EP0438338A1 - Process for making a product from pre-alloyed powders and the product obtained from the said process - Google Patents
Process for making a product from pre-alloyed powders and the product obtained from the said process Download PDFInfo
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- EP0438338A1 EP0438338A1 EP91400064A EP91400064A EP0438338A1 EP 0438338 A1 EP0438338 A1 EP 0438338A1 EP 91400064 A EP91400064 A EP 91400064A EP 91400064 A EP91400064 A EP 91400064A EP 0438338 A1 EP0438338 A1 EP 0438338A1
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C1/00—Making non-ferrous alloys
- C22C1/04—Making non-ferrous alloys by powder metallurgy
- C22C1/0433—Nickel- or cobalt-based alloys
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
- B22F1/14—Treatment of metallic powder
- B22F1/142—Thermal or thermo-mechanical treatment
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- the present invention relates to a process for obtaining a product from pre-alloyed powders, and more particularly to a process for obtaining in which the powders are subjected to a densification treatment.
- the present invention also relates to the products obtained using said process.
- powder metallurgy in development for several years, allows in particular the manufacture of parts, from metals, impossible or difficult to implement otherwise, for example in super-refractory alloys. As a result, powder metallurgy has, in particular, important applications in the field of aeronautical manufacturing (parts of turbines).
- An object of the invention is to propose a process for obtaining products from pre-alloyed powders made of super-refractory alloy which overcomes these drawbacks.
- the invention proposes a process for obtaining comprising treatments intended to increase the size of the grains, the size powder particles being nevertheless always initially limited by sieving, and the scale of segregations being reduced to dimensions which do not exceed the size of said particles.
- the Applicant has observed that during the densification stages, for example by hot isostatic compaction or by spinning, the elements segregated on the surface of the powder particles (mainly carbon and oxygen ) precipitated there, thus forming stable networks impossible to reabsorb by subsequent treatments.
- One consequence of this phenomenon is to promote interparticle ruptures and to make it impossible to magnify the grain. As a result, the grain is limited to the size of the initial powder particles.
- the invention proposes a process for obtaining one of which is a treatment making it possible to attenuate the "decoration" of the particles by precipitation of the segregated elements.
- the solution adopted by the applicant consists in subjecting, before compaction, the powders of the alloy to heat treatments under low pressure (or without pressure) by which the segregated elements precipitate internally, in phases stable at temperature. compaction and no longer during compaction on the surface of the particles.
- the Applicant has also observed that the grain enlargement treatments by temperature rise were limited by burning phenomena, that is to say the start of local melting, which prevented bring the powder alloy to the desired temperatures.
- the invention proposes, in combination with the aforementioned non-pressure or low-pressure treatments, to subject the powders or alloys to homogenization treatments, intended to structurally standardize the materials, in order to ascend as much as possible the temperature where these burning phenomena appear.
- the homogenization treatments according to the invention are heat treatments above the Solvus temperature of the alloy.
- the subject of the invention is therefore a process for obtaining a product from pre-alloyed powders, in which said powders are subjected to a densification treatment, this process being characterized in that said powders are previously subjected to a pretreatment without pressure or under low pressure at a precipitation temperature for segregation in stable phases
- the precipitation temperature of the segregations to which the powders are subjected during the pre-treatment without pressure or under low pressure is chosen between the Solvus temperature of the alloy reduced about 100 ° C and its melting temperature.
- one of the steps of the method is a heat treatment at a temperature higher than the Solvus temperature of the alloy.
- the densification treatment comprises a step of compaction at low pressure.
- the densification treatment includes a consolidation step, in particular by hot isostatic compaction or by spinning.
- Processing densification can include both a low pressure compaction step and a later consolidation step
- the heat treatment at a temperature higher than the Solvus temperature of the alloy is carried out after the densification treatment.
- the heat treatment at a temperature above the Solvus temperature of the alloy is carried out during the pre-treatment without pressure or under low pressure and / or during the densification treatment.
- the consolidation step can in particular comprise an isostatic compaction at a temperature higher than the Solvus temperature of the alloy.
- the subject of the invention is also a product of structural hardening alloy obtained from such a process, and more particularly of product of nickel-based super-refractory alloy.
- yet another object of the invention is the use of products obtained using said process, in critical parts operating at high temperatures, for example above 650 ° C., and more particularly the use of such products for the manufacture of critical parts in the field of aeronautical construction.
