2018 年 104 巻 6 号 p. 293-302
In order to investigate the possibility for control of macrosegregation by size and shape of equiaxed grains, laboratory scale casting experiments have been performed, using Al-10mass%Cu alloy. The mold was newly developed in order to produce macrosegregation, intentionally bringing about a bridging in the middle of a cast. Equiaxed grain size (d) was controlled by the amount of the modifier. The complexity of the equiaxed grain morphology was controlled by the mechanical vibration and was characterized using fractal dimension (Df). Macrosegregation was quantitatively characterized by the areal fraction of eutectic structure (fE). Multiple regression analysis for the maximum value of fE with respect to d and Df have been performed. It was found that the maximum of fE decreased with decreasing d and with increasing Df. Based on the multiple regression analysis, the concept of a size and shape map for macrosegregation free zone has been developed.
