Simulation of metastable corrosion pit development under mechanical stress

A cellular automata model coupled with finite element method is used to describe metastable pitting corrosion growth and its transition to stability of stainless steel under mechanical stress. The model includes anodic dissolution, passivation, diffusion and hydrolysis of salt film. The local stress and strain distributions on the pit surface are analyzed by the finite element method in real time during the pit growth. The effects of local stress and strain on anodic current at every micro-region of the pit surface obtained by Gutman model are used as the boundary conditions for the cellular automata model. The result shows that the growth rate of metastable pitting corrosion under stress is far higher than that under no stress. The effects of rupture time and rupture extent of pit cover and diffusion of hydrogen ions on current transients under stress and no stress are analyzed. (c) 2012 Elsevier Ltd. All rights reserved.