KR950002894B1 - Making method of oriented electromagnetic steel plate - Google Patents

Abstract

The steel sheet is made by hot rolling a slab comprising (by wt.%) 2-4% Si, 0.02-0.07% C, 0.02-0.04% soluble Al, 0.06-0.08% Mn, 0.02-0.03% S, 60-90 ppm N, balance Fe and incidental impurities, annealing, high temp. annealing and insulation and/or tension coating. The grooves of 10-300 μm width are formed at intervals of 1-10 mm by rolling the coated steel sheet in a 45-90 deg. direction against the rolling direction. The steel has the reduced iron loss by refinement of magnetic domain.

Description

Iron loss reduction method of oriented electrical steel sheet by magnetic micronization

FIG. 1 is a graph showing the iron loss improvement rate of the oriented electrical steel sheet which is different from the average load at the time of indentation after the stress relief annealing during the double-side indentation and the one-side indentation of the hot annealing plate.

Figure 2 is a photographic picture of the upper and lower surfaces of the steel sheet after the stress relief annealing during double-sided and single-sided indentation, (a) is a photograph of the magnetic domain when the both sides are press-fitted with a load of 80kg / ㎜, (b) The magnetic domain photographs are obtained when indented with a load of 130 kg / mm2.

3 shows microstructure photographs after stress relief annealing of the strain-introduced portion during double-sided indentation and single-sided indentation, (a) is photographed when both sides are press-fitted under a load of 80kg / mm2, and (b) is 130kg per side These are photographs when press-fitted under a load of / mm2.

4 is a picture of the self-structure structure according to the average load during double-side indentation according to the present invention, (a) is a photograph when the load is 40kg / mm2, (b) is a photograph when the load is 80kg / mm, (c ) Is a photograph in the case of 130 kg / mm2 of load.

The present invention relates to a method for producing a grain-oriented electrical steel sheet used as an iron core material of an electric machine, and more particularly, to a reduction in iron loss caused by magnetic domain micronization.

A grain-oriented electrical steel sheet is used as an iron core material for electrical equipment such as transformers, and a material having low magnetic loss and high magnetic flux density is required to reduce power loss and increase efficiency of electrical equipment. In order to improve the magnetoelectric properties of oriented electrical steel sheets, the Japanese Patent Publication No. 1 has a method of reducing grain growth from the {110} <1> Goss orientation by reinforcing grain growth suppression of the primary recrystallized grains. It is presented in (Small) 33-4790. However, the grain-oriented electrical steel sheet produced by this method has a high density of {110} <1> of secondary recrystallized grains, which leads to high magnetic flux density and low iron loss. There is a big disadvantage of the domain. In order to solve this drawback, the micronized technology of oriented electrical steel sheet has been developed. Magnetic micronization technology refers to the method of irradiating the surface of steel sheet in the direction perpendicular to the rolling direction by laser, plasma jet or mechanical method, or by making scratches to refine the magnetic domain to improve iron loss. The method of using Japanese Patent Application Laid-Open No. 58-26405, the mechanical method of Japanese Patent Laid-Open No. 58-5968, and the method of using a plasma jet are disclosed in Japanese Patent Laid-Open No. 62-96617, respectively. Presented. However, in the above methods for minimizing magnetic domains and reducing iron loss, the strains causing magnetic domain minimization are eliminated by stress relief annealing, and the iron loss loss effect disappears. However, there is a disadvantage that can not be used in a stacked core transformer that requires stress relief annealing. A method of indenting one surface of a steel sheet using a gear roll as a micronized micronization technique in which the effect is not extinguished by stress relief annealing is disclosed in Korean Patent Publication No. 90-7448. This method introduces a strain of 90-220 kg / mm2 of average load (total load divided by the area of the deformable part) into the tooth roll and forms fine recrystallized grains by annealing after deformation. It is a technology to refine the magnetic domain by generating a nucleus of new magnetic domain at the grain boundary of the grain and the fine recrystallized grain formed. However, since it is a single-sided indentation, the microcrystal grains are generated only at the indentation surface, and thus the magnetic domain of the indentation opposite surface cannot be miniaturized.

The present inventors have found that the magnetic micronization effect does not disappear even after stress relief annealing when indenting both sides of a steel sheet under a load below the average load disclosed in Korean Patent Publication No. 90-7448 through a mechanical indentation test of a high magnetic flux density oriented electrical steel sheet. In addition, it was found that the iron loss improvement effect is significantly improved compared to the technique disclosed in Korean Patent Publication No. 90-7448.

Therefore, the present invention, unlike the conventional single-sided indentation method in the manufacture of oriented electrical steel sheet, so that the magnetic domain micronization effect is maintained even after the stress relief annealing through the double-sided indentation method, the iron loss is significantly reduced iron loss of oriented electrical steel sheet The purpose is to provide a method.

Hereinafter, the present invention will be described.

