Evaluation of Commercial and Next Generation Alumina-Forming Austenitic Foil for Advanced Recuperators

Alumina-forming austenitic (AFA) steels represent a new class of corrosion- and creep-resistance austenitic steels to enable higher temperature recuperators. Several commercial batches of the first AFA composition have been produced with different thicknesses and widths over 39cm. This commercial AFA foil was successfully folded by two manufacturers. Creep and laboratory oxidation results at 650°-800°C are presented to compare to conventional recuperator alloy performance. While this initial effort was successful, concerns with cost and ease of production suggested that a leaner AFA composition with a lower final annealing temperature would be more attractive for commercial applications. Therefore, several new AFA compositions are being evaluated in laboratory trials and compared to the initial material for down selection of a better AFA composition for commercialization.