Mechanism of crevice corrosion in historic riveted steel structures

Abstract Crevice corrosion is a localized form of corrosion, particularly common in riveted steel structures. While oxygen depletion and local acidification within crevices are well-established phenomenological features, the underlying reaction pathways and their spatial coupling remain insufficiently understood. Here, we present a mechanistic investigation into the initiation and spatiotemporal progression of crevice corrosion by combining real-time, spatially resolved electrochemical monitoring using coupled multi-electrode array setup, with chemical characterization (SEM, XRD) and thermodynamic modeling techniques. Findings reveal that local pH changes observed arise from a migrating cascade of coupled reactions across the crevice geometry that is influenced by the speciation of Fe(II) and Fe(III) in the electrolyte. Thermodynamic analyses demonstrate how these conditions drive the selective precipitation of corrosion products, leading to the development of an alkaline (pH > 12) region close to and an acidic (pH <5) region further away from the crevice opening. The here presented mechanistic investigation is (i) consistent with short-term laboratory measurements and (ii) independently validated through corrosion products sampled from a crevice in a 140-year-old riveted steel structure. By linking electrochemical dynamics with thermodynamic modelling, this work provides an experimental and computational framework for developing predictive models and targeted mitigation strategies in heritage steel structures.