Browsing by Author "Repyakh, Serhii I."

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    Assessing Criteria for Casting and Deformation Suitability of Metals and Alloys
    (Dnipro University of Technology, Dnipro, 2025) Kimstach, Tetiana V.; Uzlov, Kostiantyn I.; Bilyi, Oleksandr P.; Mazorchuk, Volodymyr F.; Repyakh, Serhii I.
    ENG: Purpose. Based on existing criteria for predicting the suitability of metals and their alloys for manufacturing products from them by deformation or casting analysis develop a set of dimensionless parametric criteria and their quantitative scales. Their using will allow increasing the predicting accuracy of metals and alloys for their processing by pressure or casting suitability and feasibility. Methodology. The work uses phenomenological approach to systematic analysis results of metals and alloys mechanical and individual casting properties interpreting under uncertainty conditions, drawing on literature reference data, expert evaluation data and the authors’ own research results. The authors’ own data have been obtained experimentally using standard methods for mechanical properties determining and due to original authors’ method for technical purity metals and alloys based on them cast samples values of their absolutely hindered linear shrinkage determination during casting. Findings. The authors first proposed parametric dimensionless criteria and scales to them (criteria groups). Their application allows one, through such groups combinations, to assess suitability of any alloy or metal for its use possibility for products manufacturing by casting and/or pressure processing. Originality. For the first time dimensionless parametric criteria have been developed and proposed for use at initial stages of new alloys or technologies elaboration for products from them manufacturing as well as their quantitative scales for preliminary assessment (prognosis) of alloys processing feasibility by pressure or casting, regardless of their type and method. Practical value. Developed criteria and their quantitative scales using will allow alloys developers and specialized enterprises employees to save time and expenses both for alloy elaboration and for its implementation into production.
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    Si and Mn Effect on Mechanical Properties and Linear Shrinking of Non-Magnetic Cu-Al System Cast Bronzes
    (Dnipro University of Technology, Dnipro, 2025) Kimstach, Tetiana V.; Uzlov, Kostiantyn I.; Bilyi, Oleksandr P.; Repyakh, Serhii I.
    ENG: Purpose. To establish Si and Mn influence on mechanical properties level at 20 °C and aluminum bronzes structure with Al from 3 to 9 % mass content investigation. Methodology. Cast bronzes mechanical properties have been determined based on their fracture results on FP-100/1 machine and PSW-30 pendulum impactor. Microstructure has been examined using Neophot-21 optical microscope. Bronzes linear shrinkage coefficients have been calculated based on results of determining cast cylindrical samples lengths changes. Si and Mn complex influence on bronzes properties has been determined by the results of simplex triangles according to H. Scheffer plan constructing. Temperature has been measured with chromel-alumel thermocouple completed with electronic potentiometer. Bronzes chemical composition has been determined on ­EXPERT 4L analyzer. Findings. Silicon (up to 2 %) and manganese (up to 2 %) adding to Cu-Al system bronze, while aluminum content from 9 to 3 % reducing, leads to bronze ultimate tensile and yield strength decreasing during stretching and its plasticity increasing. At the same time, bronze structure, at any combination of Al, Si and Mn contents within their changes in studied limits, remains single-phase. Originality. For the first time, comprehensive assessment of influence of Si and Mn with simultaneous decrease in Al content on mechanical properties and linear shrinkage of Cu-Al-Si-Mn system cast bronzes has been carried out. It has been established that all bronzes of studied compositions have a single-phase structure and mechanical properties level that is inherent for pressure-worked bronzes. Practical value. The research results expand understanding about elemental and complex influence of Si and Mn on aluminum bronzes properties, provide an opportunity to choose a bronze with properties required level from its cast billet for deformation or to design castings taking into account the linear shrinkage values discovered in this work. The data obtained can also be the basis for new foundry, corrosion-resistant, non-magnetic bronzes, which have strength and density at the level of some carbon steel grades, development. Such materials have been used for parts that operate in chemically aggressive environments manufacturing, for control and measuring equipment and devices parts, for ship parts and naval devices, fittings, bushings, couplings, intrinsically safe tools, etc.