Effect of ECAP temperature on the microstructure, texture evolution and mechanical properties of pure magnesium

Abstract

Abstract Equal channel angular pressing (ECAP) by route-A is considered to be the most effective severe plastic deformation technique for hexagonal closed packed magnesium to obtain ultra-fine grain size. In this work, ECAP by route-A was carried out up to eight passes by reducing deformation temperature after each pass. The 8th pass ECAP could be processed successfully at 473 K, 423 K, and 300 K without fracture. The microstructure and texture evolution were investigated using electron-backscattered diffraction in a scanning electron microscopy to understand the (i) deformation behaviour, (ii) dynamic recrystallization mechanisms, and (iii) impact on the mechanical properties. The smaller grain size was obtained for the low-temperature ECAP. Grain refinement by the occurrence of continuous dynamic recovery and recrystallization, as well as discontinuous dynamic recrystallization, were observed attributing to the anisotropy in stacking fault energy. The texture remained unaltered concerning the temperature difference, indicating the deformation mechanism remained unchanged and remained slip dominated, which is desirable. As the grain size reduces, the ambient temperature compressive mechanical behaviour changes from sigmoidal to parabolic. This indicates a change in the deformation behaviour from twin to slip induced as the grain size decreases.