Correlated pitting stages of 304 stainless steel with recurrence quantification analysis of electrochemical noise

Pitting corrosion behavior of 304 stainless steel (SS) in ferric chloride solutions with different concentrations was investigated by morphology observation and electrochemical noise (EN) analysis. The pitting stages were related to recurrence quantification analysis (RQA) of EN. It was found that the pitting stages of 304 SS in 0.02 and 0.3 M ferric chloride solutions mainly consist of metastable pitting and stable pitting through the morphology observation and wavelet analysis of EN. Through cluster analysis for the whole RQA variables the RQA results can accurately correlate with the pitting stages. The cluster results revealed that the metastable pitting of 304SS has high recurrence rate (RR) and determinism (DET), while the stable pitting has low RR and DET.