JP5763062B2 - Nickel-base superalloy composition and superalloy article - Google Patents

Description

  The present invention relates generally to nickel-base superalloy compositions and superalloy articles, and more specifically to such alloys for use in high pressure turbine (HPT) nozzle applications.

  Currently known rhenium-free superalloys may exhibit inappropriate stress fracture properties. Other known superalloys with the desired stress rupture properties may contain relatively high amounts of rhenium. It is desirable to have an alloy that can provide sufficient stress fracture properties at low rhenium levels.

  The above needs can be met by exemplary embodiments that provide nickel-base superalloy compositions for use in high temperature applications. Exemplary embodiments exhibit sufficient stress fracture properties at relatively low or rhenium-free levels.

  In an exemplary embodiment, the superalloy composition comprises, by weight, about 6.2-6.6 aluminum (Al), about 6.5-7.0 tantalum (Ta), about 6.0. -7.0 chromium (Cr), about 6.25-7.0 tungsten (W), about 1.5-2.5 molybdenum (Mo), about 0.15-0.60 hafnium (Hf) ), 0.0-1.0 rhenium (Re), 6.5-9.0 cobalt (Co), optionally 0.03-0.06 carbon (C), optionally maximum One or more rare earth elements selected from up to about 0.004 boron (B), optionally up to a total of up to about 0.03 yttrium (Y), lanthanum (La) or cerium (Ce) And the balance nickel (Ni), the superalloy composition having a nominal weight percentage of 6.5 Al, 6.6 a, Reference Stress Rupture of a Base Composition Containing 6.0, Cr, 6.25 W, 1.5 Mo, 0.15 Hf, 0.0 Re, 7.5 Co, balance nickel It exhibits an improvement in stress rupture properties that exceeds the properties by at least about 15%.

  In an exemplary embodiment, the superalloy composition comprises, by weight, about 6.2-6.6 aluminum (Al), about 6.5-7.0 tantalum (Ta), about 6.0. Chromium (Cr), about 6.25 to 7.0 tungsten (W), about 2.0 molybdenum (Mo), about 0.6 hafnium (Hf), 0.0 to 0.5 rhenium ( Re), about 7.5 cobalt (Co), optionally 0.03-0.06 carbon (C), optionally up to about 0.004 boron (B), optionally Totally up to about 0.03 of one or more rare earth elements selected from yttrium (Y), lanthanum (La) or cerium (Ce) and the balance nickel (Ni) and associated impurities.

  In an exemplary embodiment, an article formed of an exemplary superalloy composition is provided. The article can be a high pressure turbine nozzle, nozzle segment, or other gas turbine engine component.

  The subject matter regarded as the invention is particularly pointed out and distinctly claimed in the claims appended hereto. The invention may best be understood, however, by reference to the following description taken in conjunction with the accompanying drawing figures.

1 is a perspective view of a component article such as a gas turbine engine high pressure turbine (HPT) nozzle segment. FIG.

  Referring now to the drawings, FIG. 1 shows an HPT nozzle segment 10 that includes at least one vane 12. In the exemplary embodiment, nozzle segment 10 includes a single crystal nickel-base superalloy composition as disclosed herein. Articles incorporating the disclosed superalloy compositions include HPT nozzles or nozzle segments and can include other gas turbine engine components.

  Exemplary nickel-base superalloy compositions include low levels of rhenium (Re), defined herein as 0 to up to about 0.5 wt%. Lower levels of Re can be compensated by utilizing a large amount of other strengthened alloy elements such as tantalum (Ta), tungsten (W) and molybdenum (Mo). For example, tantalum can be present in an amount of about 6.5 to about 7.0 weight percent, molybdenum can be present in an amount of about 1.5 to about 2.5 weight percent, and tungsten Can be present in an amount of about 6.25 to about 7.0 weight percent. In other exemplary embodiments, tantalum can be present at a level of about 6.5 to about 6.6% by weight. All percentages (%) given herein are percentages by weight (%) unless otherwise noted.

