Evolution of Surface Oxides of UNS S13800 during Cathodic Polarization in Chloride Solutions

Solutions arising from atmospheric processes can have varying chloride concentrations, often higher than seawater as salt deposits accumulate in thin layer electrolytes. Understanding the corrosion behavior of stainless-steel fastener components is important to predicting its behavior in a galvanic couple with less noble materials. Here we have focused on the cathodic kinetics of UNS S13800 stainless steel over a range of chloride concentration electrolytes. The different oxides formed under these varying conditions are studied using surface analytical techniques. This information is then used to inform a model for fitting of the potentiodynamic polarization curves. The evolving composition of the surface oxide affects the polarization curve in the activation region of the oxygen reduction reaction. This additional cathodic current is accounted for in the model and the different reaction components of the polarization curve are extracted and analyzed. Acknowledgments The U.S. Naval Research Laboratory sponsored this project as part of their base program. The views and conclusions contained herein are those of the authors and should not be interpreted as necessarily representing the official policies or endorsements, either expressed or implied, of the Office of Naval Research, the U.S. Navy, the Department of Defense, or the U.S. government