CARBURIZED COMPONENT AND MANUFACTURING METHOD THEREFOR

摘要

Provided is a carburized component having excellent fatigue strength in the "low-to-mid-cycle regime." Said carburized component comprises a steel having a chemical composition as follows: the base steel contains 0.15-0.25% carbon, 0.03-0.50% silicon, more than 0.60% and up to 1.5% manganese, no more than 0.015% phosphorus, 0.006-0.030% sulfur, 0.05-2.0% chromium, no more than 0.10% aluminum, no more than 0.03% nitrogen, and no more than 0.0020% oxygen; the steel also contains specific amounts of molybdenum, copper, nickel, boron, titanium, niobium, and/or vanadium as necessary; and the remainder comprises iron and impurities. The surface hardened layer of the carburized component fulfills the following conditions: (a) the mean carbon concentration up to a depth of 0.2 mm from the outermost surface is between 0.35% and 0.60%; (b) the surface roughness Rz is at most 15 µm; and (c) the compressive residual stress at the outermost surface of the component is no more than -800 MPa, the compressive residual stress 100 µm from the outermost surface of the component is no more than -800 MPa, and Ir is at least 80,000, where Ir is the integral of sr(y) dy from 0 to 100, y being the depth in µm from the outermost surface of the component up to a depth of 100 µm and sr(y) being the residual stress at a depth y.