Processes of structure formation in large steel castings
Processy litʹâ, 2021, Tom 144, №2, p.3-11
DOI:
https://doi.org/10.15407/plit2021.02.003Keywords:
steel ingot, crystallization, structure, convection, heat and mass transferAbstract
Received 07.05.2021
UDK 669.14:620.18
The results of physical modeling of the processes that occur in large steel ingots during solidification are presented. The regularities of the distribution of convective flows and temperature fields in the ingot are studied. The dependences of the values of heat flow from the ingot to the mold, the rates of crystallization, and movement of the two-phase zone of the solidifying alloy on the intensity of convective flows are established. It is proved the decisive importance of the convective movement of the melt on the unevenness of the solidifying metal crust along with the height of the ingots. It is shown that with a slight decrease in the temperature of the solidifying melt the thickness of the crust increases by 2.4 times. If convection of the melt along the height of the ingot is excluded, the parameters of its solidification (crust thickness, solidification coefficient, and crystallization rate) have the same values over the entire height. In this case, the temperature gradient in the solidifying alloy changes only in the direction from the side heat-removing faces to the axis of the ingot. It is found that convection of the solidifying melt is the main reason for the formation of a zone with increased viscosity in the bottom of the ingots in which a cone of nonmetallic inclusions deposits is formed. Also, the convective movement of liquid metal increases the intensity of heat transfer processes in solidifying ingots due to the increase in rates of crystallization and structural transformations. For different cooling modes, the parameters of the solidification process of the studied ingots were determined as well as the influence of convection on the formation of ingots structure.
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Copyright (c) 2021 А. В. Нарівський, А. С. Нурадінов, В. П. Школяренко, Г. О. Антонов, І. А. Нурадінов
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