STEEL FOR NITROCARBURIZING AND NITROCARBURIZED COMPONENT, AND METHODS FOR PRODUCING SAID STEEL FOR NITROCARBURIZING AND SAID NITROCARBURIZED COMPONENT

摘要

Provided is a steel for nitrocarburizing, of which the composition is so adjusted as to comprise, in mass%, 0.01% or more and less than 0.10% of C, 1.0% or less of Si, 0.5 to 3.0% of Mn, 0.02% or less of P, 0.06% or less of S, 0.3 to 3.0% of Cr, 0.005 to 0.4% of Mo, 0.02 to 0.5% of V, 0.003 to 0.15% of Nb, 0.005 to 0.2% of Al, 0.0005 to 0.02% of Sb and a remainder made up by Fe and incidental impurities, and in which the area ratio of a bainite phase makes up more than 50% of the whole area of the structure of the steel. The steel exhibits excellent machine-processing properties before the nitrocarburization of the steel, exhibits excellent fatigue properties after the nitrocarburization of the steel, and can be used suitably for mechanical structure parts for automobiles and the like.