JPH05279740A - Method for manufacturing high-silicon non-oriented electrical steel sheet with extremely excellent magnetic properties - Google Patents

Abstract

(57) [Abstract] [Purpose] The optimum cold rolling rate is specified when a high silicon non-oriented electrical steel sheet is produced using a cast steel strip solidified by a moving and renewing cooling body surface. [Structure] 4.0% <Si ≤ 8.0 wt%, Al ≤ 2.0
In the process of solidifying the wt% high silicon non-oriented electrical steel sheet with the moving and renewing surface of the cooling body, pickling, cold rolling and finish annealing, the cold rolling rate is 5% or more and 40% or more.
Less than When the cold rolling ratio is relatively low,
The texture of the product sheet after finish annealing is sharpened by that of columnar crystals. According to this method, a textured random cube ({100} that can be said to be ideal for non-oriented electrical steel sheets)
<0vw>) is obtained with the product plate. [Effects] According to this method, a high-silicon non-oriented electrical steel sheet having extremely excellent magnetic properties can be obtained, which can be a new product.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a high-silicon non-oriented electrical steel sheet having extremely high magnetic flux density and low iron loss.

[0002]

2. Description of the Related Art In recent years, demands for quality improvement of non-oriented electrical steel sheets as magnetic core materials for rotating machines have become stronger from the viewpoint of energy saving. In order to meet this demand, the manufacturers of electromagnetic steel sheets are also conducting research and development to improve the magnetic properties of non-oriented electrical steel sheets, and industrially, a number of them are specified in JIS. Non-oriented electrical steel sheets are manufactured.

In the manufacturing process of non-oriented electrical steel sheets, in order to obtain a product having a low iron loss value, conventionally, the steel is highly purified in its melting stage, the Si content in the steel is increased, and the finishing is performed. Means such as sufficient temperature and time have been adopted in the annealing, but the conventional S
The upper limit of the content of i was specified to be 4%.

However, when these technical means are used, the iron loss value of the product is low, but there is a problem that the magnetic flux density is low from the viewpoint of texture. Also, S
When i is high as in the claims, in the usual manufacturing method,
In the steps after hot rolling, workability is not practical due to brittleness. In order to overcome this difficulty, methods such as warm rolling and silicon immersion treatment have been devised.

On the other hand, in recent years, a method of solidifying by a moving and renewing surface of a cooling body has been developed and is beginning to be applied to the field of non-oriented electrical steel sheets. But so far,
The Si% was 4% by weight or less, and the cold rolling ratio was 40% or more. When the cold rolling reduction ratio is 40% or more, the texture after the final finish annealing has a surface index parallel to the steel sheet surface of {10.
Not only 0} but also the {111} plane is quite strong,
In particular, there was a limit to the improvement of magnetic flux density.

[0006]

SUMMARY OF THE INVENTION The present invention is to solve the above-mentioned problems in the prior art. In order to compensate for and further improve the decrease in magnetic flux density due to high Si, the surface of the cooling body is renewed by moving. It is an object of the present invention to provide a manufacturing method capable of supplying a high-silicon non-oriented electrical steel sheet having a low iron loss in all circumferential directions and an extremely high magnetic flux density by adopting a steel strip casting method for solidifying into ..

[0007]

Means for Solving the Problems The inventors of the present invention have made intensive studies and found that when the Si content exceeds 4% by weight and the cold rolling reduction is less than 40, excellent magnetic properties are obtained. The non-oriented electrical steel sheet manufacturing method with has been found out. That is, the present invention is based on such knowledge, and the characteristic feature thereof is that, in% by weight, 4.0% <Si ≦ 8.0.
%, Al ≦ 2.0% of molten steel (so-called non-transformed steel) is solidified by a moving and renewing surface of a cooling body to form a cast steel strip, and then the cast steel strip is cold-rolled to a predetermined thickness. In the manufacturing method of the non-oriented electrical steel sheet that is finish-annealed after the final (thickness), the magnetic properties that make the rolling ratio 5% or more and less than 40% (preferably less than 30%) during cold rolling are extremely high. This is a method of manufacturing an excellent high-silicon non-oriented electrical steel sheet.

