CN111375632A - Method for preparing gradient structure material by using cryogenic roller - Google Patents

Abstract

A method for preparing a gradient structure material by using a cryogenic roller comprises the steps of putting an alloy plate into a heating furnace, wherein the heating temperature is (0.7-0.9) Tm, and the Tm is the melting point of the alloy plate material; starting a cryogenic treatment device, and reducing the temperature of a working roll of a continuous rolling unit to-150 to-100 ℃; and taking out the alloy plate from the heating furnace, and sending the alloy plate into a continuous rolling unit for continuous rolling, wherein the reduction rate of each pass of the rolled piece after passing through a roller is 1-5%, and the total reduction rate of the rolled piece is 30-50%, so that the gradient structure plate is obtained. The alloy plate can be an aluminum alloy, a copper alloy or a medium/high entropy alloy plate. The invention can realize the preparation of gradient structure materials, especially large-size gradient structure strips, the surface layer of the obtained material is ultrafine grains, the core part of the obtained material is coarse grains, and the material has the mechanical properties of the ultrafine grain material and the coarse grain material.

Description

A method for preparing gradient structure materials using cryogenic rolls

technical field

The invention belongs to the technical field of metal material rolling, and particularly relates to a method for preparing a gradient structure material by using a cryogenic roll.

Background technique

With the rapid development of various fields such as aviation industry, automobile industry and electronic communication industry, the demand for lightweight and miniaturization of materials is gradually increasing. The preparation of high-performance materials is one of the hotspots of research at home and abroad. Large plastic deformation has strong grain refining ability, and can directly refine the internal structure of materials to sub-micron or even nano-scale, which is an effective preparation method for the preparation of bulk nano/ultrafine-grained materials. It can be seen from the Hall-Petch formula that grain refinement can continuously enhance the strength of the material. However, for nano/ultrafine grained materials, the strength and toughness are often in an "inverted" relationship, and the reduction of material toughness greatly limits the material's performance. practical application.

Gradient structure means that the structural unit size (such as grain size or lamella thickness) of a material varies spatially with a gradient, increasing continuously from the nanoscale to the macroscale. Due to the gradient distribution of the material structural units, the properties of the material also exhibit the characteristics of gradient distribution. Therefore, the gradient structure material can make the material exhibit high strength of nano/ultrafine grains and good toughness of coarse grains at the same time, which overcomes the traditional nano/ultrafine grains. The "inverted" relationship between strength and toughness in fine-grained materials provides a new idea for the study of strength-toughness matching of materials. In promoting the industrial application of gradient structure materials, it is necessary to realize large-scale continuous preparation of gradient structure materials. In the existing preparation methods, the shape and size of the materials to be processed are limited due to the influence of processing methods. How to realize the industrial production of gradient structure materials is the key issue that determines its application prospects.

SUMMARY OF THE INVENTION

In order to overcome the above-mentioned shortcomings of the prior art, the purpose of the present invention is to provide a method for preparing a gradient structure material by using a cryogenic roll, and the gradient structure material prepared by this method effectively combines the advantages of coarse-grained materials and ultra-fine-grained materials. , has good comprehensive mechanical properties and can be used in the preparation of industrial products such as automobiles.

In order to achieve the above object, the technical scheme adopted in the present invention is:

A method for preparing a gradient structure material by using a cryogenic roll, comprising:

The first step: put the alloy plate into the heating furnace, the heating temperature is (0.7 ~ 0.9) Tm, and Tm is the melting point of the alloy plate material;

The second step: turn on the cryogenic treatment device, and reduce the temperature of the work rolls of the continuous rolling mill to -150～-100℃;

The third step: take out the alloy plate from the heating furnace and send it to the continuous rolling unit for continuous rolling. A gradient structure plate is obtained.

The alloy plate can be aluminum alloy, copper alloy or medium/high entropy alloy plate.

The thickness of the alloy plate is generally 1-10mm.

After heating in the first step, the temperature can be kept for 0.5 to 4 hours according to the thickness of the alloy plate.

In the third step, the alloy sheet is passed through the cryogenic rolling mill as fast as possible, and the rolling speed is 0.5-5 m/s.

Compared with the prior art, the present invention can realize the preparation of gradient structure materials, especially large-size gradient structure strips, the surface layer of the obtained material is ultra-fine grains and the core is coarse grains, and both ultra-fine grain materials and coarse grains are combined. The mechanical properties of the material, the invention is suitable for aluminum alloy, copper alloy, medium/high entropy alloy and other materials, and has industrial application prospects in the fields of gradient structure material preparation and automobile industry.

