In order to produce near-net shape castings, it is important to predict the final shape by taking into account thermal shrinkage during the solidification and cooling processes and thermal deformation caused by uneven cooling. In this study, to accurately predict the final shape of castings using numerical analysis, we proposed a simple calculation method that takes into account the deformation of the sand mold before the start of solidification. Calculations and verification experiments using this method were performed on rotor-shaped ductile iron castings, and it was confirmed that the prediction accuracy of the final shape was improved by taking into consideration sand mold deformation before the casting formed a solidified shell. Particularly with rotor shapes, the difference in the amount of deformation between the peaks and valleys was found to be smaller than the predicted difference assuming that cooling is uniform.

  This study investigated the relationship between the type of cavities that occur in CE meter shell cups and the thermal analysis properties of spheroidal graphite cast iron molten metal.

  The cavities in shell cups were classified into three types : gas hole type cavity, massive type shrinkage cavity, and dispersion type shrinkage cavity. The timing of the occurrence of cavities was estimated from the diffusion of C around the holes. Results of the experiments revealed a high correlation between EGA (Eutectic Graphite Ability) and number of graphite grains. In addition, most of the samples with a large number of graphite grains showed gas hole cavity, and most of the samples with a small number of graphite grains showed dispersion type shrinkage cavity. Assuming that the occurrence of shrinkage cavity is determined by two factors : the amount of released gas that could no longer be dissolved and the negative pressure generated inside the casting, gas hole cavities can also be considered as a type of shrinkage cavity.

  As the pouring temperature (initial temperature T₀) increased, the shrinkage tendency θ (thermal conductivity near the thermocouple) became smaller and the solidification ending temperature T_s increased. Since pouring temperature affects thermal analysis parameters, it was assumed that the test must be performed at a constant pouring temperature or thermal analysis parameters must be adjusted according to the pouring temperature in the thermal analysis using a CE meter. As the number of graphite grains increased, the ratio of second half eutectic solidification time R_she (＝ (t_TS－t_TEM) / (t_TS－T_TSC)), which is obtained by dividing the second half eutectic solidification time by the total eutectic solidification time, increased and shrinkage tendency θ decreased. This indicates that the thermal conductivity near the thermocouple increased as the ratio of second half eutectic solidification time R_she increased. These findings suggest that the ratio of second half eutectic solidification time R_she, which indicates the amount of graphite crystallized in the second half of eutectic solidification, is important in the analysis of molten metal properties.

  This purpose of this study was to further enhance refine primary silicon in hypereutectic Al-Si alloys by adding AlP compounds which are heterogeneous nuclei of silicon, instead of adding phosphorus as normally done. The AlP-addition agent was an Al-700ppmP ribbon manufactured by the melt quenching method. The analysis of AlP compounds in normal gravity die castings and ribbon was conducted by SEM-EDS. The results showed the following ; (1) The AlP compounds in the Al-15%Si-70ppmP alloy gravity die castings added with phosphorus as normally done were 2μm in average size. (2) Those in the ribbon were 0.2μm in average size. (3) The number of AlP compounds in the ribbon was significantly large. Next, the refining effects of the ribbon were examined using Al-15%Si-5ppmP and Al-15%Si-15ppmP alloys. The experiments included melting of experimental alloys at 1053K, adding 8.5-17g of ribbon per 1kg of melts at 1023K, holding the melts for 10min to adjust the temperature to 1023K, and casting them into metallic dies using gravity casting. Comparison of normal Al-15%Si-70ppmP alloy gravity die castings and Al-15%Si-16ppmP alloy gravity die castings added with ribbon indicated the following : The average particle size of primary silicon in the former castings and in the latter castings were 14μm and 10μm, respectively. These results confirm that ribbons containing a large amount of fine AlP compounds are more effective as primary silicon refiner than conventional P-addition agents.