CN116116926A - Method for regulating and controlling overall flow tissue performance of thermal manufacturing of high-strength light aluminum alloy thick plate - Google Patents

Abstract

The invention discloses a method for regulating and controlling the overall flow tissue performance of thermal manufacturing of a high-strength light aluminum alloy thick plate, which comprises the following steps: carrying out large-deformation hot rolling cogging on an aluminum alloy ingot; heating an aluminum alloy thick plate; setting characteristic parameters of a constraint shear deformation die; starting a press machine, and applying pressure to the heated blank by a bending male die to enable the blank to be in full contact with a bending die to deform; flattening the blank; rotating the blank; applying pressure to the blank through the male die again to enable the blank to be completely attached to the die, and completing deformation; flattening the deformed plate through a flattening die pair; removing energy from the deformed plate material for heat treatment; after heating, the plate material continues to develop constraint shear deformation, and the accumulation of strain in the plate material is realized in such a cycle; carrying out solid solution treatment on the plate; and then carrying out aging treatment. The invention has the advantages of high grain refining efficiency, obvious grain refining effect, good microstructure stability of the material, green and pollution-free performance, wide application range and wide application prospect, and can prevent the growth of heat treatment grains after deformation.

Description

A whole-process microstructure and performance control method for hot manufacturing of high-strength and lightweight aluminum alloy thick plates

technical field

The invention belongs to the field of material processing, and in particular relates to a method for regulating the structure and performance of the whole process of thermal manufacturing of high-strength and light-weight aluminum alloy thick plates.

Background technique

With the rapid development of aviation, automobiles, military industry, ships and other fields, higher requirements are put forward for the comprehensive performance of aluminum alloys. According to the classic Hall-Petch relationship, fine-grain strengthening makes ultra-fine-grained materials have excellent mechanical properties different from traditional materials. There are two main methods for preparing ultra-fine-grained metal materials. The first type is called "bottom-up". Synthesis methods mainly include vapor phase condensation method, electrodeposition method and high-energy ball milling method, etc., which are easy to introduce impurities to cause pollution, and there are a large number of pores in the solidification and sintering process, which has obvious limitations. The second type of method is called the "top-down" refinement method, which mainly crushes and refines the original coarse grains inside the material through plastic deformation.

At present, the large plastic deformation methods for refining the material structure, such as the equal channel angular extrusion method and the high-pressure torsion method, are only suitable for laboratory research on small-sized samples, and cannot realize the preparation and production of large-sized ultra-fine-grained plates. industrial applications. Constrained shear deformation is a large plastic deformation method first proposed by Korean scholar Shin for the preparation of ultra-fine-grained sheets. By alternately bending and flattening the sheet, a large amount of plastic strain is accumulated inside the material to achieve grain refinement. , but the grain refinement ability and mechanical property improvement effect of this method are limited. The material prepared by the large plastic deformation process has high energy storage inside, and the microstructure shows high instability, and the original fine grains are easy to grow up in the subsequent heat treatment or deformation. After plastic deformation, aluminum alloy materials often need further heat treatment to control the type and quantity of the second phase. However, the current heat treatment method for aluminum alloys after large plastic deformation has obvious defects. Solution treatment leads to abnormal growth of grains. Seriously affect the material properties.

Contents of the invention

In view of the fact that the current research focuses on the grain refinement of the plate only through constrained shear deformation, there are low grain refinement efficiency, limited refinement effect, and small grains after deformation in the traditional large plastic deformation process of aluminum alloy. Problems such as large and coarsening are easy to occur in thermal deformation or subsequent heat treatment. The present invention proposes a method for controlling the structure and performance of the whole process of hot manufacturing of high-strength and light-weight aluminum alloy thick plates. The technical route includes large deformation of high-strength and light-weight aluminum alloy thick plates. Rolling-constrained shear deformation-heat preservation and energy removal-heat treatment process microstructure and performance control, with high grain refinement efficiency, obvious grain refinement effect, prevention of heat treatment grain growth after deformation, good material microstructure stability, Green and pollution-free and other advantages.

The invention proposes a combination method of large-deformation rolling and constrained shear deformation to accumulate sufficient plastic strain inside the material to prepare large-sized fine-grained thick plates. Rolling deformation can significantly improve defects such as coarse grains, segregation, and holes in the initial aluminum alloy ingot. During the rolling deformation process, the grain width decreases proportionally with the compression of the sample thickness, and the structure presents a slender and fibrous structure. The as-rolled aluminum alloy thick plate is heated to a certain temperature and subjected to constrained shear deformation. The plate will accumulate a large amount of plastic strain during the constrained shear process, and the plate as a whole is mainly in a state of shear stress. Compared with the aluminum alloy in the The continuous dynamic recrystallization that occurs in the traditional large plastic deformation process, the initial fiber slender grains are easy to undergo geometric dynamic recrystallization rapidly under the action of shear stress, and realize the efficient refinement of grains.

