Welding residual stress analysis of 347H austenitic stainless steel boiler tubes using experimental and numerical approaches

A three-dimensional finite element model that can simulate multiple start/stop welding process of 347H austenitic stainless steel boiler tubes was developed to estimate welding residual stress distributions. Two-dimensional axisymmetric finite element model and threedimensional finite element model that exhibit half symmetry along circumferential direction are also employed for verification purposes. Sequentially coupled thermo-mechanical finite element analyses were carried out using three different models to obtain and compare temperature fields and resulting residual stress fields. In addition, node-based temperature heat input method and element-based body flux heat input method were applied to three-dimensional half symmetry model to review the adequacy of heat input model that can best estimate welding residual stress distribution in the tubes. Finally, welding residual stresses obtained using different models were compared with measured data, and it was observed that results using three-dimensional finite element model that can take into account welding start/stop effects are in good agreement with those of measured data obtained by the X-ray diffraction (XRD) method.