Prediction of arc, weld pool and weld properties with a desktop computer model of metal–inert-gas welding

A three-dimensional computational model of metal–inert-gas welding, which includes the arc, wire and workpiece self-consistently, is presented. It takes into account the phenomena including (1) the motion of the arc relative to the workpiece; (2) the energy, momentum and mass transported by droplets; (3) flow in the weld pool and deformation of its surface; (4) effects of metal vapour and (5) mixing of the wire and workpiece alloys. A graphical user interface has been added. The model predicts the depth and shape of the weld and heat-affected zone and arc and weld pool properties. Thermal histories of the workpiece, required to calculate residual stress and microstructure, are also predicted. Results for welding of aluminium alloy sheets in lap fillet geometry are presented. It is found that the arc temperature is relatively low, due to the high concentration of aluminium vapour, which radiates strongly. The droplets are predicted to mix fairly thoroughly in the weld pool, with the flow in the weld pool driven downwards by the droplet momentum. The orientation of the wire electrode strongly influences the shape and depth of the weld, with a decreased work angle (i.e. further from vertical) leading to a decreased reinforcement height and deeper penetration.