Phase field modelling of pitting and stress corrosion cracking (COMPLAS 2021 talk, Martínez-Pañeda)

COMPLAS 2021 talk (16th International Conference on Computational Plasticity). Invited Session: Size Effects in Plasticity and Fracture

Phase field modelling of pitting and stress corrosion cracking
Emilio Martínez-Pañeda. Imperial College London
Chuanjie Cui. Imperial College London & Tongji University

ABSTRACT
Non-local phase field models have had a significant impact in many interfacial problems, including the modelling of microstructural evolution and fracture mechanics (see, e.g., [1] and Refs. therein). In this work, we will show how phase field modelling can also open new horizons in a scientifically-challenging phenomenon of notable technological importance: corrosion damage [2]. The phase field paradigm can be exploited to enable tracking the aqueous electrolyte - solid metal interface. This enables predicting explicitly, as a natural by-product of the simulation, the nucleation of pits, the pit-to-crack transition and stress corrosion cracking. We will present the first formulation capable of capturing the film rupture–dissolution–repassivation mechanism and the role of mechanical fields in enhancing corrosion kinetics. Several 2D and 3D boundary value problems of particular interest have been addressed to showcase the predictive capabilities of the model, revealing an excellent agreement with analytical solutions and experimental measurements. The results that will be presented show how the model can naturally capture: (i) the transition from activation-controlled corrosion to diffusion-controlled corrosion, (ii) the sensitivity of interface kinetics to mechanical stresses and strains, (iii) the role of film passivation in reducing corrosion rates, and (iv) the dependence of the stability of the passive film to local strain rates. Finally, we will describe ongoing efforts towards generalising the model to capture both stress corrosion cracking, as in dissolution and anodic-driven fractures, and hydrogen embrittlement.

REFERENCES
[1] P. Kristensen, C.F. Niordson, E. Martínez-Pañeda, “An assessment of phase field fracture: crack initiation and growth”, Philos. Trans. R. Soc. London, Ser. A 379, 20210021 (2021)
[2] C. Cui, R. Ma, E. Martínez-Pañeda, “A phase field formulation for dissolution-driven stress corrosion cracking”, J. Mech. Phys. Solids, 147, 104254 (2021).