Effect of intermediate annealing on microstructure and properties of Al-Mg-Si series aluminum alloy automobile sheet

doi:10.13251/j.issn.0254-6051.2020.10.024

Abstract

Abstract: Effect of different intermediate annealing (IA) treatment, i.e. without IA, IA at 300 ℃ for 2 h and at 420 ℃ for 2 h, on the Al-Mg-Si series alloy sheet was investigated by means of optical microscopy observation, XRD analysis, TEM analysis, Topology instrument inspection and tensile test. The results indicate that IA treatment has obvious effect on the microstructure, texture, roping line and mechanical properties of the T4P treated sheets. Increasing the IA temperature is beneficial for obtaining equiaxed grains, increasing strain hardening exponent (n value) and reducing anisotropy (Δr value). But the average Lankford coefficient (r value) decreases. Furthermore, the sheet which IA at 300 ℃ for 2 h has the best surface quality after 10% prestretching, but the sheet without IA or IA at 420 ℃ for 2 h have a horrible roping line after pre-stretching. These differences can be attributed to the microstructure and texture transformation during the IA treatment. It can be concluded that the IA treatment of 300 ℃×2 h is better for the comprehensive performance of the Al-Mg-Si series alloy sheet.

Key words: Al-Mg-Si series alloy, automobile body sheet, roping line, mechanical properties, intermediate annealing

CLC Number:

TG146

Liu Xiaoteng, Zhao Jialei, Sun Youzheng, Cheng Rence, Lü Zhengfeng, Zhao Guoqun. Effect of intermediate annealing on microstructure and properties of Al-Mg-Si series aluminum alloy automobile sheet[J]. Heat Treatment of Metals, 2020, 45(10): 119-123.

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