Cryogenic Treatment of Tool Materials: A Review

Cryogenic treatment is a thermal treatment process in which parts are usually cooled to temperatures below −70 °C (< 203 K) to induce metallurgical changes in materials. The treatment showed a significant performance improvement in most ferrous materials and their alloys by transforming retained austenite to martensite and precipitating secondary carbides. However, the effect of such low-temperature treatment on highly stable super-hard materials such as tungsten carbide (commonly referred to as “cemented carbide”) is uncertain. However, researchers have reported the precipitation of etaphase carbides, densification of cobalt binder, refinement of tungsten carbide grains, phase transformation of cobalt, and changes in residual stress in cryogenically treated tungsten carbide (WC-Co) materials, which resulted in increased hardness and wear resistance. Hence, this paper focuses on summarizing the cryogenic treatment parameters used in different studies, the rate of performance improvement in different applications, and the reported mechanical and metallurgical changes, which would serve as a pool of knowledge for further studies.