Superalloys having improved resistance to hydrogen embrittlement and methods of producing and using the same

Claim 2

A cold-worked and age strengthened nickel and/or cobalt, chromium, molybdenum superalloy having less than 1 At% phosphorus in its grain boundaries, a tensile strength ranging from 150 to about 250 ksi and a resistance to hydrogen embrittlement such that when a steel anode is galvanically coupled to a test specimen of said superalloy and said test specimen is exposed to an aqueous test solution saturated with hydrogen sulfide containing 5% NaCl and 0.5% acetic acid, by weight, at room temperature and at atmospheric pressure, the test specimen resists hydrogen embrittlement or cracking for more than 25 days when it is stressed to 100% of the transverse 0.2% offset yield strength.

Claim 3

The cold-worked and age strengthened superalloy of claim 1 wherein said superalloy contains 12 to 25 wt. % chromium, from 10 to about 20 wt. % molybdenum, up to 10 wt. % iron, up to about 50 wt. % cobalt and the balance essentially nickel.

Claim 4

The superalloy of claim 2 wherein the superalloy is further characterized as containing less than 0.003 wt. % phosphorus, less than 0.02 wt. % carbon and less than 0.08 wt. % silicon.

Claim 5

The superalloy of claim 1 wherein said superalloy has the following chamical composition in weight percent: ______________________________________ Phosphorus <0.002 Chromium 14-17 Molybdenum 14-16 Iron 0-7 Cobalt 0-2.5 Aluminum 0-0.25 Columbium 0-4 Titanium, Zirconium or Hafnium 0-0.75 Tungsten 0-4 Manganese 0-1 Vanadium or Tantalum 0-0.4 Carbon 0-0.01 Silicon 0-0.03 Nickel and Incidental Impurities Balance ______________________________________

Claim 6

A cold-worked and age strengthened nickel and/or cobalt, chormium, molybdenum superalloy characterized by having less than 1 At% phosphorus in its grain boundaries, a high tensile strength and an improved resistance to hydrogen embrittlement when subjected to an oxygen-free hydrogen sulfide saturated, aqueous solution containing 5% NaCl and 0.5% acetic acid, by weight, at room temperature and at atmospheric pressure, said superalloy comprising 12 to 25 wt. % chromium, from about 10 to about 20 wt. % molybdenum, up to 10 wt. % iron, up to about 50 wt. % cobalt and the balance essentially nickel, and wherein the phosphorus content in said superalloy is maintained and controlled at a level of less than 0.003 wt. %.

Claim 7

A cold-worked and age strengthened nickel and/or cobalt, chormium, molybdenum superalloy characterized by having less than 1 At% phosphorus in its grain boundaries, a high tensile strength and an improved resistance to hydrogen embrittlement when subjected to an oxygen-free hydrogen sulfide saturated, aqueous solution containing 5% NaCl and 0.5% acetic acid, by weight, at room temperature and at atmospheric pressure, said superalloy comprising 12 to 25 wt. % chromium, from about 10 to about 20 wt. % molybdenum, up to 10 wt. % iron, up to about 50 wt. % cobalt and the balance essentially nickel, and wherein the phosphorus content in said superalloy is maintained and controlled at a level of less than 0.003 wt. %.

Claim 8

A cold-worked and age strengthened superalloy in accordance with claim 5 having the following composition in weight percent: ______________________________________ Phosphorus <0.003 Chromium 12-15 Molybdenum 10-20 Iron 0-10 Cobalt 0-50 Aluminum 0-0.5 Columbium 0-4 Titanium, Zirconium or Hafnium 0-3 Tungsten 0-7 Manganese 0-1 Vanadium or Tantalum 0-0.75 Carbon 0-0.02 Silicon 0-0.08 Nickel and Incidental Impurities Balance ______________________________________

Claim 9

A cold-worked and age strengthened superalloy in accordance with claim 5 having the following composition in weight percent: ______________________________________ Phosphorus <0.002 Chromium 14-17 Molybdenum 14-16 Iron 0-7 Cobalt 0-2.5 Aluminum 0-0.5 Columbium 0-4 Titanium, Zirconium or Hafnium 0-0.75 Tungsten 0-4 Manganese 0-1 Vanadium or Tantalum 0-0.4 Carbon 0-0.01 Silicon 0-0.03 Nickel and Incidental Impurities Balance ______________________________________

Claim 10

A cold-worked and age strengthened superalloy in accordance with claim 5 having the following composition in weight percent: ______________________________________ Phosphorus <0.001 Chromium 14-16 Molybdenum 15-17 Iron 4-7 Cobalt 0-2.5 Aluminum 0-0.2 Titanium 0-0.5 Tungsten 3-4.5 Manganese 0-1 Vanadium 0-0.4 Carbon 0-0.01 Silicon 0-0.03 Nickel 52-56 Incidental Impurities Balance ______________________________________

Claim 11

The superalloy of claim 5 wherein the superalloy has been cold-worked within the range from about 15% to about 90% reduction in area.

Claim 12

The superalloy of claim 6 wherein the superalloy has been cold-worked within the range from about 25% to about 75% reduction in area.

