JP2015165048A - Article and method for forming article - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an article including an equiaxed crystal structure and a composition, and a method for forming the article.SOLUTION: An article and a method for forming the article are disclosed. The article includes an equiaxed crystal structure and a composition. The composition includes, by weight percent, about 6.0% to about 9.0% aluminum, up to about 0.5% titanium, about 2.5% to about 4.5% tantalum, about 10.0% to about 12.5% chromium, about 5.0% to about 10.0% cobalt, about 0.30% to about 0.80% molybdenum, about 2.0% to about 5.0% tungsten, up to about 1.0% silicon, about 0.35% to about 0.60% hafnium, about 0.005% to about 0.010% boron, about 0.06% to about 0.10% carbon, up to about 0.02% zirconium, up to about 0.1% lanthanum, up to about 0.03% yttrium, and balance nickel and incidental impurities. Rhenium, if present, is a trace element. The method for forming the article includes preparing the composition having up to about 0.01% rhenium, and forming the article.

Description

  The present invention relates to an article and a method for manufacturing the article. More specifically, the present invention relates to an article comprising an equiaxed crystal structure and a composition and a method for producing the article.

  Gas turbine and aircraft engine hot gas path components, particularly turbine blades, vanes, nozzles, seals and stationary shrouds, operate at high temperatures, often in excess of 2000 ° F. The superalloy composition used to form the hot gas path component is a single crystal composition often blended with a large amount of rhenium (Re) due to the high temperatures and other operating conditions to which the component is exposed in the first stage. It is. Such superalloy compositions typically contain 1-3% by weight rhenium (Re), and some may incorporate up to 6% by weight rhenium (Re).

  One such single crystal rhenium (Re) containing superalloy composition is referred to herein as “N 2 Re”. N 2 Re is, by weight, aluminum (Al) 6.0% to 9.0%, titanium (Ti) 0.5% or less, tantalum (Ta) 4.0% to 6.0%, chromium (Cr) 12 0.5% to 15.0%, Cobalt (Co) 3.0% to 10.0%, Molybdenum (Mo) 0.25% or less, Tungsten (W) 2.0% to 5.0%, Silicon (Si ) 1.0% or less, hafnium (Hf) 0.2% or less, rhenium (Re) 1.0% to 3.0%, and the remaining nickel (Ni) and inevitable impurities. N 2 Re may also include boron (B) 0.01% or less, carbon (C) 0.07% or less, zirconium (Zr) 0.03% or less, and lanthanum (La) 0.1% or less. An example of a composition belonging to the category of N2Re may include an alloy not commercially available under the trademark “Rene N2” (available from General Electric).

  An alternative superalloy composition that is not single crystal and does not contain rhenium (Re) is referred to herein as “R108”. R108 is, by weight, aluminum (Al) 5.25% to 5.75%, titanium (Ti) 0.6% to 0.9%, tantalum (Ta) 2.8% to 3.3%, chromium (Cr) 8.0% to 8.7%, Cobalt (Co) 9.0% to 10.0%, Molybdenum (Mo) 0.4% to 0.6%, Tungsten (W) 9.3% to 9.7%, silicon (Si) 0.12% or less, hafnium (Hf) 1.3% to 1.7%, boron (B) 0.01% to 0.02%, carbon (C) 0.1 % Or less, zirconium (Zr) 0.005% to 0.02%, iron (Fe) 0.2% or less, manganese (Mn) 0.1% or less, copper (Cu) 0.1% or less, phosphorus (P ) 0.01% or less, sulfur (S) 0.004% or less, niobium (Nb) 0.1% or less, and nickel (Ni) and inevitable impurities. An example of a composition within the scope of R108 may include an alloy not commercially available under the trade name “Rene 108”. Under test conditions of 2000 ° F. in a burner rig, the article formed from R108 forms an unstable oxide scale on the surface due to the low chromium content.

  R108 and N2Re have comparable high temperature mechanical properties, but R108 has high temperature corrosion resistance and oxidation resistance that are significantly inferior to N2Re. As a result, R108 is not suitable for making heavy gas turbine or aircraft engine first stage hot gas path components.

  Single crystal superalloys containing rhenium (Re), such as Rene N5, Rene N6 and Rene N2, have good strength, ductility, creep life, low cycle fatigue life, acid resistance under the operating conditions of gas turbines or aircraft engines It can provide highly desirable properties for gas turbine or aircraft engine applications, including oxidizability and hot corrosion resistance. However, rhenium (Re) is one of the most expensive metals, and the processing of single crystal members is typically time consuming and expensive, so rhenium (Re) containing single crystal superalloys are economically Undesirable.

