[0002]

2. Description of the Related Art Unidirectional electrical steel sheets are mainly used as a soft magnetic material for iron core materials of transformers and other electric equipment, and their magnetic characteristics must be good in excitation characteristics and iron loss characteristics. I won't.

Normal magnetic flux density B ₈ (magnetic flux density at a magnetic field strength of 800 A / m) or B is used as an index showing this excitation characteristic.
₁₀ is used, and _{W17 / 50} (5
Iron loss per unit weight when magnetized to 1.7 T at 0 Hz), W _13/60, etc. are used.

The unidirectional electrical steel sheet undergoes secondary recrystallization in the final annealing step at a temperature of 900 ° C. or higher at the final stage of the manufacturing process, and the {110} plane is formed on the steel sheet surface and <00} is formed in the rolling direction.
It is obtained by developing a so-called Goss structure having a 1> axis. Among them, the magnetic flux density B ₈ is 1.8
Those having excellent excitation characteristics of 8T or more are called high magnetic flux density unidirectional electrical steel sheets.

As a typical method for producing a high magnetic flux density grain-oriented electrical steel sheet, Japanese Patent Publication No. 40-15644 and Japanese Examined Patent Publication 5
No. 1-134969 is cited. It can be said that the high magnetic flux density unidirectional electrical steel sheets currently produced on a global scale are produced based on the above two patents.

Therefore, the magnetic flux density B of the product based on the above patent
₈ is 1.88 to 1.95T at most, and 3% Si
The value is about 95% of the saturation magnetic flux density of 2.03T of steel.

In recent years, however, social demands for energy saving and resource saving have become more and more strict, and demands for reducing iron loss and improving magnetization characteristics of unidirectional electrical steel sheets have also become fierce.

On the other hand, technically, a magnetic domain control technique such as laser irradiation has been established as a technique for reducing iron loss by Japanese Patent Publication Nos. 58-5968 and 57-2252.
In this method, the demand for a material with a higher magnetic flux density has become stronger as a means for reducing iron loss.

In other words, the present situation is waiting for the appearance of a means for making the magnetic flux density B ₈ of the conventional high magnetic flux density unidirectional electrical steel sheet closer to the ideal orientation.

As a means for achieving this goal, the present inventor has proposed a method of adding a carbonate-containing material to the molten steel of a conventional high magnetic flux density unidirectional electrical steel sheet containing Al in Japanese Patent Publication No. 57-1565. However, although this method is feasible in the laboratory, it is not practiced on an industrial scale.

Further, the present applicant has proposed a temperature gradient annealing method in Japanese Patent Publication No. 58-50295. Only by this method can a product having a magnetic flux density B ₈ of 1.95 T or more be stably obtained. However, when this method is carried out in a factory-sized coil foam, there is a great loss of heat and energy, namely, heating from one end of the coil and cooling at the other end to create a temperature gradient, which poses a serious problem for industrial production. I was hungry.

[0012]

SUMMARY OF THE INVENTION It is an object of the present invention to avoid such problems and to manufacture an ultrahigh magnetic flux density grain-oriented electrical steel sheet having an extremely high magnetic flux density.

[0013]

The features of the present invention are as follows. 1) By weight, C: 0.03 to 0.15%, Si: 2.5
~ 4.0%, Mn: 0.02-0.30%, S: 0.0
05-0.040%, acid-soluble Al: 0.010-0.
In the production of a material for a unidirectional electrical steel sheet having 065% and N: 0.0030 to 0.0150% as a basic component, Bi or a Bi-containing material in molten steel is 100 to 500 in terms of Bi.
0 g / (molten steel T) is added, The manufacturing method of the super-high magnetic flux density unidirectional electrical steel sheet.

2) C: 0.03 to 0.15% by weight,
Si: 2.5-4.0%, Mn: 0.02-0.30
%, S: 0.005-0.040%, acid-soluble Al:
0.010 to 0.065%, N: 0.0030 to 0.0
In the production of a material for unidirectional electrical steel sheet having a basic component of 150% and Sn: 0.05 to 0.50%, B is contained in molten steel.
i- or Bi-containing material in 100 to 5000 g / in terms of Bi
(Molten steel T) A method for producing an ultra-high magnetic flux density unidirectional electrical steel sheet, which comprises adding T.

3) By weight, C: 0.03 to 0.15%,
Si: 2.5-4.0%, Mn: 0.02-0.30
%, S: 0.005-0.040%, acid-soluble Al:
0.010 to 0.065%, N: 0.0030 to 0.0
150%, Sn: 0.05 to 0.50%, Cu: 0.0
In the production of a material for unidirectional electrical steel sheet containing 1 to 0.10% as a basic component, Bi or Bi-containing material is added to B in molten steel.
A method for producing an ultrahigh magnetic flux density unidirectional electrical steel sheet, which comprises adding 100 to 5000 g / (molten steel T) in terms of i.

