Nickel-chromium-iron alloys with improved resistance to stress corrosion cracking in nuclear environments

Abstract

A Ni—Cr—Fe alloy with improved resistance to stress corrosion cracking in nuclear environments, the alloy comprising 23-28 wt % Cr, 25-35 wt % Ni, <0.03 wt % C, <0.70 wt % Si, <1.0 wt % Mn, <0.015 wt % S, >0.35 wt % Ti, 0.15-0.45 wt % Al, <0.75 wt % Cu, and balance Fe and incidental impurities. The alloy may be used in steam generator tubing of a nuclear reactor. A method of producing an article includes: providing the alloy as disclosed herein; forming the alloy into the article by cold working the alloy to 20%; and heat treating the article.

1 . A Ni—Cr—Fe alloy with improved resistance to stress corrosion cracking in nuclear environments, wherein the alloy has between about 23 and 28 wt % Cr. 
     
     
         2 . The alloy of  claim 1 , wherein the alloy has between about 24 to 27 wt % Cr. 
     
     
         3 . The alloy of  claim 1 , wherein the alloy has about 25 wt % Cr. 
     
     
         4 . The alloy of  claim 1 , wherein the alloy has between about 25 and 35 wt % Ni. 
     
     
         5 . The alloy of  claim 1 , wherein the alloy has between about 32 and 35 wt % Ni. 
     
     
         6 . The alloy of  claim 1 , wherein the alloy has about 32 wt % Ni and about 25 wt % Cr. 
     
     
         7 . The alloy of  claim 1 , wherein the alloy has about 25 wt % Ni and about 25 wt % Cr. 
     
     
         8 . The alloy of  claim 1 , wherein the alloy has about 35 wt % Ni and about 25 wt % Cr. 
     
     
         9 . The alloy of  claim 1 , wherein the alloy has about 32 wt % Ni and about 27 wt % Cr. 
     
     
         10 . The alloy of  claim 1 , wherein the alloy has:
 <0.03 wt % C;   <0.70 wt % Si;   <1.0 wt % Mn;   <0.015 wt % S;   >0.35 wt % Ti;   between 0.15 and 0.45 wt % Al;   <0.75 wt % Cu;   <0.03 wt % N;   >12 Ti/C; and   balance substantially Fe and incidental impurities.   
     
     
         11 . Use of the alloy of  claim 1  in a nuclear reactor. 
     
     
         12 . Use of the alloy of  claim 1  in steam generator tubing of a nuclear reactor. 
     
     
         13 . A method of producing an article, the method comprising:
 providing a Ni—Cr—Fe alloy with improved resistance to stress corrosion cracking in nuclear environments, wherein the alloy has between about 23 and 27 wt % Cr and between about 25 and 35 wt %;   forming the alloy into the article; and   heat treating the article.   
     
     
         14 . The method of  claim 13 , wherein the step of heat treating consists of solution annealing the article at at least about 1000° C. for at least about 3 minutes. 
     
     
         15 . The method of  claim 13 , wherein the step of heat treating consists of solution annealing the article at between about 1050° C. to 1100° C. for at least about 3 minutes. 
     
     
         16 . The method of  claim 13 , wherein the step of heat treating consists of solution annealing the article at about 1075° C. for about 1 hour. 
     
     
         17 . The method of  claim 13 , further comprising, after the step of heat treating, rapidly cooling the article. 
     
     
         18 . The method of  claim 13 , wherein the step of forming comprises cold working the article to about 20%. 
     
     
         19 . The method of  claim 13 , wherein, after the step of heat treating, the article has an average grain size of about 100 μm. 
     
     
         20 . (canceled) 
     
     
         21 . A Ni—Cr—Fe alloy with improved resistance to stress corrosion cracking in nuclear environments, wherein the alloy has:
 between about 23 and 27 wt % Cr; 
 between about 25 and 35 wt % Ni 
 <0.03 wt % C; 
 <0.70 wt % Si; 
 <1.0 wt % Mn; 
 <0.015 wt % S; 
 >0.35 wt % Ti; 
 between 0.15 and 0.45 wt % Al; 
 <0.75 wt % Cu; 
 <0.03 wt % N; 
 >12 Ti/C; and 
 balance substantially Fe and incidental impurities.