<p>Welding thick materials is essential across industries such as shipbuilding, construction, pressure vessels, turbine manufacturing and more. Conventional methods for welding thick metal sections typically rely on arc-based or hybrid laser welding systems, which require significant filler material consumables, multiple welding passes and extensive preparation like beveling. Arc welding processes introduce high levels of heat, leading to structural defects such as plate distortion and a large heat-affected zone (HAZ). In contrast, high-power laser welding offers a solution with minimal HAZ, reduced distortion, and cost-effective, high-quality welds. However, achieving defect-free welds remains challenging due to issues like cracking, bulging and porosity. To address these challenges, Civan’s high-power, single-mode laser systems utilize dynamic beam shaping to control melt pool dynamics and keyhole stability in real-time. By leveraging coherent beam combining and optical phased arrays, new degrees of freedom are introduced—such as beam shape, shape frequency, focus steering, and sequential shaping—far beyond what conventional techniques like diffractive optical elements, beam oscillation, or power modulation can offer. Here, both simulation and experimental results are presented for thick bead-on-plate welding of mild steel using this dynamic beam shaping approach. The findings highlight how different beam shapes and shape sequences influence keyhole stability, melt pool behavior, and the reduction of defects like cracks and pores. Additionally, welded butt joints produced with this method successfully pass mechanical and industry qualification tests, demonstrating the potential for high-quality, reliable welds across a range of materials and applications.</p>