A method for obtaining multi-level heterogeneous strengthening structure of aluminum alloy

Abstract

The invention discloses a method for obtaining a multi-level heterogeneous strengthening structure of an aluminum alloy. The invention utilizes a solid solution-rapid heating large deformation-aging process method to obtain a uniform solid solution structure by solid solution treating an aluminum alloy billet; then a non-steady-state structure composed of unstable precipitation phases and dislocation substructures is obtained by rapid heating and large deformation; a multi-level heterogeneous strengthening structure in which precipitation phases of different sizes and coarse grains and fine grains coexist is formed by aging treatment; and a multi-level heterogeneous strengthening structure is prepared, thereby improving the mechanical properties of the aluminum alloy, such as the hardness and strength.

Description

Technical Field

[0001] The invention relates to the technical field of aluminum alloy thermal processing, and in particular to a method for obtaining a multi-level heterogeneous strengthening structure of an aluminum alloy. Background Art

[0002] High-strength aluminum alloy components are widely used in the fields of aerospace and weapons and equipment. Their lightweight and high-strength performance requirements are constantly increasing with the improvement of the service performance of components and equipment. Since the microstructure determines the macroscopic performance, it is crucial to prepare aluminum alloy multi-level heterogeneous strengthening structures with excellent performance through the combination of appropriate heat treatment and plastic forming to improve the performance of aluminum alloy components.

[0003] Normally, in order to improve the deformation capacity of aluminum alloys, aluminum alloy billets are usually annealed, then deformed, and then subjected to solution aging treatment, i.e., annealing-deformation-solid solution aging treatment. Although this process route can improve the mechanical properties of components to a certain extent, it is difficult to meet its ever-increasing performance requirements. In addition, solution aging after deformation is likely to cause quenching deformation of the sample.

[0004] The literature [https: / / doi.org / 10.3390 / ma14237383] introduces the method of solid solution-cold rolling-aging to improve the performance of cast 2219 aluminum alloy. However, in the actual large deformation process, due to the high hardness of the solid solution aluminum alloy, cracking is very likely to occur during deformation, especially at the edge of the sample. Studies have found that when the solid solution 2195 aluminum-lithium alloy is compressed by about 30% at room temperature, cracking defects will occur. Therefore, the patent of the present invention innovatively proposes a method of solution treatment-rapid heating and large deformation-aging treatment, in which solution treatment is used to homogenize the structure of the annealed aluminum alloy and remove the coarse second phase particles in the structure that are easy to cause the nucleation and growth of voids, thereby avoiding crack formation and improving the deformation capacity of the material; rapid heating and large deformation utilize transient temperature fields and deformation fields to introduce non-steady-state structures composed of unstable precipitation phases and dislocation substructures that are conducive to aging. In addition, warm forming reduces the deformation resistance of the material. Studies have found that the deformation of the solid solution 2195 aluminum-lithium alloy can reach 70% when compressed at 400°C; the final aging treatment forms a multi-level heterogeneous strengthening structure with precipitation phases of different sizes and coarse and fine grains, thereby improving the mechanical properties of the aluminum alloy. Summary of the invention

[0005] The purpose of the present invention is to solve the technical problems existing in the prior art and to provide a method for obtaining a multi-level heterogeneous strengthening structure of an aluminum alloy.

[0006] To achieve the above object, the technical solution provided by the present invention is: a method for obtaining a multi-level heterogeneous strengthening structure of an aluminum alloy, comprising the following steps:

[0007] (1) Solution treatment: The aluminum alloy billet is heated to the solution treatment temperature, and the precipitate phase is completely dissolved to obtain a uniform solution state structure, and then rapidly cooled to obtain a solution state structure billet;

[0008] (2) Rapid heating and large deformation: The blank with the solid solution structure obtained in step (1) is rapidly heated to the deformation temperature, rapidly deformed without heat preservation, and rapidly cooled to obtain a sample with a non-steady-state structure composed of unstable precipitates and dislocation substructures that are conducive to aging;

[0009] (3) Aging treatment: Aging treatment is performed on the sample after rapid heating and large deformation in step (2), thereby forming a multi-level heterogeneous strengthening structure with precipitates of different sizes and coexistence of coarse grains and fine grains.

[0010] Preferably, the treatment temperature in step (1) is a temperature for complete solid solution.

[0011] Preferably, the rapid cooling in step (1) and step (2) is performed by water cooling or liquid nitrogen cooling.

[0012] Beneficial effects of the present invention:

[0013] The technical solution of the present invention can reduce the deformation resistance of the material and improve the deformation capacity of the material by assisting with transient rapid heating in the intermediate deformation stage during the implementation of the solid solution-rapid heating large deformation-aging process route. Compared with cold deformation, the non-steady-state rapid heating can be used to retain the strengthening structure formed in the solid solution process. At the same time, large deformation is conducive to the formation of substructures such as dislocations and grain refinement, promoting the precipitation of nanophases in the subsequent aging process, thereby forming a multi-level heterogeneous strengthening structure and improving the performance of the aluminum alloy. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The drawings described herein are used to provide further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0015] Figure 1 is a flow chart of the present invention;

[0016] Figure 2 It is the structure of the aluminum alloy after solid solution-insulation without deformation-aging in the present invention;

[0017] Figure 3 It is the structure of the aluminum alloy after solid solution-heating and heat preservation, large deformation-aging in the present invention;

[0018] Figure 4 It is the structure of the aluminum alloy after solid solution-rapid heating and large deformation-aging in the present invention;

[0019] Figure 5It is a performance comparison chart of different treatment systems in the present invention.

