Modeling the Influence of Microstructure on Corrosion Pit Growth and Resulting Stress Concentration

Localized corrosion like pitting corrosion can result in catastrophic failure of components due to transition of pits to stress corrosion cracks under loading. This transition is a product of pit morphology and mechanical behavior of the metal leading to regions of stress concentration from where cracks emanate. Fundamentally, both factors are dependent on the underlying microstructure, with pit morphology resulting from differences in growth rates across grains, and mechanical behavior resulting from elastic and plastic anisotropies across crystal orientations. This work presents a decoupled stress corrosion analysis, where at first pit growth simulations are performed at various locations in a steel microstructure, while taking into account the effect of microstructure through variation in corrosion potential. Subsequently the pit geometries are accommodated in mechanical loading simulations along with the underlying microstructure and anisotropic material properties to calculate stress distributions around the pit.