The Impact of Fusion Welds on the Ultimate Strength of Aluminum Structures

In the quest to minimize lightship weight, structural researchers and engineers are turning to limit-state design techniques for aluminum high-speed vessels (HSVs). In adapting techniques used for other materials for use on aluminum, one of the central problems faced is how to account for the reduced strength region in and around fusion welds in aluminum structures. The common marine aluminum alloys in both the 5000 and 6000 series alloys lose a significant portion of their strength when fusion welded. The properties of fusion welds in common marine alloys are reviewed in this paper, and previous work in this field is summarized along with new investigations into the tensile strength of such welds. Examples of loss of strength in tensile loading are given along with the implications for limitstate formulation and structural strength.