Hot deformation behavior and optimization of processing parameters of a typical high-strength Al-Mg-Si alloy

In this study, the hot compression tests of 6X82 aluminum alloy were carried out at the deformation temperature range of 300-500 degrees C and strain rate range of 0.01-10 s(-1) on a Gleeble-3500 thermal-mechanical simulator to reveal the hot deformation behavior and obtain the optimum processing window of the alloy via analysis of flow curves, constitutive equation, processing map (PM) and microstructure characteristic. The results show that the flow stress depends strongly on the deformation temperature and strain rate, and both the flow stress and the initial peak-stress strain (onset of dynamic recrystallization (DRX)) decrease with the increase of temperature and decrease of strain rate. The estimated activation energy in the constitutive equation is 224.738 kJ . mol(-1) and indicates that the DRX should be the softening mechanism of the alloy, which was also confirmed by the microstructure observation of the deformed specimens. The constituted PM exhibits two deterministic domains of domain 1 (320-360 degrees C/0.07-0.26 s(-1)) and domain 2 (465-535 degrees C/0.09-1.2 s(-1)), where the specimen deformed in domain 2 exhibits a typical DRX microstructure with more fine grains than that of the domain 1 and thus the domain 2 is proposed to be the optimum processing window of the 6X82 aluminum alloy. (c) 2015 Elsevier Ltd. All rights reserved.