JPH07268472A - Grain oriented silicon steel sheet excellent in magnetic property - Google Patents

Abstract

PURPOSE:To produce a grain oriented silicon steel sheet free from deterioration in core loss after stress relief annealing and reduced in core loss by arranging many linear grooves in the surface of a steel sheet. CONSTITUTION:After cold rolling, many linear grooves stretching in a direction intersecting the rolling direction of a steel sheet is arranged in the surface of the steel sheet. At this time, it is desirable that at least one of the side walls constituting each linear grooves consists of a plane inclined toward the groove bottom side with respect to the plane perpendicular to the surface of the steel sheet and its angle of inclination is also regulated to 5-60 deg.. It is preferable that the linear grooves have 30-300mum bottom width and 10-70mum depth and stretch in the direction at <=30 deg. angle of inclination with respect to the axis orthogonal to rolling direction and are disposed at 1-30mm spacing in the rolling direction. By this method, the grain oriented silicon steel sheet, minimal in deterioration in magnetic properties even after stress relief annealing in particular and suitable for transformer iron core, can be obtained.

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 for transformers and other iron core materials for electric equipment and whose iron loss reducing effect does not disappear even after strain relief annealing. It relates to a manufacturing method.

[0002]

2. Description of the Related Art Grain-oriented electrical steel sheets are used as iron cores for transformers and other electric equipment, and are required to have excellent magnetic properties, and particularly low iron loss. This iron loss can be roughly expressed as the sum of hysteresis loss and eddy current loss.By using an inhibitor with a strong inhibitory force, the hysteresis loss can be increased to the Goss orientation, that is, the (110) <001> orientation. It has been significantly reduced by the integration, the reduction of the impurity element that causes the generation of the pinning factor when the domain wall moves when magnetized, and the like. Regarding eddy current loss, on the other hand, increasing the Si content to increase electrical resistance, reducing the steel plate thickness, and forming a coating on the surface of the steel plate with a coefficient of thermal expansion different from that of the base steel The reduction has been attempted by applying tension, reducing the magnetic domain width by miniaturizing the crystal grains, and the like.

In order to further reduce eddy current loss, a method of irradiating a laser beam (Japanese Patent Publication No. 57-2252), a plasma flame (Japanese Patent Publication No. 62-96617), etc. in a direction perpendicular to the rolling direction of the steel sheet. Is proposed. These methods are intended to subdivide magnetic domains by introducing minute thermal strains on the surface of the steel sheet in a linear or dot-like manner to significantly reduce iron loss. However, in these methods, when annealing at high temperature after magnetic domain refinement, the iron loss reducing effect disappears, so it cannot be used as a material for a wound iron core that requires stress relief annealing after irradiation treatment. It was

Therefore, various methods for forming grooves in a steel sheet have been proposed as a method of subdividing magnetic domains that can withstand strain relief annealing. For example, there is a method in which a groove is locally formed in a steel sheet after final finish annealing, that is, after secondary recrystallization, and the magnetic domains are subdivided by the diamagnetic field effect. There are mechanical processing disclosed in Japanese Patent No. 35679, and electrolytic etching after locally removing the insulating coating and the underlying coating by laser light irradiation disclosed in Japanese Patent Laid-Open No. 63-76819. . Further, Japanese Patent Publication No. 62-53579 discloses a method of subdividing magnetic domains by achieving groove formation and recrystallization by stress relief annealing after stamping with a gear type roll,
JP-A-59-197520 discloses a method of forming grooves in a steel sheet before final finish annealing.

[0005]

According to these methods, the magnetic domain refining effect can be maintained even after strain relief annealing, while the iron loss reduction width is the method of irradiating the above-mentioned laser beam or plasma flame. This is insufficient as compared with, and further reduction of iron loss is desired.

The present invention advantageously solves the above problems, and an object of the present invention is to propose a grain-oriented electrical steel sheet with low iron loss, which is free from deterioration of iron loss even after stress relief annealing.

