1. Susceptibility of X17CrNi16-2 martensitic stainless steel to hydrogen embrittlement after conventional and deep cryogenic heat treatmentMirjam Bajt Leban, Bojan Zajec, Bojan Podgornik, Črtomir Donik, Patricia Jovičević Klug, Miha Hren, Andraž Legat, 2024, original scientific article Abstract: A low carbon/ high chromium martensitic stainless steel, X17CrNi16-2, was heat treated using two different hardening and tempering regimes (1050 ◦ C/480 ◦ C or 980 ◦C/600 ◦C) — promoting either a high strength or high toughness state, respectively and further combined with deep cryogenic treatment (DCT) at 196 ◦C for 24 h. Over recent years DCT has been recognized as a promising technique to improve the properties of steel, predominantly with respect to its tensile strength, toughness and wear resistance. The influence of DCT on the hydrogen embrittlement resistance of martensitic stainless steel has not yet, however, been reported.
A slow strain rate tensile test (SSRT) with simultaneous cathodic hydrogen charging was selected as the method to assess potential susceptibility to hydrogen embrittlement (HE). Relatively low-intensity hydrogen charging, utilizing a constant current density of 0.1 mA/cm2, in a non-corrosive, slightly alkaline buffer solution, led to a clear reduction in the ultimate tensile stress. This reduction, and therefore the HE susceptibility, was more pronounced in the steel with a higher strength (i.e. that subject to the 1050 ◦C/ 480 ◦C heat treatment condition). Furthermore, DCT did not appear to have any impact on the steel’s mechanical properties in the presence of hydrogen. Fractographic analysis showed clear evidence of HE in the hydrogen-charged specimens.
This paper presents results of the SSRT tests and further fractography results, and discusses the impact of conventional and deep cryogenic treatment on HE susceptibility.
Keywords: martensitic stainless steel, deep cryogenic treatment, hydrogen embrittlement, slow strain rate tensile test
Published in DiRROS: 23.05.2024; Views: 75; Downloads: 75
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2. Effect of microalloying on tempering of Mo-W high thermal conductivity steelJaka Burja, Aleš Nagode, Jože Medved, Tilen Balaško, Klemen Grabnar, 2023, original scientific article Keywords: hot work tool steel, microalloying, močybdenum, tungsten, tempering, heat treatment
Published in DiRROS: 20.05.2024; Views: 69; Downloads: 36
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6. Model uncertainty in a parametric fire curve approach : a stochastic correction factor for the compartment fire load densityFlorian Put, Andrea Lucherini, Bart Merci, Ruben Van Coile, 2024, original scientific article Abstract: A commonly used approach to represent the thermal load in a compartment fire is the Eurocode Parametric Fire Curve (EPFC), which specifies gas temperatures (or rather adiabatic surface temperatures). Recognizing the significant deviations between real fires and the EPFC framework, the concept of model uncertainty is explored. This study does not aim to assess or improve the EPFC, but introduces a model uncertainty, allowing for reliability-based structural fire engineering (SFE). It presents a stochastic correction factor for the fire load density, based on the maximum temperature in steel sections. The focus is on the fire load density, but in general other parameters can be jointly taken into account as well. This correction factor considers protected and un- protected sections, incorporating variations in section factor and protection thickness. The findings reveal that the fire load density within the EPFC framework can be modified to better represent the severity of fire ex- periments. This approach ensures physical consistency of the obtained compartment gas temperatures, as opposed to alternative approaches for addressing the EPFC model uncertainty. While promising results are evident in this proof of concept, exploration for other types of structural elements and evaluation for structural systems is necessary before integration into design practices.
Keywords: structural fire engineering, compartment fires, fire load density, steel structures, reliability, probability of failure
Published in DiRROS: 17.04.2024; Views: 124; Downloads: 34
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7. Utilisation of reused steel and slag : analysing the circular economy benefits through three case studiesGenesis Camila Cervantes Puma, Adriana Salles, Janez Turk, Viorel Ungureanu, Luís Bragança, 2024, review article Abstract: This research explores sustainable construction practices focusing on material reuse, specifically reclaimed structural steel and slag. In general, the building stock is not designed for deconstruction, and material recovery for reuse at the end of life of buildings is complex and challenging. The study evaluates the benefits of content reuse through a thorough analysis of three case studies— BedZED eco-friendly housing, Angus Technopôle building, and the use of steel slag aggregate in road construction. It highlights the value of reclaimed structural steel and by-products like steel slag in waste reduction, energy conservation, and resource preservation. The BedZED case study showcases recycled steel’s cost-effectiveness and economic viability in construction, while the Angus Technopôle building exemplifies the adaptive reuse of an old steel frame building. Additionally, the third case study showcases the benefits of using Electric Arc Furnace C slag in asphalt-wearing courses, highlighting the reduction in greenhouse gas emissions and environmental impact. The versatility of reclaimed structural steel and slag is evident in integrating material reuse in building construction and road infrastructure. These case studies illustrate the potential for reusing steel and its by-products in various construction contexts, from eco-friendly housing to road development. Therefore, the study aims to demonstrate the feasibility and benefits of sustainable practices within the construction industry by showcasing the successful incorporation of reclaimed steel and slag in these projects. Considering the significant contributions of building construction to global greenhouse gas emissions, raw material extraction, and waste production, the study advocates for adopting circular economy (CE) principles within the construction industry. Finally, the analysis of case studies underscores the advantages of reclaimed structural steel and the valorisation of steel slag through the lens of CE and their contribution to sustainable development.
Keywords: circular economy, reused steel, steel slag aggregate, reclaimed steel, steel members
Published in DiRROS: 12.04.2024; Views: 170; Downloads: 63
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9. Sliding wear behaviour of conventional and cryotreated PM Cr-V (Vanadis 6) ledeburitic tool steelVenu Yarasu, Peter Jurči, Peter Gogola, Bojan Podgornik, Marko Sedlaček, 2023, original scientific article Keywords: cold work tool steel, conventional treatment, cryogenic treatment, hardness, reciprocal sliding, wear
Published in DiRROS: 08.04.2024; Views: 176; Downloads: 30
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10. The effect of heat treatment on the interface of 155 PH martensitic stainless steel and SAF 2507 duplex steel in functionally graded AM componentsMartina Koukolíková, Pavel Podaný, Sylwia Rzepa, Michal Brázda, Aleksandra Kocijan, 2023, original scientific article Abstract: Multi-material components, also known as functionally graded materials (FGMs), are innovative materials that possess unique properties due to their composition and have many potential applications in engineering and science. The effect of the heat treatment (HT) of functionally graded materials 15–5 precipitation-hardened (PH) martensitic steel and SAF 2507 duplex stainless steel (and the opposite order of deposition, i.e. SAF 2507 first followed by 15–5 PH stainless steel) on the interface microstructures was systematically investigated in the presented research. The choice of HT followed the trend of optimum post-processing for the individual alloys. A significant modification in the interface microstructure, characterized in the microstructural transition zone (MTZ) formed above the fusion line. Mechanical properties by miniaturized testing method including hardness measurement characterized both types of interfaces. The sequence of the materials’ application did not have a significant effect on their final mechanical tensile properties in the heat-treated states. Nevertheless, the microstructural change at the MTZ led to drop in the hardness at the interface. The research presents heat-treated FGMs in a horizontal configuration to form a high-quality metallurgical joint between heterogeneous materials manufactured by powder-based directed energy deposition method.
Keywords: heat treatment, additive manufacturing, martensitic stainless steel, duplex steel, microstructure, mechanical properties
Published in DiRROS: 04.04.2024; Views: 147; Downloads: 28
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