According to the invention, by weight% 2-4% Si, 0.02-0.07% C, 0.02-0.04% acid solubility, Al, 0.06-0.08% Mn, 0.02-0.03% S, 60-90 ppm In the manufacturing process of the grain-oriented electrical steel sheet in which the silicon steel containing N and other impurities is insulated and tension-coated by hot rolling, hot-rolled sheet annealing, pickling, cold rolling, decarbon annealing, and high-temperature annealing in a conventional manner, the tension Both sides of the coated plate were rolled with an average load of 60-100kg / mm2 and 45 The method for reducing iron loss by magnetically micronized treatment of a grain-oriented electrical steel sheet which does not disappear even after stress relief annealing, characterized by making a press-in groove having a width of 10-300 μm at intervals of 1-10 mm by press-fitting in a direction perpendicular to This is provided.

Hereinafter, the present invention will be described in detail.

Ash in the process of the present invention is by weight 2-4% Si, 0.02-0.07% C, 0.02-0.04% acid soluble Al, 0.06-0.08% Mn, 0.02-0.03% S, 60-90 ppm Steel slab containing and other unavoidable impurities is insulated and tension coated using a conventional method by hot rolling, hot rolled sheet annealing, pickling, cold rolling, decarbonization annealing, and high temperature annealing. After reheating the steel slab at 1400 ° C for 5 hours, it was hot rolled to 2.3mm thickness, preannealed at 1120 ° C for 2 minutes, pickled, and 0.30-0.23mm thickness was obtained by two cold rolling including one time or intermediate annealing. After cold rolling, in the manufacturing process of a directional electric plate that is decarbonized annealing at 840 ° C. for 3 minutes, followed by MgO coating, high temperature annealing, and tension coating, a steel sheet that has been subjected to high temperature annealing or a steel sheet that has been tension coated is used.

The upper and lower sides of the hot-annealed or tension-coated plate are the average load (the total weight divided by the area subjected to deformation) and the rolling direction with a load of 60-100kg / mm2. Press-fit is performed at intervals of 1-10 mm in the direction perpendicular to the above. De-stressing annealing after indentation reveals recrystallized or recirculated strain at both sides of the steel sheet. By this recrystallized or recovered strain structure, the magnetic domains on both sides of the steel sheet are refined and the iron loss is reduced. The grain-oriented electrical steel sheet manufactured by the present invention has excellent characteristics compared to the single-side indentation technology disclosed in Korean Patent Publication No. 90-7448 because both magnetic domains of both sides are miniaturized.

Fig. 1 shows the iron loss improvement rate when stress-annealed at 850 ° C. for 2 hours after press-fitting both sides of the hot annealing plate in comparison with single-face indentation. In the case of double-sided indentation, an excellent iron loss improvement effect can be obtained compared to single-sided indentation in the load range of 60-100kg / mm2, which is less than 110-190kg / mm2 of single-side indentation.

2 shows the magnetic domains of the upper and lower surfaces of the steel sheet after stress relief annealing at the time of double-sided pressing and single-sided pressing. (a) is a magnetic domain photograph when both surfaces are press-fitted at a load of 80 kg / mm2, and (b) is a magnetic domain photograph when one surface is press-fitted at a load of 130 kg / mm2. In the case of single face indentation (b), the micronization of the indentation surface is obvious, but the micronization of the indentation surface is weak. Increasing the average load clearly shows the micronization to the opposite side of the indentation, but in this case, the orientation of the resulting microrecrystallized grains deviates from the Goss orientation, thus significantly reducing the iron loss improvement rate. In the case of double-sided indentation (a), the finer micronization is apparent on both sides, and thus the iron loss is more pronounced than that of single-sided indentation.

FIG. 3 shows the microstructure after stress relief annealing around the strain introduction portion at the time of double-sided indentation and one-side indentation. (a) is the case where both surfaces were press-fitted with the load of 80 kg / mm <2>, (b) is a photograph when the one surface was press-fitted with the load of 130 kg / mm <2>. In the case of single-sided indentation, recrystallized grains appear around the strain-introduced part, and in the case of double-sided indentation, recrystallized or recovered strain is shown. The recrystallized grains produced are finer than those of single-sided indentation.

Therefore, when the both sides of the grain-oriented electrical steel sheet is press-fitted at a load of 60-100kg / mm 2, the effect is not extinguished by the stress relief annealing, and the magnetic domains on both sides of the upper and lower portions of the steel sheet are miniaturized, thereby making it possible to manufacture the grain-oriented electrical steel sheet having very low iron loss.

EMBODIMENT OF THE INVENTION Hereinafter, the limitation of conditions of this invention is demonstrated.

4 shows the magnetic domain structure by the average load of the double-sided indentation according to the present invention. (a) is a case where a load is 40 kg / lmm <2>, (b) is a case where a load is 80 kg / mm <2>, and (c) is a case where a load is 130 kg / mm <2>. When the load is 60 kg / mm 2 or less, the introduced strain is small, and all of the deformation is eliminated by the stress relief annealing to restore the original domain structure (Fig. 4 (a)). At the load of 60-100kg / mm2, the phenomenon of miniaturization of both domains is clearly seen. (Figure 4 (b)). At loads of 100 kg / mm2 or more, the deformation is so large that the micronized effect due to the deformation of the opposite surface is transferred, resulting in a very complicated magnetic domain structure and an increase in iron loss (Fig. 4 (c)). Therefore, the appropriate range of the load of the present invention is 60-100kg / mm2.

