Low-cost, high-strength Fe—Ni—Cr alloys for high temperature exhaust valve applications
View Patent ↗An Fe—Ni—Cr alloy is composed essentially of, in terms of wt. %: 2.4 to 3.7 Al, up to 1.05 Co, 14.8 to 15.9 Cr, 25 to 36 Fe, up to 1.2 Hf, up to 4 Mn, up to 0.6 Mo, up to 2.2 Nb, up to 1.05 Ta, 1.9 to 3.6 Ti, up to 0.08 W, up to 0.03 Zr, 0.18 to 0.27 C, up to 0.0015 N, balance Ni, wherein, in terms of atomic percent: 8.5≦Al+Ti+Zr+Hf+Ta≦11.5, 0.53≦Al÷(Al+Ti+Zr+Hf+Ta)≦0.65, and 0.16≦Cr÷(Fe+Ni+Cr+Mn)≦0.21, the alloy being essentially free of Cu, Si, and V.
1. An Fe—Ni—Cr alloy consisting essentially of, in terms of wt. %:
Al 2.4 to 3.7
Co up to 1.05
Cr 14.8 to 15.9
Fe 25 to 36
Hf up to 1.2
Mn up to 4
Mo up to 0.6
Nb up to 2.2
Ta up to 1.05
Ti 1.9 to 3.6
W up to 0.08
Zr up to 0.03
C 0.18 to 0.27
N up to 0.0015
balance Ni,
wherein, in terms of atomic percent:
8.5≦Al+Ti+Zr+Hf+Ta≦11.5,
0.53≦Al÷(Al+Ti+Zr+Hf+Ta)≦0.65, and
0.16≦Cr÷(Fe+Ni+Cr+Mn)≦0.21,
said alloy being essentially free of Cu, Si, and V.
2. An Alloy in accordance with claim 1 wherein the range of Al is 2.5 to 3.56 weight percent.
3. An Alloy in accordance with claim 1 wherein the range of Co is up to 1.01 weight percent.
4. An Alloy in accordance with claim 1 wherein the range of Cr is 14.93 to 15.76 weight percent.
5. An Alloy in accordance with claim 1 wherein the range of Fe is 25.87 to 35 weight percent.
6. An Alloy in accordance with claim 1 wherein the range of Hf is up to 1 weight percent.
7. An Alloy in accordance with claim 1 wherein the range of Mn is up to 3.38 weight percent.
8. An Alloy in accordance with claim 1 wherein the range of Mo is up to 0.52 weight percent.
9. An Alloy in accordance with claim 1 wherein the range of Nb is up to 2 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 to 3.49 weight percent.
12. An Alloy in accordance with claim 1 wherein the range of W is up to 0.06 weight percent.
13. An Alloy in accordance with claim 1 wherein the range of Zr is up to 0.02 weight percent.
14. An Alloy in accordance with claim 1 wherein the range of C is 0.18 to 0.24 weight percent.
15. An Alloy in accordance with claim 1 wherein, in terms of atomic percent, 8.7≦Al+Ti+Zr+Hf+Ta≦11.48.
16. An Alloy in accordance with claim 15 wherein, in terms of atomic percent, 9≦Al+Ti+Zr+Hf+Ta≦11.45.
17. An Alloy in accordance with claim 1 wherein, in terms of atomic percent, 0.54≦Al÷(Al+Ti+Zr+Hf+Ta)≦0.64.
18. An Alloy in accordance with claim 17 wherein, in terms of atomic percent, 0.55≦Al÷(Al+Ti+Zr+Hf+Ta)≦0.63.
19. An Alloy in accordance with claim 1 wherein, in terms of atomic percent, 0.17≦Cr÷(Ni+Fe+Cr+Mn)≦0.20.
20. An Alloy in accordance with claim 19 wherein, in terms of atomic percent, 0.18≦Cr÷(Ni+Fe+Cr+Mn)≦0.19.