Papers by Keyword: Grain-Size Distribution

Abstract: The article presents a technique for assigning the composition of the agglutinant sand, which is based on the calculation and experimental approach to determining the composition, taking into account the quality of raw materials used and the requirements for the properties of concrete products produced. The obtained results served as the basis for the practical implementation of the proposed technological method of increasing the small-sized products durability made of fine-grain concrete.

Abstract: To predict structuring and to produce Fe-Cr-Ni-Graphite-based powdered alloys with tailor-made properties, the component diffusion coefficients have been determined that allow calculating sintering or homogenizing annealing parameters of heterogeneous charge products. It has been revealed that Fe, Cr and Ni heterodiffusion coefficients are influenced not only by their own concentration, but also by structuring kinetics and the number and distribution of the graphite in charge. The electron-probe test shows the distribution of the components in the in-terparticle contact zones. Using the Motano’s, the Lubov’s and the Maksimov’s methods, the values of mutual diffusion coefficients depending on the component concentration have been determined. Using Darken’s ratios and having experimentally determined the component interparticle zones and the displacement distance, the partial heterodiffusion coefficients have been calculated. The given paper proves that the powder-component grain-size distribution alloys should be selected on the basis of relative values of the heterodiffusion coefficients.

Abstract: This issue deals with peculiarities of stress-strain state forming in a representative volume of inhomogeneous soil. Analytic solutions for describing such stress states and obtaining equivalent mechanical values for such massive are given. Basing on the performed triaxial laboratory tests the impact of diameter ratio, percentage, and contact between particles on mechanical properties of a mixture is estimated. As a conclusion some recommendations on using the research results in practical geotechnical engineering are given. The classification of inhomogeneous soils, based on granulometric data, allowing to estimate mechanical properties is presented, as a method of granulometric composition, humidity and density selection for artificial foundations.

Abstract: Bimodal grain size distributions were found in continuously cast slab and thermomechanical controlled rolled (TMCR) samples of Nb-microalloyed steel. Scanning electron microscopy (SEM) revealed inhomogeneous distributions of Al- and Nb-containing precipitates, which were found to pin prior austenite grain boundaries during reheating. An effort has been made to establish parameters to quantify the extent of bimodality of reheated and rolled microstructures. Quantification of bimodality using peak grain size range, (PGSR) and peak height ratio, (PHR), is found to match closely with the visual observation of bimodality. Thermo-Calc software was used to predict the sequence of precipitation for different compositions and that could explain the formation of bimodality during reheating.