Hydrodynamic regimes in autogenous fusion welding

  • Author / Creator
    Havrylov, Dmytro
  • The weld bead width and the penetration depth are major parameters that determine the mechanical strength of the weld joint. The analytic models, such as the Gaussian heat source model, may provide quite accurate estimations for the weld width and penetration; however, the model does not account for the weld pool convection which may significantly affect the weld shape. In ``melt-in" mode, the principal driving forces for weld pool convection are buoyancy, electromagnetic forces, surface tension gradients and the arc pressure. The surface tension gradients on the melt surface have been reported in the literature to have the strongest effect on the weld pool convection. This effect is also known as the Marangoni effect. In case of a weld pool, the flow can be directed either outwards or inwards depending on the presence and the amount of surface active elements on the weld pool surface. In this work only the outward convective flows are analyzed. It is proposed that the effect of the Marangoni convection on the weld shape can be formulated in the form of correction factors to the solution for the Gaussian heat source. These correction factors are the objectives of this work. The scaling analysis of the Marangoni convection in weld pools identified five asymptotic hydrodynamic regimes for melts with both high and low Prandtl numbers. Scaling laws for the characteristic velocity of the convection and the Peclet number for the five asymptotic regimes were obtained and calibrated with the auxiliary numerical model and data from the literature. Correction factors for the weld width and depth predicted by the Gaussian heat source were proposed to account for the weld pool convection.

  • Subjects / Keywords
  • Graduation date
    Spring 2021
  • Type of Item
  • Degree
    Doctor of Philosophy
  • DOI
  • License
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