The centrifugal casting method is widely applied to the manufacture of rolling mill roll. It is roughly divided into vertical type, incline type, and horizontal type according to the angle of rotation axis. In this research, the influence of the rotation angle on the solidified structure of high chromium cast iron, which is a typical roll material, was studied. For the vertical type and large angle conditions, the dendrite grows, the columnar crystal region expands, and the inner segregation zone disappears. For the horizontal type and small angle conditions, the rotation force acts vertically in the direction of solidification to the molten metal and dendrite growth is suppressed. Segregation in the columnar crystal zone is also likely to occur. In low temperature casting, the influence of rotation angle on the solidification structure is small.

  The solidification microstructure of spheroidal graphite cast iron was analyzed by electron probe micro analysis (EPMA) and scanning transmission electron microscopy (STEM), focusing on the distribution of Cu. EPMA and STEM results clarified the following tendency in the distribution of Cu in spheroidal graphite cast iron containing Cu within the pearlite matrix : (1) Cu-Sn-Mg-enriched regions were distributed in the pearlite matrix, and (2) the distribution of metallic elements of Cu, Sn, and Mg in Cu-Sn-Mg enriched regions was not homogeneous, and a composite of metallic and oxide phases was formed. EPMA with a field-emission electron gun (FE-EPMA) and FE-STEM apparatus with a silicon drift detector were highly effective for clarifying the distribution of Cu, compared with conventional EPMA employing a thermionic-emission electron gun (TE). The high-resolution observation using FE-STEM, and the combination with TE-EPMA, FE-EPMA and FE-STEM, are powerful tools for clarifying the distribution of the Cu element in spheroidal graphite cast iron.

  The thickness accuracy of plate-shaped pure metal castings was experimentally evaluated, in which the effects of the rmal deformation of molds were also numerically investigated. The plate thickness of the castings made by sand mold casting decreased with the distance from the edge face despite the casting materials and/or casting conditions. The thickness accuracy of these castings could be evaluated using the accuracy index A/T (A : high thickness accuracy range, T : edge thickness), which enabled the quantitative comparison between different casting materials and/or different casting conditions. As a result, the lower the melting temperature, and the higher the superheat and/or mold temperature, the greater was A/T. The thermal stress analysis of the sand mold indicated that the thermal deformation of the mold was the main factor influencing those A/T values. On the other hand, the A/T values of pure tin castings might be greatly affected by thermal and/or solidification shrinkage. The numerical comparison with metal and graphite molds also indicated that the temperature difference caused inside the mold is the main factor influencing the thermal deformation of the mold cavity, and that the deformation is reduced by smaller thermal expansion coefficient and/or greater thermal conductivity (temperature diffusivity) of the mold.

  Die-casting is widely applied to the production of automotive components because of its high productivity for manufacturing complex-shaped castings. However, since molten metal is injected into a cavity at high speed and it solidifies rapidly under high pressure in this process, many casting defects are liable to occur. Although the most frequent internal defect is gas entrapment, shrinkage porosity also forms in the thick-wall portions of die castings. In order to avoid shrinkage porosity, there is a need to feed adequate molten metal to compensate the shrinkage volume during solidification. Therefore, it is desirable to better understand the feeding behaviors of molten metal under high pressure and rapid cooling conditions in the die casting process. In this study, the permeabilities of Al-Si alloys during the solidification process under die-casting conditions were determined by measuring the pressure transmission of the molten metal from the plunger to the mold cavity so as to obtain the feeding resistance coefficients. The formation of shrinkage porosities in die-castings was proven to be predictable by numerical simulation using the obtained feeding resistance coefficients.