Full annealing Is a type of heat treatment process that can be used for both ferrous and non-ferrous metals. The process consists of the following;
Heating (above the upper critical transformation point)
The steel is heated slowly and uniformly to a temperature approximately 25 deg C above the upper critical transformation point (A3, A1).
Holding (certain period)
The steel is held in the heated state for a certain period of time (varies due to composition). Until the structure is fully austenized and homogenous.
Cooling (Cooled in the furnace)
Once the holding phase has been completed the steel is then cooled at a specific rate within the furnace.
- Coarse (soft) grain pearlitic structure
- Uniform mechanical properties
- Remove internal stresses from the steel
- Improve machinability.
- Recrystalize cold worked steels
- Reduce hardness and toughness
= Removes residual stresses, becomes more softer and adhesive