Characterisation of microstructure, mechanical properties and corrosion behaviour of an AA2219 friction stir weldment

Abstract

A friction-stir weldment of AA2219-T87 aluminium alloy was characterized for its microstructure, mechanical properties, corrosion resistance and stress corrosion cracking behaviour. The dissolution and coarsening of the strengthening precipitates in the weld nugget and TMAZ/HAZ regions, respectively, had resulted in the softening of these regions; nevertheless, the weld joint was found to have an efficiency of around 72%. The general corrosion behaviour of the weld nugget was superior to that of the parent. The TMAZ/HAZ regions, and the weld nugget were found to have been galvanically protected in the immersion tests. Both the parent alloy and the friction stir weldment specimens exhibited a good resistance to stress corrosion cracking in 3.5% NaCl solution as was demonstrated by slow strain rate tensile tests performed at nominal strain rates of 10−6 s−1 and 10−7 s−1.