Laser joining of titanium alloy to polyamide: influence of process parameters on the joint strength and quality

Laser-assisted metal–polymer joining (LAMP) is a novel assembly process for the development ofminiaturized joints in hybrid lightweight products. This work adopts a design of experiments (DoE) approach to investigate the influence of several laser welding parameters on the strength and quality of titanium alloy (Ti-6Al-4V)–polyamide (PA6.6) assembly. Significant param- eters were highlighted using the Plackett Burmann design, and process window was outlined using the Response Surface Method (RSM). A statistically reliable mathematical model was generated to describe the relation between highlighted welding param- eters and joint strength. The analysis ofvariance (ANOVA) method was implemented to identify significant parametric interac- tions. Results show the prominence offocal position and laser power, as well as significant interaction between laser power and beam speed, on the joint strength. The evolution ofweld defects (bubbles, excessive penetration, flashing, titaniumcoloring, weld pool cavities, and welding-induced deflection) along the process windowwas investigated using optical microscopy. The resulted deflection in titaniumwas quantified, and its relationship with welding parameters was mathematically modeled. Robust process window was outlined to maintain insignificant deflection in the welded joints. Results showed that the growth ofweld defects correlates with a decline in joint strength. Optimal parameters demonstrated a defect-free joint, maximizing joint strength.