The aluminium alloy 6082 (AA6082) is used as a material for highly loaded construction parts, which means any improvement in its mechanical properties would be an advantage. The majority of approaches employed so far for increasing the mechanical properties only considered a small number of influential parameters and assumed that they were predominately independent of each other. In contrast, in this investigation a simultaneous increase in the yield stress and ductility (elongation) was achieved by considering a larger number of influencing parameters. For this purpose, a database of mechanical properties, process parameters and chemical compositions for the hot extruded profiles was collected. Individual and spatial analyses using a CAE neural network were performed to determine the influences of the process parameters and the alloying elements, e.g. Mg, Si, Mn, Fe, Cr and Cu, on the mechanical properties. The results of the analyses provided a new view of their influences, and the possibility to increase the mechanical properties if the process parameters in the relation with the chemical elements are closer to the optimum values. The optimum values of the process parameters and the chemical composition were assessed. In practice, the obtained values for the yield stress and the elongation confirmed the optimized values for the influential parameters as being correct, since a simultaneous increase of both properties was achieved.
COBISS.SI-ID: 1059934
In order to improve the hot workability of AISI D2 tool-steel ingots during several heats hot-deformation process, laboratory hot-compression tests as well as industrial investigations of the carbides' behaviour were carried out. The conditions that led to the occurrence of undesired, oversized carbides in the matrix were estimated and explained. The area fraction of carbides with respect to their size, their number per mm2 and their sphericity after each hot-deformation cycle were determined. It was found that too high soaking temperature results in an increased size of carbides which decreases hot workability. The results of industrial investigations show that area fraction of carbides after the end of each deformation cycle remains almost constant, but their mean size more than double during deformations in several heats which implies that the final microstructure is not dependent primarily on the last soaking-deformation cycle but depends on entire processing history, i.e. hot workability over several hot-deformation cycles can change considerably from cycle to cycle.
COBISS.SI-ID: 1287775
The assessment for realistic CO2-adsorption capacities of different rocks is important for understanding the processes associated with CO2 storage. This paper investigates the adsorption characteristics of rocks for CO2 by using a gravimetric method. The measurements were performed at 21oC with pressures from 1 up to 4 MPa. Sandstone (and clay with sand/sandstone) showed the largest adsorption capacity at 21o C. The highest amount of in situ CO2 contents in measured samples was 21.4 kg/t. The CO2 adsorption capacities were lower than past results in different coal samples. The results indicate that adsorption of CO2 into rocks may play an important role in storing CO2 in subsurface rock.
COBISS.SI-ID: 7007097
In soil mechanics the Atterberg limits are the most distinctive and the easiest property of fine-grained soils to measure. As they depend on the same physical factors as the other mechanical properties of soils, the values of the liquid and plastic limits would be a very convenient basis for their prediction. There are many studies concerning the use of the Atterberg limits in soil mechanics; however, their results vary considerably and are not generally applicable. This paper explains the main reasons for the different conclusions in these studies, which do not take into account the following: a) the water in fine-grained soils appears as interparticle and interaggregate pore water as well as adsorbed water onto the surfaces of clay minerals; b) the physical properties of fine-grained soils depend on thequantity of pore water only, because the adsorbed water is tightly tied on the clayʼs external and internal surfaces and thus cannot influence to them; c) the quantity of adsorbed water on the external surfaces of the clay minerals in soils depends mostly on the size and the quantity of the clay minerals, while the interlayer water quantity depends mostly on the quantity and the type of the swelling clay minerals in the soil composition and their exchangeable cations. From this it follows that for swelling and non-swelling soils, the uniform relationships between the Atterberg limits (which represent the total quantity of pore water and the adsorbed water onto the external and internal surfaces of clay minerals) and other physical properties does not exist. This paper presents some possibilities for the use of the Atterberg limits in predicting the soilʼs other properties for non-swelling and limited-swelling soils.
COBISS.SI-ID: 17446934
The main purpose of this article is to present a suitable geoinformational system for map charting of areas, suitable for creating waste dumps in the Republic of Slovenia. First we established a geoiformational system that bases on gathered geological data and enables an independent and clear area analysis, which helps estimate the suitability of individual areas. Their suitability was defined with the help of elimination factors. On one hand we considered the geological structure factors, types of rocks, their hydrogeology, stability and firmness, as well as ground morphology. On the other hand we considered the environmental factors as "Natura 2000", protected areas, flood areas and other.
COBISS.SI-ID: 1311327