| 摘要 |
PROBLEM TO BE SOLVED: To provide a non-heattreated crankshaft which has excellent strength, wear resistance and toughness. SOLUTION: The non-heattreated crankshaft comprises 0.30 to 0.35% C, 0.40 to 0.80% Si, 1.00 to 2.00% Mn, 0.040 to 0.080% S, 0.10 to 0.30% Cr and 0.05 to 0.20% V, with the balance being Fe and impurities, and of which structure is a ferrite-pearlite structure whose ferrite fractionαis 0.20 to 0.60 and average pearlite grain size Dp is 0.08 mm or less. Also, the value of Fn1 defined by the following equation being 0.73 or more, the value of Fn2 is 1.20 or more, and the value of Fn3 is 0.64 or more: the equations are shown by (Fn1=C+0.10Si+0.20Mn-0.71S+0.23Cr+1.65V), äFn2=1.4-1.1(1-α)+0.16Dp<SP>-1/2</SP>}, and äFn3=(1-α)+α(0.3Si+0.8V)}, where the symbols of the elements in the equations respect the contents (%by mass) of the elements in the steel. COPYRIGHT: (C)2004,JPO
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