JPH01156426A - Manufacture of directional magnetic steel plate having low iron loss - Google Patents

Abstract

PURPOSE:To stably manufacture the title steel plate by forming compressive linear strains at specific intervals only by vertical loads by a press or the plate surface of the directional electromagnetic steel plate and annealing. CONSTITUTION:The directional magnetic steel plate S subjected to finish annealing by a feed roll 7 is passed to the main body 1 of the press and the plate surface is provided with the loads vertical thereto by the high-speed movement of a forwardly or backwardly driving apparatus 3 in the use of plural projected teeth 2 to form compressive linear strains 8. At this time, the intervals of the strains 8 are regulated to 1-30mm, the direction in the strains 8 is regulated to about 90-45 deg. against the rolling direction, its width is regulated to about 10-300mu and the loads to be applied are preferably regulated to about 3-20kg/mm. By this method, the compressive linear strains 8 can uniformly be formed over the whole of the plate width; and when annealed at about >=750 deg.C, newly recrystallized grains are generated in the direction of the plate thickness onto the strain part 8-1 and the fining of its magnetic domain is executed. In this way, the directional magnetic steel plate S having low iron loss is stably manufactured at low cost.

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 Si, 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 film. 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, a method of imparting micro-bottoms or distortion to the surface of the steel sheet is known. For example, there is Japanese Patent Publication No. 5B-5968. This is done by pressing small balls etc. onto 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 reduce iron loss. It is something that can be improved. According to this, a material with extremely low iron loss can be obtained.

However, there is a problem in that the effect of improving iron loss 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 Japanese Patent Application Laid-open No. 56-130454, knives, razor blades,
Linear complex strain is applied using metal sand, gear rolls, shot, laser, etc., and then heated to a temperature of 700°C or higher to generate fine recrystallized grain groups in the strain-introduced region, which reduces iron loss. It is being

In addition, Japanese Patent Application Laid-open No. 61-117218 discloses that the surface of a finish annealed grain-oriented electrical steel sheet is
A method is described for producing a low iron loss grain-oriented electrical steel sheet by applying a load of 90 to 220 kg/- with a toothed roll in the range of 100°C to provide a grooved bottom, and then heat-treating at 750°C or higher. There is.

According to these, even if strain relief annealing is performed afterwards, magnetic domain refining is performed that does not eliminate the iron loss improving effect, and has a certain effect and contributes to improving the magnetic properties.

[Problems to be solved by the invention] By the way, regarding the improvement of the magnetic properties of grain-oriented electrical steel sheets,
This is no longer sufficient, and users are demanding further improvements. Furthermore, regarding the magnetic domain refining method, it is important to stably impart microstrains to the steel sheet over the entire width direction at the lowest possible cost.

An object of the present invention is to stably and inexpensively produce a grain-oriented electrical steel sheet with low core loss, which is subjected to magnetic domain refining without losing its core loss improving effect through strain relief annealing.

[Means for solving problems]

The present inventors conducted various experiments in order to achieve the above object, and found that when compressive linear strain is formed at intervals using only a load perpendicular to the surface of a grain-oriented electrical steel sheet using a press, It was found that strain was strongly introduced in the thickness direction of the sheet, and the subsequent annealing produced a strong magnetic domain refining effect, resulting in a significant reduction in iron loss compared to when strain was applied with the same load as in the conventional method. Further, since only a small force is required to impart strain, workability is good and the process can be carried out stably.

The present invention will be explained in detail below.

In the present invention, compressive linear strain is applied at intervals by pressing to a grain-oriented electrical steel sheet before or after final annealing. does not need to be specified. That is, for example, eight I! as an inhibitor! , L MnS, MnSe,
BN+CuzS etc. are used as appropriate.

In addition, Cu, Sn, Cr, Ni, M
Contains elements such as O, Sb, and W, and is hot rolled and annealed once, or cold rolled two or more times with an intermediate annealing step to achieve the final thickness, decarburized, and then annealed. A separating agent is applied and finish annealing is performed.

In this example, a case will be described in which compressive strain is applied to a finish annealed grain-oriented electrical steel sheet.

A grain-oriented electrical steel sheet is subjected to compressive linear strain using a press device as shown in FIG. In the drawing, S is a grain-oriented electrical steel sheet that is threaded in the direction of the arrow. Reference numeral 1 denotes a press main body, and projecting teeth 2 substantially perpendicular to the sheet passing direction are provided at intervals on the lower part of the press main body. The projecting teeth 2 move forward and backward at high speed against the grain-oriented electromagnetic steel sheet S that is being passed through by the action of the advance/retreat drive device 3, and apply a load perpendicular to the sheet surface to form a compressive linear strain. 4 is a rolling force control mechanism, which controls the rolling load. 5 is a mold, and 6 is a pedestal. Further, 7 is a feed roll.

By the way, the grain-oriented electromagnetic steel sheet S is
When a compressive linear strain 8 is applied to the plate by applying a load only perpendicular to the plate surface, the strained portion 8-1 is concentrated and strongly introduced in the plate thickness direction, as shown in Fig. 2. I found out.