- the process according to the invention was used to obtain a first alloy known under the trade name ASTROLOY® (registered trademark), the weight composition of which is as follows: 0.040% zirconium: 0.023% boron ; 0.020% carbon; 3.5% titanium; 4% aluminum; 5% molybdenum; 15% chromium; 17% cobalt; nickel balance.
- ASTROLOY® registered trademark
- This alloy has a Solvius temperature of 1140 ° C.
- a classic process for obtaining a product based on pre-alloyed powders in the aforementioned weight proportions, consists of a densification treatment at high temperature and under pressure, for example a heat treatment under 100 MPa for six hours.
- Table A below gives, in ASTM standard, the grain sizes obtained as a function of the temperature of this heat treatment, this from powder particles having an average diameter of less than 75 micrometers.
- An example of a process according to the invention for its part, consists of a preliminary heat treatment of the powders under low pressure (less than 1 atm) or without pressure for 24 hours, then in a densification heat treatment, a step is a step of hot isostatic compaction, at 100 MPa for six hours, at 1160 ° C., this step of hot isostatic compaction being able to be followed by a treatment, for four hours at a temperature of 1200 ° C.
- the results on the grain sizes are still very much improved when the obtaining process comprises a final treatment step at 1200 ° C., the metallurgical grain sizes produced being able to go up to a value of 1 in ASTM standard.
- FIG. 1 represents a micrograph of an ASTROLOY alloy obtained from that of the processes in accordance with the invention cited in table B, which comprises a final processing step at 1200 ° C, it can be seen that the metallurgical grains, the limits of which appear in solid lines, have developed beyond the initial limits of the powder particles, which can be seen in dotted lines on the micrograph, due to the persistence weak decorations despite the process of implementation.
- the process according to the invention was also applied to obtain a second alloy known under the trade name N18, the weight composition of which is as follows: 0.030% zirconium; 0.015% boron; 0.015% carbon; 0.25% hafnium; 4.35% titanium; 4.35% aluminum; 6.5% molybdenum; 11.5% chromium; 15.7% cobalt; nickel balance.
- This alloy has a Solvus temperature of 1195 ° C.
- Table C gives the grain sizes obtained for this second alloy, from conventional production methods, that is to say by hot isostatic compaction at 100 MPa, for six hours, for different compaction temperatures, the initial powders with an average diameter of less than 75 ⁇ m.
- Table D gives, for its part, values of grain sizes of alloys produced for initial powders of similar dimensions, from production methods in accordance with the invention.
- These production processes each include thermal pretreatments under low pressure (less than 1 atm) or without pressure, followed by a densification treatment.
- Such densification treatment may include a consolidation step by conventional hot isostatic compaction, whether or not followed by a subsequent consolidation step.
- the densification treatment can also consist of an isostatic compaction step under low pressure, followed by a posterior compaction step.
- Figures 3 and 4 respectively represent micrographs of an alloy N18 treated according to, on the one hand, the state of the art at 1160 ° C, for 6 hours, under 100 MPa, and, according to, on the other hand, a process according to the invention consisting of a pretreatment at 1170 ° C for 24 hours, followed by isostatic compaction at low pressure at 1170 ° C, for 4 hours at 10 MPa, followed by further compaction after 1200 ° C, for 6 hours at 100 PMa, we see that l 'We clearly see in Figure 4, the limits of the metallurgical grains formed in the alloy by the process of obtaining according to the invention, while these same limits are difficult to distinguish on the micrograph shown in Figure 3, c 'is to say on the alloy obtained by a process according to the state of the art. The grains of the alloys obtained with the process according to the invention are very much higher than those obtained with the process according to the state of the art.
- FIG. 2 is a graph giving the grain size, in ASTM standard, of the alloys obtained using a process in accordance with the invention, as a function of the pretreatment temperature to which said alloys are subjected for 24 hours, this pretreatment having been followed by a step of hot isostatic compaction at 1120 ° C, for six hours, under 100 MPa, extended by a step of compaction after 1200 ° C for six hours, at 100 MPa, there is a significant increase in the value of the grain sizes when the temperature of the initial pretreatment is above the Solvus temperature of the alloy (1195 ° C.).
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Abstract
Description
La présente invention est relative à un procédé d'obtention de produit à partir de poudres préalliées, et plus particulièrement à un procédé d'obtention dans lequel les poudres sont soumises à un traitement de densification.The present invention relates to a process for obtaining a product from pre-alloyed powders, and more particularly to a process for obtaining in which the powders are subjected to a densification treatment.