[0007]

Means for Solving the Problems The present inventors have investigated the shape of the groove locally formed in the final cold-rolled sheet for the purpose of developing a manufacturing method capable of stably reducing the iron loss of grain-oriented electrical steel sheet. , Conducted an earnest experiment. That is, Al, Mn, Se, and
A silicon steel slab containing a trace amount of Sb as an inhibitor,
In accordance with the general production of grain-oriented electrical steel sheets, the final cold-rolled sheet having a thickness of 0.23 mm was obtained through hot rolling and two cold rolling steps with intermediate annealing. After that, linear grooves were formed on the cold rolled sheet by machining.

Here, the linear groove has a depth of 20 μm and a bottom width of 250 μm, and the inclination angle of both side walls with respect to the plane perpendicular to the steel plate surface is (a) outside the groove (opposite to the groove bottom). ) To 20
, (B) vertical (0 °), and (c) three kinds of grooves having a 20 ° angle were formed on the groove bottom side. The linear groove was a straight line extending in a direction having an inclination of 10 ° with respect to an axis orthogonal to the rolling direction, and was repeatedly formed at intervals of 3 mm in the rolling direction. Then, after performing decarburization annealing and finish annealing, apply a tension coating,
Then, it was baked and subjected to strain relief annealing at 850 ° C. for 3 hours.
For comparison, (d) decarburization annealing and finish annealing were performed on the steel sheet that was not subjected to the linear groove forming treatment after the final cold rolling, a tension coating was applied, and after baking, 85
A steel sheet which was subjected to strain relief annealing at 0 ° C. for 3 hours was also manufactured.

From the thus obtained steel sheet after stress relief annealing,
Table 1 shows the results obtained by cutting the Epstein test pieces so that the longitudinal direction thereof coincides with the rolling direction and measuring the magnetic properties of the cut Epstein test pieces. As is clear from the table, the steel sheet having linear grooves in which both side walls of (c) are inclined toward the groove bottom side showed the best magnetic properties.

[0010]

[Table 1]

From the above experimental results, it is newly found that, when locally forming a groove in the final cold-rolled sheet, by optimizing the shape of the groove, a lower iron loss than that in the conventional case can be obtained. Then, this invention was completed. That is,
This invention is a grain-oriented electrical steel sheet in which a large number of linear grooves extending in a direction intersecting the rolling direction of the steel sheet are arranged on the surface of the steel sheet, and at least one of the side walls forming the linear groove is on the steel sheet surface. A grain-oriented electrical steel sheet having excellent magnetic characteristics, characterized in that it is a surface inclined to the groove bottom side with respect to a vertical surface (hereinafter referred to as a vertical surface).

Here, the linear groove has an inclination angle of 5 to 60 ° to the groove bottom side with respect to the vertical surface, and the width of the bottom surface.
Iron loss can be reduced by 30 to 300 μm and depth of 10 to 70 μm, extending within 30 ° with respect to the axis orthogonal to the rolling direction and arranged at intervals of 1 to 30 mm in the rolling direction. Is particularly advantageous.

Here, as the silicon-containing steel which is the material of the present invention, any of the conventionally known component compositions is suitable, and the representative compositions are as follows. C: 0.01 to 0.10 wt% (hereinafter simply referred to as%) C is a component useful not only for the refinement of the structure during hot rolling and cold rolling but also for the development of Goss orientation, and at least
The content of 0.01% or more is preferable. However, if the content exceeds 0.10%, the Goss orientation is rather disordered, so the upper limit is preferably about 0.10%.

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 if it is less than 2.0%, the specific resistance is reduced. Not only decreases but also secondary recrystallization
Since the crystal orientation is randomized by α-γ transformation during the final high-temperature annealing performed for purification, and a sufficient iron loss improving effect cannot be obtained, the Si content is preferably set to about 2.0 to 4.5%.

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

As the inhibitor, so-called MnS, MnSe
There are systems and AlN systems. First, in the case of MnS, MnSe system, S
At least one selected from e and S is 0.005
It is contained in the range of 0.06%. Se and S are both powerful elements as inhibitors. From the viewpoint of securing the suppression power, at least about 0.005% is required, but if it exceeds 0.06%, the effect is impaired, so it is preferable to set the lower and upper limits to about 0.01% and 0.06%, respectively.

In the case of AlN system, Al: 0.005 to 0.10%,
N: contained in the range of 0.004 to 0.015%. The Al and N ranges are also set to the above ranges for the same reason as in the case of the MnS and MnSe systems described above. Mn mentioned above
S, MnSe and AlN can be used together.

