Determination of the Heat Transfer Coefficient at the Metal-Mold Interface During Centrifugal Casting

The heat transfer coefficient at the metal-mold interface (h _MM) has been determined for the first time during the centrifugal casting of a Fe-C alloy tube using the inverse solution method. To apply this method, a centrifugal casting experiment was carried out to measure cooling curves within the tube wall under a mold rotation speed of 900 rpm, imposing a centrifugal force 106 times as large as the gravity force (106 G). As part of the solution method, a comprehensive heat transfer model of the centrifugal casting was also developed and coupled to an optimization algorithm. Finally, the evolution of h _MM with time that gives the minimum squared error between measured and calculated cooling curves was obtained. The determined h _MM is approximately 870 W m⁻² K⁻¹ immediately after melt pouring, decreasing to about 50 W m⁻² K⁻¹ when the average temperature of the tube is ~973 K (700 °C), after the end of solidification. Despite the existence of a centrifugal force that could enhance the metal-mold contact, these values are lower than those generally reported for static molds with or without an insulating coating at the mold inner surface. The implemented model shows that the heat loss by radiation is dominant over that by convection at the tube inner surface, causing the formation of a solidification front that meets another front coming from the outer surface of the tube.