CN1528921A

CN1528921A - High-silica silicon-steel sheet heat treatment and multiple cold-rolling method

Info

Publication number: CN1528921A
Application number: CNA031254519A
Authority: CN
Inventors: 张联盟; 张涛; 沈强; 李然; 张东明; 员文杰; 王传彬
Original assignee: Wuhan University of Technology WUT
Current assignee: Wuhan University of Technology WUT
Priority date: 2003-09-25
Filing date: 2003-09-25
Publication date: 2004-09-15

Abstract

The invention provides a method for producing high brittleness silicon steel board by using two times of heat process and multiple tracks cold-roll adjustment compound technology in different temperature range to control the extending performance of belt material rolling. It carries on baking process to high silicon steel shin board green compact produced by powder pressing method in low temperature range, controls the content of silicon in irn particles in shin boards, the board material can maintain the malleability. It carries on multiple rolling cold process when the silicon steel board is brittled, thus controls the thickness smooth property, and compactability of board. Then carries on secondary baking processing in high temperature, thus there obtains th even silicon steel board. Finally, carries on stress adjustment and relief annealing process, thus the product can be obtained.

Description

Heat treatment and multiple cold rolling processing method for high silicon steel plate

Technical Field

The invention relates to a heat treatment process and a method for multiple cold rolling.

Background

The high silicon content ferrosilicon alloy (particularly, the silicon content is 6-7%) has excellent magnetic properties such as high magnetic permeability, low magnetostriction coefficient, low core loss at high frequency and the like, so that the ferrosilicon alloy can be widely applied to ferromagnetic conversion elements in various fields such as a current conversion system of an air conditioner and a refrigerator, a solar energy system, a tramcar energy system, an inverter, an XRD power supply system, an induction heating system, an ozone generator, a high-speed motor and generator, an automobile part, a direct current converter and the like. Due to its low core loss performance, it is possible to miniaturize the original equipment. The alloy low magnetostriction coefficient can reduce the noise of equipment in the use process, so the iron-silicon alloy with high silicon content is a soft magnetic material with excellent performance, which is beneficial to environmental protection and energy conservation.

The traditional production and manufacture of silicon steel plates adopt a method of casting an iron-silicon alloy ingot and then rolling the ingot into a belt. The method comprises the processes of melting the ferrosilicon steel ingot → cogging → hot rolling → annealing → acid washing → cold rolling → annealing → coating an insulating layer and the like, and has the disadvantages of complex process, large energy consumption and high material loss rate. Further, when the content of silicon in the Fe-Si alloy exceeds 4.5%, the workability is deteriorated, and rolling production cannot be performed. For the industrial production of silicon steel sheet containing more than 4.5% of silicon, only CVD siliconizing method of NKK company in Japan can be adopted at present. It uses silicon steel sheet containing 3% silicon as substrate, and utilizes CVD method to make SiCl pass through₄FeSi is generated on the surface of the steel plate through deposition reaction₃Then heating and diffusing to obtain the integral high-silicon steel plate. The main reaction is as follows: . Because the SiCl4 has great pollution to the environment, the CVD process greatly reduces the production efficiency of the material, and the process is relatively complex, the cost is high, the large-scale production is difficult, and the yield can not meet the actual market demand.

The powder rolling method is the most developing method for preparing silicon steel plates with high silicon content. The most critical step in the preparation technology is the heat treatment and rolling process of the powder rolling forming body. Through extensive literature and patent examination, no relevant report on the control of the rolling performance of the iron-silicon system by using the preparation technology in the invention is found.

Disclosure of Invention

The invention adopts a composite technology of two heat treatment processes in different temperature ranges and multiple cold rolling regulation and control to control the rolling performance of the strip.

The following details about the specific implementation process of the process flow (see fig. 1) of the present invention are as follows:

(1) and (3) carrying out intermediate sintering, namely primary sintering heat treatment, on the high-silicon-content silicon steel sheet green blank prepared by the powder rolling method in a lower temperature range. By controlling the sintering temperature, time and atmosphere, a certain amount of low-silicon-containing iron phase structures are kept in the matrix, so that the drawability of the plate is still kept after the plate has certain strength.

(2) And before the whole silicon steel plate is embrittled, performing cold rolling treatment on the strip subjected to intermediate sintering for multiple times. Thus, voids in the sintered body can be eliminated, and the overall compactness can be improved. And meanwhile, the thickness and the leveling performance of the plate can be controlled.

(3) And carrying out secondary sintering heat treatment in a high-temperature range to uniformly diffuse the iron and silicon elements so as to obtain the silicon steel plate with uniform components.

(4) And (3) adjusting the stress of the surface of the plate at a low reduction rate of 0.5-5% to control the flatness of the surface.

(5) And (3) performing stress relief annealing treatment at low temperature to obtain the brittle silicon steel plate with excellent magnetic property.

Because under 700 ℃, the iron-silicon does nothave obvious reaction diffusion phenomenon, and reaches the eutectic temperature of the iron-silicon when the temperature exceeds 1200 ℃. Therefore, the temperature of the primary sintering heat treatment is 950-1050 ℃, and the sintering time is 3-5 h. The high-temperature sintering heat treatment contributes to the magnetic performance of the sintered body very well, the temperature of the secondary sintering heat treatment is 1100-1300 ℃, and the sintering time is 3-10 h. And performing final stress relief annealing at 750-800 ℃ for 0.5-1 h. Using an active atmosphere H during the heat treatment₂Or inert atmosphere Ar, or H₂The mixed atmosphere with Ar was used as a gas flow atmosphere.

