Laboratory investigation of microbiologically influenced corrosion of 2205 duplex stainless steel by marine Pseudomonas aeruginosa biofilm using electrochemical noise

The corrosion mechanism of a 2205 duplex stainless steel (DSS) in Pseudomonas aeruginosa inoculated medium was investigated using the information of electrochemical current noise (ECN) transients derived from Hilbert spectra and surface analysis. The pit depths from confocal laser scanning microscopy (CLSM) were analyzed stochastically. Results showed that metastable pitting and stable pitting occurred simultaneously, and they were controlled by different mechanisms in the presence of P. aeruginosa. Metastable pitting occurred in the region uncovered by P. aeruginosa unlike stable pitting. P. aeruginosa likely dissolved the passive film and produced soluble CrO3, leading to stable pitting.