Influence of the Layer Directions on the Properties of 316L Stainless Steel Parts Fabricated through Fused Deposition of Metals

Abstract

Metal specimens were fabricated via the fused deposition of metals (FDMet) technique with a filament composed of the 316L stainless steel particles and an organic binder. This process was adopted due to its potential as a low-cost additive manufacturing process. The objective of this study is to investigate the influence of the processing conditions—layer directions and layer thicknesses—on the mechanical and shrinkage properties of the metal components. The specimens were printed in three different layer directions. The highest ultimate strength of 453 MPa and strain at break of 48% were obtained in the specimen printed with the layer direction perpendicular to the tensile direction. On the other hand, the specimen printed in the layer direction parallel to the tensile direction exhibited poor mechanical properties. The reason for the anisotropy of the properties was investigated through systematic SEM observations. The observations revealed the presence of segregated binder domains in the filaments. It was deduced that the binder domain was oriented in the direction perpendicular to that of the layer and remained as oriented voids even after sintering. The voids oriented perpendicular to the tensile direction act as defects that could cause stress concentration, thus resulting in poor mechanical properties.

Hybrid Metal/Polymer Filaments for Fused Filament Fabrication (FFF) to Print Metal Parts

“…The anisotropic behavior is controlled by the effect of gravity on the metal part during the sintering process. Kurose et al [8] reported linear shrinkage values which varied with the building orientation between 14% and 23%. Gong et al [9] reported similar shrinkage values but they also noted that features at a lower height shrank less than the same feature at a higher height.…”

“…Kurose et al [8] studied the effects of different building orientations for 316L printed parts using their own filament. All the parts were printed with a rectilinear infill pattern and at 100% infill density varying the layer thickness.…”

Influence of the Infill Orientation on the Properties of Zirconia Parts Produced by Fused Filament Fabrication

“…In FFF and the other MEX techniques [ 8 , 14 , 31 , 32 , 33 , 34 , 35 , 36 ], the generation of the shape by the extrusion of material strands, known as roads, can result in defects in the gaps between the strands or weak areas if the bonding between the strands is not sufficient [ 8 ]. In early investigations, different solutions were proposed to reduce these defects [ 8 , 10 , 37 ].…”

Effect of Layer Directions on Internal Structures and Tensile Properties of 17-4PH Stainless Steel Parts Fabricated by Fused Deposition of Metals

“…Table 2 shows the dimensional shrinkage values of the as-sintered and as-aged specimens. Anisotropic shrinkage after sintering has been reported in previous studies of FDMet-fabricated parts [ 23 , 24 , 25 ]. The binder domains were oriented perpendicular to the layer direction and were both thin and thick in the green parts.…”

“…The filaments were input to a modified commercial FDM 3D printer (L-DEVO M2030TP, Fusion Technology Co., Tokyo, Japan) [ 23 ]. Because the produced filament was too brittle for printing at room temperature, a temperature-controlled chamber for the filament was prepared, and a flexible duct was connected from the chamber to the extruder unit of the 3D printer.…”