[0020] Figure annotation: DETAILED DESCRIPTION

[0021] This section will describe in detail the specific embodiments of the present invention. The preferred embodiments of the present invention are shown in the accompanying drawings. The purpose of the accompanying drawings is to supplement the description of the text part of the specification with graphics, so that people can intuitively and vividly understand each technical feature and the overall technical solution of the present invention, but it cannot be understood as a limitation on the scope of protection of the present invention.

[0022] Reference Figure 1-Figure 5 The preferred embodiment of the present invention is a method for obtaining a multi-level heterogeneous strengthening structure of an aluminum alloy, characterized in that it comprises the following steps:

[0023] (1) Solution treatment: The aluminum alloy billet is heated to the solution treatment temperature, and the precipitate phase is completely dissolved to obtain a uniform solution state structure, and then rapidly cooled to obtain a solution state structure billet;

[0024] (2) Rapid heating and large deformation: The blank with the solid solution structure obtained in step (1) is rapidly heated to the deformation temperature, rapidly deformed without heat preservation, and rapidly cooled to obtain a sample with a non-steady-state structure composed of unstable precipitates and dislocation substructures that are conducive to aging;

[0025] (3) Aging treatment: Aging treatment is performed on the sample after rapid heating and large deformation in step (2), thereby forming a multi-level heterogeneous strengthening structure with precipitates of different sizes and coexistence of coarse grains and fine grains.

[0026] The technical solution of the present invention can reduce the deformation resistance of the material and improve the deformation capacity of the material by assisting with transient rapid heating in the intermediate deformation stage during the implementation of the solid solution-rapid heating large deformation-aging process route. Compared with cold deformation, the non-steady-state rapid heating can be used to retain the strengthening structure formed in the solid solution process. At the same time, large deformation is conducive to the formation of substructures such as dislocations and grain refinement, promoting the precipitation of nanophases in the subsequent aging process, thereby forming a multi-level heterogeneous strengthening structure and improving the performance of the aluminum alloy.

[0027] Example 1

[0028] This embodiment is a method for obtaining a multi-level heterogeneous strengthening structure of an aluminum alloy. The material used is a rolled 2195 aluminum-lithium alloy thick plate, which is processed into a cylindrical sample with a specification of Φ8mm×12mm.

[0029] The specific implementation steps of this embodiment are:

[0030] (1) Solution treatment of 2195 aluminum-lithium alloy billet. The rolled 2195 aluminum-lithium alloy sheet was heated to 510°C and kept at this temperature for 70 minutes to obtain a solid solution structure with continuous static recrystallization; then it was rapidly cooled to obtain a solid solution structure billet;

[0031] (2) Rapid heating and large deformation compression: The solid solution structure of the blank in step (1) is rapidly heated to 400°C at a rate of 5°C / s on a Gleeble-3500 thermal simulation test machine, immediately compressed by 70%, and rapidly cooled, retaining the rapidly heated large deformation structure sample.

[0032] (3) Aging treatment: The sample in step (2) is kept at 155°C for 30 hours and then air-cooled for aging treatment, thereby obtaining a multi-level heterogeneous strengthening structure with precipitates of different sizes and coexistence of coarse grains and fine grains.

[0033] The present invention obtains a uniform solid solution structure by solution treatment of an aluminum alloy billet; then obtains a non-steady-state structure composed of unstable precipitation phases and dislocation substructures by rapid heating and large deformation; and forms a multi-level heterogeneous strengthening structure with precipitation phases of different sizes and coarse grains and fine grains by aging treatment. The present invention utilizes a process method of solution treatment-rapid heating and large deformation-aging to prepare a multi-level heterogeneous strengthening structure, thereby improving the mechanical properties of the aluminum alloy, such as hardness and strength.

[0034] Under the premise that no conflict occurs, those skilled in the art may freely combine and superimpose the above-mentioned additional technical features.

[0035] The above description is only a preferred implementation mode of the present invention. Any technical solution that achieves the purpose of the present invention by substantially the same means belongs to the protection scope of the present invention.

Claims

1. A method for obtaining a multi-level heterogeneous strengthening structure of an aluminum alloy, characterized in that: This includes the following steps: (1) Solution treatment: The 2195 aluminum-lithium alloy rolled plate is heated to 510°C and kept at this temperature for 70 minutes to obtain a solid solution structure of continuous static recrystallization, and then rapidly cooled to obtain a solid solution structure blank; (2) Rapid heating and large deformation: The solid solution structure obtained in step (1) is rapidly heated to 400°C at a rate of 5°C / s on a thermal simulation test machine, immediately compressed by 70%, and rapidly cooled to retain the rapid heating and large deformation structure; (3) Aging treatment: The rapid heating and large deformation structure obtained in step (2) is subjected to aging treatment, i.e., kept at 155°C for 30 hours and then air-cooled, thereby obtaining a multi-level heterogeneous strengthening structure with precipitates of different sizes and coexistence of coarse grains and fine grains.

2. The method for obtaining a multi-level heterogeneous strengthening structure of an aluminum alloy according to claim 1, characterized in that: The treatment temperature in step (1) is the temperature for complete solid solution.

3. The method for obtaining a multi-level heterogeneous strengthening structure of an aluminum alloy according to claim 1, characterized in that: The rapid cooling methods in step (1) and step (2) are both water cooling or liquid nitrogen cooling.

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