Multi-temperature equal channel angular pressing of Mg-3 wt%Al-1 wt%Zn alloy

Abstract

Grain refinement of magnesium alloys at temperatures below 200 °C via deformation processes is a challenging task. Equal channel angular pressing is one of the severe plastic deformation techniques which can significantly refine grain size. Refined grains consequently improve mechanical properties of magnesium alloys. In this paper, Mg-3 wt%Al-1 wt%Zn magnesium alloy was processed by different multi-temperature equal channel angular pressing cycles without backpressure. The lowest finishing temperature of equal channel angular pressing was 150 °C leading to fine-grained microstructure with sporadically large elongated grains. Shear bands were observed after equal channel angular pressing finishing at temperatures of 175 and 150 °C. Electron backscattered diffraction revealed that grain boundary distribution is qualitatively the same for all equal channel angular pressing cycles. Crystallographic analyses of large elongated grains showed that {0 0 0 1} and {} planes in these grains tend to be aligned parallel to the shear plane. Microtexture measurements showed split of (0 0 0 2) poles. The shape of stress–strain curves and consequently yields tensile strength of Mg-3 wt%Al-1 wt%Zn alloy after multi-temperature equal channel angular pressing was influenced by final texture and twinning.