Low-cost Fe—Ni—Cr alloys for high temperature valve applications
An Fe—Ni—Cr alloy is composed essentially of, in terms of weight percent: 1 to 3.5 Al, up to 2 Co, 15 to 19.5 Cr, up to 2 Cu, 23 to 40 Fe, up to 0.3 Hf, up to 4 Mn, 0.15 to 2 Mo, up to 0.15 Si, up to 1.05 Ta, 2.8 to 4.3 Ti, up to 0.5 W, up to 0.06 Zr, 0.02 to 0.15 C, 0.0001 to 0.007 N, balance Ni, wherein, in terms of atomic percent: 6.5≦Al+Ti+Zr+Hf+Ta≦10, 0.33≦Al÷(Al+Ti+Zr+Hf+Ta)≦0.065, 4≦(Fe+Cr)÷(Al+Ti+Zr+Hf+Ta)≦10, the alloy being essentially free of Nb and V.
1. An Fe-Ni-Cr Alloy, consisting essentiality of, in terms of weight percent:
Al 1 to 3.5
Co up to 2
Cr 15 to 19.5
Cu up to 2
Fe 24.09 to 34.89
Hf up to 0.3
Mn up to 4
Mo 0.15 to 2
Si up to 0.15
Ta up to 1.05
Ti 2.8 to 4.3
W up to 0.5
Zr up to 0.06
C 0.02 to 0.15
N 0.0001 to 0.007
balance Ni,
wherein, in terms of atomic percent:
5.9≦Al+Ti+Zr+Hf+Ta≦10.5,
0.3≦Al÷(Al+Ti+Zr+Hf+Ta)≦0.65, and
0.17≦Cr÷(Fe+Ni+Cr+Mn)≦0.23,
said alloy being free of Nb and essentially free of V; and,
said alloy comprising γ and γ′ phases, wherein the lattice misfit at 870° C. of the γ and γ′ phases is between −0.135% and +0.064%.
2. An alloy in accordance with claim 1 wherein the range of Al is 1.18 to 3.15 weight percent.
3. An alloy in accordance with claim 1 wherein the range of Co is up to 1.97 weight percent.
4. An alloy in accordance with claim 1 wherein the range of Cr is 15.25 to 19.2 weight percent.
5. An alloy in accordance with claim 1 wherein the range of Cu is up to 1.99 weight percent.
6. An alloy in accordance with claim 1 wherein the range of Hf is up to 0.25 weight percent.
7. An alloy in accordance with claim 1 wherein the range of Mn is up to 3.88 weight percent.
8. An alloy in accordance with claim 1 wherein the range of Mo is 0.2 to 1.62 weight percent.
9. An alloy in accordance with claim 1 wherein the range of Si is up to 0.13 weight percent.
10. An alloy in accordance with claim 1 wherein the range of Ta is up to 1.02 weight percent.
11. An alloy in accordance with claim 1 wherein the range of Ti is 2.94 to 4.19 weight percent.
12. An alloy in accordance with claim 1 wherein the range of W is up to 0.4 weight percent.
13. An alloy in accordance with claim 1 wherein the range of Zr is up to 0.05 weight percent.
14. An alloy in accordance with claim 1 wherein the range of C is 0.025 to 0.1 weight percent.
15. An alloy in accordance with claim 1 wherein, in terms of atomic percent, 5.9≦Al+Ti+Zr+Hf+Ta≦10.5.
16. An alloy in accordance with claim 15 wherein, in terms of atomic percent, 6≦Al+Ti+Zr+Hf+Ta≦9.
17. An alloy in accordance with claim 16 wherein, in terms of atomic percent, 7.5≦Al+Ti+Zr+Hf+Ta≦8.5.
18. An alloy in accordance with claim 1 wherein, in terms of atomic percent, 0.3≦Al÷(Al+Ti+Zr+Hf+Ta)≦0.65.
19. An alloy oy in accordance with claim 18 wherein, in terms of atomic percent, 0.35≦(Al÷(Al+Ti+Zr+Hf+Ta)≦0.6.
20. An alloy in accordance with claim 19 wherein, in terms of atomic percent, 0.4≦(Al÷(Al+Ti+Zr+Hf+Ta)≦0.55.
21. An alloy in accordance with claim 20 wherein, in terms of atomic percent, 0.44≦Al÷(Al+Ti+Zr+Hf+Ta)≦0.46.
22. An alloy in accordance with claim 1 wherein, in terms of atomic percent, 0.17≦Cr÷(Ni+Fe+Cr+Mn)≦0.23.
23. An alloy in accordance with claim 22 wherein, in terms of atomic percent, 0.18≦Cr÷(Ni+Fe+Cr+Mn)≦0.22.
24. An alloy in accordance with claim 23 wherein, in terms of atomic percent, 0.185≦Cr÷(Ni+Fe+Cr+Mn)≦0.215.
25. An alloy in accordance with claim 24 wherein, in terms of atomic percent, 0.200≦Cr÷(Ni+Fe+Cr+Mn)≦0.213.