1988 Volume 74 Issue 8 Pages 1609-1616
The molten steel poured into the water cooled copper mold was rapidly solidified by changing the filling time. From the measurement of the temperature change in the copper mold, heat flux was calculated. Temperature distribution in the copper mold was simulated and predicted, and the primary dendrite arm spacing was calculated by use of the dendrite growth theory. Heat flux in the copper mold increased with time and reached a maximum value and then decreased gradually due to the formation of the air gap. The shorter was the filling time into the copper mold, the greater was its maximum value. The reason for this is that Nusselt number as a function of Reynolds number increases and extractive rate of heat increases with decreasing of the filling time. Therefore, it is found that the shorter is the filling time, the thicker is the initial solidification layer and the finer is the microstructures. By the modeling of the dendrite arm spacing based on TRIVEDI'S growth theory, the arm spacing was found to be mainly influenced by the temperature gradient.
