Effects of rheocasting and heat treatment on microstructure and mechanical properties of A356 alloy

▶ The temperature range for solid–liquid region in A356 alloy is between 560°C and 630°C. ▶ The solid fraction increases from 0% to 100% with decreasing temperature. ▶ Pressures can break down the secondary dendrite arms result in grain refinement. ▶ Mechanical properties of rheocasting specimens have been improved. The effects of the rheocasting process and T5 heat treatment on microstructure and mechanical properties of A356 alloy were investigated. The results show that the temperature range for the solid–liquid state is roughly between 560°C and 630°C, and the solid fraction increases from 0% to 100% with decreasing temperature. The finer microstructure in rheocasting in comparison with the one in conventional casting was attributed to pressure breaking down the secondary dendrite arms, especially for specimens around 600–610°C. It was proved that rheocasting specimens have improved mechanical properties over the conventional casting ones. Furthermore, the result shows that T5 heat treatment can strengthen A356 alloy, while the plasticity was reduced at the same time.