1. Effects of boriding and niobium carbide coating on the microstructure, hardness, and tribocorrosion properties of Vanadis 6 tool steelVenu Yarasu, Bojan Podgornik, Tadeja Kosec, Peter Jurči, Ali Günen, Peter Orihel, Sabri Alkan, 2026, izvirni znanstveni članek Povzetek: Vanadis 6 (V6) cold work tool steel is widely used in cold forming applications due to its high wear resistance and toughness. However, tribocorrosion remains a major challenge in aggressive manufacturing conditions limiting the tool life. This study investigates the effect of boride and niobium (NbC) coatings on the microstructure, hardness, and tribocorrosion properties of V6 tool steel. Both uncoated and coated samples were tested in 0.1 M NaCl (pH 7), 0.001 M NaOH (pH 11), and Na-tetraborate (pH 10) solutions. The microstructural changes and phase analysis were examined via a scanning electron microscope coupled with energy-dispersive spectroscopy (SEM-EDS) and X-ray diffraction, while the hardness was evaluated using Vickers microhardness (HV). The tribocorrosion tests were performed by monitoring the open circuit potential (OCP) with a reciprocating pin-on-disk configuration. Wear surface analysis was conducted using 3D confocal microscopy, Raman spectroscopy, and SEM-EDS techniques. The findings indicated that the application of coatings enhanced the surface hardness from 710 HV30 to 2000 HV0.1 and 1550 HV0.1 for boride and NbC coatings, respectively. During the tribocorrosion experiments, the samples coated with NbC and borides consistently displayed the highest open-circuit potential (OCP) in all the solutions. These results confirm that both NbC and borides improved the tribological and corrosion resistance of Vanadis 6 steel, with the NbC coating offering a more effective and stable protective layer. The outcome of this study emphasizes the critical role of coatings and the appropriate choice of electrolytes for comparative evaluation in the tribocorrosion behavior of cold work tool steels.
Ključne besede: Vanadis 6 steel, surface modifications, microstructure, ribocorrosion
Objavljeno v DiRROS: 11.06.2026; Ogledov: 324; Prenosov: 302
 Celotno besedilo (17,92 MB)
Gradivo ima več datotek! Več... |
2. Influence of build orientation and heat treatment on mechanical, tribological, and corrosion performance of LPBF Inconel 625Danijela Anica Skobir Balantič, Črtomir Donik, Bojan Podgornik, Aleksandra Kocijan, Matjaž Godec, 2026, izvirni znanstveni članek Ključne besede: Inconel 625, additive manufacturing, build orientation, strength, impact toughness, wear, corrosion behaviour
Objavljeno v DiRROS: 25.05.2026; Ogledov: 422; Prenosov: 373
Celotno besedilo (21,26 MB)
Gradivo ima več datotek! Več... |
3. |
4. Influence of carbide morphology and matrix hardness on the sliding wear behaviour of tool steelsMarko Sedlaček, Božo Skela, Bojan Podgornik, 2026, izvirni znanstveni članek Povzetek: When using tool steels with martensitic microstructure, the hardness is regarded as one of the main criteria defining its wear properties. The premise is that the harder the material, the greater the sliding wear resistance. This is especially common when using tool steels, as the highest possible hardness is pursued, but the influence of the microstructure is often neglected. Presence of different carbides in terms of fraction, type and size (morphology) in martensitic matrix has different effects on wear, especially if matrix hardness changes. The objective of this study was to establish a correlation between the fraction and morphology of V and Cr-rich carbides in tool steel with its microstructure, fracture toughness, and overall influence on material sliding wear resistance. To achieve this, commercially available tool steels (Mat. No. 1.2379 cold work tool steel and modified Mat. No. 1.2367 hot work tool steel) were selected, exhibiting notably diverse microstructures, particularly in terms of carbide fraction and morphology. To enable a direct comparison, both steels underwent heat treatment to attain three distinct hardness levels: 45 + /-1 HRC, 49 + /-1 HRC, and 54 + /-1 HRC. Sliding wear resistance and behavior under various contact conditions were correlated with microstructure, specifically focusing on hard carbides. Additionally, the study examined the effect of wear particles being trapped within or removed from the tribological contact. It was observed that the sliding wear behavior is significantly influenced when the microstructure comprises a martensitic matrix with a higher fraction of carbides, particularly coarse eutectic M7C3 carbides, especially if the matrix hardness is insufficient. Matrix hardness plays a crucial role in preventing carbide detachment from the matrix. Plastic deformation of the tempered martensite matrix, along with carbide cracking and detachment from the matrix, was identified as contributing factors intensifying wear during the wear process.
