Corrosion, the underlying driver of SCC, is an electrochemical degradation process that irreversibly deteriorates metals, typically in the presence of oxygen and moisture. SCC mechanisms are often categorised into two main groups. The first includes models driven by anodic corrosion reactions at the crack tip, such as active path dissolution and the film rupture–dissolution–repassivation (FRDR) mechanism. The second involves cathodic-driven processes associated with hydrogen ingress, including hydrogen-enhanced decohesion (HEDE), hydrogen-enhanced localised plasticity (HELP), and adsorption-induced dislocation emission (AIDE). These mechanisms often interact synergistically and vary significantly depending on the material and environmental conditions, adding to the complexity of SCC.

Our research focuses on the transition from pitting corrosion to crack initiation and growth—a crucial stage in SCC progression. While uniform corrosion can often be mitigated with corrosion-resistant coatings, pitting corrosion originates from localised defects or pits and presents a greater challenge. Alloying composition adjustments can provide some resistance, but the pit-to-crack transition remains an open issue requiring deeper investigation.

We leverage phase field theory to model and regularise sharp corrosion interfaces, providing a unified and robust framework for simulating the complex interplay of mechanics, electrochemistry, and material degradation. Unlike existing models that rely on phenomenological coupling between mechanics and electrochemistry, our approach is based on variationally consistent mechanistic coupling. This enables a more rigorous and predictive understanding of the SCC process, addressing key gaps in existing modelling efforts.

Our goal is to develop mechanistic models for stress-corrosion cracking, enabling virtual testing to complement and enhance experimental approaches. By providing detailed insights into the pit-to-crack transition and advancing predictive capabilities, our work aims to contribute to the design of more durable materials and the mitigation of SCC in critical engineering applications.