A NOVEL TECHNIQUE FOR MELTING AND CASTING SUPERALLOYS

摘要

Superalloys are traditionally melted and cast under vacuum to eliminate the formation of inclusions in the casting that can reduce their mechanical properties. Counter-gravity Low-pressure Inert-gas (CLI) process is a unique method of melting and casting superalloys under inert atmosphere which precludes the use of vacuum during the melting and casting process. In addition, the CLI casting process fills the mold through a single-use fill pipe inserted into the center of the melt thus avoiding the oxides that often congregate along the periphery of the molten alloy. A strict inert atmosphere control during the CLI melting process ensures a very low level of molten alloy contamination. Oxygen levels of under 50 ppm are typically maintained during CLI melting and casting. Resultant gas content in the casting is typically less than 50 ppm oxygen and nitrogen. Such low levels of oxygen and nitrogen do not adversely impact the mechanical properties.