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

• US 20050126662A1
• Filed: 12/10/2003
• Published: 06/16/2005
• Est. Priority Date: 12/10/2003
• Status: Active Grant

• Current Assignee: ATI Properties Incorporated (Allegheny Technologies Incorporated)
• Original Assignee: ATI Properties Incorporated (Allegheny Technologies Incorporated)
• Inventors: Cao, Wei-Di
• Granted Patent: US 7,901,519 B2
• Time in Patent Office: Days
• US Class Current: 148/326
• CPC Class Codes: C22C 38/06 containing aluminium
• CPC Class Codes: C22C 38/42 with copper
• CPC Class Codes: C22C 38/44 with molybdenum or tungsten
• CPC Class Codes: C22C 38/50 with titanium or zirconium

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

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;

up to 2.0% tungsten; and

up to 0.001% boron.

2. The stainless steel of claim 1, wherein iron is substantially the remainder of the total content.

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

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

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

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

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

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

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

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

11. The stainless steel of claim 1, wherein the amount of nickel ranges from 9.0% to 10.0% by weight.

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

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

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

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

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

17. The stainless steel of claim 1 having a yield strength of at least 230 ksi, K_1C of at least 70 ksi.in^1/2 and K_1SCC of at least 50 ksi.in^1/2.

18. The stainless steel of claim 1, wherein:

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

220

19. 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

20. 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;

up to 2.0% tungsten;

up to 0.001% boron;

iron; and

incidental impurities.

21. The stainless steel of claim 20, wherein the amount of chromium ranges from 11.0% to 12.0% by weight.

22. The stainless steel of claim 20, wherein the amount of molybdenum ranges from 1.0% to 2.0% by weight.

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

24. The stainless steel of claim 20, wherein the amount of titanium ranges from 0.3% to 0.5% by weight.

25. The stainless steel of claim 20, wherein the amount of aluminum ranges from 1.0% to 1.3% by weight.

26. The stainless steel of claim 20, wherein the amount of aluminum ranges from 0.9% to 1.2% by weight.

27. The stainless steel of claim 20, wherein the amount of copper ranges from 1.5% to 2.5% by weight.

28. The stainless steel of claim 20, wherein the amount of copper ranges from 0.5% to 1.5% by weight.

29. The stainless steel of claim 20, wherein the amount of nickel ranges from 9.0% to 10.0% by weight.

30. The stainless steel of claim 20, wherein the amount of nickel ranges from 9.5% to 10.5% by weight.

31. The stainless steel of claim 20, wherein the amount of carbon ranges from 0.006% to 0.016% by weight.

32. The stainless steel of claim 20, wherein the amount of carbon ranges from 0.008% to 0.012% by weight.

33. The stainless steel of claim 20, wherein the amount of carbon ranges from 0.01% to 0.016% by weight.

34. The stainless steel of claim 20, wherein the amount of tungsten ranges from 0.5% to 1.5% by weight.

35. The stainless steel of claim 20 having a yield strength of at least 230 ksi, K_1C of at least 70 ksi.in^1/2 and K_1SCC of at least 50 ksi.in^1/2.

36. The stainless steel of claim 20, wherein:

194.4+20.9(% Al)+22.7(% Ti)+6.8(% Cu)≧

220

37. The stainless steel of claim 36, 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

38. 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.

39. The stainless steel of claim 38 having a yield strength of at least 230 ksi, K_1C of at least 70 ksi.in^1/2 and K_1SCC of at least 50 ksi.in^1/2.

40. The stainless steel of claim 38, 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;

0.15% 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;

up to 0.001% boron;

iron; and

incidental impurities.

43. The stainless steel of claim 42 having a yield strength of at least 230 ksi, K_1C of at least 70 ksi.in^1/2 and K_1SCC of at least 50 ksi.in^1/2.

44. The stainless steel of claim 42, wherein:

194.4+20.9(% Al)+22.7(% Ti)+6.8(% Cu)≧

220

45. The stainless steel of claim 44, 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

46. 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.

47. The stainless steel of claim 46 having a yield strength of at least 230 ksi, K_1C of at least 70 ksi.in^1/2 and K_1SCC of at least 50 ksi.in^1/2.

48. The stainless steel of claim 46, wherein:

194.4+20.9(% Al)+22.7(% Ti)+6.8(% Cu)≧

220

49. The stainless steel of claim 48, 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

50. 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;

up to 0.001% boron;

iron; and

incidental impurities.

51. The stainless steel of claim 50 having a yield strength of at least 230 ksi, K_1C of at least 70 ksi.in^1/2 and K_1SCC of at least 50 ksi.in^1/2.

52. The stainless steel of claim 50, wherein:

194.4+20.9(% Al)+22.7(% Ti)+6.8(% Cu)≧

220

53. The stainless steel of claim 52, 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

54. 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;

up to 2.0% tungsten; and

up to 0.001% boron.

55. The article of manufacture of claim 54, selected from the group consisting of flap tracks, actuators, engine mounts, landing gear hardware, handgun barrels, and vehicle parts.

56. 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;

up to 2.0% tungsten;

up to 0.001% boron;

iron; and

incidental impurities.

57. 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.

58. 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.

59. 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;

up to 2.0% tungsten; and

up to 0.001% boron; and

processing the heat to form the precipitation hardenable martensitic stainless steel.

60. The method of claim 59, wherein iron is included as substantially the remainder of the total content.

61. The method of claim 59, wherein the amount of chromium ranges from 11.0% to 12.0% by weight.

62. The method of claim 59, wherein the amount of molybdenum ranges from 1.0% to 2.0% by weight.

63. The method of claim 59, wherein the amount of titanium ranges from 0.15% to 0.3% by weight.

64. The method of claim 59, wherein the amount of titanium ranges from 0.3% to 0.5% by weight.

65. The method of claim 59, wherein the amount of aluminum ranges from 1.0% to 1.3% by weight.

66. The method of claim 59, wherein the amount of aluminum ranges from 0.9% to 1.2% by weight.

67. The method of claim 59, wherein the amount of copper ranges from 1.5% to 2.5% by weight.

68. The method of claim 59, wherein the amount of copper ranges from 0.5% to 1.5% by weight.

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

70. The method of claim 59, wherein the amount of nickel ranges from 9.5% to 10.5% by weight.

71. The method of claim 59, wherein the amount of carbon ranges from 0.006% to 0.016% by weight.

72. The method of claim 59, wherein the amount of carbon ranges from 0.008% to 0.012% by weight.

73. The method of claim 59, wherein the amount of carbon ranges from 0.01% to 0.016% by weight.

74. The method of claim 59, wherein the amount of tungsten ranges from 0.5% to 1.5% by weight.