Influence of Initial Microstructure on the Hot Deformation Behavior of AZ80 Magnesium Alloy

This research studies the hot deformation behavior of cast and extruded AZ80 magnesium alloys for forging applications. Uniaxial hot compression tests were carried out at a temperature of 400 °C and strain rates ranging from 0.001 to 0.1 s, to various strain levels up to a true strain of 1. Detailed microstructure and texture characterizations of the deformed samples were performed using electron backscatter diffraction and x-ray diffraction techniques. The results show that multiple dynamic recrystallization (DRX) mechanisms were simultaneously active in both starting materials at all the tested deformation conditions, resulting in significant grain refinement. Cast and extruded samples showed the development of a similar microstructure, texture, and flow stress by a strain of 1, despite having very different starting microstructures. This was investigated by considering differences in DRX mechanisms and kinetics, and relative deformation mode activities. Since industrial forgings typically involve strains much higher than 1, comparable final microstructure and texture are expected in industrial-scale forgings of AZ80 at 400 °C, irrespective of the starting material state.