| 摘要 |
PROBLEM TO BE SOLVED: To provide a degassing apparatus with which development of inclusions such as oxides is suppressed and impurity gas consisting essentially of gaseous hydrogen is sufficiently removed and molten metal with reduced impurities can be obtained, to provide a degassing method using this apparatus by which a cast product scarcely developing internal defects, scarcely leaving the inclusions and having excellent mechanical strength can be produced at a lower cost than by the conventional method. SOLUTION: In the degassing apparatus having a means with which gas for degassing is blown into the molten metal and stirred by rotating an impeller to diffuse this gas into the molten metal, the thickness of the impeller 2 is made as thin as possible and the shape of the impeller 2 is formed so that the bubbles of the gas for degassing are easily divided into finer bubblers. Further, the diameter of a shaft 1 is made as small as possible while maintaining sufficient strength to rotate the impeller 2, and a suitable and not excessive amount of gas for degassing is diffused by rotating the impeller 2 having a suitable and not excessive number of rotational while suppressing the disturbance of the molten metal surface by intensive stirring even the molten metal so that finer gas bubbles for degassing are filled in the molten metal.
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