Abstract: A systematic study of the changes in composition and structure of surface layers due to the thermo-chemical and thermo-mechanical affects among the wheel, the workpiece and the grinding fluid during pricision grinding on carburized steel 20CrNi2MoA railway bearing has been conducted. Results show that the grinding affected layers are generated. The grinding affected layers on bearing surface consist of absorption layer, oxide layer, white layer, overtempering and plastic deformation layer. The oxide layer is a mixed structure which consist of Fe and alloy elements oxides, the thickness is not greater than 20nm, the structure of white layer is very fine texture martensite and fine austenite which was elongated in the tangential stress direction. The depth of zone in which the hardness is less than 600HK was not greater than 10μm in the overtemper layer under normally conditions. The thickness of white layer and grinding affected layer incerased as the downfeed was increased.

Key words: Bearing, Carburized steel, Grinding affected layer, Microstructure