JPH0841602A - Grain-oriented silicon steel sheet excellent in magnetic property and its production - Google Patents

Abstract

PURPOSE:To stably produce a grain-oriented silicon steel sheet having excellent core loss properties by forming an area in which one kind among Ga, In, Sn, Pb and Bi is diffused on the faces of linear grooves. CONSTITUTION:Silicon steel slag, e.g., contg. a trace of Al, Mn, Se and Sb as inhibitor forming components is subjected to hot rolling and cold rolling into a cold rolled sheet. This is subjected to electrolytic etching treatment to form many linear grooves stretching in a direction crossed with the rolling direction on the surface. Along at least one face among the bottom face and both side faces of the linear grooves, an area in which at least one kind selected from Ge, In, Sn, Pb and Bi and the oxides and sulfates of the same components is diffused into the steel sheet is formed. For this purpose, each substance is adhered to the grooves, and annealing is executed at >=400 deg.C. Thus, the material effective for the application to the iron core of a transformer can be produced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a grain-oriented electrical steel sheet having excellent magnetic properties, which is suitable as an iron core material for transformers and other electrical equipment, and a method for producing the same.

[0002]

2. Description of the Related Art Grain-oriented electrical steel sheets are mainly used as iron cores for transformers and other electrical equipment, and are required to have excellent magnetic properties, and especially low iron loss. This iron loss is
It can be roughly expressed by the sum of the hysteresis loss and the eddy current loss, and the hysteresis loss can be obtained by using the inhibitor having a strong suppressing force to change the crystal orientation to the Goss orientation, that is, (11
0) It has been drastically reduced by highly accumulating in the [001] direction and reducing the impurity element that causes generation of a pinning factor when the domain wall moves when magnetized. On the other hand, regarding eddy current loss, increasing the Si content to increase electrical resistance, thinning the steel plate thickness, and forming a coating on the surface of the steel plate base metal with a coefficient of thermal expansion different from that of the base iron The reduction has been achieved by applying tension to iron and reducing the magnetic domain width by refining the crystal grains.

More recently, due to the reduction of eddy current loss,
As a technique for further reducing iron loss, there has been proposed a method of irradiating a laser beam (Japanese Patent Publication No. 57-2252) or a plasma flame (Japanese Patent Publication No. 62-96617) in a direction perpendicular to the rolling direction of the steel sheet. It was These methods subdivide the magnetic domains by introducing fine thermal strains in a linear or spot form on the steel plate surface,
The magnetic domain is subdivided to reduce the iron loss. However, these methods cannot be used as a material for wound cores that require stress relief annealing after irradiation because the iron loss reduction effect disappears when heat treatment at high temperature is performed after magnetic domain refinement. It was

Therefore, various methods utilizing groove formation in a steel sheet have been developed as a magnetic domain refining technique capable of withstanding strain relief annealing. As such a technique, for example, there is a method of locally forming grooves in the steel sheet after finish annealing, that is, after secondary recrystallization, and subdividing magnetic domains by the demagnetizing effect.
As such groove forming means, mechanical processing (Japanese Patent Publication No.
5679) or a method of locally removing the insulating coating and the underlying coating by laser light irradiation and then electrolytically etching (JP-A-63-76819). Further, JP-B-62-53579 discloses a method of subdividing a magnetic domain by achieving groove formation and recrystallization by performing stress relief annealing after pressing with a tooth profile roll. Japanese Patent Publication No. 197520 discloses a method of forming grooves in a steel sheet before finish annealing.

[0005]

Although the groove forming technique as described above makes it possible to maintain the magnetic domain refining effect even after the strain relief annealing, the iron loss can be reduced by the above-mentioned laser beam or plasma flame. However, it is not sufficient compared with the method of irradiating the same, and further reduction of iron loss has been desired. The present invention advantageously responds to the above-mentioned demands, and an object thereof is to propose a novel technique that can stably realize further lower iron loss in the technique of reducing iron loss by forming a groove.

[0006]

Means for Solving the Problems Now, the inventors of the present invention have conducted earnest experiments and studies for the purpose of reducing iron loss of grain-oriented electrical steel sheets, and as a result, in grain-oriented electrical steel sheets having linear grooves on the surface, It has been found that the core loss is significantly reduced as compared with the conventional case by forming a region in which a specific substance is diffused around the linear groove, that is, near the bottom surface and both side surfaces. The present invention builds on the above findings.

