Treatment for preventing stress corrosion cracking

Abstract

A treatment for prevention of stress corrosion cracking (SCC) and a treated component are disclosed. A surface of a relatively high tensile strength component is heated to a temperature at which at least one of tempering or annealing occurs. The surface is then cooled in a controlled manner so as to maintain a reduced tensile strength at the surface that minimizes SCC while keeping a relatively high tensile strength in the remainder of the component.

1 . A method for treating a component to minimize stress corrosion cracking (SCC), comprising:
 heating a surface of a component to a temperature at which at least one of tempering or annealing occurs at the surface; and   cooling the component in a controlled manner so as to maintain a surface tensile strength that minimizes SCC, wherein the resultant surface tensile strength is lower than a resultant high tensile strength of a remainder of the component.   
     
     
         2 . The method of  claim 1 , wherein the heating includes induction heating. 
     
     
         3 . The method of  claim 1 , wherein the temperature is greater than 540 degrees Celsius. 
     
     
         4 . The method of  claim 1 , wherein the heating and cooling produce a full anneal of the surface. 
     
     
         5 . The method of  claim 1 , wherein the cooling includes:
 maintaining a heating apparatus in an operational position with respect to the component; and   adjusting the heating in a manner that causes the temperature in the surface to decrease along a desired thermal profile.   
     
     
         6 . The method of  claim 1 , wherein the component includes a generator component. 
     
     
         7 . The method of  claim 6 , wherein the component is selected from the group consisting of: a generator rotor or a generator retaining ring. 
     
     
         8 . The method of  claim 1 , wherein the component includes a turbine component. 
     
     
         9 . The method of  claim 8 , wherein the component is selected from the group consisting of: a turbine bucket, a turbine blade, or a turbine rotor. 
     
     
         10 . The method of  claim 1 , wherein a material of the surface is chemically homogeneous with a material of the remainder of the component. 
     
     
         11 . A component treated to minimize stress corrosion cracking (SCC), having a structural metallic layer having a relatively high structural tensile strength; and a treated metallic layer composed of a material that is chemically homogeneous with the structural metallic layer, the treated metallic layer substantially forming at least a portion of an outer surface of the component and having a treated tensile strength that is lower than the structural layer tensile strength, the component formed by the process, comprising:
 heating a surface of the component to a temperature at which at least one of tempering or annealing of the exterior surface of the component occurs; and   cooling the surface of the component in a controlled manner so as to maintain a resultant surface tensile strength that minimizes SCC.   
     
     
         12 . The component of  claim 11 , wherein the heating includes induction heating. 
     
     
         13 . The component of  claim 11 , wherein the temperature is greater than 540 degrees Celsius. 
     
     
         14 . The component of  claim 11 , wherein the heating and cooling produce a full anneal of the surface. 
     
     
         15 . The component of  claim 11 , wherein the cooling includes:
 maintaining a heating apparatus in an operational position with respect to the component; and   adjusting the heating in a manner that causes the temperature in the surface to decrease along a desired thermal profile.   
     
     
         16 . The component of  claim 11 , wherein the component includes a generator component. 
     
     
         17 . The method of  claim 16 , wherein the component is selected from the group consisting of: a generator rotor or a generator retaining ring. 
     
     
         18 . The component of  claim 11 , wherein the component includes a turbine component. 
     
     
         19 . The component of  claim 18 , wherein the component is selected from the group consisting of: a turbine bucket, a turbine blade or a turbine rotor.