| 摘要 |
A case hardening steel material which has a chemical composition that contains, in mass%, 0.15 to 0.23% of C, 0.01 to 0.15% of Si, 0.65 to 0.90% of Mn, 0.010 to 0.030% of S, 1.65 to 1.80% of Cr, 0.015 to 0.060% of Al, 0.0100 to 0.0250% of N, and if necessary, a specific amount of Cu and/or Ni with the balance being Fe and impurities and that satisfies 25 ≤ Mn/S ≤ 85, 0.90 ≤ Cr/(Si+2Mn) ≤ 1.20, and 1.16Si+0.70Mn+Cr ≥ 2.20 with the contents of P, Ti and O as impurities satisfying P≤0.020%, Ti≤0.005% and O≤0.0015% and which has a structure that comprises 20 to 70% of ferrite in area fraction with the remainder being pearlite and/or bainite. This case hardening steel material exhibits a low component cost and excellent hot workability and machinability, and can ensure excellent bending fatigue strength and wear resistance of a carburized part, thus being suitable as a raw material for a carburized part such as a CVT pulley shaft. |