As the inhibitor component, the above-mentioned S, S
e, Al, Cu, Sn, Cr, Ge, Sb, Mo, Te, Bi and P
Etc. are advantageously suited, so that a small amount can be included in each case. Here, the preferred addition ranges of the above components are Cu, Sn, Cr: 0.01 to 0.15%, Ge, Sb, Mo, Te,
Bi: 0.005 to 0.1%, P: 0.01 to 0.2%, and each of these inhibitor components can be used alone or in combination.

[0019]

By introducing a linear groove on the surface of the steel sheet, a free magnetic pole is generated when the electromagnetic steel sheet is magnetized, and the magnetic domain width is reduced so as to reduce the magnetic energy generated by this magnetic pole, resulting in abnormal eddy current loss. Is known to decrease.

However, the magnetic flux lines tend to bypass the lower part of the linear groove to suppress the generation of magnetic poles, and the effect of reducing the magnetic domain width due to the generation of magnetic poles is diminished, so that the reduction of eddy current loss is suppressed. Will be done. This detour of the magnetic flux lines is more likely to occur when the side wall of the linear groove is inclined from the plane perpendicular to the steel plate surface to the outside of the groove. Inclination is very effective in suppressing the decrease of the magnetic domain subdivision effect due to the detour of the magnetic flux lines. Here, FIG. 1 illustrates the cross-sectional shape of the linear groove that conforms to the present invention.

Both side walls forming the linear groove are shown in FIG.
As shown in (a), it is desirable to incline toward the groove bottom side, but as shown in (b) or (c) of the figure, only one of the side walls inclines toward the groove bottom side. In this case, the effect of improving iron loss can be expected. It is more preferable that the side wall be flat, but as shown in Fig. 6 (d), the intersection line between the bottom surface and the side wall and the upper edge of the side wall are rounded as long as the inclination of the side wall is not impaired. Good.

Further, the linear groove has an inclination angle of 5 to 60 ° to the groove bottom side with respect to the vertical surface, and has a bottom width of 30 to 300 μm and a depth of 10 to 70 μm. It is particularly advantageous for reducing the iron loss that the inclination with respect to the axis orthogonal to the axis extends within 30 ° and is arranged at intervals of 1 to 30 mm in the rolling direction. That is, when the inclination angle to the groove bottom side with respect to the vertical surface is less than 5 °, the effect of suppressing the detour of the magnetic flux lines is small, and when it exceeds 60 °,
Although the effect of suppressing the detour of the magnetic flux lines is large, the hysteresis loss increases, so the inclination angle to the groove bottom side with respect to the vertical surface is
It is preferably -60 °. When the groove width is less than 30 μm or the groove depth is less than 10 μm, the magnetic pole generation amount is small and the magnetic domain subdivision effect is small, so that the iron loss cannot be sufficiently reduced. On the other hand, the groove width is 300 μ
When it exceeds m or when the groove depth exceeds 70 μm, the magnetic flux density is remarkably reduced. Next, when the spacing between the grooves is less than 1 mm, the magnetic flux density is remarkably reduced, while when the spacing between the grooves exceeds 30 mm, the magnetic domain subdivision effect is small and the iron loss reduction becomes insufficient. If the inclination of the linear groove extending direction with respect to the axis orthogonal to the rolling direction exceeds 30 °,
The iron loss reduction effect is significantly impaired. The direction in which the linear grooves extend may be orthogonal to the rolling direction,
Of course.

The linear grooves can be formed after the final cold rolling or after the decarburization annealing. In addition to the mechanical method as the method, when performing after the final cold rolling,
An electrochemical method such as resist-electrolytic etching or a chemical method such as etching may be used. That is, the groove formation can be easily achieved by applying the resist agent to the non-corrosion portion other than the groove portion having the shape according to the present invention.

