Papers by Author: Er Jun Guo

Abstract: Forced cooling measures need to be adopted in order to ensure the thick walled ductile iron casting solidification within the stipulated time. In this paper, the thick walled ductile iron casting for spent-nuclear-fuel container is used as the research object. The technology of outside mold has been identified in the actual production process. Through physical simulation experiment, the thickness of the outside the chills can be determined, and the cooling effect of chills is verified. The results show that cooling conditions have a decisive effect on the eutectic solidification, the residence time of eutectic platform and the time of casting solidification.

Abstract: A commercial software, MAGMASOFT, was used to simulate the ZM5 shell with different materials of chills. The calculated results of solidification are obtained. Shrinkage porosity is predicted by means of a built-in porosity criterion. It shows that using the different materials of chills, such as copper, gray iron and steel, a large amount of shrinkage porosity defects are formed in ZM5 shell. However, with graphite as the material of chills, shrinkage porosity defects of ZM5 shell can be effectively reduced.

Abstract: Application of spheroidal graphite cast iron in the production of spent-nuclear-fuel container contributes to improve the strength and toughness of the casting, because of the nodular shape of graphite. For a large-scale container, a forced-chilling technique is used to accelerate solidification process and raise spheroidization rate. In this paper, modeling of heat transfer in the container is performed. Influences of cooling media, inflow flux of coolant and thickness of sand layer upon the variations of cooling rate are systematically analyzed. Calculated results indicate that water as a coolant is more capable of enhancing the cooling course than air. Increasing inflow flux conducts an effective cooling job, whose influence is more apparent for air-cooling than for water-cooling. The role of decreasing the thickness of sand layer is most pronounced for raising solidification rate. The predicted cooling curves are compared with experimental measurements to validate the model.