چكيده به لاتين
Abstract:
Lost foam casting (LFC) process is privileged as it can provide simple molding practice, by elimination of cores and parting planes, proper dimensional accuracy and the adaptability with either customized or mass production. The In-mold method of adding spheroidizing agents to make ductile iron can also be comparatively more efficient, reduce the tendency to formation of carbides, increase the number of nodules and promote nodularity. To integrate the In-mold method with the LFC process, the spheroidizing agent was added in three quantities of 0.6, 0.8 and 1 wt.% of the total melt to produce test bars of 10, 20 and 30 mm diameters, and 200 mm height. The casting was carried out at two different temperatures of 1410 °C and 1440 °C. The bottom (near to gate), the middle and the top sections of the bar (the furthest distance from the gate) were then examined using optical microscopes. It was clearly evidenced co-presence of areas of spherical and non-spherical graphite at the different sections with decreasing the area ratio of non spherical graphite area by increasing both pouring temperature and the amount of spheroidizing agent. The average nodule count in the spherical graphite area in all the conditions was high. The improvement in graphite morphology in the spherical graphite area was attributed to the reduction in the pouring temperature. Details of the shape, size, and distribution of graphite in different sections has been reported. It seems the conditions for the dissolution of the spheroidizing material in different parts of the specimen is different. A possible pattern of reacted molten motion and the conditions of polystyrene foam evaporation are also discussed.
Keywords: Ductile cast iron, In mold lost foam process, Pouring temperature, Section thickness, Spheroidizing material, Graphite distribution, Polystyrene foam.