Effect of laser power on laser joining of carbon fiber reinforced plastic to AZ31B Mg alloy

Abstract At present, a reliable and stable laser joining of magnesium alloy and carbon fiber reinforced plastic (CFRP) was difficult to be achieved. The effect of laser power on the performance of the AZ31B/CFRP joints was investigated. The dynamic behavior during the laser joining process was captured by a high-speed camera. The interfacial temperature at the center of the weld was measured. The lap joints by laser joining were fabricated and the fracture surfaces were observed. The chemical bonding at the interface was identified by X-ray photoelectron spectroscopy (XPS). The joining mechanism of the joint with various laser power was clarified. The results showed that the joints were free of the bubbles defects. The shear force of the joint first increased and then decreased as the laser power increased. The maximum shear force was 1714.17 N (about 9 MPa) in the case of 700 W. The interfacial temperature was 390℃. The maximum bonding width of resin and ratio of bonding region to adhesive region were obtained in the case of 700 W, which were 4.45 mm and 88% respectively. The fracture pattern included cohesive fracture and interface fracture. The reinforcing fibers were stretched, indicating the enhancement of the joint strength. A new chemical bonding MgCO3 existed at the interface, further improving the performance of the joint. The proper laser power could achieve an effective joining between AZ31B and CFRP.