New insights into the effect of tantalum addition on the microstructure and machinability of additively manufactured Ti–6Al–4V

Recently there has been great interest in modifying commercial titanium alloys with additives to overcome certain limitations encountered during additive manufacturing. These near-net shape products usually require machining to ensure that precise tolerances are achieved but the impact of alloy modification to machinability has not yet been thoroughly explored. In this work the influence of tantalum modification of Ti–6Al–4V on the microstructure, properties and machinability of parts produced by Laser Powder Bed Fusion is explored. In particular, prior-β grain size of Ti–6Al–4V was reduced by nearly 50% upon the addition of 10 wt% tantalum. A comparative study was conducted on the machinability of Ti–6Al–4V and Ti–6Al–4V+Ta under slot milling conditions, using the supplier-recommended machining speed of 56 m/min for titanium alloys. This work demonstrates that adding tantalum refines the microstructure, reduces the overall texture by nearly 6 times, and decreases required machining energy by approximately 0.4 J/mm3 compared to Ti–6Al–4V. However, this improvement comes at the cost of accelerated tool wear, resulting in a 30% reduction in tool diameter after machining the same volume of material. This research lays the groundwork for enhancing properties and facilitating easier machining of additively manufactured titanium components.