The heat treatment of aluminum alloy castings can be divided into artificial aging (T 1), annealing (T2), solution treatment (T4), solution treatment+incomplete artificial aging (T5), solution treatment+complete artificial aging (T6), solution treatment+stabilized tempering (T7), solution treatment+softened tempering (T8) and so on. Each heat treatment. Die castings produced by conventional technology can be treated with T 1 and T2, but they cannot be treated with solid solution, because the gas in the castings heated to solid solution temperature will expand to form bubbles, which will lead to the rejection of the castings. However, die castings produced by special processes (such as high vacuum, semi-solid, extrusion, etc.). ) Heat treatment can still be carried out through T4, T5, T6, T7 and T8, because there are no or few pores inside.