Статті КПМ і ЗМ (ДМетІ)
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Browsing Статті КПМ і ЗМ (ДМетІ) by Author "Nosko, O. A."
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Item Regulations of the Formation of Bainetic Component Matrix in Economy Alloyed Chromo-Manganese Alloys(Prydniprovska State Academy of Civil Engineering and Architecture, Dnipro, 2023) Pohrebna, N. E.; Nosko, O. A.; Aiupova, Tetiana A.; Hrebenieva, А. V.; Aiupov, O. A.ENG: Purpose. The purpose of the investigation is to establish the regularities of the kinetics of supercooled austenite decomposition in the bainite temperature range (400−200 °C) in chromium-manganese cast iron for the development of thermal hardening regimes that increase the service life of products. Methodology. The object of the study are samples of research and industrial smelting of chrome-manganese cast iron containing 3,1 % carbon, 13,1 % chromium, and 15,75 % manganese. The study of the supercooled austenite decomposition kinetics was carried out by the dilatometric method in the temperature range of 400−200 °C, the study of the microstructure, phase composition, as well as the measurement of microhardness and hardness was carried out according to standard methods. Scientific novelty. The peculiarities of the supercooled austenite decomposition kinetics in the bainite temperature range (400−200 °С) in chromium-manganese cast iron were determined, the structure of the cast iron after aging consists of eutectic carbides Me (Cr, Mn, Fe)7C3, products of austenite decomposition, secondary carbides Me (Cr, Mn, Fe)7C3, Me (Cr, Mn, Fe)3C, as well as untransformed austenite in the amount of 70...75 %. The maximum hardness of the experimental cast iron was established during isothermal exposure at 350 °C for 35 hours. Practical value. The established regularities of the chromium-manganese cast iron structure formation and the determined and optimized temperature-time intervals of the supercooled austenite isothermal decomposition in cast iron are the basis for the development of heat treatment regimes to increase the strength, wear resistance of the material and the service life of its products.Item Transition from Engineering Strain to the True Strain in Analytical Description of Metals Hardening(Prydniprovska State Academy of Civil Engineering and Architecture, Dnipro, 2021) Dolzhanskyi, A. M.; Ayupova, T. A.; Nosko, O. A.; Rybkin, O. P.; Ayupov, О. А.ENG: Purpose of the work is related with the impossibility of correctly estimating the strain hardening of metals (alloys) in the area of their large total deformations due to absence of additivity in the traditionally used value of engineering strain , its nonlinear change in the area of large values, and absence of data in the technical literature Hall-Petch coefficient Ai for logarithmic true deformations, which led to the task of correct transition from the values of the engineering strain 0 < < 50...60 % to the value of the true logarithmic strainn 0 < < 1...3. Methodology. The theoretical analysis of the regularities of deformation hardening of metals (alloys) from the engineering strain is carried out, the transition from engineering to logarithmic ("true") strain of metals (alloys) by analytical representation of metal hardening graphs as a function of logarithmic (true) strain. in contrast to the degree of engineering strain is presented. Originality. Analytical expressions are presented that allow the use of known theoretical data on the strain hardening of metals (alloys) at small (50...60 %) total engineering strains during cold pressure treatment to transition to logarithmic (true) strain with large total deformations. Practical value. The obtained mathematical expressions allow to use the accumulated in the technical literature experimental data on the hardening of metals and alloys with small engineering strains in the processes of cold processing of metals (alloys) by pressure to determine the hardening with large total logarithmic (true) strains. These data can also be used to solve metallophysical problems of metal processing by pressure associated with large total compressions.