抄録
It has been considered that products with particular crystal structures, such as unidirectionally solidified columnar grains, a single crystal and an in-situ composite eutectic structure, can be manufactured with an upward continuous casting process. In this work, after surveying various upward continuous casting processes reported in the literature, a moldless one was selected. An apparatus for this process was constructed, and trial experiments with Al were performed. The producing conditions of aluminum rods by the apparatus were investigated. The temperature distribution along the cast strand was measured by a thermocouple attached to the tip of the dummy bar. The structure and the surface conditions of the cast strands were examined. The temperature measurement showed that the solidification front of the cast strand located 10∼25 mm above the surface of the molten metal. The growth direction of the columnar grain of the cast strand showed that the configuration of the solidification front of the cast strand was flat or slightly convex. The diameter of the cast strand was determined by the temperature of the molten metal, the intensity of the cooling, and the speed of the upward withdrawing. Cast strands with plus tapers (growing bigger) were obtained at lower temperatures, more intensities and lower speeds. The structure of the dummy bar affected that of the cast strand. The cast strand was composed of columnar crystals solidified completely unidirectionally. Surface conditions of the cast strand were better at lower rotation speeds of cast strand, higher temperatures of molten metal and higher speeds of upward withdrawing.
