Experimental and Numerical Comparison of the Effects of Phase Trasformation Changes and Asymmetric Welding on Residual Stresses in Gas Pipe Welding Using LTT Filler

In electric arc welding, the heat generated by the arc causes non-uniform expansion and contraction in the weld and surrounding areas. Uneven expansion and contraction and the resulting plastic deformation are the main sources of residual distortion and stress in welded structures. The distribution of residual stresses in a welded joint depends on factors such as heat input, arc welding speed, material properties, preheating, part thickness, groove geometry and welding execution schedule. In this research, a head to head joint is investigated by penetration welding with experimental methods and finite element simulation. Residual stresses are measured by the central hole drilling method and by converting the obtained data into residual stresses, the obtained results are used to verify the developed finite element model. In the finite element model, the non-coupled thermal-mechanical mode is used and the method of birth and death of the elements is used in the simulation of filler materials. In the simulation, the phase transformation process is considered and with the help of LTT filler introduced, the residual stresses in the single-pass welding show a 15% reduction in the tensile residual stresses. By examining the effect of misaligned welding on the specimens, the amount of residual stresses generated increases significantly.