Extended Abstract
The corrosion resistance of Inconel 625 Ni-based superalloy additively manufactured (AM) by laser-directed energy deposition (L-DED) process was assessed by cyclic polarization tests in NaCl 3.5% media using virgin (as-received) and reused gas-atomized powder. The initial microstructure and corrosion mechanism were investigated by optical and scanning electron microscopy and the chemical composition by energy dispersive spectroscopy analysis. Along with the AM L-DED manufacturing, both sample conditions developed a dendritic microstructure with the presence of Mo- and Nb-rich Laves phase in the interdendritic region. In the electrochemical corrosion study, similar polarization curves were recorded for both samples that exhibited analogous polarization resistance and corrosion rates. Nevertheless, the corrosion potential of samples manufactured with virgin powder was slightly more noble. Both samples showed a trend to passivate in the testing NaCl 3.5 % solution and the Inconel 625 powder reuse had no detrimental impact on the measured pitting potential. Evaluating the sample surfaces aspects, uniform and pitting corrosion mechanisms were detected, with the latter being preferentially located in the Mo-depleted dendritic region.
