Precision casting for the second type of heat treatment and advocate, al qaeda has had the obvious change, can be roughly divided into five categories:1, softening annealing: its purpose is to decompose the carbide, its hardness is reduced, and improve the processing performance, for nodular cast iron, its aim is to gain more ferrite. 2, normalizing treatment: the main purpose is to obtain pearlite and sorbite structure to improve the mechanical properties of the stainless steel casting. 3, quenching, mainly in order to obtain a higher hardness and abrasion strength, at the same time to the surface of the high wear-resisting properties. 4, surface hardening treatment: mainly for surface hardening layer, at the same time, get very high surface wear-resisting properties. 5, precipitation hardening treatment: lost wax casting mainly in order to obtain high strength and elongation is not so violent change.