PURPOSE: To continuously and stably produce the half solidified metal by preventing the excessive growth of a solidified shell by the heat extracting heat flow flux of a cooling plate and the shearing strain rate of a solid-liquid boundary, thereby preventing an increase in the torque of a stirrer at the time of cooling molten metal under rotation of this stirrer.
CONSTITUTION: The half solidified metal is produced by cooling the molten metal injected into a cylindrical cooling vessel having the cooling plate from the upper part of this vessel under rotation of the stirrer. The excessive growth of the solidified shell is prevented by the heat extracting heat flow flux of the cooling plate and the shearing strain rate of the solid-liquid boundary, by which the increase in the torque of the stirrer is prevented. The relation between the heat extracting heat flow flux of the cooling plate and the shearing strain rate of the solid-liquid boundary satisfies the inequality. The inequality γ>12.9(m2/kcal).q, where γ: the shearing strain rate (s-1) of the solid-liquid boundary, q: the heat extracting heat flow flux (kcal/m2.s) of the cooling liquid. As a result, the increase in the torque generated in the stirrer is prevented and the half solidified metal having fine primary crystal grains and high solid phase rate is continuously and stably produced.
NIIDE TSUKASA
HIRONAKA KAZUSATO
TAKAHASHI HIROYOSHI
NANBA AKIHIKO
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