A kind of method for preparing aluminum-lithium alloy superplastic sheet

Abstract

The invention discloses a method for preparing an aluminum-lithium alloy superplastic plate. The process route is as follows: a 2A97 aluminum-lithium alloy slab with a certain initial thickness is used as a raw material, and the slab is solid-dissolved at 460-540° C. for 0.5-4 hours, After water quenching, keep the temperature at 400°C for 8-48h, and then roll the alloy to 1.0-4.0mm. Compared with the traditional deformation heat treatment method, the present invention effectively solves the problem of easy cracking when rolling large-size plates by increasing the intermediate annealing temperature, and at the same time changes the traditional warm rolling to cold rolling by leaving 20% ​​to 30% of deformation. The rolling process improves the deformation energy storage of the alloy and solves the problem of low superplastic elongation of the sheet. For the first time, a large-scale superplastic sheet of 2A97 Al-Li alloy with good superplastic properties was prepared.

Description

technical field [0001] The invention belongs to the field of nonferrous metal material processing, and in particular relates to a method for preparing aluminum-lithium alloy superplastic plates. [0002] By adopting the method of the invention, the 2A97 aluminum-lithium alloy superplastic plate can be obtained, and the typical superplastic elongation rate is 560%-1070%. Background technique [0003] In the aerospace industry, reducing weight and increasing efficiency is an eternal theme. Every gram of weight reduction in the aircraft will produce considerable technical and economic benefits. 2A97 aluminum-lithium alloy is a new type of Al-Cu-Li alloy independently developed by my country. It belongs to the third generation of aluminum-lithium alloy and is an important lightweight structural material in the aerospace field. The modern aerospace industry requires lightweight, low-cost, and high-volume components. Applying superplastic technology to aluminum-lithium alloys ca...

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Problems solved by technology

[0005] (1) The existing process requires a short residence time between rolling passes, otherwise the plate is easy to crack during rolling, and it is only suitable for preparing small-sized samples on small-scale rolling in the laboratory

For example, when preparing 2A97 aluminum-lithium alloy superplastic plates under industrial equipment conditions, after preheating at 400°C for 1 hour, when rolling from 25 mm thick to 10 mm thick, when the rolling deformation is only 60%, the plate will appear serious. cracking, such as figure 1 As shown, it is impossible to continue rolling

This is mainly due to the slow adjustment of the roll gap of the large rolling mill and the excessive temperature drop of the sample due to the long stay

[0006] (2) The method of multi-pass turning rolling is difficult to be used in the preparation of large-size plates

Tests have shown that multi-pass turning rolling, which constantly changes the rolling direction during the rolling process, is an effective method to suppress cracking in plate rolling. Even if the direction of rotation is turned, it is often impossible to continue rolling due to the large temperature drop caused by the long residence time

[0007] (3) The use of intermediate annealing can solve the problem of sheet rolling cracking. In the existing process, the intermediate annealing temperature must be lower than 300°C to obtain a sheet with a superplastic elongation rate of more than 350%. The lower annealing temperature increases the cracking of the sheet. Tendency

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