Sulfidation resistant nickel-iron base alloy
AssigneeCarpenter Technology Corporation
InventorsC. Raymond Whitney, Andrew R. Walsh
Life of this patent
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Abstract
A sulfidation-resistant alloy containing about 0.02-0.08 w/o carbon, 21-24.5 w/o chromium, 52-60 w/o nickel, 1-3.5 w/o molybdenum, 1.75-3.25 w/o titanium, 0.75-2.25 w/o aluminum, 0.50-2 w/o columbium, up to 0.02 w/o boron and the balance iron, the elements being balanced to provide an average electron-vacancy number Nv not greater than 2.54. When so balanced, the alloy is stabilized against the formation of no more than 10 v/o Cr-rich alpha phase. Preferably, the elements are balanced so that Nv is not greater than 2.45 and better yet not greater than 2.40.
Claims4
An austenitic nickel-iron base alloy resistant to sulfidation at elevated temperatures of about 1200-1500 F., which has good hot strength and stress rupture life at elevated temperatures up to about 1500 F. when heat treated, as well as thermal stability as indicated by freedom from the formation of more than 10 v/o chromium-rich alpha phase when exposed to temperatures of from about 1200-1500 F. for about 1500 hours, said alloy consisting essentially by weight of about
- ______________________________________ w/o ______________________________________ C 0.02-0.08 Mn 2 Max. Si 0.25 Max. P 0.03 Max. S 0.03 Max. Cr 21-24.5 Ni 52-60 Mo 1-3.5 Ti 1.75-3.25 Al 0.75-2.25 Cb 0.50-2 B up to 0.02 ______________________________________
- the balance being essentially iron, and said alloy being balanced so as to have an average electron-vacancy number Nv not greater than 2.50.
Dependencies are inferred from the claim text.