Insight on corrosion behavior of friction stir welded AA2219/AA2195 joints in astronautical engineering

Corrosion behavior of friction stir welded Al-Cu alloy and Al-Cu-Li alloy joints were revealed via immersion, intergranular, exfoliation and electrochemical corrosion. Precipitation-driven corrosion was discussed based on experiments and theoretical modeling. The corrosion potential of the entire joint was nobler than base materials, which was mainly attributed to solid solution and precipitation evolution of high equilibrium potential elements. The macro/micro galvanic effect induced by the redistribution of copper was studied with a numerical model to explain the relationship between precipitation evolution and corrosion resistance. Reducing heat input by increasing welding speed was an effective strategy to improve corrosion resistance.