Numerical simulation of a three-pass TIG welding using finite element method with validation from measurements

Structural integrity assessment of welded joints requires characterising the residual stresses generated during the process. Although measurements can provide a quantitative estimation of the residual stresses, a reliable numerical model offers greater advantages in terms of cost, time and versatility. A validated model can be used to optimise the measurement procedure and thereby aiding in further refinement of the model itself. In the current work, a three-pass tungsten-inert gas welding in an austenitic stainless-steel plate is simulated using a three-dimensional sequentially coupled thermo-mechanical analysis for the purpose of predicting the transient thermal profiles and the final residual stresses as a part of NeT programme. Block-dumped heat transfer analysis was conducted with element activation and deactivation to represent the physical deposition of the weld beads for each pass, followed by a mechanical analysis to predict the stresses. Incremental deep-hole drilling and neutron diffraction techniques at ILL and HZB facilities in Grenoble and Berlin respectively, were employed to measure the residual stresses through the thickness of the sample plate at the center. The predicted thermal history and the residual stresses are verified with the measured thermocouple recordings and the stresses respectively.