Mathematical modeling of the pit initiation process

The potential at which pitting corrosion begins under anodic polarization is a function of the environmental parameters. Determination of this characteristic potential enables prediction of pitting susceptibility under specific environmental conditions. The pitting potentials were determined experimentally for AISI 304 stainless steel for different values of chloride ion concentration, sulphate ion concentration, temperature and solution pH. A factorial design technique was employed to study the individual and interaction effects of parameters in order to investigate the multi-faceted nature of the pitting process. An empirical model was developed based on the result of the factorial analysis. The model emphasizes the fact that the pit nucleation process involves interrelated processes, and that the parameters behave differently with respect to each process.