The details of the present invention will be described below. The present inventor has been conducting various studies to further increase the magnetic flux density of so-called high magnetic flux density unidirectional electrical steel sheets, but adding Bi to the molten steel for unidirectional electrical steel sheets using aluminum nitride as the main inhibitor. The magnetic flux density B ₈ = 1.93 of the high magnetic flux density unidirectional electrical steel sheet currently marketed by
We have succeeded in producing ultra-high magnetic flux density unidirectional electrical steel sheets of 1.95T or more, which is much higher than T, and 2T.

The reasons for limiting the component composition of the present invention will be described.
If C is less than 0.03%, abnormal grain growth occurs during slab reheating prior to hot rolling, and secondary recrystallization defects called linear fine grains occur in the product, which is not preferable. On the other hand, if it exceeds 0.15%, decarburization in the decarburization annealing step is likely to be incomplete, which causes magnetic aging in the product, which is not preferable.

If Si is less than 2.5%, the eddy current loss of the product increases, and if it exceeds 4.0%, cold rolling at room temperature becomes difficult, which is not preferable.

The above range is necessary for Mn and S to act as auxiliary inhibitors by forming manganese sulfide.

Acid-soluble Al is a main inhibitor constituent element for producing a high magnetic flux density unidirectional electrical steel sheet,
If it is less than 010%, the amount is insufficient and the inhibitor strength is insufficient. On the other hand, if it exceeds 0.065%, the precipitated aluminum nitride becomes coarse and, as a result, the inhibitor strength is lowered, which is not preferable.

Like acid-soluble Al, N is also a main inhibitor constituent element, and if it deviates from the above range, the optimum state of the inhibitor is destroyed, which is not preferable.

Further, Sn is effective as an element for stabilizing the secondary recrystallization of a thin hand-made product, and also has an effect of reducing the secondary recrystallization particle size, so that addition of 0.05% or more is necessary, Even if it exceeds 0.50%, its action and effect are saturated, so from the viewpoint of cost increase, it is limited to 0.50% or less.

Cu is effective as a film-improving element of the Sn-added material, and if it is less than 0.01%, the effect is small and 0.10%.
If it exceeds, the magnetic flux density of the product decreases, which is not preferable.

The addition of Bi to molten steel, which is a feature of the present invention, is effective in the range of 100 to 5000 g / (molten steel T) in terms of Bi. If it is less than 100 g / (molten steel T), the improvement of the magnetic flux density is slight, and if it exceeds 5000 g / (molten steel T), the effect of improving the magnetic flux density is saturated and cracks occur at the end of the hot-rolled sheet, so the upper limit is 5000 g. / (Molten steel T)

The inclusion of Bi in the material for unidirectional electrical steel sheets is described in JP-A-50-72817, JP-A-51-78733, JP-A-53-39922 and the like. However, all of these patents contain S and Se as essential inhibitors, and Sb and As
It is meant as one of the elements having the same action and effect as the above, and is merely positioned as an alternative element of Sb.

Further, it can be said that these patents do not essentially contain Al as an inhibitor element, and are completely different in character from the present invention.

Further inclusion of Bi is described in JP-A-51.
It is also described in JP-A-107499 and JP-A-63-100127. Indeed, these patents are similar to the present invention in that they contain Al as an indispensable inhibitor, but they are positioned as the same acting elements such as Sb and As, and accordingly, there is no description of an example containing Bi addition. It can be said that there is no evidence of Bi's peculiar magnetic flux density improving action as in the present invention, and the idea and character of Bi addition are different.

Particularly, the present invention is characterized by the addition of Bi or Bi-containing material to the molten steel, and it seems that it is not necessary to remain in the raw material if the addition within the above range, and all of the above-mentioned known examples. Since it is premised on the inclusion, it can be said that the character is completely different from the present invention.

Next, the manufacturing process conditions will be described.
Molten steel for adjusting the composition as described above and containing Bi or a Bi-containing material for producing an ultrahigh magnetic flux density unidirectional electrical steel sheet is cast by a usual method. The casting method is not particularly limited. Then, it is rolled into a hot rolled coil by ordinary hot rolling.

Subsequently, the final plate thickness is obtained by one-stage cold rolling or multiple-stage cold rolling including intermediate annealing, but since the high magnetic flux density unidirectional electrical steel sheet is obtained, the final cold rolling reduction ratio (1 In the case of cold rolling of the stage, its rolling ratio is preferably 65 to 95% under strong reduction. The rolling ratio of the stages other than the final rolling need not be specified. Before final cold rolling, annealing is performed at 950 to 1200 ° C. for 30 seconds to 30 minutes, and AlN precipitation control is performed by rapid cooling. The cold rolled sheet rolled to the final product sheet thickness is subsequently decarburized and annealed by a usual method. The conditions of decarburization annealing are not particularly specified, but it is preferable to perform decarburization annealing in a temperature range of 700 to 900 ° C. for 30 seconds to 30 minutes in wet hydrogen or a mixed atmosphere of hydrogen and nitrogen.

After the decarburization annealing, the surface of the steel sheet is coated with an annealing separator having a usual composition by a usual method for preventing seizure in the secondary recrystallization annealing and forming a glass film. The secondary recrystallization annealing is performed at a temperature of 1000 ° C. or higher for 5 hours or longer in hydrogen or nitrogen or a mixed atmosphere thereof. Subsequently, after removing the excess annealing separator, continuous annealing for straightening the coil winding is performed, and at the same time, an insulating coating is applied and baked. Further, magnetic domain subdivision processing such as laser irradiation is performed if necessary. The method of subdividing the magnetic domains is not particularly limited.

