| In this paper, according to the transient characteristics of vertical semi-continuouscasting, a mathematical model of flow, heat transfer and solidification process in slab isestablished using the MiLE method. An extra thick slab with a cross-section of900mm×2800mm is modeled, and the drawing process and subsequent solidificationprocess of semi-continuous casting are simulated to obtain the flow field, temperaturedistribution and solidification process in different time. The flow regularity of themolten steel in mold during pouring and the temperature distribution and thesolidification conditions of slab in different time during casting are analyzed. Theaffects of different process parameters on the thickness of billet shell and the largestheight of the semi-solid liquid core are calculated. The results show that:(1) The process of throwing is a quasi-steady state. The temperature andsolidification fraction of different locations in the slab hardly vary with time. Thethickness of billet shell increases gradually along the drawing direction. Some processparameters, such as the grille, the opening time of water switch in secondary coolingzone, the degree of superheat, the number of nozzles and the cooling conditions to theend of slab, have a little influence on the temperature distribution and solidificationprocess.(2) The casting speed has a great influence on the solidification process of verticalsemi-continuous casting: the slower the casting speed, the lower the largest height of thesemi-solid liquid core, which is benefit to feeding of the slab during solidificationperiod. The largest height of the semi-solid liquid core can be obviously reduced ifcasting with a steel material which has a smaller difference between solidus andliquidus, and thus solidification feeding can be easily realized and shrinkage andporosity can be eliminated.(3) The larger the cross section, the higher the largest height of the semi-solid liquid core, and thus the more difficult the solidification feeding. |
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