Effect of surface morphology of Ti6Al4V alloy parts manufactured by electron beam powder bed fusion on bonding strength of adhesive joints

Abstract

Many applications of Ti6Al4V parts manufactured by electron powder bed fusion (EBPBF) require the parts to adhesively bond to other parts. Thus, how the surface morphology affects bond strength has been studied using an adhesive epoxy. Samples include polished (P) surface, top/horizontal as-built (H) surface and side/vertical as-built surfaces which included nonmeshed (V), nonmeshed plus anodised (VA), and trabecular meshed (M) surfaces. Bond strength between epoxy and EBPBF Ti6Al4V increased in order: P, M, H, V, and then VA surfaces. Good strength in V samples was predominantly contributed by the mechanical effect through micro-interlocking in the partially melted powder. A further increase in bond strength has been obtained through anodising (VA samples), due to the adhesive having infused into the ultrafine and nano-pores. Finally, it has been found that a good interlocking effect but a strength reduction of porous Ti6Al4V have resulted in a strength level being relatively low in M samples.

Keywords

• Surface roughness
• Surface treatment
• Adhesive and AM Ti6Al4V interlocking