Application and Modeling of Laser Beam Submerged-Arc Hybrid Process

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In the first phase of the research project, the laser beam submerged arc hybrid welding process has beendeveloped for the CO2-laser as well as the solid-state laser.For both types hybrid welding heads have been realised. In parallel, a model of the hybrid equivalent heatsource has been developed as base for the simulation of the laser beam submerged arc hybrid weldingprocess.With the new orientation towards the use of solid-state lasers, the reproducibility and process stability wasgreatly enhanced. This was mainly because the much shorter laser wavelength is less prone to laser inducedplasma formation that often led to process instabilities with the use of the CO2-laser.With both process variants connections welds with highly acceptable quality have been performed on platethicknesses up to 40 mm. Beside visual testing and assessing the inner weld seam quality, mechanicalproperties have been determined.The gathered results on hardness and tensile strength were in the expected ranges and consistent over thewhole depth of the weld seams, especially between the upper, SA-dominated and the deeper, LB-dominatedareas.The results of the notch impact tests however differed strongly within the weld seam. While the inner,LB-dominated areas give mostly very high values of impact energy, the upper, SA-dominated areas only bearlow impact energy, even lower than the given values for the wire-flux combination.In the third year of the research project, it stand to be explored whether a varation of wire-flux combinations orparameter optimisations can lead to optimised and homogenised values of notch impact energy as well as theother technical properties. In addition, there will be experimental research on the topic of material transportinside of the molten pool. This may lay the foundation on the understanding of the flow conditions inside of thehybrid process zone.