The Influence of Microstrain Evolution by Tensile Straining on Localized Corrosion of Al-Li Alloys 2099 and 2196

The localized deformation behavior during tensile straining (0 to 9 pct) and its effect on the corrosion properties of two third-generation Al-Li alloys (2099 and 2196) were investigated. Both electron backscatter diffraction and 2D micro-digital image correlation were used to examine site-specific effects of orientation and microstrain evolution during tensile straining. After straining, in situ tapping mode atomic force microscopy was used to study galvanic corrosion as it occurred in artificial seawater (3.5 pct NaCl). Regions of high microstrain corroded preferentially, and large, recrystallized grains in mostly unrecrystallized microstructures were highly detrimental to corrosion properties. Recommendations for improved thermomechanical processing and/or alloying to promote corrosion resistance of 2XXX series Al-Li alloys were considered.