Growth of single corrosion pit in sputtered nanocrystalline stainless steel film

•Temperature controlled potentiostatic polarization was used to initiate single pit.•The pit formed on sputtered NCss film shows two-step growth behavior.•An appropriate model was set up to simulate the pit growth.•Both of the pit growth rate and current density at each stage are constant.•A special structure configuration of the pit cover was observed.

A single stable pit was initiated on the sputtered nanocrystalline stainless steel film. The pit shows two-step growth behavior. The pit growth rate and current density at each stage are constant. The interior morphology of the pit was observed. A series of outward-tilted concentric pit walls on the backside of the pit cover was discovered for the first time. These walls showed a constant spacing and presented an extremely regular configuration. Besides from the vestige of unreacted metal, the pit cover also contained the passive film which had originally covered the metal surface.