Effect of refractory aggregate shape on the porosity of A356 alloy castings in lost foam casting

In this paper, the relationship between the microstructure of coatings and the quality of castings in lost foam casting (LFC) process was investigated. The morphological studies of refractory aggregates were carried out by scanning electron microscopy (SEM). The 3D models of the coating were built based on the dimension data of the refractory aggregate to analyze the differences in microstructure. The coating model was used in finite element simulations to study the flow state of liquid decomposition products in coatings with different microstructures. At the same time, each coating sample was used in multiple casting experiments. Defects at specific locations of the castings were analyzed and statistically counted through optical microscopy. In conclusion, the combination of expanded graphite and bauxite clinker yields the best quality castings in A356 LFC.