This paper investigates the manipulation of chemical composition of a laser weld by dissimilar filler material and its effect on residual stress. The aim is to minimize residual stresses in the weld seam. In order to negate residual stresses, dissimilar combinations of low-carbon manganese steel (S235JR) base material with high-alloyed solid filler wires (G19 9 and G25 20), as well as similar combinations with low-alloyed solid filler wire G3Si1 are analyzed. The goal of the paper is to show that the so-called low-transformation-temperature effect can be used to induce residual compressive stresses in a weld without the use of specially manufactured filler wires. Chemical compositions are generated within a laser-beam-welding process by means of dilution, proving that the concept of in situ alloying is usable in order to affect the martensite formation on a weld. Dilatometry measurements show that a varying Cr and Ni content in a weld reduces the phase-transformation temperature and increases dilatation. EBSD analysis indicates that a fully martensitic weld with a negligible amount of retained austenite is created while the base material preserves its ferritic-pearlitic microstructure. Residual stress measurements with the hole-drilling method demonstrate a reduction in longitudinal tensile residual stresses, whereby the magnitude of the induced residual compressive stresses depend on the M_s temperature. As a result of this research, it was proven that a reduction in tensile residual stress by means of targeted alloying with conventional materials in low-carbon manganese steel is possible. Under the experimental conditions, residual stress in the weld seam could be reduced to 0 MPa. In some cases, even compressive residual stress in the weld could be achieved.

In the vehicle industry, beam welding methods are successfully applied for the joining of high-quality parts. Here, the focus is mainly put on drive section components. Especially in component manufacturing of couplings, toothed wheel — shaft joints and drive shafts, electron beam welding using small vacuum cycle chambers is applied. The application of powerful solid-state lasers results, however, often in negative consequences, such as soiling by process emissions or increased tendency to spatter. The application of laser beam welding in vacuum allows for the reduction of these side effects and, at the same time, for the increase of penetration depth and weld quality. This article introduces first results gained from tests made with workpieces from the vehicle industry.

In the past few years, the welding of steel with large plate thicknesses has been gaining importance for the structural steelwork engineering. However, it is nowadays performed by a time-consuming conventional submerged arc welding process. A currently developing technique, the laser beam submerged arc hybrid welding process (LB-SAW), combines the high penetration depth of the laser with the high thermal efficiency of the submerged arc process. This paper presents the latest welding results which were performed using the LB-SAW. It was possible to increase the weldable plate thickness up to 50 mm, while simultaneously increasing the process stability. Furthermore, the influence of different process distances on synergy effects was shown.