Pitting, lacy covers, and pit merger in stainless steel: 3D peridynamic models

摘要

A new three-dimensional peridynamic (PD) model is introduced for pitting corrosion damage. Based on simple mechanistic views of passivation, salt-layer presence, and passive-film rupture, the model simulates pitting corrosion damage in stainless steel in 3D, with autonomous formation of lacy covers. Computed lacy morphologies are strikingly similar to real pits. The model is validated against experiments. Merger of two 3D pits is studied and PD results compare well with experiments. The results imply that first-order mechanistic factors that determine corrosion rate, pit shape/size, and lacy cover morphology are those included in our model: diffusion, concentration-based damage, passivation, and salt-layer formation.