PSI - Issue 79

Benjamin Möller et al. / Procedia Structural Integrity 79 (2026) 493–500

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premature failure. The streak-like structures observed indicate typical solidification patterns during the welding process. Based on their structure and chemical composition, the streaks indicate a microstructure of α mixed crystals, which form when the aluminum content is slightly higher. The streak-like microstructure is more prevalent in the lower part of the weld seam, as solidification occurs more rapidly and the aluminum cannot distribute itself as quickly in the weld metal. The comparatively homogeneous microstructure does not exhibit any intermetallic phases in the upper joining partner. In the lower area, however, such phases form in the transition to the aluminum alloy.

Figure 2. Cross-section and microstructural images of the laser-welded adapter.

3. Tensile testing and results The adapters are subjected to quasi-static loading using an MTS Landmark tensile testing machine at a test speed of 10 mm/min (distance-controlled) and, in addition to the max. tensile force F t , the fracture type and fracture location of the individual samples are determined. The adapter specimens used have a width of 22 mm and a length of 260 mm. To perform the tensile test, strips of AA6082 alloy and S355 steel, each with a thickness of t =8mm, are welded to the adapter in the same way. Since the explosion-welded adapters are joined to the respective assemblies in shipyards using Gas metal arc welding (GMAW). Thus, GMAW is applied to produce tensile specimens. Figure 3 shows an example of the laser-welded adapters. The laser-welded adapter piece is to be used as a prefabricated connecting piece between the steel hull and the aluminum alloy superstructure.

Figure 3. Laser-welded adapter sections for tensile testing.