PRECIPITATION-HARDENED MARTENSITIC CAST STAINLESS STEEL HAVING EXCELLENT MACHINABILITY, AND METHOD FOR PRODUCTION THEREOF

摘要

Disclosed is a precipitation-hardened martensitic cast stainless steel which comprises the following components (by mass): 0.08-0.18% of C; 1.5% or less of Si; 2.0% or less of Mn; 0.005-0.4% of S; 13.5-16.5% of Cr; 3.0-5.5% of Ni; 0.5-2.8% of Cu; 1.0-2.0% of Nb; and 0.12% or less of N, provided that the total content of C, N and Nb meets the requirement represented by the following formula: -0.2 = 9(C%+0.86N%) - Nb% = 1.0, with the remainder being Fe and unavoidable impurities, and which has a structure formed by a base material mainly composed of tempered martensite and a Cu precipitate having an average particle diameter of 0.1-0.4 µm dispersed in the base material.