Research on Bake Hardening Behavior of AA6016 Aluminum Alloy Sheets

The mechanical property and bake hardening behavior of two new-type automotive body AA6016 aluminum alloys under different artificial ageing processes are investigated comparatively,and the interrelated micro-mechanism is discussed.The optimal process is as follows:Solution hardening + pre-ageing + natural ageing + artificial ageing(bake hardening),which conduces to strengthening bake hardening.The results indicate that the bake hardening of aluminum alloy is mainly caused by the metastable precipitation of β′′ phase and the dislocations strengthening resulting from pre-deformation.The BH value is insensitive to natural ageing and rolling conditions,which couples with the speed of β′′ phase nucleation.The short-time baking process with high-temperature(2%～3% pre-deformation,170～180 ℃,less than 30 min) contributes to obtaining good bake hardening properties,the yield stress enhances 40～90 MPa.It is a good treatment schedule to promote the bake-hardening and formability of AA6016 aluminum alloys,which has guiding significance to practical application by enterprises.