Non-Destructive Evaluation of Print Quality in Metal Fused Filament Fabrication of 316L and 17-4PH Stainless Steels Using Industrial Computed Tomography

Metal fused filament fabrication is an increasingly accessible additive manufacturing process for metals. However, predicting internal defects that form during printing and post-processing remains a significant challenge. In this study, cylindrical samples were fabricated, debound and sintered using Ultrafuse 316L and Ultrafuse 17-4PH metal filaments. Industrial computed tomography (CT) was used to analyse the samples. Dimensional measurements revealed anisotropic shrinkage: 16% in the crosssectional plane and 18.4% in the build direction. CT analysis identified bonding defects at the shell–infill interface and between adjacent extrusion lines, as well as position-dependent defects that recurred across multiple layers and isolated anomalies within single layers. These findings highlight the value of industrial CT as a powerful non-destructive tool for detecting porosity and defects in metal fused filament fabricated parts.