4D Quantification of Surface Topography‐Dependent Corrosion Progression in Electron Beam Additive Manufactured 316L Stainless Steel

The anticorrosion performance of 316L stainless steel (SS) fabricated by electron beam powder bed fusion (EB‐PBF) is important for certain applications. In this study, the corrosion performance of EB‐PBF fabricated 316L SS in 6 wt% FeCl 3 solution is quantitatively investigated. Two samples, one with an as‐built rough surface and the other with a lathe‐machined smooth surface, undergo repeated immersion cycles, and are examined via X‐ray CT after each immersion. The temporal evolution of pits is quantitatively tracked in both samples. The results indicate that although the corrosion process progresses significantly faster in the rough‐surfaced sample than in the smooth one, the total corrosion volume in both samples follows a logistic growth curve with nearly identical growth exponents and comparable average volumes of new pits. The acceleration phase characterized by the reactivation of surface pitting and the coalescence of pits, is the primary driver of rapid mass loss in the material. The differences in both pit morphology evolution and overall corrosion rates between the two samples are attributed more to the density of active pits than to their individual growth rates. The quantitative corrosion evolution characteristics revealed in this study have implications for related engineering applications and corrosion monitoring.