EP0282421A2 - Aluminium alloy product containing lithium resistant to corrosion under tension and process for production - Google Patents
Aluminium alloy product containing lithium resistant to corrosion under tension and process for production Download PDFInfo
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- EP0282421A2 EP0282421A2 EP88420046A EP88420046A EP0282421A2 EP 0282421 A2 EP0282421 A2 EP 0282421A2 EP 88420046 A EP88420046 A EP 88420046A EP 88420046 A EP88420046 A EP 88420046A EP 0282421 A2 EP0282421 A2 EP 0282421A2
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
- C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
- C22F1/04—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of aluminium or alloys based thereon
- C22F1/057—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of aluminium or alloys based thereon of alloys with copper as the next major constituent
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C21/00—Alloys based on aluminium
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
- C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
- C22F1/04—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of aluminium or alloys based thereon
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
- C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
- C22F1/04—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of aluminium or alloys based thereon
- C22F1/047—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of aluminium or alloys based thereon of alloys with magnesium as the next major constituent
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
- C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
- C22F1/04—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of aluminium or alloys based thereon
- C22F1/053—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of aluminium or alloys based thereon of alloys with zinc as the next major constituent
Definitions
- the present invention relates to an Al alloy product containing lithium with high specific mechanical resistance and high damage tolerance, particularly resistant to corrosion under tension in the treated (quenched-tempered) state, in particular in the recrystallized state, and a process for obtaining such a product.
- Aluminum-lithium alloys which also exhibit excellent mechanical strength, toughness, ductility or fatigue properties (see Ph. MEYER, B. DUBOST - Al.Li Alloys III - Proceedings of the Third International Conference Sponsored by the Institute of Metals. Oxford July 8-11, 1985 - Baker Gregson Harris Peel London- 1986) are likely to exhibit corrosion resistance under insufficient stress, even in the rolling plane of thin sheets, when they are recrystallized.
- the products according to the invention have a particular microstructure comprising, either in addition to the solid solution, numerous and fairly coarse precipitates of intermetallic phases rich in elements Al, Cu, Li, Mg and possibly Zn, or a solid solution obtained by dissolving at low temperature.
- the corresponding process essentially consists in dissolving the alloy under consideration at low temperature, generally incomplete. other parameters of the production range, in particular of income, being unchanged, compared to usual practice.
- the invention applies to all aluminum-based alloys containing lithium, produced by molding, rapid solidification, ingot metallurgy or other production technique. It applies in particular to alloys based on Al, the main elements of which are as follows (by weight%): Li: 1.0 to 4.2% Cu: 0 to 5.5% Mg: 0 to 7.0% Zn: 0 to 15.0% with the following minor elements: Zr: 0 to 0.2 Mn: 0 to 1 Cr: 0 to 0.3 Nb: 0 to 0.2 Ni: 0 to 0.5 Fe: 0 to 0.5 If: 0 to 0.5 Other items: ⁇ 0.05 each Rest Al. It should preferably have:% Zn / 30 +% Mg / 18 +% Li / 4.2 +% Cu / 7 ⁇ 1.
- the metallographic and structural characteristics of these phases and their characteristic reticular distances in X-ray diffraction are similar to those given by the article by HK HARDY and JM SILCOK in the Al-Li-Cu system free of magnesium (Journal of the Institute of Metals, 1955-56, Vol 84, p. 423-425).
- the volume fraction of these particles increases with the overall content of Li, Cu, Mg and Zn and is higher the lower the solution temperature, according to the invention.
- This volume fraction must generally be greater than 0.6% and preferably between 1 and 4%, especially in alloy 2091. Below 0.6% the resistance to corrosion under stress may be insufficient on recrystallized products. ; above 4%, the mechanical characteristics of resistance and ductility become too weak.
- the largest dimension of the largest particles exceeds 5 ⁇ m and preferably 10 ⁇ m.
- This structure can be checked by differential thermal analysis or differential enthalpy analysis (DSC: Differential Scanning Calorimetry), the trace (thermogram) then having the following characteristics in the field of temperatures of solution and of melting beginning during a sample temperature rise programmed at a speed of 1 to 20 ° C / minute: . an apparent plateau or pseudo-plateau extending between the dissolution temperature actually carried out on the alloy and the starting melting temperature of the alloy.
- DSC Differential Scanning Calorimetry
- thermogram obtained evolves substantially like the baseline of the differential enthalpy analysis device (determined with 2 identical inert samples or without sample no reference), the longer the lower the solution temperature.
- the temperature at the start of this plateau coincides in practice with the solution temperature according to the invention or annealing, if the alloy is not dissolved, this in the case where the Differential Enthalpy Analysis is performed after these thermal operations. Tempering does not significantly change the thermogram in this high temperature range. This method allows you to find with certainty the solution solution temperature, even annealing, practiced. It thus gives, on a product treated in the final state (dissolved, possibly soaked and hardened), the physical signature of the treatment according to the invention.
- This pseudo level follows a large endothermic peak representing the re-solution of the small precipitates of equilibrium phase formed during the rise in temperature of the sample in the area preceding that of the dissolution temperatures practiced on the alloy. .
- the surface of this peak is therefore, as a result, the greater the lower the dissolution temperature according to the invention, prior to the thermal analysis, and is lower than the dissolution temperature usually practiced on the alloy.
- An alloy free of phases out of solution T2 or R that is to say an alloy of composition such as A ⁇ O having previously undergone complete dissolution of the coarse particles of phases T2 at R at high temperature according to the procedure normally known to those skilled in the art does not exhibit such a peak at around 532-550 ° C.
- the method according to the invention consists in dissolving carried out in a range of temperatures T MS lower than the usual dissolving temperature which the person skilled in the art considers to be the highest. possible to obtain the maximum mechanical resistance, due to the increased dissolution of the hardening elements.
- the dissolution time can be the same as that usually practiced at high temperature on aluminum-lithium alloys according to the prior art, generally from 10 min to 7 hours depending on the products (thin sheet to thick forged).
- Dissolution is followed by quenching carried out under the usual conditions.
- the income treatment is not modified compared to the usual practices for aluminum alloys containing lithium.
- the dissolution is preferably preceded during the manufacturing range of a possible hot keeping (with or without plastic deformation).
- This hot keeping is preferably practiced in a temperature range between 490 and 250 ° C, more particularly between 450 ° C and 350 ° C, for a time between 1 h and 48 hours, preferably between 6 h and 24 hours.
- the maximum temperature of this hot keeping must be less than or equal to that of the subsequent dissolution.
- This keeping hot may possibly be multi-level, provided that the last level is carried out according to the invention. It is preferably applied after the hot deformation phase for wrought alloys. It can possibly be followed by a cold deformation.
- the alloy is cold deformed and if this deformation requires intermediate annealing, the last of them will be carried out under the conditions defined above.
- the cooling rate after keeping hot must be greater than 10 ° C / hour and preferably greater than 25 ° C / h. This speed is the average speed between the temperature for keeping hot and 100 ° C., the cooling rate below 100 ° C. is not critical.
- the cooling can be carried out in an oven, under an air stream, with calm air, with water, or by any other technique allowing the desired cooling rates to be obtained.
