Constitutive prediction and dependence of tensile properties of high-pressure die-cast AM60B and AZ91D magnesium alloy on microporosity

The effect of micro-voids on the tensile property of high-pressure die-cast AM60B and AZ91D magnesium alloy was investigated through systematic experimental approaches, with a constitutive prediction on the load carrying capacity and strain-related factors. The strain rate sensitivity was measured through the incremental strain rate change test, and the microporosity was measured from a comparison between the area of the micro-void and the cross-section area through the quantitative fractography on a fractured surface. The yield strengths of the AM60B and AZ91D alloys exhibit a linear dependence upon the variation of microporosity. In addition, the UTS and elongation of both alloys have a strong dependence upon the variation of microporosity, with an inverse parabolic relationship. The constitutive prediction exhibits is in good agreement with overall trend of the tensile properties of both alloys. From the constitutive prediction, it is confirmed that the differences in the UTS and elongation of both alloys arises from the divergence of the strain hardening ability, rather than from the strain rate sensitivity.