Finite element simulation of residual stresses and optimization of welding sequence to minimize distortion in a GMA welded carbon steel T joint

Abstract

It is a well known fact that fusion welding is being extensively used in a wide spectrum of fabrication industries. Keeping in line with this objective, 3D finite element simulation of Gas Metal Arc Welding (GMAW) of a carbon steel T-joint was performed to predict the longitudinal residual stress field in the joint. Besides, the finite element prediction of residual stresses was validated with the residual stresses obtained by the contour method. With the validated 3D finite element model, distortions in the T-joint were computed on the basis of Design of Experiments (DOE), by keeping the GMAW primary process parameters such as welding current, arc voltage and welding speed at various operating levels. A regression model of maximum distortion in the T-joint was then developed, after conducting standard statistical tests to check the adequacy of the regression model in prediction of maximum distortion.. The fillet weld was divided into three step welding sequences on each side of the T-joint for the purpose of optimizing the welding sequence for minimum distortion. Out of all the possible combinations, 2304 sequences were heuristically selected, with the GMAW process conditions maintained at the optimum level. After dividing these 2304 sequences into 6 groups for systematic running of simulations, distortion of T-joint was computed for each welding sequence. An artificial neural network (ANN) model was trained by selecting 50 % of the distortion data obtained by finite element simulation. The minimum distortion predicted by ANN model was found to be in close agreement with that predicted by finite element simulation. It was found that optimization of both the GMAW process parameters and the welding sequence resulted in the overall reduction of the maximum distortion in the T-joint to the extent of 35.86%. This will result in even higher reduction of distortion in the case of relatively larger welded structures newline