The presented work shows the studies in the field of welding metallurgy where laser beam welding (LBW) and friction stir welding (FSW) were chosen to join Mg alloys, Al alloys and high strength steels in similar and dissimilar configurations. A systematic investigation of microstructure formation and its influence on the mechanical properties of the joints was conducted and is presented. The analyses encompass optical microscopy, scanning electron microscopy (SEM), electron backscattered diffraction (EBSD), transmission electron microscopy (TEM), hardness tests, tensile tests, shear tests and residual stress investigations using synchrotron and conventional x-ray diffraction. The obtained results supported the development of LBW and FSW for joining light-weight structures by clarifying the relationship between joint microstructure and mechanical properties. Additionally, the EBSD-based orientation SEM microscopy technique proved to be a powerful tool for assessing welding microstructures, providing both quantitative and qualitative analysis of similar and dissimilar welds produced by fusion (LBW) and solid-state (FSW) joining processes.weiterlesen