Next, the limitation of the shape of the press-fit groove | channel of this invention method is demonstrated.

If the width of the indentation groove is 10 占 퐉, the magnetic domain does not become fine. In addition, when it is wider than 300㎛, the amount of deformation increases, the magnetic flux density is reduced and iron loss is increased, so should be 10㎛ or more, 300㎛ or less, preferably 60㎛ or more and 120㎛ or less.

If the spacing of the indentation groove is 1mm or less, the amount of deformation increases, so the iron loss is increased. If the thickness of the indentation groove is 10mm or more, the effect of magnetic domain micronization is weak, so 1mm or more and 10mm or less is preferable.

When the angle of the indentation groove is 45 degrees or less with respect to the rolling direction, since the direction of the new magnetic domain generated in the deformation introduction portion is out of the direction for magnetization, the iron loss is rather increased. Do.

The press-fitting method may be any one of gear rolls, knife and steel ball arrangements, and the press-fitting load and the optimum shape need only be obtained.

Hereinafter, the present invention will be described through examples.

Example 1

A silicon steel slab consisting of 3% Si by weight, 0.065% C, 0.027% acid-soluble Al, 0.07% Mn, 0.025% S, 80PPm N and the balance Fe was heated at 1400 ° C. for 5 hours. After hot rolling with a 2.3 mm thick hot rolled sheet, the hot rolled sheet was annealed at 1120 ° C. for 2 minutes, pickled, and cold rolled to 0.30 mm thick. The cold rolled sheet was decarbonized at 840 ° C. for 3 minutes, coated with MgO, and annealed at 1200 ° C. for 20 hours at high temperature. Magnetization of the high-temperature annealed sheet was iron loss (W _17/50) is 1.10W / kg. 120 degrees on both surfaces of high temperature annealing plate With knife in direction of rolling 75 The angle of was pressed in at 5 mm intervals. Table 1 shows the iron loss after tension coating of the steel sheet after indentation and stress relief annealing at 850 ° C. for 2 hours.

TABLE 1

Example 2

A silicon steel slab consisting of 3% Si by weight, 0,065% C, 0.027% acid soluble Al, 0.07% Mn, 0.025% S, 80ppm N and other residues Fe at 2400 ° C. The hot rolled sheet was hot rolled, pickled and cold rolled with a 1,5mm thick cold rolled sheet.

The primary cold rolled sheet was annealed at 1120 ° C. for 2 minutes, cold rolled to a 0.23 mm thick cold rolled plate, and then decarbonized at 840 ° C. for 3 minutes. After decarbonization, high temperature annealing was performed at 1210 ° C. for 20 hours, followed by tension coating.

The edge angle of the tension-coated plate is 120 With knife in direction of rolling 75 At an angle, they were press fitted at intervals of 5 mm. Table 2 shows the characteristics after the stress relief annealing of the steel sheet after the indentation at 850 ° C. for 2 hours.

TABLE 2

Example 3

Edge angle of 90 degrees on both sides of the tension coating plate of the grain-oriented electrical steel sheet prepared as in Example 1 Rolling direction and 75 mm at intervals of 5 mm Indented at an angle.

Table 3 shows the iron loss after tension coating of the steel sheet after the indentation and stress relief annealing at 850 ° C. for 2 hours.

TABLE 3

Example 4

Edge angle of both sides of the tension coating plate of the grain-oriented electrical steel sheet prepared as in Example 2 Rolling direction and 75 mm at intervals of 5 mm Indented at an angle.

Table 4 shows the iron loss after stress relief annealing at 850 ° C. for 2 hours.

TABLE 4

According to the present invention indenting both sides of the grain-oriented electrical steel sheet with an average load of 60-100kg / mm2 from the above embodiment, the magnetic domain micronization effect is maintained even after the stress relief annealing, and the iron loss compared to the conventional micron micronization technique by the single-face indentation method. It can be seen that this remarkably low low iron loss oriented electrical steel sheet can be produced. The grain-oriented electrical steel sheet manufactured by the present invention method can be used in a coil core transformer in which stress removal annealing is essential since the magnetic domain micronization effect is maintained even after stress relief annealing.

Claims (1)

By weight 2-4% Si, 0.02-0.07% C, 0.02-0.04% acid soluble Al, 0.06-0.08% Mn, 0.02-0.03% S, 60-90ppm N, balance Fe and others In the manufacturing process of oriented electrical steel sheet in which the silicon steel containing impurities are insulated and tension coated by hot rolling, hot rolled sheet annealing, pickling, cold rolling, decarbonization annealing, and high temperature annealing in a conventional manner, both sides of the tension coated plate Rolling direction and 45 with an average load of 60-100kg / mm2 Reduction of iron loss due to magnetic micronization of oriented full-rolled steel sheet, which does not disappear even after stress relief annealing, characterized by rolling in a direction perpendicular to the direction of making a press-in groove having a width of 10-300 μm at intervals of 1-10 mm. Way.