Full annealing

A synonym for annealing.

It is used to avoid confusion with the many other types of annealing such as recrystallisation annealing, process annealing, etc.

Full annealing consists of heating steel to above the upper critical temperature, and slow cooling, usually in the furnace. It is generally only necessary to apply full annealing cycles to the higher alloy or higher carbon steels. In some instances a special form of full annealing called isothermal annealing is used, to obtain maximum softening response. This consists of holding the steel at a selected temperature above the upper critical temperature for sufficient time to allow transformation to pearlite before cooling the steel. Long cycle times are required to do this with many high alloy steels and it is therefore expensive.

Where it is considered desirable to fully austenitise a steel during a softening process, (e.g. to refine forged structures etc.) but economy is important, a normalising treatment is often used rather than a time consuming full anneal. This consists of heating above the upper critical temperature and air cooling. This process is only applicable to plain carbon and low alloy steels.

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