The Big Chill

This article reviews the improvement of wear resistance of steel that can amount to found money, particularly in industrial uses such as stamping dies and machine tools. Quenching converts most of the austenitic microstructure to the martensitic phase, which is finer and denser. Martensite, the chief component of quenched steel, consists of hardened carbides that provide the higher hardness and wear resistance. Cryogenics has attracted the interest of others who want to improve wear resistance in wider applications. As a follow-on treatment to conventional heat treating, cryogenics should be seen as the very last step in the process. After wear tests, in which cryogenically treated parts were run against an abrasion wheel, it was found that weight loss on several steel grades improved by factors of two to five. It was also found that the overall hardness of the treated steel did not change noticeably.