Effect of microstructure on mechanical properties for A356 casting alloy

Abstract

A quantitative study of the relationship between microstructural features such as secondary dendrite arm spacing (DAS), eutectic structure and mechanical behaviours of A356 casting alloys has been conducted. In the condition of minimising casting defects, the influence of microstructural features on the mechanical performance becomes more pronounced. Depending on the cooling rate affecting the primary and eutectic microstructure, the tensile properties were changed upon experimental conditions, i.e. both of tensile strength and elongation were increased with decreasing DAS, also the results were the same at high temperatures. The increase in both of room temperature high cycle fatigue and high temperature low cycle fatigue lives with decreasing DAS was observed, mainly due to homogeneous deformation owing to the fine size of eutectic silicon and Fe intermetallic particles. The observation of fracture surfaces was conducted to find the effect of microstructure on mechanical properties by a scanning electron microscope.