Analysis of circumferential CO2 arc welding welded shield machine hob to investigate the welding residual stress fields

This paper investigates the distribution and formation rules of welding residual stress during the process of shield machine hob welding using CO2 arc welding. A corresponding three-dimensional digital model is created using the FEA software to research the distribution of welding residual stress during the single pass wire filling welding. The numerical model of a shield machine hob is verified by the welding experiments. This study utilizes numerical computational methods to describe the causes and changes of welding residual stress and strain during the welding process. According to the calculations, the results indicate that compressive axial residual stress is observed on the outer surface of the hob body near the weld line. Conversely, tensile axial residual stress is evident on the inner surface in contrast. Additionally, both the outer and inner surfaces of the hob body exhibit tensile hoop residual stress. Near the weld line, the upper surface of the hob ring shows tensile transversal and longitudinal residual stresses. The main reason for this phenomenon is that different plastic strains are generated because of the thermal contracting deformation at the various surfaces and internal stress self-balance. Moreover, the internal residual stress distribution of fillet weld is investigated, which is obviously different from the external of fillet weld.