JPH0663037B2 - Method for producing grain-oriented electrical steel sheet with low iron loss - Google Patents

Description

The present invention relates to a method for producing a grain-oriented electrical steel sheet with low iron loss.

[Conventional technology]

Usually, grain-oriented electrical steel sheets are obtained by hot rolling a silicon steel material containing Si: 4% or less, annealing the hot-rolled sheet if necessary, and cold-rolling it once or twice with intermediate annealing. A cold-rolled sheet with a final finished thickness is obtained by the rolling process, and then decarburization annealing is performed, and then an annealing separating agent containing MgO as a main component is applied, and finish annealing is performed to obtain a secondary regrind having a Goss orientation. It is manufactured by expressing crystal grains, removing impurities such as S and N, and forming a glass film. Further, if necessary, flattening annealing and insulating coating treatment are performed.

By the way, in the grain-oriented electrical steel sheet, it is strongly demanded to improve the iron loss characteristics from the viewpoint of energy saving,
Studies have been conducted to improve the 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 microscopic flaws or strains to the surface of the steel sheet is known. For example, there is Japanese Patent Publication No. 58-5968. This is because the small spheres etc. are pressed on the surface of the unidirectional electrical steel sheet after the final finish annealing to form a dent with a depth of 5μ or less and a minute linear strain is applied to subdivide the magnetic domain to reduce iron loss. To improve. According to this, a material having extremely low iron loss can be obtained. However, there is a problem that the iron loss improving effect disappears when the stress relief annealing is performed thereafter, for example, when manufacturing the wound core.

A magnetic domain subdivision method that does not have such a problem has been studied and proposed. For example, in JP-A-56-130454, finish-annealed grain-oriented electrical steel sheet, knife, razor blade, hard sand,
A linear complicated strain is given by a gear roll, a shot, a laser, etc., and then heated to a temperature of 700 ° C. or higher to generate a group of fine recrystallized grains in a strain introduction region to reduce iron loss.

Further, JP-A-61-117218 discloses that a surface of a grain-finished grain-oriented electrical steel sheet is subjected to a load of 90 to 220 kg / m ^{2 by} a tooth profile roll within a range of 45 ° from a right angle to the rolling direction to form a groove shape. It describes a method for producing a low iron loss grain-oriented electrical steel sheet by applying a flaw and then heat-treating at 750 ° C. or higher.

According to these, even if the stress relief annealing is subsequently performed, the iron loss improving effect is such that the magnetic domain is subdivided so that the iron loss improving effect is not crystallized, and it has a certain effect and contributes to the improvement of the magnetic characteristics.

[Problems to be solved by the invention]

By the way, regarding the improvement of magnetic properties of grain-oriented electrical steel,
This is not enough anymore, and users are demanding further improvement. In addition, it is important for the method of subdividing the magnetic domains to impart a minute strain at the lowest possible cost and stably over the entire width direction of the steel sheet.

An object of the present invention is to stably and inexpensively manufacture a grain-oriented electrical steel sheet having a low iron loss, in which magnetic domain subdivision in which the iron loss improving effect is not lost by strain relief annealing is performed.

[Means for solving problems]

As a result of performing various experiments to achieve the above-mentioned objects, the present inventors formed a compression linear strain at intervals with a force of only a load in a direction perpendicular to the plate surface of the grain-oriented electrical steel sheet by pressing, It was found that the strain is strongly introduced in the plate thickness direction, the magnetic domain refinement action appears strongly in the subsequent annealing, and the iron loss is significantly reduced as compared with the case where the strain is applied under the same load as the conventional method. Further, since the force required to impart the strain may be small, workability is good and stable operation can be performed.

The present invention will be described in detail below.

The present invention, for the grain-oriented electrical steel sheet before or after finish annealing, applies a compression linear strain at intervals with a press, but the grain-oriented electrical steel sheet is a steel component and manufacturing conditions until the compression linear strain is applied. Need not be specified. That is, for example, AlN, MnS, MnSe, BN, Cu ₂ S or the like is appropriately used as the inhibitor. In addition, if necessary, elements such as Cu, Sn, Cr, Ni, Mo, Sb, W are contained, and hot rolled and annealed once or two or more times with an intermediate annealing step between cold It is rolled to a final thickness, decarburized and annealed, and an annealing separator is applied to finish annealing.

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

Compressive linear strain is applied to the grain-oriented electrical steel sheet by a pressing device as shown in FIG. In the drawings, S is a grain-oriented electrical steel sheet which is threaded in the direction of the arrow. Reference numeral 1 is a press body, and projecting teeth 2 which are substantially orthogonal to the sheet passing direction are provided at a lower portion of the press body at intervals. The projecting teeth 2 advance and retreat at high speed with respect to the grain-oriented electrical steel sheet S in the passing plate by the action of the advancing / retreating drive device 3 and apply a vertical load to the plate surface to form a compression linear strain. Reference numeral 4 denotes a rolling force control mechanism, which controls the rolling load. Reference numeral 5 is a mold, and 6 is a pedestal. Further, 7 is a feed roll.

By the way, the grain-oriented electrical steel sheet S is pressed by the protruding teeth 2 by pressing.
As shown in FIG. 2, the strained portion 8-1 is concentrated and strongly introduced in the plate thickness direction by applying a compressive linear strain 8 with a load only in the direction perpendicular to the plate surface. I found him.

