Microstructure and texture evolution during hot deformation of cast-homogenized ZK60 magnesium alloy

Abstract

Forgeability of as-cast ZK60 magnesium alloy was investigated by isothermal uniaxial hot compression of cylindrical samples using the Gleeble® 3500 thermal-mechanical simulation testing system. Computational thermodynamics predictions (by FactSage™) along with differential scanning calorimetry (DSC) experiments showed incipient melting of low melting temperature precipitates in the as-cast material at around 340 °C. Therefore, the as-cast material was subjected to homogenization heat treatment at 400 °C for 4 h. Hot compression test were then conducted at 400 and 450 °C using a variety of strain rates (0.001–1.0 s−1). The microstructure of the samples deformed at low strain rates consisted of dynamically recrystallized (DRXed) grains. By increasing the strain rate, the volume fraction of the DRXed regions reduced. The material also exhibited sensitivity to deformation temperature in terms of DRX volume fraction. Texture of the deformed samples was also characterized using the XRD method to investigate the effect of hot deformation conditions on the texture evolution.