Estimation of the pitting stability transition according to the electrochemical noise transient analysis

• The prolonged EN transient observed in the case of free corrosion of 316 L SS in 0.01/0.05 M FeCl3 solution at room temperature did not correspond to the stable pitting process. • The ultralong EN transient may be attributed to either lateral propagation of damage to the passive film or slow dissolution occurring under deposits in localized areas. • The local current growth rate and amplitude estimated from the EN signals can be utilized to assess the likelihood of stable pitting. Some approaches or parameters were employed to indicate the stage of stable pitting such as the energy distribution obtained by the wavelet analysis or the Hilbert spectra, the recurrence quantitative parameters obtained from the recurrence analysis, and the noise resistance as well in the electrochemical noise analysis. The pitting current density may be a key parameter for the stable pitting estimation which determined the dissolution-diffusion sustainable dynamic balance in the pit according to the theoretical framework proposed by Li, Scully, and Frankel. While the pit stable product defined the critical transportation condition under the high pitting current density. The pitting current growth rate as well as its amplitude was adopted to indicate the stable pitting transition according to the electrochemical transient analysis during the stainless-steel pitting process, which may provide the quantitative indicator agreed with the theoretical framework.