La présente invention concerne aussi les produits obtenus à l'aide dudit procédé.The present invention also relates to the products obtained using said process.
On sait que la métallurgie des poudres, en développement depuis plusieurs années, permet notamment la fabrication de pièces, à partir de métaux, impossibles ou difficiles à mettre en oeuvre autrement, par exemple en alliages superréfractaires. De ce fait, la métallurgie des poudres a, en particulier, des applications importantes dans le domaine de la fabrication aéronautique (pièces de turbines).It is known that powder metallurgy, in development for several years, allows in particular the manufacture of parts, from metals, impossible or difficult to implement otherwise, for example in super-refractory alloys. As a result, powder metallurgy has, in particular, important applications in the field of aeronautical manufacturing (parts of turbines).
Cependant, si les matériaux réalisés avec les procédés d'obtention actuels présentent d'excellentes propriétés mécaniques aux moyennes températures, du fait de la finesse des grains, leur comportement à des températures élevées (au-delà de 650°C) n'est pas toujours satisfaisant, notamment en ce qui concerne leur tenue au fluage et leur résistance à la propagation des fissures.However, if the materials produced with the current production processes have excellent mechanical properties at medium temperatures, due to the fineness of the grains, their behavior at high temperatures (above 650 ° C.) is not still satisfactory, particularly with regard to their creep resistance and their resistance to crack propagation.
Un but de l'invention est de proposer un procédé d'obtention de produits à partir de poudres préalliées en alliage superréfractaire permettant de pallier ces inconvénients.An object of the invention is to propose a process for obtaining products from pre-alloyed powders made of super-refractory alloy which overcomes these drawbacks.
De façon surprenante, alors que jusqu'à présent en métallurgie des poudres, les matériaux réalisés étaient caractérisés par un grain métallurgique très fin, l'invention propose un procédé d'obtention comportant des traitements destinés à faire grossir la taille des grains, la taille des particules de poudres étant néanmoins toujours initialement limitée par tamisage, et l'échelle des ségrégations étant réduite à des dimensions qui ne dépassent pas la taille desdites particules.Surprisingly, while until now in powder metallurgy, the materials produced have been characterized by a very fine metallurgical grain, the invention proposes a process for obtaining comprising treatments intended to increase the size of the grains, the size powder particles being nevertheless always initially limited by sieving, and the scale of segregations being reduced to dimensions which do not exceed the size of said particles.
On sait, en métallurgie classique, qu'il est possible de faire grossir la taille des grains d'un alliage en lui faisant subir un traitement thermique. Cependant, dans le cadre de la métallurgie des poudres, de tels traitements thermiques s'avèrent en pratique inefficaces, par exemple les grains d'alliage obtenus à partir de poudres de diamètre inférieur à 106 micromètres, étant notamment très difficile à grossir au-delà de 7 en norme ASTM.We know, in classical metallurgy, that it is possible enlarging the grain size of an alloy by subjecting it to a heat treatment. However, in the context of powder metallurgy, such heat treatments prove in practice to be ineffective, for example the alloy grains obtained from powders with a diameter of less than 106 micrometers, being in particular very difficult to magnify beyond of 7 in ASTM standard.
En cherchant à analyser les causes de ces limitations, la demanderesse a observé que lors des étapes de densification, par exemple par compaction isostatique à chaud ou par filage, les éléments ségrégés à la surface des particules de poudre (principalement le carbone et l'oxygène) y précipitaient, formant ainsi des réseaux stables impossibles à résorber par des traitements ultérieurs. Une conséquence de ce phénomène est de favoriser les ruptures interparticulaires et de rendre impossible le grossissement du grain. De ce fait, le grain se trouve limité à la taille des particules de poudre initiale.In seeking to analyze the causes of these limitations, the Applicant has observed that during the densification stages, for example by hot isostatic compaction or by spinning, the elements segregated on the surface of the powder particles (mainly carbon and oxygen ) precipitated there, thus forming stable networks impossible to reabsorb by subsequent treatments. One consequence of this phenomenon is to promote interparticle ruptures and to make it impossible to magnify the grain. As a result, the grain is limited to the size of the initial powder particles.
