Flow Behaviors and Corresponding Constitutive Equation of the Al–9.4Zn–1.9Mg–2.0Cu Alloy

Abstract

Isothermal compression tests of the Al–9.4Zn–1.9Mg–2.0Cu alloy were carried out at the temperature ranging from 300 to 460 °C and the strain rate from 0.001 to 10 s−1, and the deformation degree was 70%. Flow stress curves show that the flow stress decreases with the increasing deformation temperature and the decreasing strain rate. The measured flow stress was corrected because of the effect of friction. The corresponding corrected stress values are lower than measured stress values. The effect of friction is far greater when hot-deformations occurred at lower temperatures or higher strain rates. A constitutive equation considering the effect of strain on material constants (i.e. α, n, Q and A) are established based on the Arrhenius-type equation. Compared with the experimental results, the flow stresses calculated by the constitutive equation have a high precision with the correlation coefficient of 0.95. Results show that higher deformation temperatures and lower strain rates are beneficial for hot deformation of the Al–9.39Zn–1.92Mg–1.98Cu alloy.