Alloy for gas turbine applications with high oxidation resistance

Abstract

A nickel base super alloy or blade alloy having Ni as a main constituent and the following elements or portions in wt %: Fe: 2 to 8, Al: 6.1 to 6.8, Cr: 12.5 to 15, W: 1.5 to 4.5, Ta: 2.5 to 5.5, Hf: 1.2 to 2, C: 0.03 to 0.13, B: 0.005 to 0.02, Zr: 0.005 to 0.02, and Si: 0.005 to 0.02.

Claims

1. A nickel base alloy, comprising: Ni as a main constituent, and the following portions in wt %: Fe: 2 to 8, Al: 6.1 to 6.8, Cr: 12.5 to 15, W: 1.5 to 4.5, Ta: 2.5 to 5.5, Hf: 1.2 to 2, C: 0.03 to 0.13, B: 0.005 to 0.02, Zr: 0.005 to 0.02, and Si: 0.005 to 0.02.

2. The alloy according to claim 1, comprising: between 20 and 500 ppmw of an element selected from the group consisting of lanthanum, cerium, yttrium, and combinations thereof.

3. The alloy according to claim 1, comprising: sulfur at a level below 5 ppmw.

4. The alloy according to claim 1, comprising: 1.5 to 3.5 wt % of W, 2.5 to 4.5 wt % of Ta, and 1.4 to 1.8 wt % of Hf.

5. The alloy according to claim 1, comprising 0.03 to 0.09 wt % of C, 0.005 to 0.015 wt % of B and 0.005 to 0.015 wt % of Zr.

6. The alloy according to claim 1, comprising: 5 to 7 wt % of Fe, 6.4 to 6.7 wt % of Al, and 13.5 to 14.5 wt % of Cr.

7. The alloy according to claim 1, comprising: 2 to 4 wt % of Fe, 6.1 to 6.4 wt % of Al, and 13.5 to 14.5 wt % of Cr.

8. The alloy according to claim 1, comprising: 0.005 to 0.015 wt % of Si.

9. The alloy according to claim 1, comprising: 0.005 to 0.015 wt % of Ce, La, Y.

10. The alloy according to claim 1, wherein—aside from unavoidable impurities—the alloy is free of at least one of Co, Mo, Re, Ti and Nb.

11. The alloy according to claim 1, wherein the alloy is configured such that a solvus temperature is suppressed to or lies between 1140° C. and 1165° C.

12. The alloy according to claim 1 consisting of the following constituents: Ni as a main constituent, Fe: 2 to 8 wt %, Cr: 12 to 15 wt %, W: 1.5 to 4.5 wt %, Al: 6.1 to 6.8 wt %, Ta: 2.5 to 5.5 wt %, Hf: 1.2 to 2 wt %, C: 0.03 to 0.13 wt %, B: 0.005 to 0.02 wt %, Zr: 0.005 to 0.02 wt %, Si: 0.005 to 0.02 wt %, between 20 and 500 ppmw of one or more of Y, La, Ce, and between 0.01 and 0.5 wt % of an element selected from the group consisting of Sc, Y, the actinides and the lanthanides.

13. A powder material comprising: an alloy according to claim 1 for the additive manufacture of a structure.

14. A method of additive manufacturing a turbine component from an alloy base material according to claim 1, the method comprising: using laser metal deposition to additively manufacture the turbine component.

15. The alloy according to claim 3, comprising: sulfur at a level below 2 ppmw.

16. The alloy according to claim 4, comprising: 2 wt % of W, 3 wt % of Ta, and 1.5 wt % of Hf.

17. The alloy according to claim 5, comprising: 0.05 to 0.07 wt % of C, 0.01 wt % of B and 0.01 wt % of Zr.

18. The alloy according to claim 6, comprising: 6 wt % of Fe, 6.5 wt % of Al, and 14 wt % of Cr.

19. The alloy according to claim 7, comprising: 3 wt % of Fe, 6.25 wt % of Al, and 14 wt % of Cr.

20. The alloy according to claim 8, comprising: 0.01 wt % of Si.

21. The alloy according to claim 9, comprising: 0.01 wt % of Ce, La, Y.

Description

DETAILED DESCRIPTION OF INVENTION

(1) The novel alloy presented herein is a new blade alloy with a high oxidation resistance and adequate TMF strength with yet favourable hot cracking resistance, at least of and that one of the IN738LC level.

(2) The alloy as described herein facilitates gamma prime precipitation in about the same manner as IN738LC on cooling from the molten state. Specifically, the solvus temperature has been reduced to the same level as in IN738LC to enable the already solidified material to accommodate the solidification strains in the same manner as for IN738LC. A key element here is the use of Fe to suppress the solvus temperature. Additionally, the Hf level is high while the Zr and Si levels are low to e.g. reduce the amount of residual fluid on the grain boundaries during solidification.

(3) In addition or alternative to the above description, the presented alloy may comprise or be composed of nickel as a base constituent and the following portions/elements (prior to the element symbol), advantageously in wt %: 3 Fe, 14 Cr, 2 W, 6.2 Al, 3 Ta, 1.5 Hf, 0.08 C, 0.01 B, 0.01 Zr, 0.01 Si and 0.01 Ce. With 6.2% Al, 3% Ta and 1.5% Hf, the presented alloy is a high γ′-content alloy. Said prominent γ′-content is favorable.

(4) As mentioned above, it is as well possible to further increase the Al and Fe levels to provide an even higher oxidation resistance while having a similar solvus temperature at about 1150° C. Thus, the presented alloy may comprise or be composed of nickel as a base constituent and the following portions/elements (prior to the element symbol), advantageously in wt %: 6 Fe, 14 Cr, 2 W, 6.6 Al, 3 Ta, 1.5 Hf, 0.05 C, 0.01 B, 0.01 Zr, 0.01 Si and 0.01 Ce.

(5) Another possibility is to allow TCP precipitation up to 850° C. and reduce the Cr content to 13.5%, to enable more matrix and particle strengthening. Thus, the presented alloy may comprise or be composed of nickel as a base constituent and the following portions/elements (prior to the element symbol), advantageously in wt %: 6 Fe, 13.5 Cr, 3.5 W, 6.2 Al, 4.5 Ta, 1.5 Hf, 0.05 C, 0.01 B, 0.01 Zr, 0.01 Si and 0.01 Ce.

(6) The scope of protection of the invention is not limited to the examples given hereinabove. The invention is embodied in each novel characteristic and each combination of characteristics, which particularly includes every combination of any features which are stated in the claims, even if this feature or this combination of features is not explicitly stated in the claims or in the examples.