- the hot keeping is carried out at too high a temperature, the resistance to corrosion under tension is greatly reduced. If the hot keeping is carried out at too low a temperature, this results in difficulties for the subsequent cold deformation or even a reduction in the resistance to corrosion under stress.
- the microstructures obtained are given in FIG. 1 with regard to the dissolution at 530 ° C. and in FIGS. 2 and 3 with regard to the dissolution at 500 ° C.
- alloy 2091 The same alloy as above (alloy 2091) was dissolved at various temperatures between 490 ° C and 535 ° C after annealing for 1 hour at 400 ° C and cold rolling, quenching with water and tempering for 12 hours at 135 ° C, before undergoing a differential thermal analysis on a DUPONT de NEMOURS DSC 910 device controlled by a DSC 990 programmer under the following conditions: - samples and reference (Refined aluminum) machined in the form of discs with a diameter of 5 mm and a thickness of 1 mm - dry nitrogen sweeping in the cell - temperature rise rate of 5 ° C / min between 400 and 590 ° C.
- thermogram we see that the temperature of the start of the detectable pseudo-level (I) - substantially straight part very slightly endothermic compared to the baseline of the device determined beforehand - corresponds, with the accuracy of the measurement and determining the phase transformation temperatures by intersection of the tangents to the thermogram, to the effective solution temperature according to the invention, and this better than 3 ° C.
- narrow peak (II) of beginning fusion of the eutectic constituents which begins around 535 ° C and ends just before the equilibrium fusion of the alloy (solidus). The latter is marked by a very deep and progressive endothermic peak (III).
- the starting melting peak appears, after thermal analysis, much deeper in the alloys treated according to the invention, than in the alloy treated at 530 ° C according to the conventional solution treatment.
- Example 1 The combination of this differential thermal analysis method and the metallographic analysis of Example 1 therefore make it possible to characterize in a reliable and new way the products produced according to the invention which is the subject of the main patent.
- a 2091 alloy with a composition by weight: 1.95% Li - 2.10% Cu - 1.5% Mg - 0.08% Zr - 0.04% Fe - 0.04% Si - aluminum residue is cast in trays 800 ⁇ 300 mm2 section, homogenized 24 hours at 527 ° C, scalped, then hot rolled between 470 and 380 ° C up to 3.6 mm thick and wound in a coil. It is then kept hot according to the invention 1 h 450 ° C. followed by 12 hours at 400 ° C (with oven cooling between the two stages). Cooling after keeping hot is carried out at a speed in the region of 35 ° C / hour to a temperature of 100 ° C. After keeping hot, the sheets are cold rolled to 1.6 mm.
- FIG. 5 confirm the good level of fatigue properties of the alloy treated according to the invention, which are superior to those of the reference alloy: 2024.
- the two types of sheet are then cold rolled up to 1.6 mm.
- the stress corrosion and mechanical strength properties measured are given in Table II.
- a 2091 alloy of composition (by weight) 2.0% Li - 1.8% Cu - 1.4% Mg - 0.12% Zr - 0.06% Fe - 0.04% Si is cast in ⁇ 50 mm billets (induction heating; spinning at 430 ° C). This bar is machined to lengths of 500 mm; these lengths were reheated and stamped in several passes between 490 and 400 ° C. Before the last stamping pass, the parts are kept hot according to the invention for 6 hours at 450 ° C. and deformed at this temperature. They then undergo cooling, the speed of which is greater than 100 ° C./h up to 100 ° C. according to the invention.
- An alloy of composition (by weight): 2.5% Li - 1.2% Cu - 1.0% Mg 0.06% Zr - 1.5% Zn - 0.06% Fe - 0.04% Si is poured into a 300 ⁇ 100 mm2 section plate, homogenized for 24 hours at 535 ° C (with rise in homogenization temperature at 25 ° C / h from 500 ° C). It is then scalped, reheated to 490 ° C, hot rolled between 480 and 300 ° C up to 3.6 mm. The raw hot rolling product thus obtained is then kept hot for 1 hour at 450 ° C., cooled by quenching in cold water and cold rolled from 3.6 to 1.2 mm.
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Abstract
Description
La présente invention concerne un produit en alliage d'Al contenant du lithium à haute résistance mécanique spécifique et haute tolérance au dommage, particulièrement résistant la corrosion sous tension à l'état traité (trempé-revenu), notamment à l'état recristallisé, et un procédé d'obtention d'un tel produit.The present invention relates to an Al alloy product containing lithium with high specific mechanical resistance and high damage tolerance, particularly resistant to corrosion under tension in the treated (quenched-tempered) state, in particular in the recrystallized state, and a process for obtaining such a product.
L'obtention d'alliages possédant une haute résistance à la corrosion sous tension, est un objectif essentiel pour les demi-produits métallurgiques destinés à une utilisation dans l'aéronautique ou l'espace.Obtaining alloys with high resistance to corrosion under stress is an essential objective for metallurgical semi-finished products intended for use in aeronautics or space.
Les alliages aluminium-lithium qui présentent par ailleurs d'excellentes propriétés de résistance mécanique, de ténacité, de ductilité ou de fatigue (voir Ph. MEYER, B. DUBOST - Al.Li Alloys III - Proceedings of the Third International Conference Sponsored by the Institute of Metals. Oxford 8-11 juillet 1985 - Baker Gregson Harris Peel London- 1986) sont susceptibles de présenter une résistance à la corrosion sous contrainte insuffisante, même dans le plan de laminage de tôles minces, lorsque celles-ci sont recristallisées.Aluminum-lithium alloys which also exhibit excellent mechanical strength, toughness, ductility or fatigue properties (see Ph. MEYER, B. DUBOST - Al.Li Alloys III - Proceedings of the Third International Conference Sponsored by the Institute of Metals. Oxford July 8-11, 1985 - Baker Gregson Harris Peel London- 1986) are likely to exhibit corrosion resistance under insufficient stress, even in the rolling plane of thin sheets, when they are recrystallized.
Cette insuffisance est de nature à limiter leur emploi; par exemple la seule pose de rivets avec forte interférence peut conduire, comme dans le cas d'alliages conventionnels sensibles à la corrosion sous tension (CST) (voir Kaneko Siemenz - Corrosion Thresholds for interference fit fasteners and cold worked holes - Stress Corrosion New Approaches ASTM - STP 610, 1976, pp. 252-266), à des fissures dues à la corrosion sous contraintes, induites par les contraintes résiduelles de rivetage.This insufficiency is likely to limit their use; for example, the mere installation of rivets with strong interference can lead, as in the case of conventional alloys sensitive to corrosion under tension (CST) (see Kaneko Siemenz - Corrosion Thresholds for interference fit fasteners and cold worked holes - Stress Corrosion New Approaches ASTM - STP 610, 1976, pp. 252-266), to cracks due to corrosion under stresses, induced by residual riveting stresses.
Les produits selon l'invention possèdent une microstructure particulière comportant, soit outre la solution solide, des précipités nombreux et assez grossiers de phases intermétalliques riches en éléments Al, Cu, Li, Mg et éventuellement Zn, soit une solution solide obtenue par mise en solution à basse température.The products according to the invention have a particular microstructure comprising, either in addition to the solid solution, numerous and fairly coarse precipitates of intermetallic phases rich in elements Al, Cu, Li, Mg and possibly Zn, or a solid solution obtained by dissolving at low temperature.
