Annealing, also known as annealing code Th, the steel is heated to AC1 or AC3 (30 to 50 ° C), holding time and then slowly cooled (and general furnace cooling).

Normalizing, also known as fire, Code Z, the steel is heated to above Ac3 or Acm (30 to 50 ° C), holding time, and then cooling in air, the cooling rate is slightly faster than the annealing.

Bearing annealing and normalizing the main difference is: normalizing a metamorphosis or a special case of fully annealed, the two only is the cooling rate, annealing is usually cold and the furnace is normalizing in the air cooling, normalizing applies to both the sub-eutectoid steel is also applicable to common plate steel, eutectoid steel, normalizing generally used to eliminate network carbide; For sub-eutectoid steel, the purpose of normalizing and annealing is basically the same, mainly grain refinement, eliminate the defects in the organization, but normalizing organization pearlite were annealed in fine, and hypoeutectoid the steel pearlescent number of multi-ferrite small number, so, after normalizing the hardness of steel, high intensities were annealed material, can be seen in the production practice, the steel mesh cementite need to after normalizing eliminate, before other processes, and performance requirements of the material after the heat treatment, according to the requirements of the different kinds of steel different choices annealing process, such as: heat treatment is required after a certain strength, hardness, selectable normalizing process; requires a certain plasticity to minimize the strength, hardness should be chosen annealing process.

Bearing production annealing operation types

(1) fully annealed (commonly known as annealing) is mainly used for the sub-total of bridge steel and alloy steel castings, forgings and hot-rolled profiles, and some are also used as a welded structure, which aims to grain refinement to improve the organization, eliminate the residual stress, to reduce hardness, to improve the plasticity, improved cutting performance, fully annealed is a time very long annealing process, in order to shorten its annealing time, is currently often uses, etc. Temperature fire process to replace completely annealing process, compared with the fully annealed, such as temperature.The purpose of the fire is fully annealed, but it is greatly reducing the annealing time.

(2) Ball annealing is mainly used for eutectoid steel and alloy tool steel (such as cutting tools, measuring tools, molds and bearing steels). Its main purpose is to reduce the hardness, improving machinability, and prepare for the future quenching.

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

(4) Recrystallization annealing is used to eliminate the cold (cold drawn and cold, cold, etc.) the work hardening. The purpose is to eliminate stress, improve plasticity, and the organization.

(5) Diffusion annealing is mainly used for alloy steels, particularly alloy castings and ingots. The aim is to use a high temperature has a larger atomic diffusion ability to reduce or eliminate the phenomenon of unevenness of the steel chemical composition.