| Summary: | As-extruded AZ31 magnesium alloy samples were compressed at ambient temperature and strain rates of 1000–3000 s−1. The fracture surfaces of cracked samples, the evolution of microstructures and macrotextures were detected. The received flow curves exhibit an abnormal behavior at strain rates above 1500 s−1. A strain constitutive model based on strain equivalent principle was applied to analyze the flow curves of the damaged samples. The results indicate that the abnormal flow behaviors of the fractured samples are related to the increasing area of crack surfaces, and kinetic energy during dynamic crack nucleation and propagation. The initiation of the micro-crack also causes obvious flow softening in the cracked samples. The shapes of flow stresses of the intact samples are affected by twinning. Keywords: Magnesium alloy, Flow behavior, Fracture, Micro-crack, Twinning
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