Heat transfer boundary conditions for the numerical simulation of the DC casting process

The temperature evolution during the start-up phase of the Direct Chill (DC) casting process is critical to the prediction of strain-stress evolution during solidification. The start-up phase of DC casting is complex, as heat is extracted by the mold, bottom block, and cooling water, while process parameters are ramped up to their steady state values. The modeling of DC casting involves making assumptions on the various heat transfer mechanisms, such as (a) direct contact of liquid metal and mold, (b) air gap between mold and ingot surface, (c) water cooling on rolling and end faces of the ingot, (d) ingot contact with the bottom block, and (e) water intrusion between the bottom block and ingot. The boundary conditions for the heat transfer analysis during the startup are discussed in detail. Numerical simulation results are presented for a typical casting run, including variable casting speed, metal head, and water flow rate.