On the occurrence of filiform corrosion on organic coated carbon steel exposed to cyclic aging test

Abstract

ABSTRACT Filiform corrosion is one of the possible failure mechanisms of organic-coated steel. Beyond cathodic delamination, filiform corrosion causes paint detachment and the dramatic loss of the protective properties given by the applied paint. Since both failure mechanisms occur during in-field exposure (depending on the environment), when assessing the performance of the protective paint by lab scale tests, we must be aware of the failure mechanism we induce with different accelerated aging cabinets. In this study, we investigate the effect of prohesion test on the initiation and propagation of filiform corrosion. We highlight the concurrent development of filiform corrosion and cathodic blistering, which includes the change between the cathodic and anodic delamination front, during an accelerated aging procedure that cycles between saturated humidity and dry stages. The role of the presence of aggressive contaminants (Cl− and SO42−) is discussed. According to our findings, cyclic aging tests seem to better stick to the failure mechanism occurring during in-field exposure, particularly due to the wet/dry cycles.