| 摘要 |
A high strength steel for dies has excellent machinability and consists essentially of, by weight, 0.005 to 0.1% C, not more than 1.5% Si, not more than 2.0% Mn, from 3.0 to less than 8.0% Cr, not more than 4.0% Ni, 0.1 to 2.0% Al, not more than 3.5% Cu, and balance of Fe and inevitable impurities including N and O, and which has a metal structure whose primary microstructure is martensite, wherein N and O as impurities are restricted to amount ranges of not more than 0.02% N and not more than 0.003% O. In the invention, an improvement in the machinability in heavy cutting and an improvement in the precision electro-spark machining property and high-grade polishing property can be achieved when the above high strength steel has a chemical composition in which the value of (7.7xC(wt%)) + (2.2xSi(wt%)) + (271.2xS(wt%)) is preferably not less than 2.5 and more preferably not more than 6. |
