IP Library › Granted Patent US 7,901,519

Granted Patent B2

US 7,901,519 · App. 10/732,571 · Granted Mar 8, 2011

High strength martensitic stainless steel alloys, methods of forming the same, and articles formed therefrom

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Quick Facts

Patent No.: US 7,901,519
App. No.: 10/732,571
Granted: Mar 8, 2011
Kind: B2

External Links

USPTO Patent Center↗ Full Patent PDF↗

Abstract

A precipitation hardenable martensitic stainless steel that includes, in percent by weight, 11.0 to 12.5 percent chromium, 1.0 to 2.5 percent molybdenum, 0.15 to 0.5 percent titanium, 0.7 to 1.5 percent aluminum, 0.5 to 2.5 percent copper, 9.0 to 11.0 percent nickel, up to 0.02 percent carbon, up to 2.0 percent tungsten, and up to 0.001 percent boron. Articles formed from the stainless steel and methods of forming the same are also disclosed.

Claims (186)

1. A precipitation-hardenable martensitic stainless steel comprising, in percent by weight:

11.0% to 12.5% chromium;

1.0% to 2.5% molybdenum;

0.15% to 0.5% titanium;

0.7% to 1.5% aluminum;

0.5% to 2.5% copper;

9.0% to 11.0% nickel;

up to 0.02% carbon;

0. 5% to 1.5% tungsten; and

up to 0.001% boron;

wherein iron and incidental impurities are substantially the remainder of the total content, and wherein the stainless steel has a yield strength of at least 230 ksi, K IC of at least 70 ksi·in 1/2 , and K ISCC of at least 50 ksi·in 1/2 .

2. The stainless steel of claim 1 , wherein the amount of chromium ranges from 11.0% to 12.0% by weight.

3. The stainless steel of claim 1 , wherein the amount of molybdenum ranges from 1.0% to 2.0% by weight.

4. The stainless steel of claim 1 , wherein the amount of titanium ranges from 0.15% to 0.3% by weight.

5. The stainless steel of claim 1 , wherein the amount of titanium ranges from 0.3% to 0.5% by weight.

6. The stainless steel of claim 1 , wherein the amount of aluminum ranges from 1.0% to 1.3% by weight.

7. The stainless steel of claim 1 , wherein the amount of aluminum ranges from 0.9% to 1.2% by weight.

8. The stainless steel of claim 1 , wherein the amount of copper ranges from 1.5% to 2.5% by weight.

9. The stainless steel of claim 1 , wherein the amount of copper ranges from 0.5% to 1.5% by weight.

10. The stainless steel of claim 1 , wherein the amount of nickel ranges from 9.5% to 10% by weight.

11. The stainless steel of claim 1 , wherein the amount of nickel ranges from 9.5% to 10.5% by weight.

12. The stainless steel of claim 1 , wherein the amount of carbon ranges from 0.006% to 0.016% by weight.

13. The stainless steel of claim 1 , wherein the amount of carbon ranges from 0.008% to 0.012% by weight.

14. The stainless steel of claim 1 , wherein the amount of carbon ranges from 0.01% to 0.016% by weight.

15. The stainless steel of claim 1 , wherein:

194.4+20.9 (% Al)+22.7(% Ti)+6.8(% Cu)>220.

16. The stainless steel of claim 1 , wherein:

1200(% C−0.006)+23(% Cr−12)+40(% Ni−9)+16(%(Mo+1/2W)−1.5) +3.75(% Al)+34(% Ti)+20(% Cu)≦100.

17. A precipitation-hardenable martensitic stainless steel consisting essentially of, in percent by weight:

11.0% to 12.5% chromium;

1% to 2.5% molybdenum;

0.15% to 0.5% titanium;

0.7% to 1.5% aluminum;

0.5% to 2.5% copper;

9.0% to 11.0% nickel;

up to 0.02% carbon;

0.5% to 1.5% tungsten; and

up to 0.001% boron;

