| 摘要 |
PROBLEM TO BE SOLVED: To provide a high-strength shaft which has adequate impact-bending resistance, and besides, adequate abrasion resistance and seizure resistance, and to provide a manufacturing method therefor. SOLUTION: This manufacturing method includes the steps of: preparing a steel material composed of, by mass ratio, 0.15% to 0.60% C, 0.2% or less Si, 0.10% to 0.70% Mn, 0.03% or less P, 0.03% or less S, 0.1% to 1.6% Cr, 0.6% to 1.5% Mo, 0.05% to 0.40% V and the balance Fe with unavoidable impurities; quenching the steel material at 880°C or higher; and subjecting it to nitrocarburizing treatment in a salt-bath or nitrocarburizing treatment by gas at 550 to 650°C. Thus obtained shaft has an internal hardness of 400 Hv or more and a hardness of 600 Hv or more at the position of 0.05 mm deep from its surface; and has a nitride layer with a thickness of 25μm or less formed on the surface. COPYRIGHT: (C)2009,JPO&INPIT
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