Effect of groove configuration on mechanical properties and fracture behavior of 6061 Al alloy and CFRTP laser joint

Laser surface texturing is generally a promising approach to enhance the adhesion property of metal-thermoplastic hybrid structure, and the effect is related to the groove configuration. Laser joining of carbon fiber reinforced thermoplastic composite (CFRTP) to 6061 Al alloy under various groove configuration was carried out, aimed to investigate the effect of groove width and depth on interfacial morphology, mechanical properties and fracture behavior of CFRTP/ Al joints. The tensile-shear force was tested, and the fracture surface and interface morphology were observed by scanning electron microscopy. Besides, the numerical simulation of temperature field was conducted to reveal the joining mechanism. The results indicate that the tensile shear strength of CFRTP/ Al joint gradually increases with the increase of groove width and reaches the peak value of 22.8 MPa when the width is 0.5 mm, then it decreases as the groove width is further increased. Compared to groove width, the tensile shear strength of CFRTP/ Al joint presents similar variation trend with the increasing groove depth on Al alloy surface. When the groove depth reaches 0.6 mm, the maximum joint strength is 24.33MPa. After laser textured Al alloy, the surface fracture mode of CFRTP/Al laser joint features mixed fracture mode including cohesive fracture and interface fracture. This study provides a deeper understanding of the effect of groove configuration on the laser joining of CFRTP/ Al hybrid structure and potentially lays a foundation for the adjustment of suitable groove configuration toward obtaining the desired effect.