Le procédé correspondant consiste essentiellement à une mise en solution à basse température, en général incomplète, de l'alliage considéré, les autres paramètres de la gamme de fabrication, en particulier de revenu, étant inchangés, par rapport à la pratique usuelle.The corresponding process essentially consists in dissolving the alloy under consideration at low temperature, generally incomplete. other parameters of the production range, in particular of income, being unchanged, compared to usual practice.
L'invention s'applique à tous les alliages à base aluminium contenant du lithium, réalisés par moulage, solidification rapide, métallurgie du lingot ou autre technique d'élaboration.
Elle s'applique en particulier aux alliages à base d'Al dont les éléments principaux sont les suivants (en poids %) :
Li : 1.0 à 4.2 %
Cu : 0 à 5.5 %
Mg : 0 à 7.0 %
Zn : 0 à 15.0 %
avec les éléments mineurs suivants :
Zr : 0 à 0,2
Mn : 0 à 1
Cr : 0 à 0,3
Nb : 0 à 0,2
Ni : 0 à 0,5
Fe : 0 à 0,5
Si : 0 à 0,5
Autres éléments : < 0,05 chacun
Reste Al.
On doit avoir de préférence : % Zn/30 + % Mg/18 + % Li/4,2 + % Cu/7 <1.The invention applies to all aluminum-based alloys containing lithium, produced by molding, rapid solidification, ingot metallurgy or other production technique.
It applies in particular to alloys based on Al, the main elements of which are as follows (by weight%):
Li: 1.0 to 4.2%
Cu: 0 to 5.5%
Mg: 0 to 7.0%
Zn: 0 to 15.0%
with the following minor elements:
Zr: 0 to 0.2
Mn: 0 to 1
Cr: 0 to 0.3
Nb: 0 to 0.2
Ni: 0 to 0.5
Fe: 0 to 0.5
If: 0 to 0.5
Other items: <0.05 each
Rest Al.
It should preferably have:% Zn / 30 +% Mg / 18 +% Li / 4.2 +% Cu / 7 <1.
Les produits selon l'invention contiennent préférentiellement (en poids %) de 1,7 à 2,5 Li - 0,8 à 3 % Mg - 1,0 à 3,5 % Cu - jusqu'à 2 % Zn, le reste étant constitué d'Al, d'éléments secondaires tels que Zr (0 à 0,20 %), Mn, Cr, Ti et d'impuretés dont la quantité totale est inférieure ou égale à 1 % et sont traités de façon spécifique. Ils présentent une microstructure particulièrement résistante à la corrosion sous tension et comportant, outre la solution solide, des précipités nombreux et assez grossiers de phases intermétalliques riches en éléments Al, Cu, Li, Mg et le cas échéant Zn si les teneurs en ces éléments d'addition obéissent à l'inégalité suivante déterminée après étude expérimentale en métallographie:
A > O où A= % Cu + % Li + % 
The products according to the invention preferably contain (by weight%) from 1.7 to 2.5 Li - 0.8 to 3% Mg - 1.0 to 3.5% Cu - up to 2% Zn, the rest consisting of Al, secondary elements such as Zr (0 to 0.20%), Mn, Cr, Ti and impurities whose total amount is less than or equal to 1% and are treated specifically. They have a microstructure which is particularly resistant to stress corrosion and which, in addition to the solid solution, contains numerous and fairly coarse precipitates of intermetallic phases rich in elements Al, Cu, Li, Mg and if necessary Zn if the contents addition obey the following inequality determined after experimental study in metallography:
A> O where A =% Cu +% Li +%
Dans cette formule % Cu, % Li, % Mg, % Zn sont les teneurs pondérales et T la température exprimée en °C. Dans ce cas ces phases sont de type R - Al₅Cu (Li,Mg)₃ et de type T₂ - Al₆Cu (Li,Mg)₃ dans les alliages 8090 et 2091 selon la désignation de l'Aluminium Association.In this formula% Cu,% Li,% Mg,% Zn are the weight contents and T is the temperature expressed in ° C. In this case these phases are of type R - Al₅Cu (Li, Mg) ₃ and of type T₂ - Al₆Cu (Li, Mg) ₃ in alloys 8090 and 2091 according to the designation of the Aluminum Association.
Les caractéristiques métallographiques et structurales de ces phases et leurs distances réticulaires caractéristiques en diffraction de rayons X sont analogues à celles données par l'article de H.K. HARDY et J.M. SILCOK dans le système Al-Li-Cu exempt de magnésium (Journal of the Institute of Metals, 1955-56, Vol 84, p. 423-425).
La fraction volumique de ces particules augmente avec la teneur globale en Li, Cu, Mg et Zn et est d'autant plus élevée que la température de mise en solution, selon l'invention, est faible. Par analyse métallographique et structurale, la demanderesse a constaté que la fraction volumique des particules, en %, est fv = k.A si A > 0 avec 2,0 ≦ k ≦ 4,0. Cette fraction volumique doit en général être supérieure à 0,6 % et de préférence comprise entre 1 et 4 % notamment dans l'alliage 2091. En-dessous de 0,6% la tenue à la corrosion sous tension peut être insuffisante sur produits recristallisés; au-dessus de 4%, les caractéristiques mécaniques de résistance et de ductilité deviennent trop faibles.The metallographic and structural characteristics of these phases and their characteristic reticular distances in X-ray diffraction are similar to those given by the article by HK HARDY and JM SILCOK in the Al-Li-Cu system free of magnesium (Journal of the Institute of Metals, 1955-56, Vol 84, p. 423-425).
The volume fraction of these particles increases with the overall content of Li, Cu, Mg and Zn and is higher the lower the solution temperature, according to the invention. By metallographic and structural analysis, the Applicant has found that the volume fraction of the particles, in%, is fv = kA if A> 0 with 2.0 ≦ k ≦ 4.0. This volume fraction must generally be greater than 0.6% and preferably between 1 and 4%, especially in alloy 2091. Below 0.6% the resistance to corrosion under stress may be insufficient on recrystallized products. ; above 4%, the mechanical characteristics of resistance and ductility become too weak.
La plus grande dimension des plus grosses particules dépasse 5 µm et de préférence 10 µm.
Cette structure peut être contrôlée par une analyse thermique différentielle ou analyse enthalpique différentielle (DSC : Differential Scanning Calorimetry), le tracé (thermogramme) présentant alors les caractéristiques suivantes dans le domaine des températures de mise en solution et de fusion commençante au cours d'une montée en température d'échantillon programmée à une vitesse de 1 à 20°C/minute :
. un palier apparent ou pseudo-palier s'étendant entre la température de mise en solution réellement effectuée sur l'alliage et la température de fusion commençante de l'alliage.The largest dimension of the largest particles exceeds 5 µm and preferably 10 µm.
