Hot compressive flow stress modeling of homogenized AZ61 Mg alloy using strain-dependent constitutive equations

The experimental stress–strain data from hot compression tests were used to establish constitutive equations in a homogenized cast AZ61 Mg alloy. Hot compression tests were conducted using the Gleeble 3500 thermal simulation machine in the temperature range of 250–450°C and strain rate range of 1×10−3–1s−1. The constitutive analysis was performed based on the effect of strain on the constitutive parameters. Constitutive equations as a function of strain were constructed according to the hyperbolic sine constitutive law. The correlation between the strain-dependent constitutive parameters and flow behavior was analyzed. Results showed that variations in the constitutive parameters with strain were associated with the stress–strain behavior. A comparatively higher scattering was obtained at low strains based on the constitutive equation with the strain-dependent stress multiplier (α) determined by power and exponential laws. However, the constitutive analysis with a constant α determined by the hyperbolic sine constitutive equation showed better estimations between the calculated and experimental flow stresses at different temperatures and strain rate conditions used in this study.