Corrosion–Wear Behavior of Selective Laser Melted Inconel 718 Alloy Before and After Solution Heat Treatment and Double Aging

Abstract This study focuses on the corrosion–wear (tribocorrosion) performance of selective laser melted (as-built SLM) Inconel 718 in natural seawater and quantifies the benefit of a solution heat treatment and double aging (SHT + DA). Potentiodynamic polarization and potentiostatic tribocorrosion tests were conducted while continuously monitoring friction response, and the damaged surfaces were analyzed to clarify the dominant degradation mechanisms. Compared with the as-built condition, the SHT + DA condition exhibited a substantial reduction in corrosion current density (≈30–65%), together with a ∼50% lower friction coefficient and markedly reduced material loss, indicating a significantly mitigated corrosion–wear synergy under sliding. Microstructural characterization shows that SHT + DA promotes a more homogeneous microstructure with strengthened γ′/γ″ precipitation and a higher hardness (from 280.3 HV0.3 to 503.6 HV0.3), which provides improved load-bearing capacity during contact and supports more stable passivation during tribocorrosion. Overall, the results demonstrate that solution heat treatment and double aging reduce the sensitivity of SLM Inconel 718 to coupled mechanical–electrochemical degradation and improve surface durability for chloride-containing service.