EUROPEAN CONGRESS AND EXHIBITION ON ADVANCED MATERIALS AND PROCESSES - EUROMAT 2021

Type 316LN austenitic stainless-steel is a major structural material used in various components of fast breeder reactors. A suitable single pass welding process must be considered that gives better weldability in the fabrication of thick components. In this regard, the activated TIG welding process can weld thick sections by a single pass up to 12 mm. An ideal weldment should be free from residual stress and distortion. In the present study, measured residual stress distribution in Activated TIG-welded SS 316LN weld joints are compared with those estimated by the finite element model (FEM). The modelling objective is to estimate the influence of weld metal volume produced by the pass sequence and hardening model on the welding residual stress distribution. A moving heat source based on Goldak’s double ellipsoid heat distribution model is utilized in the FEM. The model has been developed with a single-pass and double-pass approach. The welding residual stress distribution in the weld joints were calculated using isotropic, kinematic, mixed kinematic-isotropic and ideal plasticity hardening models. The calculated temperature cycles were validated using experimental data and sequentially coupled to mechanical analysis for residual stress and distortion prediction. The computational results show that the weld metal volume significantly influences welding residual stress distribution and distortion. It is preferable to have a narrower weld metal volume either with a single or double pass that eventually provides a lower residual stress distribution and distortion in A-TIG weldments. The numerical residual stress distribution obtained using the isotropic hardening model is in good agreement with the experimentally measured data obtained from X-ray diffraction and ultrasonic LCR based measurements.