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Ključne besede: PBF-LB/M, IN718, SEM, post-processing-heat treatment, mechanical properties
Objavljeno v DiRROS: 18.06.2025; Ogledov: 70; Prenosov: 30
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Ključne besede: metals and alloys, biomaterials, mechanical alloying, sintering, nanostructure, compression test
Objavljeno v DiRROS: 01.04.2025; Ogledov: 245; Prenosov: 141
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Povzetek: This study explores the mechanical and corrosion properties of yttria-reinforced 316L stainless steel. Powder precursor materials were prepared using mechanical alloying. Varying yttria (Y2O3) contents (1, 3, and 5 wt%) were used to assess its impact on the steel’s properties. X-ray diffraction and scanning electron microscopy confirmed the successful dispersion of Y2O3 within the matrix, with the formation of chromium carbides during spark plasma sintering (SPS). The mechanical properties, including hardness and compressive yield strength, improved with increasing Y2O3 contents, with the highest strength observed in the 316L-5Y2O3 sample. However, corrosion resistance decreased with higher yttria concentrations. The 3 wt% Y2O3 sample exhibited the highest corrosion rate due to localized corrosion in areas enriched with oxide particles and chromium carbides. Electrochemical testing revealed that carbide formation and Cr-depleted regions from SPS processing contributed to the corrosion behaviour. These findings suggest that while yttria reinforcement enhances mechanical strength, optimizing the Y2O3 content and processing methods is crucial to balance both mechanical and corrosion performance in ODS 316L stainless steel.
Ključne besede: mechanical milling, SPS, 316L, austenitic stainless steel, yttria, ODS steel, corrosion, EPR-SL
Objavljeno v DiRROS: 31.01.2025; Ogledov: 311; Prenosov: 192
Celotno besedilo (10,37 MB)
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Povzetek: AISI H13 Is very commonly used in the hot-work category of steels. Whether it is used as a forging die, a hotcutting tool, or a mold in injection molding or die casting, it is always on the table, as the material of choice. However, its potential has not yet been fully realized. New manufacturing techniques such as additive manufacturing (AM) broaden the horizon of the material’s application, and promise improved performance, through optimized geometry, unobtainable by traditional means, and heightened mechanical properties. One of the more widespread AM processes is Powder Bed Fusion (PBF) where a laser or electron beam constructs the model, by meting a thin coating of metal powder applied to a base plate. By repeatedly applying and melting powder, the end result is a layer-by-layer produced part. However, the techniques for producing such parts are not yet refined enough and require further research. Problems like porosities, part deflection, and crack formation due to residual stress are commonplace, while comparably low mechanical properties in the asprocessed state call for post-production treatments. Naturally, every technique has its boons and drawbacks, and that is what this work aims to analyze - How do the PBF parts compare to classically produced ones, and what are the difficulties in producing the later-mentioned parts.
Ključne besede: powder bed fusion, tool steel, additive manufacturing, mechanical properties
Objavljeno v DiRROS: 16.01.2025; Ogledov: 380; Prenosov: 188
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Povzetek: Zinc alloys are recognised for their excellent biocompatibility and favourable corrosion rates, making them suitable for bioabsorbable implants. However, their mechanical properties necessitate improvement to fulfil the rigorous requirements of biomedical applications. This research focuses on engineering pseudo-harmonic structures within zinc alloys through a comprehensive method combining mechanical alloying, spark plasma sintering, and hot extrusion techniques. This fabrication process results in a composite material characterised by a soft core surrounded by a continuous, three-dimensional, ultrafine-grained hard shell. The experiment involved blending pure zinc with Zn–1Mg alloy powder, leading to the formation of both ductile zinc and fine-grained Zn–1Mg regions. While the Mg2Zn11 intermetallic phase was found to enhance the alloy's mechanical strength, the presence of oxide shells adversely affected the material's properties. The elimination of these shells via hot extrusion markedly improved the alloy's tensile strength, reaching an average value of tensile strength of 333 ± 7 MPa. This study provides significant insights into the material engineering of zinc-based alloys for biodegradable implant applications, demonstrating a viable approach to optimising their mechanical performance.
Ključne besede: zinc, magnesium, biodegradable, powder metallurgy, harmonic structure
Objavljeno v DiRROS: 23.07.2024; Ogledov: 613; Prenosov: 415
Celotno besedilo (14,29 MB)
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