That is, the present invention has a large number of linear grooves extending in the direction intersecting the rolling direction on the surface of the steel sheet, and at least one of the bottom surface and both side surfaces of the linear groove.
A region in which at least one selected from Ge, In, Sn, Pb and Bi and oxides and sulfates of these elements is diffused in the steel sheet along the surface is characterized by Is a grain-oriented electrical steel sheet with excellent iron loss characteristics.

In the present invention, the silicon-containing slab is hot-rolled, and then cold-rolled once or twice or more with an intermediate anneal to obtain a final product sheet thickness, followed by decarburizing-annealing. In a method for producing a grain-oriented electrical steel sheet comprising a series of steps for applying finish annealing, a steel sheet that has undergone final cold rolling is formed with a number of linear grooves in a direction intersecting the rolling direction, and after final finish annealing, At least one selected from Ge, In, Sn, Pb and Bi, and oxides and sulfates of these elements is attached to at least one of the three surfaces of the bottom surface and both side surfaces of the linear groove. After that, it is annealed at a temperature of 400 ° C or higher, which is a method for producing a grain-oriented electrical steel sheet having excellent iron loss characteristics.

In the present invention, the linear groove formed on the surface of the steel sheet has a width of 30 to 300 μm, a depth of 10 to 70 μm,
It is preferable that the groove interval is 1 to 30 mm, and the angle of intersection with the rolling direction is within 30 ° with respect to the direction perpendicular to the rolling direction.

The present invention will be described in detail below. First, the experimental results that are the basis of the present invention will be described. A steel slab containing a small amount of Mn, Se and Al as inhibitor forming components was subjected to hot rolling according to a conventional method and then cold rolling twice with intermediate annealing interposed therebetween to obtain a final cold rolled sheet having a thickness of 0.23 mm. Then, a resist ink was applied to the cold rolled plate to mask it, leaving an uncoated portion corresponding to the desired linear groove shape. Here, the shape of the non-coated portion was a straight line with a width of 200 μm parallel to the plate width direction. Such straight non-coated portions were left with a gap of 3 mm in the rolling direction. Next, a linear groove having a depth of 20 μm was formed by electrolytic etching using a NaCl bath. And after removing the resist agent,
After performing decarburization annealing and finish annealing, a paste obtained by kneading Ge, In, Sn, Pb, and Bi oxide fine powders with a resin was applied to the groove portion, and then dried,
Annealing was carried out at various temperatures ranging from 250 to 850 ° C. Then, after applying the tension coating and baking,
Strain relief annealing was performed for 3 hours.

For comparison, a steel sheet not subjected to linear groove forming treatment on the final cold-rolled sheet and a linear sheet parallel to the sheet width direction with a width of 200 μm, a depth of 20 μm and a groove interval of 3 mm The steel sheet on which the linear grooves were formed was subjected to decarburization annealing and finish annealing under the same conditions as above, then applied with a tension coating, baked, and then subjected to strain relief annealing.

From each of the steel plates thus obtained, Epstein test pieces were cut out so that the longitudinal direction thereof coincided with the rolling direction, and the measurement results of the respective magnetic properties are shown in FIG. As shown in FIG. 1, when a paste containing each metal of Ge, In, Sn, Pb and Bi was applied and annealed at a temperature of 400 ° C. or higher, not only the groove but also the groove was formed. Compared with conventional materials, iron loss is significantly reduced. In addition, when the metals of Ge, In, Sn, Pb, and Bi, their sulfates, or a mixture thereof were applied, the reduction of iron loss was similarly confirmed.

[0013]

[Function] Now, along at least one of the three surfaces of the bottom surface and both side surfaces of the linear groove, Ge, In, Sn, Pb and Bi and oxides and sulfates of these elements are selected. It is a fact that the iron loss characteristics are improved by forming a region (hereinafter referred to as a diffusion region) in which at least one kind is diffused in the steel sheet, but the reason for this is not yet clear. Not not. However, it can be explained by any of the following theories.

