Experimental Study on the Reheating Process for A356 Alloy in Thixoforming

The induction heating of the billets is a critical step in the thixoforming process. To improve the quality of thixoforming, the induction heating strategy should be investigated. In this study, by using an induction heating system of 50 kHz, multi-step reheating schemes were adopted to reheat the nondendritic A356 alloy to the temperature between the solidus and liquidus line. To obtain uniform temperature distribution and fine globular microstructure, the effects of the reheating parameters, such as reheating time, reheating temperature, holding time and holding temperature, were investigated. Then the analysis of the final temperature difference and the optical microstructure of the reheated billets were conducted, the results showed that two-step reheating process is suitable for A356 alloy with the size of phi 45 mm x 25 mm, and the suitable time for the final holding process is 2 min.