JPH02294427A - Production of grain-oriented silicon steel sheet reduced in iron loss - Google Patents

Abstract

PURPOSE:To stably obtain a superior grain-oriented silicon steel sheet reduced in iron loss and free from deterioration in iron loss even if subjected to subsequent stress relief annealing by providing, by means of a pressing device, compressive linear scratches at the prescribed spaces to a cold rolled grain-oriented silicon steel sheet in a direction perpendicular to the sheet surface and then applying decarburizing annealing and finish annealing to the above sheet. CONSTITUTION:Projecting press teeth 2 are allowed to advance and retreat at high speed against a cold rolled grain-oriented silicon steel sheet S in the course of passing by the action of an advance and retreat driving device 3 of a press main body 1 in which the above projecting press teeth 2 orthogonal to the passing direction of the above cold rolled grain-oriented silicon steel sheet S are provided at spaces to apply vertical load to the sheet surface, by which compressive linear scratches are formed at 1-30mm spaces. Subsequently, decarburizing annealing is applied to the above steel, and, after a separation agent at annealing is applied to the above sheet, finish annealing is carried out.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for manufacturing grain-oriented electrical steel sheets with low core loss.

(Prior art) Normally, a grain-oriented electrical steel sheet is produced by hot rolling a silicon steel material containing 4% or less of Sl and annealing the hot rolled sheet as necessary.
A cold-rolled sheet with the final finish thickness is obtained through two or more cold rolling processes with two or more intermediate annealing steps in between, and then decarburization annealing is performed, and then an annealing separator containing MgO as the main component is applied. , final annealing is performed to develop secondary recrystallized grains with Goss orientation,
Furthermore, it is manufactured by removing impurities such as S and N, and forming a glass coating. Furthermore, flattening annealing and insulation coating treatment are performed as necessary.

By the way, in grain-oriented electrical steel sheets, there is a strong desire to improve iron loss characteristics from the perspective of energy conservation.
Studies have been conducted to improve iron loss characteristics, and various methods have been proposed.

As one of the methods for improving the core loss characteristics of grain-oriented electrical steel sheets, it is known to add micro-flaws or distortions to the surface of the steel sheets. For example, there is Japanese Patent Publication No. Sho 5g-5968. This is done by pressing small balls etc. on the surface of the unidirectional electrical steel sheet after final finish annealing to form indentations with a depth of 5μ or less and applying linear microstrain to refine the magnetic domains and cause iron loss. It is a falsification of.

According to this, a material with extremely low iron loss can be obtained.

However, there is a problem in that the iron loss improvement effect disappears if, for example, strain relief annealing is subsequently performed during manufacturing of the wound core.

Magnetic domain refining methods that do not have such problems have been studied and proposed. For example, in JP-A-56-130454, a finish annealed grain-oriented electrical steel sheet is subjected to complex linear strain using a knife, razor blade, diamond sand, gear roll, shot, laser, etc., and then heated to a temperature of 700°C or higher. Heating is used to generate fine recrystallized grain groups in the strain-introduced region to reduce iron loss.

Furthermore, in Japanese Patent Application Laid-open No. 131-117218, 90 to 220 kg of finish-annealed grain-oriented electrical steel is coated with a toothed roll in a range of 45 degrees from perpendicular to the rolling direction.
After applying a load of /mJ and creating groove-shaped flaws, it was heated to 750'C.
A method for manufacturing a grain-oriented electrical steel sheet with low core loss by performing the heat treatment as described above is described.

According to these, even if strain relief annealing is performed afterward, the iron loss improving effect is not lost, and magnetic domain refinement is performed, which has a certain effect and contributes to improving the magnetic properties.

Furthermore, a method for reducing iron loss by introducing linear flaws into a steel sheet before final annealing has been proposed in Japanese Patent Application Laid-Open No. 197520/1983. This uses a knife edge, laser, electric discharge machining, and electron beam to create linear scratches with a width of 3oo! M or less, depth l00u
The steel sheets are rolled in a direction perpendicular to the rolling direction with a spacing of 1 or more, and then finish annealed to reduce iron loss.

This will also provide some effect.

By the way, in order to perform magnetic domain refining in which the iron loss reduction effect does not disappear during strain relief annealing, it is important to locally apply linear flaws with large strain at intervals to the steel sheet. In grain-oriented electrical steel sheets, temperature deviations within the coil during annealing, especially differences in heating and cooling rates, cause shape defects such as center bulges and side distortions, and the linear flaws can be industrially stabilized over the entire width of the steel sheet. Difficult to grant.

In addition, since a ceramic-like glass coating is formed on the surface of the steel sheet, linear flaw imparting devices such as gear rolls and micro-projection rolls embedded with high hardness materials such as diamonds are subject to severe wear and iron loss during strain relief annealing. It is difficult to provide the above-mentioned linear flaws, whose reduction effect does not disappear, to grain-oriented electrical steel sheets over a long period of time.

