EP2697406B1 - Aluminium-copper-magnesium alloys that perform well at high temperature - Google Patents

Description

Field of the invention

The invention relates to aluminum-copper-magnesium alloy products, more particularly, such products, their methods of manufacture and use, intended to be implemented at high temperature.

State of the art

• Cu:1,9-2,7 Mg:1,3-1,8 Fe:0,9-1,3, Ni:0,9-1,2 Si:0,10-0,25 Ti:0,04-0,10 qui a été utilisé pour la fabrication du Concorde.

Le brevet FR 2279852 de CEGEDUR PECHINEY propose un alliage à teneur réduite en fer et nickel de composition suivante (% en poids):

• Cu:1,8-3 Mg: 1,2-2,7 Si<0,3 Fe:0,1-0,4 Ni + Co: 0,1 - 0,4 (Ni + Co)/Fe: 0,9 - 1,3

Certain aluminum alloys are commonly used for applications in which they have a high temperature of use, typically between 100 and 200 ° C, for example as structural part or means of attachment near motor in the automotive industry or aerospace or structural part in supersonic aircraft.
These alloys require good mechanical performance at high temperature. The good mechanical performance at high temperature means in particular on the one hand the thermal stability, that is to say that the mechanical properties measured at room temperature are stable after aging for a long time at the temperature of use, and of on the other hand the hot performance that is to say that the mechanical properties measured at high temperature (static mechanical properties, creep resistance) are high. Among the alloys known for this type of application, mention may be made of the AA2618 alloy which comprises (% by weight):

• Cu: 1.9-2.7 Mg: 1.3-1.8 Fe: 0.9-1.3, Ni: 0.9-1.2 Si: 0.10-0.25 Ti: 0, 04-0,10 which was used for the manufacture of the Concorde.

The patent FR 2279852 of CEGEDUR PECHINEY proposes an alloy with a reduced content of iron and nickel of the following composition (% by weight):

• Cu: 1.8-3 Mg: 1.2-2.7 If <0.3 Fe: 0.1-0.4 Ni + Co: 0.1 - 0.4 (Ni + Co) / Fe: 0 , 9 - 1.3

• Cu: 2,0 - 3,0 Mg: 1,5 - 2,1 Mn: 0,3 - 0,7
• Fe<0,3 Ni<0,3 Ag<1,0 Zr<0,15 Ti<0,15
• avec Si tel que: 0,3 < Si + 0,4Ag < 0,6
• autres éléments < 0,05 chacun et < 0,15 au total.

Le brevet RU2210614C1 décrit un alliage de composition (en % en poids)
Cu: 3,0 - 4,2 Mg: 1,0 - 2,2 Mn: 0,1 - 0,8 Zr : 0,03 - 0,2 Ti : 0,012 - 0,1, V : 0,001 - 0,15 au moins un élément parmi Ni : 0,001 - 0,25 et Co : 0,001 - 0,25, reste aluminium.
L'alliage AA2219 de composition (en % en poids) Cu : 5,8 - 6,8 Mn : 0,20 - 0,40 Ti : 0,02 - 0,10, Zr: 0,10 - 0,25 V: 0,05 - 0,15 Mg < 0,02 est également connu pour des applications à haute température.
Ces alliages présentent cependant des propriétés mécaniques insuffisantes pour certaines applications et posent également des problèmes de recyclage en raison en particulier de la teneur élevée en fer et/ou silicium et/ou nickel et/ou cobalt et/ou vanadium.The alloy may also contain Zr, Mn, Cr, V or Mo at levels less than 0.4%, and optionally Cd, In, Sn or Be at less than 0.2% each, Zn less than 8% or Ag less than 1%. With this alloy, a significant improvement in the stress concentration factor K1c representative of the resistance to crack propagation is obtained.
The patent application EP 0 756 017 A1 (Pechiney Rhenalu ) relates to an aluminum alloy with a high creep resistance of composition (% by weight):

• Cu: 2.0 - 3.0 Mg: 1.5 - 2.1 Mn: 0.3 - 0.7
• Fe <0.3 Ni <0.3 Ag <1.0 Zr <0.15 Ti <0.15
• with Si such that: 0.3 <Si + 0.4Ag <0.6
• other elements <0.05 each and <0.15 in total.

