Forged product with a steel composition containing 0.15-0.75C, Si, Mn, Ni, Cr, Mo, V and Al and crankshaft manufactured from it

摘要

When the density (D o ) of the inclusions whose major axis exceeds 5 µm observed in the axis position of a section perpendicular to the axial direction of a forged product is made 70 nos/cm 2 or below and the radius of the forged product is made R, the ratio of the density (D R ) of the inclusions whose major axis exceeds 5 µm observed in the R/3 position from the axis position toward the radial direction and the density Do satisfies an inequality (1) below. 0.5 ‰¤ D R / D O ‰¤ 1.50