Influence of Laser Beam Intensity Distribution on Keyhole Geometry and Process Stability Using Green Laser Radiation

Laser beam welding is being more frequently employed to join copper materials. The use of green laser radiation shows the advantage of significantly higher absorptivity for these metals compared to near-infrared radiation. Therefore, a change in process stability and defect formation is expected. In addition, the effect of modifying the intensity distribution on the formation of weld seam defects and the geometric properties of the seam in deep penetration mode is largely unexplored. Thus, the aim of this work is the characterization of process dynamics and defect formation in correlation to the focal position and the intensity distribution by means of high-speed imaging and metallographic analysis. A significant reduction of seam imperfections is observed for a gaussian beam profile compared to a Top Hat intensity distribution. An advantageous seam shape and the earlier onset of the deep penetration welding process are favorable reasons for the application of this intensity distribution, while medium to high processing speeds further improve the processing quality.