EP1211336B1 - Nickel based superalloy for single crystal turbine blades of industrial turbines having a high resistance to hot corrosion - Google Patents
Nickel based superalloy for single crystal turbine blades of industrial turbines having a high resistance to hot corrosion Download PDFInfo
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- EP1211336B1 EP1211336B1 EP00403362A EP00403362A EP1211336B1 EP 1211336 B1 EP1211336 B1 EP 1211336B1 EP 00403362 A EP00403362 A EP 00403362A EP 00403362 A EP00403362 A EP 00403362A EP 1211336 B1 EP1211336 B1 EP 1211336B1
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C19/00—Alloys based on nickel or cobalt
- C22C19/03—Alloys based on nickel or cobalt based on nickel
- C22C19/05—Alloys based on nickel or cobalt based on nickel with chromium
- C22C19/051—Alloys based on nickel or cobalt based on nickel with chromium and Mo or W
- C22C19/056—Alloys based on nickel or cobalt based on nickel with chromium and Mo or W with the maximum Cr content being at least 10% but less than 20%
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- the invention relates to a nickel-based superalloy suitable for the controlled solidification production of stationary and mobile monocrystalline blades of industrial gas turbines.
- Nickel-based superalloys are the most efficient materials used today for the manufacture of stationary and mobile blades for industrial gas turbines. The two main features required so far for these alloys for these specific applications are good creep resistance at temperatures up to 850 ° C and very good resistance to hot corrosion. Reference alloys commonly used in this field are those known as IN738, IN939 and IN792.
- the blades made with these reference alloys are prepared by conventional lost-wax casting and have a polycrystalline structure, that is to say that they consist of the juxtaposition of randomly oriented crystals with respect to one another. and called grains. These grains are themselves constituted by a nickel-based austenitic gamma ( ⁇ ) matrix in which gamma prime ( ⁇ ') phase hardening particles whose base is the Ni 3 Al intermetallic compound are dispersed. These grains give these alloys high creep resistance up to temperatures close to 850 ° C., which guarantees the longevity of the blades for which life times of between 50 000 and 100 000 hours are generally sought.
- the chemical composition of the IN939, IN738 and IN792 alloys has been defined in order to give them an excellent resistance to the environment of the combustion gases, in particular with respect to hot corrosion, a particularly aggressive phenomenon in the case of gas turbines industrial.
- Important additions of chromium, typically between 12 and 22% by weight, are thus necessary to give these alloys the hot corrosion resistance required for the applications concerned.
- the classification of these alloys is: IN939 ⁇ IN738 ⁇ IN792. From the point of view of resistance to hot corrosion, the classification is reversed, ie: IN792 ⁇ IN738 ⁇ IN939.
- These monocrystalline blades are manufactured by solidification directed in lost-wax foundry.
- the elimination of grain boundaries, which are preferred locations for creep deformation at high temperatures, has dramatically increased the performance of nickel-based superalloys.
- the monocrystalline solidification process makes it possible to select the preferential orientation of growth of the monocrystalline part and thus to choose the ⁇ 001> orientation which is optimal from the point of view of resistance to creep and to thermal fatigue, these two mechanical stressing modes being the most harmful for turbine blades.
- the superalloy chemical compositions developed for monocrystalline turbine blades for aeronautical applications are not suitable for blades for terrestrial or marine applications, so-called industrial applications. These alloys are indeed defined so as to favor their mechanical strength up to temperatures above 1100 ° C, and this to the detriment of their resistance to hot corrosion.
- the chromium concentration of the superalloys for single-crystal blades of aeronautical turbines is generally less than 8% by weight, which makes it possible to reach ⁇ 'phase volume fractions of the order of 70%, favorable to resistance to high creep. temperature.
- a chromium-rich nickel-based superalloy capable of monocrystalline solidification of industrial gas turbine parts is known under the name SC16 and described in FR 2 643 085 A. Its chromium concentration is equal to 16% by weight.
- the creep resistance characteristics of the SC16 alloy are such that this alloy provides, relative to the reference polycrystalline alloy IN738, an operating temperature gain of approximately 30 ° C. (830 ° C. instead of 800 ° C.). at about 50 ° C (950 ° C instead of 900 ° C). Comparative tests for cyclic corrosion at 850 ° C in air at atmospheric pressure with Na 2 SO 4 contamination showed that the hot-corrosion resistance of the SC16 alloy was at least equivalent to that of the alloy polycrystalline reference IN738.
- the object of the invention is to provide a nickel-based superalloy having a resistance to hot corrosion, in the aggressive environment of the combustion gases of industrial gas turbines, at least equivalent to that of the reference polycristalline superalloy IN792 , with a creep resistance greater than or equal to that of the IN792 reference alloy in a temperature range of up to 1000 ° C.
- This superalloy must in particular be suitable for the production by directed solidification of fixed and mobile monocrystalline blades of large dimensions (up to several tens of centimeters in height) of industrial gas turbines.
- This superalloy must also show good microstructural stability with respect to the precipitation of chromium-rich brittle intermetallic phases during long-term high temperature holdings.
- the superalloy according to the invention capable of monocrystalline solidification, has the following weight composition: Co: 4.75 at 5.25% Cr: 11.5 at 12.5% MB: 0.8 at 1.2% W: 3.75 at 4.25% al: 3.75 at 4.25% Ti: 4 at 4.8% Your: 1.75 at 2.25% VS: 0.006 at 0.04% B: ⁇ 0.01% Zr: ⁇ 0.01% Hf: ⁇ 1% Nb: ⁇ 1% Ni and possible impurities: 100% complement.
- the alloy according to the invention has an excellent compromise between creep resistance and hot corrosion resistance. It is suitable for the manufacture of monocrystalline parts, that is to say made of a single metallurgical grain. This particular structure is obtained for example by means of a conventional method of solidification directed in a thermal gradient, using a helical or baffled grain selection device or a monocrystalline seed.
- the invention also relates to an industrial turbine blade made by monocrystalline solidification of the superalloy above.
- Figures 1 and 2 are graphs illustrating the properties of different superalloys.
- SCB444 An alloy according to the invention called SCB444 was developed with reference to the nominal composition shown in Table I. In this table are also reported the nominal concentrations of major elements of the reference alloys IN939, IN738, IN792 and SC16. Table I: Concentrations by weight in major elements (%) Alloy Or Co Cr MB W A1 Ti Your Nb IN939 Based 19 22.5 - 2 1.9 3.7 1.4 1 IN738 Based 8.5 16 1.7 2.6 3.4 3.4 1.7 0.9 IN792 Based 9 12.4 1.9 3.8 3.1 4.5 3.9 - SC16 Based - 16 3 - 3.5 3.5 3.5 - SCB444 Based 5 12 1 4 4 4.4 2 -
- Chromium has a beneficial and preponderant effect on the resistance to hot corrosion of nickel-based superalloys.
