Non-heat treated crankshaft

Abstract

A non-heat treated crankshaft which comprises, in % by mass, C: 0.30 to 0.35%, Si: 0.40 to 0.80%, Mn: 1.00 to 2.00%, S: 0.040 to 0.080%, Cr: 0.10 to 0.30% and V: 0.05 to 0.20%, with the balance being Fe and impurities, and of which microstructure is a ferrite-pearlite microstructure whose ferrite fraction α is 0.20 to 0.60 and average pearlite grain size Dp is 0.08 mm or less, and the value of Fn1 defined by the equation (1) being 0.73 or more, the value of Fn2 defined by the equation (2) being 1.20 or more and the value of Fn3 defined by the equation (3) being 0.64 or more, having excellent strength, low temperature toughness and wear resistance, so it can be applied to engines for working machine and general-purpose engines: Fn1=C+0.10Si+0.20Mn−0.71S+0.23Cr+1.65V  (1), Fn2=1.4−1.1×(1−α)+0.16 Dp−½  (2), Fn3=(1−α)+α×(0.3Si+0.8V)  (3), where the symbols of the elements in the equations (1) and (3) respect the contents (% by mass) of the elements in the steel.

Dependencies are inferred from the claim text.