Interface behavior and pore distribution of Ti6Al4V/CFRTP joints affected by groove profile

Abstract

This study investigated the effect of groove profile on interface behavior, pore distribution, and bonding mechanism between Ti6Al4V (TC4) and carbon fiber reinforced thermoplastic (CFRTP). Using an ultraviolet picosecond laser system, grooves with varying depth-width ratios (R) and distances between adjacent grooves (T) were precisely etched on the TC4 surface. Experiment results revealed that grooves effectively impede bubble coalescence and growth, reduce pore defects at the grooves’ outer interface, and promote closer bonding between TC4 and CFRTP, thereby enhancing joint strength. In this study, grooves significantly improved joint strength by 40.2 % to 147.5 %, primarily due to increased mechanical interlocking and bonding area. Differences in joint strength among grooved joints are mainly attributed to variations in interface behavior and pore distribution caused by R and T. Appropriate R and T are crucial for inhibiting large-volume pores and reducing pores at the grooves’ outer. When R = 1/5 and T = 360 μm, the joint with small-volume pores, no pores at the grooves' outer, and the lowest porosity exhibits the highest strength (2830.3 N). Grooves showed no significant impact on chemical bonding (CTi0.42V1.58 carburization phase and TiOS). Furthermore, no significant effect of grooves on the chemical bonding (CTi0.42V1.58 carburization phase and TiOS).