The invention provides a heat treatment process and multi-cold rolling regulation and control composite technology which can be applied to industrial scale production of silicon steel plates with high silicon content. Compared with the existing silicon steel plate preparation process, the method overcomes the limitation that the high-silicon steel plate can not be processed by rolling, has excellent performances of simple and easy operation and the like which are not possessed by the traditional silicon steel preparation process, and has great industrial application value.

Description of the drawings:

FIG. 1: heat treatment and rolling processing process flow chart of high silicon steel plate

FIG. 2: image of density of sample containing 6.0% silicon varying with process

FIG. 3: distribution diagram of Fe and Si elements of sample with 6.0% silicon after heat treatment

FIG. 4: figure of ring-shaped sample after 6.5% silicon steel sheet processing

Detailed description of the preferred embodiments

The following detailed description of specific embodiments of the invention refers to the accompanying drawings.

Example 1: taking a green iron-silicon rolling powder strip with silicon content of 6.0 percent, the thickness of 0.36mm and the sample size of 150 multiplied by 40mm, putting the green iron-silicon rolling powder strip into a tubular sintering furnace with flowing Ar atmosphere, carrying out primary sintering heat treatment, wherein the sintering temperature is 950 ℃, and the sintering time is 4 hours. The average silicon content in the crystal grains of the obtained sample is close to 3.0 percent, and the good millable performance is still kept due to the high silicon content on the surface of local particles.

The obtained product has smooth surface, thickness of 0.30mm and density of 7.4g/cm³The sample of (1).

And continuously placing the mixture into a tubular sintering furnace filled with flowing Ar atmosphere, and carrying out secondary sintering heat treatment, wherein the sintering temperature is 1100 ℃ and the sintering time is 3 h. The obtained sample had an average silicon content of approximately 6.0%. The surface element distribution is shown in fig. 2.

And the sample with smooth surface and uniform thickness can be obtained by fine rolling with the reduction rate of 3%. Finally, stress relief annealing is carried out for 1h at 800 ℃ in Ar atmosphere. The saturation magnetization of the obtained sample is 1.8T high-silicon iron silicon alloy strip.

The density variation curve in the whole process is shown in figure 3.

Example 2: taking a green iron-silicon rolling powder strip blank containing 6.5 percent ofsilicon, the thickness of the green iron-silicon rolling powder strip blank is 0.40mm, the size of a sample is 200 multiplied by 60mm, and placing the green iron-silicon rolling powder strip blank which is introduced with flowing Ar and H₂The primary sintering heat treatment is carried out in the mixed atmosphere, the sintering temperature is 1000 ℃, and the sintering time is 3 hours. The obtained sample had an average silicon content of approximately 3.5%.

And (3) carrying out cold rolling treatment at high reduction ratio for many times to obtain a sample with the thickness close to 0.25mm and high density.

And continuously putting the mixture into a tubular sintering furnace with flowing mixed atmosphere for secondary sintering heat treatment, wherein the sintering temperature is 1200 ℃, and the sintering time is 5 hours. The obtained sample had an average silicon content of approximately 6.3%. After fine rolling with the reduction rate of 1%, samples with smooth surfaces and uniform thickness can be obtained. Finally, stress relief annealing is carried out for 40min at 750 ℃ in a mixed atmosphere. The resulting sample had good processability and the image of the processed ring was as shown in FIG. 4.

Example 3: taking iron containing 7 percent of siliconA green silicon-calendered powder strip, having a thickness of 0.40mm and a sample size of 200X 40mm, is placed in a flow-through H₂Carrying out primary sintering heat treatment in the atmosphere, wherein the sintering temperature is 1050 ℃ and the sintering time is 5 h. The obtained sample had an average silicon content of approximately 4%.

The thickness of the alloy is close to 0.3mm after multiple times of cold rolling treatment with high reduction.

Continuously put into the furnace with H₂And carrying out secondary sintering heat treatment in an atmosphere tubular sintering furnace, wherein the sintering temperature is 1300 ℃, and the sintering time is 10 h. The obtained sample had an average silicon content of approximately 6.7%. After fine rolling with the reduction rate of 0.5%, a sample with smooth surface and uniform thickness can be obtained. Finally, stress relief annealing is carried out for 30min at 800 ℃ in mixed atmosphere. The final sample can be prepared.

Claims

1. A heat treatment and multiple cold rolling processing method for high silicon steel plates prepared by a powder rolling method is characterized in that the rolling performance of strips is controlled by utilizing a composite technology of two heat treatment processes in different temperature ranges and multiple cold rolling regulation, and the high silicon brittle silicon steel plates are prepared, and the specific method comprises the following steps: firstly, carrying out primary sintering heat treatment on a high-silicon-content silicon steel sheet green body, keeping the drawability performance by controlling the sintering temperature, time and atmosphere, then carrying out cold rolling treatment for multiple times to eliminate the cavity in the sintered body, then carrying out secondary sintering heat treatment in a high-temperature range to obtain a silicon steel sheet with uniform components, and finally, carrying out plate stress adjustment and stress relief annealing treatment at a low reduction rate of 0.5-5% to obtain a final brittle silicon steel sheet, wherein:

(1) the temperature range of the primary sintering heat treatment is 800-1000 ℃, and the sintering time is 3-5 h;

(2) the temperature range of the secondary sintering heat treatment is 1100-1300 ℃, and the sintering time is 3-10 h;

(3) the temperature range of the stress relief annealing process is 750-800 ℃, and the time is 0.5-1 h;

(4) using an active atmosphere H during the heat treatment₂Or inert atmosphere Ar, or H₂The mixed atmosphere with Ar was used as a gas flow atmosphere.