In-situ investigation on the pitting corrosion behavior of friction stir welded joint of AA2024-T3 aluminium alloy

The surface corrosion behavior of an AA2024-T3 aluminium alloy sheet after friction stir welding was investigated by using an “in-situ observation” method. SEM observations showed that the density and degree of the pitting corrosion in the shoulder active zone were slightly larger compared to the other regions on the top surface. The origins of the pitting corrosion were in the regions between the S phase particles and the adjacent aluminium base. The effect of Al–Cu–Fe–Mn–(Si) intermetallic compounds on the pitting corrosion was attributed to their high self-corrosion potential which induced the anodic dissolution of the surrounding aluminium matrix.