Erosion of A356.2 alloy by SiO2 particles

Automatic moulding has been widely applied in the casting industry, but erosive wear of moulding dies occurs when being filled with SiO₂ sand. A356 alloys have often been used as the die material although their erosion behaviours are still unclear. In this investigation, SiO₂ sand erosion of A356.2 alloy in the as-cast, naturally aged and artificially aged conditions was studied by varying the impact angle and choosing two pressures (0.15 and 0.3 MPa) of compressed air to carry the sand particles. The results indicate typical ductile erosion behaviour in which the maximum erosion rate occurs at oblique impact angles of about 20° to 25°, although both ductile wear mechanisms and brittle cracking of eutectic Si particles are present. Despite the improvement of the mechanical properties, the erosion resistance of the naturally aged specimens is only compatible to that of the as-cast specimens, and the artificially aged specimens show the greatest erosion rate at an air pressure of 0.3 MPa. Erosion of the artificially aged specimens also leads to a softening effect by dissolution of the Mg₂Si particles.