Browsing by Author "Dema R."

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    Agglomeration process productivity increasing by a sinter mix preheating
    (2019-01-01) Shapovalov A.; Dema R.; Kalugina O.; Kharchenko M.; Nefedyev S.; Koldin A.; Mihailov E.
    To increase the productivity of the agglomeration process, preheating of the charge is proposed. A series of industrial experiments was carried out on the sinter machine No. 1 of the sinter department of JSC ``Ural Steel``. The dynamics of the sinter mix temperature during the technological stages of its preparation from pelleting to loading on pallets was studied, depending on a water temperature change during pelletizing. It was defined that for the winter working of the sinter department of JSC ``Ural Steel`` the water temperature increase which supplied of the pelletizer to moistening, for every 10°C, facilitates an increase in the temperature of the sinter mix on the pallets by 1.5-2.0°C. Therefore, for stable sinter mix production with a temperature higher than 55°C, it is necessary to supply a pelletizer with water, which temperature is at least 85°C. To implement the proposed technology, it is necessary to equip the sinter machines with water-heating recuperative heater, installed above the sintering machine behind the ignition hood and using heat, radiated from the surface of the sinter.
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    INFLUENCE OF Fe-Si-Mg-REM-INOCULANTS ON THE MICROSTRUCTURE OF IRON CASTINGS WITH VERMICULAR GRAPHITE
    (2022-01-01) Boldyrev D.; Nefedyef S.; Dema R.; Kharchenko M.; Chernyi S.; Suvorova E.; Mihailov E.; Latypov O.; Yordanova R.
    Complex additives, inherently, are not only inoculants, but also complex alloyed products having their own specific structure, whose influence on the crystallization processes of an alloy is actually not taken into account or studied. The work investigates inoculants made by two technologies. According to the first technology, an inoculant is made in the form of an ingot by crystallizing melt in a mold, according to the second technology, an inoculant is made in the form of an extra-thin ingot (0.5 - 3 mm thick plates) by continuous casting and freezing on water-cooled molds (drums). A phase electron and X-ray spectral analysis of the inoculants’ structure are carried out to produce vermicular graphite iron. Thus, the paper presents a research on the microstructure of CGI castings “Countershaft” molded in a ladle with the use of inoculants and describes specific features of their influence
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    Modeling of the thermal state of a hot rolled strip in an accelerated cooling process Part 2: A calculation of the thermal field of the strip. Results and conclusions
    (2020-01-01) Koldin A.; Dema R.; Nalimova M.; Shapovalov A.; Mihailov E.
    The physical and mathematical model of cooling a moving steel strip by a water jet system is described in Part 1 of this paper. The temperature distribution along the steel strip motion direction and at its cross section is obtained. Two main variants of the relative position of the upper and the lower jets are considered. An analysis of the jets pattern effect on the steel strip temperature field is performed. The validity of the heat transfer mathematical model and the program for calculating the temperature field is verified by comparing the results of the functioning Hot Rolling Mill 2000 of the Public Joint-Stock Company «Magnitogorsk Iron and Steel Works» with the calculated data referring to a specific steel grade. The transverse temperature distributions for different layouts of the jets as well as the longitudinal distributions of the maximum temperature differences of the steel strip sections are obtained. Results referring to the steel strip temperature field calculation in view of the temperature dependence of the thermo-physical properties of low-carbon steel are presented in this communication. Conclusions on the need of considering the temperature dependence of the steel thermo-physical properties when predicting the final temperature are drawn based on these calculations.
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    Modeling of the thermal state of the hot rolled strip in the accelerated cooling process part I: Heat transfer model
    (2019-01-01) Koldin A.; Dema R.; Nalimova M.; Mihailov E.; Shapovalov A.; Kharchenko M.
    This article presents a solution to the problem of determining the local heat flux density during cooling of a high temperature surface with a water jet. The solution takes into account the flow rate of the water jet and the diameter in the conditions of a transient boiling fluid. A local physic-mathematical model of moving strip's laminar cooling on a discharge roller table was compiled. Regions of jet impingement, film boiling, convective and radiative cooling in air are considered in this model.
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    The electron-microscopic and X-ray spectral analysis of phase composition of CGI inoculant structure
    (2019-01-01) Boldyrev D.; Shapovalov A.; Nefedyef S.; Dema R.; Kononov V.; Kharchenko M.; Suvorova E.; Markova I.
    The paper presents an analysis of both the phase and chemical compositions as well as the structure of 3 types of inoculants having a similar chemical composition but produced by two completely different technological processes. All investigated inoculants serve to produce vermicular graphite iron of a similar chemical composition. A qualitative identification of inoculant particles phase composition and surface microanalysis is carried out by electron-microscopic examination and X-ray spectral microanalysis. The investigations used can serve as an effective way of inoculants ranking according to their qualitative and performance characteristics.