Propagation of Intergranular Corrosion Defects in AA 2024-T351 Evaluated by a Decrease in Mechanical Resistance

This study deals with propagation kinetics of intergranular corrosion defects. It complements previous works focused on the development of a procedure called "T2C (Tensile Test for Corrosion)." This procedure was previously applied on samples of 2024 alloy submitted to a continuous immersion test in 1 M NaCl solution. The aim of the present study was to determine if a modification in the way in which the samples are corroded impacts the ability to use this procedure. Therefore, the applicability of the T2C procedure to cyclic corrosion tests was evaluated. Intergranular corrosion defects developed during cyclic corrosion tests were characterized by using a statistical approach. The geometry of the tensile specimens was optimized to allow the T2C procedure to be applied in conditions expected as adequate. Results showed that, for cyclic corrosion tests, due to the branched morphology of the intergranular corrosion defects and the effects of hydrogen embrittlement, the T2C procedure cannot provide an estimation of the mean depth of the intergranular corrosion defects. However, depending on the cyclic corrosion tests, it allowed the maximal depth of the intergranular corrosion defects or the thickness of the corrosion-induced damage zone (defects + hydrogen affected zone) to be determined.