Effect of Mg on microstructures and properties of Al-Mg-Si-Cu alloys for automotive body sheets

摘要

The effects of variation of Mg content on microstructures, the tensile properties and the formability of Al-Mg-Si-Cu alloys for automotive body sheets were investigated by means of scan electron microscopy, optical metallographic analysis, tensile and Ericsson tests. The results show that for Al-Mg-Si-Cu aluminium alloys with excessive Si, with an increment of Mg content, the strength enhances, the specific elongation and Erisson values of alloys decrease, and the number of Mg_2Si constituent increases and that of Al(MnFe)Si type constituents reduces. Al-Mg-Si-Cu aluminium alloys with excessive Si for automotive body sheets can present obviously the paint bake hardenability during the paint bake cycle (i. e. artificial aging at 170 deg C for 30 min immediately after the solution treatment and quenching). Suitable Mg content should be controlled in the range of 0. 8 percent and 1. 2 percent(mass fraction).