Thermal Treatment Technic for Granulation of Eutectic Si Phase in Low Temperature or Short Term of Al-8%Si Alloy Thin Casting

Abstract

  Currently, automobile bodies and frames are increasingly being manufactured using hypo-eutectic Al-Si alloy die casting. However, since cast products are thin, it is difficult to deal with distortion during heat treatment. One potential method of resolving this is to carry out heat treatment at a low temperature for a short time. Therefore, in this study, we attempted to clarify the effects of the heat treatment temperature and time on changes in the eutectic Si phase morphology (rod shape / granular shape) for water-cooled thin Cu mold castings, particularly die casting. The results showed that the eutectic Si phase may become granulated even at relatively low temperatures (350 to 450℃) in a short time (30 to 120 minutes).