Corrosion fatigue behaviour of aluminium alloy 6061-T651 welded using fully automatic gas metal arc welding and ER5183 filler alloy

The fatigue life of aluminium 6061-T651 at various applied stress amplitudes in the unwelded and welded condition was found to be significantly reduced on immersion in a 3.5% NaCl simulated sea water solution, compared to that measured in ambient air. The ratio of fatigue life in NaCl test solution to that in air increased as the stress amplitude decreased. The observed reduction in the fatigue life in the NaCl test solution was most likely due to the presence of pits which nucleated on second phase particles or precipitates. Welded joints performed using pulsed gas metal arc welding and ER5183 filler wire failed at the interface between the weld metal and the heat-affected zone as a result of a high pitting rate in this region.

► Plates of Al 6061-T651, welded using GMAW, were machined for fatigue testing.
► Fatigue life of welded joints was reduced on testing in air and 3.5% NaCl solution.
► Premature failure was due to pits initiating between precipitates and Al matrix.
► Welded joint tested in air failed in HAZ as crack initiated at coarse precipitate.
► Welded joints tested in NaCl solution, failed in HAZ/weld fusion line interface.