JPH06299244A - Manufacture of silicon steel sheet having excellent magnetic characteristic - Google Patents

Abstract

PURPOSE:To stably manufacture a grain oriented silicon steel sheet having low iron loss without deteriorating the iron loss even after stress relieving annealing. CONSTITUTION:The manufacturing method of the grain oriented silicon steel sheet is composed of series of processes, i.e., after hot-rolling a silicon contg. steel stock, one time or two or more times of cold rolling including process annealing is applied to form the finish product sheet thickness and thereafter, decarburizing annealing and successively, finish annealing are applied, plural linear grooves are formed so as to extend in the direction crossed almost orthogonally to this rolling direction at prescribed intervals in the rolling direction. Then, at least one of outer edges in these linear grooves has such constitution that plural elements each combined in the arrangement of forming an angle with at least two straight lines mutually are arranged in the direction crossed orthogonally to the rolling direction. By this constitution, the silicon steel sheet having good and stable magnetic characteristics is obtd.

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 suppressing 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 it is possible to stably manufacture a grain-oriented electrical steel sheet having a low iron loss without deterioration of the iron loss even after stress relief annealing at a low cost. The purpose is to suggest a method.

[0007]

Means for Solving the Problems The inventors of the present invention have conducted extensive experiments and studies for the purpose of developing a manufacturing method capable of stably reducing the iron loss of grain-oriented electrical steel sheets, and as a result, the final cold-rolled sheet is locally In the method of forming a groove, it was newly found that iron loss lower than that of the conventional one can be obtained by adding a device to the shape of the groove, and the present invention was completed.

That is, according to the present invention, after the silicon-containing steel material is hot-rolled, it is cold-rolled once or twice or more with intermediate annealing to obtain a final product sheet thickness, and then decarburization-annealed.
Then, in the method for producing a grain-oriented electrical steel sheet comprising a series of steps of performing finish annealing, the steel sheet after the final cold rolling has a large number of linear grooves extending in a direction substantially orthogonal to the rolling direction at predetermined intervals in the rolling direction. In this forming, at least one outer edge of the linear groove is formed by arranging a plurality of elements, which are combined in an arrangement in which at least two straight lines form an angle with each other, in a direction substantially orthogonal to the rolling direction. It is a characteristic method for producing an electromagnetic steel sheet having excellent magnetic properties.

The linear grooves have an average width of 30 to 300 μm and an average depth of 5 to 100 μm, and have an average width of 60 to 60 μm in the rolling direction.
It is particularly advantageous to reduce iron loss by extending at 90 ° and arranging the linear grooves in the rolling direction at an average interval of 1 mm or more.

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
Addition 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 ductility 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 inhibitors, so-called MnS and MnSe are used.
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 the lower and upper limits thereof are preferably set 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, S and S described above are used.
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.

[0016]

It is known that when a linear groove is introduced on the surface of a 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 due to the demagnetizing field. And in this invention, regarding the linear groove to be introduced into the surface of the steel sheet, at least one outer edge of the linear groove has a plurality of elements combined in an arrangement in which at least two straight lines form an angle with each other in a direction substantially orthogonal to the rolling direction. The arrayed structure further promotes the reduction of the magnetic domain width.

Here, the configuration in which a plurality of elements combined in an arrangement in which at least two straight lines form an angle with each other are arranged,
A typical example is a part or all of the contour shape of a polygon such as a shape in which two straight line joints are apexes of a chevron or a shape in which three straight lines are trapezoidal. That is, first, in the case of a linear groove continuous in a direction substantially orthogonal to the rolling direction, as shown in a specific example in FIGS. 1 (a) to 1 (c), the outer edge on one side or both sides of the linear groove is zigzag. And also in Figure 1 (a) and
When the linear groove shown in (b) is made discontinuous, as shown in Fig. 1 (d) and
It becomes the linear groove shown in (e). Further, FIG. 1 (f) shows a linear groove having an outer edge formed by joining three straight lines in a trapezoidal shape. In addition,
As shown in FIG. 2, the joining portion between the straight lines may have an appropriate curvature, which is unidirectional.