- the experiment thus showed that a concentration close to 12% by weight was necessary and sufficient in the alloy of the invention to obtain a resistance to hot corrosion equivalent to that of the reference alloy IN792 under the conditions hot corrosion tests described below, which are representative of the environment created by the combustion gases of certain industrial turbines.
- a higher chromium content would not make it possible to reach the volume fraction of the ⁇ 'phase necessary for the good creep resistance of the alloy up to 1000 ° C., without the alloy becoming unstable with respect to the precipitation of Fragile intermetallic phases rich in chromium in the ⁇ matrix.
- a lower concentration of chromium would not match the resistance to hot corrosion of the reference alloy IN792.
- Chromium also participates in the hardening of the ⁇ matrix in which this element is distributed preferentially.
- Molybdenum strongly hardens the matrix ⁇ in which this element is distributed preferentially.
- the amount of molybdenum that can be introduced into the alloy is however limited because this element has a detrimental effect on the hot corrosion resistance of nickel-based superalloys.
- a concentration close to 1% by weight in the alloy of the invention is not detrimental to its resistance to corrosion and significantly contributes to its hardening.
- Cobalt also participates in solid solution hardening of the ⁇ matrix.
- the cobalt concentration has an influence on the solution temperature of the hardening phase ⁇ '(solvus temperature ⁇ '). It is thus advantageous to increase the cobalt concentration to lower the solvus temperature of the ⁇ 'phase and to facilitate the homogenization of the alloy by heat treatment without risk of causing a start of melting. Moreover, it may also be advantageous to reduce the cobalt concentration in order to increase the solvus temperature of the ⁇ 'phase and thus to benefit from greater stability of the ⁇ ' phase at high temperature, which is favorable to the creep resistance.
- the concentration of 5% by weight of cobalt in the alloy of the invention leads to an optimal compromise between good homogenization ability and good creep resistance.
- the tungsten whose concentration is around 4% by weight in the alloy of the invention is distributed substantially equally between the ⁇ and ⁇ 'phases and thus contributes to their respective hardenings. His concentration in the alloy is however limited because this element is heavy, and has a negative effect on the resistance to hot corrosion.
- the concentration of aluminum is around 4% by weight in the alloy of the invention.
- the presence of this element causes the precipitation of the hardening phase ⁇ '.
- Aluminum also promotes resistance to oxidation.
- the titanium and tantalum elements are added to the alloy of the invention in order to reinforce the ⁇ 'phase in which they substitute for the aluminum element.
- the respective concentrations of these two elements in the alloy of the invention are close to 4.4% by weight for titanium and 2% by weight for tantalum. Under the conditions described below for hot corrosion tests, corresponding to the intended application, experience has shown that the presence of titanium is more favorable to the resistance to hot corrosion than that of tantalum. .
- the titanium concentration has however been limited on the one hand by the fact that this element can have a negative effect on the oxidation resistance, and on the other hand because a too high concentration of titanium can cause a destabilization of the ⁇ 'phase.
- the sum of the concentrations of tantalum, titanium and aluminum roughly defines the hardening phase volume fraction ⁇ '.
- the concentrations of these three elements have been adjusted in such a way as to optimize the ⁇ 'phase volume fraction, while keeping the stable ⁇ and ⁇ ' phases during the long-term hold at high temperature, and taking into account that the Chromium concentration was set at about 12% by weight so as to achieve the desired corrosion resistance.
- Alloy SCB444 was developed as ⁇ 001> orientation monocrystals. The density of this alloy was measured and found to be 8.22 g.cm -3 .
- the alloy After directed solidification, the alloy consists essentially of two phases: the austenitic matrix ⁇ , a nickel-based solid solution, and the ⁇ 'phase, an intermetallic compound whose basic formula is Ni 3 Al, which precipitates most of it within the ⁇ matrix in the form of fine particles smaller than one micrometer in the course of solid state cooling.
- ⁇ 'phase an intermetallic compound whose basic formula is Ni 3 Al, which precipitates most of it within the ⁇ matrix in the form of fine particles smaller than one micrometer in the course of solid state cooling.
- a small fraction of ⁇ 'phase is also found in massive particles resulting from a liquid eutectic transformation -> ⁇ + ⁇ ' at the end of solidification.
- the eutectic phase volume fraction ⁇ / ⁇ ' is close to 1.4%.
- the SCB444 alloy was subjected to a homogenization heat treatment at a temperature of 1270 ° C. for 3 hours with cooling in air. This temperature is greater than the solvus temperature of the ⁇ 'phase (solution dissolution temperature of the ⁇ ' phase precipitates), which is equal to 1253 ° C., and lower than the melting start temperature, equal to 1285 ° C. vs.
- This treatment aims to dissolve all the ⁇ 'phase precipitates whose size distribution is very extensive in the raw state of solidification directed, to eliminate massive particles of eutectic ⁇ / ⁇ ' and reduce heterogeneities related to the dendritic solidification structure.
- the cooling following the homogenization treatment described above was carried out by quenching in air.
- the speed of this cooling must be sufficiently high so that the size of the particles having precipitated during this cooling is less than 500 nm.
- the homogenization heat treatment procedure that has just been described is an example that makes it possible to obtain the desired result, ie a homogeneous distribution of fine ⁇ 'phase particles whose size does not exceed 500 nm.
- the SCB444 alloy was tested after being subjected to a homogenization treatment as described above, and then to two income treatments making it possible to stabilize the size and the volume fraction of the ⁇ 'phase precipitates.
- a first treatment of income was to heat the alloy at 1100 ° C for 4 hours with cooling in air which has the effect of stabilizing the size of ⁇ phase precipitates.
- a second treatment of income at 850 ° C for 24 hours, followed by cooling in air, optimizes the volume fraction of phase ⁇ '. This ⁇ 'phase volume fraction is estimated at 57% in the SCB444 alloy.
- the ⁇ 'phase precipitated in the form of cuboidal particles whose size is between 200 and 500 nm.
- Hot cyclic corrosion tests were carried out at 900 ° C on the SCB444 alloy in an industrial corrosion bench with burner.
- the cycle was as follows: 1 hour at 900 ° C in the corrosive atmosphere produced by the burner, then 15 minutes out of the oven at room temperature.