[0032]

【Example】

(Example 1) C: 0.08%, Si: 3.05%, M
n: 0.08%, S: 0.025%, acid-soluble Al:
Bi in molten steel containing 0.028% and N: 0.008%
100 to 5000 g / (molten steel T) was added. A sample without addition was also prepared as a comparative material. The steel ingot was slab-rolled at 1250 ° C., then reheated to 1320 ° C. and immediately hot-rolled to obtain a 2.3 mm hot-rolled sheet.

The hot-rolled sheet was annealed at 1100 ° C. to 0.3
Cold rolled to 0 mm. Subsequently, decarburization annealing is performed at 850 ° C., and after applying an annealing separation material containing MgO as a main component, 1200
A final annealing at ℃ was performed. After removing the powder remaining on the plate after finish annealing, a 60 × 300 mm magnetic measurement sample was sheared and
It was subjected to strain relief annealing at 50 ° C. and subjected to magnetic measurement. Table 1 shows the relationship between the added amount of Bi and the magnetic flux density of the product.

[0034]

[Table 1]

As is clear from Table 1, the addition of Bi produces a magnetic flux density B ₈ of 1.95 T which cannot be obtained by the conventional method.
The above excellent product was obtained.

Example 2 The product obtained in Example 1 has 5
Laser was irradiated at a mm pitch to perform magnetic domain subdivision processing. Table 2 shows the measured magnetic values in that state.

[0037]

[Table 2]

As is clear from Table 2, the Bi-added material has a very high magnetic flux density, and therefore the iron loss characteristic after the magnetic domain subdivision is 0.
An extremely excellent product of 90 W / kg or less is obtained, and the best value reaches 0.7 W / kg. Although this value is 0.30 mm thick, it is usually equal to or higher than that after the magnetic domain subdivision of 0.23 mm product of high magnetic flux density material.

(Example 3) C: 0.09%, Si: 3.
3%, Mn: 0.07%, S: 0.025%, acid-soluble Al: 0.027%, N: 0.009%, Sn: 0.1
Bi was added in an amount of 500 g / (molten steel T) to the molten steel containing 5%. The subsequent steps were the same as in Example 1. The results are shown in Table 3.

[0040]

[Table 3]

As shown in Table 3, by adding Bi, a product having a magnetic flux density B ₈ of 1.95 T or more and extremely excellent characteristics was obtained.

Example 4 C: 0.09%, Si: 3.
2%, Mn: 0.08%, S: 0.026%, acid-soluble Al: 0.026%, N: 0.008%, Sn: 0.1
Bi to 500 in molten steel containing 5% and Cu: 0.07%
g / (molten steel T) was added. The same process was performed as in Example 1 except that the cold rolled sheet thickness was 0.23 mm. The results are shown in Table 4.
Shown in.

[0043]

[Table 4]

As shown in Table 4, it is clear that by adding Bi, a product having an extremely excellent magnetic flux density can be obtained.

Example 5 The product obtained in Example 4 has 5
Laser was irradiated at a mm pitch to perform magnetic domain subdivision processing. Table 5 shows the magnetic characteristics in that state.

[0046]

[Table 5]

As is clear from Table 5, the Bi-added material has a very high magnetic flux density, and therefore the iron loss characteristics after the magnetic domain subdivision is 0.
Excellent results of up to 6 W / kg can be obtained.

[0048]

When Bi is added to the molten steel of the grain-oriented electrical steel sheet, a product having an extremely high magnetic flux density is obtained, and the iron loss characteristics after the magnetic domain subdivision treatment are also extremely excellent, which is industrially very valuable. It can be said to be highly beneficial.

Claims (2)

[Claims] 1. By weight, C: 0.03 to 0.15%, Si: 2.5 to 4.0%, Mn: 0.02 to 0.30%, S: 0.005 to 0.040. %, Acid-soluble Al: 0.010 to 0.065%, N: 0.0030 to 0.0150%, balance: when producing a unidirectional electrical steel sheet using as a starting material a material consisting of Fe and unavoidable impurities, B in molten steel
i or Bi-containing material is 100 to 5000 g / in terms of Bi
(Molten steel T) A method for producing an ultra-high magnetic flux density unidirectional electrical steel sheet, which comprises adding T. 2. By weight, C: 0.03 to 0.15%, Si: 2.5 to 4.0%, Mn: 0.02 to 0.30%, S: 0.005 to 0.040. %, Acid-soluble Al: 0.010 to 0.065%, N: 0.0030 to 0.0150%, Sn: 0.05 to 0.50%, Cu: 0.01 to 0.10%, balance: When a unidirectional electrical steel sheet is manufactured using a material composed of Fe and unavoidable impurities as a starting material, B is added to molten steel.
i or Bi-containing material is 100 to 5000 g / in terms of Bi
(Molten steel T) A method for producing an ultra-high magnetic flux density unidirectional electrical steel sheet, which comprises adding T.