[SY-M2] Assessment of residual stresses in welds made of multiphase alloys
Welding can induce strong changes in the parent metal so that the mechanical behavior of a welded structure often remains unclear. Mechanical tests are therefore directly performed on welds to assess the mechanical performance of a welded structure. The purpose of such mechanical tests consists in showing evidences of safety margins. In the future, the growing knowledge on the physics of welding accompanied with better welding monitoring tools may replace the need for such tests. Such developments need enhanced multiphysics and multiscale models validated against experimental measurements. Nevertheless, the complexity of such models is highly increased in the case of multiphase materials
The present work introduces a modelling framework accounting for coupled phase transformations and stresses. The modelling framework is weakly coupled with temperature which is introduced as an external parameter in the simulations. The mechanical behavior features an homogenization scheme, chosen as the β-rule, which accounts for the multiphase nature of the material. The mechanical behavior of each phase accounts for viscoplasticity. Finally, plasticity is coupled with phase transformation to account for dislocation inheritance. The model is then calibrated on a two-phase α-β titanium alloy, namely Ti-6Al-4V.
Finite element simulations of welding are then performed. Such simulations are compared with characterizations of residual stress fields obtained from X-ray diffraction experiments, which have been performed recently at the European Synchrontron Radiation Facility. The qualitative comparison between the experimental characterization and the numerical results is quite good as well as the quantitave comparison of stress extrema. A more detailed comparison is then made including a comprehensive parameter analysis. Finally, the discussion will underline the main role of the β-rule homogenization method on the assessment of residual stresses.
The present work introduces a modelling framework accounting for coupled phase transformations and stresses. The modelling framework is weakly coupled with temperature which is introduced as an external parameter in the simulations. The mechanical behavior features an homogenization scheme, chosen as the β-rule, which accounts for the multiphase nature of the material. The mechanical behavior of each phase accounts for viscoplasticity. Finally, plasticity is coupled with phase transformation to account for dislocation inheritance. The model is then calibrated on a two-phase α-β titanium alloy, namely Ti-6Al-4V.
Finite element simulations of welding are then performed. Such simulations are compared with characterizations of residual stress fields obtained from X-ray diffraction experiments, which have been performed recently at the European Synchrontron Radiation Facility. The qualitative comparison between the experimental characterization and the numerical results is quite good as well as the quantitave comparison of stress extrema. A more detailed comparison is then made including a comprehensive parameter analysis. Finally, the discussion will underline the main role of the β-rule homogenization method on the assessment of residual stresses.