Browsing by Author "Mendez, Patricio"

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    Effect of Porosity on Tribological Properties of Medical-Grade 316L Stainless Steel Manufactured by Laser-Based Powder Bed Fusion
    (Multidisciplinary Digital Publishing Institute (MDPI), 2025) Barrionuevo, Germán Omar; Walczak, Magdalena; Mendez, Patricio; La Fé-Perdomo, Iván; Chiluisa-Palomo, Erika; Navas-Pinto, Wilson; Cree, Duncan E.
    The potential of laser-based powder bed fusion (L-PBF) technology for producing functional components relies on its capability of maintaining or even improving the mechanical properties of the processed material. This improvement is associated with the microstructure resulting from the high thermal gradient and fast cooling rate. However, this microstructural advantage may be counterbalanced by the lack of full density, which could be tolerated to a certain degree for applications such as biomedical implants and medical equipment. In this study, medical-grade 316L stainless steel specimens with porosities ranging from 1.7 to 9.1% were additively manufactured by L-PBF using different combinations of laser power and scanning speeds. Tribological properties were evaluated by pin-on-disc testing in dry conditions against a silicon nitride test body and analyzed in the context of microstructural characterization by optical and electron microscopy. The results reveal that higher porosity allows for a diminishing wear rate, which is explained by the capacity of the pores to retain wear debris related with the three-body abrasion. This research provides practical insights into the design of medical wear-resistant components, thereby enhancing our understanding of the potential of L-PBF in the fields of materials science and biomedical engineering.
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    Microstructure effect on sliding wear of 316L stainless steel selectively laser melted
    (2024) Barrionuevo Chiluiza, German Omar; Walczak, Magdalena Marta; Ramos Grez, Jorge; Mendez, Patricio; Debut, Alexis
    Due to varying thermal cycles, the resulting microstructure of metal additive manufacturing differs from the conventionally processed counterpart alloys. Since the mechanical properties depend on the microstructure, the wear resistance of components manufactured by laser powder bed fusion (LPBF) is determined by the processing parameters. This work focuses on microhardness and sliding wear of 316L stainless steel, evaluated nanoindentation and pin-on-disc, respectively, analysed through optical microscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD) and glow discharge emission spectrometry (GDOES). The results show that the LPBF-processed specimens have about 40% higher microhardness and ca. 30% lower wear rate than the wrought counterpart. The enhanced sliding wear resistance is associated with the higher density of dislocations at the cellular subgrain boundaries.