1. 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: 358; Prenosov: 208
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2. 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: 483; Prenosov: 240
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3. 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: 560; Prenosov: 294
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5. 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: 679; Prenosov: 299
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8. Laser surface modification of CRVN coatings for self-lubricating performanceBojan Podgornik, Barbara Šetina, Miha Čekada, Suman Chatterjee, Dermot Brabazon, 2025, objavljeni znanstveni prispevek na konferenci Ključne besede: CrVN coating, laser modification, hot forming, self-lubrication, wear, friction
Objavljeno v DiRROS: 14.05.2025; Ogledov: 546; Prenosov: 190
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9. Combining ultrafast laser texturing and laser hardening to enhance surface durability by improving hardness and wear performanceAbhijit Cholkar, Suman Chatterjee, Sujith Kumar, Marko Sedlaček, Bojan Podgornik, David Kinahan, Dermot Brabazon, 2024, izvirni znanstveni članek Povzetek: Aluminum alloy 7075 is utilized widely across marine, aerospace, and automotive sectors. However, its surface wear resistance has hindered its application in certain tribological environments. Addressing this challenge, the current study examines a hybrid laser method to increase surface wear resistance by combining two techniques: ultrafast laser texturing and laser-based surface hardening. Ultrafast laser processing is conducted using 3 W laser power, 100 kHz pulse repetition rate, 4 mm s-1 scanning speed, and three different scan patterns. After the texturing operation, laser-based surface hardening is then performed on these textures using a continuous wave laser. The laser heat treatment is conducted using laser powers of 400 and 500 W with three different scan speeds of 1, 2, and 3 mm s-1 . Microhardness evaluations show a notable increase in hardness, with the hardest sample exhibiting a 17.8% increase compared to the pristine sample. The lasertextured and laser heat-treated samples exhibit a significant reduction in the average coefficient of friction and wear volumes compared to samples that were laser-textured but not laser heat-treated. The investigated laser processing strategy offers a promising approach for surface modification, enhancing both mechanical properties and wear resistance of aluminum alloy 7075 surfaces.
Ključne besede: hardness, laser hardening, parametric modeling, surface modification, ultrafast laser texturing, wear resistance
Objavljeno v DiRROS: 05.11.2024; Ogledov: 852; Prenosov: 1089
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10. Enhancing magnesium bioactivity for biomedical applications : effects of laser texturing and sandblasting on surface propertiesMarjetka Conradi, Aleksandra Kocijan, Bojan Podgornik, 2024, izvirni znanstveni članek Povzetek: Magnesium and its alloys, valued for their lightweight and durable characteristics, have garnered increasing attention for biomedical applications due to their exceptional biocompatibility and biodegradability. This work introduces a comparison of advanced and basic methods—laser texturing and sandblasting—on magnesium surfaces to enhance bioactivity for biomedical applications. Employing a comprehensive analysis spanning surface morphology, hardness, wettability, tribological performance, and corrosion behavior, this study elucidates the intricate relationship between varied surface treatments and magnesium’s performance. Findings reveal that both laser texturing and sandblasting induce grain refinement. Notably, sandblasting, particularly with a duration of 2 s, demonstrates superior wear resistance and reduced corrosion rates compared to untreated magnesium, thereby emerging as a promising approach for enhancing magnesium bioactivity in biomedical contexts. This investigation contributes to a deeper understanding of the nuanced interactions between diverse surface treatments and their implications for magnesium implants in chloride-rich environments, offering valuable insights for prospective biomedical applications.
Ključne besede: biomaterial, microstructure, hardness, friction/wear, corrosion
Objavljeno v DiRROS: 18.10.2024; Ogledov: 765; Prenosov: 12815
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