Computer modeling of weld joint microstructure and residual stresses

A systematic study of weld joint microstructure and residual stress development has been conducted using computer modeling.; The temperature field was obtained using a 2D thermal model. A prescribed temperature double ellipsoid was employed as the moving heat source in the weld pool to compute the weld joint temperature history. The computed temperature was in good agreement with the existing experimental value.; Weld metal (WM) and heat affected zone (HAZ) microstructure evolution in a low alloy steel weld joint was modeled using algebraic equations for thermodynamics and ordinary differential equations (ODEs) for kinetics based on the weld joint chemical composition, austenite phase grain size and thermal history calculated using the thermal model. A 2D model was used for the calculation of the volume fraction of microstructural constituents.; Modeling of residual stresses in a butt-welded plate and a T-joint was addressed by 3D modeling. The thermal load computed by the thermal model was used to solve the conservation of moment and equilibrium of forces momentum equation, constitutive equation of stress and strain and compatibility equation between strain and displacement for the residual stress and displacement fields. The effects of weld length, weld constraint and welding sequence on residual stresses were also investigated.