Pre-aging on early-age behavior and bake hardening response of an Al-0.90Mg-0.80Si-0.64Zn-0.23Cu alloy

Pre-aging on early-age behavior and bake hardening response of an Al-0.90Mg-0.80Si-0.64Zn alloy was investigated by differential scanning calorimetry (DSC), high resolution transmission electron microscopy (HRTEM), 3-dimensional atom probe (3DAP), Erichsen test and tensile test. The results indicated that pre-aged alloy exhibited excellent formability and bake-hardening response, while bake hardening response was poor in samples with natural aging. Clustering behavior during natural aging was inhibited by pre-aging. Numerous GP zones formed in pre-aged samples. GP zones were the nuclei of beta '' precipitates or directly transformed beta '' phases during paint baking process. A large number of beta '' phases were observed in pre-aged samples after paint bake treatment. There was no sign to indicate that beta '' phase precipitated in natural aged samples after bake hardening treatment. (C) 2016 Chinese Materials Research Society. Production and hosting by Elsevier B.V.