Hot deformation behavior and workability of pre-extruded ZK60A magnesium alloy

Abstract

The hot deformation behavior and workability of pre-extruded ZK60A magnesium alloy were investigated by compression tests in the temperature range of 250–450 °C and the strain rate range of 0.001–10 s−1. The constitutive equation for the pre-extruded ZK60A alloy can be described by hyperbolic sine function. Processing maps were constructed from true strains of −0.2 to −0.8. The alloy experienced complete dynamic recrystallization (DRX) and showed good workability in the temperature range of 300–400 °C and the strain rate range of 0.01–0.001 s−1, where hot working in pre-extruded ZK60A, such as forging, can be carried out. For large deformation to true strain of over −0.5, strain rates above 0.1 s−1 are not recommended at all temperatures, where flow instability such as local strain concentration, twinning deformation, abnormal grain growth, micro-cracks, and shear fracture were observed. Climb-controlled dislocation creep dominates both the plastic deformation and nucleation of DRX of the pre-extruded ZK60A magnesium alloy.