Effects of grain refinement and melt filtration on the mechanical properties of sand and permanent mold cast magnesium AZ91D alloy

Magnesium finds applications in a multitude of automotive, military and commercial applications because of its lightweight, high strength/weight ratio, high-castability and excellent damping capacity and machinability. Recognition by the auto industry of weight reduction, an increase in energy cost together with government regulations controlling vehicle design has established an environment for increased magnesium use. At present, most of the automotive components in Mg alloys are produced by high-pressure die-casting. However, to increase Mg usage in components, other casting processes such as sand and permanent mold casting should be evaluated. CANMET-Materials Technology Laboratory has taken this approach and initiated a research program to address critical issues relating to high integrity sand and permanent mold casting. As part of this research program, the effects of mold design, grain refinement and melt filtration on the mechanical properties of sand and permanent mold cast test bars were investigated. The effect of machining on properties was also evaluated. The experimental results are presented and discussed in this paper.