Thermally induced distortion and residual stresses in welded joints

The thermal response of materials to a welding heat source sometimes causes mechanical problems, e.g. residual stresses and distortion and changes in mechanical properties due to changes in the microstructure. Residual stresses and distortions take place in weldments due to local heating and cooling. When this residual stresses combine with the external forces, unexpected failure can be observed during service life of weldments. The distortion can effect the dimensional accuracy of the weldments. Therefore some additional straightening processes are needed after welding process.Prediction of the amount and the distribution of residual stresses and distortion before welding has been an important subject for researchers. In this thesis, SYSWELD finite element package program was used in modelling. The situation of the material after welding can be estimated by modelling, also the optimisation of welding parameters can be done.