Due to the different purposes of precision castings, there are many heat treatments, which can be mainly divided into two categories. The first type is that the structure does not change or should not be changed by heat treatment. The second is that the basic structure changes. The first heat treatment procedure is mainly used to eliminate internal stresses, which are caused by different cooling conditions and conditions during the stainless steel casting process. The structure, strength and other mechanical properties are not significantly changed by heat treatment.
For the second type of heat treatment, Al Qaeda has undergone significant changes, which can be broadly divided into five categories:
1. Softening annealing: Its purpose is mainly to decompose carbides, reduce their hardness and improve processing performance. For spheroidal graphite cast iron, the purpose is to obtain more ferrite structure.
2. Normalizing treatment: The main purpose is to obtain pearlite and sorbite structure to improve the mechanical properties of stainless steel casting.
3, quenching treatment: mainly in order to obtain higher hardness or wear strength, while at the same time to very high surface wear characteristics.
4. Surface hardening treatment: mainly to obtain a surface hardened layer, and at the same time obtain a very high surface wear resistance.
5. Precipitation hardening treatment: Mainly to obtain high strength and the elongation does not change drastically.