A model of gas metal arc welding was developed that solves the magneto-hydrodynamic equations for the flow and temperature fields of the molten electrode and the plasma simultaneously, to form a fully coupled model. A commercial finite element code was extended to include the effects of radiation, Lorentz forces, Joule heating and thermo-electric effects. The model predicts the shape of the free surfaces fo the molten metal as the droplets form, detach, and merge with the weld pool. It also predicts the flow, temperature, and electric field. Material properties and the welding parameters are the input variables in the model. The geometry of the numerical model was constructed to fit an experimental apparatus using an aluminum electrode and an argon shielding gas. Droplet frequency measurements were used to verify the model's predictions. For a typical arc, the temperature of the plasma can range up to 20,000 K where there is more uncertainty in the thermophysical properties of the plasma, and the properties in this range are highly nonlinear. For this range, the material properties of the model were adjusted to get a better fit between the numerical and the experimental results. The model and experimental results were comparable.
Citation: Science and Technology of Welding and Joining
Pub Type: Journals
arc, droplet, FEM, GMAW, model