Influence of process parameters on the joint characteristics during laser joining of aluminium alloy and CFRTP

Fiber laser joining of 6061 aluminium alloy and carbon fiber reinforced thermoplastic composite (CFRTP) was performed in this work. The effect of three process parameters including laser power, traveling speed and defocus distance on the bonding interface and joint properties was investigated. Shear tests were performed to evaluate the joint strength in different variables. X-ray photoelectron spectroscopy (XPS) was adopted to confirm the chemical states of elements at the interface. The results indicated that the shear strength of joints first increased and then decreased with the increase of heat input. Insufficient flow of CFRTP could not fill the grooves of aluminium alloy surface at low heat input. The resin was decomposed at excessisvely high heat input, causing pores remained at the interface. The fracture mode was determined as the interface failure. XPS result revealed that no new chemical bond was found at the interface, and the mechanical interlocking between aluminium alloy and CFRTP was main bonding mechanism. The maximum shear strength was 23.8 MPa, which was obtained as laser power, traveling speed and defocus distance was 1100 W, 5 mm/s and +10 mm, respectively.