JP2007191791A - Nickel-based superalloy composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a material having a reduced density and also having properties that are suitable for use on conditions that the low pressure turbine section of a gas turbine engine is operated. <P>SOLUTION: The nickel-based alloy composition contains, by weight, from about 8 to about 18% cobalt, from about 12 to about 16% chromium, from about 4 to about 8% aluminum, up to about 6% tungsten, from about 0.5 to about 3.5% titanium, from about 2 to about 6% molybdenum, from about 0.05 to about 0.25% carbon, from about 0.005 to about 0.025% boron, from about 0.02 to about 0.1% zirconium, up to about 1.0% iron, up to about 2.0% rhenium, up to about 2.0% tantalum, up to about 1.0% hafnium and the balance nickel with incidental impurities. The sum weight percent of aluminum and titanium is from about 4.5 wt.% to about 13 wt.%. Further, the ratio of the weight percentage of aluminum to titanium is larger than about 1:1, preferably larger than about 2:1. <P>COPYRIGHT: (C)2007,JPO&amp;INPIT

Description

  The present invention relates to nickel-base superalloy compositions. Specifically, the present invention relates to nickel-base superalloy compositions for gas turbine engine components such as low pressure turbine blades and stationary blade segments used in gas turbine engines.

  In a gas turbine engine, air is pressurized by a compressor and mixed with a fuel and ignited by a combustor to generate high-temperature combustion gas. Hot combustion gases flow into the turbine section of the engine. The turbine section of an engine typically includes multiple stages that include a combination of turbine blades and turbine vanes. The expanded combustion gas comes into contact with the moving blades to rotate the turbine shaft, thereby driving the turbine. The rotation of the turbine shaft is used to power a compressor or other engine parts or accessories. The vane typically includes an airfoil and directs the combustion gas to the turbine blade in the next stage of the turbine. These combustion gases expose turbine blades and vanes to hot corrosive atmospheres.

  The turbine blades and vanes of a gas turbine engine can be made from a nickel-base superalloy. As used herein, “nickel-based” and other like terms mean that the composition contains the most nickel than other elements. For example, alloys such as RENE (R) 80 and RENE (R) 77 may be used for turbine blades and vanes in the low pressure turbine section of a gas turbine engine. The compositions of RENE® 80 and RENE® 77 are known and are used in the manufacture of various gas turbine engine components. RENE® is a trademark of Teledyne Industries, Inc. (Los Angeles, Calif.) For superalloys. RENE® 77 and RENE® 80 typically have the following nominal composition (in weight percent):

ＲＥＮＥ（登録商標）７７及びＲＥＮＥ（登録商標）８０のようなニッケル基超合金は、それらで得られる特性の組合せのゆえにガスタービンエンジン部品に用いられている。これらのニッケル基超合金の使用に伴う短所の一つは、それらの密度が比較的高いことである。密度が高いとガスタービンエンジンの総重量に影響する。例えば、公知のガスタービンエンジンでは、低圧タービンセクションは６〜７段の動翼と静翼を備えていることがある。あるタイプのエンジンでは、最初の２段の動翼と静翼はＲＥＮＥ（登録商標）８０製から製造され、次の４段はＲＥＮＥ（登録商標）７７から製造される。ＲＥＮＥ（登録商標）８０及びＲＥＮＥ（登録商標）７７を低圧タービンセクションに使用すると、タービンセクションが比較的重くなり、エンジンの総重量に影響する。

Nickel-based superalloys such as RENE® 77 and RENE® 80 are used in gas turbine engine components because of the combination of properties obtained with them. One disadvantage associated with the use of these nickel-base superalloys is their relatively high density. High density affects the total weight of the gas turbine engine. For example, in known gas turbine engines, the low pressure turbine section may include 6-7 stages of blades and vanes. In one type of engine, the first two stages of blades and vanes are manufactured from RENE® 80 and the next four stages are manufactured from RENE® 77. When RENE® 80 and RENE® 77 are used in a low pressure turbine section, the turbine section becomes relatively heavy and affects the total weight of the engine.

