Experimental evaluation of process-property relationships in bound powder extrusion based metal additive manufacturing

Abstract

Additive manufacturing (AM) techniques permit the fabrication of intricate geometries that are challenging or impossible to produce using traditional subtractive methods (e.g., machining). Bound powder extrusion (BPE), an AM variant, extends this capability to functional metal components in a process akin to the production of polymer parts via consumer-grade printers. AM-fabricated parts differ fundamentally from wrought materials: each exhibits unique characteristics due to inherent defects like porosity, residual stresses, and orientation-dependent mechanical properties stemming from the layer-by layer build process. In BPE, this anisotropy manifests as significant variations in strength and ductility with printing direction, introducing variability and uncertainty that demand thorough characterization for reliable part qualification and engineering deployment. Despite BPE's potential, detailed studies on the mechanical properties of its metal outputs are sparse, with existing data showing inconsistencies from differing processing and testing conditions; even scarcer are systematic explorations of orientation effects essential for design optimization. To address these deficiencies, I undertook a comprehensive evaluation of 17-4PH stainless steel components produced via the Markforged MetalX system, printing specimens in 0°, 45°, and 90° orientations relative to the build direction. These were subjected to tensile testing, hardness measurements, surface roughness profiling, and corrosion assessments, with all metrics benchmarked against wrought 17-4PH. Through these efforts, it was observed that essential, orientation-resolved property insights absent in the literature that will aid in enabling evidence-based design of BPE components, expanded characterizations across Markforged alloys to foster comprehensive material databases, and enable broader utilization in industrial applications.