Description of drawings

Figure 1 is a schematic diagram of the process flow of the present invention, the dotted frame on the left in the figure is the heating link, and the dotted frame on the right is the gradient material cryogenic rolling link.

Fig. 2 is a schematic diagram of a gradient structure material prepared by the present invention, the surface layer is of ultra-fine grain/nano-crystal structure, and the core region is of coarse-grain structure.

Detailed ways

The embodiments of the present invention will be described in detail below with reference to the accompanying drawings and examples.

The present invention is a method for preparing gradient structure materials by using cryogenic rolls. Through the cryogenically treated rolls, the surface area of the rolled piece can be subjected to large plastic deformation, and at the same time, the surface temperature of the material is rapidly cooled to the cryogenic temperature, and finally the core of the rolled piece is coarse-grained and the surface layer becomes ultra-fine grained or even nanocrystalline , the gradient structure materials were prepared. Through this process, the comprehensive mechanical properties of the metal strip are improved.

The specific process of the present invention is shown in Figure 1, including:

The first step: take the alloy strip 2 as the raw material, the raw material can be aluminum alloy strip, copper alloy strip, medium/high entropy alloy strip, etc., the thickness is 1-10mm.

The second step: put the alloy strip 2 into the heating furnace 1, the heating temperature is 0.7-0.9Tm (Tm is the melting point of the alloy), and the holding time is 0.5-4 hours according to the thickness of the material.

The third step: turn on the cryogenic treatment device 4, and reduce the temperature of the work rolls of the continuous rolling group 5 to -150～-100°C.

The fourth step: turn on the continuous rolling unit 5, take out the heated alloy strip 3 and pass through the cryogenic continuous rolling unit 5 as quickly as possible, and the rolling speed is 0.5-5 m/s. After the rolling stock passes through the roll, the reduction rate of each pass is 1-5%, the total reduction rate of the rolling stock is 30-50%, and a high-performance gradient structure material is prepared.

The gradient structure material prepared by this method is shown in Figure 2. The elongation of this material is similar to that of hot-rolled strip, but the strength of the material exceeds that of hot-rolled strip by more than 50%.

In a specific embodiment 1 of the present invention, the alloy strip 2 is a T2 copper alloy strip with a thickness of 8 mm, the heating temperature is 800 ° C, the holding time is 2 hours, the temperature of the work roll is reduced to -150 ° C, and the rolled piece passes through The reduction ratio of each pass after rolling is 2%, and the total reduction ratio is 35%, and finally a high-performance gradient structure T2 copper strip is obtained. The copper strip with gradient structure has an elongation of over 40% and a strength of over 400 MPa.

In a specific embodiment 2 of the present invention, the alloy strip 2 is a 6061 aluminum alloy strip with a thickness of 6 mm, the heating temperature is 450° C., the holding time is 1 hour, the temperature of the work roll is reduced to -120° C. The reduction ratio of each pass after rolling is 5%, and the total reduction ratio is 40%, and finally a high-performance gradient structure 6061 aluminum alloy material is obtained. The elongation of 6061 aluminum alloy strip with gradient structure is over 30%, and the strength is over 300MPa.

Claims (5)

1. A method for preparing a gradient structure material by using a cryogenic roller is characterized by comprising the following steps:

the first step is as follows: putting the alloy plate into a heating furnace, wherein the heating temperature is (0.7-0.9) Tm, and the Tm is the melting point of the alloy plate material;

the second step is that: starting a cryogenic treatment device, and reducing the temperature of a working roll of a continuous rolling unit to-150 to-100 ℃;

the third step: and taking out the alloy plate from the heating furnace, and sending the alloy plate into a continuous rolling unit for continuous rolling, wherein the reduction rate of each pass of the rolled piece after passing through a roller is 1-5%, and the total reduction rate of the rolled piece is 30-50%, so that the gradient structure plate is obtained.

2. The method for preparing the gradient structure material by the cryogenic roller according to claim 1, wherein the alloy plate is an aluminum alloy, a copper alloy or a medium/high entropy alloy plate.

3. The method for preparing the gradient structure material by using the cryogenic roller according to the claim 1 or 2, wherein the thickness of the alloy plate is 1-10 mm.

4. The method for preparing the gradient structure material by using the cryogenic roller as claimed in claim 1, wherein the temperature is maintained for 0.5 to 4 hours according to the thickness of the alloy plate after the heating in the first step.

5. The method for preparing the gradient structure material by the cryogenic roller according to claim 1, wherein in the third step, the alloy plate is passed through the deep cold rolling mill unit as fast as possible, and the rolling speed is 0.5-5 m/s.

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