18. The stainless steel of claim 17 , wherein the amount of chromium ranges from 11.0% to 12.0% by weight.

19. The stainless steel of claim 17 , wherein the amount of molybdenum ranges from 1.0% to 2.0% by weight.

20. The stainless steel of claim 17 , wherein the amount of titanium ranges from 0.15% to 0.3% by weight.

21. The stainless steel of claim 17 , wherein the amount of titanium ranges from 0.3% to 0.5% by weight.

22. The stainless steel of claim 17 , wherein the amount of aluminum ranges from 1.0% to 1.3% by weight.

23. The stainless steel of claim 17 , wherein the amount of aluminum ranges from 0.9% to 1.2% by weight.

24. The stainless steel of claim 17 , wherein the amount of copper ranges from 1.5% to 2.5% by weight.

25. The stainless steel of claim 17 , wherein the amount of copper ranges from 0.5% to 1.5% by weight.

26. The stainless steel of claim 17 , wherein the amount of nickel ranges from 9.5% to 10% by weight.

27. The stainless steel of claim 17 , wherein the amount of nickel ranges from 9.5% to 10.5% by weight.

28. The stainless steel of claim 17 , wherein the amount of carbon ranges from 0.006% to 0.016% by weight.

29. The stainless steel of claim 17 , wherein the amount of carbon ranges from 0.008% to 0.012% by weight.

30. The stainless steel of claim 17 , wherein the amount of carbon ranges from 0.01% to 0.016% by weight.

31. The stainless steel of claim 17 , wherein:

194.4+20.9 (% Al)+22.7(% Ti)+6.8(% Cu)>220.

32. The stainless steel of claim 31 , wherein:

1200(% C−0.006)+23(% Cr−12)+40(% Ni−9)+16(%(Mo+1/2W)−1.5) +3.75(% Al)+34(% Ti)+20(% Cu)≦100.

33. A precipitation-hardenable martensitic stainless steel comprising, in percent by weight:

11.0% to 12.0% chromium;

1.0% to 2.0% molybdenum;

0.15% to 0.3% titanium;

1.0% to 1.3% aluminum;

1.5% to 2.5% copper;

9.0% to 10.0% nickel;

0.008% to 0.012% carbon;

0.5% to 1.5% tungsten; and

up to 0.001% boron;

34. The stainless steel of claim 33 , wherein:

194.4+20.9 (% Al)+22.7(% Ti)+6.8(% Cu)>220.

35. The stainless steel of claim 34 , wherein:

1200(% C−0.006)+23(% Cr−12)+40(% Ni−9)+16(%(Mo+1/2W)−1.5) +3.75(% Al)+34(% Ti)+20(% Cu)≦100.

36. A precipitation-hardenable martensitic stainless steel consisting essentially of, in percent by weight:

11.0% to 12.0% chromium;

1.0% to 2.0% molybdenum;

0.15% to 0.3% titanium;

1.0% to 1.3% aluminum;

1.5% to 2.5% copper;

9.0% to 10.0% nickel;

0.008% to 0.012% carbon;

0.5% to 1.5% tungsten; and

up to 0.001% boron;

37. The stainless steel of claim 36 , wherein:

194.4+20.9 (% Al)+22.7(% Ti)+6.8(% Cu)>220.

38. The stainless steel of claim 37 , wherein:

1200(% C−0.006)+23(% Cr−12)+40(% Ni−9)+16(%(Mo+1/2W)−1.5) +3.75(% Al)+34(% Ti)+20(% Cu)≦100.

39. A precipitation-hardenable martensitic stainless steel stainless steel comprising, in percent by weight:

11.0% to 12.0% chromium;

1.0% to 2.0% molybdenum;

0.3% to 0.5% titanium;

0.9% to 1.2% aluminum;

0.5% to 1.5% copper;

9.5% to 10.5% nickel;

0.01% to 0.016% carbon;

0.5% to 1.5% tungsten; and

up to 0.001% boron;

40. The stainless steel of claim 39 , wherein:

194.4+20.9 (% Al)+22.7(% Ti)+6.8(% Cu)>220.

41. The stainless steel of claim 40 , wherein:

1200(% C−0.006)+23(% Cr−12)+40(% Ni−9)+16(%(Mo+1/2W)−1.5) +3.75(% Al)+34(% Ti)+20(% Cu)≦100.

42. A precipitation-hardenable martensitic stainless steel consisting essentially of, in percent by weight:

11.0% to 12.0% chromium;

1.0% to 2.0% molybdenum;

0.3% to 0.5% titanium;

0.9% to 1.2% aluminum;

0.5% to 1.5% copper;

9.5% to 10.5% nickel;

0.01% to 0.016% carbon;

0.5% to 1.5% tungsten; and

up to 0.001% boron;

43. The stainless steel of claim 42 , wherein:

194.4+20.9 (% Al)+22.7(% Ti)+6.8(% Cu)>220.

