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Direct LaserWelding of an Al-Li Alloy Plate Without Prior Surface Cleaning
K. Chen, W-X. Yang and R-S. Xiao

As we know, the oxide film on the surface of Al-Li alloys has to be cleaned before welding in order to achieve welds without pores. However, doing so is difficult and may result in undesirable pollution with chemical cleaning. In this study as a precondition of laser welding the plate of Al-Li alloy was not treated in any way before welding. A CO2 laser system was employed in the study on porosity control of 1420 Al- Li alloy by dualbeam laser welding. The experimental results show that the influence on the right surface oxide film to the porosity in the weld is bigger than that from the backside when the laser welding is in the form of a beam on the surface of the plate. However, the sensibility of porosity from the backside oxide film has a distinct connection with the formation of an inverse weld when butt-joint laser welding is carried out. Optimized laser welding techniques have been achieved from experiments in order to decrease the porosity in the weld and increase weld quality. The tensile strength of the laser welding joint was also tested in the experiment. The data indicate that the average value of tensile strength about the joints can be up to 336.1 MPa, which is equal to 87.5% of the value of the substrate alloy.

Keywords: Laser welding, Al-Li alloy, dual-beam, porosity, tensile strength

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