Case hardening development review (2001-2020)

The purpose of the work is a complex review of methods applied industrially as case hardening. The paper contains an overview of scientific and development works on surface case hardening methods, especially carburising and quenching, described in the literature from 2001-2020.State-of-the-art was reviewed by a critical review of the world literature published in 2001-2022, including theoretical work, scientific research, and industry reports. An additional examination of the state of the art was conducted in terms of patent works.The period of 2001-2020 was a time of intensive work on the modernisation of case hardening techniques to improve the repeatability and uniformity of the produced layers and minimise deformations after hardening. Developing computing technologies have played a large part in this progress. New technologies have also been developed.The review of papers and patent databases was limited to databases providing English-language content options.Case hardening is a crucial stage of steel heat treatment in almost every industrial branch: mechanical, tool, automotive, railway, and aviation.A synthetic review of case hardening methods was presented, particularly carburizing and quenching methods; it also analysed the possibilities and directions of their development.