In this study, the mechanical properties of butt-welded thin plates made of S700, S960 and S1100 steels under various heat inputs (HI) are investigated. The gas metal arc welding (GMAW) process with two different levels of HI, and laser welding (LW) are implemented for this purpose. Fully automated welding process is employed to attain high quality and homogeneous weldments. Standard tensile tests of the butt-welded joints, together with micro-hardness measurements are conducted in this study. The microstructure of the heat affected zones (HAZ) of the weldments are closely examined using scanning electron microscopy (SEM). It was observed that while the fracture was occurred at the base materials of all S700 and S1100 weldments, the S960 suffered from failure at the HAZ which resulted in reduction of the joint's strength and ductility. For all the studied steels, it was found that the joint's ductility is highly dependent on HI values over the range of 0.3-1.4 kJ/mm for each welding pass. Though, the S1100 steel showed the best performance under welding HI with a moderate change in its mechanical properties and a stable microstructure after welding compared to S700 and S960.

This study considers the effect of bending loading and the symmetry of joints on the fatigue strength of transverse non‐load carrying attachments. Conventionally, the fatigue strength of a welded joint has been determined without taking these factors into account. Experimental and finite element analyses were carried out and both methods showed that both loading type and symmetry have an influence on the fatigue resistance of a welded joint. Under tensile loading, the fatigue strength of asymmetric T‐joints was higher than that of symmetric X‐joints. Respectively, the fatigue resistance of tested joints improved explicitly when the external loading was bending. The finite element analysis was in good agreement with the test results in the joints subjected to tension but gave very conservative results in the joints subjected to bending.

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Björk, Z. Barsoum (2019). Fatigue strength capacity of load-carrying fillet welds on ultra-high-strength steel plates subjected to out-of-plane bending, Engineering Structures, 196, 109282. The article has been published in its final form at

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Current static design approaches for fillet arc welds made of high or ultra-high strength steel (UHSS) do not differ from design of welds made of conventional steels. However, important issues such as potential softening in heat affected zone (HAZ), strength at fusion lines, optimal reinforcement geometry, load capacity changes due to local bending moment and the effect of post weld treatments on the joint strength require careful consideration in order to ensure optimum performance from these steels. This paper reprises results of previous research works and recent findings, and summarizes key aspects of weld design specific to UHSS welds.

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