Multimodal Characterization of AM316 Crevice Corrosion

Non-destructive 3D characterization techniques are particularly important for materials synthesized by advanced manufacturing techniques that display disparity from their namesake identifiers (e.g. UNS S31600 or SS316). This is a particular concern for non-equilibrium materials, such as additively manufactured (AM) alloys, that often contain porosity, surface roughness, phases, microstructures and internal stress not exhibited in wrought or cast counterparts. This work examines chemical, electrochemical and microstructural evolution of AM and wrought SS316 under a crevice corrosion configuration. These results include chronoamperometric signatures, potentiometric sensors to track pH and X-ray computed micro-tomography 3D reconstructions during crevice corrosion. In-situ measurements are combined with initial and post-mortem SEM and EDS to better understand two AM316 materials that exhibit ennobled and more active behavior relative to wrought SS316. Local composition and phase heterogeneity at different length scales is shown to be a primary driver for contrasting crevice corrosion performance.