Effects of contents of carbon and silicon, and spheroidizing conditions such as amounts and kinds of additives and their treating temperatures on chilling tendency of spheroidal graphite irons cast in a metal mold 30mm in diameter were studied. When additives of 9.30%Mg-4.02%Ca- 2.72%RE-44.7%Si-Fe are used, eutectic carbides disappear at Si 2.6 to 2.7% (3.4 to 3.6%C) by reducing the amount of additives down to 0.4% and lowering the treating temperature down to 1,350°C. When treated at 1,400°C, low Mg additives of 3.14%Mg-1.13%Ca-1.6%RE-44.5%Si-Fe show lighter chilling tendency than the others at the same retained Mg. At carbon saturation values 1.07 to 1.09, low carbon irons of 3.1 to 3.3%C are free from eutectic carbides, but irons of about 3.6% have fine Ledeburites in spite of graphite nodules up to 1,750/mm². The chilling tendency of spheroidal graphite irons cast in metal molds depends not on the number of graphite nodules but on mainly spheroidizing temperatures and is moderated by suppressing the explosive reaction in treating.

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  A full-size container model for temporal storage and shipping of spent nuclear fuels from nuclear power plants was prepared to study the utilization of ductile cast iron. Various inspections of the model were carried out. A technique for manufacturing ductile cast iron containers for spent nuclear fuels superior in quality to those made in West Germany, “Cask” has been achieved.

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  Successful conditions of hot isostatic press were studied for stainless steel castings analytically and experimentally. Eliminating steps of internal voids through HIP can be simulated by introducing the relation between flow stress and strain rate and extending a cylindrical model by planer strain. HIP treating of castings in which internal voids are completely pressed and disappear has such a preferable effect that the fatigue strength increasses by 50% or more.

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  Solidification technology for orientation control of Ni-base superalloy single crystals was studied using NASA-IR 100 alloy. Crystal growth processes were analyzed both by numerical simulation using a two-dimensional heat flow model and actual casting experiments. The orientation of a single crystal strongly depends on the macroscopic crystal structure of the growth starter and is influenced little by the selector design. To obtain <100>-oriented single crystals, the starter must be of the columnar structure and grown vertically. A preferable starter structure is achieved by selecting a flat-faced chill as against that of a corrugated surface, preheating the mold at temperatures above or at least near the liquidus of the alloy, and pouring at temperatures above a certain limit. Single crystal round bars with axial orientation within 10 degrees from <100> orientation are successfully manufactured with a 100% yield.

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  Practical intake-manifolds and test plates of AC2B, AC4B and Al-Si alloys which are different in Si concentration were cast. The feedability of Al-Si and Al-Si-Cu alloys greatly varies with a change in Si content. The limit solid fraction of feeding (Lfs) of these alloys becomes smaller with an increase in Si content. The alloys having smaller Lfs are uncompensatory for solidification shrinkage in the early stage of solidification. When such an alloy containing higher Si as AC4B is cast, more of shrinkage porosity defects are generated. Alloys having greater Lfs are consequently easy to make defect free castings because of their compensation for solidiccation shrinkage until larger solid fraction.

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  Dissolution behavior of Fe-Si-Mg alloys through the “In-Mold” process was studied by inserting a set of sensitive electrodes in a reaction chamber. A test pattern was designed in such a manner that residual Mg can be analyzed in time sequences. Mechanical properties and microstructures of the processd iron were measured at different thicknesses. Changing the alloy mesh size results in changes in penetration of molten metal into the intergranular gap and hence the reaction surface area, thus alloy solution rate and casting homogeneity will be affeceted.

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