The residual stress and deformation due to the welding process have significant influences on the service performance of the welded deepwater platform hull. An exact prediction of transient temperature distribution is the important prerequisite to ensure the simulation accuracy of the welding residual stress and deformation fields, especially in the multi-pass welding process. Although the transient temperature distribution and residual stress distribution was studied in the past by various authors, the literature on 3D finite element (FE) simulation of multi-pass welding process is limited. In this paper, a FE model is developed to analyze the transient temperature and residual stress distribution of AH36 steel sheets in multi-pass welding process. A moving heat source model based on Goldak’s double-ellipsoidal heat flux distribution is employed for the heated plates. The addition of the volumetric heat source into the FE model and its movement along the welding pass are realized through a dedicated FORTRAN subroutine. The element birth and death technique in Abaqus/Standard is employed to simulate the weld filler variation with time in welded joints. The transient temperature calculated in the first stage is utilized as the input to the residual stress and distortion due to thermal shrinkage during the welding process and subsequent cooling. The results show good agreements between the temperature distribution and the geometry of weld pool obtained in the present work and those previously reported. Finally, a parametric study is performed to investigate the effect of welding variables, such as geometric parameters of Goldak’s heat source model, welding speed, pre-heat temperature and power input in the multi-pass welds, on the residual stress and distortion of the steel sheets.

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