The rolling force load was changed to apply a compressive linear strain at 5 mm intervals, and then annealing was performed to investigate the iron loss characteristics. The test material is a grain-finished grain-oriented electrical steel sheet containing 3.20% Si and having a thickness of 0.220 mm. The results are shown in FIG. 3 together with the stepwise rolls having linear strains applied at the same intervals.

As is clear from this figure, it was found that those to which the compressive linear strain was applied exhibited a magnetic domain refining action with a reduced rolling load and a low iron loss.

When a compressive linear strain is applied by pressing, the protruding teeth 2
When a plurality of the grain-oriented electrical steel sheets S are provided at intervals, the grain-oriented electrical steel sheet S is subjected to a compressive load by the plurality of projecting teeth 2 at the same time, so that strain is applied in a restrained state. For this reason, the shape of the steel sheet does not change, and the compressive linear strain is uniformly formed over the entire width of the sheet. The depth of linear strain needs to be more than 5 μm. Depth of linear strain is 5μ
When it is m or less, the strain disappears by annealing, and new recrystallized grains are not generated in the linearly strained portion.

The compressive linear strain is applied at intervals, but if the intervals are narrowed, the effect of subdividing the magnetic domains is reduced, and the magnetic flux density is reduced, so it is set to 1 mm or more. On the other hand, if the distance is too wide, the effect of subdividing the magnetic domains is reduced in this case as well, so the distance is set to 30 mm or less.

The direction of the compressive linear strain is preferably 90 to 45 degrees with respect to the rolling direction of the grain-oriented electrical steel sheet, and the strain width is 1
The thickness is preferably 0 to 300 μm.

Further, the load for imparting the compressive linear strain is preferably 3 to 20 kg / mm from the viewpoint of workability or prolongation of the life of the press machine.

After applying the compressive linear strain, annealing is performed at 750 ° C. or higher. By this annealing, new recrystallized grains are generated in the compression linear strain portion in the plate thickness direction, and the magnetic domains are subdivided. For this purpose, it is necessary to carry out at 740 ° C. or higher. This annealing can be performed in combination with the annealing in which the insulating coating solution is applied to the steel sheet and baked.

When a compressive linear strain is applied before finish annealing, it is desirable to perform decarburization-annealed steel sheet after cold rolling to the final sheet thickness. In this case as well, the same operational effect is obtained.

〔Example〕

 Examples will be described below.

Example 1 C: 0.083, Si: 3.27, Mn: 0.07 by weight%
6, Al: 0.028, S: 0.021, Cu: 0.15,
Sn: 0.15 A silicon steel slab consisting of the balance iron is subjected to hot rolling-annealing-cold rolling by a well-known method and then 0.220 mm.
A thick steel plate was obtained.

Next, the well-known decarburization annealing-annealing separation agent application-final finishing annealing steps were carried out. A compressive linear strain was applied to the obtained steel sheet by a press provided with 20 projecting teeth at intervals of 5 mm perpendicularly to the rolling direction of the steel sheet with a rolling force of 11 kg / mm.

Then, annealing was performed at 800 ° C. for 2 hours to obtain a “after treated” sample material. For comparison, heat flattening annealing after finish annealing was performed at 800 ° C. to obtain an “untreated” test material. The respective magnetic properties were measured, and the results are shown in Table 1. W _17/50 is iron loss (W / kg), and B ₁₀ is magnetic flux density (T).

Example 2 C: 0.082, Si: 3.25, Mn: 0.07 by weight%
4, Al: 0.027, S: 0.022, Cu: 0.10.
Sn: 0.08 A silicon steel slab consisting of the balance iron is hot-rolled-annealed-cold-rolled by a known method to 0.220 mm.
A thick steel plate was obtained.

Then, further well-known decarburization annealing was performed.

Thereafter, a compression linear strain was applied by a pressing force of 6 kg / mm, which was provided with 20 projecting teeth at intervals of 5 mm orthogonal to the rolling direction of the steel sheet.

Then, an annealing separator is applied and finish annealing is performed at 1200 ° C, then an insulating film coating solution is applied and annealing is performed at 880 ° C for both insulating film baking treatment and heat flattening. And Further, for comparison, without giving a compressive linear strain to the press well,
After decarburization annealing, the above-mentioned finish annealing, film baking treatment and heat flattening annealing were performed together to obtain an "untreated" sample material. The magnetic properties were measured, and the results are shown in Table 2. W _17/50 is iron loss (W / kg), and B ₁₀ is magnetic flux density (T).

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

Further, the obtained grain-oriented electrical steel sheet is not deteriorated in iron loss at all even if it is subsequently subjected to strain relief annealing which is carried out during the production of the wound core.

[Brief description of drawings]

FIG. 1 is a diagram showing a press for imparting a compressive linear strain in one embodiment of the present invention, FIG. 2 is a diagram showing the compressive linear strain for explaining the operation of the present invention, and FIG. It is a figure which shows the relationship between the iron loss value and the rolling load which gives a compressive linear strain in one experimental example in this invention.

Claims (1)

[Claims] 1. A linear compression sheet having a depth of more than 5 μm is formed at intervals of 1 to 30 mm on a grain-oriented electrical steel sheet by pressing only in a direction perpendicular to the sheet surface, and then annealed to obtain a compression linear sheet. A method for producing a grain-oriented electrical steel sheet with low iron loss, which comprises generating new recrystallized grains in a strained portion.