Computer Simulation of Single Pit Propagation in Stainless Steel under Potentiostatic Control

A model is proposed for the propagation of corrosion pits in stainless steel under potentiostatic conditions. The model is based on the requirement of a near-saturated local chemistry in the pit and uses an equation previously formulated for the anodic dissolution kinetics in this environment. Salt film precipitation, electrolytic migration, and transport outside the pit are each considered explicitly. Numerical simulations of pit growth have reproduced the experimentally observed characteristics of pitting, including development of a pit cover, spontaneous repassivation of metastable pits, increased stability at higher applied potentials, and a tendency for pits to become dish-shaped rather than hemispherical.