(1) Complete annealing (commonly known as annealing) is mainly used for castings, forgings and hot rolled sections of sub common bridge steel and alloy steel, and some are also used as welded structural parts. Its purpose is to refine grains, improve microstructure, eliminate residual stress, reduce hardness, improve plasticity and improve machinability. Complete annealing is an annealing process with a long time. In order to shorten its annealing time, At present, isothermal fire process is often used to replace complete annealing process. Compared with complete annealing, the purpose of isothermal fire is the same as complete annealing, but it greatly shortens the annealing time.

(2) Spheroidizing annealing is mainly used for hypereutectoid steel and alloy tool steel (such as all kinds of steel such as cutting tools, measuring tools, molds and bearings). Its main purpose is to reduce hardness, improve machinability and prepare for future quenching.

(3) Stress relief annealing (also known as low temperature annealing) is mainly used to eliminate the internal stress of castings, forgings, weldments and hot rolled parts.

(4) Recrystallization annealing is used to eliminate work hardening caused by cold working (cold drawing, cold stamping, cold rolling, etc.). The purpose is to eliminate internal stress, improve plasticity and improve microstructure.

(5) Diffusion annealing is mainly used for alloy steel, especially alloy steel castings and ingots. The purpose is to reduce or eliminate the non-uniformity of chemical composition in steel by using the large diffusion ability of atoms at high temperature。