Surface morphology influences of PBF-LB manufactured Ti6Al4V parts on adhesive bond strength—investigation of as-built and surface-treated conditions

Abstract

Additive manufacturing in combination with adhesive bonding enables high lightweight potential in structural design. A decisive factor for high adhesive bond performance are the surface properties. In the present work, the surface morphology of laser powder bed fusion (PBF-LB) processed Ti6Al4V parts was investigated in the as-built condition for the build orientations 0°, 45°, 90°. Furthermore, subsequent surface treatment by grit blasting or laser treatment allowed to modify the surface morphology and examine its effect on the bond strength. The surface characteristics were assessed using scanning electron microscopy, laser confocal microscopy and contact angle measurements. Evaluating the bond strength was done for tensile loading by centrifugal adhesion testing. The lowest bond strength was found for 0° oriented specimens, while the 45° and 90° oriented samples showed similar strengths. Fracture surface analysis of the as-built surfaces showed that the partially melted particles remain attached and cause mechanical interlocking. Furthermore, surface treatment by grit blasting allowed a minor improvement of the bond strength, while with laser treatment a significant increase was possible.