An investigation on microstructural and mechanical properties of solid mould investment casting of AZ91D magnesium alloy

In this work, AZ91D magnesium alloy was cast in solid plaster mould using vacuum assistance. The influence of process parameters and wall thickness on the microstructure and tensile properties of cast specimens was studied. Within the range of experimental parameters, it was found that casting and mould preheating temperatures have minor influence on mechanical properties. However, gating design proved to affect the microstructure and tensile properties of cast specimens. Compared to bottom filling, top filling led to casting defects that seriously impaired the mechanical properties. Generally, tensile properties increased with a decrease of section thickness, this improvement being explained by a reduction of dendrite arms spacing and grain size. Finally, the mechanical properties of solid mould investment cast specimens were compared with those obtained by foamed plaster casting, sand casting, permanent mould casting and die-casting.