Exploring Miniaturized HVOF Systems for the Deposition of Ti-6Al-4V

Abstract The exceptional properties of Ti-6Al-4V high strength, lightweight, corrosion resistance and machinability make it one the most widely used alloys in aerospace industry. Significant efforts are underway to establish powder bed additive manufacturing technologies for Ti-6Al-4V. There also increasing attempts use thermal cold spray build near-net-shaped parts with buildup rates orders magnitude higher than bed. Thermal spraying, such as HVOF, can oxidize degrade alloy due processing temperature. Lowering flame temperature through inert gas addition full-size HVOF systems is a possible approach retain solid-state deposition feedstock particles, thereby limiting oxidation detrimental α-case formation, while providing sufficient heat input particle softening plastic deformation at impact. Novel miniaturized systems, jets only few millimeters width, may further offer possibility improve spatial resolution near-net shape forming. process parameter range Ti-6A-4V using liquid-fuelled TAFA Model 825 JP id novel hydrogen-fuelled Spraywerx ID-NOVA MK-6 nitrogen shown. Buildups over 80% efficiency generally yield as-sprayed porosities below 3% hardness above 200 HV 100gf . Attainable microstructures oxygen content function parameters delineated. Recrystallization beta-annealing selected samples lower residual porosity create equiaxed α intergranular ß-phases. Ultimate tensile strengths up 1100 MPa were attained; however, 0.7% was found limit β-phase which contributes limited elongation failure.