Brass represents a large part in the production of components within the copper alloy group. Laser beam welding of this alloy offers great potential for many applications in terms of achievable seam quality and productivity. However, there is a very high tendency of the process to produce irregular seam surfaces, ejection of the molten metal and pore formation. These are due, among other things, to instabilities of the keyhole, which is favored by the evaporation of the alloy component zinc. Furthermore, near-infrared laser beam wavelength can couple poorly into the material due to the low absorption level of brass, whereas absorption jumps during the melt transition. In recent years, high-brilliance near-infrared laser beam sources with adjustable beam profiles have been developed that can lead to keyhole stabilization.
The experimental process investigations are on deep penetration welding of different brass alloys (CuZn37 and CuZn39Pb3). A multi-kW laser beam source with combined core and ring beam is used for this purpose. Main process parameters are identified and systematically varied. The produced seams are analyzed and evaluated using different methods (including micrograph analysis and topography images). The results are correlated with the process parameters. Line Energy per unit length, spot size and process gas supply have a significant effect on the weld seam resulting. Process parameters were found to produce high quality bead on plate and butt welds for sheet thicknesses of 2 mm.