Three aspects of the production of a thin-wall test casting are discussed: mold filling, solidification and carbide formation.The mold-filling sequence of the test casting has been observed by pouring ductile cast iron behind a heat-resistant window. The simulated mold-filling behavior is in line with the experimental one. Very large temperature differences arise during thefilling stage. The temperature history during filling in the 3-mm (0.12-in.) plate has a decisive influence on the subsequent solidification. Simulation of the solidification in a thinwall casting has very little practical value without the use of areliable mold-filling calculation.The nucleation model, which allows to predict the experimental nodule counts at various locations in the test casting, is discussed. The model has been validated by means of experimental grain counts in lamellar and spheroidal graphite cylindricalcastings, which were obtained out of one melt and one inoculation treatment The grain count distribution reveals that a single distribution of heterogeneous substrates allows to model both the eutectic cell count and the nodule count, simultaneously. Anequation for the size of the substrates is derived. It allows to estimate the size of the substrates to be in the order of 10nm.The influence of silicon content and nodule count on the presence of carbides has been determined by experiment It reveals that a minimum silicon content is necessary in order to produce carbide-free thin-wall ductile iron castings. The reason for this is explained. Metallographic examination of carbides in 2-mm (0.8-in.)plate castings shows that carbides nucleate at the mold wall and grow into the casting as slender rays.
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