| 摘要 |
<p>A steel material containing fine graphite particles uniformly dispersed therein and having excellent cold workability, machinability and hardenability and obtained by especially dispersing five graphite particles uniformly therein. The steel contains basic components comprising 0.30-1.0 % of C, 0.4-1.3 % of Si, 0.3-1.0 % of Mn, 0.003-0.006 % of B, 0.002-0.010 % of N and 0.05-0.20 % of Mo, and the graphite has an average grain size of not more than 4.0νm, and the number of grains of not less than 3000/mm2, and the manufacturing method comprises cooling the steel with a cooling starting temperature of not lower than the Ar¿1? point and a cooling finishing temperature of not higher than the Ms point and at an average cooling rate of 5-100 °C/s.</p> |
