GAS-CARBURIZED STEEL COMPONENT WITH EXCELLENT SURFACE FATIGUE STRENGTH, GAS-CARBURIZING STEEL MATERIAL, AND PROCESS FOR PRODUCING GAS-CARBURIZED STEEL COMPONENT

摘要

A gas-carburizing steel material which is to be used in producing a carburized steel component, wherein the base metal has a composition that contains, by mass, 0.1 to 0.4% of C, more than 1.2 to 4.0% of Si, 0.2 to 3.0% of Mn, 0.5 to 5.0% of Cr, 0.005 to 0.1% of Al, 0.001 to 0.3% of S, and 0.003 to 0.03% of N, with the contents of O and P being limited to at most 0.0050% and at most 0.025% respectively, and that satisfies relationship (1) [wherein [Si%], [Mn%] and [Cr%] represent the contents (in mass%) of Si, Mn and Cr respectively], and an alloy-deficient layer satisfying relationship (2) is present within the region from the surface to a depth of 2 to 50μm.32 ≥ 3.5[Si%] + [Mn%] + 3[Cr%] 9 ··· (1)3.5[Si%] + [Mn%] + 3[Cr%] ≤ 9 ··· (2)