What is common to the shape of the linear groove shown in FIG. 1 is that the straight joints are bent in each of the constituent elements of the outer edge thereof, while a domain wall is generated in this bent portion. Since it is easy, the magnetic domain width can be narrowed by sufficiently increasing the number of straight line junctions as compared with the case of introducing a straight groove having no bending. Therefore, by making the length l of each element in the plate width direction shown in FIG. 1 narrower than the magnetic domain width in the linear groove, it is possible to reduce the eddy current loss due to the domain wall movement as compared with the linear groove. .

Here, for the above reason, the length l is 50 to 10
It is preferably about 00 μm. The lower limit of the angle α formed by the two straight lines is not particularly specified, but if the angle is too small, the effect of domain refinement will not be sufficiently exerted, so it is desirable to set it to 20 ° or more. On the other hand, the angle is 180
If it gets too close to °, the effect of subdividing the magnetic domains is lost, so it is desirable to set it to 150 ° or less.

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

[0021]

Example: C: 0.040%, Si: 3.32%, Mn: 0.066%,
A silicon steel slab containing Mo: 0.012%, Se: 0.020% and Sb: 0.025% was heated at 1360 ° C for 3 hours and hot-rolled into a hot rolled sheet with a thickness of 2.4 mm, then at 970 ° C. The cold-rolled sheet was subjected to two times of cold rolling with intermediate annealing for 2 minutes to obtain a 0.23 mm-thick final cold-rolled sheet. Then, on the steel sheet before finish annealing,
Then, the resist ink was applied and masked, leaving the non-application portion having a shape corresponding to the shape of the linear groove according to the point shown in FIG. The resist ink was applied by gravure offset printing, and a gravure ink containing an alkyd resin as a main component was used.

Here, the non-coated portion is formed by repeating elements having a length of 100 μm in the plate width direction, which are alternately inverted in the range of 8 to 80 ° with respect to the plate width direction and form a mountain shape.
The line was 100 μm. The non-coating portion composed of such polygonal lines was left at intervals of 3 mm in the rolling direction. Next, the steel sheet was subjected to electrolytic etching treatment using a NaCl bath to form a polygonal groove having a depth of 20 μm.

The electrolytic etching was carried out in a NaCl aqueous solution under the conditions of a current density of 10 A / dm ² and an electrolysis time of 20 s.

Thereafter, the resist agent is removed, decarburization annealing,
Then, after finish annealing, tension coating was applied and baked, and strain relief annealing was carried out at 800 ° C. for 3 hours.

For comparison, a steel plate not subjected to linear groove forming treatment on the final cold-rolled sheet, a depth of 20 μm, and a width of 100 μm
m, the distance in the rolling direction is 3 mm, and straight grooves parallel to the sheet width direction are formed by the same method to remove the resist agent, and then the steel sheet is subjected to the same series of steps after decarburization annealing. did.

From the steel sheet thus obtained after strain 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.

[0027]

[Table 1]

From Table 1, it can be seen that the magnetic properties are improved by introducing the linear groove into the steel sheet, and particularly the iron loss is significantly improved by forming the linear groove according to the present invention. In addition to the above-mentioned linear groove, FIG.
When the same evaluation was performed for the linear grooves shown in (b) to (f), the same results as in Table 1 were obtained.

[0029]

According to the present invention, it is possible to stably manufacture a grain-oriented electrical steel sheet which has good and stable magnetic properties, and in particular, has little deterioration in magnetic properties even after strain relief annealing. Is.

[Brief description of drawings]

FIG. 1 is a schematic view showing a groove shape suitable for the present invention.

FIG. 2 is an enlarged view showing a straight joint portion.

Claims (1)

[Claims] 1. A hot-rolled silicon-containing steel material is subjected to cold rolling once or twice or more with intermediate annealing to obtain a final product sheet thickness, which is followed by decarburization annealing and then finish annealing. In the method for producing a grain-oriented electrical steel sheet consisting of a series of steps to be performed, in the steel sheet after the final cold rolling, a large number of linear grooves extending in a direction substantially orthogonal to the rolling direction are formed at predetermined intervals in the rolling direction. At least one outer edge of the linear groove is configured by arranging a plurality of elements, which are combined in an arrangement in which at least two straight lines form an angle with each other, in a direction substantially orthogonal to the rolling direction, A method for manufacturing electrical steel sheets with excellent magnetic properties.