2026 GonzalezNino 17 4PH Micromechanical Characterization

Additive manufacturing (AM) technologies, such as laser powder bed fusion (LPBF), allow for rapid fabrication of geometrically complex components that would be difficult to create using traditional casting or subtractive fabrication processes; however, research into AM metals has shown that fabrication defects resulting from LPBF processes (i.e., voids, un-melted particles, etc.) can have deleterious effects on mechanical behavior. Material testing using traditional macro (coupon-scale) volumes may not accurately capture scalable material behavior in LPBF metals, as the distribution of fabrication defects is volume-dependent. To understand fundamental material behavior at scales independent of geometrical fabrication defects (including print-induced material arrangements), in situ micro-mechanical testing of AM LPBF 17-4 PH stainless steel materials is conducted, opening possibilities for future bottom-up material simulation scaling. In this study, the tensile and compressive behavior of LPBF-fabricated 17-4 PH stainless steel is characterized at the micron scale to aid future efforts in the predictive upscaling of structural components, while eliminating void effects and micro-scale print-induced material arrangements in any characterizations. Not surprisingly, behavior comparisons between multiple length scales (micro and macro scales) indicate strength reductions in larger bulk volumes. Micro-tensile measurements resulted in ultimate tensile strength (1359 MPa ± 99.9 MPa standard deviation) and strain before failure (0.31 ± 0.063 µm/µm) values that exceeded those of the macro-tensile specimens (1025 MPa tensile strength and 0.190 µm/µm strain at fracture, respectively).