The patent RU2210614C1 discloses an alloy of composition (in% by weight)
Cu: 3.0 - 4.2 Mg: 1.0 - 2.2 Mn: 0.1 - 0.8 Zr: 0.03 - 0.2 Ti: 0.012 - 0.1, V: 0.001 - 0, At least one of Ni: 0.001 - 0.25 and Co: 0.001 - 0.25, remains aluminum.
Composition AA2219 alloy (in% by weight) Cu: 5.8 - 6.8 Mn: 0.20 - 0.40 Ti: 0.02 - 0.10, Zr: 0.10 - 0.25 V : 0.05 - 0.15 Mg <0.02 is also known for high temperature applications.
These alloys, however, have insufficient mechanical properties for certain applications and also pose recycling problems due in particular to the high content of iron and / or silicon and / or nickel and / or cobalt and / or vanadium.

Al-Cu-Mg alloys are also known.
The patent US 3,826,688 teaches a composition alloy (in% by weight), Cu: 2.9 - 3.7, Mg: 1.3 - 1.7 and Mn: 0.1 - 0.4.
The patent US 5,593,516 teaches an alloy of composition (in% by weight) Cu: 2.5 - 5.5, Mg: 0.1 - 2.3 in the limit of their solubility that is to say such that Cu is at most equal at Cu _max = -0.91 (Mg) + 5.59.
The patent application EP 0 038 605 A1 teaches a composition alloy (in% by weight), Cu: 3.8 - 4.4, Mg: 1.2 - 1.8 and Mn: 0.3 - 0.9, maximum 0.12 Si, 0 , Fe, 0.25 Zn, 0.15 Ti and 0.10 Cr.
The patent US 6,444,058 teaches a high purity alloy composition Al-Mg-Cu for which the effective values of Cu and Mg are defined, in particular by Cu _target = Cu _eff + 0.74 (Mn - 0.2) + 2.28 (Fe - 0.005), and teaches a composition domain in the Cu _eff : Mg _eff diagram in which the maximum value of Mg _eff is of the order of 1.4 % in weight.

There is a need for aluminum alloy products having good mechanical performance at high temperatures, typically at 150 ° C, and being easy to manufacture and recycle.

Object of the invention

A first subject of the invention is a wrought product made of aluminum alloy of composition, in% by weight,
Cu _Corr : 2.6 - 3.7
Mg _corr : 1.5 - 2.6
Mn: 0.2 - 0.5
Zr: ≤ 0.16
Ti: 0.01 - 0.15
Cr ≤ 0.25
If ≤ 0.2
Fe ≤ 0.2
other elements <0.05
rest aluminum
with Cu _corr > - 0.9 ( _Corr. Mg) + 4.3 and _Corr Cu <- 0.9 ( _Corr. Mg) + 5.0
wherein Cu _corr = Cu - 0.74 (Mn - 0.2) - 2.28 Fe and
Mg _corr = Mg - 1.73 (Si - 0.05) for Si ≥ 0.05 and Mg _corr = Mg for Si <0.05.

• l'élaboration d'un bain de métal liquide de façon à obtenir un alliage d'aluminium de composition selon l'invention,
• la coulée dudit alliage typiquement sous forme de plaque de laminage, de billette de filage, d'ébauche de barre ou fil,
• optionnellement l'homogénéisation du produit ainsi coulé de façon à atteindre une température comprise entre 450°C et 520° C,
• la déformation avant mise en solution du produit ainsi obtenu,
• la mise en solution du produit ainsi déformé par un traitement thermique permettant d'atteindre une température comprise entre 490 et 520 °C et de préférence entre 500 et 510 °C pendant 15 min à 8 h, puis la trempe,
• optionnellement la déformation à froid du produit ainsi mis en solution et trempé,
• le revenu dans lequel le produit ainsi obtenu atteint une température comprise entre 160 et 210°C et de préférence entre 175 et 195°C pendant 5 à 100 heures et de préférence de 10 à 50h