Dans un de ses aspects principaux, l'invention propose un procédé d'obtention dont une étape est un traitement permettant d'atténuer la "décoration" des particules par précipitation des éléments ségrégés. Plus particulièrement, la solution retenue par la demanderesse consiste à soumettre, avant compaction, les poudres de l'alliage à des traitements thermiques sous faible pression (ou sans pression) par lesquels les éléments ségrégés précipitent de façon interne, en phases stables à la température de compaction et non plus au cours de compaction sur la surface des particules.In one of its main aspects, the invention proposes a process for obtaining one of which is a treatment making it possible to attenuate the "decoration" of the particles by precipitation of the segregated elements. More particularly, the solution adopted by the applicant consists in subjecting, before compaction, the powders of the alloy to heat treatments under low pressure (or without pressure) by which the segregated elements precipitate internally, in phases stable at temperature. compaction and no longer during compaction on the surface of the particles.
Par ailleurs, dans le cadre de son analyse, la demanderesse a encore observé que les traitements de grossissement des grains par élévation de température étaient limités par des phénomènes de brûlure, c'est-à-dire de début de fusion locale, qui empêchaient de porter l'alliage de poudre aux températures souhaitées.Furthermore, as part of its analysis, the Applicant has also observed that the grain enlargement treatments by temperature rise were limited by burning phenomena, that is to say the start of local melting, which prevented bring the powder alloy to the desired temperatures.
Pour remédier à cette autre limitation, l'invention propose, en combinaison avec les traitements sans pression ou sous faible pression précités, de soumettre les poudres ou alliages à des traitements d'homogénéisation, destinés à uniformiser structurellement les matériaux, afin de remonter autant que possible la température où apparaissent ces phénomènes de brûlure.To overcome this other limitation, the invention proposes, in combination with the aforementioned non-pressure or low-pressure treatments, to subject the powders or alloys to homogenization treatments, intended to structurally standardize the materials, in order to ascend as much as possible the temperature where these burning phenomena appear.
Plus particulièrement, dans le cas d'alliages à durcissement structural, les traitements d'homogénéisation, selon l'invention sont des traitements thermiques au-dessus de la température de Solvus de l'alliage.More particularly, in the case of alloys with structural hardening, the homogenization treatments according to the invention are heat treatments above the Solvus temperature of the alloy.
L'invention a donc pour objet un procédé d'obtention d'un produit à partir de poudres préalliées, dans lequel lesdites poudres sont soumises à un traitement de densification, ce procédé étant caractérisé par le fait que lesdites poudres sont préalablement soumises à un prétraitement sans pression ou sous faible pression à une température de précipitation des ségrégations en phases stablesThe subject of the invention is therefore a process for obtaining a product from pre-alloyed powders, in which said powders are subjected to a densification treatment, this process being characterized in that said powders are previously subjected to a pretreatment without pressure or under low pressure at a precipitation temperature for segregation in stable phases
Avantageusement, dans le cas où l'alliage obtenu est un alliage à durcissement structural, la température de précipitation des ségrégations à laquelle sont soumises les poudres lors du prétraitement sans pression ou sous faible pression est choisie entre la température de Solvus de l'alliage diminuée de 100°C environ et sa température de fusion.Advantageously, in the case where the alloy obtained is a structural hardening alloy, the precipitation temperature of the segregations to which the powders are subjected during the pre-treatment without pressure or under low pressure is chosen between the Solvus temperature of the alloy reduced about 100 ° C and its melting temperature.
De façon avantageuse, encore, toujours dans le cas où l'alliage obtenu est un alliage à durcissement structural, une des étapes du procédé est un traitement thermique à une température supérieure à la température de Solvus de l'alliage.Advantageously, again, still in the case where the alloy obtained is a structural hardening alloy, one of the steps of the method is a heat treatment at a temperature higher than the Solvus temperature of the alloy.
De préférence, le traitement de densification comporte une étape de compaction à basse pression.Preferably, the densification treatment comprises a step of compaction at low pressure.
De préférence encore, le traitement de densification comporte une étape de consolidation, notamment par compaction isostatique à chaud ou par filage. Le traitement de densification peut comporter à la fois une étape de compaction à basse pression et une étape postérieure de consolidationMore preferably, the densification treatment includes a consolidation step, in particular by hot isostatic compaction or by spinning. Processing densification can include both a low pressure compaction step and a later consolidation step
Dans un mode de mise en oeuvre préférentiel, le traitement thermique à une température supérieure à la température de Solvus de l'alliage est réalisé après le traitement de densification.In a preferred embodiment, the heat treatment at a temperature higher than the Solvus temperature of the alloy is carried out after the densification treatment.
