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Method and apparatus for controlling radial solidification in cast turbine wheel or nozzle assembly so as to produce an equiaxed fine grain structure in a hub portion and a directionally solidified grain structure in an integral blade portion by means of adjustable heat shields and heating elements

Method and apparatus for controlling radial solidification in cast turbine wheel or nozzle assembly so as to produce an equiaxed fine grain structure in a hub portion and a directionally solidified grain structure in an integral blade portion by means of adjustable heat shields and heating elements disposed above and below the mold.

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Apparatus for casting a turbine component having a central hub with a predominately equiaxed grain structure and radially outwardly extending blades with a predominately directionally solidified grain structure, comprising: a disk-shaped mold having an interior casting cavity defining said turbine c

Apparatus for casting a turbine component having a central hub with a predominately equiaxed grain structure and radially outwardly extending blades with a predominately directionally solidified grain structure, comprising: a disk-shaped mold having an interior casting cavity defining said turbine component including portions defining said central hub and said radially outwardly extending blades, a heat sink positioned around the outer periphery of said disk-shaped mold and adjacent said blade defining portion of said casting cavity, a top thermal shield positioned adjacent the top side surface of said disk-shaped mold, and a bottom thermal shield positioned adjacent the bottom side surface of said disk-shaped mold. A method of making a cast metal turbine component of the type having a central disk with integrally formed blades extending radially therefrom and lying generally in the plane of the disk, comprising the steps of: providing a disk-shaped mold having an interior casting cavity defining said turbine component, a cooled metal heat sink adjacent the periphery of said cavity, and heat shields adjacent the top and bottom side surfaces of the mold, casting molten metal into said mold, extracting heat from said molten metal through the peripheral heat sink while preventing substantial loss of heat from the top and bottom side surfaces of the mold, by utilizing said heat shields thereby forming a radial thermal gradient in said molten metal, and causing said molten metal to directionally solidify radially inwardly from said heat sink to form a columnar grain structure in at least the blade portion of the turbine component.