The induction heating process of semi-solid aluminium alloys for thixoforming and their microstructure evaluation

The optimal inductive coil design in the induction heating process of A356 (ALTHIX) alloy billets of 76 mm diameter and 90 mm length to reduce the temperature gradient of the billet and to obtain a globular microstructure was theoretically proposed and tested by reheating experiments. The optimal reheating conditions to apply the thixoforming process were investigated by changing the reheating time, holding time, holding temperatures, capacity of the induction heating system, and adiabatic material size. This study shows that, the larger the billet size, the better the multi-step reheating, and the heating time and the capacity of the induction heating system must be increased. In case of the three-step reheating process, the final holding time is most important factor and 2 min is suitable to maintain a globular microstructure.