| 摘要 |
<p>PURPOSE:To make the qualities of surface and inner part in a cast ingot good and to reduce cut-off quantity by making the specific inert gas atmosphere in a tank at the time of casting, using covering powder and executing the casting. CONSTITUTION:Raw material is charged into a vacuum induction melting furnace set in the tank and melted under vacuum or reduced pressure inert gas atmosphere. At the time of tapping molten metal, the pressure in the tank is made under the inert gas atmosphere having 400Torr and also beforehand the covering powder in the mold is set. The tapping under this condition is started and the molten metal of the molten steel, etc., is supplied into the mold and while covering the molten metal surface with the covering powder and while inserting the powder between the molten metal and inner face of the mold, the molten metal is gradually supplied in the mold. By this method, entrapment of the covering powder does not occur and the development of blow hole at the powder sticking part is eliminated and the coating film on the molten metal surface is good and the surface of ingot after casting is made good.</p> |
