Duplex stainless steels are characterized by a microstructure containing a balanced ratio of ferrite and austenite. This yields excellent corrosion resistance and mechanical properties. Therefore, these alloys are attractive candidates for the application in safety critical areas as piping, chemical industry or marine infrastructure. The mechanical and electrochemical properties highly depend on the content of the respective microstructural constituents. This can significantly vary during welding or additive manufacturing due to the intrinsic solidification conditions. In order to work towards a wide-spread applicability of additively manufactured components and their use in large-scaled assemblies, comprehensive research on the structural integrity of dissimilar, i.e., comprising additively and conventionally manufactured, weldments is required. Therefore, the current study focuses on the monotonic and cyclic mechanical properties of gas tungsten arc welded joints of directed energy deposited and as-rolled standard duplex stainless steel. The fatigue resistance is examined in total strain-controlled tests and discussed in the context of the unwelded base material as well as similar weldments of as-rolled sheets. The differences in low-cycle fatigue performance were rationalized based on the evaluation of the cyclic deformation response, the corresponding cyclic stress-strain hysteresis and subsequent fractographic analysis. The results were correlated to the microstructure and inherent defects as determined by optical and scanning electron microscopy as well as computed tomography.