U.S. Pat. No. 8431073

  There is a need in the art for articles and methods that improve the process and / or properties of the parts that are formed.

  In one embodiment, the article comprises an equiaxed crystal structure and composition, wherein the composition is about 6.0% to about 9.0% aluminum (Al) and about 0.5% titanium (Ti) by weight. % Or less, tantalum (Ta) about 2.5% to about 4.5%, chromium (Cr) about 10.0% to about 12.5%, cobalt (Co) about 5.0% to about 10.0% Molybdenum (Mo) about 0.30% to about 0.80%, tungsten (W) about 2.0% to about 5.0%, silicon (Si) about 1.0% or less, hafnium (Hf) about 0 .35% to about 0.60%, boron (B) about 0.005% to about 0.010%, carbon (C) about 0.06% to about 0.10%, zirconium (Zr) about 0.02 % Or less, lanthanum (La) about 0.1% or less, yttrium (Y) about 0.03% or less and the remaining nickel (Ni) and inevitable impurities. Look, but also trace elements as rhenium (Re) was present.

  In another embodiment, a method for manufacturing an article includes the steps of providing a composition and forming the article. The composition comprises, by weight, aluminum (Al) about 6.0% to about 9.0%, titanium (Ti) about 0.5% or less, tantalum (Ta) about 2.5% to about 4.5%. Chromium (Cr) about 10.0% to about 12.5%, cobalt (Co) about 5.0% to about 10.0%, molybdenum (Mo) about 0.30% to about 0.80%, tungsten (W) about 2.0% to about 5.0%, silicon (Si) about 1.0% or less, hafnium (Hf) about 0.35% to about 0.60%, boron (B) about 0.005 % To about 0.010%, carbon (C) about 0.06% to about 0.10%, zirconium (Zr) about 0.02% or less, lanthanum (La) about 0.1% or less, yttrium (Y) It contains about 0.03% or less, rhenium (Re) about 0.01% or less, and the balance nickel (Ni) and inevitable impurities. The article includes an equiaxed crystal structure.

  Other features and advantages of the present invention will become apparent from the following more detailed description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention.

3 is an article cast from RNX according to an embodiment of the present disclosure, including a fine recess of complex geometry. The low cycle fatigue life of articles formed from N2Re, R108 and RNX are compared. The creep life of articles formed from N2Re, R108 and RNX are compared. The oxide layer depth of articles made from R108 and RNX are compared. 2 is a microscopic cross-sectional photograph of an article formed from RNX according to an embodiment of the present disclosure that has undergone a burner rig test. It is a microscope cross-sectional photograph of the corresponding | compatible article formed from R108 which passed the burner rig test.

  Wherever possible, the same reference numbers will be used throughout the drawings to represent the same parts.

  Articles and methods of manufacturing the articles are provided. Embodiments of the present disclosure provide increased corrosion resistance, increased oxidation resistance, increased low cycle fatigue life, increased creep life, and methods and articles that do not use one or more features disclosed herein. Improves castability, increases phase stability at high temperatures, lowers costs, or provides a combination thereof. Embodiments of the present disclosure provide a gas turbine with a rhenium (Re) -free nickel-base superalloy having an equiaxed crystal structure and at least as advantageous properties as a rhenium (Re) -containing nickel-base superalloy And aircraft engine hot gas path components.

  In one embodiment, the article comprises an equiaxed crystal structure and a composition. The composition comprises, by weight, aluminum (Al) about 6.0% to about 9.0%, titanium (Ti) about 0.5% or less, tantalum (Ta) about 2.5% to about 4.5%. Chromium (Cr) about 10.0% to about 12.5%, cobalt (Co) about 5.0% to about 10.0%, molybdenum (Mo) about 0.30% to about 0.80%, tungsten (W) about 2.0% to about 5.0%, silicon (Si) about 1.0% or less, hafnium (Hf) about 0.35% to about 0.60%, boron (B) about 0.005 % To about 0.010%, carbon (C) about 0.06% to about 0.10%, zirconium (Zr) about 0.02% or less, lanthanum (La) about 0.1% or less, yttrium (Y) About 0.03% or less and the balance of nickel (Ni) and inevitable impurities are included. The composition contains rhenium (Re) at all or only as a trace element. In another embodiment, rhenium (Re) is present only in an amount less than 0.01% by weight of the composition.

