Progress in laser-assisted hybrid joining technology of titanium (Ti6Al4V) and glass-fiber reinforced polyamide (GRPA)

The demand for lightweight, high-strength materials in aerospace and automotive industries has driven interest in hybrid structures combining metals and fiber-reinforced polymers. Titanium alloy Ti6Al4V offers excellent mechanical properties and corrosion resistance, while glass-fiber reinforced polyamide 6.6 (GRPA) provides high specific strength and reduced weight. Effectively joining these dissimilar materials remains a key engineering challenge due to differences in their thermal and mechanical behavior. This study investigates a laser-based thermomechanical joining process under static conditions to produce Ti6Al4V-GRPA hybrid components. GRPA, as a fiber-reinforced composite, combines the lightweight properties of polyamide 6.6 with the mechanical strength provided by glass fibers, making it ideal for high-performance applications. The process parameters, i.e., laser power, laser-metal interaction time, and texture of the metal surface, were optimized using a full factorial experimental method, and shear tests were carried out to mechanically characterize the hybrid joints obtained. Cross sections were observed with a metallographic microscope, while the fracture shape was also observed with a digital microscope. The quality and performance of the joints were studied to determine the best combination of operational parameters. The results showed the significant influence of all factors investigated (i.e., texture, power, and irradiation time) on the hybrid joints' strength. The ultimate shear force increases proportionally to the joint area as the applied power increases. The best combination enables the realization of a Ti6Al4V-GRPA joint with a maximum shear force of about 5 kN, and a shear strength of ∼10 MPa, achieving ∼23% of the polymer base material's shear strength.