JPH11293450A - Production of silicon steel sheet having silicon concentration distribution using siliconizing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a prescribed Si concn. distribution, to suppress the generation of pushing flaws on a steel sheet surface in a furnace and to improve a surface shape by penetrating Si into the steel sheet from its surface by using a vertical type furnace, then executing a diffusing treatment and stopping the diffusing treatment while there is an Si concn. gradient in the thickness direction of the steel sheet. SOLUTION: The steel sheet S is continuously treated by using the vertical type furnace arranged with a heating furnace 1, a siliconizing treatment furnace 2, a diffusing treatment furnace 3 and a cooling furnace 4 successively from below in a perpendicular direction. The steel sheet S is heated at about 1200 deg.C in the heating furnace 1 and thereafter, gaseous SiCl4 is introduced into the siliconizing treatment furnace 2 and the Si is penetrated into the steel sheet S surface in a non-oxidizing gaseous atmosphere contg. the gaseous SiCl4 . The steel sheet is then subjected to the diffusing treatment in the non-oxidizing gaseous atmosphere in the diffusing treatment furnace 3. While the Si concn. gradient exists in this diffusing treatment, the diffusing treatment is stopped and the diffusing rate is so controlled that the desired Si concn. distribution is formed. The in-furnace residence time of the steel sheet is, therefore, shortened and the probability of the deformation by high-temp. creep and the breakage in the furnace may be lowered.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention
The present invention relates to a method for manufacturing a silicon steel sheet having an i concentration distribution.

[0002]

2. Description of the Related Art High silicon steel sheets are used for core materials of transformers and motors. As the Si content increases, the iron loss decreases. %, It is known that the magnetostriction becomes 0 and the magnetic permeability becomes excellent, such as the peak of the maximum magnetic permeability.

Conventionally, as a method for manufacturing a high silicon steel sheet, a so-called siliconizing method has been known in which low silicon steel is made into a thin sheet by rolling, and then Si is diffused from the surface of the steel sheet. However, it takes an extremely long time to produce a high silicon steel sheet having a uniform Si concentration by diffusion. Further, conventionally, when manufacturing a high silicon steel sheet by such a siliconizing method, at a high temperature for a long time,
Since the steel sheet is retained, there is a problem of deformation due to creep and rupture in the furnace, and a low-tensile threading technique in a horizontal furnace has been required.

Therefore, Japanese Patent Application Laid-Open Nos. 62-22703 and 62-227036, and Japanese Patent Publication No. 5-497
No. 44 discloses that the Si concentration in the surface layer is 6.5 wt. %, It is proposed that the diffusion process be stopped when the Si concentration distribution exists in the plate thickness direction to shorten the overall processing time. Further, it is shown that the silicon steel sheet on which the Si distribution is formed in this manner has a low iron loss.

On the other hand, Japanese Patent Application Laid-Open No. 9-184051 discloses that it is effective to form a Si concentration gradient in the thickness direction in order to reduce the residual magnetic flux density, which is a cause of magnetic declination. .

[0006] However, in the conventional siliconizing method disclosed in the above-mentioned publication, since the continuous processing is performed using a horizontal furnace, the furnace length becomes several tens of meters, and rolls for supporting the steel sheet at regular intervals are provided. Need to be installed. This transport roll has a problem that a press flaw is generated on the surface of the steel sheet due to the adhesion of refractory material in the furnace or the product (SiO2) in the furnace.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and it is possible to suppress the occurrence of a press flaw on the surface of a steel sheet in a furnace and to obtain a sheet having a good surface property. An object of the present invention is to provide a method for manufacturing a silicon steel sheet having a Si concentration distribution using a siliconizing method, which can manufacture a silicon steel sheet having a Si concentration gradient in a direction.

[0008]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention uses a vertical furnace, and a siliconizing treatment for infiltrating Si from the surface of a steel sheet and a diffusion treatment for diffusing Si into the steel sheet. And diffusion treatment is performed in the thickness direction of the steel sheet.
A method for producing a silicon steel sheet having a Si concentration distribution using a silicon silicification method, wherein the silicon steel sheet is cut off while a concentration gradient is present to form a predetermined Si concentration distribution.

In this case, the steel sheet is subjected to a siliconizing treatment in a non-oxidizing gas atmosphere containing a Si-based compound, and then is subjected to a Si diffusion treatment in a non-oxidizing gas atmosphere containing no Si-based compound to thereby diffuse the Si. , A predetermined Si concentration distribution can be formed.

In addition, the siliconizing treatment for infiltrating Si from the surface of the steel sheet and the diffusion treatment for diffusing permeated Si into the steel sheet are simultaneously performed in a non-oxidizing atmosphere containing a Si compound to control the siliconizing and diffusion rate. By doing so, a predetermined Si concentration distribution can be formed.

