JPH08176840A - Low iron loss grain oriented silicon steel sheet not deteriorated in characteristic by stress relief annealing and its production - Google Patents

Abstract

PURPOSE: To propose a means for using a magnetic domain segmenting technique by a groove forming treatment as a fundamental and enhancing the iron loss decreasing effect thereof to the effect equal to or higher than the effect obtainable when plasma or laser treatments are executed. CONSTITUTION: A steel sheet has many linear grooves extending in a direction intersecting with a rolling direction on its either one surface and has different thickness regions of forsterite films on the other surface. As a result, the steel sheet having the low iron loss is obtd.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a low iron loss grain-oriented silicon steel sheet which is suitable as an iron core material for transformers and other electric devices, and in particular, does not deteriorate in iron loss due to strain relief annealing, and a method for producing the same. Is.

[0002]

2. Description of the Related Art Grained silicon steel sheets are mainly used as iron core materials for transformers and are required to have excellent magnetic properties. Particularly, it is important that the energy loss when used as an iron core, that is, the iron loss is low. In order to reduce the iron loss, the crystal orientation is highly aligned with the (110) [001] orientation, the Si content is increased to increase the electric resistance of the steel sheet, the impurities are reduced, and the sheet thickness is reduced. Various attempts have been made to reduce the thickness. As a result, in the steel sheet having a thickness of _{0.23 mm} or less, iron loss W _17/50 value (magnetic flux density 1.7 T, 50 Hz) of 0.9 W / kg or less has been manufactured. However, with the metallurgical method as described above, it is extremely difficult to request further improvement, and even if some improvement is recognized, iron loss improvement is insignificant for the effort. .

Therefore, in recent years, various methods for artificially subdividing magnetic domains have been tried as means for achieving a significant reduction in iron loss. Among them, a method currently industrialized is a method proposed in Japanese Patent Publication No. 57-2252, in which a surface of a steel sheet subjected to finish annealing is irradiated with a laser. This method is intended to subdivide magnetic domains by introducing fine thermal strain due to a laser on the surface of a steel sheet, and to reduce iron loss by subdividing the magnetic domains.

However, in this method, when heat treatment at a high temperature such as strain relief annealing is performed after the magnetic domain is subdivided, the effect of reducing iron loss disappears. Therefore, as a material for a wound iron core which requires strain relief annealing. It could not be used.

On the other hand, as a technique capable of stress relief annealing, Japanese Patent Publication No. 62-54873 discloses that a steel sheet which has been finish annealed is locally removed with an insulating film by a laser or mechanical means, and then the film-removed portion is acidified. A method of locally forming linear grooves by washing or mechanically scribing directly on the base metal with a knife or the like, and then applying a phosphoric acid-based tension-imparting film so as to fill the grooves. But, again
No. 9 discloses that 90 to 220 kg / mm ²
After forming a groove with a depth of more than 5 μm in the base steel part with the load of 75,
Each method of heat treatment at a temperature of 0 ° C. or higher has been proposed. Further, Japanese Patent Publication No. 3-69968 discloses a method of introducing linear notches in a direction substantially perpendicular to the rolling direction of a steel sheet after final cold rolling.

The steel sheets obtained by these methods are common in that they have linear grooves, and the magnetic domain refinement effect by the magnetic poles around the grooves is one of the iron loss improving principles. At present, steel sheets using these methods are industrially produced as steel sheets that do not suffer core loss deterioration due to strain relief annealing.

[0007]

In the steel sheet having the linear grooves described above, the magnetic domains are generated only near the grooves introduced into the surface of the steel sheet, and therefore the improvement of iron loss due to the groove formation is improved by plasma, laser, etc. Compared with the magnetic domain subdivision method using local thermal strain due to, W _17/50 value is about _0.02-0.03W / kg
Is inferior.