The present invention will be described in detail below. The inventors, as a result of repeated intensive studies to solve the technical problem in the present invention, directly obtain a casting ribbon from molten steel, by appropriately taking the cold rolling rate thereafter, after finish annealing We were able to control the texture in the product, and succeeded in obtaining a non-oriented electrical steel sheet with extremely high magnetic flux density and good iron loss (low iron loss value).

First, the component system will be explained. For the purpose of improving the mechanical properties of the product, improving the magnetic properties, rust resistance, etc., or for other purposes, Mn, P, B, Ni, Cr, S.
The effect of the present invention is not impaired even if one, two or more kinds of b, Sn and Cu are contained. The present invention also includes the following components. If C is 0.050% or less, the object of the present invention can be achieved. Applications of non-oriented electrical steel sheets are
It is mainly a rotating machine, and from the viewpoint of stable magnetic characteristics,
It is required that the deterioration of the magnetic properties (magnetic aging) does not occur during the use of the non-oriented electrical steel sheet. S is an element that is inevitably mixed during the melting stage of steel and is combined with Mn to form MnS during cooling after solidification, so 0.0100%
Should be: N may be 0.010% or less. Like S, when N solidifies rapidly due to the moving and renewing surface of the cooling body, N forms a solid solution in the steel strip and forms precipitates such as AlN and MnS during cooling, and recrystallized grains during finish annealing. And the so-called pinning effect that hinders the movement of the magnetic domain wall when the product is magnetized and becomes a factor that hinders the reduction of iron loss of the product. Therefore, N ≦ 0.01
It should be 0% or less.

Si is added to increase the specific resistance of the steel sheet and reduce the eddy current loss, as is well known in the art. If Si is added in excess of 4.0%, the workability will be extremely deteriorated and cold rolling will become difficult. But 1
Pickling and cold rolling became possible by applying a warm treatment at 00 ° C. to 300 ° C. and by reducing the thickness of the cast ingot. For this reason, simply having a high Si content is no longer a major problem in the production of high-silicon non-oriented electrical steel sheets. Further, as is well known in the art, since the Fe—Si alloy has an extremely small magnetostriction at 6.5% Si, it improves noise in electrical equipment. A
Similarly to Si, l is added to increase the specific resistance of the steel sheet and reduce the eddy current loss. For this purpose, a non-oriented electrical steel sheet that has not been conventionally transformed has a maximum Al content of 2.0%.
Has been added. Although it is possible in principle to increase the added amount, the maximum Si content is 2.0% in consideration of the manufacturing cost because the Si content is already large.

If the content of Mn is less than 0.1%, the workability of the product is deteriorated, and Mn is added to render S harmless. However, if the added amount of Mn exceeds 2.0%, the magnetic flux density of the product is significantly deteriorated, so Mn ≦ 2.0% must be satisfied. Also B
Is added as needed to render N harmless. That is, when it is added, it is necessary to balance with the amount of N, so the maximum content is made 0.005%. If ultra-low nitrogen steel is melted, N can be rendered harmless, and in this case, the need for addition is small.