Another subject of the invention is a method of manufacturing a wrought product according to the invention comprising, successively,

• developing a bath of liquid metal so as to obtain an aluminum alloy of composition according to the invention,
• casting said alloy typically in the form of rolling plate, spinning billet, bar blank or wire,
• optionally homogenizing the product thus cast so as to reach a temperature of between 450 ° C. and 520 ° C.,
• the deformation before dissolution of the product thus obtained,
• dissolving the product thus deformed by a heat treatment making it possible to reach a temperature of between 490 and 520 ° C. and preferably between 500 and 510 ° C. for 15 minutes to 8 hours, and then quenching,
• optionally cold deformation of the product thus dissolved and quenched,
• the yield in which the product thus obtained reaches a temperature of between 160 and 210 ° C. and preferably between 175 and 195 ° C. for 5 to 100 hours and preferably from 10 to 50 hours.

Yet another object of the invention is the use of a wrought product according to the invention in an application in which said product is maintained at temperatures of 100 ° C. to 200 ° C. for a significant period of at least 200 hours. hours.

Description of figures

• Figure 1 : Representation of the composition domain according to the invention in the plane Mg _corr : Cu _corr .
• Figure 2 : Evolution of the elastic limit R _p0,2 with the aging time for the rolled products of Example 1; Fig 2a aging at 150 ° C, Fig 2b aging at 200 ° C, Fig 2c aging at 250 ° C.
• Figure 3 : Evolution of the elastic limit R _p0,2 with the aging time at 150 ° C for the spun products of Example 2; Fig 3a : state T6, Fig 3b : T8 state.

Description of the invention

Unless stated otherwise, all the information concerning the chemical composition of the alloys is expressed as a percentage by weight based on the total weight of the alloy. The expression 1.4 Cu or 1.4 (Cu) means that the copper content expressed in% by weight is multiplied by 1.4. Alloys are designated in accordance with the regulations of the The Aluminum Association, known to those skilled in the art. The definitions of the metallurgical states are given in the European standard EN 515.
The static mechanical characteristics in tension, in other words the tensile strength R _m , the conventional yield stress at 0.2% elongation R _p0.2 and the elongation at break A%, are determined by a tensile test according to standard NF EN ISO 6892-1, the sampling and the direction of the test being defined by the EN 485-1 standard. The hot tensile tests are carried out according to standard NF EN 10002-5. Creep tests are performed according to ASTM E139-06.

Unless otherwise specified, the definitions of EN 12258 apply.

$${\mathrm{Mg}}_{\mathrm{corr}}=\mathrm{Mg}-1,73\left(\mathrm{Si}-0,05\right)$$

pour Si au moins égal à 0,05% en poids et Mg_corr = Mg pour une teneur en Si inférieure à 0,05 % en poids.
On peut remarquer que si la teneur en Mn est inférieure à 0,2 % en poids, on calcule $${\mathrm{Cu}}_{\mathrm{corr}}=\mathrm{Cu}-2,28\mathrm{Fe}\mathrm{.}$$

The present inventors have found that, surprisingly, there is a compositional range of Al-Cu-Mg alloys containing Mn which makes it possible to obtain particularly high performance wrought products at high temperature.
The composition of the wrought products of the invention is defined according to the content of iron, manganese and silicon.
Corrected Cu and Mg contents, called Cu _Corr and Mg _corr corresponding to the contents of these elements which are not trapped by intermetallic compounds containing iron, manganese or silicon, are defined. This correction is important in defining the Cu and Mg composition domain of the invention because the iron and manganese containing intermetallic compounds formed with the copper and the intermetallic compounds formed with the silicon-containing magnesium generally can not be processed. solution. Cu _corr and Mg _corr thus correspond to the Cu and Mg contents available after solution dissolution for the formation during the recovery of the nanometric phases contributing to hardening.
The corrected grades are obtained using the following equations: $${\mathrm{Cu}}_{\mathrm{corr}}=\mathrm{Cu}-0,74\left(\mathrm{mn}-0,2\right)-2,28\mathrm{Fe}$$

