Performance of alumina-forming austenitic steels, Fe-base and Ni-base alloys exposed to metal dusting environments

A series of conventional Fe- and Ni- base, chromia- and alumina- forming alloys, and a newly developed creep-resistant, alumina-forming austenitic (AFA) steel were evaluated in metal dusting environments with a range of water vapor contents. Five 500h experiments have been performed at 650°C with different water vapor contents and total pressures. Without water vapor, the Ni-base alloys showed greater resistance to metal dusting than the Fe-base alloys, including AFA. However, with 10-28% water vapor, more protective behavior was observed with the higher-alloyed materials and only small mass changes were observed. Longer exposure times are in progress to further differentiate performance.