  Table 1 shows a series of exemplary compositions. The theoretical stress rupture predictions made by computer modeling for these compositions were compared to the predicted stress rupture (within a few hours) of the basic rhenium-free superalloy composition. As can be seen in Table 1, each of the listed compositions exhibited an improvement in predicted stress rupture expressed as a percent improvement.

  Some of the exemplary compositions shown in Table 1 are highlighted. These exemplary compositions show an excellent improvement in predicted stress rupture compared to the base composition. These exemplary compositions can achieve the desired results at low rhenium levels (0.0-0.5 wt%). Other exemplary compositions include rhenium at levels up to about 1.0% by weight.

  Alloys 25 and 27 listed in Table 1 are given as comparative examples and contain about 1.5% by weight rhenium. The exemplary embodiments disclosed herein consider the contribution of various alloying elements to the thermomechanical properties and oxidation resistance of superalloy compositions.

  Some exemplary embodiments disclosed herein comprise about 6.2 to about 6.6% aluminum by weight. In other exemplary embodiments, aluminum can be present in an amount of about 6.3 to about 6.5%.

  Some embodiments disclosed herein are at least about 6 to about 7 weights sufficient to obtain high temperature corrosion resistance, but not high enough to exacerbate TCP phase instability and reduce cyclic oxidation resistance. % Chromium (Cr).

  Some embodiments disclosed herein comprise about 6.5% to about 9%, and more preferably about 7% to about 8% cobalt (Co). Lower amounts of cobalt can reduce alloy stability. Larger amounts can lower the gamma prime solvus temperature and thus affect high temperature strength and oxidation resistance.

  Some embodiments disclosed herein comprise molybdenum (Mo) in an amount of about 1.5-2.5% by weight. The minimum value is sufficient to provide solid solution strengthening. An amount exceeding the maximum value may cause surface instability. Larger amounts of Mo can also adversely affect both high temperature corrosion resistance and oxidation resistance.

  Some embodiments disclosed herein comprise tungsten (W) in an amount of about 6.25 to about 7.0% by weight. Lower amounts of W can reduce strength. Higher amounts can cause instability with respect to TCP phase formation. Higher amounts can also reduce the oxidation properties.

  Some embodiments disclosed herein comprise low levels of rhenium, preferably 0.0 to about 1.0 wt%, and more preferably no greater than about 0.5 wt%. It is believed that some or all of rhenium may be added as a return element from scrap material. Compositions 25 and 27 show a significant improvement in predicted stress rupture properties with the addition (addition) of 1.5 wt% rhenium. It is desirable to obtain performance improvements at low rhenium levels.

  Hafnium (Hf) can be included at relatively low levels, from about 0.15 wt% to higher levels up to about 0.6 wt%. Hafnium can improve the oxidation resistance and adhesion of the heat insulating coating when the coating is used. However, hafnium can reduce the corrosion resistance of uncoated alloys. Addition of about 0.7% hafnium can be satisfactory, but additions greater than about 1% adversely affect stress rupture properties and initial melting temperature.

  Optional additions include about 0.03 to 0.06 wt% carbon (C), up to about 0.004 wt% boron (B), or up to about 0.03 wt% yttrium ( Y), one or more rare earth elements such as lanthanum (La) or cerium (Ce) may be included.

  Boron provides strength to small tilt grain boundaries and increases tolerance limits for components having small tilt grain boundaries. The lower limit of carbon provides sufficient carbon and improves the cleanliness of the alloy because carbon provides deoxidation. If the amount exceeds 0.06% upward, the carbonized body volume fraction increases and the fatigue life is reduced. The addition of rare earths, ie yttrium (Y), lanthanum (La) or cerium (Ce) can be done in amounts up to about 0.03% by weight in some embodiments. These additions can improve oxidation resistance by enhancing retention of the protective alumina scale. Larger amounts can promote tool / metal interaction at the casting surface (casting surface) and increase component-mediated content.

