Failure prediction of magnesium alloy sheets deforming at warm temperatures using the Zener-Holloman parameter

In the present study, a new method of predicting fracture in magnesium alloy sheet deforming under warm-working conditions has been developed. The effects of temperature and strain rate have been incorporated into the ductile fracture criteria by formulating the damage growth resistance as a function of strain rate and temperature based on the finding of correlation between the fracture strain (or fracture work) obtained from a series of uniaxial tensile tests performed over wide ranges of temperature and strain rate and the Zener-Holloman parameter. Comparison between the maximum drawing depths in cup deep-drawing tests predicted by the finite element code coupled with the fracture criteria and the experimental data indicates that the newly developed fracture criteria may be quite useful in predicting the fracture behavior of magnesium sheets during non-isothermal forming. The proposed failure models are simple and readily applicable to other metallic alloys at elevated temperatures.