Vortrag (20 Min., 5 Min. Diskussion, 5 Min. Raumwechsel)
Material extrusion additive manufacturing (MEAM) combined with debinding and sintering presents itself as an economical alternative for the production of parts with complex geometry and short production runs, as opposed to powder bed additive manufacturing technologies that require expensive equipment and materials. In order to use MEAM a feedstock material consisting of a binder system and sinterable powders at high concentrations (> 45 vol.%) are needed. A versatile binder system has been developed that is compatible with steel, titanium, copper, alumina, zirconia, hard metal, and cermet powders. It has been demonstrated that filaments with this special binder and these powder can be used for the fabrication of sintered parts with complex geometry.
In this investigation, filaments with a 55 vol.% of 17-4PH stainless steel have been prepared. Dog-bone specimens have been shaped via MEAM. The majority of the binder was removed by cyclohexane extraction and the debound parts were sintered in a hydrogen atmosphere to obtain dense dog-bone specimens of 17-4PH. The tensile properties of the sintered parts were measured; and the morphology of the sintered and broken parts was studied by means of optical microscopy. The average Young´s modulus was estimated to be 196 ± 21 GPa, the maximum stress was 696 ± 31 MPa and the strain at break of 4 ± 1.12 %, which correspond to 100%, 66% and 16% of the lowest values reported in the literature for 17-4PH casted or shaped by direct metal laser sintering (DMLS). It can be seen that the properties fluctuate significantly depending on the cohesion of the layers of the printed parts. These results indicate that the printed process is crucial and that defects introduced during printing cannot be corrected by sintering.