Modeling Heat and Mass Transfer and Fluid Flow in Three-Dimensional Gas Metal Arc Welding

This paper extends a mathematical model and numerical techniques previously developed for simulating stationary 2-D gas metal arc welding (GMAW), to moving 3-D GMAW. The filler droplets carrying mass, momentum, thermal energy, and species periodically impinge onto the weld pool, while moving at a certain speed in the welding direction. The complicated transport phenomena in the weld pool are caused by the combined effect of droplet impingement, gravity, electromagnetic force, plasma arc force, and surface tension force (Marangoni effect). The weld pool shape and the distributions of temperature, species, and velocity in the weld pool are calculated as functions of time. For the first time, the phenomena of “open and close-up” for a crater and the formation of ripples at the surface of a solidified weld bead are predicted by mathematical modeling. Under the welding conditions used in the present study, detailed mechanisms leading to the formation of ripples are discussed.