Mass Finishing of Ti–6Al–4V Additively Manufactured by Laser Metal Deposition with Powder Process

Abstract

The surface finish of parts produced by laser metal deposition using powder (LMD-p) is a major economic factor limiting process acceptance in industry. It notably hampers nondestructive testing, delaying scrap detection. The later typically occurs after costly operations (machining of LMD blank and computed tomography), hence damaging economic competitiveness while severely limiting achievable geometries. This motivates the development of surface post-treatment for additively manufactured metal components. However, the millimeter-scale waviness created by the deposited beads presents an additional challenge for LMD parts compared to powder bed fusion. Although a well-established industrial method, mass finishing (MF) has seen few academic studies. Yet, its ability to attain mirrorlike surfaces is valuable for improving the fatigue strength of alloys sensitive to surface defects, such as Ti–6Al–4V. This work demonstrates the potential of a staged approach in line with industrial practices for the post-treatment of LMD-p mechanical specimens. Effects of polymer and ceramic abrasive media during high-energy centrifugal barrel finishing are compared, each yielding noticeably different surface finish. Additional fatigue tests and X-ray radiography evidence the benefits of MF in terms of mechanical properties and inspection capability. Other post-treatments such as laser or chemical polishing complement this study for comparison and discussion purpose.