In addition, before final annealing, grain-oriented electrical steel sheets, especially cold-rolled sheets, are extremely hardened, so the gear rolls and micro-protrusion rolls are easily worn, and the amount of steel sheet that can be provided with the linear flaws is small. It is necessary to frequently polish the tip of the roll and minute protrusions, and it is also necessary to replace the roll with a new one, resulting in problems such as deterioration of workability and productivity, and further increase in cost.

In addition, in the case of laser treatment, the absorption rate of the laser beam to the steel plate is about 1/4 smaller when treating the steel plate after cold rolling than when treating the steel plate with a coating on the surface after finish annealing. Therefore, large-capacity laser irradiation equipment is required.

Other types of knives, razor blades, etc. are grain-oriented electrical steel sheets with low iron loss, which can be industrially and easily applied to a large number of steel sheets and over the entire width of the steel sheet by applying linear flaws that subdivide magnetic domains without loss. stably and (〒, %, %−νζ(!'
? A load perpendicular to the plate is instantaneously applied to a cold-rolled %I21 electrical steel plate using a press to create compression linear flaws on one or both sides of the steel plate at intervals of 1 to 30 degrees, and then A method for producing a grain-oriented electrical steel sheet with low iron loss characterized by decarburization annealing and finish annealing.

The present invention will be explained in detail below.

The present inventors conducted research experiments on the industrially superior formation of linear flaws that perform magnetic domain refining without eliminating the iron loss reduction effect by strain relief annealing.

As a result, when a grain-oriented electrical steel sheet is subjected to a high-speed load perpendicular to the sheet surface using a press, compression linear flaws with large strain and locally concentrated in the thickness direction are formed. We have determined that this is the case.

Furthermore, if compression linear flaws are formed by pressing when the grain-oriented electrical steel sheet is a cold-rolled sheet, the forming operation causes less wear on the press teeth, and can be performed on a large quantity of grain-oriented electrical steel sheets. The compression linear flaw becomes sharp in the plate thickness direction, and due to the synergistic effect of this feature and the formation of a glass film in the flawed area during the subsequent finish annealing, iron loss is low and strain relief annealing is possible. It has been found that a grain-oriented electrical steel sheet can be obtained that does not lose its effect even if the effect is not lost.

According to this method, the brace teeth can be manufactured only by straight line machining, and carbide can be used as the material, so sharp compression linear flaws with large distortion can be introduced into the grain-oriented electrical steel sheet after cold rolling. be able to. In addition, since impact force is involved, the force required to introduce the flaw can be small, so workability is good and the process can be carried out stably.

In the present invention, compression linear flaws are applied at intervals to a grain-oriented electrical steel sheet after cold rolling by pressing, but it is necessary to specify the steel composition and manufacturing conditions until the formation of compression linear flaws in the grain-oriented electrical steel sheet. There isn't.

That is, for example, Afi N, MnS as an inhibitor.
, MnSe, BN, Cu2S, etc. are used as appropriate. In addition, Cu, Sn, Cr, Ni, Mo, Sb,
It contains elements such as W, and is hot-rolled, annealed, and cold-rolled once or twice or more with an intermediate annealing step in between to obtain the final thickness.

Thereafter, compression linear flaws are applied using a press device as shown in FIG. In the drawing, a cold-rolled grain-oriented electrical steel sheet is threaded in the direction of the arrow. Reference numeral 1 denotes a press body, and at the bottom thereof, protruding press teeth 2 that are substantially orthogonal to the sheet passing direction are provided at intervals.

The press tooth 2 advances and retreats at high speed against the grain-oriented cold-rolled electrical steel sheet S during sheet passing by the action of the advance/retreat drive device 3, applies a load perpendicular to the sheet surface, and forms compression linear flaws.

The brace tooth 2 has a second tooth tip shape so that the compression linear flaw can be stably formed on the cold-rolled grain-oriented electrical steel plate S over a long period of time, and it can be easily polished when it wears out.
As shown in the figure, it is preferable to have a straight tooth shape 2-1 and a wedge-shaped cross section.

Further, it is preferable that the press tooth 2 is made of a super hard material such as a super hard metal or ceramic, but since the shape of the tooth tip is as described above, the production is easy. 4 is a rolling force control mechanism, which controls the rolling load. 5 is a mold, 6 is a pedestal, and 7 is a feed roll.

The steel plate provided with compression linear flaws is then decarburized and annealed, coated with an annealing separator, and then finish annealed.

By the way, as shown in Fig. 3, the compression linear flaws A formed on the grain-oriented electrical steel cold-rolled sheet S by pressing are sharper in the thickness direction than the linear flaws B formed by gear rolls. Therefore, iron loss is reliably reduced and stable.

