Abstract
A corrosion- and creep-resistant austenitic stainless steel has been developed for advanced
recuperator applications. By optimizing the Al and Cr contents, the alloy is fully
austenitic for creep strength while allowing the formation of a chemically stable external
alumina scale at temperatures up to 900°C. An alumina scale eliminates long-term
problems with the formation of volatile Cr oxy-hydroxides in the presence of water vapor
in exhaust gas. As a first step in producing foil for primary surface recuperators, three
commercially cast heats have been rolled to 100 m thick foil in the laboratory to
evaluate performance in creep and oxidation testing. Results from initial creep testing are
presented at 675°C and 750°C, showing excellent creep strength compared with other
candidate foil materials. Laboratory exposures in humid air at 650–800°C have shown
acceptable oxidation resistance. A similar oxidation behavior was observed for sheet
specimens of these alloys exposed in a modified 65 kW microturbine for 2871 h. One
composition that showed superior creep and oxidation resistance has been selected for
the preparation of a commercial batch of foil. DOI: 10.1115/1.4002827
