Heat resistant nickel chromium steel - is sigma phase-free and has reduced nickel content

摘要

A heat resistant, cast alloy steel has the compsn. (by wt.) 0.2-0.5% C, 18-28% Ni, 14-18% Cr, 1-2.5% Si, 0.1-2% Mn, 0-6 times the C content of Nb, 0-0.1% Ce, balance Fe and impurities, with the proviso that X is less than or equal to 0 (pref. equal to -1) where X is (4.5a + 11b) - (1.1c + 58d + 61), a being the % Cr, b being the % Si, c being the % Ni and d being the % C in the steel. The steel has reduced cost because of its relatively low Ni content compared with conventional heat resistant steels used in heat treatment furnaces, petrochemical works, cement works, etc. Sigma phase formation during prolonged heating at 650 deg.C, as indicated by the value of X, is prevented.