Abstract
Increasing the number of process parameters allows a flexible adjustment of the laser+pulsed gas metal arc welding (GMAW) hybrid welding process; however, it places higher demands on the technology development and the process optimization. It is therefore important to conduct fundamental investigations involving mathematical modelling to understanding the hybrid welding process. In this study, thermal action characteristics in laser+pulsed GMAW hybrid welding are considered from the viewpoint of macro heat transfer, and two kinds of adaptive combined volumetric heat source models are developed for numerical analysis of heat flow in the hybrid welding. Based on the appropriate description of heat input from a laser beam, pulsed GMAW and heat content of overheated droplets, the adaptive heat source models are developed for laser+pulsed GMAW hybrid welding through combining three contributions to the heat density, i.e. double elliptic planar distribution of arc heat for both peak and background durations, uniformed distribution of droplet heat content in a double ellipsoid body, and logarithm or parabolic curve-rotated body distribution of laser beam with linearly enhanced peak density along the central axis. The interaction between laser and arc is taken into account indirectly by appropriately varying the distribution parameters of heat sources. The shape and size of the weld pool and the weld reinforcement in the quasi-steady state are calculated for three hybrid welding conditions, which show a fair agreement with the experimental results. The temperature profiles, cooling rates, and widths of the heat-affected zone in hybrid welding under different welding conditions are also computed and compared with those of pulsed GMAW, and the differences among them are discussed and explained.