JPS5831366B2 - Manufacturing method of non-oriented silicon steel sheet - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing non-oriented silicon steel, and particularly the present invention relates to a method for producing a non-oriented silicon steel plate having low core loss, high magnetic permeability, and high magnetic flux density. .

Among non-oriented silicon steels, those with high Si and At contents undergo ridging during the manufacturing process.

As one method of preventing this ridging, a method of annealing a hot coil is known.

On the other hand, it is known that annealing a hot coil, which is the raw material for a fully processed or semi-processed non-oriented silicon steel sheet, reduces core loss and improves magnetic permeability and magnetic flux density.

Annealing a non-oriented silicon steel hot coil in this way is an effective means for preventing bulging and improving electromagnetic properties.

For the above-mentioned annealing, a continuous annealing method and a bell annealing method are used.

According to Bell annealing, compared to continuous annealing, heating,
Since the cooling rate can be slowed down, it is believed that the agglomeration of precipitates such as nitrides and sulfides is promoted, which promotes crystal grain growth and improves the electromagnetic properties of the product.

Furthermore, since a sufficiently long soaking time can be used, the hot coil recrystallized grains can grow sufficiently, leading to improved electromagnetic properties.

However, it is known that when a non-oriented silicon steel sheet containing Si and A7 is subjected to bell annealing, nitridation occurs and the electromagnetic properties deteriorate, and furthermore, the problem of oxidation of the surface of the steel sheet occurs. ing.

HN is used as an annealing gas to prevent oxidation on the surface of the above steel plate.
Alternatively, even when using a non-oxidizing gas such as N2, At203. A disadvantage is that reduced scale composed of SiO2, FeO, etc. is generated, and this scale cannot be completely removed even if shot blasting or pickling is performed alone or in combination after annealing, and in some cases, the product surface may deteriorate. was there.

The purpose of the present invention is to provide a method for manufacturing a non-oriented silicon steel sheet that eliminates and improves the above-mentioned drawbacks of conventional methods,
The above object can be achieved by the method described in the claims.

Next, the present invention will be explained in detail.

In order to solve various problems that occur when bell annealing non-oriented silicon steel sheets, the present invention prevents nitridation by adding sb or Sn to the steel, and
This is intended to prevent oxidation and the generation of reduced scale by completely blocking contact between oxygen and metal during hot coil annealing.

According to the present invention, as a first means, black scale is removed by shot blasting or pickling before hot coil annealing.

As a result, the 02 min contained in the black scale is substantially removed from the hot coil surface.

Next, as a second method, first, before raising the temperature, the gas inside the bell is completely replaced with a gas such as N2 y Ar, and then the bell is heated, soaked, cooled, and then dismantled.
A403. This is carried out after the temperature is lower than that at which an internal oxidation layer made of FeO or the like is not formed.

In addition, the annealing gas used during the soaking and cooling is the Si in the steel plate.
and N2 with the 02 content as low as possible so as not to oxidize At. It is advantageous to use non-oxidizing gases such as HN, Ar, etc.

* * By using the above two means, the object of the present invention can be distantly achieved without generating scale during annealing of a hot coil for a non-oriented silicon steel plate.

Further, according to the present invention, it is also possible to omit pickling or shot blasting after annealing.

Next, the present invention will be explained with reference to examples.

Example I Si 2.71%, Mn 0.34%, A,! 0.41
%.

A non-oriented silicon steel material consisting of Sb0.048, rare earth element 0.018, unavoidable impurities, and Fe is melted through an LD converter and subsequent vacuum degassing treatment, and a 200 mm thick slab is made by continuous casting. Manufactured.

After that, this slab is subjected to normal hot rolling for 2 to 3
I made 4 turns of mm hot coil.

For these coils, the levels A, B, C, and Table 1 below are applied.
Hot coil treatment was performed under the conditions shown in D.

Each coil thus obtained was subjected to shot blasting and pickling treatment, and then cold rolled to a diameter of 0.50.
mm cold coil and continuous annealing furnace at 920℃
1.Tai-Kong annealing was applied.

Table 2 shows the surface properties and electromagnetic properties of the product thus obtained.

As described above, according to the present invention, it was possible to produce an electrical steel sheet with a good surface, low iron loss, and high magnetic flux density.

Example 2 Si 1.50%, Mn 0.31%, Ato, 34%.

A semi-processed non-oriented silicon steel material consisting of 0.069% Sb and the balance unavoidable impurities and Fe is melted in a bottom blowing converter, made into a steel ingot by the bottom pouring ingot method, and then made into a 2601m thick slab by blooming rolling. And so.

Thereafter, normal hot rolling was carried out to produce 5 turns of a 2.3-speed hot coil.

These coils are measured at levels A, B, C, and Table 3 below, respectively.
Hot coil treatment was performed under the conditions shown in I) and E.

Each coil was cold rolled after HCt pickling, and 0.
It was made into a cold coil of 50 mm and annealed at 750°C x 1 coil in a continuous annealing furnace.

The electromagnetic properties of the surface of the obtained product and after strain relief annealing at 800° C.XIHr in N2 are shown in Table 4 below.

As described above, according to the present invention, it is possible to manufacture a semi-processed non-oriented silicon steel sheet having a good product surface and low core loss and high magnetic permeability.

Claims (1)

[Claims] A non-oriented silicon steel material containing Si, At, and at least one of Sb and Sn to prevent nitriding during annealing is hot-rolled, and the hot-rolled sheet coil thus obtained is In a method for manufacturing a non-oriented silicon steel sheet comprising a series of steps of bell annealing, cold rolling to obtain a final gauge cold rolled sheet, and then final annealing, the hot rolling after the hot rolling A method for producing a non-oriented silicon steel sheet, which comprises removing an oxide layer existing on the surface of a sheet coil, and then subjecting it to bell annealing in an atmosphere that does not oxidize Si and At.