Surface microtexturing of Ti-6Al-4V and SS316L alloys using high pulsed fiber lasers for improving the adhesive bonded performance

Abstract

This study presented the high pulsed fiber laser texturing on Ti-6Al-4V and SS316L alloy substrates to enhance their adhesive bonding strength of heterogeneous materials for the industrial applications. Optical spectrum, surface morphology, cross-sectional profile, surface roughness, and water contact angle (WCA) of laser-textured alloy surfaces were measured using a spectrophotometer, a confocal laser scanning microscope, and a contact angle analyzer. Moreover, the shear strength of adhesive bonding laser-textured Ti-6Al-4V and SS316L alloy joints was tested using a universal testing machine. Before laser texturing, the optical absorbance of Ti-6Al-4V substrates was slight high than that of SS316L ones at the 1064 nm fiber laser waveband. The laser-textured Ti-6Al-4V alloy substrates had varied coloring and significant microstructures compared with laser-textured SUS316 ones. The minimum WCAs of laser-textured Ti-6Al-4V and SS316L alloy substrates were 17.8 ± 1.5° and 25.2 ± 2.9° as the laser average power and scanning speed were 13.1 W and 300 mm/s and 5.1 W and 100 mm/s, respectively. Furthermore, the maximum fracture load of adhesive-bonded laser-textured Ti-6Al-4V and SS316L alloy joints with minimum WCA surfaces was three times more than that of ones with un-textured surfaces.