Effect of heat treatment on strain hardening of ZK60 Mg alloy

Strain hardening behaviors of extruded ZK60 Mg alloy under different heat treatments (T4, T5 and T6) were studied using uniaxial tensile tests at room temperature. Hardening capacity, strain hardening exponent as well as strain hardening rate curve were obtained according to true plastic stress–strain curves. T5 and T6 treatments decrease strain hardening of extruded ZK60 alloy, and subsequently give rise to an obvious reduction in tensile uniform strain. While, as-T4 treated specimen shows the strongest strain hardening ability among these specimens, and its hardening capacity and strain hardening exponent are nearly twice those of as-T5 and T6 treated specimens. These effects were analyzed in terms of the microstructural variation and dislocation storage in ZK60 alloy.