Influence of droplets in gas-metal arc welding: new modelling approach, and application to welding of aluminium

A new approach for calculating the influence of droplets on the arc and weld pool in gas metal arc welding is presented. A three-dimensional self-consistent model of the arc, workpiece and electrode that includes the influence of metal vapour is used to track the temperature, velocity and diameter of a droplet as it detaches and passes through the arc. The time averaged influence of the droplet on the arc and weld pool is then calculated. The approach allows very large savings of computational time compared to the usual volume of fluid method. The approach has been applied to one-drop per pulse welding of aluminium. Weld pool depth and shape were predicted accurately. The enthalpy transferred to the weld pool was found to have a strong influence on weld pool depth, while the flow in the weld pool depends on the momentum transferred by the droplet and the magnetic pinch force.