A distinct role of microstructure on hot corrosion behaviour of additively manufactured IN718

The influence of LPBF-IN718 microstructure on hot corrosion behavior was studied at 650 °C. The H-IN718 with <001> oriented grains undergo more weight changes than V-IN718 with <110> oriented grains. Detailed characterization analysis corroborates that Rapp-Goto fluxing and sulphidation mechanisms are operating in LPBF-IN718 with 3SM. Further, GDOES confirms the sulphur gradient existence between Air/3SM and 3SM/H-IN718 interfaces. It suggests that <001> oriented grains serve as preferred sites for ion adsorption and reactions, which might facilitate the sulfur diffusion more effectively than other grain orientations. As a result, oxy-anions generated during sulfidation enhance the fluxing mechanism, thus increasing weight gain in H-IN718.