Thin strip casting of steel with a twin‐roll caster ‐ correlations between process parameters

Thin strip casting of steel according to Bessemer is now being investigated world‐wide in many institutions. In order to optimize, stabilize and scale up the process, a better understanding is needed. So there is a large interest in model descriptions. The best treatment by an exact analytical solution of the heat transfer equations is not possible due to its complexity. Instead, several numerical calculations have been carried out with good accuracy, but due to the large number of influencing parameters they are very often not generally applicable. The treatment in this paper is a compromise: the physical problems are solved by use of some approximations; thus analytical approaches with sufficient accuracy and general applicability are obtained. First the geometry of the pool and of the solidification is studied. An important result of this is that the pool must be treated in two different parts with strongly different heat transfer behaviour. In the upper part no solid bridges occur, and the rolling force cannot be transmitted. Thus the heat transfer into the rolls is hampered and can be described according to Newton. In the lower part there are solid material bridges to transmit the roll force, although a full solidification is not yet completed. The heat transfer into the rolls is much improved, and is now ideal. Then important process parameters as pool height, rolling force, and strip temperature are calculated and results are compared with data obtained from Fe6.3%Si experiments.