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

The present invention is based on the weight percentage of 0.30 to 1.0 C, 0.4 to 1.3 Si, 0.3 to 1.0 Mn, P≤0.03 , 0.010 to 0.055 S, 0.01 to 0.10 Of Al, from 0.0003 to 0.006 B, from 0.002 to 0.010 N and 0.05 at 0.20 Of Mo and Fe and inevitable impurities, 4.0 0.3 to 1.0 with an average particle diameter of less than or equal to at least 3,000pcs / mm ² This of the cold workability, excellent fine graphite ability cutting performance and the curing containing the graphite steel having a uniformly distributed steel and the composition of the cooling start temperature outside the point Ar _1, a cooling finish temperature below the M _s point, the average cooling rate It provides a manufacturing method consisting of cooling to 5 to 100 ℃ / s.