First, the subdivision of magnetic domains will be described. That is, the linear groove introduced on the surface of the steel sheet produces a free magnetic pole when the electromagnetic steel sheet is magnetized, and the magnetic domain width decreases so as to reduce the magnetic energy generated by this magnetic pole,
As a result, it is known that abnormal eddy current loss is reduced. However, since the magnetic flux lines tend to bypass the lower part of the linear groove to prevent the magnetic pole from being generated, the effect of reducing the eddy current loss is reduced accordingly. This detour of the magnetic flux lines occurs against the magnetic anisotropy of the grain-oriented silicon steel sheet, so by strengthening the magnetic anisotropy around the linear grooves,
It is possible to suppress the reduction of the magnetic domain subdivision effect due to the detour of the magnetic flux lines. In other words, if a region with increased magnetic anisotropy is formed around the linear groove, the magnetic anisotropy here is strengthened, and the detour of the magnetic flux line can be effectively prevented. The subdivision effect can be strengthened. Therefore, the reason why the iron loss is improved is that the magnetic anisotropy around the linear groove is increased by forming the diffusion region.

Further, by diffusing these elements in the region around the linear groove, a region having a saturation magnetostriction value different from that of the surrounding region is formed, and a mechanism for enhancing the magnetic pole generated in the linear groove portion due to the difference in strain sensitivity between the two. Further, the iron loss improving effect can be explained also by the mechanism in which the increase of the internal stress due to the existence of the linear diffusion region enhances the magnetic domain refining effect.

Here, as a distribution form of the diffusion region, a region adjacent to the bottom surface of the linear groove or at least one of both side surfaces of the linear groove, that is, as shown in FIG. 2, is adjacent to the bottom surface of the linear groove. The strip-shaped region 1 extending along the surface may be at least one of the strip-shaped regions 2a and 2b that are adjacent to both side surfaces and extend along the surface. If the thickness t (see FIG. 2) of the diffusion region is less than 50 μm, the rotation of magnetization is likely to occur, so it is preferable to set the thickness to 50 μm or more. On the other hand, if the thickness of this region is too large, the magnetic resistance of the steel sheet is increased. The thickness of this region is
It is preferably 400 μm or less.

It is more preferable that the above-mentioned region is continuously formed in the plate width direction along the linear groove, but it is not always necessary to be continuous, and it is intermittent like a broken line. May be. In addition, the crystal grain orientation in this region should be the same as that of the periphery, that is, in the same crystal grain,
It is desirable that the Si region is formed, but grain boundaries or fine crystal grains may be present in this region.

Regarding the shape of the linear groove, width: 30 to 300 μ
It is preferable that m is m, depth is 10 to 70 μm, groove interval is 1 to 30 mm, and angle of intersection with the rolling direction is within 30 ° with respect to the direction perpendicular to the rolling direction. This is because when the groove width is less than 30 μm and the groove depth is less than 10 μm,
This is because the amount of magnetic poles generated is small, so a sufficient domain refinement effect cannot be obtained, while when the groove width exceeds 300 μm and the groove depth exceeds 70 μm, the magnetic flux density is significantly reduced. . Further, if the groove spacing is less than 1 mm, the magnetic flux density is remarkably reduced, while if it exceeds 30 mm, the magnetic domain refining effect is reduced and the iron loss is not sufficiently reduced. Further, if the direction of the linear groove deviates from the range of ± 30 ° with respect to the direction perpendicular to the rolling direction, the effect of domain refinement will be sharply reduced, and the effect of reducing iron loss will be significantly deteriorated.

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.

Next, in order to form a diffusion region around the linear groove, after finish annealing, a substance having a magnetocrystalline anisotropy constant larger than that of the raw material silicon steel, such as Ge, In, Sn, Pb and It is possible to apply Bi and at least one selected from oxides and sulfates of these elements to either the bottom surface or both side surfaces of the linear groove and anneal at a temperature of 400 ° C or higher. preferable.

If the annealing temperature is less than 400 ° C.,
As shown in FIG. 1, the annealing temperature must be 400 ° C. or higher because the formation of the diffusion region around the groove is insufficient and a satisfactory domain refinement effect cannot be obtained.
If the annealing temperature exceeds 850 ° C, the alloy layer as the diffusion region may disappear, so the annealing temperature is preferably 850 ° C or lower. Further, this step needs to be performed after finish annealing, and it is difficult to stably form the above region before finish annealing.

