Statistical analysis of metastable pitting events on carbon steel

The metastable pitting behaviour of galvanically coupled and potentiostatically controlled A516-70 carbon steel in a chloride containing solution has been statistically analysed. It is shown that the pitting activity, indicated by the pit initiation rate, depends on immersion time, applied potential, and chloride concentration. There is a strong correlation among the pitting events at a high pitting activity, where the metastable pitting events follow non-Poissonian behaviour and a previous pit has an influence on subsequent pitting events. When the pitting activity decreases, the correlation decreases and approaches the Poisson distribution. (C) 2000 IoM Communications Ltd.