Ključne besede: tool steel, hardness, sliding wear, carbide fraction, fracture toughness, reciprocating sliding, third-body abrasion
Objavljeno v DiRROS: 30.03.2026; Ogledov: 416; Prenosov: 355
Celotno besedilo (11,31 MB)
Gradivo ima več datotek! Več... |
5. Friction and galling reduction potential of ▫$Ni-Ag-MoS2$▫ coating by laser metal deposition at intermediate temperaturesBojan Podgornik, Venu Yarasu, Barbara Šetina, Manel Rodríguez Ripoll, 2026, izvirni znanstveni članek Ključne besede: laser metal deposition, galling, hot forming, solid lubricant, friction
Objavljeno v DiRROS: 02.03.2026; Ogledov: 558; Prenosov: 449
Celotno besedilo (22,26 MB)
Gradivo ima več datotek! Več... |
6. Effect of deep cryogenic treatment on aging behavior and properties of Al-Mg-Si alloyBojan Podgornik, Matic Klug Jovičević, Patricia Jovičević Klug, 2023, objavljeni znanstveni prispevek na konferenci Ključne besede: deep cryogenic treatment, Al-Mg-Si alloy, aging, microstructure, hardness, fatigue
Objavljeno v DiRROS: 08.07.2025; Ogledov: 895; Prenosov: 507
Celotno besedilo (425,38 KB)
Gradivo ima več datotek! Več... |
7. Influence of laser beam shape and post heat-treatment on the microstructure and mechanical properties of nickel-based alloy IN718 manufactured by laser powder bed fusionMatjaž Godec, Narges Mirzabeigi, Črtomir Donik, Danijela Anica Skobir Balantič, Simon Malej, Irena Paulin, Bojan Podgornik, Jonas Grünewald, Tobias Novotny, Florian Bayer, Francisco Ruiz-Zepeda, Katrin Wudy, 2025, izvirni znanstveni članek Povzetek: This study examines the effect of Gaussian and ring-shaped laser beam profiles on the microstructural development and mechanical properties of the PBF-LB/M processed nickel-based alloy Inconel 718 in its as-built and post-heat-treated conditions. Beam shaping was employed to achieve a faster build rate without compromising material properties. One of the objectives was to optimise heat treatment conditions for the beam-shaped profile. The post-heat-treatment process included four different solution annealing temperatures (954 °C, 984 °C, 1034 °C and 1154 °C), followed by two-step ageing, respectively. The microstructure evolution was revealed using scanning electron microscopy (SEM) equipped with energy-dispersive X-ray diffraction (EDS). The mechanical properties in all investigated conditions were evaluated based on tensile tests at room temperature. Using a Gaussian laser beam profile results in a fine-grained microstructure without a strong columnar orientation, while the ring beam profile produces a distinct columnar structure with larger nanodendritic grains and dislocation cells. Both beam profiles exhibit a similar proportion of Laves phase. After post-heat treatment, the Gaussian beam profile generally provides 3-7 % higher mechanical properties. The differences in mechanical properties between horizontal and vertical building directions are greater for ring-shaped laser beam profiles. Heat-treatment temperature above 1034 °C leads to recrystallisation, grain growth and the formation of carbonitrides which reduce mechanical properties. Based on the results, the proposed optimal heat-treatment temperature for both investigated laser beam shapes is 984 °C. At this temperature, tensile strength equalises between horizontal and vertical build directions while yield strength increases, which is beneficial for most applications.
Ključne besede: PBF-LB/M, beam shaping, IN718, heat treatment, mechanical properties
Objavljeno v DiRROS: 07.07.2025; Ogledov: 1242; Prenosov: 653
Celotno besedilo (28,27 MB)
Gradivo ima več datotek! Več... |
8. Tailoring the mechanical properties of PBF-LB/M Inconel 718 through post-processing: hip and heat treatmentsČrtomir Donik, Irena Paulin, Bojan Podgornik, Borut Žužek, Federico Uriati, Katrin Wudy, Matjaž Godec, 2025, izvirni znanstveni članek Ključne besede: PBF-LB/M, IN718, SEM, post-processing-heat treatment, mechanical properties
Objavljeno v DiRROS: 18.06.2025; Ogledov: 1219; Prenosov: 776
Celotno besedilo (1,91 MB)
Gradivo ima več datotek! Več... |
9. |
10. Microstructure and mechanical performance of AISI D2 tool steel after standard and modified deep cryogenic treatmentVenu Yarasu, Bojan Podgornik, Barbara Šetina, Marko Sedlaček, Črtomir Donik, Francisco Ruiz-Zepeda, 2025, izvirni znanstveni članek Ključne besede: steel, isothermal heat treatments, cyclic response, martensite, fracture toughness
Objavljeno v DiRROS: 23.05.2025; Ogledov: 1325; Prenosov: 824
Celotno besedilo (26,64 MB)
Gradivo ima več datotek! Več... |
