Numerical Analysis of Process Dynamics in Laser Welding of Al and Cu

The process windows for welding Al and Cu are quite limited due to process instabilities like spiking or humping that lead to severe welding failures. Within this paper the fluiddynamical reasons for these instabilities will be analysed by means of multiphysical numerical simulations of the laser beam welding process. After a short introduction into the process model, the simulation results will be verified on basis of experimental results. Then we will focus on the analysis of the different process dynamics during welding for both Al and Cu. The reasons for the humping and spiking instabilities will be revealed. Finally an outlook on current developments, e.g. concerning the grain growth during solidification, will be given.