High temperature oxidation of inconel 939 produced by additive manufacturing.

High temperature oxidation of additively manufactured (Laser-powder bed fusion) IN939 (AM IN939) was studied at 900°C in dry air for 168 hours. AM IN939 cut parallel/perpendicular to the building direction, including conventionally manufactured (CM) IN939 were exposed to assess the influence of AM microstructure and its inherent anisotropy on oxidation properties. Microstructural anisotropy had no significant impact on oxidation properties. AM and CM IN939 exhibited nearly identical mass gains, yet local spallation was observed in the former. Further investigation involved oxidation of heat-treated AM IN939, revealing improved adhesion, possibly due to transformation of fine dendritic/cellular structure into coarse equiaxed grains. • Highly similar oxidation resistance of conventional (CM) IN 939 and AM IN939 at 900°C. • Anisotropy did not significantly affect the oxidation behavior of AM IN939. • As-built AM IN939 showed local spallation while the oxide was adherent on CM IN939. • AM IN939 is heat-treated to investigate the effect of microstructure on oxidation behavior. • The heat-treatment minimized spallation and buckling of oxide scales. [ABSTRACT FROM AUTHOR]