Abstract
The plasma carburizing process is an innovative surface modification technique for potential application to the vehicle component manufacturing process. In this study, the influence of this relatively new process on the surface hardness of SCM415 low-alloy steel (0.15% C) was investigated under the various process conditions of gas composition, gas pressure, plasma current density, temperature and time. The effective plasma carburizing tem- perature of SCM415 steel was found to be higher than 850°C, and the case depth was proportional to the square root of carburizing time under the same current density. Also, high cycle fatigue and dry wear characteristics of vacuum carburized SCM415 steel were evaluated after various heat treatments. Comparing the fatigue and wear characteristics of vacuum carburized specimens to those of hot annealed or reheat quenched specimens, the wear resistant property as well as bending fatigue limits were found to be substantially improved. The optimum amount of retained austenite exists for the maximum fatigue strength in vacuum carburized steels. Through the quantative analysis of the retained austenite using XRD, this value was found to be about 4%.