This paper describes the analysis of thermal and mechanical effects during welding and the following cooling-phase on a welded structure. An off-the-shelf aluminum-profile, as used in other simulation sub-projects of the research center, was chosen as a sample part for the simulation tests. Taking up an important production scenario of lightweight-production, the frontal closing of two profiles is modeled. The development of residual stresses and the distortion is investigated by a thermo-mechanical FE-simulation. The virtually examined process is provided by a hybrid, bifocal laser system consisting of both an Nd:YAG-laser and a high power diode laser (HPDL). For comparison, a single Nd:YAG-process was simulated, too. The theoretically different generation of residual stresses can be verified within the simulation.