JPS6179723A - Manufacture of high silicon steel strip having superior magnetic characteristic - Google Patents

Abstract

PURPOSE:To improve considerably the cold workability of a high Si steel strip and to enable the use of a brittle thick steel strip formed by a single roll method by carrying out hot rolling at a temp. at which recrystallization is not caused before cold rolling. CONSTITUTION:An iron alloy contg. 4-7wt% Si is melted, sprayed on the surface of a moving cooling body from a nozzle, and solidified by very rapid cooling to form a steel strip. This steel strip is hot rolled at 600-800 deg.C and >=30% draft. The hot rolled strip is pickled, cold rolled at >=20% draft, and annealed at >=800 deg.C to obtain a high Si steel strip.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to soft magnetic materials used in transformers, motors, etc.

(Prior Art) Fe-Si alloys are widely used as excellent soft magnetic materials.

In the F++-Si system, cold workability deteriorates significantly when the S1 steepness becomes 1 or more in soft magnetic properties. For this reason, conventionally, Si
The amount added was less than 4z. However, in recent years, a method called ultra-rapid solidification has been developed.

It became possible to manufacture S-band directly from molten metal.

If this method is followed, brittle Fe-Si containing 4i or more of Si will be produced.
Alloy thin plates can also be manufactured. Moreover, grain refinement by rapid cooling improves the cold workability of the obtained ribbon, making cold rolling possible, and many patents have been proposed.

(Problem to be solved by the invention) Fe-Si containing 4z or more of Si obtained by ultra-rapid solidification
Alloys do have improved workability, but there are limits to this as well.

For example, in the case of 8.5zSi steel, the reduction achieved by a series of cold rolling is less than 2 oz. In particular, when producing thick 11 strips, the cooling rate decreases and the possible cold rolling rate decreases.

Therefore, in order to perform rolling of 2 oz or more for texture control etc., heating and annealing must be repeated.

However, since the texture has a strong correlation with the cold rolling rate,
It is desirable that a reduction of 20% or more can be achieved through a series of pressure feedings.

The object of the present invention is to dramatically improve the cold workability of high 511M1 rapidly solidified ribbon.

(Means for solving the problem) In order to improve the cold workability of the ultra-rapidly solidified ribbon of high-grade 51 steel,
As a result of various studies, it has been found that cold workability can be significantly improved by hot rolling before cold rolling. However, it is important that the hot rolling temperature be within a range in which recrystallization does not occur, and in the case of steel containing 71 or less Si, it is necessary to set the temperature to 600 to 800°C.

In addition, in order to improve cold workability, the structure after hot rolling needs to be a so-called jata-like structure, and it has therefore been found that a reduction of 3 (H or more) is required for this purpose.

The present invention was made based on one or more findings. That is, the present invention has a rating of 4.0-7. Go
o 'Reduction in temperature range from 0 to 800 °C - IK30%
After performing the above hot rolling.

It is characterized by performing a combination of pickling, cold rolling at a rolling reduction of 20X or more, and annealing at an aoo''c or more.

The reasons for limiting the scope of the claims will be described below.

Amount of Si added: If Si is less than 4$, cold rolling is possible, so it is not covered by the present invention, and if Si exceeds 7z, the soft magnetic properties will deteriorate, so the upper limit should be set to 7. Gwt$.

Hot rolling temperature: Below 800"O, the recovery phenomenon does not occur and the effect of the present invention does not occur, which is the same as cold rolling. On the other hand,
1100" Recrystallization occurs when the temperature is 0 or more. I) Terror 00 to 8 (1 (1"C!).

Hot rolling rate: As mentioned above (for 30g or less, fibrous IM
R is I! The effect of the present invention does not occur.

Cold all rolling ratio: 2 (rolling of 3 g or less is excluded from the scope of the present invention because it can be rolled without using the method of the present invention.

Annealing temperature: Recrystallization does not occur below 800'O, so set it to 800'O or above.

(Function) According to the present invention described above, the cold workability of a copper strip can be significantly improved. This allows the texture to be controlled more freely as described above.