According to the present invention, since the siliconizing treatment and the diffusion treatment are performed using a vertical furnace, the number of hearth rolls to be installed in the furnace can be reduced as compared with the horizontal furnace. It is possible to suppress the occurrence of press flaws on the surface, and it is possible to manufacture a silicon steel sheet having good surface properties.

Further, the Si concentration in the surface layer is set to
The diffusion process is terminated while the concentration is higher than the predetermined
Since the concentration distribution is formed, the time in the furnace of the steel sheet can be shortened, and the possibility of deformation due to high-temperature creep and fracture in the furnace can be reduced. Further, since the surface Si concentration has a higher Si concentration gradient than the Si concentration at the center of the plate thickness, it is possible to obtain a silicon steel sheet having good workability, high-frequency iron loss and low residual magnetic flux density.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be specifically described below. In the present invention, in manufacturing a silicon steel sheet having a Si concentration distribution using a siliconizing method, using a vertical furnace,
Perform siliconizing treatment to infiltrate Si from the surface of the steel sheet and diffusion treatment to diffuse the infiltrated Si into the steel sheet, and discontinue the diffusion processing while there is a concentration gradient of Si in the thickness direction of the steel sheet. To form

Here, the steel sheet is subjected to a siliconizing treatment in a non-oxidizing gas atmosphere containing a Si-based compound, and then a diffusion treatment of Si is carried out in a non-oxidizing gas atmosphere containing no Si-based compound.
The above-described Si concentration distribution can be formed by controlling the diffusion speed of i and cutting off while the Si concentration in the surface layer is higher than the Si concentration in the center of the plate thickness.

Further, the siliconizing treatment for infiltrating Si from the surface of the steel sheet and the diffusion treatment for diffusing the infiltrated Si into the steel sheet are simultaneously performed in a non-oxidizing atmosphere containing a Si compound to control the siliconizing and diffusion rate. Then, while the Si concentration in the surface layer is higher than the Si concentration in the center of the plate thickness, the cutting is performed.
The above-described Si concentration distribution can also be formed.

According to the latter method, the structure of the furnace can be simplified by simultaneously performing the siliconizing treatment and the diffusion treatment in the same atmosphere. It is also possible to easily control the Si concentration distribution by adjusting the atmosphere in the siliconizing / diffusion treatment furnace, adjusting the introduction position and flow rate of the Si compound gas, and the moving speed of the steel sheet S.
An extremely flexible process can be performed.

The siliconizing treatment is performed by a chemical vapor deposition (CVD) method using a Si-containing gas. The Si-containing gas used for the treatment is not particularly limited,
SiH ₄ , Si ₂ H ₅ , SiCl _{4 and the} like can be used, and among them, SiCl ₄ is preferable. Si as processing gas
When Cl ₄ is used, the treatment temperature is set to 1023 to 125
It is preferable that the temperature be in the range of 0 ° C. The concentration of SiCl ₄ during the siliconizing treatment and the diffusion treatment is 0.02 to 35 m.
ol% is preferable.

The processing of the present invention can be performed, for example, by the apparatus shown in FIG. This apparatus is a vertical furnace in which a heating furnace 1, a siliconizing furnace 2, a diffusion furnace 3, and a cooling furnace 4 are vertically arranged in order from the bottom, and the steel sheet S is continuously processed. You. That is, a predetermined temperature, for example, 12
After being heated at 00 ° C., the SiCl 2
_Four gases are introduced, Si is infiltrated into the surface layer of the steel sheet in a non-oxidizing gas atmosphere containing SiCl ₄ gas, and then diffusion processing is performed in a diffusion processing furnace 3 in a non-oxidizing gas atmosphere containing no SiCl ₄ gas. In this diffusion process, the diffusion process is stopped while the Si concentration gradient exists, and the diffusion speed is controlled so that a desired Si concentration distribution is formed. Then, it cools in the cooling furnace 4, and winds up. The process at this time is performed, for example, according to the temperature pattern shown in FIG.

The processing of the present invention can also be performed by the apparatus shown in FIG. This apparatus includes a heating furnace 11
Is a vertical furnace in which the siliconizing / diffusion processing furnace 12 and the cooling furnace 13 are vertically arranged in order from the bottom, and the steel sheet S is continuously processed. That is, after being heated at a predetermined temperature, for example, 1200 ° C. in the heating furnace 11, SiCl ₄ gas is introduced in the siliconizing / diffusion processing furnace 12, and the siliconizing processing and the diffusion processing are performed in a non-oxidizing gas atmosphere containing the SiCl ₄ gas. I do. The siliconizing / diffusion processing furnace 12 has a first zone 12a from the heating furnace side,
Second zone 12b, third zone 12c, fourth zone 12
d, a fifth zone 12e, each zone having SiC
l ₄ gas introducing nozzle is provided. Therefore, by controlling the flow rate of SiCl ₄ gas for each zone,
The processing time and processing interval of the siliconizing treatment and the diffusion treatment can be controlled. For example, adding silicon several times (siliconization)
And the diffusion can be performed continuously. Thus, by controlling the flow rate of the SiCl ₄ gas in each zone, and further adjusting the moving speed of the steel sheet S as necessary, it is possible to control the rate of siliconizing and diffusion of the steel sheet S,
The Si concentration distribution in the thickness direction of the steel sheet can be arbitrarily controlled. Thereafter, the steel sheet S whose Si concentration distribution is controlled in this way is cooled in the cooling furnace 13 and wound up. The process at this time is performed, for example, according to the temperature pattern shown in FIG.