44. The stainless steel of claim 43 , wherein:

1200(% C−0.006)+23(% Cr−12)+40(% Ni−9)+16(%(Mo+1/2W)−1.5) +3.75(% Al)+34(% Ti)+20(% Cu)≦100.

45. An article of manufacture comprising a precipitation-hardenable martensitic stainless steel comprising, in percent by weight:

11.0% to 12.5% chromium;

1.0% to 2.5% molybdenum;

0.15% to 0.5% titanium;

0.7% to 1.5% aluminum;

0.5% to 2.5% copper;

9.0% to 11.0% nickel;

up to 0.02% carbon;

0.5% to 1.5% tungsten; and

up to 0.001% boron;

46. The article of manufacture of claim 45 , selected from the group consisting of flap tracks, actuators, engine mounts, landing gear hardware, handgun barrels, and vehicle parts.

47. An article of manufacture comprising a precipitation-hardenable martensitic stainless steel consisting essentially of, in percent by weight:

11.0% to 12.5% chromium;

1.0% to 2.5% molybdenum;

0.15% to 0.5% titanium;

0.7% to 1.5% aluminum;

0.5% to 2.5% copper;

9.0% to 11.0% nickel;

up to 0.02% carbon;

0.5% to 1.5% tungsten; and

up to 0.001% boron;

48. An article of manufacture comprising a precipitation-hardenable martensitic stainless steel comprising, in percent by weight:

11.0% to 12.0% chromium;

1.0% to 2.0% molybdenum;

0.15% to 0.3% titanium;

1.0% to 1.3% aluminum;

1.5% to 2.5% copper;

9.0% to 10.0% nickel;

0.008% to 0.012% carbon;

0.5% to 1.5% tungsten; and

up to 0.001% boron;

49. An article of manufacture comprising a precipitation-hardenable martensitic stainless steel comprising, in percent by weight:

11.0% to 12.0% chromium;

1.0% to 2.0% molybdenum;

0.3% to 0.5% titanium;

0.9% to 1.2% aluminum;

0.5% to 1.5% copper;

9.5% to 10.5% nickel;

0.01% to 0.016% carbon;

0.5% to 1.5% tungsten; and

up to 0.001% boron;

50. A method of forming a precipitation-hardenable martensitic stainless steel, the method comprising preparing a heat including, in percent by weight:

11.0% to 12.5% chromium;

1.0% to 2.5% molybdenum;

0.15% to 0.5% titanium;

0.7% to 1.5% aluminum;

0.5% to 2.5% copper;

9.0% to 11.0% nickel;

up to 0.02% carbon;

0.5% to 1.5% tungsten;

up to 0.001% boron; and

balance of iron and incidental impurities; and

processing the heat to form the precipitation-hardenable martensitic stainless steel, the stainless steel having a yield strength of at least 230 ksi, K IC of at least 70 ksi·in 1/2 , and K ISCC of at least 50 ksi·in 1/2 .

51. The method of claim 50 , wherein the amount of chromium ranges from 11.0% to 12.0% by weight.

52. The method of claim 50 , wherein the amount of molybdenum ranges from 1.0% to 2.0% by weight.

53. The method of claim 50 , wherein the amount of titanium ranges from 0.15% to 0.3% by weight.

54. The method of claim 50 , wherein the amount of titanium ranges from 0.3% to 0.5% by weight.

55. The method of claim 50 , wherein the amount of aluminum ranges from 1.0% to 1.3% by weight.

56. The method of claim 50 , wherein the amount of aluminum ranges from 0.9% to 1.2% by weight.

57. The method of claim 50 , wherein the amount of copper ranges from 1.5% to 2.5% by weight.

58. The method of claim 50 , wherein the amount of copper ranges from 0.5% to 1.5% by weight.

59. The method of claim 50 , wherein the amount of nickel ranges from 9.0% to 10.0% by weight.

60. The method of claim 50 , wherein the amount of nickel ranges from 9.5% to 10.5% by weight.

61. The method of claim 50 , wherein the amount of carbon ranges from 0.006% to 0.016% by weight.

62. The method of claim 50 , wherein the amount of carbon ranges from 0.008% to 0.012% by weight.

63. The method of claim 50 , wherein the amount of carbon ranges from 0.01% to 0.016% by weight.