  Aircraft and aircraft engine designs have continually reduced weight and increased efficiency. Aircraft are becoming larger and require increased engine thrust or additional engines. Maintenance and reduction of manufacturing costs can be achieved by increasing the size of the engine and increasing the thrust generated by the engine. However, as the engine size increases, all engine components in the engine must be increased in size, so weight reduction is the most important issue. Furthermore, the total weight of the aircraft also increases when an additional engine is provided on the aircraft to provide sufficient thrust. To compensate for these problems, materials should be selected that minimize the weight while maintaining the properties required for gas turbine engine operation. If individual parts can be reduced in weight through the use of low-density alloys, there will be significant benefits in reducing engine efficiency, engine durability, payload capacity and fuel costs, as well as other benefits associated with reducing total engine weight. . A disadvantage in the use of previous low density alloys is that the low density alloys do not have the combination of properties required for use in the severe high temperature conditions encountered in the turbine section of gas turbine engines.

Another attempt to reduce the weight of the engine is to replace gas turbine engine components with lightweight non-metallic materials such as epoxy composites. These materials are lightweight and provide desirable mechanical properties, especially in the cold part of the engine. However, these materials do not provide the combination of properties required for gas turbine engine components that are exposed to a hot corrosive atmosphere, such as the low pressure turbine portion of the engine.
US Pat. No. 6,926,754 US Pat. No. 6,905,559 US Pat. No. 6,730,264 US Pat. No. 5,823,243 US Pat. No. 5,270,122 US Pat. No. 5,019,334 US Patent Application Publication No. 2005/0178480 US Patent Application Publication No. 2004/0202569 US Patent Application Publication No. 2003/0051780 European Patent Application No. 1561830 JP 54-101005 A Japanese Patent Laid-Open No. 10-030404 International Publication No. 03/097888 Pamphlet International Publication No. 02/26015 Pamphlet International Publication No. 01/64964 Pamphlet

  Accordingly, there is a need for materials suitable for use in the turbine section of a gas turbine engine that have low density and combine properties suitable for use under conditions present in the low pressure turbine section of a gas turbine engine.

  The present invention is a nickel-based alloy composition comprising about 8-18 wt% cobalt, about 12-16 wt% chromium, about 4-8 wt% aluminum, about 6 wt% or less tungsten, 5 to 3.5 wt% titanium, about 2 to 6 wt% molybdenum, about 0.05 to 0.25 wt% carbon, about 0.005 to 0.025 wt% boron, about 0.02 ~ 0.1 wt% zirconium, about 1.0 wt% or less iron, about 2.0 wt% or less rhenium, about 2.0 wt% or less tantalum, about 1.0 wt% or less hafnium, the balance And an alloy composition in which the total weight percentage of aluminum and titanium is about 4.5 to 13% by weight. Further, the aluminum / titanium weight percent ratio is greater than about 1: 1, preferably greater than about 2: 1. Further, the alloy has characteristics including, but not limited to, stress rupture life, fatigue strength, oxidation resistance and hot corrosion resistance. These properties are equivalent to or better than conventional equiaxed polycrystalline nickel-base superalloys such as RENE® 77 and RENE® 80.

  The invention also includes gas turbine engine components including, but not limited to, compressor blades, compressor vanes, turbine vanes and turbine blades. Gas turbine engine components made from the nickel-base superalloy of the present invention have low density and reduce the overall weight of the engine, but provide sufficient mechanical properties and oxidation / corrosion resistance for use in the applications described above.

  The present invention encompasses low density nickel-base superalloys and products thereof having the compositions (in weight percent units) shown in Table 2.

本発明の別の実施形態は、表３に示す組成（重量％単位）を有する低密度ニッケル基超合金及びその製品を包含する。

Another embodiment of the present invention includes low density nickel-base superalloys and products thereof having the compositions (in weight percent units) shown in Table 3.

