Patent ID: 8431072

Claim:
An austenitic iron base alloy consisting essentially of, in weight percent ranges: 0.15-0.5C; 8-37Ni; 10-25Cr; 2.5-5Al; greater than 0.6, up to 2.5 total of at least one element selected from the group consisting of Nb and Ta; up to 3Mo; up to 3Co; up to 1W; up to 3Cu; up to 15Mn; up to 2Si; 0.007-0.15B; up to 0.05P; up to 1 total of at least one element selected from the group consisting of Y, La, Ce, Hf, and Zr; <0.3 Ti+V; <0.03N; and, balance Fe, wherein the weight percent Fe is greater than the weight percent Ni, and wherein said alloy forms an external continuous scale comprising alumina, and a stable essentially single phase FCC austenitic matrix microstructure, said austenitic matrix being essentially delta-ferrite free and essentially BCC-phase-free.