The effect of mechanical surface patterning on filiform growth characteristics

Abstract

The effect of surface patterning on filiform corrosion characteristics has been studied using both as-rolled material and re-worked AA2024 material and following the filament dimensions and spatial density as a function of time. It was shown that the direction of the filiforms corresponds with the directions of the deepest micro-trenches. Both chemistry-based and geometry-based mechanisms are presented to explain the preference of the direction of propagation. The tendency to filiform corrosion has been quantified by the site density and the average filament length. The lower growth rate on the as-rolled material was attributed to stronger mechanical anchoring of the coating. The option of imposing macro surface patterns to confine filiform corrosion attack has been explored successfully.