This structure can be checked by differential thermal analysis or differential enthalpy analysis (DSC: Differential Scanning Calorimetry), the trace (thermogram) then having the following characteristics in the field of temperatures of solution and of melting beginning during a sample temperature rise programmed at a speed of 1 to 20 ° C / minute:
. an apparent plateau or pseudo-plateau extending between the dissolution temperature actually carried out on the alloy and the starting melting temperature of the alloy.
Ce pseudo-palier pour lequel le thermogramme obtenu évolue sensiblement comme la ligne de base de l'appareil d'analyse enthalpique différentielle (déterminée avec 2 échantillons inertes identiques ou sans échantillon ni référence), est alors d'autant plus long que la température de mise en solution est plus basse. De plus, il est apparu lors des essais que la température du début de ce palier coïncide en pratique avec la température de mise en solution selon l'invention ou de recuit, si l'alliage n'est pas mis en solution, ceci dans le cas où l'Analyse Enthalpique Différentielle est pratiquée après ces opérations thermiques. Un revenu ne modifie pas sensiblement le thermogramme dans ce domaine de températures élevées. Cette méthode permet de retrouver avec certitude la température de mise en solution, voire de recuit, pratiquée. Elle donne ainsi, sur produit traité à l'état final (mis en solution, trempé éventuellement écroui et revenu), la signature physique du traitement selon l'invention.This pseudo-level for which the thermogram obtained evolves substantially like the baseline of the differential enthalpy analysis device (determined with 2 identical inert samples or without sample no reference), the longer the lower the solution temperature. In addition, it appeared during tests that the temperature at the start of this plateau coincides in practice with the solution temperature according to the invention or annealing, if the alloy is not dissolved, this in the case where the Differential Enthalpy Analysis is performed after these thermal operations. Tempering does not significantly change the thermogram in this high temperature range. This method allows you to find with certainty the solution solution temperature, even annealing, practiced. It thus gives, on a product treated in the final state (dissolved, possibly soaked and hardened), the physical signature of the treatment according to the invention.
Ce pseudo palier succède à un large pic endothermique représentant la remise en solution des petits précipités de phase d'équilibre formés lors de la montée en température de l'échantillon dans le domaine précédant celui des températures de mise en solution pratiquées sur l'alliage.
. un pic endothermique de fusion commençante de phase AlCuLiMg (R ou T₂ dans le domaine de composition préférentielle) dans la matrice Al vers 532 à 550°C (selon la composition de l'alliage) d'autant plus important en surface de pic (c'est-à-dire en chaleur, absorbée pour la fusion) que la fraction volumique de phase hors solution T₂ ou R est importante.
La surface de ce pic est donc, de ce fait, d'autant plus grande que la température de mise en solution selon l'invention, préalable à l'analyse thermique est faible et est inférieure à la température de mise en solution habituellement pratiquée sur l'alliage. Un alliage exempt de phases hors solution T₂ ou R, c'est-à-dire un alliage de composition telle que A < O ayant subi au préalable une mise en solution complète des particules grossières de phases T₂ à R à haute température selon la procédure normalement connue de l'homme de l'art ne présente pas de tel pic vers 532-550°C.This pseudo level follows a large endothermic peak representing the re-solution of the small precipitates of equilibrium phase formed during the rise in temperature of the sample in the area preceding that of the dissolution temperatures practiced on the alloy.
. an endothermic peak of starting AlCuLiMg phase fusion (R or T₂ in the preferred composition range) in the matrix Al around 532 at 550 ° C. (depending on the composition of the alloy) all the more important at the peak surface (c 'is to say in heat, absorbed for the fusion) that the volume fraction of phase out of solution T₂ or R is important.
The surface of this peak is therefore, as a result, the greater the lower the dissolution temperature according to the invention, prior to the thermal analysis, and is lower than the dissolution temperature usually practiced on the alloy. An alloy free of phases out of solution T₂ or R, that is to say an alloy of composition such as A <O having previously undergone complete dissolution of the coarse particles of phases T₂ at R at high temperature according to the procedure normally known to those skilled in the art does not exhibit such a peak at around 532-550 ° C.
La méthode selon l'invention consiste en une mise en solution effectuée dans un domaine de températures TMS inférieures à la température de mise en solution habituelle que l'homme de l'art tient la plus élevée possible pour obtenir la résistance mécanique maximale, par suite de la mise en solution accrue des éléments durcissants.The method according to the invention consists in dissolving carried out in a range of temperatures T MS lower than the usual dissolving temperature which the person skilled in the art considers to be the highest. possible to obtain the maximum mechanical resistance, due to the increased dissolution of the hardening elements.
TMS doit être inférieure à TM (en °C) = 474 + 18.2 % Li - 2 % Cu (% Cu-1,7) + % Mg (-17,6+3,6 % Li+4,3 % Cu) - 3 % Zn
où %Li, %Cu, %Mg, %Zn sont les % en poids des éléments d'alliage cités, mais doit rester supérieure ou égale à 460°C et de préférence à 480°C.T MS must be less than T M (in ° C) = 474 + 18.2% Li - 2% Cu (% Cu-1.7) +% Mg (-17.6 + 3.6% Li + 4.3% Cu) - 3% Zn
where% Li,% Cu,% Mg,% Zn are the% by weight of the alloying elements mentioned, but must remain greater than or equal to 460 ° C. and preferably to 480 ° C.
La durée de mise en solution peut être la même que celle usuellement pratiquée à haute température sur les alliages aluminium-lithium selon l'art antérieur, en général de 10 min à 7 heures selon les produits (tôle mince à forgés épais).The dissolution time can be the same as that usually practiced at high temperature on aluminum-lithium alloys according to the prior art, generally from 10 min to 7 hours depending on the products (thin sheet to thick forged).
Si la mise en solution est effectuée à trop haute température, il en résulte une perte très sensible de la résistance à la corrosion sous tension; par contre, si elle est effectuée à trop basse température, les caractéristiques mécaniques de résistance sont insuffisantes.If the dissolution is carried out at too high a temperature, this results in a very significant loss of resistance to corrosion under stress; on the other hand, if it is carried out at too low a temperature, the mechanical resistance characteristics are insufficient.
La mise en solution est suivie d'une trempe pratiquée dans les conditions usuelles.
Le traitement de revenu n'est pas modifié par rapport aux pratiques habituelles pour les alliages d'aluminium contenant du lithium.Dissolution is followed by quenching carried out under the usual conditions.
The income treatment is not modified compared to the usual practices for aluminum alloys containing lithium.
La mise en solution est de préférence précédée au cours de la gamme de fabrication d'un maintien à chaud éventuel (avec ou sans déformation plastique).
Ce maintien à chaud est de préférence pratiqué dans un domaine de température compris entre 490 et 250°C, plus particulièrement entre 450°C et 350°C, pendant un temps compris entre 1 h et 48 heures, de préférence entre 6 h et 24 heures.
Cependant, la température maximale de ce maintien à chaud doit être inférieure ou égale à celle de la mise en solution ultérieure.The dissolution is preferably preceded during the manufacturing range of a possible hot keeping (with or without plastic deformation).
This hot keeping is preferably practiced in a temperature range between 490 and 250 ° C, more particularly between 450 ° C and 350 ° C, for a time between 1 h and 48 hours, preferably between 6 h and 24 hours.