[0024]

【Example】

Example 1 C: 0.040%, Si: 3.32%, Mn: 0.065%, Mo: 0.013
%, Se: 0.020%, Al: 0.025%, Sb: 0.025% and N: 0.008% of a silicon steel slab heated at 1360 ° C for 3 hours and then hot rolled into a 2.4 mm thick hot-rolled sheet. After, 97
Two cold-rolls with intermediate annealing at 0 ° C for 3 minutes
The final cold-rolled sheet had a thickness of 0.23 mm. Then, linear grooves were formed in the steel sheet before finish annealing by machining. The linear groove has a depth of 20 μm and a bottom width of 200 μm. The inclination angle of both side walls with respect to the vertical plane is changed from 40 ° on the outside of the groove to 40 ° on the bottom side of the groove and is orthogonal to the rolling direction. A straight line extending in the direction of 10 ° with respect to the axis was formed, and the interval in the rolling direction was 5 mm.

Next, after decarburization annealing and finish annealing, a tension coating is applied and baked at 850 ° C.
Then, stress relief annealing was performed for 3 hours. From the thus obtained steel sheet after stress relief annealing, Epstein test pieces were cut so that the longitudinal direction thereof coincided with the rolling direction, and the respective magnetic characteristics were measured. The results are shown in FIG. As is clear from the figure, extremely good iron loss can be obtained when both side walls are inclined toward the groove bottom side.

Example 2 C: 0.044%, Si: 3.26%, Mn: 0.067%, Mo: 0.012
%, Se: 0.017%, Al: 0.026%, Sb: 0.026%, and N: 0.008%, a silicon steel slab heated at 1360 ° C for 3 hours and hot-rolled to form a 2.4 mm thick hot-rolled sheet. After, 97
Two cold-rolls with intermediate annealing at 0 ° C for 3 minutes
The final cold-rolled sheet had a thickness of 0.23 mm. Then, linear grooves were formed in the steel sheet before finish annealing by machining. The linear groove has a depth of 25 μm and a bottom width of 250 μm. The inclination angle of both side walls with respect to the vertical plane is changed from 20 ° outside the groove to 40 ° toward the groove bottom side and is orthogonal to the rolling direction. It was formed in a straight line extending in the direction, and the interval in the rolling direction was 3 mm. Next, decarburization annealing and finish annealing were performed, and then a tension coating was applied and baked, and strain relief annealing was performed at 850 ° C. for 3 hours.

For comparison, a steel sheet subjected to the same treatment after chemical groove polishing to widen and smooth the groove bottom surface, and a product sheet after strain relief annealing without groove formation were respectively compared. I prepared.

From the steel sheet thus obtained after strain relief annealing,
Table 2 shows the results of cutting the Epstein test piece so that its longitudinal direction coincides with the rolling direction and measuring the magnetic properties of each. As is clear from the table, extremely good iron loss is obtained when at least one side wall is inclined toward the groove bottom side.

[0029]

[Table 2]

[0030]

INDUSTRIAL APPLICABILITY The grain-oriented electrical steel sheet of the present invention has good magnetic properties and is stable, and the deterioration of the magnetic properties is extremely small even after stress relief annealing. When applied, excellent transformer characteristics can be obtained.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a shape of a linear groove.

FIG. 2 is a graph showing the relationship between the inclination angle of the linear groove side wall and iron loss.

Front Page Continuation (72) Inventor Keiji Sato 1 Kawasaki-cho, Chuo-ku, Chiba, Chiba Prefecture Technical Research Division, Kawasaki Steel Co., Ltd. Technology Research Division, Inc.

Claims (3)

[Claims] 1. A grain-oriented electrical steel sheet in which a large number of linear grooves extending in a direction intersecting with a rolling direction of a steel sheet are arranged on a surface of the steel sheet, and at least one of side walls forming the linear groove is
A grain-oriented electrical steel sheet having excellent magnetic properties, characterized by having a surface inclined to the groove bottom side with respect to a surface perpendicular to the steel sheet surface. 2. The grain-oriented electrical steel sheet according to claim 1, wherein the linear groove has an inclination angle to the groove bottom side with respect to a plane perpendicular to the steel sheet surface of 5 to 60 °. 3. The linear groove has a bottom width of 30 to 300 μm and a depth of 10 to 70 μm, extends in a direction within 30 ° with respect to an axis orthogonal to the rolling direction, and is 1 to 30 mm in the rolling direction. The grain-oriented electrical steel sheet according to claim 1, wherein the grain-oriented electrical steel sheets are arranged at intervals of.