Patent attributes
To provide a forged crankshaft having an excellent wear resistance. The forged crankshaft according to the present embodiment includes a non-heat treated steel material. The non-heat treated steel material has a chemical composition which contains, by mass %, C: 0.45 to 0.70%, Si: 0.75 to 1.30%, Mn: 1.00 to 2.00%, S: 0.03 to 0.30%, Cr: 0.05 to 0.30%, Al: 0.005 to 0.050%, and N: 0.005 to 0.020%, the balance being Fe and impurities, and satisfies the following Formula (1):1.1C+Mn+0.2Cr>2.0 (1)where a symbol of each element in Formula (1) is substituted by the content (mass %) of the each element. A matrix of the non-heat treated steel material is a ferrite-pearlite microstructure in which an area ratio of pro-eutectoid ferrite is less than 10% or a pearlite microstructure.
