NanoTi - Grain refinement of Ti-6Al-4V wire to enable Aerospace DED AM

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Airframe fabricators use large machined titanium components but their manufacture methods makes inefficient use of material. Most (typically more than 80%) of the high value, pedigree material purchased to make a part is machined away into low-value swarf, that has to be scrapped, or recycled through energy intensive and environmentally costly processes. The industry uses the term buy-to-fly ratio (BtF) to quantify the mass of material purchased to make the part, compared with the mass of the finished component. For large components of ~25kg a BtF of 5:1 to 10:1 is typical, but for several wide-body structures BtF of \>20:1 are also seen.AM offers a manufacturing route that can be significantly more material efficient with BtF of 3:1, and typically <2:1 with an optimised process.Powder bed Additive Manufacturing is being used effectively for components of up to ~3kg mass, using powder feedstock, but is too slow and limited in dimension (maximum practical dimension is <1m) to be viable for larger components. For larger components, DED (directed energy deposition) is the AM method; whereby wire or powder feedstock is fed into a deposition head, which is manipulated to form the component layer-by-layer. This AM approach is able to address large (e.g. 25+kg) components reducing the metal consumption of the airframe business, and consequently lower costs and environmental impact.From a material stand-point, Ti6Al4V alloy is recognised as the "workhorse" of airframe fabricators, and represents almost half of the market share of titanium products used worldwide. However, Ti6Al4V suffers from inter-pass columnar grain growth when deposited using DED AM -- which severely reduces its mechanical performance.It is well established that small additions of grain growth modifiers can offer such a solution; the issue has been how to make a suitable, low-cost, feedstock material that can deliver this.Epoch Wires has a unique wire production approach, developed for superconducting wire manufacture, that offers a way to finely and reliably offer such a production method.Within the project, we will produce and evaluate a range of doped wires and establish their 'AM-ability" using a full range of DED AM methods (Arc/WAAM, Laser and Electron Beam DED) -- potentially offering the aerospace sector a key input into unlocking the full potential of AM for aircraft manufacture.