Temperature and strain rate effect incorporated failure criteria for sheet forming of magnesium alloys

As formability of magnesium alloys is highly dependent upon temperature and strain rate at elevated temperatures, a new approach of incorporating strain rate and temperature effects into a failure criterion is necessary. In the present study, two failure criteria were proposed to predict the fracture behavior of magnesium alloy sheets deforming at elevated temperatures. The two failure criteria were developed based on the effective strain or damage parameters and both could be formulated as a function of Zener-Holloman parameter. The experimental data obtained from the series of tensile tests conducted in wide range of temperature and strain rate were used to find the correlation between the damage value at fracture (or fracture strain) and Zener-Holloman parameter. Comparison between the experimental results and the prediction by FEM incorporated with the failure criteria indicated that the proposed criteria were useful in predicting the fracture behavior of magnesium alloy sheets deforming during deep drawing process.