Claim 13

The superalloy of claim 7 wherein the superalloy has been cold-worked within the range from about 35% to about 65% reduction in area.

Claim 14

The superalloy of claim 8 wherein the superalloy has been cold-worked within the range from about 35% to about 65% reduction in area.

Claim 15

The superalloy of claim 5 which is further characterized as having been strengthened by aging at a temperature ranging from about 800° F. to about 1200° F.

Claim 16

The superalloy of claim 5 in the form of a tubular conduit.

Claim 17

A process for producing a superalloy characterized as having a high tensile stength and an improved resistance to hydrogen embrittlement when subjected to an oxygen-free hydrogen sulfide saturated aqueous solution containing 5% NaCl and 0.5% acetic acid, by weight, at room temperature and at atmospheric pressure, which comprises treating an alloy of the following chemical composition in weight percent: ______________________________________ Phosphorus <0.003 Chromium 12-25 Molybdenum 10-20 Iron 0-10 Cobalt 0-50 Aluminum 0-0.5 Columbium 0-4 Titanium, Zirconium or Hafnium 0-3 Tungsten 0-7 Manganese 0-1 Vanadium or Tantalum 0-0.75 Carbon 0-0.02 Silicon 0-0.08 Nickel and Incidental Impurities Balance ______________________________________ by the steps: (a) cold-working said alloy within the range from about 15% to about 90% reduction in area, and (b) age strengthening the cold-worked alloy at a temperature ranging from about 300° F. to about 1100° F.

Claim 18

A process for producing a superalloy characterized as having a high tensile stength and an improved resistance to hydrogen embrittlement when subjected to an oxygen-free hydrogen sulfide saturated aqueous solution containing 5% NaCl and 0.5% acetic acid, by weight, at room temperature and at atmospheric pressure, which comprises treating an alloy of the following chemical composition in weight percent: ______________________________________ Phosphorus <0.003 Chromium 12-25 Molybdenum 10-20 Iron 0-10 Cobalt 0-50 Aluminum 0-0.5 Columbium 0-4 Titanium, Zirconium or Hafnium 0-3 Tungsten 0-7 Manganese 0-1 Vanadium or Tantalum 0-0.75 Carbon 0-0.02 Silicon 0-0.08 Nickel and Incidental Impurities Balance ______________________________________ by the steps: (a) cold-working said alloy within the range from about 15% to about 90% reduction in area, and (b) age strengthening the cold-worked alloy at a temperature ranging from about 300° F. to about 1100° F.

Claim 19

A process for recovering oil and/or gas from subterranean surfaces under conditions of high stress and hydrogen sulfide environments which comprises using a tubular conduit for transporting said oil and/or gas from subterranean surfaces, wherein said tubular conduit comprises a cold-worked and age strengthened nickel and/or cobalt, chromium, molybdenum superalloy having less than 1 At% phosphorus in its grain boundaries, a tensile strength ranging from 150 to about 250 ksi and a resistance to hydrogen embrittlement such that when a steel anode is galvanically coupled to a test C-ring of said superalloy and said C-ring is exposed to an aqueous test solution saturated with hydrogen sulfide containing 5% NaCl and 0.5% acetic acid, by weight, at room temperature and at atmospheric pressure, the test C-ring resists hydrogen embrittlement or cracking for more than 25 days when it is stressed to 100% of the transverse 0.2% offset yield strength.

Claim 20

A process for recovering oil and/or gas from subterranean surfaces under conditions of high stress and hydrogen sulfide environments which comprises using a tubular conduit for transporting said oil and/or gas from subterranean surfaces, wherein said tubular conduit comprises a cold-worked and age strengthened nickel and/or cobalt, chromium, molybdenum superalloy having less than 1 At% phosphorus in its grain boundaries, a tensile strength ranging from 150 to about 250 ksi and a resistance to hydrogen embrittlement such that when a steel anode is galvanically coupled to a test C-ring of said superalloy and said C-ring is exposed to an aqueous test solution saturated with hydrogen sulfide containing 5% NaCl and 0.5% acetic acid, by weight, at room temperature and at atmospheric pressure, the test C-ring resists hydrogen embrittlement or cracking for more than 25 days when it is stressed to 100% of the transverse 0.2% offset yield strength.

Claim 21

The process of claim 16 wherein said superalloy contains 12 to 25 wt. % chromium, from 10 to about 20 wt. % molybdenum, up to 10 wt. % iron, up to about 50 wt. % cobalt and the balance essentially nickel.

Claim 22

The process of claim 17 wherein the superalloy is further characterized as containing less than 0.003 wt. % phosphorus, less than 0.02 wt. % carbon and less than 0.08 wt. % silicon.

Claim 23

The process of claim 16 wherein said superalloy has the following chemical composition in weight percent: ______________________________________ Phosphorus <0.002 Chromium 14-17 Molybdenum 14-16 Iron 0-7 Cobalt 0-2.5 Aluminum 0-0.5 Columbium 0-4 Titanium, Zirconium or Hafnium 0-0.75 Tungsten 0-4 Manganese 0-1 Vanadium or Tantalum 0-0.4 Carbon 0-0.01 Silicon 0-0.03 Nickel and Incidental Impurities Balance ______________________________________