Process for casting columnar grain airfoil with preferential primary orientation

Abstract

A molding process utilizes a seed with a columnar grain structure for defining a desired grain structure in a completed casting. The seed is received within a seed cavity of a mold. The molten material adopts the orientation of the columns defined within the seed during solidification to form a completed molded article having a desired columnar grain structure.

What is claimed is: 
     
         1 . A mold assembly for fabricating a cast article, the mold assembly comprising:
 a mold cavity including a shape defining a desired geometry of a cast article and a bottom opening including a width;   a seed cavity in communication with the mold cavity for receiving a seed, the seed cavity including width substantially equal to the bottom opening;   a seed receivable within the seed cavity, the seed including a defined columnar grain orientation for adoption within the molded article.   
     
     
         2 . The assembly as recited in  claim 1 , wherein the seed comprises a material identical to molten material utilized for fabricating the molded article. 
     
     
         3 . The assembly as recited in  claim 1 , wherein the seed comprises one of a metallic material and a composite material different than the material utilized for fabricating the molded article. 
     
     
         4 . The assembly as recited in  claim 1 , wherein the seed comprises a vertical grain orientation parallel with a vertical axis through the mold cavity and a fixed rotational grain orientation along the column. 
     
     
         5 . The assembly as recited in  claim 1 , including a cooled plate for supporting the mold cavity within a heated chamber, wherein the cooled plate is movable in a controlled manner to remove the mold cavity to control solidification of molten material. 
     
     
         6 . A mold assembly for fabricating a cast article, the mold assembly comprising:
 a mold cavity including a shape defining a desired geometry of a cast article;   a seed cavity in communication with the mold cavity for receiving a seed;   a seed receivable within the seed cavity, the seed defining a plurality of columns each defining a primary grain orientation for defining a corresponding plurality of columnar grains within a molded article that include the primary grain orientations defined by the seed; and   a cooled plate for supporting the mold cavity within a heated chamber, wherein the cooled plate is movable in a controlled manner to remove the mold cavity to control solidification of molten material.   
     
     
         7 . The mold assembly for fabricating a cast article as recited in  claim 6 , including a baffle that separates the mold cavity from the seed cavity. 
     
     
         8 . The mold assembly for fabricating a cast article as recited in  claim 6 , wherein the mold cavity includes a top opening and a bottom opening, the bottom opening having a width substantially equal to a width of the seed cavity. 
     
     
         9 . The mold assembly for fabricating a cast article as recited in  claim 6 , wherein the mold cavity comprises several cavities that are in communication with each other through a common inlet for molten material. 
     
     
         10 . The mold assembly for fabricating a cast article as recited in  claim 9 , wherein each of the several cavities includes a corresponding seed cavity.