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

Abstract

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.