Local heat treatment for improved fatigue resistance in turbine components

Abstract

A method for locally heat-treating a gas turbine engine superalloy article to improve resistance to strain-induced fatigue of the article is disclosed. The method comprises providing a gas turbine engine superalloy article having a gamma prime solvus temperature; and locally over aging only a selected portion of the article to locally improve fatigue resistance at the selected portion of the article, wherein the local over age cycle includes heating at about 843° C. for about 3 to 4 hours.

1 - 11 . (canceled) 
   
   
       12 . The article of  claim 13 , wherein the superalloy has a nominal composition in weight percent of 20.5Co, 11Cr, 3.7Mo, 2.0 W, 3.4Al, 3.6Ti, 0.9 Nb, 2.4 Ta, 0.05Zr, 0.04C, 0.03 B, balance Ni or a nominal composition in weight percent of 8Co, 14Cr, 3.5 Mo, 3.5W, 3.5Al, 2.5Ti, 3.5 Nb, 0.15C, 0.01 B, balance Ni or a nominal composition in weight percent of 20Co, 11Cr, 3.7Mo, 2.0 W, 3.4Al, 3.6Ti, 0.9 Nb, 2.1 Ta, 0.05Zr, 0.04C, 0.03 B, balance Ni. 
   
   
       13 . An article comprising a gamma-prime precipitation strengthened superalloy;
 wherein substantially all of the article exhibits a grain structure associated with a common heat treatment history including heating the entire article above a gamma prime solvus temperature followed by quenching and aging at a final age temperature below the gamma prime solvus temperature; and   wherein at least a local region of the article exhibits an improved fatigue resistance due to local over aging at a temperature higher than the final age temperature and below the gamma prime solvus temperature, as compared to a fatigue resistance of a comparable article with a common heat treatment history without local over aging.   
   
   
       14 . The article according to  claim 13  comprising a component for a gas turbine engine. 
   
   
       15 . The article according to  claim 14  wherein the gas turbine engine component is a disk having an outer rim portion and a hub portion connected by a web portion, wherein the hub portion defines a central bore, and wherein the local region includes the hub portion. 
   
   
       16 . The article according to  claim 14  wherein the component for the gas turbine engine is at least one member selected from a disk, a seal, and a shaft. 
   
   
       17 . The article according to  claim 13  wherein the superalloy is at least one member selected from a nickel base superalloy, a iron base superalloy, and a nickel-iron base superalloy. 
   
   
       18 . The article according to  claim 13 , wherein the article includes a flange region defining a bolt hole, and wherein the local region includes the flange region.