Abstract: A process for casting a turbine wheel includes steps of identifying a metal composition from which the turbine wheel is to be cast, providing a mold that defines a cavity into which molten metal composition is to be poured for casting the wheel, providing a seed member made of the metal composition and having an equiaxed grain structure, disposing at least a portion of the seed member within the cavity of the mold, pouring the molten metal composition into the cavity such that the molten metal composition envelops the portion of the seed member within the cavity, and controlling the process so that the portion of the seed member at least partially melts through contact with the molten metal composition and so that, upon cooling, the metal composition around the seed member solidifies with an equiaxed grain structure as precipitated by the equiaxed grain structure of the seed member.

Abstract: A process for casting a turbine wheel includes steps of identifying a metal composition from which the turbine wheel is to be cast, providing a mold that defines a cavity into which molten metal composition is to be poured for casting the wheel, providing a seed member made of the metal composition and having an equiaxed grain structure, disposing at least a portion of the seed member within the cavity of the mold, pouring the molten metal composition into the cavity such that the molten metal composition envelopes the portion of the seed member within the cavity, and controlling the process so that the portion of the seed member at least partially melts through contact with the molten metal composition and so that, upon cooling, the metal composition around the seed member solidifies with an equiaxed grain structure as precipitated by the equiaxed grain structure of the seed member.

Abstract: A process for making a turbine rotor includes steps of providing a shaft made of a first metal composition and having an integral pin projecting axially therefrom, providing a mold that defines a cavity for investment casting a turbine wheel, disposing the pin within the cavity of the mold, pre-heating the mold and the pin to a mold temperature, pouring a molten second metal composition into the cavity of the pre-heated mold such that the molten second metal composition envelopes the pin within the cavity, and controlling the process so that the pin acts as a chill member causing the second metal composition around the chill member to solidify with a finer equiaxed grain structure than would be the case without the chill member. The turbine wheel is joined to the shaft via the casting of the turbine wheel about the pin.

Abstract: A method of casting an alloy is provided, comprising the steps of pouring molten alloy into a mould (18), moving the mould (18) to a first position inside a chamber (12), the chamber (12) including a volume of quenchant (16), increasing the pressure within the chamber (12), and moving the mould (18) to a second position in which at least a portion of the mould (18) is submersed in the quenchant (16), so as to reduce the temperature of the mould (18).

Abstract: A method of casting a molten metal into a mould uses an apparatus which has a casting chamber which includes a mould into which molten metal is introduced when the casting chamber is at least partially evacuated, to fill the mould, a tundish connected to the casting chamber, the tundish having an opening in register with an inlet aperture of the casting chamber to provide an inlet flow path for the molten metal from the tundish into the casting chamber, a plug which includes a sealing part of a material with a melting temperature not greater than the temperature of the metal being cast, the method including locating the plug to close the molten metal flow path, at least partially evacuating the casting chamber, pouring a volume of molten metal into the tundish sufficient to provide the casting, whereby at least the sealing part of the plug melts to permit molten metal to flow along the flow path into the casting chamber.

Abstract: A method of casting a molten metal into a mould uses an apparatus which has a casting chamber which includes a mould into which molten metal is introduced when the casting chamber is at least partially evacuated, to fill the mould, a tundish connected to the casting chamber, the tundish having an opening in register with an inlet aperture of the casting chamber to provide an inlet flow path for the molten metal from the tundish into the casting chamber, a plug which includes a sealing part of a material with a melting temperature not greater than the temperature of the metal being cast, the method including locating the plug to close the molten metal flow path, at least partially evacuating the casting chamber, pouring a volume of molten metal into the tundish sufficient to provide the casting, whereby at least the sealing part of the plug melts to permit molten metal to flow along the flow path into the casting chamber.