  In one embodiment, about 2.5% to about 4.5% of tantalum (Ta) in the composition is completely or partially replaced with niobium (Nb) on a 1: 1 molar basis. This replacement does not have a significant effect on the castability or serviceability of the article, but reduces the cost of the composition.

  In another embodiment, the composition comprises, by weight, about 6.2% to about 6.5% aluminum (Al), up to about 0.04% titanium (Ti), and about 3.9% tantalum (Ta). To about 4.3%, chromium (Cr) from about 12.0% to about 12.5%, cobalt (Co) from about 7.0% to about 8.0%, molybdenum (Mo) from about 0.40% to about 0.75%, tungsten (W) about 4.7% to about 5.1%, silicon (Si) about 0.08% to about 0.12%, hafnium (Hf) about 0.47% to about 0.00. 53%, boron (B) about 0.005% to about 0.010%, carbon (C) about 0.06% to about 0.10%, zirconium (Zr) about 0.02% or less, lanthanum (La) About 0.1% or less, yttrium (Y) about 0.03% or less, rhenium (Re) about 0.01% or less, and the remaining nickel (Ni) Including the avoid impurities.

  In one embodiment, the article is a gas turbine or aircraft engine hot gas path component, and the hot gas path component is exposed to a temperature of at least about 2000 degrees Fahrenheit. In another embodiment, the hot gas path component is selected from the group consisting of blades, vanes, nozzles, seals, and stationary shrouds.

  In one embodiment, a method of manufacturing an article includes the steps of providing a composition and forming an article from the composition. In another embodiment, forming the article from the composition includes any suitable technique, including but not limited to casting, powder metallurgy, and three-dimensional additive processing. In another embodiment, the casting includes precision investment casting with variable pressure control.

  As used herein, “precision investment casting with variable pressure control” means the casting process described below. The ingot is heated to surface remelting under surface remelting pressure by an induction coil in the melting chamber. Inert gas is introduced into the dissolution chamber until the casting pressure is reached. The temperature is adjusted until the dissolution temperature is reached. When the ingot is completely converted to a melt, the melt is injected at casting pressure into the mold cavity under an inert gas. The inert gas is maintained at casting pressure until the article is cast into a solid. Other steps in the typical industrial casting process, such as pattern creation, mold preparation and post-injection solidification, are unchanged in precision investment casting with variable pressure control.

In one embodiment, when the ingot is composed of a composition, the precision investment casting with variable pressure control includes a surface remelting pressure of 10 ⁻³ atmospheres and an inert gas casting pressure of 10 ⁻² atmospheres to 10 ⁻¹ atmospheres. In another embodiment, the inert gas is argon (Ar).

  In one embodiment, precision investment casting with variable pressure control minimizes chromium (Cr) loss during melting and casting. Operation of a hot gas path component of a gas turbine or aircraft engine under a temperature of at least about 2000 ° F. is typically at least about 12.0% chromium (by weight) to maintain high temperature corrosion resistance and oxidation resistance. Cr) content is required.

  In one embodiment, the composition is highly castable. As used herein, “high castability” means that there is not a short supply of microstructure features such as surface-enhanced depressions or fine ribs during casting of the composition into the article, coagulation shrinkage is within an acceptable range, As well as indicating that the article is essentially free of mold / metal or core / metal reactions. In another embodiment, the composition may be cast without requiring the use of hot isostatic pressing on a hot gas path component of a gas turbine or aircraft engine that is exposed to a temperature of at least about 2000 degrees Fahrenheit. Provide sufficiently high internal health. Hot isostatic pressing is to close the solidification shrinkage voids inside the cast article and to meet the requirements of hot gas path components of gas turbines or aircraft engines that are exposed to temperatures of at least about 2000 ° F. Widely used to improve mechanical properties. By eliminating the processing step that exposes the cast article to hot isostatic pressing, the manufacturing cost of the cast article is reduced.

  In one embodiment, the surface of an article formed from a composition according to the present disclosure forms a stable aluminum oxide rich scale hot under the operating conditions of a gas turbine or aircraft engine hot gas path. In another embodiment, a stable aluminum oxide-rich scale retards the diffusion of reactive species in an oxidizing atmosphere and improves the oxidation and hot corrosion performance of the composition according to the present disclosure.