However, the maximum temperature of this hot keeping must be less than or equal to that of the subsequent dissolution.
Ce maintien à chaud peut être éventuellement multi-palier, à condition que le dernier palier soit effectué selon l'invention.
Il est appliqué de préférence après la phase de déformation à chaud pour les alliages de corroyage.
Il peut être éventuellement suivi d'une déformation à froid.This keeping hot may possibly be multi-level, provided that the last level is carried out according to the invention.
It is preferably applied after the hot deformation phase for wrought alloys.
It can possibly be followed by a cold deformation.
Si l'alliage est déformé à froid et si cette déformation nécessite des recuits intermédiaires, le dernier d'entre eux sera effectué dans les conditions définies ci-dessus.If the alloy is cold deformed and if this deformation requires intermediate annealing, the last of them will be carried out under the conditions defined above.
La vitesse de refroidissement après le maintien à chaud doit être supérieure à 10°C/heure et de préférence supérieure à 25°C/h. Cette vitesse est la vitesse moyenne entre la température de maintien à chaud et 100°C, la vitesse de refroidissement au-dessous de 100°C n'étant pas critique.The cooling rate after keeping hot must be greater than 10 ° C / hour and preferably greater than 25 ° C / h. This speed is the average speed between the temperature for keeping hot and 100 ° C., the cooling rate below 100 ° C. is not critical.
Le refroidissement peut être effectué en four, sous courant d'air, à l'air calme, à l'eau, ou par toute autre technique permettant d'obtenir les vitesses de refroidissement désirées.The cooling can be carried out in an oven, under an air stream, with calm air, with water, or by any other technique allowing the desired cooling rates to be obtained.
Si le maintien à chaud est effectué à trop haute température, la résistance à la corrosion sous tension est fortement diminuée. Si le maintien à chaud est effectué à trop basse température, il en résulte des difficultés pour la déformation à froid ultérieure ou même une diminution de la résistance à la corrosion sous tension.If the hot keeping is carried out at too high a temperature, the resistance to corrosion under tension is greatly reduced. If the hot keeping is carried out at too low a temperature, this results in difficulties for the subsequent cold deformation or even a reduction in the resistance to corrosion under stress.
L'invention sera mieux comprise à l'aide des exemples suivants illustrés par les figures 1 à 7.
- . La figure 1 représente la micrographie optique dans le plan long-travers court d'un alliage traité hors l'invention.
- . La figure 2 représente la micrographie dans le plan long-travers court d'un alliage traité conformément à l'invention.
- . La figure 3 représente la micrographie dans le plan long-travers long d'un alliage traité conformément à l'invention.
- . La figure 4 représente divers thermogrammes d'un alliage 2091 mis en solution à diverses températures (exemple 2).
- . La figure 5 représente les courbes d'évolution de la vitesse de propagation (da/dn) d'une fissure de fatigue en traction ondulée : σ = 90 ± 40 MPa en fonction du Δ K dans les sens LT et TL, pour les alliages selon l'invention (cas A), hors l'invention (cas B), correspondant à l'exemple 3 et pour l'alliage de référence (2024).
- . La figure 6 représente une pièce matricée traitée selon l'invention et la position relative des éprouvettes de traction et de corrosion sous tension (exemple 5).
- . La figure 7 représente la structure de l'alliage traité selon l'invention correspondant à l'exemple 6.
- . FIG. 1 represents the optical micrograph in the long-through-short plane of an alloy treated outside the invention.
- . FIG. 2 represents the micrograph in the long-through-short plane of an alloy treated in accordance with the invention.
- . FIG. 3 represents the micrograph in the long-through long plane of an alloy treated in accordance with the invention.
- . FIG. 4 represents various thermograms of an alloy 2091 dissolved in various temperatures (example 2).
- . Figure 5 represents the curves of evolution of the speed of propagation (da / dn) of a fatigue crack in wavy traction: σ = 90 ± 40 MPa according to the Δ K in the directions LT and TL, for the alloys according to the invention (case A), outside the invention (case B), corresponding to Example 3 and for the reference alloy (2024).
- . FIG. 6 represents a stamped part treated according to the invention and the relative position of the tensile and corrosion test specimens under tension (example 5).
- . FIG. 7 represents the structure of the alloy treated according to the invention corresponding to example 6.
Deux tôles de 1,6 mm d'épaisseur de composition suivante (en poids %):
Li : 2,07 - Cu : 2,15 - Mg : 1,53 - Zr : 0,10 - Ti : 0,03
Fe : 0,04 - Si 0,03 -
reste Al
ont été traitées de la façon suivante :
recuit 1 h 450°C + 12 h 400°C suivi d'une mise en solution (selon l'invention) ou 530°C, trempées à l'eau froide, tractionnées de 2% et revenues 12 h à 135°C.Two 1.6 mm thick sheets of the following composition (by weight%):
Li: 2.07 - Cu: 2.15 - Mg: 1.53 - Zr: 0.10 - Ti: 0.03
Fe: 0.04 - If 0.03 -
stay Al
were processed as follows:
annealing 1 h 450 ° C + 12 h 400 ° C followed by dissolving (according to the invention) or 530 ° C, quenched in cold water, drawn up by 2% and returned 12 h at 135 ° C.
Les microstructures obtenues sont reportées sur la figure 1 en ce qui concerne la mise en solution à 530°C et sur les figures 2 et 3 en ce qui concerne la mise en solution à 500°C. Les particules grossières, de taille nettement supérieure à 5 µm, sont essentiellement constituées de phase R-Al₅Cu(Li,Mg)₃ hors solution (point vérifié par analyse quantitative à la microsonde électronique de Castaing et par diffraction des rayons X selon la méthode Seeman-Bohlin).
Leur fraction surfaçique moyenne sur coupes polies (égale à la fraction volumique dans l'échantillon massif), mesurée par analyse d'images quantitatives sur appareil IBAS KONTRON est de 0,53% après mise en solution à 530°C (k ≃ 2,9) et de 2,3% après mise en solution à 500°C.
(k ≃ 2,7) avec une précision d'environ + ou - 10% sur cette valeur moyenne.The microstructures obtained are given in FIG. 1 with regard to the dissolution at 530 ° C. and in FIGS. 2 and 3 with regard to the dissolution at 500 ° C. The coarse particles, whose size is clearly greater than 5 µm, essentially consist of the R-Al₅Cu phase (Li, Mg) ₃ out of solution (point verified by quantitative analysis using a Castaing electron microprobe and by X-ray diffraction according to the Seeman method -Bohlin).
Their average surface fraction on polished sections (equal to the volume fraction in the bulk sample), measured by analysis of quantitative images on an IBAS KONTRON device, is 0.53% after dissolving at 530 ° C (k ≃ 2, 9) and 2.3% after dissolving at 500 ° C.
(k ≃ 2.7) with an accuracy of approximately + or - 10% on this average value.