[0008] A technique for achieving subdivision of the magnetic domain width by partitioning and forming locally heterogeneous regions in the surface layer of the base metal containing the coating on the surface of the steel sheet without affecting secondary recrystallization is also known. Proposed. That is, JP-A-60-92479
Japanese Patent Laid-Open No. 60-92481 discloses a steel sheet in which the thickness of a forsterite coating is locally changed, and Japanese Patent Laid-Open No. 60-92481 discloses a steel sheet in which a forsterite coating is locally provided with a defect region.
Japanese Patent Laid-Open No. 60-103124 discloses a steel sheet in which foreign matter having a composition different from that of the ground iron is locally arranged on the surface of the ground iron, and JP-A-60-
Japanese Patent No. 103183 discloses a steel sheet in which a forsterite coating is locally provided with a glass coating having a different composition.

However, since the iron loss improving margin of these steel sheets is smaller than that of steel sheets treated with plasma or laser or steel sheets having linear grooves on the surface, they have not been industrialized in practice.

Therefore, an object of the present invention is to propose a means for raising the iron loss reducing effect to a level equal to or higher than that in the case where plasma or laser treatment is performed, based on the magnetic domain refining technique by groove formation treatment.

[0011]

Means for Solving the Problems The inventors of the present invention have conducted extensive studies in accordance with the above-mentioned problems, and as a result, in a grain-oriented silicon steel sheet having a linear groove on the surface of the steel sheet, a groove on the back surface thereof. By applying the method of forming a different thickness region on the forsterite coating on the surface where the above is not introduced, an effect that is not comparable to the case where each means is individually implemented is obtained, and eventually the iron loss of the steel plate is reduced by plasma or laser. The inventors have newly discovered that the iron loss of the treated steel sheet can be improved to the same level or more, and have completed the present invention. At the same time, it was also found that it is effective to adhere Sn compounds such as SnO ₂ and SnSO ₄ to the surface of the steel sheet for forming the different thickness regions.

That is, according to the present invention, a large number of linear grooves extending in a direction intersecting the rolling direction are provided on any one surface of the steel sheet surface, and a different thickness region of the forsterite coating film is provided on the other surface. This is a low iron loss grain-oriented silicon steel sheet whose characteristics are not deteriorated by strain relief annealing. Here, the different thickness region of the forsterite coating is preferably a continuous or discontinuous linear region.

The grain-oriented silicon steel sheet is obtained by hot-rolling a silicon-containing steel slab and then cold rolling it once or two or more times with intermediate annealing to obtain a final product sheet thickness. Decarburization and primary recrystallization annealing are performed, and then Mg is applied to the surface of the steel sheet.
In a method for producing a grain-oriented silicon steel sheet, which comprises a series of steps of applying an annealing separator containing O 2 as a main component, then performing secondary recrystallization annealing and purification annealing, whichever surface of the steel sheet has undergone final cold rolling. On one surface, forming a large number of linear grooves in a direction intersecting the rolling direction, prior to the application of the annealing separator, on the other surface of the steel sheet, oxide or sulfide, especially Sn0 ₂ or It can be manufactured by a method characterized in that SnSO ₄ is locally adhered and a different thickness region of the forsterite coating is formed on the other surface of the steel sheet surface after the purification annealing.

[0014]

Next, the experimental results which are the basis of the present invention will be described. That is, one of the surfaces of the final cold-rolled sheet having a thickness of 0.22 mm, which has the typical composition shown in Table 1, is applied with resist etching by gravure offset printing, and electrolytic etching to obtain a width of 150 μm and a depth of 25 μm. In addition, linear grooves extending at an inclination angle of 10 ° with respect to the rolling direction were introduced with an interval of 3 mm in the rolling direction. After that, the steel plate was divided into 7 parts, and after the chemicals shown in Table 2 were mixed into the paste on the other surface of the surface of the 6 divided steel plates, that is, the surface on which no linear groove was introduced, each steel plate was prepared as shown in FIG. As shown, it was applied in a line of 0.020 mm width at a pitch of 5 mm in a direction orthogonal to the rolling direction (applied amount: about 1 g / m ² ). The chemical was not applied to the remaining one steel plate.

