Intermediate strength alloys for high temperature service in liquid-salt cooled energy systems

• US 9,683,279 B2
• Filed: 05/15/2014
• Issued: 06/20/2017
• Est. Priority Date: 05/15/2014
• Status: Active Grant

• Current Assignee: UT-Battelle LLC
• Original Assignee: UT-Battelle LLC
• Inventors: Wilson, Dane Francis, Holcomb, David Eugene, Muralidharan, Govindarajan
• Primary Examiner(s): Roe, Jessee
• Application Number:
  US14/277,992
• Publication Number:
  US 20150329942A1
• Time in Patent Office: 1,132 Days
• CPC Class Codes: C22C 19/05 with chromium
• CPC Class Codes: C22C 19/057 with the maximum Cr content being less 10%

Abstract

An alloy is composed essentially of, in terms of weight percent: 6 to 8.5 Cr, 5.5 to 13.5 Mo, 0.4 to 7.5 W, 1 to 2 Ti, 0.7 to 0.85 Mn, 0.05 to 0.3 Al, 0.08 to 0.5 C, 0 to 1 Nb, with the balance Ni, the alloy being characterized by, at 850° C., a yield strength of at least 25 Ksi, a tensile strength of at least 30 Ksi, a creep rupture life at 12 Ksi of at least 45 hours, and a corrosion rate, expressed in weight loss [g/(cm² sec)]10⁻¹¹ during a 1000 hour immersion in liquid FLiNaK at 850° C., in the range of 6 to 39.

Claims

1. An alloy consisting essentially of, in terms of weight percent:

Cr 6 to 8.5

Mo 5.5 to 13.5

W 0.4 to 7.5

Ti 1 to 2

Mn 0.7 to 0.85

Al 0.05 to 0.3

C 0.08 to 0.5

Nb 0 to 1

Ta 0 to 0.01

Ni balance

said alloy being characterized by, at 850°

C., a yield strength of at least 25 Ksi, a tensile strength of at least 30 Ksi, a creep rupture life at 12 Ksi of at least 45 hours, and a corrosion rate, expressed in weight loss [g/(cm² sec)]10<sup>−

11</sup> during a 1000 hour immersion in liquid FLiNaK at 850°

C., in the range of 6 to 39, wherein said alloy is devoid of γ

′

precipitates, and is further characterized by a corrosion susceptibility index of from 0.10 to 0.14, and wherein said alloy is essentially Fe free, Co free, and Hf free.

2. An alloy in accordance with claim 1 wherein said alloy is essentially Nb free.

3. An alloy in accordance with claim 1 wherein said alloy is essentially Ta free.

4. An alloy in accordance with claim 1 wherein the range of Cr is 6.6 to 7.22 weight percent.

5. An alloy in accordance with claim 1 wherein the range of Mo is 5.76 to 12.79 weight percent.

6. An alloy in accordance with claim 1 wherein the range of W is 0.44 to 6.32 weight percent.

7. An alloy in accordance with claim 1 wherein the range of Ti is 1.15 to 1.22 weight percent.

8. An alloy in accordance with claim 1 wherein the range of Mn is 0.75 to 0.77 weight percent.

9. An alloy in accordance with claim 1 wherein the range of Al is 0.09 to 0.2 weight percent.

10. An alloy in accordance with claim 1 wherein the range of C is 0.2 to 0.47 weight percent.

11. An alloy in accordance with claim 1 wherein said alloy is further characterized by 5.4 to 16.84 wt. % total carbides.

12. An alloy in accordance with claim 11 wherein said alloy is further characterized by 1.92 to 16.14 wt. % M₆C carbides.

13. An alloy in accordance with claim 11 wherein said alloy is further characterized by up to 3.48 wt. % M₂₃C₆ carbides.

14. An alloy in accordance with claim 1 wherein said yield strength is at least 30 Ksi.

15. An alloy in accordance with claim 1 wherein said tensile strength is at least 34 Ksi.

16. An alloy in accordance with claim 1 wherein said creep rupture life is at least 47 hours.

17. An alloy in accordance with claim 1 wherein said alloy is further characterized by a Mo equivalent of no less than 4, wherein:

18. An alloy in accordance with claim 1 wherein the range of C is from 0.24 to 0.5 weight percent.