Fatigue strength of new explosively welded steel-aluminum transition joint used in ships

The paper presents the results of tension-compression fatigue tests of a new steel-aluminum welding transition joint with a titanium Grade 1 interlayer. The new explosive welded transition joint prototype used as a connector in the shipbuilding industry has been developed by the Explomet company situated in Opole-Poland. The paper discusses the advantages of the use of these types of connectors in comparison to the classical approach of using the bolted joints as connectors between non-weldable materials in ships. We are emphasizing its eco-friendly effect on fuel consumption by lowering the weight of the whole structure. The thickness of the new prototype of the transition joint is lower than the standard thicknesses used by other manufacturers. The multilayer metallic composite was subjected to microstructural analysis. Factors influencing fatigue durability were analyzed and the basic analysis of fatigue cracks observed during tests was presented in form of crack propagation curves. The obtained fatigue results show that in most of the analyzed cases, the crack initiation is spotted in the heat-affected zone. According to the standard procedure of fatigue testing none of the prototype test specimens would fulfill the requirements set in the ABS standard used for the testing. This is crucial information in terms of the modification of the welding technology of the transition joint which has to be adapted. Nevertheless, the presented results show that there is a place for improvement in the used welding technology.