Dependence of tensile properties of AM60 magnesium alloy on microporosity and grain size

The effect of microporosity on the tensile properties of a high-pressure die-cast and a gravity-cast AM60 alloy was investigated along with their dependence on the variation in grain size, with a theoretical prediction based on a constitutive model. The strain rate sensitivity of as-cast AM60 alloy was measured through an incremental strain rate change test at room temperature, and the microporosity was measured through quantitative fractography analyses on the fractured surface. The yield strength of the AM60 alloy is linearly dependent on the microporosity variation that increases remarkably with the increase of grain size. The UTS and elongation have a strong dependence upon the variation in microporosity, showing an inverse parabolic relationship. Their dependence on microporosity becomes more and more sensitive with the increase in grain size. The tensile properties of the AM60 alloy are significantly affected by the variation in the strain-hardening exponent in terms of a nominal range of grain size, even though they depend fundamentally upon the variation of the load-carrying capacity.