  In one embodiment (referred to herein as “RNX”), the composition according to the present disclosure comprises, by weight, 6.25% aluminum (Al), 4.0% tantalum (Ta), chromium (Cr ) 12.5%, cobalt (Co) 7.5%, molybdenum (Mo) 0.5%, tungsten (W) 5.0%, hafnium (Hf) 0.5%, boron (B) 0.0075% , Carbon (C) 0.08% and nickel (Ni) and the balance of incidental impurities.

  In one embodiment, the high castability of the composition to R108 means that an article formed from RNX according to the present disclosure experiences 50% lower solidification shrinkage during casting than a corresponding article formed from R108. Illustrated by comparison.

  Referring to FIG. 1, in one embodiment, an article formed from an RNX according to the present disclosure by a precision investment casting process with variable pressure control has demonstrated high castability of the composition, the article being a high temperature gas turbine Gas passage parts, specifically a 48 pound nozzle. The nozzle includes a plurality of very small depressions having a complex geometry, and the nozzle includes more than about 400 depressions per square inch on a curved inner surface. The depression is formed with high accuracy suitable for use under operating conditions.

  In one embodiment, the tensile properties of an article formed from RNX according to the present disclosure, including yield strength, ultimate strength and ductility, are at least equivalent to the tensile properties of the corresponding article formed from N2Re.

  Referring to FIG. 2, in one embodiment, an article formed from RNX according to the present disclosure is a counterpart formed from N2Re under a test condition of 0.6% strain at 1800 ° F. and a holding time of 2 minutes. About 20% longer, or about 18% to about 22% longer than the corresponding low cycle fatigue life exhibited by the article, and the corresponding low cycle fatigue life exhibited by the corresponding article formed from R108. Also have a low cycle fatigue life that is about 54% longer, or about 50% to about 58% longer.

  Referring to FIG. 3, in one embodiment, an article formed from RNX according to the present disclosure is more than the corresponding creep life exhibited by the corresponding article formed from N 2 Re under the test conditions of 1800 ° F. and 20 ksi. About 2.3 times longer, or about 2.0 times to about 2.6 times longer creep life, and about 28% longer than the corresponding creep life exhibited by a corresponding article formed from R108, or about 25% It has a creep life that is about 31% longer.

  In one embodiment, an article formed from RNX according to the present disclosure exhibits an oxidation resistance substantially the same as the corresponding oxidation resistance exhibited by the corresponding article formed from N2Re, as well as the corresponding article formed from R108. It has an oxidation resistance that is about 3 times higher than the corresponding oxidation resistance, or about 2.7 times to about 3.3 times higher.

  In one embodiment, an article formed from RNX according to the present disclosure exhibits a hot corrosion resistance that is substantially the same as the corresponding hot corrosion resistance exhibited by the corresponding article formed from N2Re, as well as the corresponding article formed from R108. It has a high temperature corrosion resistance that is about 2 times higher than the corresponding high temperature corrosion resistance, or about 1.8 times to about 3.2 times higher.

  Referring to FIG. 4, a comparison of oxide depth between an article formed from RNX according to the present disclosure and a corresponding article formed from R108 under test conditions of 2000 ° F. up to 4000 hours in a burner rig. It is shown.

  Referring to FIGS. 5 and 6, in one embodiment, an article formed from RNX according to the present disclosure (FIG. 5) that has undergone a 2000 ° F. test over 4000 hours in a burner rig has a composition degradation depth 502. A corresponding article (FIG. 6) formed from R108 that includes and has an equiaxed crystal structure includes an R108 degradation depth 602. Articles formed from RNX experience surface degradation at a rate of about one half or about one quarter to about three quarters of the corresponding article formed from R108. As used herein, “degradation” means the disappearance of the cohesive reinforcing phase gamma prime (γ ′).

In another embodiment, the chemical formula of γ ′ is Ni ₃ (AlTiTa). Without being bound by theory, it is believed that the oxidation of Al and Ti destroys γ ′ and forms a degraded region. In the degraded region, the RNX contains a weakened matrix and significantly reduces load bearing capacity. A significant decrease in load bearing capacity can lead to premature failure when the article is exposed to operating conditions. Accordingly, the narrow degradation area of an article formed from RNX according to the present disclosure represents a significant improvement over the corresponding article formed from R108 when the article is a gas turbine or aircraft engine hot gas path component. ing.

