Influence of laser parameter on weld bead shape and process stability of laser welded steel sheets

Laser butt-welding of dissimilar heat sensitive materials is one of the most challenging tasks. Significant differences in melting and transition temperatures are typical and occur frequently. Therefore, accurate control of the temperature profile at the interface of the weld is essential. In this paper, the influence of the laser parameter power and velocity, as well as laser spot diameter on the laser process were investigated. It is shown that the beam diameter has a significant impact on the weld bead formation. Further variation of the type of shielding gas showed an effect on the bead geometry depending on the used laser spot diameter. Spectroscopic process observations showed a significant impact of the spot diameter and shielding gas on the energy input and the efficiency of the laser process. A homogeneous damping effect of the laser radiation was obtained by using the larger fiber diameter accompanied with a higher overall intensity of process radiation.