$${\mathrm{mg}}_{\mathrm{corr}}=\mathrm{mg}-1,73\left(\mathrm{Yes}-0,05\right)$$

for Si at least equal to 0.05% by weight and Mg _corr = Mg for a Si content of less than 0.05% by weight.
It can be noted that if the Mn content is less than 0.2% by weight, it is calculated $${\mathrm{Cu}}_{\mathrm{corr}}=\mathrm{Cu}-2,28\mathrm{Fe}\mathrm{.}$$

$${\mathrm{Cu}}_{\mathrm{corr}}<-0,9\left({\mathrm{Mg}}_{\mathrm{corr}}\right)+5,0$$

La teneur en magnésium est telle que Mg_corr soit compris entre 1,5 et 2,6 % en poids et de préférence entre 1,6 et 2,4 % en poids.
Dans un mode de réalisation avantageux de l'invention, Mg_corr est au moins égal à 1,8 % en poids et de préférence au moins égal à 1,9 en % en poids. Ce mode de réalisation est particulièrement avantageux pour les produits à l'état T6.To obtain the desired effect on the mechanical performance at high temperature, the copper and magnesium contents thus corrected must obey the following inequalities: $${\mathrm{Cu}}_{\mathrm{corr}}>-0,9\left({\mathrm{mg}}_{\mathrm{corr}}\right)+4,3\left({\mathrm{preferably\; Cu}}_{\mathrm{corr}}>-0,9\left({\mathrm{mg}}_{\mathrm{corr}}\right)+4,5\right)$$

$${\mathrm{Cu}}_{\mathrm{corr}}<-0,9\left({\mathrm{mg}}_{\mathrm{corr}}\right)+5,0$$

The magnesium content is such that Mg _corr is between 1.5 and 2.6% by weight and preferably between 1.6 and 2.4% by weight.
In an advantageous embodiment of the invention, Mg _corr is at least 1.8% by weight and preferably at least 1.9% by weight. This embodiment is particularly advantageous for products in the T6 state.

The copper content is such that Cu _corr is between 2.6 and 3.7% by weight. Advantageously Cu _corr is at least 2.7% by weight and preferably at least 2.8% by weight.
From the equations indicated and the conditions required for Mg _corr and Cu _corr we can establish that the maximum copper content is 4.33% by weight, corresponding to a corrected content Cu _cor = 3.65% by weight, obtained for an iron content of 0.2% by weight, a manganese content of 0.5% by weight and a Mg _corr corrected content of 1.5% by weight, corresponding for example to a Mg content of 1.5%. by weight and a silicon content of 0.05% by weight. The minimum copper content is 2.6% by weight, corresponding to a corrected content Cu _corr = 2.6% by weight obtained for an iron content of 0% by weight and a manganese content of 0.2% by weight.
The maximum magnesium content is 2.86% by weight corresponding to a Mg content _corr of 2.6% by weight, obtained for an Si content of 0.2% by weight. The minimum magnesium content is 1.5% by weight, obtained for a Si content of 0% by weight. One can also note that for a _corr Mg content of at least 1.9% by weight, and a maximum content of iron and silicon of 0.08 wt%, the maximum copper content is 3.69% by weight, obtained for a manganese content of 0.5% by weight and corresponding to a corrected Cu _corr content of 3.29% by weight.

The corresponding domain in the plane Mg _corr : Cu _corr is represented on the Figure 1 .

