Effect of beam shaping on laser joining of CFRP and Al-Li alloy

Dissimilar joining of CFRP and conventional metal attracts tremendous interest due to the increased usage of CFRP in the aerospace industry. However, until now, laser joining of CFRP to metal is commonly performed with low welding velocity (<20 mm/s), which limits its practical applications due to the low joining efficiency. In this work, both experiments and simulations were conducted. The defect-free CFRP/AA2060 laser joint was achieved with a laser power of 5 kW and a welding velocity of 110 mm/s. Compared with the Gaussian laser beam, a rectangular beam spot was obtained using an integrated mirror in the present study. The rectangular beam spot provided a relatively uniform energy density, thus offering a uniform temperature distribution at the CFRP/AA2060 interface, minimizing the porosity defect as well as exhibiting the high shear force. More importantly, the CFRP/AA2060 joints were achieved over a wide range of joining parameters, indicating superior adaptability of the laser joining CFRP to metals with the rectangular beam spot.