STEEL COMPONENT FOR MECHANICAL STRUCTURAL USE AND MANUFACTURING METHOD FOR SAME

摘要

Provided is a steel component for mechanical structural use having increased fatigue resistance and toughness without any reduction in machinability; also provided is a manufacturing method for the same. A steel component: is formed from steel which includes, in mass%, 0.05-0.20% C, 0.10-1.00% Si, 0.75-3.00% Mn, 0.001-0.050% P, 0.001-0.200% S, more than 0.20-0.25% V, 0.01-1.00% Cr, 0.001-0.500% Al, and 0.0080-0.0200% N, with the remainder being Fe and unavoidable impurities. The steel structure is at least 95% bainite structure, in terms of area ratio; the width of the bainitic lath is not more than 5µm; V carbide having an average particle diameter of 4-7nm is dispersed and is present in the bainite structure; and the area ratio of the V carbide in the bainite structure is at least 0.18%.