Impact of pre-straining on the hardness and anisotropic mechanical behavior of ZK61 Mg alloy

In this study, an extruded ZK61 magnesium alloy was subjected to heat treatment (510 °C/3h and 120 °C/24 h) and fabricated a bimodal strong basal textured ZK61 magnesium alloy (denoted as ZK61-T6 Mg alloy). Later, it was subjected to pre-compression first along with extruded direction and then along with transverse direction up to a fixed strain ~0.1 (hereinafter referred as ZK61-A Mg alloy), which developed basal and prismatic textures validated by X-ray diffraction analysis. The large fraction of twin induced deformation causes the grain refinement by dividing the parent grains into sub-grains through twin boundaries. The tensile yield strength to the compression yield strength ratio of ZK61-T6 Mg alloy and ZK61-A Mg alloy was found ~1.6 and ~0.84, respectively. The nearly symmetric yielding behavior in ZK61-A Mg alloy was attributed to texture changes and twinning induced grain refinement hardening effect. The strain hardening plateau regime under tensile loading of ZK61-A Mg alloy revealed the de-twinning phenomenon which increased the ultimate tensile strength. Our results also displayed an increase in Vickers micro-hardness ~26.7% of the ZK61-A Mg alloy.