Effect of post-processing treatments on surface roughness and mechanical properties of laser powder bed fusion of Ti–6Al–4V

Abstract

This study focuses on enhancing the surface characteristics of Ti–6Al–4V alloy fabricated through laser powder bed fusion (LPBF), a prominent additive manufacturing technique. The primary objective is to assess the impact of post-processing surface treatments on the surface roughness, microstructure, and mechanical properties of LPBF Ti–6Al–4V. As-built specimens with fully dense structures underwent sandblasting (SB), chemical etching (CE), and a combination of sandblasting and chemical etching (SB + CE). The investigation reveals significant variation in the surface morphology of as-built samples, primarily influenced by factors such as spattered particles, powder adhesion, and the stair-step effect. In the as-built condition, the down-skin exhibited the highest particle adhesion, covering 11.9 % of the surface. Sandblasting proved particularly effective in removing adhered particles, reducing surface roughness to 5.1 μm from an initial value of 17.8 μm for the down-skin surface. Furthermore, combining sandblasting and chemical etching was more effective than chemical etching alone in achieving uniform surface profiles. Tensile testing indicated that while the ultimate tensile strength remained unchanged, the strain at break significantly improved from 4.8 % to 11.5 %, representing a noticeable increase in ductility in post-processed samples compared to as-built conditions. These findings underscore the influence of post-processing treatments in mitigating surface roughness and enhancing ductility without compromising mechanical strength.