Investigation of the effect of strain rate and temperature on the deformability and microstructure evolution of AZ31 magnesium alloy

Magnesium, being the lightest available structural material, is a primary candidate for automotive and aviation industries; however, the difficulty of deforming magnesium is a limiting factor. This research work aims to investigate the deformability of AZ31 magnesium alloy employing various deformation conditions. The results are used to correlate the effect of changing the deformation conditions on the resulting material behavior and microstructure. Tensile testing experiments were conducted at a wide variety of deformation conditions to determine the constitutive behavior of AZ31 magnesium alloy. The effect of changing the deformation conditions on the resulting microstructure is also examined and quantified by measuring the volume fraction and size of the dynamically recrystallized grains. Hardness measurements were employed to determine the softening behavior of the material during deformation due to dynamic recrystallization. The findings indicate a decrease in the peak stress and hardness and an increase in the fraction and size of dynamically recrystallized grains with decreasing strain rate and increasing deforming temperature. Temperature plays a major role in determining the fraction and size of dynamically recrystallized grain whereby, at a certain strain rate, an increase in temperature by 50 °C results in a change in the fraction of dynamically recrystallized grains by ∼30%. Further correlations were developed based on these findings to optimize the deformation behavior.