Another important effect is that it is possible to expand the manufacturable dimensions of steel strips made by ultra-rapid solidification.

In other words, conventionally, in order to ensure the cooling rate, the thickness of the m-band manufactured by the ultra-rapid solidification method is limited, and the maximum thickness is 10 mm.
It is 0μ or less. If the thickness is greater than this, the cooling rate decreases, causing coarsening of crystal grains, and as a result, the steel strip becomes extremely brittle.

On the other hand, the thickness of the silicon steel plate currently used for Daibi is 0.2 to 0.3 as in consideration of the assembly process. Therefore, the thickness of the steel strip using the #B rapid solidification method is also 0.2 to 0.
．． Although it is desirable to have three layers, it is difficult to increase the thickness for the reasons mentioned above, and for this reason, a difficult twin roll method is being studied. However, even with the twin roll method, the maximum plate thickness is limited to 150 l.

In contrast, according to the present invention, even if the steel strip becomes brittle due to increased plate thickness and reduced cooling rate, it is possible to cold-work the steel strip by performing the above-mentioned hot rolling. The scope of use can be greatly expanded.

(Example) Example I Melt the Fe-Si alloy shown in Table 1 and use a single roll method!
A steel strip with a thickness of 25 mm and a plate thickness of 50 tiles was obtained. 500 stiff steel strips
Hot rolling was carried out at a temperature of 5 oz to too'c,
After pickling, cold rolling was performed. In FIG. 6, which shows the relationship between the breaking reduction ratio during cold rolling and the hot rolling temperature, the hot rolling temperature at room temperature is a comparative material in which hot rolling does not occur.

From the same figure, it can be seen that those rolled at 800 to 800°C exhibit excellent cold workability.

Table 1 (Test Materials) Example ■ The steel strip produced in Example ■ was hot rolled at 700° C. while changing the rolling reduction ratio. After pickling, cold rolling was performed, and the relationship between the hot rolling rate and the rolling reduction at break during cold rolling is shown in FIG.

As shown in the figure, the material hot-rolled at 30% exhibits excellent cold workability.

Example 2 Fe-8,58XSi steel was melted and a W4 strip having a width of 20 m5 and a plate thickness of 530 mm was obtained by a single roll method. After hot rolling a part of this steel strip at 700℃ to 80%, it remains as cast*? ? Cold rolling was performed on the same schedule as F. The results are shown in Table 2.

Table 2 shows that the effects of the present invention are significantly exhibited when the plate thickness in the cast state is thick. In addition, when the plate thickness is thicker than 50 tiles, since the copper strip can be removed from the roll at a temperature of 800°C or higher, it is possible to hot-roll without reheating, and such rolling is also applicable to the present invention. included.

Example (2) The steel strip of Example M was subjected to four types of treatments shown in Table 3, and 1% magnetic strength was measured. The results are shown in Table 4. As shown in the table, Sample D exhibits crushed magnetic properties.

Table 4 (Effects of the Invention) As is clear from the examples above, according to the present invention, the cold workability of the m-band can be greatly improved, and the single roll roll, which was conventionally too brittle to be used, can be improved. This method has excellent effects such as the fact that thick steel strips produced by the method can be put to practical use.

[Brief explanation of drawings]

Fig. 1 is a graph showing the relationship between the fracture reduction ratio during cold rolling and the hot rolling temperature in an example of the present invention, and Fig. 2 is a graph showing the relationship between the rolling reduction ratio during cold rolling and the hot rolling temperature.
It is a graph showing the relationship between hot rolling rate and breaking reduction rate during cold rolling. Broken N folds - 1

Claims (1)

[Claims] A steel strip obtained by ultra-rapid solidification by melting an iron alloy containing 4.0 to 7.0 wt% Si and jetting it from a nozzle onto the surface of a moving cooling body is heated in a temperature range of 600 to 800 °C. A high-silicon steel strip with excellent magnetic properties characterized by hot rolling at a reduction rate of 30% or more, followed by pickling, cold rolling at a reduction rate of 20% or more, and annealing at 800°C or more. manufacturing method.