Thermometallurgical and mechanical modelling of welding – application to multipass dissimilar metal girth welds

Abstract

The prediction of welding residual stresses and distortions needs to take accurately account of the couplings between heat transfer, metallurgy and stresses–strains. The numerical simulation of multipass welding of dissimiliar metal including ferritic steels is specially difficult as three-dimensional (3D) simulation a priori needs to accurately take into account the complex phenomena in the heat affected zone and in the overlapping regions. The results obtained using a simplified two-dimensional axisymmetric model are discussed according to those resulting from a complete 3D simulation. It is shown that for multipass circular welds, 3D computations are mandatory to analyse overlapping regions but two-dimensional assumptions enable to capture stress distribution in the current region. Comparisons with experimental measurements of stresses using neutron diffraction or deep hole drilling are presented to validate the computed residual stresses.