本発明のニッケル基超合金には、慣用法で鋳造される等軸多結晶ミクロ組織含有合金が包含される。合金は、表２及び表３に示す合金組成物を真空溶解して溶湯を慣用法で鋳造することによって成形できる。次いで、γ相マトリックス中で望ましいγ′相を析出させるため熱処理を用いてもよい。本発明の合金を成形するための鋳造法としては、慣用のインベストメント鋳造法が挙げられ、ＲＥＮＥ（登録商標）７７及びＲＥＮＥ（登録商標）８０のような従来の等軸多結晶ニッケル基超合金と同等又はそれらよりも優れた応力破断寿命、疲れ強さ、耐酸化性及び耐高温腐食性を与えるのに十分なγ′相を有する実質的に等軸の多結晶合金が得られる。

The nickel-base superalloy of the present invention includes an equiaxed polycrystalline microstructure-containing alloy cast by a conventional method. The alloy can be formed by melting the alloy compositions shown in Table 2 and Table 3 in a vacuum and casting the molten metal by a conventional method. A heat treatment may then be used to precipitate the desired γ 'phase in the γ phase matrix. Casting methods for forming the alloys of the present invention include conventional investment casting methods such as conventional equiaxed polycrystalline nickel-based superalloys such as RENE® 77 and RENE® 80; A substantially equiaxed polycrystalline alloy having a γ 'phase sufficient to provide equivalent or better stress rupture life, fatigue strength, oxidation resistance and hot corrosion resistance is obtained.

  One advantage of the present invention is that the density of the nickel-base superalloy of the present invention is lower than the density of nickel-base superalloys previously used in the turbine section of gas turbine engines.

  Another advantage of the present invention is that the nickel-base superalloy composition retains an aluminum / titanium ratio that provides sufficient aluminum to form an aluminum oxide-containing coating on the alloy surface, while the gamma prime phase can be formed. It protects the alloy from oxidation and hot corrosion and forms a suitable surface for additional coatings.

  Yet another advantage of the present invention is that the properties of the alloy are comparable or superior to substantially equiaxed conventional casting alloys such as RENE® 77 and RENE® 80. It is. The mechanical properties and oxidation / corrosion resistance of RENE (R) 77 and RENE (R) 80 are equal to or superior to those of turbine engine components while maintaining or increasing operating parameters of the gas turbine engine. Can be replaced with low density material.

  Yet another advantage of the present invention is that gas turbine engines manufactured using the alloys of the present invention are lighter, particularly providing significant advantages in reducing engine efficiency, engine durability, payload capacity and fuel consumption. It is.

  Other features and advantages of the present invention will become apparent from the detailed description of the preferred embodiments given to illustrate the principles of the invention.

  The present invention includes a low density nickel-base superalloy for gas turbine engine components. In particular, the present invention includes gas turbine engine turbine blades and vanes manufactured from low density nickel-base superalloys.

  One embodiment of the present invention includes about 8-11% cobalt, about 12-16% chromium, about 4-8% aluminum, about 4-6% tungsten, about 0.5-3 5 wt% titanium, about 2-6 wt% molybdenum, about 0.05-0.25 wt% carbon, about 0.005-0.025 wt% boron, about 0.02-0.1 Includes nickel-base superalloys containing weight percent zirconium, less than about 2.0 weight percent rhenium, less than about 2.0 weight percent tantalum, less than about 1.0 weight percent hafnium, the balance nickel and inevitable impurities. .

  Other embodiments of the invention include about 12-18% cobalt, about 13-16% chromium, about 4-8% aluminum, about 1-3% titanium, about 2-6% % Molybdenum, about 0.05-0.25 wt% carbon, about 0.005-0.025 wt% boron, about 0.01-0.1 wt% zirconium, up to about 1.0 wt% A nickel-base superalloy containing about 2.0 wt% or less rhenium, about 2.0 wt% or less tantalum, about 1.0 wt% or less hafnium, the balance nickel and unavoidable impurities.

  The nickel-base superalloy according to an embodiment of the present invention is preferably a composition having a lower density than a conventional equiaxed polycrystalline microstructure cast alloy. The alloys of the present invention include alloys having a substantially equiaxed polycrystalline microstructure cast by conventional methods. To mold the alloy, the elemental composition is first dissolved. Melting for casting can be performed using any suitable melting process, including vacuum induction melting or vacuum arc melting. Additional remelting steps may be provided to remove impurities from the melt, including additional vacuum arc remelting, electroslag remelting, and combinations thereof. Next, heat treatment may be performed to obtain a desired microstructure. In one embodiment of the invention, low density is obtained by keeping the aluminum / titanium weight ratio of the alloy composition greater than about 1: 1. This ratio preferably has a lower limit large enough to give a low density alloy and an upper limit low enough to give a nickel-base superalloy having the predetermined properties.

