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- Influence of Continuous Laser Beam Welding Parameters on Welding Quality of a Structural SteelPublication . Coelho, Gonçalo; Trindade, Adelino; Guimarães, AndréThis study investigates how key laser welding parameters affect keyhole welding under continuous wave conditions. In particular, the relationship between laser power and focal position, and their interaction with other process variables, plays a critical role in achieving optimal thermal cycles and temperature distribution in the weld seam and heat-affected zone. The study also compares theoretical temperature distributions with experimental measurements to validate the applied thermal models. Weld bead characteristics were evaluated by analyzing the surface finish of the top and bottom sides of the weld. Weld quality was assessed through tensile testing, thermal analysis, and microstructural evaluation. The results demonstrate that slight variations in focal height and power significantly affect the dynamics and geometry of the weld pool. Although negative focal heights improved penetration, they also increased porosity, spatter, and oxidation due to excessive gas formation. Despite these challenges, all samples achieved full penetration, with tensile fractures occurring outside the fusion zone. The study also shows that the focal position relative to the material surface influences energy distribution, molten metal flow, and spatter formation. These factors affect how molten metal moves inside the keyhole and reaches the bottom surface of the weld bead, helping prevent gas entrapment. The findings highlight the importance of parameter optimization in balancing penetration depth and surface quality. Future research should explore real-time monitoring, computational modeling, and alternative shielding gas configurations to improve welding performance.