Field and Laboratory Evaluations 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-resistant austenitic steels designed to enable higher temperature recuperators. Field trials are in progress for commercially rolled foil with widths over 39cm. The first trial completed 3,000h in a microturbine recuperator with an elevated turbine inlet temperature and showed limited degradation. A longer microturbine trial is in progress. A third exposure in a larger turbine has passed 16,000h. To reduce alloy cost and address foil fabrication issues with the initial AFA composition, several new AFA compositions are being evaluated in creep and laboratory oxidation testing at 650°–800°C and the results compared to commercially fabricated AFA foil and conventional recuperator foil performance.