Cryogenic hardening is often referred to cryogenic treatment and cryogenic processing. Using the term "hardening" is not correct. Cryogenic treatment does not increase the hardness of metals (I.E. rockwell hardness).
Rather it changes metals on the molecular level so that they perform better. Cryogenic treatment is used for a variety of reasons including improving dimensional stability, stress relieving, increasing wear resistance, and eliminating walk and creep.
A typical cryogenic treatment lasts for several days. Metal and steel parts will be put in a cryogenic processor at room temperature. The temperature will slowly be taken down to -300F below. Then it will hold there for 12 to 24 hours depending on the company doing the treatment. After that, the processor will have the temperature raised back to room temperature very slowly. Finally, the parts will be post-tempered to finalize the cryogenic treatment.
Cryogenic treatment re-aligns the micro-structure of the metal to improve its structural stability. Retained austenite will be converted to martensite which allows for a tougher piece of metal. The eta-carbides in the metal will become precipitated which allows for a much higher degree of wear resistance.
Below are some good sites for additional reference...
cryogenic metal treatment
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Any gas that liquifies below -150 degrees C is a cryogenic gas. The most popular cryogenic gas is liquid nitrogen.
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Yes
A cryogenic freezer is used to bring components inside the freezer down to cryogenic temperatures. Many cryogenic freezers are available for all sorts of applications. Cold boxes with added ln2 capabilities can refrigerate parts and then complete cryogenic processing cycles. Additionally, cryo freezers are available to freeze sex cells, stems cells, and more. Sometimes people are frozen after death, which is called cryonics. I have added a site below that has cryogenic freezers and processors available.
cryogenic :)
I. Spradley has written: 'Integrated Cryogenic Experiment (ICE) microsphere investigation' -- subject(s): Insulation, Microgravity, Microparticles, Weightlessness, Liquid helium, Cryogenic equipment, Cryogenic storage
mostly is the hardening done by induction hardening machine, I know also manufactures that do this using the flame hardening method.
in my opinion surface hardening is applied only on the surface while the true hardening is applied in the whole part of the metal....
what the was on tooth hardening day?
Arteriosclerosis is hardening of the arteries.