Hot Deformation Mechanisms in AZ31 Magnesium Alloy Extruded at Different Temperatures: Impact of Texture

The hot deformation characteristics of AZ31 magnesium alloy rod extruded at temperatures of 300 degrees C, 350 degrees C and 450 degrees C have been studied in compression. The extruded material had a fiber texture with <10<(1)over bar>0> parallel to the extrusion axis. When extruded at 450 degrees C, the texture was less intense and the <10<(1)over bar>0> direction moved away from the extrusion axis. The processing maps for the material extruded at 300 degrees C and 350 degrees C are qualitatively similar to the material with near-random texture (cast-homogenized) and exhibited three dynamic recrystallization (DRX) domains. In domains #1 and #2, prismatic slip is the dominant process and DRX is controlled by lattice self-diffusion and grain boundary self-diffusion, respectively. In domain #3, pyramidal slip occurs extensively and DRX is controlled by cross-slip on pyramidal slip systems. The material extruded at 450 degrees C exhibited two domains similar to #1 and #2 above, which moved to higher temperatures, but domain #3 is absent. The results are interpreted in terms of the changes in <10<(1)over bar>0> fiber texture with extrusion temperature. Highly intense <10<(1)over bar>0> texture, as in the rod extruded at 350 degrees C, will enhance the occurrence of prismatic slip in domains #1 and #2 and promotes pyramidal slip at temperatures >450 degrees C (domain #3).