Investigation on New Technique of Adjusting Welding Residual Stresses in Butt Joint

The principles of the common techniques for adjusting or relieving of residual stress in welded joints are analyzed in the paper.The authors believe that if the technical measure to reduce the restrained contraction of weld during cooling is taken the extent of the residual stress could be adjusted effectively in actual joint under the condition of no phase transition in base metal taking place.The relation between the longitudinal and transverse residual stress based on the Hook's Law and the principle of volume keeping constant during metal deformation is established (i.e.the value of transverse residual stress may affect that of longitudinal residual stress) and the new explanation for the low temperature stress relieving method is given.The authors have suggested and investigated a new method to adjust and control the transverse residual stress in butt joint based on the viewpoint of reducing the friction between the welding platform and work piece.The results obtained from the experiments showed that both transverse and longitudinal residual stress in butt joint could be decreased evidently after the measure to reduce the friction resistance being taken for Q235 mild carbon steel butt joints with 8 mm thickness.