Influence of the process parameters on the microstructure and the machinability of additively manufactured Ti-5553 titanium alloy

Additive Manufacturing (AM) technologies, particularly laser powder bed fusion (LPBF), are revolutionising the production of complex geometries and lightweight structures. Furthermore, LPBF allows to tailor the microstructure and resulting properties of metallic materials. This study focuses on titanium alloys, crucial for high-performance applications like aircraft components and medical implants. Although AM enables near-net-shape fabrication, many titanium parts still require machining to meet surface and dimensional standards. Titanium's challenging machinability is well-documented for cast and wrought alloys, but only less is known about additively manufactured variants. In this work, the machinability of an additively manufactured Ti-5Al-5V-5Mo-3Cr alloy (Ti-5553) is investigated, focusing on chip formation, cutting forces, and tool wear across different LPBF process parameters. Four LPBF parameter sets were validated, and results were compared to conventional wrought sample. The findings reveal significant variations in machinability linked to LPBF parameters. Specifically, the highest tool loads and wear were observed for samples produced with the highest energy density of E_V = 37.0 J/mm³, likely due to α-phase precipitation. In contrast, samples with lower energy densities (<29.1 J/mm³) exhibited up to 100% longer tool life. Concluding, this study highlights how the machinability of Ti-based components can be significantly influenced by the LPBF processing parameters.