Computer Simulation of Crevice Corrosion of Stainless Steels: Influence of Alloying Elements and Film Depassivation

Crevice corrosion kinetics of AISI 430 and AISI 304 stainless steels (SS) are investigated using both electrochemical transients measurements and finite element method calculations. The experimental results lead to a quantitative picture of the well-known corrosion resistance difference between austenic and ferritic SS. A rational explanation of this behavior is provided by the modeling approach. The results lead to the formulation of critical conditions for crevice propagation in terms of dissolution current (I-G) and depassivation pH(d). In particular, the model estimates correctly the evolution of the corroded surface and fairly predicts the better crevice corrosion resistance of the austenitic grade, which is attributed to the slow dissolution rates in active conditions and to low pH(d).