ANALYSIS OF COUPLED TURBULENT FLOW AND SOLIDIFICATION IN THE WEDGE-SHAPED POOL WITH DIFFERENT NOZZLES DURING TWIN-ROLL STRIP CASTING

Abstract

In the twin-roll continuous casting (CC) process that produces a near-net-shaped strip, the mushy zone solidification phenomena are mainly influenced by various process parameters such as nozzle shape, roll-gap thickness, and superheat of melt. This study numerically examines, in a wedge-shaped pool for the twin-roll CC process, the dependence of the solidification phenomena and melt-flow behavior on those process parameters. The turbulent characteristics of the melt flow are considered using a low-Reynolds-number k- k turbulence model. The results show that there exists the distinct region with a well-mixed melt flow and a wide range of mush in the lower part of the pool. The variation of the melt-flow velocity due to different nozzle types mainly affects the liquidus line and has little effect on the solidus line in the outlet region. In the case of a small roll gap, the liquidus line is shifted upward and the solidified shell thickness increases slightly in the outlet region. The variation of melt superheat mainly affects the position of the liquidus line. The direct melt feed onto the free surface has little effect of the melt superheat on an increase in the temperature in the lower part of the pool, while the overall temperature in the lower part of the pool for the submerged nozzle has a high dependence on the melt superheat.