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

• Published in: Metals (Basel ) 2012-09, Vol.2 (3), p.292-312
• Main Authors: Rao, Kamineni Pitcheswara, Prasad, Yellapregada Venkata Rama Krishna, Dzwonczyk, Joanna, Hort, Norbert, Kainer, Karl Ulrich
• Format: Article
• Language: English
• Subjects: AZ31 magnesium alloy; Compacting; Cross slip; Deformation; Deformation mechanisms; Dynamic recrystallization; Efficiency; extrusion temperature; fiber texture; Grain boundaries; Grain size; kinetic analysis; Magnesium alloys; Magnesium base alloys; Process mapping; processing maps; Self diffusion; Temperature; Texture
• ISSN: 2075-4701; 2075-4701
• DOI: 10.3390/met2030292

The hot deformation characteristics of AZ31 magnesium alloy rod extruded at temperatures of 300 °C, 350 °C and 450 °C have been studied in compression. The extruded material had a fiber texture with parallel to the extrusion axis. When extruded at 450 °C, the texture was less intense and the direction moved away from the extrusion axis. The processing maps for the material extruded at 300 °C and 350 °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 °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 fiber texture with extrusion temperature. Highly intense texture, as in the rod extruded at 350 °C, will enhance the occurrence of prismatic slip in domains #1 and #2 and promotes pyramidal slip at temperatures >450 °C (domain #3).