Dynamic and static softening behaviors of aluminum alloys during multistage hot deformation

The dynamic and static softening behaviors during multistage hot deformation of aluminum alloys (1050, 5182 and 7075 alloys) have been studied by isothermal interrupted hot compression tests in 300 and 400 °C at a strain rate of 0.5 s−1 on Gleeble 1500. The interrupted deformations were conducted with delay times varying between 30 and 120 s after achieving a strain of approximately 0.4 in the first stage. It was indicated that the considerable dynamic softening and exceptional softening associated with a structure softening exist in both 1050 and 7075 alloy deformation at 400 °C, leading to an initial flow stress value at the second deformation lower than that at the first deformation. For all alloys studied, the static softening increases with increasing deformation temperature and holding temperature and delay times, but the increment for 5182 alloy is much higher than that for both 1050 and 7075 alloys in the same hot deformation conditions.