Multi-metal 3D printing with extrusion method

Abstract

3D printing has always been known as one of the most advanced technologies to produce various parts in a wide range of materials. Recently, fabrication of multi material parts has been considered by additive manufacturing technologies. The aim of this work is the feasibility study of manufacturing multi-metal parts by material extrusion technique, deposited from two different metal filaments within a single printing session.

In this master thesis, a brief description of additive manufacturing techniques, their benefits, limitations, and applications were first presented. Then, in experimental work, three stages including printing, de-binding and sintering were studied, and the results compared. According to this, two ferrous alloy filaments i.e. stainless steel 316L and high carbon iron were chosen for printing a couple and a mixed sample. The samples, after de-binding, were isothermally sintered at different target temperatures in the range of 1310-1400 °C for 1h and 6h in argon atmosphere. The sintered samples were cooled down to ambient temperature inside the furnace with slow rate. Finally, sintered density, dimensional changes, and microstructural evolution of the final parts were also investigated.

In conclusion, both couple and mixed types of multi-metal parts were successfully fabricated by fused filament fabrication. The final parts became dense up to 84% and 87% of theoretical density for couple and mixed samples, respectively. Also the amount of shrinkage was around 23% for couple sample, and 12% for mixed sample. Since the surface quality of the sintered samples were not as high as it is acceptable, a post-processing such as machining, sanding or filing is required.