On the Use of Cyclic Cryogenic Treatment to Improve the Properties of High-Speed Steel.

Cryogenic treatment is a process of controlled gradual cooling of the workpiece to a temperature ranging from -60 °C to even below -190 °C, holding the workpiece at this temperature and then slowly reheating it to ambient temperature. According to the current state of knowledge, the purpose of cryogenic treatment is to reduce the concentration of retained austenite by transforming it into hard martensite under low-temperature treatment. The retained austenite reduction in steels results in improved hardness, impact strength, and wear resistance. This study involved conducting comparative tests of the hardness, tensile strength, and impact strength of high-speed steel samples with and without cryogenic treatment, which made it possible to determine the effect of cyclic cryogenic treatment on the properties of this steel. In addition to that, machining tests were conducted to assess the life of a cutting tool edge made from both cryogenic-treated and non-cryogenic-treated high-speed steel. Also, the austenite concentration in the samples was measured by X-ray diffraction. Obtained results confirmed that the cyclic cryogenic treatment enhanced all tested properties of the high-speed steel.