PURPOSE: To obtain a clean steel having satisfactory surface quality by pouring a molten steel from the bottom into a casting mold in a vacuum atmosphere and continuing degassing with steam droplets in an intermediate vessel during the entire period thereof.
CONSTITUTION: A molten steel is poured into an intermediate vessel 2 in the upper part of a pouring pipe 3 and the pouring flow thereof forms steam droplets as the inside of the vessel 2 is communicated with a vacuum suction pipe 7 so that the hydrogen value conforming to the degree of vacuum and the temp. of the molten steel is obtd. with the highest degassing efficiency. The inside of a casting mold 4 is also communicated with the same vacuum suction pipe 7 and therefore the molten steel subjected to the degassing with steam droplets is cast by bottom pouring in an oxidation-free state into the mold 4 maintained in vacuum. The degassing with steam droplets of the molten steel is made possible over the entire period of casting in the above-mentioned way. The molten steel level in the mold 4 right after the leakage when the casting is completed is maintained equal to the molten steel level in the pipe 3 even during the charging without fluctuation and the casting defect occurring in such fluctuation is obviated.
NANBA AKIHIKO
MINO HIROYUKI
OOMORI TAKASHI
KOJIMA SHINJI
HIRATA KENJI
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