Dans un autre mode de mise en oeuvre préférentiel, le traitement thermique à une température supérieure à la température de Solvus de l'alliage est réalisé lors du prétraitement sans pression ou sous faible pression et/ou lors du traitement de densification. L'étape de consolidation peut notamment comprendre une compaction isostatique à une température supérieure à la température de Solvus de l'alliage.In another preferred embodiment, the heat treatment at a temperature above the Solvus temperature of the alloy is carried out during the pre-treatment without pressure or under low pressure and / or during the densification treatment. The consolidation step can in particular comprise an isostatic compaction at a temperature higher than the Solvus temperature of the alloy.
L'invention a aussi pour objet un produit en alliage à durcissement structural obtenu à partir d'un tel procédé, et plus particulièrement en produit en alliage superréfractaire à base de nickel.The subject of the invention is also a product of structural hardening alloy obtained from such a process, and more particularly of product of nickel-based super-refractory alloy.
Enfin, un autre objet de l'invention encore est l'utilisation de produits obtenus à l'aide dudit procédé, dans des pièces critiques fonctionnant à des températures élevées, par exemple supérieures à 650°C, et plus particulièrement l'utilisation de tels produits pour la fabrication de pièces critiques dans le domaine de la construction aéronautique.Finally, yet another object of the invention is the use of products obtained using said process, in critical parts operating at high temperatures, for example above 650 ° C., and more particularly the use of such products for the manufacture of critical parts in the field of aeronautical construction.
La description qui suit est purement illustrative et non limitative. Elle doit être lue en regard des dessins annexés.The description which follows is purely illustrative and not limiting. It should be read in conjunction with the accompanying drawings.
Sur ces dessins:
- La Figure 1 représente une micrographie illustrant, pour un premier alliage, la croissance des grains métallurgiques au-delà des limites des particules de poudre initiales, grâce à la mise en oeuvre d'un procédé conforme à l'invention;
- La Figure 2 est un graphe illustrant la croissance des grains métallurgiques d'un deuxième alliage, grâce à la mise en oeuvre d'un procédé conforme à l'invention;
- Les Figures 3 et 4 sont des micrographies illustrant respectivement, pour le même deuxième alliage, les différences de tailles de grains métallurgiques de matériaux obtenus, d'une part, avec un procédé d'obtention conforme à l'état de l'art, et, d'autre part, avec un procédé d'obtention conforme à l'invention.
- FIG. 1 represents a micrograph illustrating, for a first alloy, the growth of metallurgical grains beyond the limits of the initial powder particles, thanks to the implementation of a process in accordance with the invention;
- Figure 2 is a graph illustrating the growth of metallurgical grains of a second alloy, thanks to the implementation of a method according to the invention;
- FIGS. 3 and 4 are micrographs respectively illustrating, for the same second alloy, the differences in size of metallurgical grains of materials obtained, on the one hand, with a process for obtaining conforming to the state of the art, and , on the other hand, with a process for obtaining according to the invention.
Le procédé conforme à l'invention a été mis en oeuvre pour l'obtention d'un premier alliage connu sous la dénomination commerciale ASTROLOY® (Marque déposée), dont la composition pondérale est la suivante: 0,040% de zirconium: 0,023% de bore; 0,020% de carbone; 3,5% de titane; 4% d'aluminium; 5% de molybdène; 15% de chrome; 17% de cobalt; balance de nickel. Cet alliage admet une température de Solvius de 1140°C.The process according to the invention was used to obtain a first alloy known under the trade name ASTROLOY® (registered trademark), the weight composition of which is as follows: 0.040% zirconium: 0.023% boron ; 0.020% carbon; 3.5% titanium; 4% aluminum; 5% molybdenum; 15% chromium; 17% cobalt; nickel balance. This alloy has a Solvius temperature of 1140 ° C.
Un procédé classique d'obtention d'un produit. à base de poudres préalliées dans les proportions pondérales précitées, consiste en un traitement de densification à haute température et sous pression, par exemple en un traitement thermique sous 100 MPa pendant six heures. Le tableau A ci-dessous donne, en norme ASTM, les tailles de grains obtenues en fonction de la température de ce traitement thermique, ce à partir de particules de poudre ayant un diamètre moyen inférieur à 75 micromètres.
