Initial stages of oxide growth on AM stainless steel exposed to a supercritical CO₂ environment

Wrought and additively manufactured (AM) 316 L stainless steel samples were exposed to a simulated Brayton cycle supercritical CO2 (sCO(2)) environment, at temperature of 450 degrees C and pressure of 76 bar in 99.999% CO2 for 2 weeks. The ground surfaces of wrought and AM 316 L specimens had average oxide thickness of 95 and 51 mu m, respectively, composed primarily of Fe and Cr oxides. An as-printed AM 316 L sample was also exposed to the sCO(2) environment and exhibited negligible oxidation during the 2-week exposure because of a thick Cr rich Mn silicate native oxide covering most of surface.