PRECIPITATION-HARDENED STAINLESS STEEL AND PROCESS FOR PRODUCTION THEREOF

摘要

Disclosed is a high-strength stainless steel which keeps the tensile strength and ductility at such levels that can be achieved by conventional high-strength stainless steels and which has improved 0.2% strength. Specifically disclosed is a precipitation-hardened stainless steel which comprises, in mass%, 0.2% or less of C, 7 to 14% inclusive of Ni, 0 to 3.5% inclusive of Co, 9.5 to 14% inclusive of Cr, 0.5 to 3% inclusive of Mo, 0.25 to 1% exclusive of Al, more than 0.75% and not more than 2.5% of Ti, and a reminder made up by Fe and impurities, and which meets all of the requirements represented by formulae (1) to (4). Formula (1): 1260-65Ni-20Co-40Cr = 0 Formula (2): 670+75Ni+40Co-100Cr = 0 Formula (3): 0.125 = (Al/Ti) = 1.25 Formula (4): 1.45 = (Al+Ti) = 2.95 In the formulae, the contents of Ni, Co, Cr, Al and Ti are calculated in mass%.