Le même alliage que ci-dessus (alliage 2091) a été mis en solution à diverses températures comprises entre 490°C et 535°C après recuit 1h à 400°C et laminage à froid, trempe à l'eau et revenu 12 h à 135°C, avant de subir une analyse thermique différentielle sur un appareil DUPONT de NEMOURS DSC 910 piloté par un programmateur DSC 990 dans les conditions suivantes:
- échantillons et référence (Aluminium raffiné) usinés sous forme de disques de diamètre 5 mm et d'épaisseur 1 mm
- balayage d'azote sec dans la cellule
- vitesse de montée en température de 5°C/min entre 400 et 590°C.The same alloy as above (alloy 2091) was dissolved at various temperatures between 490 ° C and 535 ° C after annealing for 1 hour at 400 ° C and cold rolling, quenching with water and tempering for 12 hours at 135 ° C, before undergoing a differential thermal analysis on a DUPONT de NEMOURS DSC 910 device controlled by a DSC 990 programmer under the following conditions:
- samples and reference (Refined aluminum) machined in the form of discs with a diameter of 5 mm and a thickness of 1 mm
- dry nitrogen sweeping in the cell
- temperature rise rate of 5 ° C / min between 400 and 590 ° C.
Les thermogrammes obtenus sont reportés sur la figure 4.
Sur ces thermogrammes l'abscisse représente la température en °C et l'ordonnée la puissance (en mW) dégagée ou absorbée respectivement dans le sens exothermique (+) ou endothermique (-). La ligne de base de l'appareil (LB) est représentée en traits discontinus.
- La courbe (1) correspond à mise en solution à 490°C.
- La courbe (2) correspond à mise en solution à 510°C.
- La courbe (3) correspond à mise en solution à 520°C.
- La courbe (4) correspond à mise en solution à 530°C.
On these thermograms the abscissa represents the temperature in ° C and the ordinate the power (in mW) released or absorbed respectively in the exothermic (+) or endothermic (-) direction. The baseline of the device (LB) is shown in broken lines.
- Curve (1) corresponds to dissolution at 490 ° C.
- Curve (2) corresponds to dissolution at 510 ° C.
- Curve (3) corresponds to dissolution at 520 ° C.
- Curve (4) corresponds to dissolution at 530 ° C.
Sur chaque thermogramme on s'aperçoit que la température du début du pseudo-palier détectable (I) - partie sensiblement rectiligne très légèrement endothermique par rapport à la ligne de base de l'appareil déterminée au préalable - correspond, avec la précision de la mesure et de la détermination des températures de transformation de phases par intersection des tangentes au thermogramme, à la température effective de mise en solution selon l'invention, et ce à mieux que 3°C près.
On remarque aussi l'étroit pic (II) de fusion commençante des constituants eutectiques, qui débute vers 535°C et se termine juste avant la fusion d'équilibre de l'alliage (solidus). Cette dernière est marquée par un pic endothermique très profond et progressif (III).
Le pic de fusion commençante (endothermique) apparaît, après analyse thermique, beaucoup plus profond dans les alliages traités selon l'invention, que dans l'alliage traité à 530°C selon la mise en solution classique.On each thermogram we see that the temperature of the start of the detectable pseudo-level (I) - substantially straight part very slightly endothermic compared to the baseline of the device determined beforehand - corresponds, with the accuracy of the measurement and determining the phase transformation temperatures by intersection of the tangents to the thermogram, to the effective solution temperature according to the invention, and this better than 3 ° C.
We also note the narrow peak (II) of beginning fusion of the eutectic constituents, which begins around 535 ° C and ends just before the equilibrium fusion of the alloy (solidus). The latter is marked by a very deep and progressive endothermic peak (III).
The starting melting peak (endothermic) appears, after thermal analysis, much deeper in the alloys treated according to the invention, than in the alloy treated at 530 ° C according to the conventional solution treatment.
La combinaison de cette méthode d'analyse thermique différentielle et de l'analyse métallographique de l'exemple 1 permettent donc de caractériser de manière fiable et nouvelle les produits fabriqués selon l'invention objet du brevet principal.The combination of this differential thermal analysis method and the metallographic analysis of Example 1 therefore make it possible to characterize in a reliable and new way the products produced according to the invention which is the subject of the main patent.
Un alliage 2091 de composition en poids : 1,95% Li - 2,10% Cu - 1,5% Mg- 0,08% Zr - 0,04% Fe - 0,04% Si - reste aluminium est coulé en plateaux de section 800×300 mm², homogénéisé 24 heures à 527°C, scalpé, puis laminé à chaud entre 470 et 380°C jusqu'à 3,6 mm d'épaisseur et enroulé en bobine. Il est alors maintenu à chaud selon l'invention 1h 450°C suivi de 12 heures à 400°C (avec refroidissement en four entre les deux paliers). Le refroidissement après le maintien à chaud est effectué à une vitesse voisine de 35°C/heure jusqu'à la température de 100°C.
Après maintien à chaud, les tôles sont laminées à froid jusqu'à 1,6 mm.
Une partie des tôles minces ainsi fabriquées est alors mise en solution selon l'invention (cas A) : 20 min à 500°C ± 2°C, trempée à l'eau froide, défripée et tractionnée de 2%, enfin revenue 12 h à 135°C.
Une autre partie des tôles est mise en solution hors l'invention (cas B) 20 min à 528°C ± 2°C puis subit le même parachèvement que dans le cas A décrit ci-dessus. Dans ce cas d'alliage : TM= 505,5°C.
La structure de l'alliage est recristallisée à grains fins et équiaxes (taille moyenne : 20 µm).A 2091 alloy with a composition by weight: 1.95% Li - 2.10% Cu - 1.5% Mg - 0.08% Zr - 0.04% Fe - 0.04% Si - aluminum residue is cast in trays 800 × 300 mm² section, homogenized 24 hours at 527 ° C, scalped, then hot rolled between 470 and 380 ° C up to 3.6 mm thick and wound in a coil. It is then kept hot according to the invention 1 h 450 ° C. followed by 12 hours at 400 ° C (with oven cooling between the two stages). Cooling after keeping hot is carried out at a speed in the region of 35 ° C / hour to a temperature of 100 ° C.
After keeping hot, the sheets are cold rolled to 1.6 mm.
A part of the thin sheets thus produced is then dissolved according to the invention (case A): 20 min at 500 ° C ± 2 ° C, quenched in cold water, depleted and pulled by 2%, finally returned 12 h at 135 ° C.
Another part of the sheets is dissolved outside the invention (case B) 20 min at 528 ° C ± 2 ° C and then undergoes the same completion as in case A described above. In this case of alloy: T M = 505.5 ° C.
The structure of the alloy is recrystallized with fine and equiaxed grains (average size: 20 µm).
Les propriétés obtenues dans les deux cas dans les sens Long (L), Travers-Long (TL) et à 60° de la direction de laminage (60°/L) sont reportées dans le Tableau I.
On notera que le traitement selon l'invention apporte une amélioration très forte de la résistance à la CST dans le plan de laminage tout en conservant par ailleurs de bons niveaux de propriétés mécaniques.The properties obtained in the two cases in the Long (L), Travers-Long (TL) and 60 ° directions of the rolling direction (60 ° / L) are reported in Table I.
It will be noted that the treatment according to the invention provides a very strong improvement in the resistance to CST in the rolling plane while at the same time retaining good levels of mechanical properties.
