Cyclic potentiodynamic polarization (CPP) is a well known characterization tools in the field of corrosion science. However, the use of repassivation has been utilized on a limited scale to characterize pitting damage of aluminum alloys. The aim of this work was to apply repassivation analysis to determine extent of pitting damage for UNS A97075 coupons submerged in ASTM seawater. In this context cyclic potentiodynamic polarization experiments were used to assess the repassivation Tafel slope, βa-rp, the related effective charge transfer coefficient, pit transition potential, Eptp, and the associated current density at Eptp, iptp. With the exception of Eptp, these variables were found to correlate with experimental parameters of temperature, rolling direction, surface finish and reversal current density. Perhaps most exciting was the improved correlation found between repassivation parameters and pitting charge density. The repassivation Tafel slope and effective charge transfer coefficient displayed a semi-log correlation with charge while iptp displayed a linear correlation. The pitting charge density is equivalent to mass loss and therefore these results provide critical new utility for repassivation analysis to determine extent of pitting damage for UNS A97075. Ongoing work is currently extending this effort to accelerated atmospheric corrosion experiments.
