Laser cleaning of commercial Al alloy surface for tungsten inert gas welding

Surface preparation is known to have critical effect on welding quality of engineering materials, for instance, oxidation layer may reduce the weld performance significantly due to porosity issue. Laser cleaning is considered as a promising technique to do surface preparation for welding process. This paper presents the effect of laser cleaning on surface preparation for tungsten inert gas (TIG) welding of commercial aluminum alloy. We demonstrated the feasibility of using laser cleaning method to minimize the oxides layer of Al alloy for TIG welding. This one-step process without use of chemicals or any other additives is environmentally friendly. Comparison of the performance between conversional cleaning method and laser cleaning method was examined carefully to identify the changes in microstructure and chemical analysis of Al alloy welds after TIG welding processing. Special attention was paid to porosity distribution in the fusion zone after laser cleaning. In addition, some thermal melting was found to occur and refined microstructure took place between the fusion zone and the substrate after rapid solidification. It is further proposed that laser cleaning can refine microstructure of the interface between filter wire and the substrate during TIG welding, which may play a significant role in affecting the weld quality.