Materials prepared by large plastic deformation have high internal deformation energy storage and poor microstructure stability. The traditional process is to directly perform solution treatment on the material after large plastic deformation, resulting in the deformation energy storage inside the grains mainly driving the grain boundary migration for The grains grow and coarse grains appear. The present invention proposes a treatment method for eliminating or greatly reducing deformation energy storage, which can actively regulate the internal energy storage of materials after large plastic deformation in time, specifically keeping warm for a certain period of time in a suitable temperature range to reduce the consumption of deformation energy storage Mainly used for recrystallization and grain refinement.

The method for controlling the microstructure and performance of the whole process of thermal manufacturing of high-strength and light-weight aluminum alloy thick plates proposed by the present invention includes the following steps:

(1) Carry out large-deformation hot-rolling blanking of aluminum alloy ingots, the initial rolling temperature is 400-420°C, rolling 8-12 passes, the total deformation is 70%-90%;

(2) Aluminum alloy thick plate is heated, the heating temperature is 380-420 ℃, and the heat preservation is 15-25min;

(3) Set the characteristic parameters of the constrained shear deformation mold;

(4) Deformation: start the press, press the bending punch to apply pressure to the heated billet, so that the billet and the bending die are completely contacted and deformed;

(5) Blank flattening: flatten the deformed sheet through a flattening die;

(6) Rotating blank: through the ejector device of the press, the blank is ejected, and the blank is turned 180° horizontally;

(7) Deformation again: Apply pressure to the blank through the punch again to make it fully fit with the mold to complete the deformation;

(8) Blank flattening: the deformed sheet is flattened by the flattening die pair, and steps (4)-(8) are a deformation cycle;

(9) De-energy heat treatment of the deformed sheet metal at a temperature of 280-320°C for 60 minutes;

(10) Continue to carry out constrained shear deformation on the sheet after heating, and perform energy-removing heat treatment every time the deformation is completed, so as to achieve the accumulation of strain in the sheet in this cycle;

(11) Perform solid solution treatment on the sheet at a temperature of 450-500° C. for 80-100 minutes; then perform aging treatment at a temperature of 130-150° C. for 12 hours.

Preferably, the aluminum alloy is 7075 aluminum alloy.

Preferably, in step (3), the characteristic parameters of the constrained shear deformation mold are set as follows: the tooth width w is 20 mm, and the inclination angle θ is 45°.

Compared with the prior art, the beneficial effect of the present invention is that: compared with the traditional large plastic deformation method, the technical route proposed by the present invention has the following advantages: the combined deformation of rolling and constrained shear introduces a large amount of Shear plastic strain, the long fibrous grains in the rolling state are rapidly refined under the action of shear, the grain refinement efficiency is significantly improved, and the grain refinement effect is more obvious; the deformation storage of aluminum alloy thick plates with large plastic deformation is proposed The principle of active regulation enables the internal energy storage of the material to be used for recrystallization refinement instead of grain growth; through the joint regulation of aluminum alloy grain shape, strain accumulation mode and deformation structure energy, the grain size of large-sized thick plates is realized. High-efficiency refinement and performance improvement further expand the application range and usage scenarios of large plastic deformation.

Description of drawings

Figure 1 is a schematic diagram of the technical route of the microstructure and performance control method of the whole process of hot manufacturing of high-strength and lightweight aluminum alloy thick plates in the embodiment.

Fig. 2 is a principle diagram of constrained shear large plastic deformation in the embodiment.

Fig. 3 is a characteristic sectional view of the constrained shearing die in the embodiment.

Fig. 4 is the structure after rolling deformation in the embodiment.

Fig. 5 is an aluminum alloy thick plate in the embodiment.

Fig. 6 is the flattened aluminum alloy thick plate in the embodiment.

Fig. 7 is a KAM diagram of crystal grains before and after eliminating deformation energy storage in the embodiment.

Fig. 8 is the structure after 12 passes of constrained shear deformation in the embodiment.

Detailed ways

In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the following will clearly and completely describe the technical solutions of the embodiments of the present invention in conjunction with the drawings of the embodiments of the present invention. Apparently, the described embodiments are some, not all, embodiments of the present invention. Based on the described embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without creative effort fall within the protection scope of the present invention.

