Effect of Roller Burnishing on the Plasma Nitriding of Tool Steel SKD61

Abstract

The drawback of most traditional plasma nitriding processes is that they require a longer treatment time to form a deep nitrided layer. Hence, the study of hybrid treatment with added plasma nitriding was recently reported to decrease treatment time. However, conventional hybrid treated samples have lost their mirror surface because of increasing surface roughness. A hybrid treatment that maintains surface roughness is also required. Therefore, roller burnishing was performed before plasma nitriding of tool steel using Electron-Beam-Excited Plasma. In this study, the effects of the roller burnishing on the formation of nitrided layers were investigated. The results show that the roller burnished samples had lower surface roughness than untreated samples. Roller burnished and then plasma nitrided samples had a mirror surface. The depth of the nitrided layer of roller burnished samples was increased from 20 to 30μm compared to untreated samples. The burnishing also suppresses the formation of the compound layer depending the conditions.