Further, the processing of the present invention can also be performed by the apparatus shown in FIG. This apparatus includes a heating furnace 21
, A siliconizing furnace 22, a diffusion furnace 23, and a cooling furnace 24.
After the steel sheet S enters the heating furnace 21, moves vertically upward, enters the diffusion processing furnace 23 via the siliconizing furnace 22, moves vertically downward, and moves in the cooling furnace 24. This is a vertical furnace configured to be turned in the horizontal direction and wound up. In this apparatus, after heating at a predetermined temperature, for example, 1200 ° C. in a heating furnace 21, SiCl ₄ gas is introduced in a siliconizing furnace 22, and Si is applied to the surface layer of the steel sheet in a non-oxidizing gas atmosphere containing SiCl ₄ gas. Then, diffusion treatment is performed in a diffusion treatment furnace 23 in a non-oxidizing gas atmosphere containing no SiCl ₄ gas. In this diffusion process, Si
The diffusion process is terminated while the concentration gradient exists, and the diffusion speed is controlled so that a desired Si concentration distribution is formed.
Then, it cools in the cooling furnace 24, and winds up. The process at this time is performed, for example, according to the temperature pattern shown in FIG.

As described above, by performing the siliconizing treatment and the diffusion treatment in the vertical furnace, the number of hearth rolls installed in the furnace can be reduced as compared with the case of the horizontal furnace, and may be eliminated in some cases. Therefore, it is possible to suppress the occurrence of press flaws on the steel sheet surface in the furnace, and it is possible to manufacture a silicon steel sheet having good surface properties. Further, since a Si concentration gradient in which the surface Si concentration is higher than the Si concentration at the center of the plate thickness is formed, a silicon steel sheet having good workability, high-frequency iron loss and low residual magnetic flux density can be obtained.

[0022]

Embodiments of the present invention will be described below. (Embodiment 1) CVD is carried out by an apparatus as shown in FIG.
3.0 watts by a continuous siliconizing process using the
t. % Si, a steel sheet with a thickness of 0.2 mm
The l ₄ using the raw material gas, to produce a material having a Si concentration gradient in the thickness direction. In the production, the steel sheet was continuously supplied, and the heating, the siliconizing, the diffusion and the cooling were performed in this order. The furnace temperature was determined according to the furnace temperature pattern shown in FIG. For comparison, a material prepared by continuous siliconizing equipment in a horizontal furnace and having sufficiently diffused Si in the thickness direction was prepared.

Table 1 shows these manufacturing conditions, the values of the surface silicon concentration and the central silicon concentration, the magnetic properties, and the values based on the results of analyzing the silicon concentration distribution in the thickness direction of the steel sheet using an electron beam probe microanalyzer (EPMA). Shows workability and surface properties.

[0024]

[Table 1]

As shown in Table 1, the conditions 1 and 2, which are examples of the present invention, are treated in a vertical furnace, so that the silicon steel sheet having the Si concentration gradient has the excellent characteristics of low iron loss and low residue. Good surface properties could be obtained while maintaining the magnetic flux density and good workability.

(Example 2) With a device as shown in FIG. 3 described above, 2.5 wt. % Si, 3.0 wt. A material having a Si concentration gradient in the thickness direction was manufactured using a steel sheet having a thickness of 0.2 mm at two levels of% Si as a base material and SiCl ₄ as a raw material gas.

The inside of the siliconizing / diffusion processing furnace 12 was divided into five zones as described above, and a gas supply nozzle was arranged in each zone. By controlling the flow rate of the SiCl ₄ gas in each zone, several times of silicon addition / diffusion were continuously performed. The furnace temperature was determined according to the furnace temperature pattern shown in FIG. For comparison, a material manufactured by continuous siliconizing equipment in a horizontal furnace was also prepared.

Table 2 shows these production conditions, the values of the surface silicon concentration and the central silicon concentration, the magnetic properties, and the values based on the results of analyzing the silicon concentration distribution in the thickness direction of the steel sheet by using an electron probe microanalyzer (EPMA). Shows workability and surface properties.

