In many industrial applications, such as shipbuilding, crane construction, and pipeline manufacturing, the reliable joining of thick steel plates is essential. Conventional arc welding processes are widely used but generally suffer from long processing times and high thermal loads. In recent years, hybrid laser-arc welding (HLAW) has been introduced as a more efficient alternative. However, welding steel plates especially with thicknesses greater than 15 mm presents several challenges. The weld seam typically consists of an arc-dominated and a laser-dominated zone, leading to limited mixing across the entire seam. This can result in differences in mechanical properties and seam defects.

This study investigates a HLAW process utilizing a 24 kW disk laser beam source with adjustable power distribution between core and ring. The focus is on influencing and enhancing melt mixing through temporal modulation of the laser beam power and suitable power distribution between core and ring fiber. Bead-on-plate welds and butt joints of S355J2+N steel plates up to 22 mm thick are examined. A nickel-containing filler wire is used to analyze element distribution and mixing within the weld seam. Comprehensive process monitoring, including high-speed imaging and thermography, is employed to assess key process characteristics. Metallographic analyses of the weld seams are performed and correlated with measured process parameters. The results show potentials of HLAW using a high-power laser beam source with temporal modulation and adjustable power distribution to improve weld quality and homogeneity.