To provide a soft-nitrided stock for a crankshaft, maintaining excellent strength and further having excellent bending straightening properties upon bending straightening following soft nitriding treatment.
The soft-nitrided stock for a crankshaft has a composition comprising, by mass, 0.35 to 0.55% C, 0.05 to 0.5% Si, 0.6 to 1.2% Mn, 0.01 to 0.5% Cu, 0.01 to 0.5% Ni, 0.05 to 0.6% Cr, 0.01 to 0.40% V, 0.04 to 0.1% S, 0.001 to 0.01% s-Al, 0.0005 to 0.02% Ca and 0.001 to 0.04% N, and the balance Fe with inevitable impurities, and further has a structure of ferrite+pearlite in which the respective components are regulated in such a manner that, when the content of V capable of being solid-soluted into γ upon normalizing heating is defined as [V] and a carbon equivalent is defined as C[eq.], the following relationship, C[eq.]=C+0.07Si+0.16Mn+0.19Cu+0.17Ni+0.2Cr+[V], satisfies 0.58 to 0.89%.
COPYRIGHT: (C)2007,JPO&INPIT
SUWA SATORU
MURAKAMI ATSUSHI
HONDA MOTOR CO LTD
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