[0029]

[Table 2]

As shown in Table 2, under the conditions 3 to 6 in which the treatment was performed according to the present invention, since the treatment was performed in the vertical furnace,
It was possible to obtain good surface properties while maintaining low iron loss, low residual magnetic flux density, and good workability, which are excellent properties of a silicon steel sheet having an i-concentration gradient. In particular, in this example, since the concentration gradient of Si could be finely controlled, a silicon steel sheet having low iron loss and low residual magnetic flux density and extremely good workability could be obtained.

(Example 3) With a device as shown in FIG. 5 described above, 3.0 wt. % Si, a steel sheet having a thickness of 0.2 mm was used as a base material, and SiCl ₄ was used as a raw material gas.
A material with a concentration gradient was produced. In the production, the steel sheet was continuously supplied, and the heating, the siliconizing, the diffusion and the cooling were performed in this order. The furnace temperature was determined according to the furnace temperature pattern shown in FIG. For comparison, a material prepared by continuous siliconizing equipment in a horizontal furnace and having sufficiently diffused Si in the thickness direction was prepared.

Table 3 shows these manufacturing conditions, the values of the surface silicon concentration and the central silicon concentration, the magnetic characteristics, and the values based on the results of analyzing the silicon concentration distribution in the thickness direction of the steel sheet by using an electron probe microanalyzer (EPMA). Shows workability and surface properties.

[0033]

[Table 3]

As shown in Table 3, the conditions 7 and 8 of the present invention are treated in a vertical furnace, so that the silicon steel sheet having the Si concentration gradient has the excellent characteristics of low iron loss and low residue. Good surface properties could be obtained while maintaining the magnetic flux density and good workability.

[0035]

As described above, according to the present invention,
Since a silicon steel sheet having a Si concentration gradient in the sheet thickness direction is manufactured using a vertical furnace, it is possible to suppress the occurrence of press flaws on the steel sheet surface in the furnace, and to manufacture a silicon steel sheet having good surface properties. Becomes possible. In addition, the diffusion process is terminated while the Si concentration in the surface layer is higher than the Si concentration in the center of the sheet thickness, and a predetermined Si concentration distribution is formed. In addition, the possibility of in-furnace rupture can be reduced. Furthermore, the surface Si
Since the concentration has a Si concentration gradient higher than the Si concentration at the center of the plate thickness, it is possible to obtain a silicon steel sheet having good workability, high-frequency iron loss and low residual magnetic flux density.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing an example of an apparatus for performing a method of the present invention.

FIG. 2 is a diagram showing an example of a temperature distribution in the apparatus of FIG.

FIG. 3 is a schematic configuration diagram showing another example of an apparatus for performing the method of the present invention.

FIG. 4 is a diagram showing an example of a temperature distribution in the device of FIG.

FIG. 5 is a schematic configuration diagram showing still another example of an apparatus for performing the method of the present invention.

FIG. 6 is a diagram showing an example of a temperature distribution in the device of FIG.

[Explanation of symbols]

 1,11,21; Heating furnace 2,22; Silicon treatment furnace 3,23; Diffusion treatment furnace 4,13,24; Cooling furnace 12; Silicon treatment / diffusion treatment furnace S;

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hironori Ninomiya 1-1-2 Marunouchi, Chiyoda-ku, Tokyo Inside Nihon Kokan Co., Ltd. (72) Inventor Tatsuhiko Hiratani 1-1-2 Marunouchi, Chiyoda-ku, Tokyo No.Nihon Kokan Co., Ltd.

Claims (3)

[Claims] 1. Using a vertical furnace, a siliconizing treatment for infiltrating Si from the steel sheet surface and a diffusion treatment for diffusing the infiltrated Si into the steel sheet are performed, and the diffusion treatment is performed in the thickness direction of the steel sheet.
A method for producing a silicon steel sheet having a Si concentration distribution using a silicon silicification method, wherein the silicon steel sheet is cut off while a concentration gradient is present to form a predetermined Si concentration distribution. 2. A steel sheet is subjected to a siliconizing treatment in a non-oxidizing gas atmosphere containing a Si-based compound, and then a Si diffusion treatment is carried out in a non-oxidizing gas atmosphere containing no Si-based compound to control the diffusion rate of Si. The method for producing a silicon steel sheet having a Si concentration distribution using the siliconizing method according to claim 1, wherein the method comprises: 3. A siliconizing treatment for infiltrating Si from the surface of the steel sheet and a diffusion treatment for diffusing the infiltrated Si into the steel sheet are simultaneously performed in a non-oxidizing atmosphere containing a Si compound to control the siliconizing and diffusion rate. 2. The method according to claim 1, wherein
A method for producing a silicon steel sheet having a Si concentration distribution using the siliconizing method described in 1 above.