Microstructure and texture evolution during extrusion of 6xxx aluminum alloys with Mn/Zr additions
摘要
This study investigates the effects of the addition of Mn and Zr and the extrusion temperature on the microstructure and texture evolution of 6xxx aluminum alloys. Three experimental alloys, with individual and combined additions of Mn and Zr, are extruded at 400 °C and 500 °C to assess the dispersoid formation, grain structure evolution, and recrystallization behavior. The combined addition of Mn and Zr results in the formation of dual dispersoids (α-Al(MnFe)Si and Al3Zr), inhibiting dynamic recovery and recrystallization and exhibits the highest recrystallization resistance among the three alloys studied. Extrusion at 400 °C retains a higher portion of deformed grain structure, while extrusion at 500 °C generates more recrystallized grains. Texture analysis reveals the development of a β-fiber texture in all materials with a higher volume fraction of deformation textures for the MnZr alloy, indicating a greater resistance to recrystallization during extrusion. The peripheral coarse grain layer is significantly reduced in the MnZr alloy at 500 °C. After post-extrusion annealing, alloys extruded at 400 °C exhibit a higher degree of recrystallization than those extruded at 500 °C. At both extrusion temperatures, the MnZr alloy maintains superior recrystallization resistance owing to the reduced coarsening and higher number density of dispersoids.