Cryogenic treatment: Difference between revisions
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It has been found and proved that cryogenic treatment improves wear resistance of many alloy steels to a great extent. |
It has been found and proved that cryogenic treatment improves wear resistance of many alloy steels to a great extent. |
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==See also== |
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*[[Cryogenic hardening]] |
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==References== |
==References== |
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Revision as of 00:38, 2 October 2009
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A cryogenic treatment is the process of reducing the temperature of components over an extended period of time to extreme cold levels, usually slightly below −190 °C (−310.0 °F), which is why it is called a cryogenic process. Liquid nitrogen (LN2) is a common fluid for the process being relatively inexpensive and making up more than 70% of our atmosphere.
As the LN2 boils off from liquid to gas at around −195 °C (−319.0 °F), the components in its proximity are also cooled. The process is controlled by microprocessors so that thermal shock is not generated at the same time resulting in damage to components. Before these microprocessors were created, people would dip parts in liquid nitrogen and virtually turn them to brittle instantaneously.
As the material cools its molecular structure is drawn together through contraction and stress and dislocation brought about by production methods is removed or reduced. Both Einstein and Bose of Germany realized why cryogenic treatment was able to remove residual stresses. Cryogenic treatment removes heat from an object which then allows the object to enter its most relaxed state or a condition with the least amount of kinetic energy. After heat treatment, steels still have a certain percentage of retained austenite which can be transformed into martensite via cryogenic treatment. Other effects are the production of martensite and the precipitation of Eta type carbides. All metals including copper and aluminum, not just steel benefit from the residual stress relief that cryogenic treatment promotes.[1]
The process has a wide range of applications from industrial tooling to improvement of musical signal transmission. Some of the benefits of cryogenic treatment include longer part life, less failure due to cracking, improved thermal properties, better electrical properties including less electrical resistance, reduced coefficient of friction, less creep and walk, improved flatness, and easier machining.
It has been found and proved that cryogenic treatment improves wear resistance of many alloy steels to a great extent.