Quasi-in-situ ex-polarized TEM observation on dissolution of MnS inclusions and metastable pitting of austenitic stainless steel

The pit initiation and growth processes occurring in austenitic stainless steel are included in the passive region of polarization curve. However, polarization measurements do not yield surface morphological insights, which limit the ability to provide a comprehensive picture of the corrosion process. A quasi-in-situ ex-polarized TEM observation method is designed to elucidate the microstructural evolution corresponding to the characteristic regions of the electrochemical polarization curve. This work shows the potential and advantage of combining TEM technique and the traditional electrochemical methods in investigating the initiation of localized corrosion.