1. Processing aluminium EN AW 7075 alloy using selective laser meltingNejc Velikajne, Jože Medved, Matjaž Godec, Irena Paulin, complete scientific database of research data Abstract: Selective laser melting (SLM) is an additive manufacturing process, forming the desired geometry by selective layer fusion of powder material. Unlike conventional manufacturing processes, highly complex parts can be designed and manufactured with high accuracy and little post processing. Currently, different types of steel, aluminium, titanium and nickel-based alloys have been successfully processed; however, high strength aluminium alloy EN AW 7075 has not been processed with satisfying quality. The main focus of the investigation is to develop a new alloy which is more suitable for the SLM process for the wide used aluminium alloy EN AW 7075. But before that, gas-atomized powder material was characterized in terms of statistical distribution. A wide range of process parameters and different pre-heating temperatures were selected to optimize the process in terms of optimum volume density and reducing the effect of hot cracking. However, all laser-melted parts exhibited hot cracks which typically appear in aluminium alloy EN AW 7075.
Keywords: EN AW 7075, aluminium alloy, hot cracks, relative density, selective laser melting (SLM)
Published in DiRROS: 22.04.2024; Views: 71; Downloads: 0 |
2. Effect of steel’s thermal condition on the transformation temperatures of two hot-work tool steels with increased thermal conductivity : Tilen Balaško, Jaka Burja, Jožef MedvedTilen Balaško, Jaka Burja, Jože Medved, 2023, original scientific article Keywords: thermal analysis, hot-work tool steels, differential scanning calorimetry, heat treatment
Published in DiRROS: 08.03.2024; Views: 92; Downloads: 50
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4. Enhancing ductility of hot-work tool steel through isothermal bainitic transformationAnže Bajželj, Aleš Nagode, Tilen Balaško, Barbara Šetina, Jaka Burja, 2024, published scientific conference contribution Abstract: Hot-work tool steels are extensively used in industrial applications that require high resistance to mechanical and chemical degradation at elevated temperatures. To meet these requirements, hot-work tool steels must exhibit good mechanical properties, including high tensile strength, hardness, wear resistance, and tempering resistance, as well as high thermal conductivity and ductility. This study investigates the ductility of the hot-work tool steel HTCS-130, which suffers from low ductility due to the presence of stable molybdenum-tungsten carbides (M6C) on the prior austenite crystal grain boundaries. Increasing austenitisation temperatures or prolonging the dwelling time at temperature can promote intensive migration of grain boundaries, leading to negative effects on the mechanical properties of the steel. To address this issue, isothermal transformation in the bainitic area between 350 and 500 °C was performed. Isothermal transformation at around 350 °C leads to the formation of lower bainite, which has similar hardness to tempered martensite. As the temperature of isothermal transformation increases, the hardness of the material decreases, due to the formation of upper bainite. The hardness analysis was measured using the Vickers method, the impact toughness of the steel samples was measured using a Charpy test with V-notched samples. The microstructure characterization was performed using optical and scanning electron microscopy. The improvement of ductility can be achieved by controlling the isothermal transformation of bainite and adjusting the heat treatment conHot-work tool steels are extensively used in industrial applications that require high resistance to mechanical and chemical degradation at elevated temperatures. To meet these requirements, hot-work tool steels must exhibit good mechanical properties, including high tensile strength, hardness, wear resistance, and tempering resistance, as well as high thermal conductivity and ductility. This study investigates the ductility of the hot-work tool steel HTCS-130, which suffers from low ductility due to the presence of stable molybdenum-tungsten carbides (M6C) on the prior austenite crystal grain boundaries. Increasing austenitisation temperatures or prolonging the dwelling time at temperature can promote intensive migration of grain boundaries, leading to negative effects on the mechanical properties of the steel. To address this issue, isothermal transformation in the bainitic area between 350 and 500 °C was performed. Isothermal transformation at around 350 °C leads to the formation of lower bainite, which has similar hardness to tempered martensite. As the temperature of isothermal transformation increases, the hardness of the material decreases, due to the formation of upper bainite. The hardness analysis was measured using the Vickers method, the impact toughness of the steel samples was measured using a Charpy test with V-notched samples. The microstructure characterization was performed using optical and scanning electron microscopy. The improvement of ductility can be achieved by controlling the isothermal transformation of bainite and adjusting the heat treatment conditions. These findings provide useful insights into the design and optimization of heat treatment processes for hot-work tool steels.ditions. These findings provide useful insights into the design and optimization of heat treatment processes for hot-work tool steels.
Keywords: hot-work tool steel, austempering, bainitic transformation, ductility, dilatometry
Published in DiRROS: 28.02.2024; Views: 156; Downloads: 69
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5. Grain size distribution of DP 600 steel using single-pass asymmetrical wedge testUrška Klančnik, Peter Fajfar, Jan Foder, Heinz Palkowski, Jaka Burja, Grega Klančnik, 2023, original scientific article Keywords: wedge test, hot-rolling, grain size distribution, dual-phase steel
Published in DiRROS: 07.02.2024; Views: 177; Downloads: 74
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6. Effects of variated final temperature and workpiece thickness for hot rolling of aluminum alloy EN AW-8011Jakob Kraner, Peter Cvahte, Primož Šuštarič, Tomaž Šuštar, Črtomir Donik, Irena Paulin, Shae K. Kim, Kjung Il Kim, 2023, original scientific article Keywords: aluminum alloy, hot rolling, simulations, metallography, mechanical properties
Published in DiRROS: 01.02.2024; Views: 145; Downloads: 79
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7. High temperature friction and galling properties of nanolayered (Cr,V)N coatings and effect of V contentBojan Podgornik, Marko Sedlaček, Barbara Šetina, Miha Čekada, 2023, original scientific article Keywords: (Cr, V)N coating, galling, high-temperature tribology, hot forming, self-lubrication
Published in DiRROS: 26.01.2024; Views: 210; Downloads: 130
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8. Evaluation and metrological performance of a novel ionisation vacuum gauge suitable as reference standardKarl Jousten, Sylke Bechstein, Matthias Bernien, Frédéric Boineau, N. Bundaleski, Claus Illgen, Berthold Jenninger, Janez Šetina, Ricardo A. S. Silva, Anke Stöltzel, O. M. N. D. Teodoro, Martin Wüest, 2023, original scientific article Keywords: ionisation vacuum gauge, hot cathode, sensitivity, secondary electrons, ion induced secondary electron yield
Published in DiRROS: 26.01.2024; Views: 207; Downloads: 94
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9. Optimizing hot-work tool steel microstructure for enhanced toughnessAnže Bajželj, Tilen Balaško, Barbara Šetina, Jaka Burja, 2024, original scientific article Keywords: hot-work tool steel, austempering, bainitic transformation, lower bainite, impact toughness
Published in DiRROS: 24.01.2024; Views: 216; Downloads: 94
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