Intermediate strength alloys for high temperature service in liquid-salt cooled energy systems
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/(cm 2 sec)]10 −11 during a 1000 hour immersion in liquid FLiNaK at 850° C., in the range of 6 to 39.
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/(cm 2 sec)]10 −11 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. % M 6 C carbides.
13. An alloy in accordance with claim 11 wherein said alloy is further characterized by up to 3.48 wt. % M 23 C 6 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:
Mo
Equivalent
=
%
Mo
+
1.15
×
183.84
(
Atomic
Weight
of
W
)
95.95
(
Atomic
Weight
of
Mo
)
×
%
W
,
wherein % is atomic percent.
18. An alloy in accordance with claim 1 wherein the range of C is from 0.24 to 0.5 weight percent.