Optimization of Cryogenic Treatment on Wear Behaviour of D6 Tool Steel by Using DOE/RSM

In this work, the effects of cryogenic treatment on the wear behavior of D6 tool steel were studied. For this purpose, two temperatures were used: -63 o C as shallow cryogenic temperature and -185 o C as deep cryogenic temperature. The effects of cryogenic temperature (Shallow and deep), cryogenic time (kept at cryogenic temperature for 20 and 40 h) on the wear behavior of D6 tool steel were studied. Wear tests were performed using a pin-on-disk wear tester to which different loads and different velocities 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. The combination of heat treatment would have to be optimised. For that purpose Design of Experiment (DOE) is performed. The DOE is done with help of statistical tool i.e. minitab 16. Produced optimum runs with help of Response surface methodology (RSM) by Box-Behnken design.