- the burner operated with 0.20% sulfur fuel.
- a saline solution at 0.5 gl -1 NaCl was vaporized on the sample at a rate of 2.2 m 3 ⁇ h -1 .
- the sample was coated every 100 hours with a deposition of 0.5 mg.cm -2 Na 2 SO 4 .
- alloys IN738 and IN792 were tested simultaneously.
- the corrosion resistance criterion is the number of cycles for which the first pits of corrosion appear on the surface of the sample.
- the graph in FIG. 2 makes it possible to compare the creep rupture times obtained for alloys SCB444, IN738, IN792 and SC16.
- On the abscissa is the applied stress.
- On the ordinate is the value of the Larson-Miller parameter.
- T is the creep temperature in Kelvin
- t the break time in hours.
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Description
L'invention concerne un superalliage à base de nickel, adapté à la fabrication par solidification dirigée d'aubes monocristallines fixes et mobiles de turbines à gaz industrielles.The invention relates to a nickel-based superalloy suitable for the controlled solidification production of stationary and mobile monocrystalline blades of industrial gas turbines.
Les superalliages à base de nickel sont les matériaux les plus performants utilisés aujourd'hui pour la fabrication des aubes fixes et mobiles des turbines à gaz industrielles. Les deux principales caractéristiques demandées jusqu'à maintenant à ces alliages pour ces applications spécifiques sont une bonne résistance au fluage à des températures pouvant aller jusqu'à 850 °C et une très bonne tenue à la corrosion à chaud. Des alliages de référence couramment utilisés dans ce domaine sont ceux connus sous les désignations IN738, IN939 et IN792.Nickel-based superalloys are the most efficient materials used today for the manufacture of stationary and mobile blades for industrial gas turbines. The two main features required so far for these alloys for these specific applications are good creep resistance at temperatures up to 850 ° C and very good resistance to hot corrosion. Reference alloys commonly used in this field are those known as IN738, IN939 and IN792.
Les aubes fabriquées avec ces alliages de référence sont élaborées par fonderie conventionnelle à la cire perdue et ont une structure polycristalline, c'est-à-dire qu'elles sont constituées de la juxtaposition de cristaux orientés de manière aléatoire les uns par rapport aux autres et appelés grains. Ces grains sont eux-mêmes constitués d'une matrice gamma (γ) austénitique à base de nickel dans laquelle sont dispersées des particules durcissantes de phase gamma prime (γ') dont la base est le composé intermétallique Ni3Al. Cette structure particulière des grains confère à ces alliages une résistance élevée en fluage jusqu'à des températures voisines de 850 °C, ce qui garantit la longévité des aubes pour lesquelles on recherche généralement des durées de vie comprises entre 50 000 et 100 000 heures. La composition chimique des alliages IN939, IN738 et IN792 a par ailleurs été définie de manière à leur conférer une excellente résistance à l'environnement des gaz de combustion, en particulier vis-à-vis de la corrosion à chaud, phénomène particulièrement agressif dans le cas des turbines à gaz industrielles. Des ajouts importants de chrome, typiquement entre 12 et 22 % en poids, sont ainsi nécessaires pour conférer à ces alliages la tenue à la corrosion à chaud requise pour les applications concernées. Du point de vue de la résistance au fluage le classement de ces alliages est: IN939 < IN738 < IN792. Du point de vue de la résistance à la corrosion à chaud, le classement est inversé, soit: IN792 < IN738 < IN939.The blades made with these reference alloys are prepared by conventional lost-wax casting and have a polycrystalline structure, that is to say that they consist of the juxtaposition of randomly oriented crystals with respect to one another. and called grains. These grains are themselves constituted by a nickel-based austenitic gamma (γ) matrix in which gamma prime (γ ') phase hardening particles whose base is the Ni 3 Al intermetallic compound are dispersed. These grains give these alloys high creep resistance up to temperatures close to 850 ° C., which guarantees the longevity of the blades for which life times of between 50 000 and 100 000 hours are generally sought. The chemical composition of the IN939, IN738 and IN792 alloys has been defined in order to give them an excellent resistance to the environment of the combustion gases, in particular with respect to hot corrosion, a particularly aggressive phenomenon in the case of gas turbines industrial. Important additions of chromium, typically between 12 and 22% by weight, are thus necessary to give these alloys the hot corrosion resistance required for the applications concerned. From the point of view of creep resistance the classification of these alloys is: IN939 <IN738 <IN792. From the point of view of resistance to hot corrosion, the classification is reversed, ie: IN792 <IN738 <IN939.
Pour améliorer les performances des turbines à gaz industrielles, en termes de rendement et de consommation, une voie consiste à augmenter la température des gaz à l'entrée de la turbine. Ceci nécessite par conséquent de pouvoir disposer d'alliages pour aubes de turbines pouvant supporter des températures de fonctionnement de plus en plus élevées, tout en conservant les mêmes caractéristiques mécaniques, en particulier en fluage, afin de pouvoir atteindre les mêmes durées de vie.To improve the performance of industrial gas turbines, in terms of efficiency and consumption, one way is to increase the temperature of the gases at the inlet of the turbine. This therefore requires the availability of alloys for turbine blades that can withstand increasingly higher operating temperatures, while maintaining the same mechanical characteristics, particularly creep, in order to achieve the same lifetimes.
Le même type de problème s'est posé par le passé dans le cas des turbines à gaz de turboréacteurs et de turbomachines pour applications aéronautiques. Dans ce cas la solution retenue a consisté à passer des aubes dites polycristallines élaborées par fonderie conventionnelle aux aubes dites monocristallines, c'est-à-dire constituées d'un seul grain métallurgique.The same type of problem has arisen in the past in the case of gas turbines for turbojets and turbomachines for aeronautical applications. In this case the solution adopted was to pass so-called polycrystalline blades developed by conventional foundry so-called monocrystalline blades, that is to say consist of a single metallurgical grain.
Ces aubes monocristallines sont fabriquées par solidification dirigée en fonderie à la cire perdue. L'élimination des joints de grains, qui sont des lieux préférentiels de déformation en fluage à haute température, a permis d'augmenter de manière spectaculaire les performances des superalliages à base de nickel. De plus le procédé de solidification monocristalline permet de sélectionner l'orientation préférentielle de croissance de la pièce monocristalline et de choisir ainsi l'orientation <001> qui est optimale du point de vue de la résistance au fluage et à la fatigue thermique, ces deux modes de sollicitation mécanique étant les plus nocifs pour les aubes de turbines.These monocrystalline blades are manufactured by solidification directed in lost-wax foundry. The elimination of grain boundaries, which are preferred locations for creep deformation at high temperatures, has dramatically increased the performance of nickel-based superalloys. In addition, the monocrystalline solidification process makes it possible to select the preferential orientation of growth of the monocrystalline part and thus to choose the <001> orientation which is optimal from the point of view of resistance to creep and to thermal fatigue, these two mechanical stressing modes being the most harmful for turbine blades.
