Sometimes known as Sub-Zero Treatment. This involves freezing components down to temperatures as low as -196°C. There can be a variety of reasons to carry out this treatment as below:-
- As part of the tempering process, to ensure that full transformation to an ideal microstructure has occurred.
- In carbide tools studies have been performed where freezing the tools “tightens” up the matrix giving improved properties dependant on application.
- For components that will be experiencing low temperatures in service where it is important that any size change happens before the part enters service.
- To increase the abrasive wear resistance of certain tool steels, high-speed steel cutting tools have been shown to have increased wear in use after deep freezing.
- Autosport applications where it has been suggested that part life is increased due to deep freezing.
- The process is also used to aid shrink fitting of components when heating of the outer component is restricted.
Cryogenic treatment is commonly specified as part of the heat treatment process cycle for critical components in aerospace, medical, motorsport and other highly stressed applications.