Methods for casting stainless steel and articles prepared therefrom

Abstract

A process for casting stainless steel including forming an erodable casting mold, delivering molten stainless steel into the erodable mold, contacting the erodable mold with a solvent, cooling the molten stainless steel to at least partially solidify the stainless steel and form a casting. Stainless steel castings are also provided.

1 . A process for casting stainless steel, said process comprising forming an erodable casting mold, delivering molten stainless steel into the erodable mold, contacting the erodable mold with a solvent and cooling the molten stainless steel to at least partially solidify the stainless steel and form a casting. 
   
   
       2 . The process of  claim 1  wherein forming an erodable casting mold comprises obtaining a pattern and applying an erodable aggregate material to the pattern. 
   
   
       3 . The process of  claim 2  wherein the pattern is for a blade. 
   
   
       4 . The process of  claim 3 , wherein the blade is a turbine blade. 
   
   
       5 . The process of  claim 2 , wherein the pattern is reusable. 
   
   
       6 . The process of  claim 2 , wherein the pattern is a lost pattern. 
   
   
       7 . The process of  claim 6  wherein the lost pattern comprises a material selected from the group consisting of foam, wax, frozen mercury and frozen water. 
   
   
       8 . The process of  claim 7  wherein the lost pattern comprises foam. 
   
   
       9 . The process of  claim 6  wherein the lost pattern is coated. 
   
   
       10 . The process of  claim 9  wherein the coating is a ceramic coating. 
   
   
       11 . The process of  claim 2  wherein the erodable aggregate material is applied to the pattern by packing the erodable material around the pattern or by coating the erodable material onto the pattern. 
   
   
       12 . The process of  claim 2  wherein the erodable aggregate material comprises a particulate material and a binder. 
   
   
       13 . The process of  claim 12  wherein the particulate material is selected from the group consisting of crushed pumice, silica sand, ceramic, glass, volcanic glass, refractory micro-bubbles, cenospheres and mixtures of the foregoing. 
   
   
       14 . The process of  claim 13  wherein the binder comprises materials selected from the group consisting of phosphate glass, inorganic silicates, borates and magnesium sulfate. 
   
   
       15 . The process of  claim 12 , wherein the binder is present from about 5 percent by weight to about 15 percent by weight and the particulate material is present from about 85 to about 95 percent by weight, based on the total weight of the aggregate erodable material. 
   
   
       16 . The process of  claim 6  wherein the mold comprises a backing to support the erodable mold. 
   
   
       17 . The process of  claim 16  wherein the backing material is an erodable backing material. 
   
   
       18 . The process of  claim 17 , wherein the erodable backing is applied to an erodable mold, such as by packing the erodable backing around the erodable mold. 
   
   
       19 . The process of  claim 17  wherein erodable backing comprises a particulate material and a binder. 
   
   
       20 . The process of  claim 19  wherein the particulate material comprises a material selected from the group consisting of crushed pumice, silica sand, ceramic, glass, volcanic glass, refractory micro-bubbles, cenospheres and mixtures of the foregoing. 
   
   
       21 . The process of  claim 19  wherein the binder comprises a material selected from the group consisting of phosphate glass, inorganic silicates, borates and magnesium sulfate. 
   
   
       22 . The process of  claim 1  wherein the solvent contacts the erodable mold by spraying the solvent on the erodable mold or by immersing the erodable mold in the contacting solvent. 
   
   
       23 . The process of  claim 1  wherein the contacting solvent comprises water. 
   
   
       24 . The process of  claim 22  wherein multiple nozzles are used to spray the solvent on the erodable mold. 
   
   
       25 . A stainless steel casting obtained by the process comprising forming an erodable casting mold, delivering molten stainless steel into the erodable mold, contacting the erodable mold with a solvent, cooling the molten stainless steel to at least partially solidify the stainless steel and form a casting. 
   
   
       26 . The stainless steel casting of  claim 25  wherein the stainless steel has a fine microstructure comprising grain sizes having an average diameter of 50 μm or less. 
   
   
       27 . The stainless steel casting of  claim 26  wherein the average diameter for the grain sizes is in the range of from about 20 μm to about 50 μm. 
   
   
       28 . The stainless steel casting of  claim 25  wherein the casting is a blade. 
   
   
       29 . The stainless steel casting of  claim 28  wherein the blade is a turbine blade. 
   
   
       30 . The stainless steel casting of  claim 25  wherein the turbine blade is a stationary turbine blade or a rotating turbine blade.