Cependant les compositions chimiques de superalliages développées pour les aubes monocristallines de turbines pour applications aéronautiques ne conviennent pas pour les aubes pour applications terrestres ou marines, dites industrielles. Ces alliages sont en effet définis de manière à privilégier leur résistance mécanique jusqu'à des températures supérieures à 1100 °C, et ce au détriment de leur résistance à la corrosion à chaud. Ainsi la concentration en chrome des superalliages pour aubes monocristallines de turbines aéronautiques est généralement inférieure à 8 % en poids ce qui permet d'atteindre des fractions volumiques de phase γ' de l'ordre de 70 %, favorables à la résistance au fluage à haute température.However, the superalloy chemical compositions developed for monocrystalline turbine blades for aeronautical applications are not suitable for blades for terrestrial or marine applications, so-called industrial applications. These alloys are indeed defined so as to favor their mechanical strength up to temperatures above 1100 ° C, and this to the detriment of their resistance to hot corrosion. Thus, the chromium concentration of the superalloys for single-crystal blades of aeronautical turbines is generally less than 8% by weight, which makes it possible to reach γ 'phase volume fractions of the order of 70%, favorable to resistance to high creep. temperature.
Un superalliage à base de nickel riche en chrome et apte à la solidification monocristalline de pièces de turbines à gaz industrielles est connu sous la dénomination SC16 et décrit dans FR 2 643 085 A. Sa concentration en chrome est égale à 16 % en poids. Les caractéristiques de résistance au fluage de l'alliage SC16 sont telles que cet alliage apporte par rapport à l'alliage polycristallin de référence IN738 un gain en température de fonctionnement allant de 30 °C environ (830 °C au lieu de 800 °C) à 50 °C environ (950 °C au lieu de 900 °C). Des essais comparatifs de corrosion cyclique à 850 °C dans l'air à la pression atmosphérique avec contamination par Na2SO4 ont montré que la résistance à la corrosion à chaud de l'alliage SC16 était au moins équivalente à celle de l'alliage polycristallin de référence IN738.A chromium-rich nickel-based superalloy capable of monocrystalline solidification of industrial gas turbine parts is known under the name SC16 and described in FR 2 643 085 A. Its chromium concentration is equal to 16% by weight. The creep resistance characteristics of the SC16 alloy are such that this alloy provides, relative to the reference polycrystalline alloy IN738, an operating temperature gain of approximately 30 ° C. (830 ° C. instead of 800 ° C.). at about 50 ° C (950 ° C instead of 900 ° C). Comparative tests for cyclic corrosion at 850 ° C in air at atmospheric pressure with Na 2 SO 4 contamination showed that the hot-corrosion resistance of the SC16 alloy was at least equivalent to that of the alloy polycrystalline reference IN738.
Des essais de corrosion à chaud ont été réalisés sur l'alliage SC16 par les fabricants de turbines industrielles dans leurs propres bancs d'essai. Dans des environnements très sévères, représentatifs de conditions extrêmes de fonctionnement, il a été montré que la résistance à la corrosion à chaud de cet alliage restait inférieure à celle de l'alliage IN738.Hot corrosion tests were conducted on the SC16 alloy by industrial turbine manufacturers in their own test benches. In very severe environments, representative of extreme operating conditions, it has been shown that the resistance to hot corrosion of this alloy remains lower than that of the IN738 alloy.
Par ailleurs, la demande croissante de ces fabricants pour une augmentation de la température de fonctionnement des turbines à gaz nécessite une résistance au fluage encore améliorée des superalliages pour aubes.Moreover, the increasing demand of these manufacturers for an increase in the operating temperature of Gas turbines require even better creep resistance of blade superalloys.
Le but de l'invention est de proposer un superalliage à base de nickel présentant une résistance à la corrosion à chaud, dans l'environnement agressif des gaz de combustion des turbines à gaz industrielles, au moins équivalente à celle du superalliage polycristallin de référence IN792, avec une résistance au fluage supérieure ou égale à celle de l'alliage de référence IN792 dans une gamme de températures allant jusqu'à 1000 °C.The object of the invention is to provide a nickel-based superalloy having a resistance to hot corrosion, in the aggressive environment of the combustion gases of industrial gas turbines, at least equivalent to that of the reference polycristalline superalloy IN792 , with a creep resistance greater than or equal to that of the IN792 reference alloy in a temperature range of up to 1000 ° C.
Ce superalliage doit en particulier convenir à la fabrication par solidification dirigée d'aubes monocristallines fixes et mobiles de grandes dimensions (jusqu'à plusieurs dizaines de centimètres de hauteur) de turbines à gaz industrielles.This superalloy must in particular be suitable for the production by directed solidification of fixed and mobile monocrystalline blades of large dimensions (up to several tens of centimeters in height) of industrial gas turbines.
Ce superalliage doit de plus montrer une bonne stabilité microstructurale vis-à-vis de la précipitation de phases intermétalliques fragiles riches en chrome au cours de maintiens de longue durée à haute température.This superalloy must also show good microstructural stability with respect to the precipitation of chromium-rich brittle intermetallic phases during long-term high temperature holdings.
Plus spécifiquement, on a recherché une composition d'alliage assurant:
- Une résistance à la corrosion à chaud optimisée, dans tous les cas au moins égale à celle du superalliage polycristallin de référence IN792, et ce dans divers environnements représentatifs de celui des gaz de combustion des turbines industrielles;
- Une fraction volumique maximale de précipités durcissants de phase γ' afin de favoriser la résistance au fluage à haute température;
- Une résistance au fluage jusqu'à 1000 °C supérieure à celle de l'alliage polycristallin de référence IN792;
- Une aptitude à l'homogénéisation par remise en solution totale des particules de phase γ', y compris les phases eutectiques γ/γ';
- L'absence de précipitation de phases intermétalliques fragiles riches en chrome, à partir de la matrice γ, au cours de maintiens de longue durée à haute température;
- Une masse volumique inférieure à 8,4 g.cm-3 afin de minimiser la masse des aubes monocristallines et par conséquent de limiter la contrainte centrifuge agissant sur ces aubes et sur le disque de turbine sur lequel elles sont fixées;
- Une bonne aptitude à la solidification monocristalline d'aubes de turbines dont la hauteur peut atteindre plusieurs dizaines de centimètres et la masse plusieurs kilogrammes.