Independently of the values Mg _corr and Cu _corr, an advantageous range of composition of the products according to the invention has a magnesium content of between 1.6 and 2.2% by weight and preferably between 1.8 and 2.1% by weight. and / or a copper content of between 2.8 and 3.7% by weight and preferably between 2.9 and 3.4% by weight.

The products according to the invention contain 0.2 to 0.5% by weight of manganese, which contributes in particular to the control of the granular structure. The present inventors have found that the simultaneous addition of manganese and zirconium is advantageous for further improving the control of the granular structure. Advantageously, the Zr content is at least 0.07% by weight and preferably at least 0.08% by weight. In an advantageous embodiment, the products according to the invention contain 0.09 to 0.15% by weight of zirconium and 0.25 to 0.45% by weight of manganese.
The chromium content is at most 0.25% by weight. In one embodiment of the invention, the chromium content is between 0.05 and 0.25% by weight and can contribute in particular to the control of the granular structure. However, the presence of chromium can cause problems of recycling and sensitivity to quenching, especially for products whose thickness is at least 50 mm. In another embodiment, the chromium content is less than 0.05% by weight.
The titanium content is between 0.01 and 0.15% by weight. The addition of titanium contributes in particular to the refining of the grains during casting. In one embodiment, it is preferred to limit the addition of titanium to a maximum value of 0.05% by weight. However, a larger ripening may be useful. Thus, in another embodiment of the invention, the titanium content is between 0.07 and 0.14% by weight.
The iron and silicon contents are at most 0.2% by weight each. In an advantageous embodiment of the invention, the iron and / or silicon contents are at most 0.1% by weight and preferably 0.08% by weight. The equations for calculating _corr Cu and Mg _corr take account of variations of Fe and Si and to achieve the same value of Cu _corr more copper is added when the iron content increases.
The content of the other elements is less than 0.05% by weight. The rest is aluminum.

The wrought products according to the invention are typically sheets, profiles, bars or wires, but can also be screws, bolts or rivets.

The method of manufacturing the products according to the invention comprises the successive stages of elaboration of the alloy, casting, optionally homogenization, deformation, dissolution, tempering, optionally cold deformation and tempering.

In a first step, a bath of liquid metal is produced so as to obtain an aluminum alloy of composition according to the invention. The liquid metal bath is then typically cast in the form of a rolling plate, spinning billet, bar blank or wire.
Advantageously, the product thus cast is then homogenized so as to reach a temperature of between 450 ° C. and 520 ° C. and preferably between 500 ° C. and 510 ° C. for a period of between 5 and 60 hours. The homogenization treatment can be carried out in one or more stages.
The product is then typically deformed by rolling, spinning and / or drawing and / or drawing and / or coining.
The product thus deformed is then dissolved in a heat treatment to reach a temperature of between 490 and 520 ° C and preferably between 500 and 510 ° C for 15 min to 8 h, and then quenched.
The quality of dissolution can be evaluated by calorimetry and / or optical microscopy. The objective being that Cu and Mg are in solid solution with the exception of Cu and bound Mg in the intermetallic compounds containing manganese of iron and / or silicon.
The product can then optionally undergo a cold deformation.
Finally, an income is achieved in which the product reaches a temperature between 160 and 210 ° C and preferably between 175 and 195 ° C for 5 to 100 hours and preferably 10 to 50h. The income can be achieved in one or more levels. Preferably, the income conditions are determined so that the mechanical resistance Rp _0.2 is maximum ("peak" income).

There are two main embodiments of the method according to the invention depending on the form of the wrought products. A first embodiment of the method according to the invention allows the manufacture of sheets or profiles. A second embodiment of the method according to the invention allows the manufacture of son or bars, such as in particular blanks for machining, blanks forging, blanks bolts, rivet threads, blanks screws and bolts, screws and rivets.

