| 摘要 |
<p>A low-carbon resulfurized free-cutting steel material which contains less than 0.05% C, less than 0.05% Si, 0.7-2.2% Mn, 0.03-0.20% P, 0.40-0.70%, excluding 0.40% and 0.70%, S, less than 0.005% Al, 0.0050-0.0380% O, and 0.0020-0.0250% N, with the remainder being iron and impurities, wherein Ca, Mg, Ti, Zr, and REM among the impurities satisfy the following relationships: Ca<0.001%, Mg<0.001%, Ti<0.002%, Zr<0.002%, and REM<0.001%, provided that 0.010<O/S<0.080 and 2.5<Mn/(S+O)<4.0. When cut with a high-speed steel tool, the steel material has the same chip disposability as conventional Pb-free free-cutting steel materials and has better finished-surface properties than those. It is excellent also in continuous castability and hence suitable for mass production. This material may contain at least one of Te<=0.05%, Bi<=0.15%, and Se<0.30%.</p> |
