The effect of printing parameters on sintered properties of extrusion-based additively manufactured stainless steel 316L parts

Extrusion-based additive manufacturing (EAM) is a relatively new process developed for the production of complex metallic and ceramic parts needed in smaller quantities. The debinding and sintering step of EAM is adopted from a well-known powder injection molding process. However, the 3D printing step needs special consideration to make EAM competent in the era of rapid manufacturing. This study is intended to investigate the effect of common printing parameters on the microstructure and mechanical properties of sintered stainless steel 316L (SS316L) parts manufactured through the EAM process. Part orientation (Ori), extrusion velocity (V_e), and layer height (h) were changed in experimental runs by following a full factorial design. Extrusion pressure as an indicator of melt stability and a grey relational grade as a combined response of sintered properties were analyzed against varying printing parameters. Physical characteristics measured during debinding and sintering show near isotopic shrinkage and the process is stable. Metallographic characterization in terms of porosity and grain size indicated minor differences when V_e and h were altered. Sintered parts showed improved properties when printed with vertical part orientation and h = 0.5 mm, whereas V_e which contributes significantly to the build-up rate was found to be responsible for melt stability. V_e at 12.5 mm/s exhibited melt stability and higher sintered properties.