| 摘要 |
<p>Provided is a martensite steel which can be imparted with ductility while maintaining excellent strength properties thereof, i.e., a martensite steel which can have both strength and ductility. A martensite steel having a chemical composition containing, in mass%, 0.18 to 0.30% of C, and 1.0 to 2% of Al and 0.3% or less of V, 2.0 to 5.0% of Cr, 10.5 to 15.0% of Ni wherein Ni≥7.0+3.5Al, also containing 5.0 to 7.0% of Co, 1.0 to 4.0% of Mo alone or Mo+W/2, selected elements B, Si, Mn, Ca, a rare earth element, Cu and Nb wherein B is contained in an amount of 0.0050% or less, Si is contained in an amount of 0.4% or less, Mn is contained in an amount of 0.4% or less, Ca is contained in an amount of 0.05% or less, the rare earth element is contained in an amount of 0.05% or less, Cu is contained in an amount of 1.0% or less and Nb is contained in an amount of 0.1% or less, with the remainder made up by Fe and impurities. The martensite steel additionally contains Mg in an amount of 40 ppm or less (excluding 0%).</p> |
