Iskanje po repozitoriju

A+ | A- | | SLO | ENG

Povzetek: 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.
Ključne besede: heat treatment, additive manufacturing, martensitic stainless steel, duplex steel, microstructure, mechanical properties
Objavljeno v DiRROS: 04.04.2024; Ogledov: 66; Prenosov: 17
Povezava na datoteko

Povzetek: Larch (Larix decidua) showed good growth and adaptability to ecological conditions in Bosnia and Herzegovina. The research aims to determine the variability of the morphological traits of larch in the seed stand near Kakanj, the variability at the beginning of heartwood formation, and correlations among these properties.In the larch seed stand, established by seedlings 2+0 in 1979, an area of 0,45 hectares was set aside. The heights and breast height diameters of the trees were on that area were measured in 2002 and 2020, and the basal area and volume were calculated. In 2020, the trees were drilled at breast height with a Presler drill to measure the proportion of heartwood. Average values of all properties for 2002 and 2020 were calculated. The ten, five and one best trees were selected according to the properties of breast height diameter, height, basal area, volume, and the intensities of selection for these traits were calculated. The Pearson correlation coefficient among all investigated traits were calculated. The average breast height diameter of 41-year-old trees was 24,6 cm, average height 21,8 m, basal area 0.0499m2 and volume 0.3745 m3 (table 1), while in 2002. the average breast height diameter was 15,5 cm, height 18,2 m, basal area 0,020 m2, and volume 0,128 m3 (table 1). Between 2002 and 2020, there was an overtaking of trees in breast height diameter and height and thus the base and volume (table 2). The average larch tree starts heartwood formation at the age of 14 years (table 1). The earliest heart-wood formation occurs in the sixth year (tree 495) and the latest in the 32nd year (table 4). Pearson coefficient showed a high positive correlation between breast height diameter and height in 2002 (ta-ble 9), which means that trees with a good height increase also have a good thickness increase. As a result, the correlation between breast height diameter and basal area and breast height diameter and volume, height and basal area, height and volume, and basal area and volume are statistically signifi-cant. Pearson’s correlation coefficient for the year 2020 showed a negative correlation between the be-ginning of heartwood formation and all other traits (table 10), i.e., trees that formed heartwood earlier have higher values of growth traits.The results will be used in the selection processes of larch individuals with good height and thickness growth and early heartwood formation.
Ključne besede: European larch, morphological properties, core formation, selection
Objavljeno v DiRROS: 25.03.2024; Ogledov: 110; Prenosov: 56
Celotno besedilo (255,90 KB)
Gradivo ima več datotek! Več...

Ključne besede: hot-work tool steel, friction, sliding wear, mechanical properties
Objavljeno v DiRROS: 08.03.2024; Ogledov: 102; Prenosov: 50
Celotno besedilo (2,04 MB)
Gradivo ima več datotek! Več...

Povzetek: The amount of waste material and side products of various industrial plants is increasing, which leads into waste accumulation and lack of space in disposal landfills. Paper industry, with its side products paper sludge and ash, faces these same issues. To reduce the accumulation of these materials, we explored the possibility of their use in construction. At first a series of geomechanical tests was conducted on a product consisting of fly ash and bottom ash. Based on the laboratory results test fields were constructed, where the preparation and installation technologies were tested. The fields were exposed to the atmospheric conditions, so durability of the product in the natural environment was proven. Since the composition of both fly ash and bottom ash depends on the paper industry process, a continuous monitoring of their characteristics was established.
Ključne besede: paper industry, fly ash, bottom ash, construction material, geomechanical properties
Objavljeno v DiRROS: 05.03.2024; Ogledov: 146; Prenosov: 52
Celotno besedilo (521,45 KB)
Gradivo ima več datotek! Več...

Ključne besede: spring steel, 54SiCr6 steel, microstructure, mechanical properties
Objavljeno v DiRROS: 02.02.2024; Ogledov: 215; Prenosov: 74
Celotno besedilo (1,44 MB)
Gradivo ima več datotek! Več...