Shear deformation and grain refinement during accumulative back extrusion of AZ31 magnesium alloy

The accumulative back extrusion (ABE), as a new-noble severe plastic deformation (SPD) technique, has been employed to clarify the microstructural evolutions of AZ31 magnesium alloy during severe deformation. The latter has been explored using a 3D finite element analysis along with the microstructural investigations. The distribution of ABE generated shear strain (SS) and its corresponding microstructures have been thoroughly studied. The results indicated that the restrictions of material flow during ABE processing had been led to the mechanical shear bands generation in the microstructure. In addition, the occurrence of continuous dynamic recrystallization (CDRX) within the bands has resulted in a local grain refinement in those areas. Consequently a bimodal structure including the fine recrystallized grains along with the elongated ones has been developed. The effect of deformation mode on the microstructural refinement has been also discussed through considering the developed SS history and the related microstructural refinement.