  In articles formed from RNX, both the oxide layer depth and the corrosion depth are reduced compared to the corresponding articles formed from R108. Without being bound by theory, hafnium (Hf) is very reactive with oxygen and the high concentration of hafnium (Hf) in R108 compared to RNX (approximately three times higher) is the solidification of the article in the casting process. It promotes the separation of hafnium (Hf) therein, and severely corrodes articles formed from alloys (such as R108) that have a higher hafnium (Hf) concentration than RNX.

  Although the invention has been described with reference to one or more embodiments, various modifications can be made without departing from the scope of the invention, and elements of the invention may be replaced by equivalents. You will understand that it can be done. In addition, many modifications may be made to apply a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Accordingly, the present invention is not intended to be limited to the specific embodiments that are contemplated to practice the invention and disclosed as the best mode, but are intended to include all embodiments that fall within the scope of the appended claims. .

502 Degradation depth of composition 602 Degradation depth of R108

Claims (10)

An article comprising an equiaxed crystal structure and a composition, wherein the composition is in weight percent,
About 6.0% to about 9.0% aluminum (Al),
Titanium (Ti) about 0.5% or less,
Tantalum (Ta) about 2.5% to about 4.5%,
About 10.0% to about 12.5% chromium (Cr),
About 5.0% to about 10.0% cobalt (Co),
Molybdenum (Mo) about 0.30% to about 0.80%,
Tungsten (W) about 2.0% to about 5.0%,
Silicon (Si) about 1.0% or less,
Hafnium (Hf) about 0.35% to about 0.60%,
About 0.005% to about 0.010% of boron (B),
About 0.06% to about 0.10% carbon (C),
Zirconium (Zr) about 0.02% or less,
Lanthanum (La) about 0.1% or less,
Yttrium (Y) about 0.03% or less,
Contains the remaining nickel (Ni) and inevitable impurities,
Articles where rhenium (Re) is a trace element, if present.   The article of claim 1, wherein about 2.5% to about 4.5% of tantalum (Ta) is completely or partially replaced with niobium (Nb) on a 1: 1 molar basis.   The article of claim 1, wherein the composition is highly castable.   The article of claim 1, wherein the composition of the article has oxidation resistance and the oxidation resistance is about 2 to about 4 times higher than the corresponding oxidation resistance exhibited by the corresponding composition of R108.   The article of claim 1, wherein the composition of the article has a low cycle fatigue life, wherein the low cycle fatigue life is about 18% to about 22% longer than the corresponding low cycle fatigue life exhibited by the corresponding composition of N2Re. .   The article of claim 1, wherein the composition of the article has a creep life, and the creep life is about 2.0 to about 2.5 times longer than the corresponding creep life exhibited by the corresponding composition of N2Re.   2. The article of claim 1, wherein the composition of the article has high temperature corrosion resistance, and the high temperature corrosion resistance is about 1.5 to about 2.5 times longer than the corresponding high temperature corrosion resistance exhibited by the corresponding composition of R108. Goods. A method for manufacturing an article, comprising:
% By weight
About 6.0% to about 9.0% aluminum (Al),
Titanium (Ti) about 0.5% or less,
Tantalum (Ta) about 2.5% to about 4.5%,
About 10.0% to about 12.5% chromium (Cr),
About 5.0% to about 10.0% cobalt (Co),
Molybdenum (Mo) about 0.30% to about 0.80%,
Tungsten (W) about 2.0% to about 5.0%,
Silicon (Si) about 1.0% or less,
Hafnium (Hf) about 0.35% to about 0.60%,
About 0.005% to about 0.010% of boron (B),
About 0.06% to about 0.10% carbon (C),
Zirconium (Zr) about 0.02% or less,
Lanthanum (La) about 0.1% or less,
Yttrium (Y) about 0.03% or less,
Rhenium (Re) about 0.01% or less,
Preparing a composition comprising the remaining nickel (Ni) and inevitable impurities;
Forming an article comprising an equiaxed crystal structure;
Including a method.   The method of claim 8, wherein the casting comprises precision investment casting with variable pressure control. Precision investment casting with variable pressure control
A surface remelting pressure of 10 ⁻³ atm, and
The method according to claim 9, comprising an inert gas casting pressure of 10 ⁻² atmospheres to 10 ⁻¹ atmospheres.