JP3463314B2 - Manufacturing method of electrical steel sheet with excellent magnetic properties - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is particularly suitable for transformers and other core materials for electric equipment, and the effect of reducing iron loss is not lost even after strain relief annealing. The present invention relates to a method for manufacturing a grain-oriented electrical steel sheet having excellent magnetic properties. [0002] Grain-oriented electrical steel sheets are used as iron cores for transformers and other electrical equipment, and are required to have excellent magnetic properties, especially low iron loss. This iron loss can be generally expressed by the sum of the hysteresis loss and the eddy current loss. It has been greatly reduced by integration, reduction of an impurity element which causes generation of a pinning factor at the time of domain wall movement when magnetized, and the like. On the other hand, regarding eddy current loss, increasing the Si content to increase the electrical resistance, reducing the thickness of the steel sheet, forming a film with a different thermal expansion coefficient from that of the Attempts have been made by applying tension, reducing the domain width by refining 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 Application Laid-Open No. 62-96617) or the like in a direction perpendicular to the rolling direction of the steel sheet. Has been proposed. In these methods, magnetic domains are subdivided by introducing minute thermal strain into the surface of a steel sheet in a linear or dot-like manner, and an attempt is made to significantly reduce iron loss. However, in these methods, when annealing at a high temperature after the domain refining, the iron loss reduction effect is lost, it can not be used as a material for wound cores that require strain relief annealing after irradiation treatment Was. Therefore, various methods of forming grooves in a steel sheet have been proposed as a magnetic domain refining method capable of withstanding strain relief annealing. For example, there is a method in which a groove is locally formed in the steel sheet after the final annealing, that is, after the secondary recrystallization, and the magnetic domain is subdivided by the demagnetizing effect. Mechanical processing disclosed in 35679, or electrolytic etching after locally removing the insulating film and the underlying film by laser light irradiation shown in JP-A-63-76819, etc. . Japanese Patent Publication No. 62-53579 discloses a method of subdividing magnetic domains by achieving groove formation and recrystallization by performing stress relief annealing after embossing with a gear type roll,
JP-A-59-197520 discloses a method of forming grooves in a steel sheet before final annealing. According to these methods, the magnetic domain refining effect can be maintained even after strain relief annealing, but the iron loss can be reduced only by the laser light or plasma flame described above. Compared with the irradiation method, it is insufficient, and further reduction in iron loss is desired. The present invention advantageously solves the above-mentioned problem, and can produce a low-loss, grain-oriented electrical steel sheet with no iron loss deterioration even after strain relief annealing, stably and at low cost. The aim is to propose a method. The inventors of the present invention have conducted intensive experiments and studies with the aim of developing a manufacturing method capable of stably reducing the iron loss of grain-oriented electrical steel sheets. In the method of locally forming a groove in a plate, the present inventors have newly found that by devising the shape of the groove, it is possible to obtain a lower iron loss than in the past, and completed the present invention. That is, the present invention is to provide a steel product containing steel, which is hot-rolled, and then cold-rolled once or twice or more with intermediate annealing to obtain a final product sheet thickness.
Then, in a method for manufacturing a grain-oriented electrical steel sheet comprising a series of steps of performing a finish annealing, a steel sheet after final cold rolling has a large number of linear grooves extending in a direction substantially perpendicular to the rolling direction at predetermined intervals in the rolling direction. In the present formation, at least one outer edge of the linear groove is provided with an element having a bent portion in which at least two straight lines are combined at an angle with each other.
A method for producing an electromagnetic steel sheet having excellent magnetic properties, wherein a plurality of elements are arranged in a direction substantially perpendicular to a rolling direction, with a length of each element in a sheet width direction being 50 to 100 μm . The linear groove has an average width of 30 to 300 μm and an average depth of 5 to 100 μm, and has a width of 60 to 300 μm with respect to the rolling direction.
Extending at an angle of 90 ° and arranging the linear grooves at an average interval of 1 mm or more in the rolling direction is particularly advantageous for reducing iron loss. [0010] Here, as the silicon-containing steel as the material of the present invention, any of the conventionally known component compositions are suitable, and typical compositions are as follows. C: 0.01 to 0.10 wt% (hereinafter simply referred to as%) C is a component useful not only for uniform micronization of the structure during hot rolling and cold rolling, but also for the development of Goss orientation.
Addition of 0.01% or more is preferable. However, if the content exceeds 0.10%, the Goss orientation is rather disturbed. Therefore, 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. However, when the content exceeds 4.5%, the cold rolling property is impaired. Not only decrease, but also secondary recrystallization
Since the crystal orientation is randomized by the α-γ transformation during the final high-temperature annealing performed for purification, a sufficient iron loss improvement effect cannot be obtained, so 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 are deteriorated. Therefore, the upper limit is preferably set to about 0.12%. . As inhibitors, so-called MnS, MnSe
System and AlN system. First, in the case of MnS and MnSe,
e, at least one selected from the group consisting of 0.005 to
It is contained in the range of 0.06%. Se and S are both effective elements as inhibitors. From the viewpoint of securing the suppressing power, at least about 0.005% is required, but if it exceeds 0.06%, its effect is impaired. Therefore, it is preferable that the lower limit and the upper limit are 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 ranges of Al and N are also set to the above ranges for the same reason as in the case of the MnS or MnSe system described above. Mn mentioned above here
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