The first embodiment of the process according to the invention comprises the successive stages of elaboration of the alloy, cast in the form of a plate or billet, optionally homogenization, hot deformation, dissolution, tempering, optionally cold deformation and tempering. .
In the first embodiment of the process according to the invention, the liquid metal bath is cast in the form of a rolling plate or a spinning billet.
The optionally homogenized rolling plate or spinning billet is then hot deformed by rolling or spinning. The hot deformation of the first embodiment is performed so as to maintain a temperature of at least 300 ° C. Advantageously, a temperature of at least 350 ° C. and preferably at least 380 ° C. is maintained during the hot deformation.
In the first embodiment of the process according to the invention, no significant cold deformation is carried out, in particular by cold rolling, between the hot deformation and the dissolution. Indeed, such a cold deformation step would lead to a recrystallized structure that is undesirable in the context of the invention for wrought products in the form of sheets or profiles. Significant cold deformation is typically a deformation of at least about 5%.
The sheet or the profile thus obtained is then put in solution by a heat treatment making it possible to reach a temperature of between 490 and 520 ° C. and preferably between 500 and 510 ° C. for 15 minutes to 8 hours, and then quenched typically with the water.

The combination of the chosen composition, in particular the manganese content, and the transformation range, in particular the hot deformation temperature and the absence of significant cold deformation before being dissolved, makes it possible to obtain sheets or profiles having a substantially non-recrystallized granular structure. By substantially non-recrystallized granular structure means a non-recrystallized granular structure content at mid-thickness greater than 70% and preferably greater than 85%.

The sheet or the profile obtained can then optionally undergo a cold deformation. Advantageously, the cold deformation is a controlled traction with a permanent elongation of 2 to 5% to improve the mechanical strength and to obtain a T8 state after income.
In the absence of cold deformation or in the presence of a low cold deformation does not improve the mechanical characteristics, after income a product is obtained in the T6 state.

The sheets and profiles obtained according to the first embodiment of the method of the invention have the advantage of having a high mechanical strength and good performance at high temperature. Thus, the sheets and profiles according to the invention preferably have, in the longitudinal direction T8, a yield strength R _p0.2 of at least 440 MPa, preferably at least 450 MPa and, preferably, at least 450 MPa. at least 455 MPa. For the profiles according to the invention in the T8 state, a yield strength R _p0.2 of at least 470 MPa can advantageously be obtained in the longitudinal direction. After aging at 150 ° C. for 2000 h, the reduction of the elastic limit of the sheets and profiles according to the invention in the T8 state in the longitudinal direction is advantageously less than 12%, preferably less than 10% and, preferably, less than 8%.
The profiles according to the invention advantageously have, in the T8 state, a yield strength measured at 150 ° C. in the longitudinal direction of at least 370 MPa and preferably at least 380 MPa.
In the T6 state, the sheets or profiles made in the embodiment in which the Mg content is such that Mg _corr is at least 1.8% by weight advantageously have a yield strength measured at 150 ° C. in the longitudinal direction of at least 340 MPa and a decrease in yield strength after 2000h aging at 150 ° C less than 5%.

The second embodiment of the method according to the invention comprises the successive stages of elaboration of the alloy, cast in the form of wire blank or bar, optionally homogenization, hot deformation and / or cold by spinning and / or stretching and / or drawing and optionally by subsequent striking of the wire or bar obtained to obtain screws, bolts or rivets, dissolution, quenching and tempering.
In the second embodiment of the process according to the invention the liquid metal bath is cast as a blank of wire or bar, preferably on a casting wheel, typically with the continuous casting process known as " Properzi ". The wire blank or bar may also be a spinning billet.
The blank wire or bar is then deformed hot and / or cold by spinning and / or drawing and / or drawing. In particular, if the wire blank or bar is a spinning billet, it will be hot-spun before being cold-formed by drawing and / or drawing, whereas if the wire blank or bar has been obtained by continuous casting and hot deformation at the outlet of the casting wheel, it will only be necessary to deform it cold.
Optionally, the wire or bar obtained can be struck at this point to obtain screws, bolts or rivets.
The product thus obtained is then put in solution by a heat treatment making it possible to reach a temperature of between 490 and 520 ° C. and preferably between 500 and 510 ° C. for 15 minutes to 8 hours, and then typically quenched with water. .

