Effect of Dynamic Recrystallization on Grain Refinement during Interactive Alternating Forward Extrusion of AZ31B Magnesium Alloy

摘要

The dynamic recrystallization mechanisms leading to grain refinement in an extruded AZ31 rod during interactive alternating forward extrusion were investigated. Several dynamic recrystallization mechanisms were initiated due to extrusion deformation, including discontinuous dynamic recrystallization, continuous dynamic recrystallization (CDRX), and twinning-induced dynamic recrystallization. The microstructure of the AZ31 magnesium alloy formed at 350 degrees C exhibited the most uniform grain distribution, smallest grain size, and roundest grains compared to the samples formed at other temperatures. Furthermore, this sample exhibited the highest average Schmidt factor and hadsoftly orientated grains. The CDRX behavior is particularly significant, where a large number of regions exhibited continuous rotation of grains and the merging of sub-grains. This which led to uniform structure distribution and the improvement of the grain roundness. The prismatic slip system and the pyramidal slip system play an obvious role of the magnesium alloy grains in grain deflection. It provides scientific guidance for the formulation of interactive alternating forward extrusion process and the control of microstructures.