Electrolyte Composition for Distinguishing Corrosion Mechanisms in Steel Alloy Screening

The formation and breakdown of passive layers due to pitting corrosion are a major cause of failure of metal structures. The investigation of passivation and pitting corrosion requires two different electrochemical measurements and is therefore a time consuming process. To reduce time in material characterization and to study the interactions of both mechanisms, here, a combined experiment addressing both phenomena is introduced. In the presented electrolyte the different corrosion mechanisms are distinguished and investigated by cyclic voltammograms and polarization scans. The measurements show a passive area, metastable pit growth, and pitting corrosion as well as repassivation. The pitting corrosion is separated from additional dissolution processes and the standard deviation of the corrosion potential is smaller than in other electrolytes. Both passivation and pitting corrosion can be observed in one measurement without additional corrosion attacks. The deviation between different measurements of the same steel is small; this is helpful for the screening of similar materials.