Corrosion behaviour of IN718 alloy produced by laser beam directed energy deposition (DED-LB) additive manufacturing in sodium chloride solution

This study investigates the effect of a chloride ion-rich environment on the global corrosion behaviour of IN718 alloy fabricated via Laser Beam Directed Energy Deposition (DED-LB). Electrochemical characterization was performed using open circuit potential (OCP), potentiodynamic polarisation curves (PPc), and electrochemical impedance spectroscopy (EIS) in 0.6 mol L −1 NaCl solution, and directly compared with conventionally processed IN718. Microstructural analysis revealed pronounced differences between conventional and DED-LB-fabricated IN718 in transverse, longitudinal, and top orientations, which clearly influence corrosion resistance. Despite the complex electrochemical response, the additively manufactured samples showed superior corrosion performance, highlighting the potential of the DED-LB technique. The transverse (i corr = 0.027 mA cm −2 ; E pitting = 1.046 V/SCE), longitudinal (i corr = 0.030 mA cm −2 ; E pitting = 1.076 V/SCE), and top (i corr = 0.057 mA cm −2 ; E pitting = 1.067 V/SCE) orientations all outperformed conventional IN718 (i corr = 0.058 mA cm −2 ; E pitting = 1.033 V/SCE). Finally, the manufactured samples exhibited higher impedance moduli values, irrespective of the immersion duration investigated (3 or 168 h), thereby evidencing the potential of the DED-LB technique. • DED IN718 shows superior corrosion resistance to the conventional alloy. • Microstructure and build orientation directly impact corrosion behaviour. • AM specimens exhibit enhanced stability in 0.6 mol L −1 NaCl environments. • DED method replicates and potentially improves IN718 chemical durability. • Porosity from the DED process influences the local corrosion mechanisms.