Inherent Strain Method for Residual Stress Measurement and Welding Distortion Prediction

Inherent strain method was employed to measure the distribution of three dimensional welding residual stresses in several multi-pass welded joints of thick pipes and thick cladded plates. Since a function expression approach to the distribution of inherent strains was developed, the measuring efficiency for three dimensional internal welding residual stresses in complicated welded joints was improved a lot. The residual stresses measured by inherent strain method were compared with the high cost stress release method and neutron diffraction method. Furthermore, inherent deformation parameters, which are defined by integrated values of inherent strains on transverse sections, were used for the fast prediction of welding distortion in assembling structures. Based the predicted welding distortion, its mitigation methods such as tack welding and jig constraint were discussed.