Dynamic Recrystallization and Grain Refinement in Extruded AZ31 Rod During Hot Torsion Deformation at 150 °C

The dynamic recrystallization mechanism and microstructure evolution in an extruded AZ31 rod during hot torsion deformation at 150 °C were investigated. It indicated that several dynamic recrystallization mechanisms were initiated during hot torsion deformation, including discontinuous DRX (DDRX), continuous DRX (CDRX) and twinning induced DRX (TDRX). With increasing strain, CDRX became the dominant DRX mechanism and contributed to a remarkable refinement of grains. A gradient distribution of dynamic recrystallization grains on the cross section of samples generated due to the gradient shear strain in twisted samples. Hot torsion can also arouse the c-axis of grains to rotate towards the extrusion direction. From low strain to high strain, the recrystallized grains exhibited a similar texture development with the deformed grains. The relevant mechanisms were revealed.