Nickel-base precipitation hardenable alloys with improved hydrogen embrittlement resistance

Abstract

Nickel-base precipitation hardenable alloys with enhanced hydrogen embrittlement resistance and desired yield strength have critical ranges of titanium and iron, among other elements. One of the nickel-base precipitation hardenable alloys has a composition, in wt.%, of Cr from about 18.0% to about 23.0%, Fe from about 7.0% to about 12.0%, Mo from about 6.5% to about 9.5%, Nb from about 3.2% to about 5.2%, Ti from about 0.3% to about 1.3%, Al up to about 0.4%, with a balance of Ni and incidental impurities. This alloy has a yield strength (0.2% offset) greater than or equal to 120 ksi (827 MPa), a plastic strain ratio greater than or equal to 0.35, and a plastic strain to failure greater than or equal to 9.0%.

What is claimed is: 
     
         1 . A nickel-based precipitation hardenable alloy comprising:
 a composition, in weight percent, comprising: 
 chromium from about 18.0% to about 23.0%; 
 iron from about 7.0% to about 12.0%; 
 molybdenum from about 6.5% to about 9.5%; 
 niobium from about 3.2% to about 5.2%; 
 titanium from about 0.3% to about 1.3%; 
 aluminum up to about 0.4%; and 
 balance nickel and incidental impurities; 
 
wherein the nickel-based precipitation hardenable alloy has: 
 a yield strength (0.2% offset) greater than or equal to about 120 ksi (827 MPa); 
 a plastic strain ratio greater than or equal to 0.35; and 
 a plastic strain to failure greater than or equal to 9.0%. 
 
     
     
         2 . The nickel-based precipitation hardenable alloy according to  claim 1 , wherein the titanium is between about 0.8% to about 1.1% and the iron is between about 9.0% to about 12.0%. 
     
     
         3 . The nickel-based precipitation hardenable alloy according to  claim 1 , wherein the titanium is between about 0.8% to about 1.0% and the iron is between about 10.0% to about 12.0%. 
     
     
         4 . The nickel-based precipitation hardenable alloy according to  claim 1 , wherein the titanium is between about 0.4% to about 0.8% and the iron is between about 10.0% to about 12.0%. 
     
     
         5 . The nickel-based precipitation hardenable alloy according to  claim 1 , wherein the yield strength (0.2% offset) is between about 120 ksi (827 MPa) and 150 ksi (1034 MPa). 
     
     
         6 . The nickel-based precipitation hardenable alloy according to  claim 1 , wherein the plastic strain ratio is greater than or equal to 0.40, and the plastic strain to failure is greater than or equal to 10.0%. 
     
     
         7 . The nickel-based precipitation hardenable alloy according to  claim 1 , wherein the plastic strain ratio is greater than or equal to 0.50, and the plastic strain to failure is greater than or equal to 12.0%. 
     
     
         8 . A nickel-based precipitation hardenable alloy comprising:
 a composition, in weight percent, comprising: 
 chromium from about 18.0% to about 23.0%; 
 iron from about 9.0% to about 16.0%; 
 molybdenum from about 4.5% to about 7.5%; 
 niobium from about 3.2% to about 5.2%; 
 titanium from about 0.4% to about 1.3%; 
 aluminum up to about 0.4%; and 
 balance nickel and incidental impurities; 
 
wherein the nickel-based precipitation hardenable alloy has: 
 a yield strength (0.2% offset) greater than or equal to about 120 ksi (827 MPa); 
 a plastic strain ratio greater than or equal to 0.30; and 
 a plastic strain to failure greater than or equal to 8.5%. 
 
     
     
         9 . The nickel-based precipitation hardenable alloy according to  claim 8 , wherein the titanium is between about 0.8% to about 1.1% and the iron is between about 11.0% to about 16.0%. 
     
     
         10 . The nickel-based precipitation hardenable alloy according to  claim 8 , wherein the titanium is between about 0.8% to about 1.0% and the iron is between about 12.0% to about 16.0%. 
     
     
         11 . The nickel-based precipitation hardenable alloy according to  claim 8 , wherein the titanium is between about 0.5% to about 0.8% and the iron is between about 12.0% to about 16.0%. 
     
     
         12 . The nickel-based precipitation hardenable alloy according to  claim 8 , wherein the yield strength (0.2% offset) is between about 120 ksi (827 MPa) and 150 ksi (1034 MPa). 
     
     
         13 . The nickel-based precipitation hardenable alloy according to  claim 8 , wherein the plastic strain ratio is greater than or equal to 0.35, and the plastic strain to failure is greater than or equal to 9.0%. 
     
     
         14 . The nickel-based precipitation hardenable alloy according to  claim 8 , wherein the plastic strain ratio is greater than or equal to 0.45, and the plastic strain to failure is greater than or equal to 10.0%. 
     
     
         15 . A nickel-based precipitation hardenable alloy comprising:
 a composition, in weight percent, comprising: 
 chromium from about 18.0% to about 23.0%; 
 iron from about 15.0% to about 21.0%; 
 molybdenum from about 3.0% to about 4.5%; 
 niobium from about 3.2% to about 5.2%; 
 titanium from about 0.5% to about 1.3%; 
 aluminum up to about 0.4%; 
 copper from about 0.5% to about 3.0%; and 
 balance nickel and incidental impurities; 
 
wherein the nickel-based precipitation hardenable alloy has: 
 a yield strength (0.2% offset) greater than or equal to about 140 ksi (965 MPa); 
 a plastic strain ratio greater than or equal to 0.30; and 
 a plastic strain to failure greater than or equal to 8.0%. 
 
     
     
         16 . The nickel-based precipitation hardenable alloy according to  claim 15 , wherein the titanium between about 0.8% to about 1.1% and the iron is between about 16.0% to about 21.0%. 
     
     
         17 . The nickel-based precipitation hardenable alloy according to  claim 15 , wherein the titanium between about 0.8% to about 1.0% and the iron is between about 17.0% to 20.0%. 
     
     
         18 . The nickel-based precipitation hardenable alloy according to  claim 15 , wherein the titanium between about 0.5% to about 0.8% and the iron is between about 18% to about 21.0%. 
     
     
         19 . The nickel-based precipitation hardenable alloy according to  claim 15 , wherein the yield strength (0.2% offset) is between about 140 ksi (965 MPa) and 170 ksi (1172 MPa). 
     
     
         20 . The nickel-based precipitation hardenable alloy according to  claim 15 , wherein the plastic strain ratio is greater than or equal to 0.35, and the plastic strain to failure is greater than or equal to 9.0%. 
     
     
         21 . The nickel-based precipitation hardenable alloy according to  claim 15 , wherein the plastic strain ratio is greater than or equal to 0.45, and the plastic strain to failure is greater than or equal to 10.0%.