Microstructure and mechanical properties of SPD-processed an as-cast AZ91D+Y magnesium alloy by equal channel angular extrusion and multi-axial forging

The aim of this work is to study the microstructure and mechanical properties of an as-cast AZ91D+Y magnesium alloy processed via two different severe plastic deformation techniques, equal channel angular extrusion (ECAE) and multi-axial forging (MAF). The grains were significantly refined after only one pass for both ECAE and MAF processed billets. However, the homogeneity of the SPD-processed microstructure increased with increasing number of passes. Micro-hardness and tensile tests showed that billets processed by ECAE and MAF techniques followed a same behaviour. With the increase of the number of processing passes (accumulated strain), the values of micro-hardness, yield strength, ultimate tensile strength and elongation were observed to increase. Grain refinement caused by dynamic recrystallization was introduced to explain the effects of the number of processing passes (accumulated strain) on the microstructure and mechanical properties of AZ91D+Y magnesium alloys processed by ECAE and MAF techniques.