[0015]

[Table 1]

[0016]

[Table 2]

Then, after decarburizing and primary recrystallization annealing, an annealing separator containing MgO as a main component was applied to the surface of the steel sheet, followed by final finishing annealing. When the surface of the steel sheet after finish annealing was observed, the coating film in the drug-applied portion was different from the color tone of the coating film in the non-applied portion, and the coating thickness was also different. As shown in Fig. 2 as an example of the coating cross-section after finish annealing of the linearly coated SnSO ₄ layer, the coating on the chemical coating part is thicker than the coating on the non-coating part and deeper on the base metal side. You can see that it is invading.

Table 3 shows the results of an examination of the magnetic properties of each steel sheet after finish annealing. From the table, it is understood that the iron loss is reduced when any of the chemicals is applied, that is, when the coating has a different thickness region. Especially iron loss W _17/50 when SnSO ₄ and SnO ₂ are applied
The improvement margin of the value is as large as about 0.05 W / kg.

[0019]

[Table 3]

Further, Table 4 shows the magnetic characteristics of the samples coated with tension. In addition, as a comparison, after applying tension coating to the surface of the final annealed sheet obtained without forming linear grooves in the same process as above, plasma was applied at 7 mm intervals in the direction perpendicular to the rolling direction. The iron loss of the steel sheet which was irradiated and subjected to thermal strain to subdivide the magnetic domains is also shown.
From the table, the iron loss of the steel sheet coated with SnSO ₄ and SnO ₂ is
It can be seen that the iron loss is lower than the iron loss of the plasma-treated steel sheet.

[0021]

[Table 4]

Here, the different thickness regions formed in the forsterite coating have a width of 0.01 to 10 mm and an interval of 1 to 50 mm,
It is preferably provided continuously or intermittently. The angle with respect to the rolling direction is arbitrary. That is, the different-thickness region may be in the rolling direction or at a right angle to the rolling direction as long as it is on the surface opposite to the surface having the linear groove.

The linear groove has a width of 0.003 to 0.03 mm, a depth of 0.001 to 0.070 mm, and an intersecting angle with the rolling direction: 60 to
It is preferably formed at 90 ° with an interval of 1 to 30 mm in the rolling direction. That is, when the groove width is less than 0.003 mm and the groove depth is less than 0.001 mm, a sufficient magnetic domain subdivision effect cannot be obtained because the amount of magnetic poles is small, while the groove width is 0.030 mm. If it exceeds 0.1 mm or if the groove depth exceeds 0.070 mm, the magnetic flux density is significantly reduced. Also, if the groove spacing is less than 1 mm, the magnetic flux density is significantly reduced.
If it exceeds 30 mm, the effect of subdividing the magnetic domains is reduced and the iron loss cannot be sufficiently reduced. Furthermore, the direction of the linear groove is
If it deviates from the range of 60 to 90 °, the effect of subdividing the magnetic domains will be sharply reduced, and the effect of reducing iron loss will be significantly deteriorated.

As agents used for forming different thickness regions, ZrO ₂ , Cu ₂ O, SnO ₂ , SnSO ₄ , MgSO ₄ , SrSO _4, Bi ₂ O are used.
_{3, CdO, CuO, Co 3} O 4, ZnO, NiO, Sb 2 O 3, Sb 2 O 5, SnO include, inter alia Sn compounds such as SnO ₂ and SnSO ₄ is advantageously suited. Then, these chemicals are applied after the final cold rolling, prior to the application of the annealing separator, according to the above-mentioned preferred embodiment, preferably in an adhesion amount of 0.05 to 3.0 g / m ² , and thereafter,
A forsterite film having a different thickness region is formed by applying an annealing separator having MgO as a main component and then performing secondary recrystallization annealing and purification annealing.

