Effects of cryogenic treatment on wear behavior of D6 tool steel

In this paper, the effects of cryogenic treatment on the wear behavior of D6 tool steel were studied. For this purpose, two temperatures were used: −63 °C as shallow cryogenic temperature and −185 °C as deep cryogenic temperature. The effects of cryogenic temperature (Shallow and deep), cryogenic time (kept at cryogenic temperature for 20 and 40 h) and stabilization (kept at room temperature for 1 week) on the wear behavior of D6 tool steel were studied. Wear tests were performed using a pin-on-disk wear tester to which two different loads(120 and 180 N) and three different velocities (0.05, 0.1 and 0.2 m/s) were applied. The findings showed that the cryogenic treatment decreases the retained austenite and hence improves the wear resistance and hardness. Due to more homogenized carbide distribution as well as the elimination of the retained austenite, the deep cryogenic treatment demonstrated more improvement in wear resistance and hardness compared with the shallow cryogenic treatment. By increasing the keeping time at cryogenic temperatures, more retained austenite was transformed into martensite; thus, the wear resistance was improved and further hardness were observed. By keeping the samples for a period of 1 week at room temperature after quenching (stabilization), more retained austenite was transformed into martensite and higher wear resistance and higher hardness were achieved.