The ratio and total amount of aluminum and titanium are defined such that the amount of γ 'phase precipitation in the alloy matrix is increased compared to conventional cast alloys. The γ 'phase precipitates typically contain Ni ₃ (Al, Ti) or Co ₃ (Al, Ti) and provide the main strengthening phase of the alloy without significantly reducing the fracture toughness of the alloy. As the amount of titanium and aluminum increases, the amount of titanium and aluminum available to form the γ 'phase also increases. Furthermore, the higher the aluminum / titanium ratio, the greater the amount of γ 'phase present in the alloy matrix. The presence of the γ 'phase provides desirable properties for alloys used in gas turbine engine components. The nickel-base superalloy preferably has a total weight percentage of aluminum and titanium greater than about 5% by weight. By combining the total amount of aluminum and titanium in addition to the aluminum / titanium ratio, the density of the alloy can be made lower than conventional cast alloys such as RENE® 80 and RENE® 77.

  In addition to increasing the abundance of the γ 'phase and decreasing the alloy density, increasing the amount of aluminum and increasing the aluminum / titanium ratio, preferably greater than about 1: 1, will result in excess aluminum being aluminum oxide on the outer surface of the alloy. It becomes possible to use it for formation of a content layer. These oxide-containing layers not only provide protection from the atmosphere, provide oxidation resistance and hot corrosion resistance, but also form a surface suitable for providing additional coatings such as thermal barrier coatings. Excess aluminum also provides self-healing film properties in which the aluminum oxide-containing film regenerates at damaged or eroded surface sites.

  In another embodiment of the present invention, a strengthening element may be added to the alloy composition. High density elements such as W and Mo greatly increase the weight of the entire component made of nickel-base superalloy. The concentration of these high density elements can be reduced by the addition of small amounts of strengthening elements including Re, Ta, Hf and combinations thereof. The addition of Re, Ta, Hf and combinations thereof increases the strength of the material. Ta and Hf present in the alloy further strengthen the alloy by solid solution strengthening of the γ 'phase. Re present in the alloy further strengthens the alloy by solid solution strengthening of the γ matrix. When a relatively small amount of these strengthening elements is added, the amount of W and Mo used in the alloy composition can be reduced. The reduction of W and Mo and the ability to strengthen the alloy composition with a small amount of strengthening elements such as Re, Ta and Hf have the effect of lowering the alloy density as a whole. The W concentration of the alloy can be reduced to 2% by introducing these alternative strengthening elements. The Mo concentration of the alloy can be reduced or completely eliminated by the introduction of these alternative strengthening elements. In a preferred embodiment, replacing W and / or Mo with these alternative strengthening elements further reduces the alloy density by 2% over the alloys having the Al: Ti ratio of the present invention.

Example 1

表４に、ＲＥＮＥ（登録商標）８０の公称組成を有する比較例１と、標記の量のＴｉ及びＡｌを有する実施例１を示す。アルミニウムとチタンはいずれもγ′形成元素であり、γ′相組織を形成して合金を強化する。比較例１は５重量％のＴｉと３重量％のＡｌを含み、密度は０．２９５ｌｂｓ／ｉｎ^３である。実施例１のニッケル基超合金は約９．５重量％のコバルト、約１４重量％のクロム、約６重量％のアルミニウム、約４重量％のタングステン、約２重量％のチタン、約４重量％のモリブデン、約０．１７重量％の炭素、約０．０１５重量％のホウ素、約０．０３重量％のジルコニウム、残部のニッケル及び不可避不純物を含む。実施例１はＡｌ＋Ｔｉの合計８重量％、Ａｌ：Ｔｉ比約３：１である。表４に示すように、実施例１の密度は０．２８７ｌｂｓ／ｉｎ^３である。実施例１の密度は、比較例１の密度よりも約３％低い。合金密度の３％の低下は、組立後のエンジンの総重量の約８１ｌｂｓ以上の低減に相当する。この密度低下によって、実施例１の合金から製造した部品の総重量は大幅に低減される。

