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The effects of the carburizing process on the sliding wear behavior of SCM420H steel have been investigated. In particular, the effects of grain boundary corrosion observed in the surface layer after gas carburizing and the effects of hardness of the carburized cases after heat-treatment on the sliding wear properties were examined. Pin specimens carburized by two methods (gas carburizing and vacuum carburizing) were tempered at two temperatures of 180℃ and 400℃ after oil-quenching, respectively. Sliding wear tests were carried out against heattreated SKH51 steel at several sliding speeds using a pin-on-disc type test machine. As results, it can be found that there is no difference in the wear behavior between the pins carburized using two methods. This implies that the grain boundary corrosion that formed in the surface layer after gas carburizing has no effect on the sliding wear behavior of carburized SCM420H steels. Additionally, there is no significant difference in the wear behavior between carburized pins tempered at 400℃ and at 180℃ after oil-quenching, regardless of the carburizing method. This is because carburized pins tempered at 400℃ have a troostite structure, which exhibits higher tribochemical reactivity even though its hardness is lower than that of martensite structure. In this respect, it can be considered that good wear resistance of carburized cases is maintained at least until the effective case depth.