The Influence of Key FDM Printing Parameters and Post-Processing on the Porosity, Microstructure and Mechanical Integrity of Ultrafuse® 17-4 PH Stainless Steel Components

Abstract

This study investigates the influence of key printing parameters and post-processing conditions on the printability, microstructure and mechanical integrity of 3D-printed components using an Ultrafuse ® 17-4 PH stainless steel filament and metal Fused Deposition Modeling (FDM). A full-factorial-type of experimental design was implemented, varying layer height, print structure and infill orientation. Specimens were designed based on ASTM D368 type V. Green parts were printed using a Rat Rig V-Core 3 FDM 3D printer as well as evaluated via computed tomography (CT) to analyze and characterize the porosity in the 3D printed parts. The results showed that ‘Only-infill’ printed structures and layer heights of ≤25% of the nozzle diameter led to a significant decrease in average porosity levels with values recorded below 3.8 % (V/V). ‘All-wall’ specimens exhibited a comparatively higher level of porosity attributed to an increased cooling rate-to-deposition time ratio that weakened interlayer bonding and promoted void alignment along bonding lines. Uneven shrinkage, surface bulging and geometric irregularities were evident across the printed samples, primarily resulting from non-uniform binder distribution and inhomogeneous temperature gradients during fabrication. The experimental findings established a strong correlation between printing parameters, microstructural evolution and part densification. These results provide a technical framework for optimizing process parameters to achieve high-density, low-porosity stainless steel components fabricated through metal FDM, thereby enhancing the reliability and performance of additively manufactured metallic parts.