Development of Time-Frequency Analysis in Electrochemical Noise for Detection of Pitting Corrosion

Time-frequency analysis methods were developed for detection of pitting corrosion on stainless steel 321 (SS321) alloy in FeCl3 solution. Continuous wavelet transform (CWT), Hilbert-Huang transform (HHT), and Fourier decomposition method (FDM) were applied simultaneous for analysis of electrochemical noise data. Results of noise current show that each of the high-frequency and high-intensity peaks depends on the initiation stage in pitting corrosion, leading to formation of a hole with relatively high diameter. Also, the peak intensity is related to the pitting growth rate.