Table 4 shows Comparative Example 1 having a nominal composition of RENE® 80 and Example 1 having the indicated amounts of Ti and Al. Aluminum and titanium are both γ′-forming elements and form a γ ′ phase structure to strengthen the alloy. Comparative Example 1 contains 5% by weight of Ti and 3% by weight of Al, the density is 0.295lbs / in ^3. The nickel-base superalloy of Example 1 is about 9.5 wt% cobalt, about 14 wt% chromium, about 6 wt% aluminum, about 4 wt% tungsten, about 2 wt% titanium, about 4 wt% Molybdenum, about 0.17 weight percent carbon, about 0.015 weight percent boron, about 0.03 weight percent zirconium, the balance nickel and inevitable impurities. Example 1 has a total of 8% by weight of Al + Ti and an Al: Ti ratio of about 3: 1. As shown in Table 4, the density of Example 1 is 0.287 lbs / in ³ . The density of Example 1 is about 3% lower than the density of Comparative Example 1. A 3% decrease in alloy density corresponds to a reduction of about 81 lbs or more in the total weight of the engine after assembly. This reduction in density significantly reduces the total weight of parts made from the alloy of Example 1.

Example 2

表５に、実施例２のチタンとアルミニウムの相対的存在量及び密度を、ＲＥＮＥ（商標）７７の公称組成をもつ比較例２の密度と対比して示す。比較例２は、３．３５重量％のＴｉと４．３重量％のＡｌを含み、密度は０．２８６ｌｂｓ／ｉｎ^３である。実施例２のニッケル基超合金は、約１５重量％のコバルト、約１４．３重量％のクロム、約６重量％のアルミニウム、約３重量％のチタン、約４．２重量％のモリブデン、約０．０７重量％の炭素、約０．０１５重量％のホウ素、約０．０４重量％のジルコニウム及び０．５重量％の鉄を含む。実施例２はＡｌ＋Ｔｉの合計９重量％、Ａｌ：Ｔｉ比約２：１、密度０．２７９ｌｂｓ／ｉｎ^３である。実施例２の密度は、比較例２の密度よりも約３％低い。合金密度の３％の低下は、組立後のエンジンの総重量の約８１ｌｂｓ以上の低減に相当する。この密度低下によって、実施例２の合金から製造した部品の総重量は大幅に低減される。

Table 5 shows the relative abundance and density of titanium and aluminum of Example 2 as compared to the density of Comparative Example 2 having a nominal composition of RENE ™ 77. Comparative Example 2 contains 3.35 wt% Ti and 4.3 wt% Al and has a density of 0.286 lbs / in ³ . The nickel-base superalloy of Example 2 has about 15 wt% cobalt, about 14.3 wt% chromium, about 6 wt% aluminum, about 3 wt% titanium, about 4.2 wt% molybdenum, about Contains 0.07 wt% carbon, about 0.015 wt% boron, about 0.04 wt% zirconium and 0.5 wt% iron. Example 2 has a total of 9% by weight of Al + Ti, an Al: Ti ratio of about 2: 1, and a density of 0.279 lbs / in ³ . The density of Example 2 is about 3% lower than the density of Comparative Example 2. A 3% decrease in alloy density corresponds to a reduction of about 81 lbs or more in the total weight of the engine after assembly. This reduction in density significantly reduces the total weight of parts made from the alloy of Example 2.

  In a gas turbine engine having a six-stage low-pressure turbine such as GE-92B, the high-density RENE (registered trademark) 77 and the RENE (registered trademark) 80 of Comparative Examples 1 and 2 are used as the low-density alloys of Examples 1 and 2. Replacing leads to a weight reduction of about 81 lbs, and the gas turbine engine is significantly reduced in weight.

