The high temperature flow behavior modeling of AZ81 magnesium alloy considering strain effects

In the field of deformation process modeling, constitutive equations are invariably used as a calculation basis to estimate the materials flow responses. Accordingly, in the present study, a constitutive analysis has been conducted on the AZ81 magnesium alloy employing experimental stress–strain data obtained from isothermal hot compression tests. These tests had been done in the temperature range of 250–450 °C under strain rates of 0.003, 0.03 and 0.3 s−1. The effects of the temperature and strain rate on hot deformation behavior have been expressed in terms of an exponent-type Zener–Hollomon equation. Furthermore, the influence of strain has been included in the constitutive equation by considering its effect on different material constants. Consequently, a model to predict the high-temperature flow behavior of AZ81 magnesium alloy has been established. The true stress–true strain curves predicted by the extracted model are in good agreement with the experimental results, thereby confirming the validity of the developed constitutive relation.

► Developing strain-dependent constitutive equations to predict flow stress of AZ81.
► Employing hyperbolic sine-type equation for formulating hot compression results.
► Material constants are functions of strain.
► Excellent predictability of developed relation by comparing with experimental data.