Analysis of influence of initial gap of laser-arc hybrid butt welds on inherent strain and welding deformation of a pipe structure

Although the laser-arc hybrid welding process has the advantages of smaller deformation and wide freedoms using different energy ratios, some initial dimension errors such as initial gap or initial mismatch before welding assembly have a significant influence on the final shape of welded structures. In this paper, a thermal elastic-plastic finite element model was developed to investigate the temperature fields and plastic strains in butt joints of steel plates with three different initial gaps (0.2 mm, 0.5 mm, and 1.0 mm). Four inherent deformation parameters, longitudinal inherent shrinkage, transverse inherent shrinkage, longitudinal inherent bending, and transverse inherent bending, were calculated and compared with different initial gaps. Finally, welding deformation in a steel pipe structure with five weld lines was predicted by the inherent strain theory.