Кафедра матеріалознавства та термічної обробки металів (ДМетІ)

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UK: Кафедра матеріалознавства та термічної обробки металів (Дніпровський металургійний інститут, ДМетІ) EN: Department of Material Science and Heat Treatment of Metals (Dnipro Metallurgical Institute, DMetI)

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    Regularities in the Formation of the Structure and Mechanical Properties of Gray Cast Iron Depending on the Cooling Conditions and Cross-Section of Castings
    (Iron and Steel Institute of Z. I. Nekrasov National Academy of Sciences of Ukraine, Dnipro, 2026) Karpova, Tetiana P.; Hryhorieva, N. O.
    ENG: Gray cast iron is one of the basic casting materials in industry, widely used for the manufacture of parts for automotive, machine-building and railway equipment due to the combination of high casting properties, satisfactory mechanical characteristics and relatively low cost. In the context of increasing costs of primary raw materials and increased requirements for resource efficiency, the technology of smelting synthetic gray cast iron using steel scrap in induction furnaces is becoming increasingly widespread. Along with technological advantages, this approach determines the specific features of the formation of the microstructure of castings, especially in the presence of variable cooling conditions. One of the key factors determining the structure and properties of synthetic gray cast iron is the cross-section of castings, which directly affects the rate of heat removal during crystallization and subsequent cooling. Non-uniformity of thermal conditions can lead to changes in the dispersion of the pearlite matrix, the morphology of graphite inclusions and, as a result, to variations in the mechanical properties of the material. The complex of studies included Brinell hardness control, determination of tensile strength, and metallographic analysis. It was established that the microstructure of the studied material is represented by a pearlite matrix with lamellar graphite and finely dispersed phosphide eutectic. It was shown that an increase in the cross-section of the casting is accompanied by a decrease in the cooling rate, which is manifested in a decrease in the homogeneity of the pearlite matrix and an increase in the size of graphite cells. It was found that larger graphite inclusions contribute to a decrease in the tensile strength due to stress concentration, while the hardness level is determined mainly by the state of the pearlite matrix and the chemical composition of the alloy. The results obtained are of practical importance for optimizing the technological modes of casting synthetic gray cast iron, in particular when designing parts of different cross-sections and selecting cooling conditions in order to ensure a given set of mechanical properties.