Mechano-electro-chemical modelling of stress enhanced corrosion
File(s)
Author(s)
Makuch, Maciej
Type
Thesis
Abstract
Austenitic stainless steels are used across multiple industries for corrosion resistance. The FCC crystal structure of austenitic steel enables high work hardening capacity and excellent ductility, while the high chromium content of stainless steel forms a protective oxide. However, a chloride-rich environment can break the passive film. This endangers the steel to localised corrosion and stress corrosion cracking (SCC). In this work, a new generation corrosion damage model is proposed to capture the evolution of SCC mechanistically. Firstly, a nonlinear phase-field model is developed to simulate corrosion damage. The model links the surface polarisation variation with the charging kinetics of an electric double layer (EDL) to the mesoscale transport. The motion of the electrode-electrolyte interface is governed by the kinetic rate theory, as described by the Butler-Volmer equation. The framework developed reproduces experimental measurements of both pit kinetics and transient current density response. The model enables more accurate information on localised environmental response in terms of the distribution of electric potential and charged species. Secondly, the phase-field model is developed into a new mechano-electro-chemical framework for simulating SCC in polycrystalline materials. The formulation accounts for both electrochemical and mechanical anisotropies. The introduction of EDL significantly enhances the computational efficiency of fully coupled SCC studies. The introduction of crystallographic dissolution recreates experimentally observed pyramidal pits in 3D geometry. The stress concentration resulting from the non-uniform shapes of pits accelerates the propagation of SCC damage. It is demonstrated that incorporating anisotropic elastoplastic material behaviour is crucial for reproducing the complex SCC morphologies observed experimentally. Plastic deformations predicted by the crystal plasticity model promote defect tip branching and early initiation at low loads, features that are not captured by conventional isotropic models based on von Mises plasticity. The proposed framework is general and can be extended to a wide range of material-environment systems.
Version
Open Access
Date Issued
2025-10-02
Date Awarded
2026-03-01
Copyright Statement
Attribution-NonCommercial 4.0 International Licence (CC BY-NC)
License URL
Advisor
Wenman, Mark R.
Martínez-Pañeda, Emilio
Sponsor
Engineering and Physical Sciences Research Council
Grant Number
EP/5023844/1
Publisher Department
Department of Materials
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)