- Optimized hot-corrosion resistance, in all cases at least equal to that of the reference polycristalline superalloy IN792, and this in various environments representative of that of the combustion gases of industrial turbines;
- A maximum volume fraction of γ 'phase hardening precipitates to promote creep resistance at high temperature;
- Creep resistance up to 1000 ° C higher than that of the reference polycrystalline alloy IN792;
- An ability to homogenize by total dissolution of the γ 'phase particles, including the eutectic phases γ / γ';
- The absence of precipitation of chromium-rich brittle intermetallic phases, from the γ matrix, during long-term high temperature maintenance;
- A density of less than 8.4 gcm -3 in order to minimize the mass of the single-crystal blades and consequently to limit the centrifugal stress acting on these vanes and on the turbine disc on which they are fixed;
- Good ability to monocrystalline solidification of turbine blades whose height can reach several tens of centimeters and the mass several kilograms.
Le superalliage selon l'invention, apte à la solidification monocristalline, possède la composition pondérale suivante:
L'alliage selon l'invention présente un excellent compromis entre la résistance au fluage et la résistance à la corrosion à chaud. Il convient à la fabrication de pièces monocristallines, c'est-à-dire constituées d'un seul grain métallurgique. Cette structure particulière est obtenue par exemple à l'aide d'un procédé classique de solidification dirigée dans un gradient thermique, en utilisant un dispositif de sélection de grain à hélice ou à chicanes ou un germe monocristallin.The alloy according to the invention has an excellent compromise between creep resistance and hot corrosion resistance. It is suitable for the manufacture of monocrystalline parts, that is to say made of a single metallurgical grain. This particular structure is obtained for example by means of a conventional method of solidification directed in a thermal gradient, using a helical or baffled grain selection device or a monocrystalline seed.
L'invention a également pour objet une aube de turbine industrielle réalisée par solidification monocristalline du superalliage ci-dessus.The invention also relates to an industrial turbine blade made by monocrystalline solidification of the superalloy above.
Les caractéristiques et avantages de l'invention seront exposés plus en détail dans la description ci-après, en se référant aux dessins annexés.The features and advantages of the invention will be set forth in more detail in the description below, with reference to the accompanying drawings.
Les figures 1 et 2 sont des graphiques illustrant les propriétés de différents superalliages.Figures 1 and 2 are graphs illustrating the properties of different superalloys.
Un alliage selon l'invention dénommé SCB444 a été élaboré en visant la composition nominale présentée dans le tableau I. Dans ce tableau sont également reportées les concentrations nominales en éléments majeurs des alliages de référence IN939, IN738, IN792 et SC16.
Le chrome a un effet bénéfique et prépondérant sur la tenue à la corrosion à chaud des superalliages à base de nickel. L'expérience a ainsi montré qu'une concentration voisine de 12 % en poids était nécessaire et suffisante dans l'alliage de l'invention pour obtenir une résistance à la corrosion à chaud équivalente à celle de l'alliage de référence IN792 dans les conditions des essais de corrosion à chaud décrits plus loin, qui sont représentatives de l'environnement créé par les gaz de combustion de certaines turbines industrielles. Une teneur plus élevée en chrome ne permettrait pas d'atteindre la fraction volumique de phase γ' nécessaire à la bonne tenue en fluage de l'alliage jusqu'à 1000 °C, sans que l'alliage devienne instable vis-à-vis de la précipitation de phases intermétallique fragiles riches en chrome dans la matrice γ. Par ailleurs, une concentration plus faible en chrome ne permettrait pas d'égaler la résistance à la corrosion à chaud de l'alliage de référence IN792. Le chrome participe également au durcissement de la matrice γ dans laquelle cet élément se répartit préférentiellement.Chromium has a beneficial and preponderant effect on the resistance to hot corrosion of nickel-based superalloys. The experiment thus showed that a concentration close to 12% by weight was necessary and sufficient in the alloy of the invention to obtain a resistance to hot corrosion equivalent to that of the reference alloy IN792 under the conditions hot corrosion tests described below, which are representative of the environment created by the combustion gases of certain industrial turbines. A higher chromium content would not make it possible to reach the volume fraction of the γ 'phase necessary for the good creep resistance of the alloy up to 1000 ° C., without the alloy becoming unstable with respect to the precipitation of Fragile intermetallic phases rich in chromium in the γ matrix. In addition, a lower concentration of chromium would not match the resistance to hot corrosion of the reference alloy IN792. Chromium also participates in the hardening of the γ matrix in which this element is distributed preferentially.
Le molybdène durcit fortement la matrice γ dans laquelle cet élément se répartit préférentiellement. La quantité de molybdène pouvant être introduite dans l'alliage est cependant limitée car cet élément a un effet néfaste sur la résistance à la corrosion à chaud des superalliages à base de nickel. Une concentration voisine de 1 % en poids dans l'alliage de l'invention n'est pas pénalisante pour sa résistance à la corrosion et participe de manière significative à son durcissement.Molybdenum strongly hardens the matrix γ in which this element is distributed preferentially. The amount of molybdenum that can be introduced into the alloy is however limited because this element has a detrimental effect on the hot corrosion resistance of nickel-based superalloys. A concentration close to 1% by weight in the alloy of the invention is not detrimental to its resistance to corrosion and significantly contributes to its hardening.
Le cobalt participe également au durcissement en solution solide de la matrice γ. La concentration en cobalt a une influence sur la température de mise en solution de la phase durcissante γ' (température de solvus γ'). Il est ainsi avantageux d'augmenter la concentration en cobalt pour abaisser la température de solvus de la phase γ' et faciliter l'homogénéisation de l'alliage par traitement thermique sans risque de provoquer un début de fusion. Par ailleurs il peut être également avantageux de réduire la concentration en cobalt afin d'augmenter la température de solvus de la phase γ' et de bénéficier ainsi d'une plus grande stabilité de la phase γ' à haute température ce qui est favorable à la résistance au fluage. La concentration voisine de 5 % en poids de cobalt dans l'alliage de l'invention conduit à un compromis optimal entre une bonne aptitude à l'homogénéisation et une bonne tenue au fluage.Cobalt also participates in solid solution hardening of the γ matrix. The cobalt concentration has an influence on the solution temperature of the hardening phase γ '(solvus temperature γ'). It is thus advantageous to increase the cobalt concentration to lower the solvus temperature of the γ 'phase and to facilitate the homogenization of the alloy by heat treatment without risk of causing a start of melting. Moreover, it may also be advantageous to reduce the cobalt concentration in order to increase the solvus temperature of the γ 'phase and thus to benefit from greater stability of the γ' phase at high temperature, which is favorable to the creep resistance. The concentration of 5% by weight of cobalt in the alloy of the invention leads to an optimal compromise between good homogenization ability and good creep resistance.
