Abstract
Many airframe components contain complex geometries due to the fastening to adjacent structures. When exposed to marine environments, the geometries of these faying surfaces and fastener holes inherently aid in the trapping/wicking of the electrolyte into tight crevices typical of these component joining locations. Modern aircraft often involve the coupling of dissimilar metals in these structures. This combination of geometry and materials leads to the potential for a severe localized corrosion. The goal of this work is to develop a quantitative understanding of the effects of important external variables on the potential and current distributions within fastener holes in realistic thin film/galvanic couple configuration between a UNS A97050 component and a stainless steel fastener. A combination of experimental and modeling approaches was used to characterize important external factors in atmospheric localized corrosion. Significant geometric parameters are explored by using design of experiments. It has been found that crevice widths, and thickness of UNS A97050 plate have significant effects on the potential and current distributions based on the provided conditions. A preliminary FEM-based model has been developed by applying experimentally determined electrochemical kinetics. This preliminary model demonstrates that differences in boundary conditions will lead to different corrosion behaviors.
