Does additive manufacturing cause intergranular oxidation attack in high-temperature alloys? Case study of Ni-base alloy IN625

High-temperature oxidation of additively manufactured (AM) Ni-base alloy IN625 has been studied in air and Ar-4 %H 2 -2 %H 2 O for up to 1000 h at 900 and 1000 °C. AM was produced from the same conventionally manufactured (CM) reference alloy batch to retain the chemical composition and minimize batch-to-batch variation. The AM alloy developed subsurface porosity during oxidation, but the intergranular voids remained closed and unoxidized because of good adhesion of the Cr 2 O 3 scale to the metal. Contrary to many literature studies, AM had no effect on either the oxide growth kinetics or the oxide adherence. The chemical composition of the currently studied AM alloy close to the CM, especially the minor elements e.g. Al, Mn, Si and Ti, is believed to be the key factor preventing oxide decohesion and intergranular oxidation attack. • Additively manufactured (AM) alloy IN625 was fabricated from the same conventionally manufactured (CM) alloy batch. • Chemical compositions of CM and AM were virtually identical except for the increased content of interstitial O, N, and C. • AM alloy IN625 formed intergranular voids in the near-surface region but this did not result in intergranular oxidation attack (IGOA). • AM had no effect on the oxidation kinetics of IN625 when fabricated from an alloy batch not suffering from IGOA. • Differences in minor elements (Al, Mn, Si, Ti), not the AM process, are believed to trigger oxide scale decohesion and IGOA.