Flow Behavior and Microstructure of 7A85 Aluminum Alloy During Hot Compression
QIU Li-li1, GAO Wen-li1, LU Zheng2, FENG Zhao-hui2
1. College of Materials Science and Engineering, Hunan University, Changsha 410082, China;
2. Beijing Institute of Aeronautical Materials, Beijing 100095, China
Abstract：The flow stress behavior and the microstructure evolution of as-cast 7A85 aluminum alloy were studied by the hot compression test, which was performed on Gleeble-3500 thermal simulation machine at 300-450℃ and strain rate 0.01-10s-1. The results show that the true stress is rising to peak stress rapidly in the initial deformation period, then the flow stress decreases due to dynamic recovery and dynamic recrystallization, finally the flow stress tends to be stable. The peak flow stress increases with decreasing deformation temperature and increasing strain rate. It can be described by Zener-Hollomon parameter. The constitutive equation of 7A85 aluminum alloy is obtained by linear regression, and the hot deformation activation energy Q is 253.68kJ/mol. With the decreasing of lnZ, the grains are elongated radially, the sub-grains grow up, the dislocation density and the quantity of second phase particles decrease. The softening mechanism is mainly dynamic recrystallization.
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2016, Vol. 44 