In order to form the diffusion region, the technique of performing annealing after applying the paste in the experiment shown in FIG. 1 is suitable, but other than this, vacuum evaporation, sputtering, vapor deposition A film forming process such as phase chemical reaction vapor deposition, or a deposition technique such as plating, plasma spraying or electrostatic coating may be used. Here, Ge, In, Sn,
The diffusion amount of at least one selected from Pb and Bi and oxides and sulfates of these elements is more preferably 0.5 wt% or more. This is because if it is less than 0.5 wt%, the effect of enhancing the magnetic anisotropy is small, and it is not possible to effectively suppress the detour of the magnetic flux line below the linear groove to improve the iron loss.

The electromagnetic steel sheet targeted by the present invention is not particularly limited, and any conventionally known electromagnetic steel sheet can be applied. The preferred composition is as follows. C: 0.01 to 0.10 wt% (hereinafter simply referred to as%) C is an element useful not only for uniform refinement of the structure during hot rolling and cold rolling but also for development of Goss orientation, and at least 0.01%. However, if the content exceeds 0.10%, the Goss orientation will be disturbed, so 0.01 to 0.10%
It is preferable to set the degree.

Si: 2.0 to 4.5% Si increases the specific resistance of the steel sheet and effectively contributes to the reduction of iron loss, but if it exceeds 4.5%, the cold rolling property is impaired, while 2.0%
If it does not satisfy the requirement, not only the specific resistance decreases, but also the crystal orientation is randomized by α-γ transformation during the finish annealing performed for secondary recrystallization and blunting, and a sufficient iron loss reduction effect is obtained. Therefore, the amount of Si is preferably set to about 2.0 to 4.5%.

Mn: 0.02 to 0.12% Mn requires at least about 0.02% in order to prevent hot brittleness, but if it is too much, the magnetic properties deteriorate, so the upper limit is preferably set to about 0.12%. .

The inhibitors added to suppress grain growth of crystal grains having an orientation other than the Goth orientation and effectively grow the Goth orientation include MnS, MnSe and AlN.・ MnS, MnSe system; at least 1 selected from Se and S
Species: 0.005 to 0.06% Se and S are all effective elements as inhibitors, and at least about 0.005% is required from the viewpoint of securing inhibitory power, but if it exceeds 0.06%, the effect is rather impaired. In either case of single addition or complex addition, the content is preferably about 0.005 to 0.06%. AlN system; Al: 0.005 to 0.10%, N: 0.004 to 0.015% The range of Al and N is also set to the above range for the same reason as in the case of the above MnS and MnSe systems. Here, the above-mentioned MnS, MnSe system and AlN system can be used together.

In addition to S, Se and Al described above, Cu, Sn, Cr, Ge, Sb, Mo, Te, and
Bi and P etc. can be used. Here, the preferred addition ranges of the above components are Cu, Sn, Cr: 0.01 to 0, respectively.
15%, Ge, Sb, Mo, Te, Bi: 0.005 to 0.1%, P: 0.01
.About.0.2%, and each of these inhibitors can be used alone or in combination.

[0028]

【Example】

Example 1 A silicon steel slab containing trace amounts of Al, Mn, Se and Sb as inhibitor forming components was subjected to hot rolling according to a conventional method and then cold rolling twice with intermediate annealing interposed between them to obtain a final cold 0.23 mm thickness. It was a rolled sheet. Then, resist coating was applied to the cold rolled plate to mask it, leaving a non-coated portion corresponding to the linear groove shape. Here, the shape of the non-coated portion was a straight line having a width of 200 μm extending in the plate width direction. Such a linear non-coated portion was left at a distance of 3 mm in the rolling direction. Next, a linear groove having a depth of 20 μm was formed by electrolytic etching using a NaCl bath. Next, after removing the resist agent, decarburization annealing and finish annealing were performed, and then a paste prepared by kneading various substances shown in Table 1 with a resin was applied to the groove portion, dried, and baked, Annealing was performed at each temperature of ℃ and 750 ℃.

For comparison, a steel plate not subjected to linear groove forming treatment on the final cold-rolled sheet and a straight line parallel to the sheet width direction with a width of 200 μm, a depth of 20 μm and a rolling direction interval of 3 mm After decarburization annealing and finish annealing were performed in the same manner on the steel sheet from which the resist agent was removed in which the linear grooves were formed,
Strain relief annealing was performed at 50 ° C. for 3 hours.

Epstein test pieces were cut from each of the thus obtained steel sheets after stress relief annealing so that the longitudinal direction thereof coincided with the rolling direction, and the measurement results of the respective magnetic properties are shown in Table 1.

