Patent ID: 7749432

Claim:
A cast, austenitic steel consisting essentially of, expressed in weight percent of the total composition, about 0.4 to about 0.7 C, about 20 to about 30 Cr, about 20 to about 30 Ni, about 0.5 to about 1 Mn, about 0.6 to about 2 Si, about 0.05 to about 1 Nb, about 0.05 to about 1 W, about 0.05 to about 1.0 Mo, balance Fe, said steel being free of Ti and Co, said steel characterized by at least one microstructural component selected from the group consisting of MC, M 23 C 6 , and M(C, N), wherein total carbides are in the amount of a total weight percent of at least 6 and no more than 9 at a temperature of about 1200° C., and wherein sigma phase formation occurs at a temperature no higher than 680° C.