While the mechanical joint strength efficiencies of fusion welded high strength aluminum alloys have been considerably improved by new welding processes, the uncertainty of the lowered corrosion resistance of the welded alloys due to the deleterious effect of the heat involved has been a major obstacle to the extended use of welded aluminum alloys of the 24S and 75S types for aircraft structures.
This article discusses the metallurgical structures resulting from the fusion welding of aluminum alloys and correlates these structures with the resulting corrosion data. The results of several investigations on the corrosion resistance of fusion welded 24S, 61S and 75S aluminum alloys are reported. Tensile strength comparisons of bare and clad welded alloys exposed to corrosive mediums in the as-welded, aged and reheat treated conditions are made.
The protective value of cladding and the restoration of the original parent metal structure by reheat treatment are demonstrated by the accumulated corrosion data for the high strength wrought aluminum alloys used in aircraft construction.
Conclusions from these laboratory and outdoor exposure corrosion studies are made and recommendations are offered for the fusion welding of the high strength aluminum alloys with the optimum corrosion resistance.