The linear grooves may be formed at any stage before and after the final finish annealing as long as they are after the final cold rolling. Examples of the method of forming the groove include a method of locally performing an etching treatment, a method of scribing with a cutting tool, a method of rolling with a protruding roll, and the like, but the most preferable method is immediately after final cold rolling, resist-electrolysis. It is a method of forming grooves in a steel sheet by an electrochemical method such as etching or a chemical method such as etching.

[0026]

[Example] The final composition of 0.22 mm thickness with the composition shown in Table 5
Gravure offset printing on one surface of the cold-rolled sheet
By resist etching coating and electrolytic etching of
Width: 0.0015mm, depth 0.0025mmm, rolling direction spacing 3mm,
The linear groove was introduced at an angle of 10 ° from the rolling direction. That
After that, the above steel sheet was divided into three, and decarburized and primary recrystallization was performed.
Then, on the other side of both surfaces of each steel plate, SnO₂Or SnSO_FourThe page
After mixing in a strike, it is 0 at a pitch of 5 mm in the direction perpendicular to the rolling direction.
020 mm width linear coating (applied amount about 0.3 g / m ²). Just
Then, apply an annealing separator containing MgO as the main component to the steel plate surface.
After that, final finishing annealing was performed. The film after finish annealing
Observation revealed that a region of different thickness was formed in the coating in the drug application area.
I was

[0027]

[Table 5]

As a comparison, a steel sheet having linear grooves introduced therein and having no different thickness region formed on the opposite surface thereof as described above, a steel sheet having no different thickness regions formed on the opposite surface, and After the tension coating, a steel sheet was prepared by irradiating plasma in a direction perpendicular to the rolling direction at intervals of 7 mm to give thermal strain to subdivide magnetic domains.

Table 6 shows the magnetic properties of the steel sheets thus obtained after finish annealing. From the same table, the iron loss of the steel sheet provided with the different thickness region on the surface opposite to the surface on which the linear groove is formed is Of course, it can be seen that the iron loss of the steel sheet subjected to the plasma treatment is also reduced.

[0030]

[Table 6]

[0031]

According to the present invention, it is possible to reduce the iron loss of a steel sheet that has been subjected to a groove forming treatment to a value lower than that of a steel sheet that has been treated with plasma or laser, and it is possible to provide a steel sheet with a lower iron loss. Become.

[Brief description of drawings]

FIG. 1 is a diagram showing a surface of a steel sheet obtained by linearly applying a chemical to the surface of a final cold-rolled sheet.

FIG. 2 is a view showing a cross section of a film after finish annealing of a portion where SnSO ₄ is linearly applied on the surface of a cold rolled plate.

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[Procedure amendment]

[Submission date] February 21, 1995

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 1

[Correction method] Change

[Correction content]

FIG.

Claims (3)

[Claims] 1. A large number of linear grooves extending in a direction intersecting a rolling direction is provided on one surface of a steel sheet surface, and a different thickness region of a forsterite coating film is provided on the other surface. Low iron loss grain-oriented silicon steel sheet whose characteristics do not deteriorate due to strain relief annealing. 2. The grain-oriented silicon steel sheet according to claim 1, wherein the different thickness region of the forsterite coating is a continuous or intermittent linear region. 3. After hot rolling of a silicon-containing steel slab, 1
Cold rolling twice or more with intermediate or intermediate annealing to obtain the final product sheet thickness, then decarburization / primary recrystallization annealing,
Then, in the method for producing a grain-oriented silicon steel sheet, which comprises a series of steps of applying an annealing separator containing MgO as a main component on the surface of the steel sheet, and then performing secondary recrystallization annealing and purification annealing, a final cold rolling was performed. On either surface of the steel plate,
A large number of linear grooves are formed in the direction intersecting with the rolling direction, and before applying the annealing separator, oxides or sulfides are locally attached to the other surface of the steel sheet, and after purification annealing Forming a different thickness region of a forsterite coating on the other surface of the steel sheet, the method for producing a low iron loss grain-oriented silicon steel sheet, the characteristics of which are not deteriorated by strain relief annealing.