| 摘要 |
PROBLEM TO BE SOLVED: To provide a steel member which is used as steel parts for machine structures combining excellent pitting resistance and fatigue strength, tools having excellent wear resistance or the like. SOLUTION: The core part of the steel member has chemical components containing, by mass, 0.10 to 0.30% C, 0.15 to 1.0% Si, 0.20 to 1.0% Mn, 1.0 to 2.0% Cr and 0.05 to 0.6% Mo, are containing one or more elements selected from the group consisting of 0.005 to 0.05% Al, 0.005 to 0.05% Nb and 0.005 to 0.1% Ti, and 0.008 to 0.05% N. Further, the austenitic crystal grain size number after carburizing, quenching and tempering is >=8.5. The surface density of carbides having a diameter of <=0.5μm in the surface layer part within 50μm from the surface is >=6.0 pieces/10μm2. The ratio of the number of the carbides with a diameter of <=0.5μm occupied in the total number of carbides is >=80%.
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