Un exemple de procédé d'obtention conforme à l'invention consiste, quant à lui, en un traitement thermique préalable des poudres sous faible pression (inférieure à 1 atm) ou sans pression pendant, 24 heures, puis en un traitement thermique de densification dont une étape est une étape de compaction isostatique à chaud, sous 100 MPa pendant six heures, à 1160°C, cette étape de compaction isostatique à chaud pouvant être suivie par un traitement, pendant quatre heures à une température de 1200°C.An example of a process according to the invention, for its part, consists of a preliminary heat treatment of the powders under low pressure (less than 1 atm) or without pressure for 24 hours, then in a densification heat treatment, a step is a step of hot isostatic compaction, at 100 MPa for six hours, at 1160 ° C., this step of hot isostatic compaction being able to be followed by a treatment, for four hours at a temperature of 1200 ° C.
Les tailles de grains obtenues à partir de poudres initiales ayant un diamètre moyen inférieur à 75 µm sont données dans le tableau B suivant:
Il ressort clairement de la comparaison des Tableaux A et B, que la mise en oeuvre d'un prétraitement thermique sous faible pression ou sans pression permet un accroîssement notable des tailles de grain des alliages obtenus.It is clear from the comparison of Tables A and B, that the implementation of a heat pretreatment under low pressure or without pressure allows a significant increase in the grain sizes of the alloys obtained.
On note aussi, à partir du tableau B, que les tailles de grains sont beaucoup plus importantes lorsque le prétraitement est réalisé à 1160°C, c'est-à-dire au-dessus de la température de Solvus de l'alliage, que lorsqu'il est réalisé à 1120°CIt is also noted, from table B, that the grain sizes are much larger when the pretreatment is carried out at 1160 ° C., that is to say above the Solvus temperature of the alloy, than when performed at 1120 ° C
En outre, on constate encore, que les résultats sur les tailles de grain sont encore très nettement améliorés lorsque le procédé d'obtention comporte une dernière étape de traitement à 1200°C, les tailles de grain métallurgiques réalisées pouvant aller jusqu'à une valeur de 1 en norme ASTM.In addition, it can also be seen that the results on the grain sizes are still very much improved when the obtaining process comprises a final treatment step at 1200 ° C., the metallurgical grain sizes produced being able to go up to a value of 1 in ASTM standard.
Si l'on réfère, par ailleurs, à la Figure 1, qui représente une micrographie d'un alliage d'ASTROLOY obtenu à partir de celui des procédés conformes à l'invention cités dans le tableau B, qui comporte une dernière étape de traitement à 1200°C, on constate que les grains métallurgiques, dont les limites apparaîssent en trait continu, se sont développés au-delà des limites initiales des particules de poudre, que l'on aperçoit en pointillés sur la micrographie, du fait de la persistance de faibles décorations malgré le procédé de mise en oeuvre.If we refer, moreover, to FIG. 1, which represents a micrograph of an ASTROLOY alloy obtained from that of the processes in accordance with the invention cited in table B, which comprises a final processing step at 1200 ° C, it can be seen that the metallurgical grains, the limits of which appear in solid lines, have developed beyond the initial limits of the powder particles, which can be seen in dotted lines on the micrograph, due to the persistence weak decorations despite the process of implementation.
Le procédé conforme à l'invention a encore été appliqué pour obtenir un deuxième alliage connu sous la dénomination commerciale N18, dont la composition pondérale est la suivante: 0,030% de zirconium; 0,015% de bore; 0,015% de carbone; 0,25% d'hafnium; 4,35% de titane; 4,35% d'aluminium; 6,5% de molybdène; 11,5% de chrome; 15,7% de cobalt; balance de nickel. Cet alliage a une température de Solvus de 1195°C.The process according to the invention was also applied to obtain a second alloy known under the trade name N18, the weight composition of which is as follows: 0.030% zirconium; 0.015% boron; 0.015% carbon; 0.25% hafnium; 4.35% titanium; 4.35% aluminum; 6.5% molybdenum; 11.5% chromium; 15.7% cobalt; nickel balance. This alloy has a Solvus temperature of 1195 ° C.
Le Tableau C donne les tailles de grain obtenues pour ce deuxième alliage, à partir de procédés d'obtention classiques, c'est-à-dire par compaction isostatique à chaud sous 100 MPa, pendant six heures, pour différentes températures de compaction, les poudres initiales ayant un diamètre moyen inférieur à 75 µm.
