Investigating kissing point location and solidification front in twin roll casting of steel through finite-element-based thermo-fluid models

Abstract

Making thin strips directly from the melt by twin roll casting requires precise control over process parameters to obtain defect-free components. Strategically controlling the kissing point location and the solidification front can mitigate the probability of crack formation. A two-dimensional low Reynolds number $k\text{–}\epsilon$ turbulence model is used to identify the location of kissing point for a vertical twin roll casting process. The temperature-dependent viscosity and apparent heat capacity method is employed to imitate the flow of melt and the solidification behaviour. The effect of different roll rotational speeds (20–28 rpm) and inlet melt temperatures (1733–1813 K) on solidified shell thickness and kissing point location is explored. The formation of a laminar sub-layer near the roll surface ensures uniform temperature distribution and high Nusselt number indicates dominant convective heat transfer from the upper roll surface. The shifting of the kissing point location is obvious by increasing roll rotational speed and inlet melt temperature accompanied by reduced solidified shell thickness. A polynomial relation between these parameters offers a practical solution for optimising heat transfer efficiency with direct applicability to industrial twin roll casting operations. This insightful study provides variation in kissing point location with process variables of twin roll casting confronting various dimensionless numbers.