Assessing the mechanical properties of out-of-specification additive manufacturing Ti-6Al-4V powder recycled through field-assisted sintering technology (FAST)

Abstract

A gas atomised Ti-6Al-4V powder, classified as out-of-specification for additive manufacturing (AM), was consolidated via Field-Assisted Sintering Technology (FAST). Fully dense 250 mm diameter discs with lamellar or bimodal microstructures were produced by FAST processing either above or below the β-transus temperature. Static and dynamic mechanical properties were assessed by testing full-size specimens in the ‘as-FAST’ condition. Material from both processing conditions exceeded the ASTM Ti-6Al-4V powder metallurgy requirements for yield/tensile strength and elongation. Furthermore, material from the edge of the disc processed below the β-transus temperature meets ASTM requirements for wrought Ti-6Al-4V. Fatigue performance also compared favourably with conventionally processed Ti-6Al-4V. This work establishes that surplus AM powders can be successfully recycled via the one-step FAST process and provides confidence that this ASTM-grade material can be used in a range of applications under both static and dynamic loading, which will improve the sustainability credentials of the AM sector.