  The exemplary embodiments disclosed herein include each of the compositions listed in Table 1, with the exception of the base composition and comparative alloys 25 and 27. Further, the exemplary embodiments disclosed herein include compositions that employ the endpoints of the disclosed range and all intermediate values. For example, a range of about 6.2 to about 6.6% by weight aluminum includes 6.2% by weight, 6.6% by weight, and any intermediate percent between 6.2 and 6.6% by weight. Defined.

  The exemplary embodiments disclosed herein include a nominal weight percent of 6.5 Al, 6.6 Ta, 6.0 Cr, 6.0, identified as “Base” in Table 1. A stress of at least 15% compared to the baseline stress rupture properties of the base composition containing 25 W, 1.5 Mo, 0.15 Hf, 0.0 Re, 7.5 Co, and the balance nickel. This leads to improved fracture characteristics.

  Example

Alloy：合金
% Improved：％向上
base：基本
All :Balance Ni：全て残部のＮｉ
Alloy 25 and 27 include 1.5 weight % Rhenium as comparative：合金２５及び２７は、比較として１．５重量％のレニウムを含む

本明細書は最良の形態を含む実施例を使用して、本発明を開示し、また当業者が本発明を製作しかつ使用することを可能にする。本発明の特許性がある技術的範囲は、特許請求の範囲によって定まり、また当業者が想到するその他の実施例を含むことができる。そのようなその他の実施例は、それらが特許請求の範囲の文言と相違しない構造的要素を有するか又はそれらが特許請求の範囲の文言と本質的でない相違を有する均等な構造的要素を含む場合には、特許請求の範囲の技術的範囲内に属することになることを意図している。

Alloy: Alloy
% Improved:% improvement
base: Basic
All: Balance Ni: All remaining Ni
Alloy 25 and 27 include 1.5 weight% Rhenium as comparative: Alloys 25 and 27 contain 1.5 weight% rhenium as a comparison

This written description uses examples, including the best mode, to disclose the invention and to enable any person skilled in the art to make and use the invention. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other embodiments may have structural elements that do not differ from the language of the claims, or they contain equivalent structural elements that have non-essential differences from the language of the claims. Is intended to fall within the scope of the appended claims.

10 HPT nozzle segment 12 Vane

Claims (8)

A superalloy composition comprising:
By weight, 6.5 aluminum (Al), 6.6 tantalum (Ta), 6.0-7.0 chromium (Cr), 6.25 tungsten (W), 1.5 molybdenum ( Mo), 0.60 hafnium (Hf), 1.0 rhenium (Re), 7.5 cobalt (Co), optionally 0.03-0.06 carbon (C), optionally One or more rare earth elements selected from up to 0.004 boron (B), optionally up to 0.03 total yttrium (Y), lanthanum (La) or cerium (Ce) , And the balance nickel (Ni) , and accompanying impurities ,
The superalloy composition has a nominal weight percentage of 6.5 Al, 6.6 Ta, 6.0 Cr, 6.25 W, 1.5 Mo, 0.15 Hf,. An improvement in stress rupture properties of at least 15% over the baseline stress rupture properties of the basic composition comprising 0 Re, 7.5 Co, and the balance nickel,
Superalloy composition.
A superalloy composition comprising:
6.5 % by weight of aluminum (Al), 6.6 of tantalum (Ta) , 0 chromium (Cr), 6 . 25 Tungsten (W), 1 . 5 molybdenum (Mo) , 0 . 6 hafnium (Hf), 1.0 rhenium (Re) , 7 . 5 of cobalt (Co), optionally 0.03 to 0.06 carbon (C), optionally up to 0. Boron up to 004 (B), 0 up to the entire optionally. Consisting of up to 03 yttrium (Y), one or more rare earth elements selected from lanthanum (La) or cerium (Ce), the balance nickel (Ni), and associated impurities,
Superalloy composition. An article formed of the superalloy composition according to claim 1. The article of claim 3 comprising a gas turbine engine component. The article of claim 4 comprising a high pressure turbine nozzle or nozzle segment. An article formed of the superalloy composition according to claim 2 . The article of claim 6 , comprising a gas turbine engine component. The article of claim 7 comprising a high pressure turbine nozzle or nozzle segment.

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