Mechanical characterisation of Mg alloys and model parameter identification for sheet forming simulations

The understanding of forming process of Mg alloys at elevated temperatures can be enhanced with help of numerical simulations. As such a constitutive model was implemented in a finite element frame work. For calibration of the constitutive response mechanical characterisation of Mg alloys were performed. The mechanical characterisation employed uni-axial tensile tests of two Mg alloys, namely AZ31 and ZE10 in heat treated condition, at room temperature (RT) and 200°C. The uni-axial tensile test at 200°C compared to those at RT revealed an increase in ductility but also a decrease in yield strength. Planar anisotropy was recorded in terms of differences in yield stresses as well as r-values between three different material orientations. It was also observed that the planar anisotropy is affected by the test temperatures. The r-values, especially at 200°C, found to be dependent on the accumulated strain. This observation is contrary to the usual practice of assuming a constant r-value. Using the test results the constitutive model parameters were identified.