In addition, since there is no glass coating on the surface of the steel sheet and lubrication is easy, there is less wear on the press teeth 2 when forming compression linear flaws, and a large amount of cold-rolled grain-oriented electrical steel sheet is coated with iron by strain relief annealing. The compression linear flaw can be stably formed without losing its loss reduction effect.

A grain-oriented electrical steel cold-rolled plate according to the present invention was pressed to a length of 5 m.
Compression linear flaws are formed in the direction orthogonal to the rolling direction at m intervals, then decarburized annealed, coated with an annealing separator containing MgO as the main component, and finish annealed at 1200°C. The iron loss characteristics were investigated.

After that, strain relief annealing was performed at 900° C. to examine iron loss characteristics, and the results are shown in FIG.

The comparative example is a grain-oriented electrical steel sheet that has been finish annealed at 1200° C., and is provided with micro-flaws at 10 mm intervals in a direction orthogonal to the rolling direction by laser irradiation.

The test material contained 3.2796 S1 and had a thickness of 0.2
It is a 3m+s grain-oriented electrical steel sheet.

As can be seen from FIG. 4, according to the present invention, even when strain relief annealing is performed, there is no deterioration in iron loss and a low iron loss material can be obtained.

In addition, when applying compression linear flaws by pressing, if a plurality of press teeth 2 are provided at intervals, the grain-oriented electrical steel cold-rolled sheet S is simultaneously compressed by a plurality of press teeth 2. Since it is subjected to a load, strain is applied in a restrained state.

For this reason, no shape change occurs in the steel plate, and compression linear flaws are uniformly formed over the entire width of the plate.

The compression linear flaws are applied at intervals, and if the intervals become narrower, the effect of subdividing the magnetic domains will be reduced and the magnetic flux density will be lowered, so it is set to 1IDI1 or more. On the other hand, if the interval becomes too wide, the effect of subdividing the magnetic domains will be reduced in this case as well, so it is set to 30n++* or less.

The direction of the compression linear flaw is preferably 90" to 45" with respect to the rolling direction of the grain-oriented electrical steel sheet, and the width of the strain is 5
It is preferable to set it to 300-.

In addition, the load for applying compression linear flaws is 3 to 30 kg/kg from the viewpoint of workability and prolonging the life of the press equipment.
1111 is preferred.

Note that after forming the compression linear flaws, decarburization annealing and final annealing are performed as described above, but it is of course possible to apply an insulating film coating liquid to the steel plate after that to form an insulating film.

(Example) C: 0.083, Si: 3.10, M in weight%
n: 0.07B, A47: 0.028, S: 0
．． 021, Cu:0.08SSn:0. A silicon steel slab consisting of lO balance iron was hot rolled, annealed, and cold rolled by a well-known method to obtain a steel plate with a thickness of 0.2201 m.

Compression linear flaws were applied to the obtained grain-oriented electrical steel cold-rolled sheet using a press in which 20 protruding teeth were provided at 7 ms intervals perpendicular to the steel sheet rolling method.

Next, the well-known steps of decarburization annealing, annealing, application of a separating agent, and final finish annealing were performed. The obtained steel plate was used as a test shrine "after treatment". Furthermore, some steel plates are annealed at 800℃.
x 2 hours, and the test material was obtained as "after strain relief annealing". For comparison, a silicon steel slab with the same steel composition was used, and the cold-rolled plate did not form any compression linear flaws, and the subsequent treatments were finish annealed in the same manner as the "untreated" test material. . In addition, the steel plate was irradiated with a laser in a direction perpendicular to the rolling direction at intervals of lOm+s to obtain a "after laser treatment" test material, and was further subjected to strain relief annealing at 800°C for 2 hours to obtain a "after laser treatment and strain relief annealing". It was used as a sample material.

These iron loss (W') and magnetic flux density (B8)17
/50 measurement results are shown in Table 1.

(Effects of the Invention) According to the present invention, it is possible to stably obtain an extremely excellent grain-oriented electrical steel sheet with low iron loss and no deterioration in iron loss even if it is subsequently subjected to strain relief annealing.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram of a press device for forming compressed linear flaws in one embodiment of the present invention, Fig. 2 is a perspective view of a press tooth in one embodiment, and Fig. 3 is an o). (B) is an explanatory diagram of the cross-sectional shape of a compression linear flaw in one embodiment, and FIG. 4 is a chart showing stress relief annealing for iron loss in one embodiment. Agent Patent Attorney Tatsuo Chanoki Figure 2 Figure 3

Claims (1)

[Claims] A load perpendicular to the plate surface is applied at high speed to a cold-rolled grain-oriented electrical steel sheet using a press to create 1 to 3 compression linear flaws.
A method for producing a grain-oriented electrical steel sheet with low iron loss, characterized by forming the steel sheet at intervals of 0 mm, followed by decarburization annealing and final annealing.