The heat treatment of aluminum alloy castings can be divided into artificial aging (T1), annealing (T2), solid solution treatment (T4), solid solution treatment + incomplete artificial aging (T5), solid solution treatment + complete artificial aging (T6), solid solution treatment + stabilization tempering (T7), solid solution treatment + softening tempering (T8), etc. The process of each heat treatment is different. The die casting produced by the conventional process can be treated as T1 and T2. Still, it cannot be treated as a solid solution, because the gas in the casting will expand and form bubbles, resulting in the abandonment of the casting when the die casting is heated to the temperature of the solid solution. However, the die castings produced by special processes (such as high vacuum, semi-solid, extrusion, etc.) can still be treated with T4, T5, T6, T7, and T8 because there are no or few internal pores.