Example 1

According to Figures 1-3, this embodiment provides a method for controlling the microstructure and properties of a high-strength lightweight aluminum alloy thick plate with large deformation rolling-constrained shear deformation-heat preservation and energy removal-heat treatment. The steps are as follows:

(1) Taking 7075 aluminum alloy as an example, the ingot is subjected to large deformation hot rolling, the initial rolling temperature is 410 ℃, rolling 10 passes, the total deformation is 80%, the aluminum alloy thick plate after rolling deformation The organization is shown in Figure 4;

(2) Heating a 7075 aluminum alloy rolled plate with a thickness of 20mm at a heating temperature of 400°C and holding it for 20 minutes;

(3) The characteristic parameters of the restrained shearing mold selected in this example are: the tooth width w is 20mm, and the inclination angle θ is 45°;

(4) Deformation: Start the press, press the bending punch to apply pressure to the heated billet, so that the billet and the bending die are completely contacted and deformed, and the deformed aluminum alloy thick plate is shown in Figure 5;

(5) Blank flattening: the deformed sheet is flattened by a flattening die pair, and the flattened aluminum alloy thick plate is shown in Figure 6;

(6) Rotating blank: through the ejector device of the press, the blank is ejected, and the blank is turned 180° horizontally;

(7) Deformation again: Apply pressure to the blank through the punch again to make it fully fit with the mold to complete the deformation;

(8) Blank flattening: through the flattening die pair, the deformed sheet is flattened, so that the four deformations are one to this;

(9) De-energy heat treatment is performed on the deformed sheet at a temperature of 300°C for 60 minutes. The KAM diagram of the structure before and after de-energy is shown in Figure 7;

(10) Continue constrained shear deformation of the sheet after heating, and perform energy-removing heat treatment once after each deformation is completed. This cycle realizes the accumulation of strain in the sheet. The microstructure of the aluminum alloy thick plate after 12 passes of constrained shear deformation As shown in Figure 8;

(11) Carry out solid solution treatment to the plate at a temperature of 470°C for 90 minutes, followed by aging treatment at a temperature of 140°C for 12 hours;

(12) Finally, the grain size is refined from the initial 239.7 microns to 36.8 microns, and the tensile strength is increased from 538 MPa to 710 MPa.

The above description of the embodiments is for those of ordinary skill in the art to understand and use the present invention. It is obvious that those skilled in the art can easily make various modifications to these embodiments, and apply the general principles described here to other embodiments without creative efforts. Therefore, the present invention is not limited to the above-described embodiments. Improvements and modifications made by those skilled in the art according to the principles of the present invention without departing from the scope of the present invention shall fall within the protection scope of the present invention.

Claims (3)

1. A method for controlling the microstructure and performance of a high-strength light-weight aluminum alloy thick plate thermal manufacturing process, characterized in that it comprises the following steps: (1) Carry out large-deformation hot-rolling blanking of aluminum alloy ingots, the initial rolling temperature is 400-420°C, rolling 8-12 passes, the total deformation is 70%-90%; (2) Aluminum alloy thick plate is heated, the heating temperature is 380-420 ℃, and the heat preservation is 15-25min; (3) Set the characteristic parameters of the constrained shear deformation mold; (4) Deformation: start the press, press the bending punch to apply pressure to the heated billet, so that the billet and the bending die are completely contacted and deformed; (5) Blank flattening: flatten the deformed sheet through a flattening die; (6) Rotating blank: through the ejector device of the press, the blank is ejected, and the blank is turned 180° horizontally; (7) Deformation again: Apply pressure to the blank through the punch again to make it fully fit with the mold to complete the deformation; (8) Blank flattening: the deformed sheet is flattened by the flattening die pair, and steps (4)-(8) are a deformation cycle; (9) De-energy heat treatment of the deformed sheet metal at a temperature of 280-320°C for 60 minutes; (10) Continue to carry out constrained shear deformation on the sheet after heating, and perform energy-removing heat treatment every time the deformation is completed, so as to achieve the accumulation of strain in the sheet in this cycle; (11) Perform solid solution treatment on the sheet at a temperature of 450-500° C. for 80-100 minutes; then perform aging treatment at a temperature of 130-150° C. for 12 hours. 2. The method for controlling the microstructure and properties of the whole process of thermal manufacturing of high-strength and lightweight aluminum alloy thick plates according to claim 1, wherein the aluminum alloy is 7075 aluminum alloy. 3. The method for regulating the microstructure and performance of the whole process of hot manufacturing of high-strength and lightweight aluminum alloy thick plates according to claim 1, characterized in that in step (3), the characteristic parameters of the constrained shear deformation mold are set as follows: the tooth width w is 20mm, the inclination angle θ is 45°.

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