Compressive linear strain was applied at five-value intervals by changing the rolling force load, and then annealing was performed to investigate iron loss characteristics. The test material was a finish-annealed grain-oriented electrical steel sheet containing 3.20% St and having a thickness of 0.220 mm. The result is the third
The figure also shows a stepped roll with linear strain applied at the same intervals.

As is clear from this figure, it was found that when compressive linear strain was applied, the rolling load was small, the magnetic domain refining effect was achieved, and the iron loss was low.

In addition, when applying compressive linear strain by pressing, the protruding teeth 2
If a plurality of such protrusions are provided at intervals, the grain-oriented electromagnetic steel sheet S receives a compressive load from the plurality of protruding teeth 2 at the same time, so that strain is applied in a restrained state. For this reason, the steel plate does not undergo any shape change, and compressive linear strain is uniformly formed over the entire width of the plate.

Compressive linear strain is applied at intervals, and if the intervals become narrower, the effect of subdividing the magnetic domains will decrease and the magnetic flux density will decrease, so the interval is set to 1 m or more. On the other hand, if the spacing becomes too wide, the effect of subdividing the magnetic domains will be reduced in this case as well, so it is set to 30 mm or less.

The direction of the compressive linear strain is preferably 90 degrees to 45 degrees with respect to the rolling direction of the grain-oriented electrical steel sheet, and the width of the strain is 1
It is preferable to set it as 0-300 micrometers.

In addition, the load for applying compressive linear strain is 3 to 20 kg/m from the viewpoint of workability and prolonging the life of the press equipment.
II+ is preferred.

After applying compressive linear strain, it is annealed at 750°C or higher. By this annealing, new recrystallized grains are generated in the compressive linear strain portion in the thickness direction, and the magnetic domains are refined. For this purpose, it is necessary to carry out the process at 750°C or higher. This annealing can be performed in combination with annealing in which an insulating film coating liquid is applied to the steel plate and baked.

When applying compressive linear strain before final annealing, it is desirable to apply compressive linear strain to a steel plate that has been cold rolled to the final thickness and then decarburized and annealed. Similar effects can be obtained in this case as well.

〔Example] Examples will be described below.

Example 1 C: 0.083, Si: 3.27, M in weight %
n: 0.076, Af: 0.028, S: 0.02
A silicon steel slab consisting of 1, Cu: 0.15, Sn: 0.15 and balance iron was hot rolled, annealed and cold rolled by a well-known method to obtain a steel plate having a thickness of 0.220 mm.

Next, the well-known steps of decarburization annealing, application of an annealing separator, and final finish annealing were performed. Compressive linear strain was applied to the obtained steel plate using a press having 20 protruding teeth arranged at 5-hole intervals perpendicular to the rolling direction of the steel plate at a reduction blade of 11 kg/mm.

Next, annealing was performed at 800″CX for 2 hours, and “after treatment”
This was used as the sample material. In addition, for comparison, heat flattening annealing was performed after finish annealing at ao o "c" and "untreated"
This was used as the sample material. The magnetic properties of each were measured and the results are shown in Table 1. w+? /s. is iron loss (W/kg)
,B. is the magnetic flux density (T).

Table 1 Example 2 Weight % TeC: 0.082, St: 3.25, M
n: 0.074, //! :0.027, S:0.0
22, Cu:0.10. A silicon steel slab consisting of Sn: 0.08 and balance iron was hot rolled, annealed and cold rolled by a well-known method to obtain a steel plate having a body thickness of 0.220.

Next, the well-known decarburization annealing was further performed.

Thereafter, compressive linear strain was applied to the steel plate using a press having 20 protruding teeth at 5 mm intervals perpendicular to the rolling direction of the steel plate using a rolling blade of 6 kg/M.

Next, apply annealing material and finish annealing at 1200℃,
After that, an insulating film coating liquid is applied, and the insulating film is baked by annealing at 880°, which also serves as processing and heat flattening.
C, and it was used as a "post-treated" test material. For comparison, after the decarburization annealing without applying compressive linear strain by the press, the above-mentioned finish annealing and film baking were performed by annealing that was both a treatment and a heat flattening, and the "untreated" This was used as the sample material. The magnetic properties of each were measured and the results are shown in Table 2. W+? /S. is iron loss (W/kg),
B1° is the magnetic flux density (T).

Table 2 (Effects of the Invention) As is clear from the above examples, according to the present invention, grain-oriented electrical steel sheets with low core loss can be stably manufactured at low cost.

In addition, even if the obtained grain-oriented electrical steel sheet is subsequently subjected to strain relief annealing that is performed during the manufacture of the wound core, no deterioration in iron loss occurs at all.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing a press for applying compressive linear strain in one embodiment of the present invention, Fig. 2 is a diagram showing compressive linear strain for detailed explanation of the present invention, and Fig. 3 is a diagram showing a press for applying compressive linear strain. FIG. 3 is a diagram showing the relationship between iron loss value and rolling load for applying compressive linear strain in an experimental example in the present invention. Fig. 2 Fig. 3 Rolling load (KV/n)

Claims (1)

[Claims] A grain-oriented electrical steel sheet with low core loss characterized by forming compressive linear strains at intervals of 1 to 30 mm by pressing only a load perpendicular to the plate surface, and then annealing the grain-oriented electrical steel sheet. manufacturing method.