Effects of applied potential on stable pitting of 304 stainless steel

•The effects of potential on stable pitting of 304 stainless steel were studied.•Pit morphologies and three-dimensional structures were dependent on potential.•Ratio of pit depth and width continuously changed with potential and time.•Pitting current density of a single stable pit increased with applied potential.•Ohmic potential drop existed between pit internal surface and bulk solution.

Effects of applied potential on stable pitting corrosion of 304 stainless steel were studied by potentiostatic polarization and three-dimensional video microscope. The results showed that pit mouth morphologies and three-dimensional structures were dependent on potential. Higher potentials resulted in more open pits. Pit volume, depth, and width increased with potential. The ratio of pit depth to width continuously changed with time and potential. The pitting current density of a single pit increased with potential, indicating that an ohmic potential drop presented between the pit internal surface and the bulk solution, but stable propagation was still controlled by corrosion products diffusion.