Due to the different purposes of precision castings, there are many heat treatments, which can be basically divided into two categories. The first type is that the structure will not change or should not change through heat treatment, and the second is that the basic structure changes. The first heat treatment procedure is mainly used to eliminate internal stress, which is caused by different cooling conditions and conditions during the stainless steel casting process. The structure, strength and other mechanical properties will not change significantly due to heat treatment.
For the second type of heat treatment, al Qaeda has undergone significant changes, which can be roughly divided into five categories:
- Softening annealing: Its purpose is mainly to decompose carbide, reduce its hardness, and improve processing performance. For ductile iron, its purpose is to obtain more ferrite structure.
- Normalizing treatment: The main purpose is to obtain pearlite and sorbite structure to improve the mechanical properties of stainless steel casting.
- quenching treatment: mainly to obtain higher hardness or abrasion strength, and at the same time to very high surface wear resistance.
- Surface hardening treatment: mainly to obtain a surface hardened layer, while obtaining a very high surface wear resistance.
- Precipitation hardening treatment: Mainly to obtain high strength without drastic changes in elongation.