| 摘要 |
PROBLEM TO BE SOLVED: To provide a rolling shaft capable of suppressing the machining cost with good material formability and little heat deformation bending even in a severe environment of use conditions.SOLUTION: A pinion shaft 5 is made of alloy steel containing by mass: 0.15-0.25% carbon; 2-4% chromium; 0.1-0.6% molybdenum; 0.1-1.5% manganese; and 0.1-1.5% silicon. The pinion shaft 5 is formed of a surface part hardened by carburization or carbonitriding treatment, quenching, and tempering and the surface hardness Hv is 650-900. The residual austenite amount of the surface part is 15-45% by volume. The residual austenite amount of the core inside the surface part is 3% or less by volume. The sum of carbon concentration and nitrogen concentration in the surface layer part is 0.8-2% by mass. |
