A kind of aluminum alloy sheet for automobile body and preparation method thereof

Abstract

The invention discloses an aluminum alloy sheet for automobile body and a preparation method thereof. The sheet includes: Si: 0.8wt.%-1.2wt.%; Mg: 0.3wt.%-0.8wt.%; Zn: 0.4wt.%. ~0.8wt.%; Cu: 0.1wt.%~0.3wt.%; Mn: 0.05wt.%~0.2wt.%; Fe: ≤0.3wt.%, Zr: 0.05‑0.15%, the balance is Al and The content is less than 0.05wt.% impurity. The preparation method includes: melting and casting, homogenization, hot rolling, cold rolling, intermediate annealing, solid solution, straightening, primary pre-aging, and secondary aging. The alloy of the invention has higher baking hardening performance, can significantly improve the baking paint strength of the plate under the premise of ensuring a low initial yield strength of the plate, and can simultaneously ensure the hemming performance and surface quality of the plate.

Description

technical field [0001] The invention relates to the technical field of aluminum alloy materials, in particular to an aluminum alloy plate for automobile body and a preparation method thereof. Background technique [0002] Automobile lightweight is not only a more economical and effective means to achieve energy saving and emission reduction, but also helps to improve safety performance and driving performance. As a good lightweight material, the application of aluminum alloy sheets in automobiles is gradually increasing. [0003] In addition to good surface quality (no paint brush line defects), flanging performance, and mechanical properties, the 6xxx series aluminum alloys used for automotive body outer panels also require high bake hardening properties. This is because the high bake hardening performance can ensure that the material rapidly rises from the low yield strength at the time of delivery to the high yield strength during the coating and baking process, so as to...

AI Technical Summary

Problems solved by technology

For example, in terms of how to improve the bake hardening performance of alloys, patents CN201010199924.0, CN201410283404.6, CN201410064892.1 etc. achieve high paint hardening effects by adding alloy elements such as Cu and Zn to conventional 6xxx series aluminum alloys; patent CN200810194841.5 , CN200710190078.4 and patent CN201711217322.1, by controlling the preheating process after solid solution water quenching of the plate, the bake hardening performance of the plate is improved, but the effect is not obvious; in the CN201480008337.5 patent, it is mentioned that a The ratio of the total number of Mg and Si atoms in the measured atomic clusters to the total number of solute atoms in the matrix is ​​controlled at 10%-30%, so that the strength before baking and the BH response are simultaneously improved.

The specific method is to carry out the first-stage reheating treatment at 100-250°C for about 2 minutes after solution quenching, and then carry out the second-stage heating at 70-130°C for several hours. Larger improvement, but the initial yield strength is higher, which is not conducive to sheet metal stamping

Images