The combination of the chosen composition, in particular the manganese content, and the deformation achieved makes it possible to obtain, in the second embodiment of the process according to the invention, products having a substantially recrystallized granular structure. By essentially recrystallized structure is meant a recrystallization rate of at least 80% and preferably a fine grain structure and homogeneous size.
The product obtained can then optionally undergo a cold deformation.
However, in the manufacture of certain products, such as in particular bolts, screws and rivets, it is difficult to perform a cold deformation after dissolution and quenching. Advantageously, the product is not subjected to cold deformation after dissolution and quenching, and after recovery a T6 state is obtained. A particularly alloy advantageous for the T6 state has an Mg content such that Mg _corr is at least equal to 1.8% by weight.
On the other hand, the manufacture of products such as wire, bolt, rivet, screw, in the T8 state and having a substantially recrystallized alloy granular structure according to the invention is advantageous.
The products obtained according to the second embodiment of the process of the invention advantageously have in the T8 state in the longitudinal direction a yield strength R _p0.2 of at least 460 MPa, preferably at least 480 MPa. and after aging at 150 ° C. for 2000 h, a decrease in the yield strength in the longitudinal direction of less than 10%, preferably less than 8%.
The products according to the invention are particularly useful for applications in which the products are maintained at temperatures of 100 ° C to 200 ° C, typically at about 150 ° C, for a significant period of at least 200 hours and preferably at least 2000 hours.
Thus the products according to the invention are useful for fasteners intended for use in a motor typically for automobiles, such as screws or bolts or rivets. The products according to the invention are also useful for the manufacture of parts of the nacelle and / or aircraft attachment masts. The nacelle designates all the supports and hoods of an engine of a multi-engine aircraft: The products according to the invention are also useful for the manufacture of aircraft wing leading edges. The products according to the invention are also useful for the manufacture of fuselage of supersonic aircraft.

These and other aspects of the invention are explained in more detail with the aid of the following illustrative and nonlimiting examples.

Examples Example 1

In this example 4 alloys were cast in the form of 70x170x27 mm size plates. Alloys A-1 and C-1 have a composition according to the invention.

The composition of the alloys is given in Table 1. Table 1 composition (% by weight) Alloy Yes Fe Cu mn mg Ti Zr Cu _Corr Mg _corr A-1 (Inv.) 0.04 0.05 3.3 0.34 1.9 0.02 0.11 3.1 1.9 C-1 (Inv.) 0.04 0.05 3.7 0.34 1.6 0.02 0.11 3.5 1.6 B-1 (Ref.) 0.04 0.05 4.2 0.34 1.3 0.02 0.11 4.0 1.3 D-1 (Ref.) 0.04 0.05 5.4 0.35 0.3 0.02 0.11 5.2 0.3 Inv. : Inventnion Ref. : Reference

The plates were homogenized at a temperature of between 500 ° C. and 540 ° C., adapted according to the alloy, hot-rolled to a thickness of 15 mm, dissolved at a temperature of between 500 ° C. and 540 ° C, adapted according to the alloy, quenched with water by immersion, traced by 3 to 4% and returned to 190 ° C to reach the peak of elastic limit in tension at the T8 state. Thus the alloy plate A-1 was homogenized in two steps of 10h at 500 ° C and 20h at 509 ° C, the sheet obtained after rolling being dissolved for 2h at 507 ° C and returned for 12 hours at 190 ° C. The alloy plate B-1 was homogenized in two steps of 10h at 500 ° C and 20h at 503 ° C, the sheet obtained after rolling being dissolved in 2h at 500 ° C and returned 8h at 190 ° C. The alloy plate C-1 was homogenized in two steps of 10h at 500 ° C and 20h at 503 ° C, the sheet obtained after rolling being dissolved in 2h at 504 ° C and returned for 12 hours at 190 ° C. The alloy plate D-1 was homogenized in two steps of 10h at 500 ° C and 20h at 536 ° C, the sheet obtained after rolling being dissolved for 2h at 535 ° C and returned 8h at 190 ° C.