Les résultats de propagation de fissures fournis par la figure 5 confirment le bon niveau des propriétés de fatigue de l'alliage traité selon l'invention, qui sont supérieures à celles de l'alliage de référence : 2024.The crack propagation results provided by FIG. 5 confirm the good level of fatigue properties of the alloy treated according to the invention, which are superior to those of the reference alloy: 2024.
Un alliage 2091 de composition : 2,2 % Li - 2,3 % Cu - 1,6 % Mg - Zr 0,10 % - Fe 0,04 % - Si 0,03 %, reste aluminium, est coulé en lingot de section 100 × 300 mm², homogénéisé 24h à 527°C, scalpé, laminé à chaud entre 470 et 380°C jusqu'à 3,6 mm. Une partie des tôles (repérées C) est alors maintenue à chaud selon l'invention: 24 h à 415°C, refroidissement par trempe à l'eau froide.
Tôles D : elles sont maintenues à chaud hors l'invention : 24 h 415°C avec un refroidissement de 8°C/h entre 415 et 100°C.A 2091 alloy with a composition: 2.2% Li - 2.3% Cu - 1.6% Mg - Zr 0.10% - Fe 0.04% - If 0.03%, remains aluminum, is cast in ingot of section 100 × 300 mm², homogenized 24h at 527 ° C, scalped, hot rolled between 470 and 380 ° C up to 3.6 mm. Part of the sheets (marked C) is then kept hot according to the invention: 24 hours at 415 ° C., cooling by quenching with cold water.
D sheets: they are kept hot outside the invention: 24 h 415 ° C with cooling of 8 ° C / h between 415 and 100 ° C.
Les deux types de tôles sont alors laminés à froid jusqu'à 1,6 mm. Les tôles sont mises en solution selon l'invention 20 min à 510°C, trempées à l'eau froide, défripées et tractionnées, puis revenues 12h à 135°C.
Dans ce cas TM= 511,6°C.
Les propriétés de corrosion sous contrainte et de résistance mécanique mesurées sont reportées au Tableau II.The two types of sheet are then cold rolled up to 1.6 mm. The sheets are dissolved in accordance with the invention 20 min at 510 ° C, quenched in cold water, de-plumped and pulled, then returned 12 h at 135 ° C.
In this case T M = 511.6 ° C.
The stress corrosion and mechanical strength properties measured are given in Table II.
Un alliage 2091 de composition (en poids) 2,0% Li - 1,8% Cu - 1,4% Mg - 0,12% Zr - 0,06% Fe - 0,04% Si est coulé en billettes Ø50 mm (réchauffage par induction; filage à 430°C).
Cette barre est usinée à longueurs de 500 mm; ces longueurs ont été réchauffées et matricées en plusieurs passes entre 490 et 400°C. Avant la dernière passe de matriçage, les pièces sont maintenues à chaud selon l'invention 6h à 450°C et déformées à cette température. Elles subissent ensuite un refroidissement dont la vitesse est supérieure à 100°C/h jusqu'à 100°C selon l'invention.
Les pièces sont alors mises en solution à 503°C ± 2°C pendant 4 heures selon l'invention, trempées à l'eau froide et revenues 24h à 190°C (dans ce cas TM= 506,3°C). Ces pièces (voir fig. 6) sont caractérisées en traction et en corrosion sous tension.
Les éprouvettes de traction (sites A,B et C) sont prélevées en dehors des intersections de nervures. Par contre, les éprouvettes de corrosion sous contraintes recoupent les montées de nervures (site D).
Les résultats sont reportés au Tableau III.A 2091 alloy of composition (by weight) 2.0% Li - 1.8% Cu - 1.4% Mg - 0.12% Zr - 0.06% Fe - 0.04% Si is cast in Ø50 mm billets (induction heating; spinning at 430 ° C).
This bar is machined to lengths of 500 mm; these lengths were reheated and stamped in several passes between 490 and 400 ° C. Before the last stamping pass, the parts are kept hot according to the invention for 6 hours at 450 ° C. and deformed at this temperature. They then undergo cooling, the speed of which is greater than 100 ° C./h up to 100 ° C. according to the invention.
The parts are then dissolved at 503 ° C ± 2 ° C for 4 hours according to the invention, soaked in cold water and returned 24 hours to 190 ° C (in this case T M = 506.3 ° C). These parts (see fig. 6) are characterized in tension and stress corrosion.
The tensile test pieces (sites A, B and C) are taken outside the intersections of the ribs. On the other hand, the corrosion corrosion test specimens cut across the ribs (site D).
The results are reported in Table III.
Un alliage de composition (en poids): 2,5% Li - 1,2% Cu - 1,0% Mg 0,06% Zr - 1,5% Zn - 0,06% Fe - 0,04% Si est coulé en plateau de section 300 × 100 mm², homogénéisé 24 heures à 535°C (avec montée en température d'homogénéisation à 25°C/h à partir de 500°C). Il est ensuite scalpé, réchauffé à 490°C, laminé à chaud entre 480 et 300°C jusqu'à 3,6 mm. Le produit brut de laminage à chaud ainsi obtenu est alors maintenu à chaud 1 heure à 450°C, refroidi par trempe à l'eau froide et laminé de 3,6 à 1,2 mm à froid.
Les tôles ainsi obtenues sont mises en solution en four à bain de sel 20 min à 485°C, trempées à l'eau froide, tractionnées de 1,5 % et revenues 12h à 190°C (dans ce cas TM= 512,7°C).
La structure obtenue est recristallisée (voir fig. 7).
Les propriétés obtenues sont reportées au tableau IV.
The sheets thus obtained are dissolved in an oven in a salt bath for 20 min at 485 ° C., quenched in cold water, drawn by 1.5% and returned 12 h at 190 ° C. (in this case T M = 512, 7 ° C).
The structure obtained is recrystallized (see fig. 7).
The properties obtained are given in Table IV.
Claims (15)
TM(°C)= 474 + 18,2 %Li - 2 %Cu(%Cu-1,7) + %Mg(3,6 %Li+4,3 %Cu-17,6) - 3% Zn
et se terminant à la température de fusion commençante de l'alliage.1. Aluminum alloy product containing 1 to 4.2% (by weight) Li, up to 5.5% Cu, up to 7% Mg, up to 15% Zn, up to 0.2% Zr, up to 1% Mn, up to 0.3% Cr, up to 0.2% Nb, up to 0.5% Ni, up to 0.5% Fe, up to '' at 0.5% Si, other elements: up to 0.05% each, remains Al and resistant to corrosion under stress, characterized in that the thermograms obtained by differential enthalpy analysis having a pseudo-bearing, starting at the effective dissolution of the product, which is less than or equal to:
T M (° C) = 474 + 18.2% Li - 2% Cu (% Cu-1.7) +% Mg (3.6% Li + 4.3% Cu-17.6) - 3% Zn
and ending at the starting melting temperature of the alloy.