Next, the manufacturing process conditions of the present invention will be described. When the cast steel strip obtained by solidifying by the moving and renewing cooling body surface is rolled at a relatively high cold rolling rate, the magnetic flux density is high, but the columnar crystals formed during the solidification process have this high rolling rate. The recrystallized texture of the product sheet is similar to that of the steel sheet normal ‖ <111> axial density and the steel sheet normal ‖ <100> axial density, which is an ideal texture for non-oriented electrical steel sheets. Absent. The inventors of the present invention have conducted extensive studies and found that at a cold rolling reduction of less than 40% (preferably less than 30%), the recrystallized texture after finish annealing was caused by the columnar crystals formed during casting as nuclei. , Almost perfect, {100} <0vw) (random cube)
I found that The reason for this is not clear yet, but the texture of columnar crystals is {100} <0vw>.
(Random cube) is relatively hard to accumulate processing strain, so at a low cold rolling reduction, the rolling texture remains the same as the random cube, and at the recrystallization stage during finish annealing,
It is considered that this is due to recrystallization and grain growth (rather, it should be called strain-induced grain boundary movement), and the random cube is sharpened. Further, if the cold rolling reduction is less than 5%, the surface properties at the time of casting remain as they are and are not suitable for the product. Further, also from the viewpoint of cold rolling property, such a light reduction of a high silicon material (5 to 40%, preferably 5 to 30%)
Is more suitable for actual production than the conventional cold rolling rate of around 70%. FIG. 1 shows that a molten steel containing Si: 6.3 to 6.7% (weight) is solidified by a moving and renewing surface of a cooling body to form a cast steel strip, and then the corresponding cast steel strip is cold-rolled to a predetermined temperature. In the method for producing a non-oriented electrical steel sheet, which is subjected to finish annealing after being made to have a thickness, the cold rolling rate and the magnetic flux density (B50
(T)) is shown. From this figure, it is understood that the rolling reduction is preferably 5 to 40% as described above. Further, it is conceivable that the product is cast at the product thickness. In this case, the surface properties are not suitable for the product as in the case of the cold rolling reduction of less than 5%, and as shown in FIG. Is not very good.

FIG. 2 shows the texture of the finished annealed product sheet obtained in the present invention. As you can see, a very nice so-called random cube is obtained. It can be said that this is ideal for high silicon non-oriented electrical steel sheets.

[0014]

The embodiments of the present invention will be described below. Directly 0.56 mm by solidifying the molten steel (comprising the balance Fe and unavoidable impurities) of the components shown in Table 1 on the surface of the moving cooling body
And a steel strip of 0.62 mm was obtained. After that, pickling,
Cold rolled to a thickness of 0.50 mm. The cold-rolled steel sheet was degreased and annealed at 1050 ° C. for 30 seconds in a continuous annealing furnace. Then, the magnetic characteristics (average every 22.5 degrees) were measured by the Epstein method. These values were compared with the case of the cold rolling ratio of 40% or more (steel thickness of 2.0 mm and 1.5 mm) which is a comparative method.

[0015]

[Table 1]

A high-silicon non-oriented electrical steel sheet that is solidified by the moving and renewing surface of the cooling body to form a cast steel strip, and then the corresponding cast steel strip is cold-rolled to a predetermined thickness and then finish-annealed. In the manufacturing method described above, when the rolling rate is set to 5% or more and less than 40% during cold rolling, a high-silicon non-oriented electrical steel sheet having extremely excellent magnetic properties as compared with the case where the cold rolling rate is high can be obtained.

[0017]

As described above, according to the present invention, the non-oriented electrical steel sheet containing high Si is solidified on the surface of the cooling body to be moved and renewed, and is obtained by rolling at a low proper cold rolling rate. It is possible to obtain a product having extremely excellent magnetic properties.

[Brief description of drawings]

FIG. 1 is a diagram showing a relationship between a cold rolling rate and a magnetic flux density.

FIG. 2 is a {100} positive electrode diagram of the finish annealed material of the present invention.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Reference number within the agency FI Technical display location C22C 38/06 (72) Inventor Hodaka Hodaka No. 1 Tobata-cho, Tobata-ku, Kitakyushu-shi, Fukuoka New Japan Steelworks Yawata Works

Claims (1)

[Claims] 1. In% by weight, 4.0% <Si ≦ 8.0%,
Molten steel consisting of Al ≦ 2.0%, balance Fe and unavoidable impurities is solidified into a cast steel strip by the moving and renewing surface of the cooling body, and then the cast steel strip is cold-rolled to a predetermined thickness. In the method for producing a high silicon-containing non-oriented electrical steel sheet, which is subsequently finish-annealed, a high silicon non-oriented electromagnetic sheet having extremely excellent magnetic properties, characterized in that a rolling ratio is set to 5% or more and less than 40% during cold rolling. Steel plate manufacturing method.