And the like can be advantageously used, so that they can be contained together in small amounts. Here, the preferable addition ranges of the above components are respectively 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. It is known that when a linear groove is introduced into 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. I have. In the present invention, with respect to the linear groove to be introduced into the surface of the steel sheet, at least one outer edge has a plurality of elements formed by combining at least two straight lines at an angle to each other in a direction substantially orthogonal to the rolling direction. With the arrangement, the reduction of the magnetic domain width is further promoted. Here, a configuration in which at least two straight lines form a plurality of elements combined in an arrangement forming an angle with each other is as follows.
A typical example is a part or all of the outline shape of a polygon such as a shape in which a joint portion of two straight lines is a vertex of a chevron or a shape in which three straight lines are joined in a trapezoidal shape. That is, first, in the case of a linear groove continuous in a direction substantially perpendicular to the rolling direction, as shown in FIGS. 1 (a) to 1 (c), the outer edges of both sides or one side of the linear groove are zigzag. Figure 1 (a) and
When the linear groove shown in (c) is made discontinuous, FIG.
It becomes the linear groove shown in (e). Further, FIG. 1F 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 joint between the straight lines may have an appropriate curvature. A common feature of the shape of the linear groove shown in FIG. 1 is that a straight joint portion is bent at each of the components on the outer edge thereof, whereas a magnetic wall is generated at the bent portion. For this reason, the magnetic domain width can be narrowed by sufficiently increasing the number of straight junctions, as compared with the case where a straight groove having no bending is introduced. Therefore, by making the length l of each element in the plate width direction smaller than the magnetic domain width in the linear groove shown in FIG. 1, eddy current loss due to domain wall movement can be reduced more than in the linear groove. . Here, for the above reason, the length l is 50 to 10
0 μm . The lower limit of the angle α formed by the two straight lines is not particularly defined. However, if the angle is too small, the magnetic domain refining effect is not sufficiently exerted. On the other hand, if the angle approaches 180 °,
Since the magnetic domain refining effect is rather lost, it is preferable to set the angle to 150 ° or less. The formation of the linear grooves can be performed after final cold rolling or after decarburizing annealing. When a linear groove is formed after the final cold rolling, any of an electrochemical method such as a resist-electrolytic etching method and a chemical method such as pickling may be used. That is, by applying a resist agent to non-corrosive parts other than the groove having the shape according to the present invention,
Groove formation can be easily achieved. Examples 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, hot-rolled into a 2.4 mm thick hot-rolled sheet, and then heated at 970 ° C. The steel sheet was subjected to two cold rolling operations with an intermediate annealing for two minutes to obtain a final cold-rolled sheet having a thickness of 0.23 mm. Next, the steel sheet before the finish annealing is applied to the steel sheet as shown in FIG.
The resist ink was applied and masked except for the non-applied portion having a shape corresponding to the shape of the linear groove, as shown in FIG. The application of the resist ink was performed by gravure offset printing, and a gravure ink containing an alkyd-based resin as a main component was used. Here, the non-applied portion is formed by repeating an element having a length of 100 μm in the width direction of the plate, which alternates in the opposite direction in the range of 8 to 80 ° with respect to the width direction of the plate to form a mountain shape.
The line was 100 μm. The non-applied portions composed of such broken lines were left at intervals of 3 mm in the rolling direction. Next, the steel plate was subjected to an electrolytic etching treatment using a NaCl bath to form a polygonal groove having a depth of 20 μm. The electrolytic etching was performed 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, and decarburization annealing is performed.
Next, after finish annealing, a tension coating was applied and baked, followed by strain relief annealing at 800 ° C. for 3 hours. For comparison, a steel sheet not subjected to a linear groove forming process on the final cold-rolled sheet, a depth of 20 μm and a width of 100 μm
m, a linear groove parallel to the sheet width direction with a gap of 3 mm in the rolling direction was formed in the same manner to remove the resist agent, and then the steel sheet was subjected to the same series of steps after decarburization annealing. did. From the steel sheet after the strain relief annealing thus obtained,
An Epstein test piece was cut out so that its longitudinal direction coincided with the rolling direction, and the results of measuring the respective magnetic properties are shown in Table 1. [Table 1] From Table 1, it can be seen that the magnetic properties are improved by introducing the linear grooves into the steel sheet, and in particular, the iron loss is significantly improved by forming the linear grooves into the shape according to the present invention. In addition to the linear grooves described above, 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. According to the present invention, it is possible to stably produce a grain-oriented electrical steel sheet which has good and stable magnetic properties, and in particular, has very little deterioration in magnetic properties even after performing strain relief annealing. It is possible.

BRIEF DESCRIPTION OF THE 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.

Continuation of front page (58) Field surveyed (Int. Cl. ⁷ , DB name) C21D 8/12 H01F 1/16

Claims (1)

(57) [Claims] [Claim 1] After the silicon-containing steel material is hot-rolled, it is subjected to one or two or more cold-rolling steps including intermediate annealing to obtain a final product thickness. In a method for manufacturing a grain-oriented electrical steel sheet comprising a series of steps of performing post-decarburization annealing and then finish annealing, a steel sheet after final cold rolling is provided with a linear groove extending in a direction substantially orthogonal to the rolling direction in a rolling direction. In forming a large number of the linear grooves at predetermined intervals, at least one outer edge of the linear groove is formed by combining at least two straight lines with elements having bent portions combined in an angled arrangement with each other in the width direction of each element.
A method for producing an electromagnetic steel sheet having excellent magnetic properties, wherein a plurality of the steel sheets have a length of 50 to 100 μm and are arranged in a direction substantially perpendicular to a rolling direction.