Laser-Based Powder Bed Fusion of Ti-6Al-4V Structures with Different Surface-Area-to-Volume Ratios in Oxygen-Reduced and Oxygen-Free En-vironment
5. Symposium Materialtechnik
Clausthaler Zentrum für Materialtechnik
Titanium alloys, such as Ti-6Al-4V, are particularly susceptible to oxidation, which is why their processing in the laser-based powder bed fusion process is carried out con-ventionally in a protective gas atmosphere. However, this atmosphere still contains critical residual oxygen levels, which are to be eliminated as part of a new approach. This approach envisages doping the argon protective gas atmosphere with small amounts of the highly reactive gas silane (ratio < 1:1000). The residual oxygen con-tent is particularly critical in filigree and thin-walled structures that have a high sur-face-area-to-volume ratio and are a typical field of application for this additive manu-facturing process. Therefore, this work focuses on the manufacturing of Ti-6Al-4V structures with different surface-area-to-volume ratios in conventional argon (< 200 ppm residual oxygen) and argon-silane atmospheres (< 10-14 ppm residual oxygen) on an innovative laboratory machine. After processing, the specimens are analyzed for surface topography, microstructure, and Vickers hardness. In addition, energy-dispersive X-ray spectroscopy and X-ray diffraction measurements are carried out to further investigate the chemical composition and present phases in the as-built speci-mens. The influence of the different atmospheres and their residual oxygen content, the surface-to-volume ratio, and possible interactions between them are discussed.