Evaluation of the Local Chloride Concentration and the Local Mechanical Stresses in Intergranular Damages Grown on a 2024 Aluminum Alloy

Abstract

The corrosion behavior of a 2024 T351 aluminum alloy exposed to a chloride solution was studied in the present paper. The work was focused on the effect of an environmental and thermal cyclic exposure to corrosive media and aimed to identify the main parameters explaining the changes observed between continuous and cyclic immersion tests. Optical and scanning electron microscope observations showed an increase of the intergranular corrosion damage with the extension of the corrosion from the grain boundaries to the subgrain boundaries for samples exposed to cyclic tests. An experimental set-up, including a laser beam, allowed mechanical stresses induced by the solidification of the electrolyte trapped in the corrosion damage during exposure to negative temperatures to be revealed and the chloride concentration of the electrolyte to be determined. Results were helpful in proposing corrosion mechanism during thermal and environmental cyclic exposure to chloride solutions.