Three-dimensional transient simulation of laser-GMA hybrid welding involving multiple physical
phenomena is conducted neglecting the interaction effect of laser and arc heat sources. To reproduce the
bubble and pore formations in welding process, a new bubble model is suggested and added to the
established laser and arc welding models comprehending VOF, Gaussian laser and arc heat source, recoil
pressure, arc pressure, electromagnetic force, surface tension, multiple reflection and Fresnel reflection
models. Based on the models mentioned above, simulations of laser-GMA hybrid butt welding are carried
out and besides the molten pool flow, top and back bead formations could be observed. In addition, the
laser induced keyhole formation and bubble generation duo to keyhole collapse are investigated. The
bubbles are ejected from the molten pool through its top and bottom regions. However, some of those are
entrapped by solid-liquid interface and remained as pores. Those bubbles and pores are intensively
generated when the absorption of laser power is largely reduced and consequently the full penetration
changes to the partial penetration.