Deformation homogeneity in accumulative back extrusion processing of AZ31 magnesium alloy

The ultra-fine grained materials produced by severe plastic deformation (SPD) methods have been widely investigated in the last decades due to the enhanced material properties such as improved tensile strength, hardness, toughness, fatigue life, and the optical and electrical related properties. The microstructure and mechanical properties of the deformed materials are strongly dependent on the amount and the homogeneity of strain achieved during the SPD processes. Accumulative back extrusion (ABE) method is a novel severe plastic deformation (SPD) technique which has been recently developed for fabrication of bulk ultra-fine structured materials. The knowledge of strain distribution and deformation behavior during ABE processing may assist the better understanding of the whole process. Therefore the present work has been conducted to examine the strain distribution and deformation behavior during ABE process through applying 3D finite element simulations with Abaqus/Explicit for different stages of deformation. In order to validate the simulation results, a grid method assessment was employed. The results demonstrated that a homogenous equivalent plastic strain of 4–5 has been gained after applying one pass ABE. In addition the results indicate that the distribution of normal strain is inhomogeneous. The microstructural observations have revealed a proper structural homogeneity after completion of an ABE cycle.

Research highlights▶ An amount of effective strain of 4–5 is applied during ABE. ▶ Strain distribution tends to be reasonably homogenous by applying the second step. ▶ Adequate plastic zone was believed to assist generating more homogenous deformation. ▶ Strain measurements by grid method present a good conformity with FEM results.