Field Assisted Sintering Technology (FAST) or Spark Plasma Sintering (SPS) with a post-sinter forging process

FAST-forge is a novel cost-effective processing route for consolidating titanium alloy powders into near net shape components with wrought properties in two steps.

We have currently demonstrated such a route at the laboratory scale; using field assisted sintering technology (FAST) to produce a shaped preform billet that is finished to near net shape using a one-step forging operation. The geometries and microstructures produced via FAST in isolation are not those typically required for finished components and we therefore see FAST as an intermediate step in this route; a subsequent one-step hot forging operation will provide near net shape parts with a refined microstructure.

Current investigations have created simple shaped FAST specimens from Ti-6Al-4V hydride-dehydride powder, which were fully dense and microstructurally homogeneous. Analysing the microstructural evolution of these samples under varying thermomechanical processing parameters will allow development of simple microstructural prediction models. Linking these models with finite element simulation will allow iteration towards more complex optimised shape preform billets that, after forging, give the required properties with minimal material wastage, with the further possibility of giving tailored microstructures at specific locations within a component.

Additional work is looking at tailoring the FAST-forge route to specific alloy chemistries, including Ti-5553 for aircraft landing gear applications and alloys derived from synthetic rutile produced via the Metalysis FFC process.

We believe FAST-forge, when combined with feedstock powder from a lower-cost alternative extraction method, could become a disruptive technology that will enable a step-change in the economics of titanium components.

Comparison of conventional titanium forging production route and proposed FAST-forge route.

Comparison of conventional titanium forging production route and proposed FAST-forge route.

DEFORM™ FEM simulation of a conventional rocker arm forging using material data generated from a FAST produced Ti-6Al-4V billet by the STAR group