Microstructure and Corrosion Behavior of Friction Stir Welded Al Alloy Coated by In Situ Shot-Peening-Assisted Cold Spray

To improve the corrosion resistance of friction stir welded (FSW) joints, in situ shot-peening-assisted cold spray coating was applied to the surface of FSW joints. The microstructure and corrosion behavior of the coatings were investigated. The results showed that a dense coating was obtained by cold spraying technology. Moreover, the use of in situ shot-peening-assisted technology significantly reduced the porosity of the coating, which has a positive impact on the microstructure and the mechanical performance. Exfoliation corrosion tests showed that the coating affected positively on the corrosion resistance. On the coated surface, the craters caused by shot-peening particles were corroded in the form of exfoliation corrosion, while the exposed particles were corroded in the form of intercrystalline corrosion. This work provides a new approach to the corrosion protection of FSW joints.