The effect of thermal properties and weld efficiency on residual stresses in welding

A parametric model is adopted and the technique of element “birth and death” is used to estimate the effect of thermal properties and weld efficiency on residual stresses in butt weld joints. Residual stresses and distortions on butt welded joints are numerically evaluated by means of finite element method. The FE analysis allows to highlight and evaluate the stress field and its gradient around the fusion zone of welded joints, higher than any other located in the surrounding area. The main conclusion is the significant effect of varying the value of the conductivity on residual stresses. Several experimental destructive and non destructive techniques for directly measuring residual stress have been developed. However, the application of these methods in practice is usually limited by either cost or accuracy. Numerical simulation based on finite element techniques, therefore, offers a comprehensive solution for the prediction of residual stress and strain as well as welding distortion in complex welded structures. In this study it is shown that the technique of element “birth and death” can be usefully applied to welding process in order to take in account the effect of the thermal properties of materials.