  Although the invention has been described with reference to preferred embodiments, it will be apparent to those skilled in the art that various modifications can be made and elements can be substituted with equivalents within the scope of the invention. In addition, many modifications may be made to adapt a particular state or material to the teachings of the invention within the scope of the invention. Therefore, the present invention is not limited to the specific embodiment disclosed as the best mode, and includes all the embodiments belonging to the claims.

Claims (10)

A nickel-based alloy composition having a substantially equiaxed polycrystalline microstructure,
About 8-18% cobalt, about 12-16% chromium, about 4-8% aluminum, up to about 6% tungsten, about 0.5-3.5% titanium, about 2% ~ 6 wt% molybdenum, about 0.05 to 0.25 wt% carbon, about 0.005 to 0.025 wt% boron, about 0.02 to 0.1 wt% zirconium, about 1.0 Containing no more than wt% iron, no more than about 2.0 wt% rhenium, no more than about 2.0 wt% tantalum, no more than about 1.0 wt% hafnium, the balance nickel and inevitable impurities,
An alloy composition wherein the total weight percentage of aluminum and titanium is about 4.5-13 wt% and the aluminum / titanium ratio is greater than about 1: 1. The alloy of claim 1, wherein the aluminum / titanium ratio is about 2: 1 or greater. About 8-11 wt% cobalt, about 12-16 wt% chromium, about 4-8 wt% aluminum, about 4-6 wt% tungsten, about 0.5-3.5 wt% titanium, about 2 to 6 wt% molybdenum, about 0.05 to 0.25 wt% carbon, about 0.005 to 0.025 wt% boron, about 0.02 to 0.1 wt% zirconium, about 2. The alloy of claim 1, comprising no more than 0 wt% rhenium, no more than about 2.0 wt% tantalum, no more than about 1.0 wt% hafnium, the balance nickel and inevitable impurities. About 9-10% cobalt, about 13-15% chromium, about 5-7% aluminum, about 3-5% tungsten, about 1-3% titanium, about 3-5% % Molybdenum, about 0.1-0.2% carbon, about 0.010-0.020% boron, about 0.02-0.05% zirconium, up to about 1.0% by weight 4. The alloy of claim 3, comprising less than about 1.0% by weight of rhenium, less than about 1.0% by weight of hafnium, the balance nickel and unavoidable impurities. About 9.5 wt% cobalt, about 14 wt% chromium, about 6 wt% aluminum, about 4 wt% tungsten, about 1 wt% titanium, about 4 wt% molybdenum, about 0.17 wt% 5. The alloy of claim 4, comprising about 0.015% by weight boron, about 0.05% by weight zirconium, the balance nickel and unavoidable impurities. About 12-18% cobalt, about 13-16% chromium, about 4-8% aluminum, about 1-3% titanium, about 2-6% molybdenum, about 0.05- 0.25 wt% carbon, about 0.005-0.025 wt% boron, about 0.01-0.1 wt% zirconium, up to about 1.0 wt% iron, about 2.0 wt% The alloy of claim 1 comprising the following rhenium, no more than about 2.0 wt% tantalum, no more than about 1.0 wt% hafnium, the balance nickel and inevitable impurities. About 13-16 wt% cobalt, about 14-15 wt% chromium, about 5-7 wt% aluminum, about 2-3 wt% titanium, about 3-5 wt% molybdenum, about 0.10 0.20 wt% carbon, about 0.010 to 0.020 wt% boron, about 0.02 to 0.05 wt% zirconium, up to about 0.75 wt% iron, about 1.0 wt% The alloy of claim 6 comprising the following rhenium, up to about 1.0 wt% tantalum, up to about 1.0 wt% hafnium, the balance nickel and inevitable impurities. About 15% cobalt, about 14.3% chromium, about 6% aluminum, about 3% titanium, about 4.2% molybdenum, about 0.07% carbon, about 0% The alloy of claim 7 comprising: .015 weight percent boron, about 0.05 weight percent zirconium, about 0.5 weight percent iron, the balance nickel and unavoidable impurities. The alloy of claim 1, wherein the alloy has a density of less than about 0.287 lbs / in ³ . The alloy of claim 1, wherein the alloy has a density of less than about 0.279 lbs / in ³ .