Le Tableau D donne quant à lui, des valeurs de tailles de grain d'alliages réalisés pour des poudres initiales de dimensions similaires, à partir de procédés d'obtention conformes à l'invention. Ces procédés d'obtention comportent chacun des prétraitements thermiques sous faible pression (inférieure à 1 atm) ou sans pression, suivi d'un traitement de densification. Un tel traitement de densification peut comporter une étape de consolidation par compaction isostatique à chaud classique, suivie ou non d'une étape postérieure de consolidation. Le traitement de densification peut aussi consister en une étape de compaction isostatique sous basse pression, suivie d'une étape de compaction postérieure.
Il ressort de la comparaison des Tableaux C et D, que le prétraitement thermique des poudres sous faible pression permet de réaliser des alliages ayant des tailles de grain importantes, notamment ayant une valeur en norme ASTM inférieure ou égale à 5.It appears from the comparison of Tables C and D, that the heat pretreatment of the powders under low pressure makes it possible to produce alloys with large grain sizes, in particular having a value in ASTM standard less than or equal to 5.
Il faut aussi noter que les résultats obtenus sur ces tailles de grain sont d'autant meilleurs, que les températures de prétraitement ou de traitement thermique sont supérieures à la température de Solvus de l'alliage (1195°C).It should also be noted that the results obtained on these grain sizes are all the better, as the pre-treatment or heat treatment temperatures are higher than the Solvus temperature of the alloy (1195 ° C.).
En outre, on notera encore que les résultats obtenus avec une étape de compaction isostatique intermédiaire à basse pression (10 MPa) sont très nettement supérieurs aux autres, les valeurs des tailles de grain atteintes pouvant aller jusqu'à - 2 en norme ASTM.In addition, it will also be noted that the results obtained with an intermediate isostatic compaction step at low pressure (10 MPa) are very clearly superior to the others, the values of the grain sizes reached being able to range up to −2 in ASTM standard.
Si l'on se réfère maintenant aux Figures 3 et 4, qui représentent des micrographies respectivement d'un alliage N18 traité selon, d'une part, l'état de la technique à 1160°C, pendant 6 heures, sous 100 MPa, et, selon, d'autre part, un procédé conforme à l'invention consistant en un prétraitement à 1170°C pendant 24 heures, suivi d'une compaction isostatique sous faible pression à 1170°C, pendant 4 heures sous 10 MPa, suivie encore d'une compaction postérieure à 1200°C, pendant 6 heures sous 100 PMa, on voit que l'on distingue très nettement sur la Figure 4, les limites des grains métallurgiques formés dans l'alliage par le procédé d'obtention conforme à l'invention, alors que ces mêmes limites sont difficilement distinguables sur la micrographie représentée sur la Figure 3, c'est-à-dire sur l'alliage obtenu par un procédé conforme à l'état de la technique. Les grains des alliages obtenus avec le procédé conforme à l'invention sont très nettement supérieurs à ceux obtenus avec le procédé conforme à l'état de la technique.If we now refer to Figures 3 and 4, which respectively represent micrographs of an alloy N18 treated according to, on the one hand, the state of the art at 1160 ° C, for 6 hours, under 100 MPa, and, according to, on the other hand, a process according to the invention consisting of a pretreatment at 1170 ° C for 24 hours, followed by isostatic compaction at low pressure at 1170 ° C, for 4 hours at 10 MPa, followed by further compaction after 1200 ° C, for 6 hours at 100 PMa, we see that l 'We clearly see in Figure 4, the limits of the metallurgical grains formed in the alloy by the process of obtaining according to the invention, while these same limits are difficult to distinguish on the micrograph shown in Figure 3, c 'is to say on the alloy obtained by a process according to the state of the art. The grains of the alloys obtained with the process according to the invention are very much higher than those obtained with the process according to the state of the art.
Si l'on se réfère maintenant à la Figure 2, qui est un graphe donnant la taille des grains, en norme ASTM, des alliages obtenus à l'aide d'un procédé conforme à l'invention, en fonction de la température de prétraitement auxquels lesdits alliages sont soumis pendant 24 heures, ce prétraitement ayant été suivi par une étape de compaction isostatique à chaud à 1120°C, pendant six heures, sous 100 MPa, prolongée par une étape de compaction postérieure à 1200°C pendant six heures, sous 100 MPa, on note un accroîssement sensible de la valeur des tailles des grains lorsque la température du prétraitement initiale est au-delà de la température de Solvus de l'alliage (1195°C).If we now refer to FIG. 2, which is a graph giving the grain size, in ASTM standard, of the alloys obtained using a process in accordance with the invention, as a function of the pretreatment temperature to which said alloys are subjected for 24 hours, this pretreatment having been followed by a step of hot isostatic compaction at 1120 ° C, for six hours, under 100 MPa, extended by a step of compaction after 1200 ° C for six hours, at 100 MPa, there is a significant increase in the value of the grain sizes when the temperature of the initial pretreatment is above the Solvus temperature of the alloy (1195 ° C.).
