Application of low transformation-temperature filler to reduce the residual stresses in welded component

Tensile residual stress is a major issue in integrity of the welded structures. Undesirable tensile residual stress in welding may reduce fracture toughness and fatigue life of welded structures. The low transformation-temperature (LTT) fillers, due to introducing compressive residual stresses caused by prior martensitic transformation, can reduce tensile residual stresses in the weld zone. The effects of using LTT fillers on welding residual stresses of high strength steel sheets are studied and compared with conventional fillers. 3D finite element simulations including coupled thermal-metallurgical-mechanical analyses are developed using SYSWELD software to predict the welding residual stresses. For validation of the finite element model, the residual stresses are measured through hole drilling strain gage method. The results indicate that using the LTT fillers cause a decrease of the longitudinal tensile residual stresses of the weld metal from 554 MPa to 216 MPa in comparison with conventional fillers. The transverse residual stresses of the weld line are changed from tensile 156 MPa to compressive 289 MPa with using LTT fillers instead of conventional fillers

Influence of welding sequence on welding distortions in pipes

This paper presents a three-dimensional thermo-mechanical analysis to investigate the effect of welding sequence on welding deformations in pipe-pipe joints of AISI stainless-steel type. Single-pass TIG welding with V-joint geometry in pipes having a diameter of 274 mm and a thickness of 6.2 mm is studied here. Nine different welding sequences are analysed. The finite element results are compared with experimental data. It has been shown that selecting a suitable welding sequence can substantially decrease the amount of welding distortions in this pipe geometry