Corrosion behavior of multi-layer friction surfaced structure from dissimilar aluminum alloys

Friction surfacing (FS) is a solid-state coating technology for metallic materials, where the deposition of a consumable material on a substrate is enabled via friction and plastic deformation. The deposited layer material commonly presents a significantly refined microstructure, where corrosion could be an issue due to this grain refinement within the layer deposited, possibly creating micro galvanic pairs. The present work investigates the corrosion behavior of the FS deposited material as well as stud base material and substrate using cyclic polarization tests and open circuit potential (OCP) monitoring. Comparing the FS deposited material and the respective consumable stud base material (both AA5083), the grain size is correlated with the results from the corrosion tests, where the deposited material shows more equiaxed and refined grains in comparison to the stud base material. The cyclic potentiostatic polarization tests showed that the stud base material is more resistant to pitting nucleation presenting smaller pits and a lower amount of pits compared to deposited material and substrate. As a complement to OCP test, the stud base material is also more stable on a chloride solution compared to the substrate and the deposited material.