Deep Cryogenic Treatment
Deep Cryogenic Treatment is process of treating various material at extremely low temperature (190°C). It is also Called Cryogenic Tempering Or secondary Heat Treatment. This process consist of 3 Stages.
DISCEND
Gradually cooling is material. This slow cooling process from ambient temperature to soaking temperature (190°C) is important in avoiding thermal shocks.
SOAKINNG
Once soaking temperature (190°C) is achieved the cycle shift to soaking stage. This stage consist of holding the soaking temperature for various socking periods depending upon the material.
ASCEND
Soaking Stage Follow by ascend in which material is brought to ambient temperature from soaking temperature.
Deep Cryogenic Treatment is followed by Low Temperature Tempering
Why Deep Cryogenic Treatment
Cryogenic treatment is a supplementary process to conventional heat treatment process in steels. It is an inexpensive, one time permanent treatment affecting the entire cross section of the material unlike coatings.
The purpose of cryogenic treatment is to transform retained austenite into martensite. Austenite (a soft form of iron) is a solid solution of carbon and iron that is formed during the quenching phase of metal production. Austenite is weak and undesirable because it contains few molecular interfaces to help hold the metal together. There may be as much as 30-35% residual austenite in heat-treated ferrous metals. This untransformed austenite is brittle and lacks dimensional stability, which allows the metal to break more easily under loads.