Simulationsunterstützte Erstellung eines erweiterten Prozessmodells für das Unterpulverschweißen durch Kombination indirekter und direkter Erfassung von Schweißbadgeometrie und -dynamik
Final Report Abstract
The aim of this project was to create а mathematical model for the numerical simulation of the submerged arc welding process through direct and indirect acquisition of the geometry and dynamics of molten pools. The work on this project consisted of two parts: experimental and theoretical. In the experimental part, parameters of the welded seam geometry were gathered, depending on the arc voltage, welding current and welding speed. Research on the arc zone under the gumboil were performed, with help of X-ray. This research consists in obtaining experimental data, not only for the output of cross sections of welded seams, but also for their longitudinal sections. In the second theoretical part of this project, the mathematical model of SAW was developed. This model is based on the description of physical processes such as heat and mass transfer, electromagnetic and hydrodynamic processes which occur during the weld seam formation. This model was verified with the obtained experimental data. With the help of the developed model, calculations were carried out. These calculations help to obtain information on the influence of the welding input parameters on the conditions of the welding joint formation. On the basis of computing experiments, it was shown that the nature of the weld bead formation during SAW is mainly defined by the welding current density on a consumable electrode. It is shown that the weld bead formation is mainly defined by the nature of welded plate melting, electrode heating and droplets transfer mode, the size of welding pool free surface deformation, the hydrodynamics and the heat-mass transfer processes as a result of the thermo gravitational, thermo capillary, electromagnetic and forced convection forces. The developed model will form a base for the further development of the modeling of welding processes using other welded materials, welded joint geometries, calculations of chemical composition, microstructural changes, welding tension and deformation formations, assessments of the risk of hot and cold crack formations in welding, corrosion cracking of a welded seam and a heat thermal affected zone, considering different variations of submerged arc welding processes (multi-pass welding, multi wires and et.).
