Deep cryogenic treatment (DCT) is a type of cryogenic treatment, where a metallic material is subjected to temperatures below -150°C, normally to temperatures of liquid nitrogen (-196 °C). When a material is exposed to DCT as a part of heat treatment, changes in microstructure are induced due to new grain formation, changes in grain size, change in the solubility of atoms, movement of dislocations, alteration of crystal structure, and finally new phase formation. The metallic material's performance and later performance of manufactured components and tools from this specific material are dependent on the selection of proper design, proper material, accuracy with which the tool is made and application of proper heat treatment, including any eventual DCT. Metallic materials are ferrous and non-ferrous metals. In the last years ferrous metals (different grades of steel) and non-ferrous alloys (aluminum, magnesium, titanium, nickel etc.) have been increasingly treated with DCT to alter their properties. DCT treatment has shown to reduce density of defects in crystal structure, increase wear resistance of material, increase hardness, improve toughness, and reduce tensile strength and corrosion resistance. However, some researchers also reported results showing no change in properties (toughness, hardness, corrosion resistance, etc.) or even deterioration when subjected to DCT treatment. This leads to a lack of consistency and reliability of the treatment process, which is needed for successful application in industry. This review provides a synopsis of DCT usage and resulting effects on treated materials used in automotive industry.
Deep Cryogenic Treatment of Metallic Materials
