Effect of test temperature on flow behavior and strain hardening of magnesium under high strain rate deformation conditions

Abstract

Pure magnesium sheet with a grain size of 45 μm was produced by hot rolling and annealing at 350 °C for 1 h. The effect of strain rate (10−2 s−1, 10−1 s−1 and 103 s−1) and test temperature (25 °C, 100 °C and 300 °C) on work hardening behavior of annealed magnesium was investigated. With increase in strain rate, work hardening rate increases significantly at all temperatures. With increase in test temperature, work hardening rate showed a transition from twin to dislocation controlled plasticity. Under high strain rate test conditions an increase in flow stress was noticed with an increase in test temperature during initial strain regime up to the onset of flow softening. This is attributed to strain rate and temperature dependent contribution of twin induced texture change and subsequent dislocation activity. A physics based model to describe strain rate and temperature dependent flow behavior is discussed.