Le tungstène dont la concentration est voisine de 4 % en poids dans l'alliage de l'invention se répartit de manière sensiblement égale entre les phases γ et γ' et contribue ainsi à leurs durcissements respectifs. Sa concentration dans l'alliage est cependant limitée car cet élément est lourd, et a un effet négatif sur la résistance à la corrosion à chaud.The tungsten whose concentration is around 4% by weight in the alloy of the invention is distributed substantially equally between the γ and γ 'phases and thus contributes to their respective hardenings. His concentration in the alloy is however limited because this element is heavy, and has a negative effect on the resistance to hot corrosion.
La concentration en aluminium est voisine de 4 % en poids dans l'alliage de l'invention. La présence de cet élément provoque la précipitation de la phase durcissante γ'. L'aluminium favorise également la résistance à l'oxydation. Les éléments titane et tantale sont ajoutés à l'alliage de l'invention afin de renforcer la phase γ' dans laquelle ils se substituent à l'élément aluminium. Les concentrations respectives de ces deux éléments dans l'alliage de l'invention sont voisines de 4,4 % en poids pour le titane et de 2 % en poids pour le tantale. Dans les conditions décrites plus loin d'essais de corrosion à chaud, correspondant à l'application visée, l'expérience a montré que la présence de titane était plus favorable à la résistance à la corrosion à chaud que ne l'est celle du tantale. La concentration en titane a cependant été limitée d'une part par le fait que cet élément peut avoir un effet négatif sur la tenue à l'oxydation, et d'autre part parce qu'une concentration trop élevée en titane peut entraîner une déstabilisation de la phase γ'. La somme des concentrations en tantale, titane et aluminium définit grossièrement la fraction volumique de phase durcissante γ'. Les concentrations de ces trois éléments ont été réglées de manière à optimiser la fraction volumique de phase γ', tout en conservant les phases γ et γ' stables au cours des maintiens de longue durée à haute température, et en tenant compte du fait que la concentration en chrome a été fixée à environ 12 % en poids de façon à atteindre la résistance à la corrosion désirée.The concentration of aluminum is around 4% by weight in the alloy of the invention. The presence of this element causes the precipitation of the hardening phase γ '. Aluminum also promotes resistance to oxidation. The titanium and tantalum elements are added to the alloy of the invention in order to reinforce the γ 'phase in which they substitute for the aluminum element. The respective concentrations of these two elements in the alloy of the invention are close to 4.4% by weight for titanium and 2% by weight for tantalum. Under the conditions described below for hot corrosion tests, corresponding to the intended application, experience has shown that the presence of titanium is more favorable to the resistance to hot corrosion than that of tantalum. . The titanium concentration has however been limited on the one hand by the fact that this element can have a negative effect on the oxidation resistance, and on the other hand because a too high concentration of titanium can cause a destabilization of the γ 'phase. The sum of the concentrations of tantalum, titanium and aluminum roughly defines the hardening phase volume fraction γ '. The concentrations of these three elements have been adjusted in such a way as to optimize the γ 'phase volume fraction, while keeping the stable γ and γ' phases during the long-term hold at high temperature, and taking into account that the Chromium concentration was set at about 12% by weight so as to achieve the desired corrosion resistance.
L'alliage SCB444 a été élaboré sous la forme de monocristaux d'orientation <001>. La masse volumique de cet alliage a été mesurée et trouvée égale à 8,22 g.cm-3.Alloy SCB444 was developed as <001> orientation monocrystals. The density of this alloy was measured and found to be 8.22 g.cm -3 .
Après solidification dirigée, l'alliage est essentiellement constitué de deux phases: la matrice austénitique γ, solution solide à base de nickel, et la phase γ', composé intermétallique dont la formule de base est Ni3Al, qui précipite en majeure partie au sein de la matrice γ sous la forme de fines particules de taille inférieure à un micromètre au cours du refroidissement à l'état solide. Une faible fraction de phase γ' se retrouve également dans des particules massives résultant d'une transformation eutectique liquide -> γ + γ' en fin de solidification. La fraction volumique de phase eutectique γ/γ' est voisine de 1,4 %.After directed solidification, the alloy consists essentially of two phases: the austenitic matrix γ, a nickel-based solid solution, and the γ 'phase, an intermetallic compound whose basic formula is Ni 3 Al, which precipitates most of it within the γ matrix in the form of fine particles smaller than one micrometer in the course of solid state cooling. A small fraction of γ 'phase is also found in massive particles resulting from a liquid eutectic transformation -> γ + γ' at the end of solidification. The eutectic phase volume fraction γ / γ 'is close to 1.4%.
L'alliage SCB444 a subi un traitement thermique d'homogénéisation à la température de 1270 °C pendant 3 heures avec refroidissement à l'air. Cette température est supérieure à la température de solvus de la phase γ' (température de mise en solution des précipités de phase γ'), qui est égale à 1253 °C, et inférieure à la température de début de fusion, égale à 1285 °C. Ce traitement a pour objectif de dissoudre la totalité des précipités de phase γ' dont la distribution de tailles est très étendue dans l'état brut de solidification dirigée, d'éliminer les particules massives d'eutectique γ/γ' et de réduire les hétérogénéités chimiques liées à la structure dendritique de solidification.The SCB444 alloy was subjected to a homogenization heat treatment at a temperature of 1270 ° C. for 3 hours with cooling in air. This temperature is greater than the solvus temperature of the γ 'phase (solution dissolution temperature of the γ' phase precipitates), which is equal to 1253 ° C., and lower than the melting start temperature, equal to 1285 ° C. vs. This treatment aims to dissolve all the γ 'phase precipitates whose size distribution is very extensive in the raw state of solidification directed, to eliminate massive particles of eutectic γ / γ' and reduce heterogeneities related to the dendritic solidification structure.
