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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: 107; Prenosov: 46
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Ključne besede: PBF-LB/M, IN718, SEM, post-processing-heat treatment, mechanical properties
Objavljeno v DiRROS: 18.06.2025; Ogledov: 129; Prenosov: 72
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Ključne besede: BFRP, corrosive environment, long-term performance, mechanical performance, experimental study
Objavljeno v DiRROS: 24.04.2025; Ogledov: 254; Prenosov: 98
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Ključne besede: hybrid composite, hand lay-up method, mechanical properties, personal protective equipment
Objavljeno v DiRROS: 24.04.2025; Ogledov: 254; Prenosov: 94
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Povzetek: Building and civil engineering conventional inorganic binding materials represent a significant burden for the environment, leading to the search for more sustainable materials. One of the potential solutions is alkali-activated materials (AAMs), which can be made solely from waste materials and at lower temperatures. However, reaction rate and solidification time depend on the precursor used. To enhance the speed of solidification, the curing temperature can be increased, but from the inside out not to create the crust on the surface, which would hinder the dehydration. Therefore, three mixtures of alkali-activated glass wool, a slow-in-alkali media solidifying precursor, were irradiated with low- and high-power microwaves in the late curing stage till complete dehydration, to determine the influence of artificial volumetric solidification onto thermomechanical behaviour of the AAM. As the electromagnetic power increased, the damages in the AAM became more severe, resulting in a reduction in mechanical strength.
Ključne besede: microwave irradiation, electromagnetic dehydration, glass wool, alkali-activated materials, mechanical performance
Objavljeno v DiRROS: 07.04.2025; Ogledov: 275; Prenosov: 218
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