Salt spray fog ageing of Al/Steel structural transition joints for shipbuilding

Aluminum superstructures can be connected to steel hulls by means of Structural Transition oints made by explosion welding, which offer a good compromise between weldability and mechanical properties. However, in severe environmental conditions, the corrosion phenomena could influence the mechanical behavior of this kind of welded joints requiring further investigation. The aim of the paper is to assess the mechanical performance and failure mechanisms, induced by aging in marine environment, of Al/Steel Structural Transition Joints. A commercial bar for shipbuilding, made of ASTM A516 structural steel, AA5086 aluminum alloy and provided with an intermediate layer of pure aluminum, exposed to a salt fog spray condition (according to ASTM B 117) was analyzed. Three point bending experimental tests were carried out on the corroded specimens. A full-field technique, such as the Digital Image Correlation, was applied during the experimental tests to detect the displacement and strain patterns of the different metals.