STEEL MATERIAL CONTAINING FINE GRAPHITE PARTICLES UNIFORMLY DISPERSED THEREIN AND HAVING EXCELLENT COLD WORKABILITY, MACHINABILITY AND HARDENABILITY, AND METHOD OF MANUFACTURING THE SAME

摘要

With excellent cold working, machinability and harden ability, the steel containing the fine graphite particle being distributed in wherein even dispersion, it is by especially by the distribution of graphite particle even dispersion prepared by wherein. It includes C0. that the steel, which contains main component,30-1.0%, Si0.4-1.3%, Mn0.3-1.0%, B0.003-0.006%, N0.002-0.010 and Mo0.05-0.20%, and the average particle size particle size of graphite is not more than 4.0 μm, the number of particle is no less than 3000/mm2, and manufacturing method includes to cool down start temperature not less than Ar1 points, and the cooling temperature that terminates is not higher than Ms points, the average cooling this steel of 5-100 DEG C of cooling rate/S.