D finite element modeling of the thermally induced residual stress in the hybrid aser/arc welding of lap joint

In this study, a three-dimensional (3D)finite elementmodel is developed to investigate thermally induced stress field during hybrid laser–gas tungsten arc welding (GTAW) process. In the hybridwelding case, we focus on the GTAWprocess sharing commonmolten poolwith laser beam and playing an augment role in thehybridweldingsystem.Anexperiment-based thermalanalysis isperformedtoobtain the temperature history, which then is applied to the mechanical (stress) analysis. A modified material model is used to consider the influence of face-to-face contact between the top and bottom metal sheets in the thermomechanical analysis of welding lap joints. Results show that the normal stress components prevail in the weld zone during hybrid welding process, and maximum thermal stress exceeding the yield point of material exists at the heat affected zone (HAZ) near the weld pool. Increasing the welding speed inite element model esidual stress causes the penetration and width of weld bead to decrease, and the thermal stress concentration at the welded joint is also reduced accordingly. After welding and cooling down, longitudinal tensile stress (SZ) and transverse compressive stress (SX) are retained in the formed weld, and the higher longitudinal compressive stress exists around the weld bead. In addition, a series of experiments are performed to validate the numerical results, and a qualitative agreement is achieved. Compared to the welded joint ser w the m obtained by GTAW and la by hybrid laser–GTAW is