Quenching steel causes the austenite to transform into martensite, however, the transformation is rarely 100% complete.
Some austenite crystals will remain unchanged even after quenching. Further transformation of the austenite into martensite can be induced by slowly cooling the metal to extremely low temperatures. Typical cryogenic treatments are performed between -110 oF and -300 oF.
Cryogenic treatment services are typically performed immediately after quenching, before any tempering, and will increase the hardness and wear resistance. The process is often used for tools, bearings, case hardened parts or other items that require increased hardness and good wear resistance.
One additional benefit of the cryogenic treatment is improved dimensional stability of the parts. When metals are heat treated some dimensional changes can occur. This is due to several factors, including stresses in the material and the incomplete transformation of austenite to martensite. The application of the cryogenic treatment can help reduce the degree of dimensional changes that occur during the heat treating process.
Typical applications of Crygenic Treatment Services – Case hardened parts, some tool steels