Hot deformation behavior and microstructural evolution of Al-Zn-Mg-0.25Sc-Zr alloy during compression at elevated temperatures

The hot deformation behavior of Al-Zn-Mg-0.25Sc-Zr alloy and its microstructural evolution were investigated by isothermal axisymmetric hot compression tests at temperatures from 340 to 500 °C and strain rates ranging from 0.001 to 10 s−1. The steady flow stress increased with increasing the strain rate or decreasing the deformation temperature, which can be described by a hyperbolic-sine constitutive equation with the deformation activation energy of 150.25 kJ/mol. The tendency of dynamic recrystallization enhanced at high deforming temperatures and low strain rates, which corresponded to low Z values. With decreasing Z value, the main softening mechanism of the alloy transformed from dynamic recovery to dynamic recrystallization, correspondingly, the subgrain size increased and the dislocation density decreased.