Development of cast alumina-forming Austenitic stainless steel alloys for use in high temperature process environments

There is significant interest in the development of alumina forming, creep resistant alloys for use in various industrial process environments. It is expected that these alloys can be fabricated into components for use in these environments through centrifugal casting and welding. Based on the successful earlier studies on the development of wrought versions of Alumina Forming Austenitic (AFA) alloys, new alloy compositions have been developed for cast products. These alloys achieve good hightemperature oxidation resistance due to the formation of protective Al₂O₃ scales while multiple secondphase precipitation strengthening contributes to excellent creep resistance. This work will summarize the results on the development and properties of a centrifugally cast AFA alloy. This paper highlights the strength, oxidation resistance in air and water vapor containing environments, and creep properties in the as-cast condition over the temperature range of 750°C to 900°C in a centrifugally cast heat. Preliminary results for a laboratory cast AFA composition with good oxidation resistance at 1100°C are also presented.