Hot corrosion behavior of additively manufactured stainless steel 316L and Inconel 718 in MgCl2/KCl/NaCl chloride salts at 700 °C

Two additively manufactured (AM) materials, i.e., stainless steel 316 L (SS316L) and Ni-base superalloy Inconel 718 (IN718), have been exposed to MgCl 2 -KCl-NaCl (47.1-22.7-30.2 mol%) salts at 700 °C to investigate their corrosion behavior. Corrosion tests were conducted using SS316L processed by laser metal deposition (LMD), IN718 by laser powder bed fusion (PBF-LB) as well as conventionally processed counterparts. The obtained results reveal that LMD SS316L is characterized by inferior corrosion resistance, mainly due to the segregation of δ-ferrite at grain boundary (GB). Two different types of corrosion morphologies, uniform corrosion and GB-driven corrosion, are observed in both AM and the conventionally processed IN718 samples. The GB-driven corrosion is accelerated by the evolution of δ-phase in case of IN718. • The LMD SS316L is less corrosion resistant than commercial SS316L in MgCl 2 -KCl-NaCl • The corrosion attack of LMD SS316L is promoted by the δ-ferrite at grain boundary • PBF-LB IN718 shows the corrosion behavior similar to the commercial IN718 • Two types of corrosion are observed in PBF-LB and commercial IN718