L'écart entre la température de solvus γ' de l'alliage SCB444 et sa température de début de fusion est très grand, ce qui autorise l'application aisée du traitement d'homogénéisation sans risque de fusion et avec la certitude d'obtenir une microstructure homogène autorisant une résistance au fluage optimisée.The difference between the SCB444 alloy 's solvate temperature γ' and its melting start temperature is very large, which allows the easy application of the homogenization treatment without the risk of melting and with the certainty of obtaining a homogeneous microstructure allowing optimized creep resistance.
Le refroidissement succédant au traitement d'homogénéisation décrit ci-dessus a été réalisé par trempe à l'air. En pratique, la vitesse de ce refroidissement doit être suffisamment élevée pour que la taille des particules ayant précipité au cours de ce refroidissement soit inférieure à 500 nm.The cooling following the homogenization treatment described above was carried out by quenching in air. In practice, the speed of this cooling must be sufficiently high so that the size of the particles having precipitated during this cooling is less than 500 nm.
La procédure de traitement thermique d'homogénéisation qui vient d'être décrite est un exemple permettant d'obtenir le résultat escompté, soit une distribution homogène de fines particules de phase γ' dont la taille n'excède pas 500 nm.The homogenization heat treatment procedure that has just been described is an example that makes it possible to obtain the desired result, ie a homogeneous distribution of fine γ 'phase particles whose size does not exceed 500 nm.
Ceci n'exclut pas la possibilité d'obtenir un résultat semblable en utilisant une autre température de traitement pourvu qu'elle soit comprise dans l'intervalle séparant la température de solvus γ' et la température de début de fusion.This does not exclude the possibility of obtaining a similar result by using another processing temperature provided that it is in the range separating the solvate temperature γ 'and the melting start temperature.
L'alliage SCB444 a été testé après avoir été soumis à un traitement d'homogénéisation tel que décrit plus haut, puis à deux traitements de revenu permettant de stabiliser la taille et la fraction volumique des précipités de phase γ'. Un premier traitement de revenu a consisté à chauffer l'alliage à 1100 °C pendant 4 heures avec refroidissement à l'air ce qui a pour effet de stabiliser la taille des précipités de phase γ'. Un deuxième traitement de revenu à 850 °C pendant 24 heures, suivi d'un refroidissement à l'air, permet d'optimiser la fraction volumique de phase γ'. Cette fraction volumique de phase γ' est estimée à 57 % dans l'alliage SCB444. À l'issue de l'ensemble des traitements thermiques, la phase γ' a précipité sous la forme de particules cuboïdales dont la taille est comprise entre 200 et 500 nm.The SCB444 alloy was tested after being subjected to a homogenization treatment as described above, and then to two income treatments making it possible to stabilize the size and the volume fraction of the γ 'phase precipitates. A first treatment of income was to heat the alloy at 1100 ° C for 4 hours with cooling in air which has the effect of stabilizing the size of γ phase precipitates. A second treatment of income at 850 ° C for 24 hours, followed by cooling in air, optimizes the volume fraction of phase γ '. This γ 'phase volume fraction is estimated at 57% in the SCB444 alloy. At the end of all the heat treatments, the γ 'phase precipitated in the form of cuboidal particles whose size is between 200 and 500 nm.
Des essais de corrosion cyclique à chaud ont été réalisés à 900 °C sur l'alliage SCB444 dans un banc de corrosion industriel avec brûleur. Le cycle était le suivant: 1 heure à 900 °C dans l'atmosphère corrosive produite par le brûleur, puis 15 minutes hors du four à la température ambiante. Le brûleur fonctionnait avec du fuel chargé de 0,20 % de soufre. Une solution d'eau salée à 0,5 g.l-1 de NaCl était vaporisée sur l'échantillon à un débit de 2,2 m3.h-1. L'échantillon était recouvert toutes les 100 heures d'un dépôt de 0,5 mg.cm-2 de Na2SO4. Pour comparaison, les alliages IN738 et IN792 ont été testés simultanément. Le critère de résistance à la corrosion est le nombre de cycles pour lequel les premières piqûres de corrosion apparaissent à la surface de l'échantillon.Hot cyclic corrosion tests were carried out at 900 ° C on the SCB444 alloy in an industrial corrosion bench with burner. The cycle was as follows: 1 hour at 900 ° C in the corrosive atmosphere produced by the burner, then 15 minutes out of the oven at room temperature. The burner operated with 0.20% sulfur fuel. A saline solution at 0.5 gl -1 NaCl was vaporized on the sample at a rate of 2.2 m 3 · h -1 . The sample was coated every 100 hours with a deposition of 0.5 mg.cm -2 Na 2 SO 4 . For comparison, alloys IN738 and IN792 were tested simultaneously. The corrosion resistance criterion is the number of cycles for which the first pits of corrosion appear on the surface of the sample.
Les résultats des essais de corrosion sont illustrés par le graphique de la figure 1. L'amorçage de la corrosion à 900 °C intervient pour des nombres de cycles comparables pour les alliages SCB444 et IN792 ce qui satisfait à l'objectif fixé.The results of the corrosion tests are illustrated by the graph in Figure 1. The initiation of corrosion at 900 ° C is used for comparable numbers of cycles for the SCB444 and IN792 alloys, which satisfies the set objective.
Des essais de fluage en traction ont été réalisés sur des éprouvettes usinées dans des barreaux monocristallins d'orientation <001>. Les barreaux ont été préalablement homogénéisés puis revenus selon les procédures décrites auparavant. Des valeurs de temps à rupture obtenues à 750, 850 et 950 °C pour différents niveaux de contrainte appliquée sont reportées dans le tableau II.
Le graphique de la figure 2 permet de comparer les temps à rupture en fluage obtenus pour les alliages SCB444, IN738, IN792 et SC16. En abscisse est portée la contrainte appliquée. En ordonnée est portée la valeur du paramètre de Larson-Miller. Ce paramètre est donné par la formule P = T(20 + log t) × 10-3 où T est la température de fluage en Kelvin et t le temps à rupture en heures. Ce graphique fait apparaître que la résistance au fluage de l'alliage SCB444 est nettement supérieure à celle de l'alliage IN792.The graph in FIG. 2 makes it possible to compare the creep rupture times obtained for alloys SCB444, IN738, IN792 and SC16. On the abscissa is the applied stress. On the ordinate is the value of the Larson-Miller parameter. This parameter is given by the formula P = T (20 + log t) × 10 -3 where T is the creep temperature in Kelvin and t is the break time in hours. This graph shows that the creep resistance of the SCB444 alloy is significantly higher than that of the IN792 alloy.