[0031]

[Table 1]

As is clear from Table 1, when CaCO ₃ is applied to the linear groove portion according to the present invention and annealed at 800 ° C. or higher, the iron loss is greatly reduced as compared with the comparative material.

Example 2 A silicon steel slab containing trace amounts of Al, Mn, Se and Sb as inhibitor forming components was hot-rolled according to a conventional method and then cold-rolled twice with intermediate annealing to obtain a thickness of 0.23 mm. Cold-rolled sheet. Then, resist coating was applied to the cold rolled plate to mask it, leaving a non-coated portion corresponding to the linear groove shape. Here, the shape of the non-coated portion was a straight line having a width of 200 μm and extending at an angle of 10 ° with respect to the plate width direction. Such linear non-coated portions were left at intervals of 3 mm. Next, a depth of 25 is obtained by electrolytic etching using a NaCl bath.
After forming the μm linear groove, the resist agent was removed, and then decarburization annealing and finish annealing were performed. Then, the linear groove was irradiated with a YAG laser to remove the coating film formed in the linear groove, and then pastes containing various substances were applied and annealed.

For comparison, a steel sheet not subjected to the linear groove forming treatment on the final cold-rolled sheet, width: 200 μm, depth:
A linear groove extending linearly at 20 μm, an interval of 3 mm, and an angle of 10 ° with respect to the plate width direction was formed, and after removing the resist agent, the steel plate on which the YAG laser was irradiated was linearly decarburized and annealed. After finishing annealing, a tension coating was applied and baked, then strain relief annealing was carried out at 850 ° C. for 3 hours.

Epstein test pieces were cut from each of the thus obtained steel sheets after stress relief annealing so that the longitudinal direction thereof coincided with the rolling direction, and the measurement results of the respective magnetic properties are shown in Table 2.

[0036]

[Table 2]

As is clear from Table 2, the steel sheet obtained according to the present invention has significantly reduced iron loss as compared with the comparative material.

[0038]

As described above, according to the present invention, it is possible to stably obtain a grain-oriented electrical steel sheet having excellent iron loss characteristics, which is not deteriorated by strain relief annealing, and is particularly suitable for transformer core applications. It is valid.

[Brief description of drawings]

FIG. 1 is a graph showing the relationship between annealing temperature and iron loss.

FIG. 2 is a schematic diagram showing a form of a diffusion region around a linear groove.

[Brief description of reference numerals]

 1 area 2a area 2b area

Continuation of front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI Technical indication location H01F 1/16 (72) Inventor Keiji Sato 1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba Kawasaki Steel Corporation Steel Development・ In the Steel Research Laboratory, Production Headquarters (72) Inventor Michio Komatsubara, 1 Kawasaki-cho, Chuo-ku, Chiba-shi, Chiba Kawasaki Steel Co., Ltd.

Claims (3)

[Claims] 1. A steel sheet surface having a large number of linear grooves extending in a direction intersecting with the rolling direction, and Ge, Ge along at least one of the three surfaces of the bottom surface and both side surfaces of the linear grooves. In,
A directional electromagnetic field with excellent magnetic properties, characterized by forming a region in which at least one selected from Sn, Pb and Bi and oxides and sulfates of these elements is diffused in a steel sheet. steel sheet. 2. After hot rolling the silicon-containing silicon steel slab,
In the method for producing a grain-oriented electrical steel sheet, which comprises a series of steps in which a final product sheet thickness is obtained by performing cold rolling once or twice or more with an intermediate annealing between them, followed by decarburization annealing and final finishing annealing. A large number of linear grooves are formed on the rolled steel sheet in a direction intersecting the rolling direction, and after final finishing annealing, at least one of the bottom surface and both side surfaces of the linear groove is Ge, In , Sn, Pb and Bi, and at least one selected from oxides and sulfates of these elements are deposited and then annealed at a temperature of 400 ° C or more, which is excellent in magnetic properties. Method for producing grain-oriented electrical steel sheet. 3. The linear groove according to claim 1 or 2,
Width: 30 to 300 μm, depth: 10 to 70 μm, groove interval: 1 to 30
mm, the crossing angle with the rolling direction: Within 30 ° with respect to the direction perpendicular to the rolling direction, a grain-oriented electrical steel sheet with excellent magnetic properties.