Preparing a Solid Filament for Use in Additive Manufacturing of Metals

Abstract

Additive manufacturing (AM) or three-dimensional (3D) printing has now become one of the significant green manufacturing methods for use in many sectors of industry. Among numerous additive manufacturing methods that can produce geometrically complex components by adding material in consecutive layers, the most prevalent 3D printing method uses polymeric filaments as feedstock. Meanwhile, metal additive manufacturing requires complex technologies such as selective laser melting of the powder, being the most common metal 3D printing today. This study deals with the development of a metallic filament for use in a novel metal AM process, and the advantages of applying metal wires as a 3D printer input material. The aim is to describe how to achieve a readily printable metal filament that could be used in desktop metal printers. An investigation was conducted on the raw material preparation, design considerations, and microstructural evolution. However, it is very difficult to control such deposition of molten metal in a layer-wise manner. Extrusion of metal alloys in semisolid state is a good candidate process that could provide good deposition characteristics for metal wires. The results of this work show that semisolid deposition of a metal wire represents an affordable additive manufacturing technique. This study illustrates that, by designing an effective thermomechanical procedure, metallic filaments with the desired extrudability could be produced. The effect of process control on the rheological properties of the filament was also investigated. Finally, the desired filament microstructure was characterized to ensure a successful deposition process. The study of the mechanical properties of the filament and deposited beads yielded the desirable values, in turn confirming the success of the process to build a fully dense metallic part.