Le contrôle de la microstructure des éprouvettes d'alliage SCB444 à l'issue des essais de fluage a démontré l'absence de précipitation de particules intermétalliques fragiles riches en chrome susceptibles d'apparaître au cours de maintiens de longue durée à haute température dans les superalliages à base de nickel où la matrice γ est sursaturée en éléments d'addition.Control of microstructure of SCB444 alloy specimens after creep tests demonstrated the absence of precipitation of rich brittle intermetallic particles in chromium likely to occur during long-term high temperature maintenance in nickel-based superalloys where the matrix γ is supersaturated in addition elements.
Des essais de fabrication de pièces monocristallines en superalliage SCB444 ont montré qu'il était possible de couler un large éventail de composants dont la masse peut aller de quelques grammes à plus de 10 kg, avec divers degrés de complexité. La croissance des pièces selon l'orientation cristallographique <001> est favorisée et dominante et la présence de grains orientés de manière aléatoire est minimisée. Le métal liquide est stable en ce sens qu'il ne réagit pas avec les matériaux utilisés communément pour la fabrication des moules. Le phénomène de recristallisation pouvant se produire durant le traitement d'homogénéisation à haute température est absent dans le cas de l'alliage SCB444.Manufacturing trials of SCB444 superalloy monocrystalline parts have shown that it is possible to cast a wide range of components ranging in weight from a few grams to over 10 kg with varying degrees of complexity. Particle growth in the <001> crystallographic orientation is favored and dominant and the presence of randomly oriented grains is minimized. The liquid metal is stable in that it does not react with materials commonly used for mold making. The recrystallization phenomenon that can occur during the high temperature homogenization treatment is absent in the case of SCB444 alloy.
Claims (2)
- A nickel-based superalloy, suitable for single crystal solidification, characterized in that its composition by weight is as follows:
Co: 4.75 to 5.25 % Cr: 11.5 to 12.5 % Mo: 0.8 to 1.2 % W: 3.75 to 4.25 % Al: 3.75 to 4.25 % Ti: 4 to 4.8 % Ta: 1.75 to 2.25 % C: 0.006 to 0.04 % B: ≤ 0.01 % Zr: ≤ 0.01 % Hf: ≤ 1 % Nb: ≤ 1 % Ni and possible impurities: to 100 %. - An industrial turbine blade produced by single crystal solidification of a superalloy according to claim 1.
Priority Applications (5)
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DE60035052T DE60035052T2 (en) | 2000-11-30 | 2000-11-30 | Nickel base superalloy for single crystal turbine blades of industrial turbines with high resistance to hot corrosion |
EP00403362A EP1211336B1 (en) | 2000-11-30 | 2000-11-30 | Nickel based superalloy for single crystal turbine blades of industrial turbines having a high resistance to hot corrosion |
US10/008,745 US20030047252A1 (en) | 2000-11-30 | 2001-11-30 | Nickel-based superalloy having high resistance to hot-corrosion for monocrystalline blades of industrial turbines |
JP2001365810A JP2002194467A (en) | 2000-11-30 | 2001-11-30 | Nickel based superalloy having high temperature corrosion resistance for single crystal blade of industrial turbine |
US10/636,024 US20040069380A1 (en) | 2000-11-30 | 2003-08-07 | Nickel-based superalloy having high resistance to hot-corrosion for monocrystalline blades of industrial turbines |
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EP00403362A EP1211336B1 (en) | 2000-11-30 | 2000-11-30 | Nickel based superalloy for single crystal turbine blades of industrial turbines having a high resistance to hot corrosion |
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EP1211336B1 true EP1211336B1 (en) | 2007-05-30 |
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EP (1) | EP1211336B1 (en) |
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US20060182649A1 (en) * | 2005-02-16 | 2006-08-17 | Siemens Westinghouse Power Corp. | High strength oxidation resistant superalloy with enhanced coating compatibility |
EP2103700A1 (en) | 2008-03-14 | 2009-09-23 | Siemens Aktiengesellschaft | Nickel base alloy and use of it, turbine blade or vane and gas turbine |
FR3057880B1 (en) * | 2016-10-25 | 2018-11-23 | Safran | SUPERALLIAGE BASED ON NICKEL, MONOCRYSTALLINE AUBE AND TURBOMACHINE |
FR3097879B1 (en) * | 2019-06-28 | 2021-05-28 | Safran Aircraft Engines | PROCESS FOR MANUFACTURING A PART IN MONOCRISTALLINE SUPERALLY |
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DE3109293C2 (en) * | 1980-03-13 | 1985-08-01 | Rolls-Royce Ltd., London | Use of a nickel alloy for single crystal castings |
US5399313A (en) * | 1981-10-02 | 1995-03-21 | General Electric Company | Nickel-based superalloys for producing single crystal articles having improved tolerance to low angle grain boundaries |
US5154884A (en) * | 1981-10-02 | 1992-10-13 | General Electric Company | Single crystal nickel-base superalloy article and method for making |
US4885216A (en) * | 1987-04-03 | 1989-12-05 | Avco Corporation | High strength nickel base single crystal alloys |
GB2234521B (en) * | 1986-03-27 | 1991-05-01 | Gen Electric | Nickel-base superalloys for producing single crystal articles having improved tolerance to low angle grain boundaries |
US5403546A (en) * | 1989-02-10 | 1995-04-04 | Office National D'etudes Et De Recherches/Aerospatiales | Nickel-based superalloy for industrial turbine blades |
US5395584A (en) * | 1992-06-17 | 1995-03-07 | Avco Corporation | Nickel-base superalloy compositions |
US6355117B1 (en) * | 1992-10-30 | 2002-03-12 | United Technologies Corporation | Nickel base superalloy single crystal articles with improved performance in air and hydrogen |
JPH07286503A (en) * | 1994-04-20 | 1995-10-31 | Hitachi Ltd | Highly efficient gas turbine |
EP1038982A1 (en) * | 1999-03-26 | 2000-09-27 | Howmet Research Corporation | Single crystal superalloy articles with reduced grain recrystallization |
EP1054072B1 (en) * | 1999-05-20 | 2003-04-02 | ALSTOM (Switzerland) Ltd | Nickel base superalloy |
EP1204776B1 (en) * | 1999-07-29 | 2004-06-02 | Siemens Aktiengesellschaft | High-temperature part and method for producing the same |
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2000
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- 2000-11-30 EP EP00403362A patent/EP1211336B1/en not_active Expired - Lifetime
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2001
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- 2001-11-30 JP JP2001365810A patent/JP2002194467A/en active Pending
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- 2003-08-07 US US10/636,024 patent/US20040069380A1/en not_active Abandoned
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JP2002194467A (en) | 2002-07-10 |
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