Elucidating the effect of circular and tailing laser beam shapes on keyhole necking and porosity formation during laser beam welding of aluminum 1060 using a multiphysics computational fluid dynamics approach

In the attempt to produce lighter battery packs at a lower cost, replacing common copper parts with aluminum components has been a popular approach in recent years. With regard to joining technologies, there is a growing interest in applying laser beam welding in battery pack manufacturing due to several advantages such as single-sided and noncontact access while maintaining a narrow heat-affected zone. Motivated by the need to control and reduce weld porosity in AA1060 battery busbar welding with the ultimate goal to enhance durability and reduce electrical resistance, this paper has been developed with the aim to studying the effect of laser beam shaping on porosity formation and, hence, generate knowledge about the underlying physics of the welding process itself. First, a multiphysics computational fluid dynamics model has been developed and calibrated to experimental data; then, the model has been deployed to study the effect of both circular and tailing beam shapes on melt pool dynamics and the evolution of porosity due to the instability of the keyhole. The study elucidated the importance of the keyhole's necking on porosity formation. Findings showed that the tail beam shapes, compared to the circular spot, have a pronounced effect on the reduction of the necking effect of the keyhole-this helps to reduce number of collapsing events of the keyhole itself, thereby leading to the reduction of porosity formation.