K.A ou A= % Cu + % Li +
et 2,0 ≦ K ≦ 4,04. Al alloy product containing (by weight%): 1.7 to 2.5% Li - from 0.8 to 3.0% Mg - from 1.0 to 3.5% Cu - up to 2% Zn - from 0 to 0.2% Zr and in total 1% of other elements, remains Al and in that it contains intermetallic phases out of solution rich in elements Al, Li, Cu, Mg and where appropriate Zn in the form of coarse particles whose volume fraction (in%) is substantially equal to:
KA or A =% Cu +% Li +
and 2.0 ≦ K ≦ 4.0
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| FR8702719 | 1987-02-18 | ||
| FR8702719A FR2610949B1 (en) | 1987-02-18 | 1987-02-18 | METHOD FOR DESENSITIZING CORDED UNDER TENSION OF LI-CONTAINING AL ALLOYS |
| FR8801005 | 1988-01-20 | ||
| FR888801005A FR2626009B2 (en) | 1987-02-18 | 1988-01-20 | AL ALLOY PRODUCT CONTAINING LI CORROSION RESISTANT UNDER TENSION |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| EP0282421A2 true EP0282421A2 (en) | 1988-09-14 |
| EP0282421A3 EP0282421A3 (en) | 1989-01-18 |
| EP0282421B1 EP0282421B1 (en) | 1992-05-06 |
Family
ID=26225813
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| EP88420046A Expired - Lifetime EP0282421B1 (en) | 1987-02-18 | 1988-02-16 | Aluminium alloy product containing lithium resistant to corrosion under tension and process for production |
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| Country | Link |
|---|---|
| US (1) | US4955413A (en) |
| EP (1) | EP0282421B1 (en) |
| JP (1) | JPS63266037A (en) |
| CA (1) | CA1333232C (en) |
| DE (1) | DE3870678D1 (en) |
| ES (1) | ES2032591T3 (en) |
| FR (1) | FR2626009B2 (en) |
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| US5374321A (en) * | 1989-11-28 | 1994-12-20 | Alcan International Limited | Cold rolling for aluminum-lithium alloys |
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| CN104674090A (en) | 2007-12-04 | 2015-06-03 | 美铝公司 | Improved aluminum-copper-lithium alloys |
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| EP0124286A1 (en) * | 1983-03-31 | 1984-11-07 | Alcan International Limited | Aluminium alloys |
| EP0157711A1 (en) * | 1984-03-15 | 1985-10-09 | Pechiney Rhenalu | Process for the manufacture of objects from Al-Li-Mg-Cu alloys with high ductibility and isotropy properties |
| EP0157600A2 (en) * | 1984-03-29 | 1985-10-09 | Aluminum Company Of America | Aluminum lithium alloys |
| EP0158571A1 (en) * | 1984-03-15 | 1985-10-16 | Cegedur Societe De Transformation De L'aluminium Pechiney | Al-Cu-Li-Mg alloys with a very high specific mechanical resistance |
| EP0158769A1 (en) * | 1984-02-29 | 1985-10-23 | Allied Corporation | Low density aluminum alloys |
| EP0158761A1 (en) * | 1983-07-26 | 1985-10-23 | Giorgio Targa | Rope-making machine |
| EP0208631A1 (en) * | 1985-06-28 | 1987-01-14 | Cegedur Societe De Transformation De L'aluminium Pechiney | Aluminium alloys with a high lithium and silicon content, and process for their manufacture |
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| DE3365549D1 (en) * | 1982-03-31 | 1986-10-02 | Alcan Int Ltd | Heat treatment of aluminium alloys |
| US4797165A (en) * | 1984-03-29 | 1989-01-10 | Aluminum Company Of America | Aluminum-lithium alloys having improved corrosion resistance and method |
| JPS61133358A (en) * | 1984-11-30 | 1986-06-20 | Inoue Japax Res Inc | High strength and high tension aluminum alloy |
| JPS61166938A (en) * | 1985-01-16 | 1986-07-28 | Kobe Steel Ltd | Al-li alloy for expansion and its production |
-
1988
- 1988-01-20 FR FR888801005A patent/FR2626009B2/en not_active Expired - Lifetime
- 1988-02-16 ES ES198888420046T patent/ES2032591T3/en not_active Expired - Lifetime
- 1988-02-16 DE DE8888420046T patent/DE3870678D1/en not_active Expired - Fee Related
- 1988-02-16 EP EP88420046A patent/EP0282421B1/en not_active Expired - Lifetime
- 1988-02-17 JP JP63034939A patent/JPS63266037A/en active Pending
- 1988-02-17 US US07/156,595 patent/US4955413A/en not_active Expired - Fee Related
- 1988-02-17 CA CA000559131A patent/CA1333232C/en not_active Expired - Fee Related
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|---|---|---|---|---|
| EP0124286A1 (en) * | 1983-03-31 | 1984-11-07 | Alcan International Limited | Aluminium alloys |
| EP0158761A1 (en) * | 1983-07-26 | 1985-10-23 | Giorgio Targa | Rope-making machine |
| EP0158769A1 (en) * | 1984-02-29 | 1985-10-23 | Allied Corporation | Low density aluminum alloys |
| EP0157711A1 (en) * | 1984-03-15 | 1985-10-09 | Pechiney Rhenalu | Process for the manufacture of objects from Al-Li-Mg-Cu alloys with high ductibility and isotropy properties |
| EP0158571A1 (en) * | 1984-03-15 | 1985-10-16 | Cegedur Societe De Transformation De L'aluminium Pechiney | Al-Cu-Li-Mg alloys with a very high specific mechanical resistance |
| EP0157600A2 (en) * | 1984-03-29 | 1985-10-09 | Aluminum Company Of America | Aluminum lithium alloys |
| EP0208631A1 (en) * | 1985-06-28 | 1987-01-14 | Cegedur Societe De Transformation De L'aluminium Pechiney | Aluminium alloys with a high lithium and silicon content, and process for their manufacture |
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| CHEMICAL ABSTRACTS, Vol. 100, No. 24, 11 juin 1984, page 272, Ref. No. 196289b; Columbus, Ohio, US; E.S. BALMUTH: "Particle size determination in an A1-3 Li alloy using DSC", & Scr. Metall. 1984, 18(4), 301-4, whole Abstract. * |
| Proceedings of the 3rd International Aluminium-Lithium Conference, Oxford, 8-11 juillet 1985, pages 37-46; The Inst. of Metals, London, GB, P. MEYER et al.: "Production of aluminium-lithium alloy with high specific properties". * |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5374321A (en) * | 1989-11-28 | 1994-12-20 | Alcan International Limited | Cold rolling for aluminum-lithium alloys |
| CN112908953A (en) * | 2021-02-03 | 2021-06-04 | 百色市彩虹铝业有限公司 | 5G base station chip heat dissipation plate and manufacturing method |
| CN112908953B (en) * | 2021-02-03 | 2022-11-01 | 百色市彩虹铝业有限公司 | 5G base station chip heat dissipation plate and manufacturing method |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS63266037A (en) | 1988-11-02 |
| EP0282421B1 (en) | 1992-05-06 |
| US4955413A (en) | 1990-09-11 |
| CA1333232C (en) | 1994-11-29 |
| EP0282421A3 (en) | 1989-01-18 |
| FR2626009A2 (en) | 1989-07-21 |
| ES2032591T3 (en) | 1993-02-16 |
| DE3870678D1 (en) | 1992-06-11 |
| FR2626009B2 (en) | 1992-05-29 |
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