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A cryogenic treatment is the process of treating workpieces to cryogenic temperatures (i.e. below −190 °C (−310 °F)) in order to remove residual stresses and improve wear resistance on steels. In addition to seeking enhanced stress relief and stabilization, or wear resistance, cryogenic treatment is also sought for its ability to improve corrosion resistance by precipitating micro-fine eta carbides, which can be measured before and after in a part using a quantimet.
The process has a wide range of applications from industrial tooling to the 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.
Cryogenic hardening is a cryogenic treatment process where the material is cooled to very low temperatures. By using liquid nitrogen, the temperature can go as low as −190 °C. It can have a profound effect on the mechanical properties of certain materials, such as steels or tungsten carbide.
Main article: Cryogenic hardening
Applications of cryogenic hardening
Aerospace & Defense: communication, optical housings, weapons platforms, guidance systems, landing systems.
Automotive: brake rotors, transmissions, clutches, brake parts, rods, crank shafts, camshafts axles, bearings, ring and pinion, heads, valve trains, differentials, springs, nuts, bolts, washers.
Cutting tools: cutters, knives, blades, drill bits, end mills, turning or milling inserts. There are two main types of cryogenic treatments of cutting tools: Cryogenic treatments of cutting inserts can be classified as follows: Deep Cryogenic Treatments (DCT) or Shallow Cryogenic Treatments (SCT). A different minimum tool cooling temperature is used in the two mentioned treatments: -196 °C for DCT and -80 °C for SCT.
Forming tools: roll form dies, progressive dies, stamping dies.
Mechanical industry: pumps, motors, nuts, bolts, washers.
Medical: tooling, scalpels.
Motorsports and Fleet Vehicles: See Automotive for brake rotors and other automotive components.
Musical: Vacuum tubes, brass instruments, guitar strings and fret wire, piano wire, amplifiers, magnetic pickups, cables, connectors.
Sports: Firearms, knives, fishing equipment, auto racing, tennis rackets, golf clubs, mountain climbing gear, archery, skiing, aircraft parts, high pressure lines, bicycles, motor cycles.
Cryogenic machining
Cryogenic machining is a machining process where the traditional flood lubro-cooling liquid (an emulsion of oil into water) is replaced by a jet of either liquid nitrogen (LN2) or pre-compressed carbon dioxide (CO2). Cryogenic machining is useful in rough machining operations, in order to increase the tool life. It can also be useful to preserve the integrity and quality of the machined surfaces in finish machining operations. Cryogenic machining tests have been performed by researchers since several decades, but the actual commercial applications are still limited to very few companies. Both cryogenic machining by turning and milling are possible.