Claims (13)
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| FR9000454A FR2657032A1 (en) | 1990-01-16 | 1990-01-16 | PROCESS FOR OBTAINING A PRODUCT FROM PRE-ALLOYED POWDERS AND A PRODUCT OBTAINED FROM SAID PROCESS. |
| FR9000454 | 1990-01-16 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| EP0438338A1 true EP0438338A1 (en) | 1991-07-24 |
| EP0438338B1 EP0438338B1 (en) | 1995-06-07 |
Family
ID=9392818
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| EP91400064A Expired - Lifetime EP0438338B1 (en) | 1990-01-16 | 1991-01-11 | Process for making a product from pre-alloyed powders and the product obtained from the said process |
Country Status (4)
| Country | Link |
|---|---|
| US (1) | US5395464A (en) |
| EP (1) | EP0438338B1 (en) |
| DE (1) | DE69110139T2 (en) |
| FR (1) | FR2657032A1 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2010023405A2 (en) * | 2008-08-26 | 2010-03-04 | Aubert & Duval | Method for preparing a nickel superalloy part, and part thus obtained |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5462808A (en) * | 1993-09-03 | 1995-10-31 | Sumitomo Metal Industries, Ltd. | Highly rigid composite material and process for its manufacture |
| US10245639B2 (en) | 2012-07-31 | 2019-04-02 | United Technologies Corporation | Powder metallurgy method for making components |
| US10247480B2 (en) | 2017-04-28 | 2019-04-02 | General Electric Company | High temperature furnace |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3702791A (en) * | 1970-04-20 | 1972-11-14 | Nasa | Method of forming superalloys |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS55161002A (en) * | 1979-06-01 | 1980-12-15 | Kobe Steel Ltd | Steel powder for powder metallurgy |
| US4732622A (en) * | 1985-10-10 | 1988-03-22 | United Kingdom Atomic Energy Authority | Processing of high temperature alloys |
| US5009704A (en) * | 1989-06-28 | 1991-04-23 | Allied-Signal Inc. | Processing nickel-base superalloy powders for improved thermomechanical working |
-
1990
- 1990-01-16 FR FR9000454A patent/FR2657032A1/en active Granted
-
1991
- 1991-01-11 DE DE69110139T patent/DE69110139T2/en not_active Expired - Lifetime
- 1991-01-11 EP EP91400064A patent/EP0438338B1/en not_active Expired - Lifetime
-
1994
- 1994-04-07 US US08/224,194 patent/US5395464A/en not_active Expired - Lifetime
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3702791A (en) * | 1970-04-20 | 1972-11-14 | Nasa | Method of forming superalloys |
Non-Patent Citations (1)
| Title |
|---|
| PATENT ABSTRACTS OF JAPAN, vol. 5, no. 37 (M-58)[709], 10 mars 1981; & JP-A-55 161 002 (KOBE SEIKOSHO K.K.) 15-12-1980 * |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2010023405A2 (en) * | 2008-08-26 | 2010-03-04 | Aubert & Duval | Method for preparing a nickel superalloy part, and part thus obtained |
| FR2935396A1 (en) * | 2008-08-26 | 2010-03-05 | Aubert & Duval Sa | PROCESS FOR THE PREPARATION OF A NICKEL - BASED SUPERALLIATION WORKPIECE AND PIECE THUS OBTAINED |
| WO2010023405A3 (en) * | 2008-08-26 | 2014-09-04 | Aubert & Duval | Method for preparing a nickel superalloy part, and part thus obtained |
| US8889064B2 (en) | 2008-08-26 | 2014-11-18 | Aubert & Duval | Method for preparing a nickel superalloy part, and the part thus obtained |
Also Published As
| Publication number | Publication date |
|---|---|
| DE69110139T2 (en) | 1996-01-04 |
| FR2657032B1 (en) | 1995-01-27 |
| DE69110139D1 (en) | 1995-07-13 |
| FR2657032A1 (en) | 1991-07-19 |
| US5395464A (en) | 1995-03-07 |
| EP0438338B1 (en) | 1995-06-07 |
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