Metal fused filament fabrication of the nickel-base superalloy IN 718

Abstract

This study demonstrates metal fused filament fabrication (MF3) as an alternative additive and highly flexible manufacturing method for free-form fabrication of high-performance alloys. This novel processing, which is similar to Metal injection molding (MIM), enables a significant reduction in manufacturing costs for complex geometries, since expensive machining can be avoided. Utilizing existing equipment and reducing material expense, MF3 can pave the way for new and low-cost applications of IN 718, which were previously limited by high manufacturing costs. Iterative process optimization is used to find the most suitable MF3 process parameters. High relative density above 97% after pressureless sintering can be achieved if temperature profiles and atmospheres are well adjusted for thermal debinding and sintering. In this study, the influence of processing parameters on the resulting microstructure of MF3 IN 718 is investigated. Samples sintered in vacuum show coarse-grained microstructure with an area fraction of 0.36% NbC at grain boundaries. Morphology and composition of formed precipitates are analyzed using transmission electron microscopy and atom probe tomography. The γ/γ″/γ′ phases’ characteristics for IN 718 were identified. Conventional heat treatment is applied for further tailoring of mechanical properties like hardness, toughness and creep behavior. Fabricated samples achieve mechanical properties similar to MIM IN 718 presented in literature. Graphical abstract

Metal Fused Filament Fabrication of AlSi10Mg Aluminum Alloy

“…A particular requirement of high-performance feedstock filaments is that the powder particles must be properly distributed and dispersed throughout the filament [5]. Figure 1a depicts the morphology of the virgin AlSi10Mg powder.…”

“…In this context, Tg was above room temperature; so, to help the adhesion to the printing surface, a bed temperature of 40 °C, which is near the Tg of the blend, was also applied, in addition to the printing parameters mentioned in the previous section. Hence, as the Tm of the used filament is around 150 °C, it is recommended [4][5][6] that a nozzle temperature above the melting point of the binder be used in order to improve adhesion between layers and ensure stability. As seen in Figure 3, using the above-mentioned printing parameters, it was possible to extrude and produce the highly loaded filament, which when printed achieved good adhesion between layers in the printed part.…”

“…For instance, in the work of J. Gonzales-Gutierrez et al [4], MF3 filaments with 55 vol.% of 316L and 17-4PH stainless-steel powders were printed, where the geometry had acceptable GD&T characteristics. In another work, Y. Thompson [5] successfully performed MF3 Inconel 718 parts using a filament containing 55% loading in metal particles.…”

Materials Requirements in Fused Filament Fabrication: A Framework for the Design of Next‐Generation 3D Printable Thermoplastics and Composites

“…[42] Historically, the names "fused deposition of ceramics" (FDC) and "fused deposition of metals" (FDMet) have been very common in the literature regarding FFF, [40] and the term "metal fused filament fabrication" (MFFF, MF3, or MF 3 ) is also gaining popularity to describe FDMet (e.g., refs. [43,44]).…”

Indirect Induction Sintering of Metal Parts Produced through Material Extrusion Additive Manufacturing

“…The subsequent sintering step decomposes the backbone from the debinded geometry and causes the metal particles to fuse, resulting in a densified solid mass (step 3). Representative alloys that have been successfully shaped using FFF and subsequently sintered include stainless steel 17-4 PH [ 31 ], inconel super alloy IN 718 [ 32 ], titanium Ti6Al4V [ 33 ], and copper Cu [ 34 ]. However, conventional sintering is carried out in sophisticated furnaces that can maintain a tailored neutral atmosphere, being out of reach for most users.…”