Influence of the layer orientation and the binder system on the mechanical behavior of titanium components manufactured by Metal Fused Filament Fabrication (MF$^3$)

Metal Fused Filament Fabrication offers a simple and cost-effective method to produce titanium components. However, multiple factors, including the binder system, contamination, and print parameters, have a significant impact on the physical and mechanical properties of the final parts. The present study investigates the utilization of the backbone polymers poly(methyl methacrylate) (PMMA) and poly(vinyl butyral) (PVB) in partially water-soluble binder systems. Two distinct debinding strategies were applied with the aim of increasing density while reducing contamination by oxygen and carbon in sintered Ti-6Al-4V components. The specimens were characterized by computed tomography, metallography, scanning electron microscopy, carrier gas hot extraction, and Raman spectroscopy. In addition, the effects of layer orientation and binder system on mechanical performance were evaluated by tensile testing. PMMA-based feedstocks yielded relative densities of 94–95 % combined with comparatively low oxygen and carbon contamination, resulting in ultimate tensile strengths of up to 870 MPa and elongations of up to 11 %. Nevertheless, print-induced defects led to pronounced scatter in the mechanical properties. ... mehrIn contrast, PVB-based systems achieved a high relative density of 98.4 % and an ultimate tensile strength of 900 MPa, but suffered from elevated oxygen and carbon contents, leading to limited ductility (elongation 4.3 %). The utilization of isopropyl alcohol in the debinding process to dissolve the poly(vinyl butyral) resulted in a slightly lower density of 97.5 %, but in excellent ultimate tensile strengths of 890 MPa and elongations up to 13.5 %. No significant differences were observed between the different layer orientations for samples produced with an optimized feedstock and without major print-induced defects. Overall, density, impurity content, and print-related defects were identified as the dominant factors governing the mechanical behavior of MF3-fabricated Ti-6Al-4V components.