Browsing by Author "Navas-Pinto, Wilson"

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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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    TENSILE/COMPRESSIVE RESPONSE OF 316L STAINLESS STEEL FABRICATED BY ADDITIVE MANUFACTURING
    (2024) Barrionuevo, German Omar; La Fe-Perdomo, Ivan; Caceres-Brito, Esteban; Navas-Pinto, Wilson
    Additive manufacturing has evolved from a rapid prototyping technology to a technology with the ability to produce highly complex parts with superior mechanical properties than those obtained conventionally. The processing of metallic powders by means of a laser makes it possible to process any type of alloy and even metal matrix composites. The present work analyzes the tensile and compressive response of 316L stainless steel processed by laser-based powder bed fusion. The resulting microstructure was evaluated by optical microscopy. Regarding the mechanical proppercentage of elongation before breakage, compressive strength and microhardness were determined. The results show that the microstructure is constituted by stacked micro molten pools, within which cellular sub-grains are formed due to the high thermal gradient and solidification rate. The compressive strength (1511.88 +/- 9.22 MPa) is higher than the tentest, the hardness increased by 23%.