Localized corrosion and stress corrosion cracking of friction stir welded 7075 and 7050

The localized corrosion and stress corrosion cracking of high strength aluminum alloys 7075-T651 and 7050-T7451 friction stir welds were examined in the weld transverse and longitudinal orientation using conventional electrochemical measurements, corrosion immersion tests and constant extension rate testing. The weld zones in both alloys were found to be more susceptible to corrosion compared to the unaffected parent materials. The heat affected zones of the weld were found to be the most susceptible to corrosion and stress corrosion cracking for 7075-T651, while in 7050-T7451, the TMAZ-nugget boundary exhibited the greatest corrosion susceptibility. In constant extension rate tests, 7075-T651 friction stir welds generally exhibited better cracking resistance than 7050-T7451 welds, even though the 7075-T651 the parent metal exhibited a lower resistance than the parent 7050-T7451.