Prediction of Repassivation Potential of 3D Pits Using the 1D Pit Approach

In this study, cyclic potentiodynamic polarization (CPP) tests and one-dimensional (1D) pit tests were performed to evaluate the corrosion behavior of stainless steel 316L at different temperatures and identify the critical conditions for repassivation. Downward potential scans for 1D pit samples were performed at different potential scan rates to precisely determine the repassivation potential at different pit depths. The outputs from 1D pit experiments were used to predict repassivation potentials ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mi>E</mml:mi> </mml:mrow> <mml:mrow> <mml:mi mathvariant="normal">rp</mml:mi> </mml:mrow> </mml:msub> </mml:math> ) of three dimensional (3D) pits in bulk samples, assuming different pit geometries. Finally, these predictions were compared with the repassivation potentials obtained for bulk samples during CPP tests to verify the accuracy of predictions. This methodology provides a correlation between a controlled fundamental approach (1D pit tests) and a more practical and applied method (CPP tests on bulk samples, generating 3D pits). It also enhances the understanding of the variability in <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mi>E</mml:mi> </mml:mrow> <mml:mrow> <mml:mi mathvariant="normal">rp</mml:mi> </mml:mrow> </mml:msub> </mml:math> values obtained from the CPP technique, improving the reliability of this parameter.