SOLIDIFICATION MODELING OF MICROSTRUCTURE IN TWIN-ROLLER THIN STRIP CASTING OF STAINLESS-STEELS

The influence of process parameters on the dendritic microstructure of thin strips cast by the twin-roll method is analyzed in the framework of a one-dimensional solidification model and compared with experimen tal results. As a relevant characteristic the secondary dendrite arm s pacing lambda2 as a function of the distance x from the roll surface i s investigated. The difference between the local dendrite arm spacing near the strip surface and the strip centre, respectively, increases w ith the strip thickness and only depends on the casting temperature to a small extent. An increase in the strip/roller heat transfer coeffic ient due to a rising casting velocity or possibly enhanced roll-separa ting forces leads to a decrease in the dendrite arm spacing. The effec t of a sudden decrease in heat transfer during the solidification proc ess, on the lambda2(X) characteristics, e.g. by a local separation of the solidified shell from the roller surface, is discussed.