In Situ Cleaning of Bead Surfaces by Utilizing Continuous High-Power Laser Scanning.

In situ cleaning of the weld area on a substrate or weld beads is performed by adjusting power and the laser scanning speed using a conventional continuous high-power laser typically employed for welding or deposition. This process facilitates the removal of contaminants (e.g., oil residues, metal oxides, and post-weld black ash) and enables efficient planning and execution of the welding process. The influence of varying laser scanning power on the cleaning efficacy of a 6061 aluminum alloy substrate was examined. The findings revealed that, as the laser scanning power increased from 1200 W to 3900 W, the cleaning effectiveness on the aluminum alloy surface initially improved and then diminished. At lower laser scanning power levels, the energy was insufficient to evaporate and disintegrate the surface contaminants, whereas excessively high laser power tended to cause secondary burns and oxidation on the material surface. Additionally, excessively high laser scanning speeds reduced the overlap of the scanning area, thereby compromising the cleaning results. The proposed surface cleaning method, utilizing a standard continuous high-power laser, demonstrated satisfactory cleaning performance through visual inspection, oxide detection, and analysis of porosity defects in the weld beads produced post-cleaning. Pre-laser scanning and cleaning significantly reduced the incidence of porosity and enhanced weld quality. This method eliminates the need for a specialized laser cleaning system powered by short-pulse lasers and can serve as a supplementary approach to conventional cleaning methods or in situations where alternative methods are unavailable. Oscillating laser scanning can also be applied to clean curved weld surfaces, effectively removing contaminants and oxides from the deposited weld surface, which is particularly beneficial for multi-layer, multi-pass welding or additive manufacturing processes.