The heat transfer coefficient between cast and mold may have a strong influence on the solidification process. It is, therefore, important to correctly evaluate the heat transfer coefficient, by considering all factors relevant for its evolution, such as mold coating, air-gap formation, contact pressure, and thermomechanical behavior of the cast. In the present paper, the simulation of the solidification process coupled with the analysis of the thermal contraction of the cast is carried out with the aid of the finite element software V-Shrink, developed under the VCAD System Research Program. The results obtained confirm that proper evaluation of the heat transfer coefficient has a major effect on the temperature history, and consequently on the distribution of the local solidification times, and on the prediction of shrinkage porosity. Furthermore, the simulation results point out the considerable role played by the constitutive modeling of the cast material on the development of air gaps and hence on the heat transfer between the cast and mold.

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  Liquid phase may or may not be present on the casting surface during solidification. If present, it may cause various casting surface defects. Based on the Schwartz equation of solidification of metal in mold, an equation of surface temperature of alloy castings poured without superheat is introduced. Wetness index is deduced from the equation with which it can be judged if liquid phase is present or not on the casting surface. An equation is proposed to estimate how much superheat can further be raised until the liquid phase appears on the casting surface. Usefulness of the equation is demonstrated by comparing it with the numerical calculation of a series of iron base alloys and an aluminum alloy. The effects of various thermal parameters, in particular solidification temperature range of alloys, on the wetness of casting surface are discussed.

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  The shrinkage formation of Ductile Cast Iron (DCI) is studied by using computer simulations in consideration of various functions during the solidification process.
  Influence of thermal expansion ratio of the molding sand on appearance of open shrinkage during solidification of DCI (in riserless design) is studied by using artificial, and natural sand.
  The test result shows that lower expansion ratio of sand increase the volume of open shrinkage. Mixed use of silica sand and artificial sand which has low expansion ratio is proposed to reduce the volume of open shrinkage.

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  This study describes the resistance to oxidation of a hot-dip aluminium coated (aluminized) cast iron layer on an as-cast iron surface and the changes in the properties of the Fe-Al alloy layer by heating test.
  The weight increase of aluminized specimens during heating tests conducted in an oxidation atmosphere was lower than that of non-aluminized cast iron, indicating that resistance to oxidation of cast iron was improved by aluminization treatment.
  The thickness of the Fe-Al intermetallic layer consisting of mainly Fe₂Al₅ formed by aluminization treatment increased when high temperature was maintained by diffusion between the aluminum surface and cast iron. The composition of the grown alloy layer after maintaining the temperature at 1073K was mainly Fe₂Al₅. Complex phases consisting of Fe₂Al₅, FeAl, Fe₃Al, and Fe₃AlC_0.5 were formed in alloy layers after maintaining the temperature at 1273K.

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