Finite element simulation and measurement of welding residual stresses

Residual strains and stresses in a hollow steel beam that had been welded to a D-shaped cross-section have been simulated by plane deformation finite element models and compared with experimental measurements obtained using the neutron diffraction strain-scanning technique. Neutron strain scanning, in contrast to other experimental techniques, is capable of measuring, accurately, non-destructively and in detail, the internal strain state at selected locations and directions within a component. This makes it a preferred method for validating model calculations of strain and stress distributions in components. In the finite element simulations a plane deformation model incorporating temperature-dependent material properties was adopted. With the assumptions for material properties that were made, the plane deformation model predicts the overall bending of the beam and the overall residual strains and stresses reasonably well. Locally, in the weld metal the predicted residual strains and stresses depend very much on the values of the thermal strain, which in one simulation include volume changes due to solid-state phase transformations. In the other simulation presented here the volume changes due to solid-state phase transformations were not accounted for.