Кафедра матеріалознавства та прикладної механіки (МПМ)
Постійне посилання колекціїhttps://dspace.mipolytech.education/handle/mip/18
Переглянути
3 результатів
Результати пошуку
Документ Influence of heat treatment on the structure and wear resistance at abrasive wearing of high-carbon chromonickel steel of 150H15N5VM type(Фізико-технологічний інститут металів і сплавів НАН України, 2023) Pashynskyi, V. V.; Pashynska, O. H.; Boyko, I. O.; Пашинський, В. В.; Пашинська, О. Г.; Бойко, І. О.The article is devoted to the improvement of heat treatment regimes of steel 150H15N5VM type to ensure the necessary operational characteristics of the tool. The wear resistance of the alloys during abrasive wear was studied by the method of friction against a fixed abrasive. Formation of different structural states was performed by annealing of cast steel at temperatures of 550–900 °C, as well as quenching from temperatures of 950–1100 °C, followed by tempering in the range of 550–850 °C. The structure of the steel was studied by optical metallography and the morphology of the wear surfaces – by scanning electron microscopy. As a result of research, it was established that high-chromium steel with nickel addition in the cast state has increased stability of retained austenite. To obtain maximum hardness, cast steel should be heated in the temperature range of 740 ... 790 °C for 2 ... 4 hours. As a result of annealing and following quenching with tempering, two variants of the structural state with increased wear resistance are formed – martensite and retained austenite immediately after tempering and the products of tempering of martensite and decay of retained austenite at high tempering. Wear resistance increases with increasing of quenching temperature. The main mechanism of wear is microcutting of the surface by hard abrasive particles. The drop in wear resistance at tempering temperatures of 550–650 °C is a consequence of a decrease in hardness and is accompanied by changes in the micromechanism of the wear surface destruction – the appearance of local centers of destruction. A significant increase in wear resistance with a further increase in tempering temperature, especially at small specific loads, can be explained by the formation of special carbides of alloying elements in the matrix.Документ Development of quality control and structure parameters determination methods for large size products from sintered hard alloys WC-(Co+Ni+Cr) based on analysis of the ultrasonic oscillations spreading parameters(ПП "ТЕХНОЛОГІЧНИЙ ЦЕНТР"; Полтавський державний аграрний університет, 2021) Pashynskyi, V. V. ; Boyko, I. O.; Пашинський, В. В.; Бойко, І. О.The object of research is hard alloys with a morphology of the carbide phase skeleton structure, in which particles contact with each other, and the gaps between them are filled with a binder phase. The mechanical and service characteristics of such materials depend on the degree of development of the skeleton structure. One of the most problematic areas is the lack of non-destructive methods for determining the parameters of the structure. The introduction of such techniques will allow obtaining objective information on the structure of the material and using it to evaluate the quality of products. In the course of the study, the parameters of the scattering of elastic vibrations in inhomogeneous media were determined. The main hypothesis of the study is the assumption that the processes of energy dissipation occur both in the structural elements themselves (carbide grains and bond areas) and at their boundaries. Therefore, the evaluation of dissipation processes will allow obtaining a quantitative estimation of the alloys structure parameters, and will allow assessing the quality of the material. The following characteristics were chosen as the parameters characterizing the propagation of ultrasonic oscillations: the speed of the oscillations propagation, the scattering background level in relation to the amplitude of the bottom reflection, the oscillations attenuation coefficient. The parameters were determined and compared with the characteristics of the quality of the products and the parameters of the microstructure, which were determined by the methods of quantitative metallography and the statistical characteristics of the relationship between the parameters, were determined. As a result, new quality control procedures for carbide products have been developed. The contiguity characteristics of the carbide skeleton of the sintered cemented carbide were determined by measuring the propagation speed of ultrasonic oscillations. The assessment of the level of porosity with a pore size of less than 1 mm was carried out according to the results of measuring the relative amplitude of the background scattering of ultrasonic oscillations. The proposed methods are non-destructive and are carried out in one cycle with ultrasonic flaw detection, to which 100% of the products are subjected. These techniques have been introduced in the production of carbide rolls by the method of controlled hot vacuum pressing. They have become an integral part of the quality control system for carbide rolls.Документ Study of the influence of the increased carbon content in electrodes on structure and properties of the welding seam during welding of 110G13 steel.pdf(ПП "ТЕХНОЛОГІЧНИЙ ЦЕНТР"; Полтавський державний аграрний університет, 2021) Пашинський, В. В.; Бойко, І. О.; Pashynskyi, V. V. ; Boyko, I. O.The object of research is the effect of the carbon-forming component of coated electrodes for welding and surfacing of Gadfield steel (110G13L and analogs) on the structure and properties of the weld. One of the most problematic areas in the welding and surfacing of high-carbon steel is the high irregularity of the rod and coating melting rates. Therefore, the non-melted part of the coating is literally poured into the weld pool, which leads to significant chemical and structural inhomogeneity of the welded metal. The main hypothesis of the study is the assumption that it is possible to increase the homogeneity of the deposited metal by changing the conditions for the transition of carbon from the electrode to the weld pool by using an electrode rod made of carbon steel. In the course of the study, electrode rods with different carbon contents were used. With an increase in the carbon content in the composition of the electrode rod, the fluidity of the drops increased, which contributed to a decrease in the strength of the welding current without harm to the welding and technological characteristics. This allows to reduce the generation of heat in the base metal, that is an effective measure to prevent hot cracks in the weld metal and heat affected zone Studies of the composition of the electrode metal droplets and the weld material showed that with an increase in the carbon content in the electrode rod from 0.08 % to 0.8 %, the carbon content in the droplets increases from 0.3 % to 0.97 %. The carbon content in the weld metal is 1.1 %. The assimilation of manganese by a drop increases with an increasing of coating and the droplet interaction time. A significant increasing in the rate of coating melting was obtained. This is due to the fact that the concomitant decrease in the content of graphite in the coating contributes to a decrease in the refractoriness of the electrode coating.