PURPOSE: To prevent the development of crack on the cast billet surface by repeating the steps for stopping the cast billet drawing till the time, of which the molten metal surface is ascended to the prescribed to the prescribed height and for drawing continuously over the specific height at the specific speed.
CONSTITUTION: The molten metal melted by electron beam melting method is introduced into a water cooling mold 4, and while solidifying the molten metal in the mold 4, the solidified cast billet is drawn. In this casting method, the step for stopping the cast billet drawing till the time, of which the molten metal surface in the mold 4 is reached as ascending to the prescribed height, and the step for drawing continuously the cast billet over the 1W40mm height at ≥0.3mm/sec speed are repeatedly executed. In this way, the development of crack on the cast billet surface is prevented.
ONOE TOSHIO
KANAYAMA HIROSHI
MURAOKA TETSUHIRO
