Comparative study on interface morphology and tensile property of CFRTP/Ti6Al4V laser joining joint under various groove dimensions

Laser joining merges as a novel technique for the connection of carbon fiber reinforced thermoplastics composite (CFRTP) and metal. Besides, machining grooves on the metal surface presents a surface pre-treating method to enhance the strength of laser joining joint between CFRTP and metal. In this study, the laser joining of CFRTP and Ti6Al4V alloy is performed with different groove dimensions. The effect of groove dimension on interface morphology and failure load is analyzed. In addition, the formation mechanism of the interface and the fracture mode of the joint are further elucidated. The results indicate that the structurally sound connection and maximum failure load are attained with an appropriate groove dimension (groove width: 0.7 mm, groove depth: 0.25 mm, and aspect ratio: 0.36). At a narrower groove, the bubbles inside the resin caused by thermal decomposition of the matrix resin are obtained, while at a deeper groove, the gaps and holes are observed in the interface of the joint, both resulting in a lower failure load.