Due to their high strength-to-weight ratio, magnesium alloys (Mg) offer a favored alternative to steels and aluminum alloys for engineering components in the transportation industry. The application potentials are, however, impeded by poor room temperature formability and strong directional anisotropy. At room temperature, an insufficient number of slip systems are activated, thus plastic deformation is also accommodated by twinning. Due to its’ polar characteristic, the type of the nucleate twin, {10-12} extension or the {10-11} contraction type-twin, depends on the texture with respect to the loading direction. In turn, twinning was found as the key role for the tension–compression yield asymmetry, where Tensile yield strength (TYS) differs significantly from the Compressive yield strength (CYS) along the same direction. This asymmetry restricts the structural application of magnesium alloy, especially for beams subjected to tension and compression simultaneously.
Current research deals with the yield response of hot-extruded Mg-ZM21 alloy at a temperature of 190, 220 or 350℃ with a constant extrusion ratio. This is carried out through a comparative study consist of uniaxial tension and compression experiments. The inter-connection between asymmetry ratio (CYS/TYS) to microstructure phenomena and texture modification is carried out through the characterization at different extruded conditions. The microstructural and micro-textural investigations is carried out by means of Electron Back-Scattered Diffraction (EBSD) technique. Macro-texture analysis is carried out using X-Ray diffractometer, applying the Schultz reflection method. The MTEX package, a freely available MATLAB toolbox, is employed for the post-processing and the visualization of EBSD data. Qualitative intra-grain strain analysis and recrystallization fraction at different thermo-mechanical states are performed based on the local misorientation approach using kernel-average misorientation (KAM) maps and the grain-orientation spread (GOS) plots.