The sheets obtained had a substantially non-recrystallized granular structure. The sheets thus obtained were characterized in the longitudinal direction before and after aging at several temperatures and for several durations. The results are shown in Table 2 Table 2 - Mechanical properties obtained at mid-thickness L-direction before and after aging (MPa) Aging temperature (° C) Aging time (h) A-1 C-1 B-1 D-1 R _0.2 rm R _0.2 rm R _0.2 rm R _0.2 rm No aging 456 476 468 485 470 483 385 447 150 500 450 471 471 487 451 488 379 442 150 1000 447 467 462 484 427 472 372 438 150 2000 436 467 440 473 411 463 375 450 150 5000 421 455 424 466 386 449 352 431 200 500 355 398 353 417 312 365 288 375 200 1000 340 405 332 404 295 380 273 360 200 2000 314 380 308 381 264 355 261 352 200 5000 274 360 269 358 221 316 245 333 250 200 305 382 301 374 263 354 262 352 250 400 245 335 235 327 203 300 234 324 250 600 176 284 163 265 145 252 222 314 250 800 150 265 136 246 109 222 215 311

The evolution of the mechanical properties with the aging time for the different temperatures studied are represented on the Figures 2a to 2c . It can be seen that for an aging temperature of 200 ° C., the sheets according to the invention (A-1 and C-1) have, for 2000 h of aging, an elasticity limit improved by more than 15% with respect to the reference sheets. (B-1 and D-1).

Example 2

In this example two alloys were cast in the form of 200 mm diameter billets. These alloys A-2 and C-2 have a composition according to the invention.
The compositions are given in Table 3. Table 3 - composition (% by weight) Alloy Yes Fe Cu mn mg Ti Zr Cu _Corr Mg _corr A-2 (Inv.) 0.06 0.04 3.0 0.33 2.0 0.02 0.10 2.8 2.0 C-2 (Inv.) 0.04 0.04 3.7 0.34 1.6 0.02 0.11 3.5 1.6 Inv. : Invention The billets were homogenized at a temperature of between 500 ° C. and 520 ° C., adapted according to the alloy and spun into cylindrical bars 13 mm in diameter, dissolved at a temperature of between 500 ° C. and 520 ° C. ° C, adapted in function of the alloy, soaked in water. Thus, the alloy billet A-2 was homogenized 24h at 508 ° C. and the bars obtained dissolved for 1 hour at 506 ° C. The alloy billet C-2 was homogenized 24h at 508 ° C. and the bars obtained dissolved for 1 hour at 503 ° C. Some bars were trimmed from 3 to 4% of other bars were not pulled, all the bars finally had a peak income to get a T6 state (untracted, 20h at 190 ° C for A-2 and 16h at 190 ° C for C-2) or T8 (tractionné, 12h at 190 ° C for the two alloys). The profiles obtained had a substantially non-recrystallized granular structure.

For reference, alloy wires 6056 in the T6 state with a diameter of 12 mm and alloy bars 2618 in the T8 state with a diameter of 40 mm were used.
The mechanical properties in the longitudinal direction before and after aging at 150 ° C are given in Table 4. Table 4 - L-axis mechanical properties at mid-diameter Aging time (h) at 150 ° C Alloy State Metallurgical R _p0.2 (MPa) R _m (MPa) Lengthening% 0 2-A T8 514 538 10 0 C-2 T8 476 510 11 0 2618 T8 434 459 8 0 2-A T6 397 478 11 0 C-2 T6 402 492 12 0 6056 T6 378 412 15 1000 2-A T8 480 515 11 1000 C-2 T8 467 507 12 1000 2618 T8 415 447 9 1000 2-A T6 393 471 11 1000 C-2 T6 363 455 13 1000 6056 T6 375 397 13 2000 2-A T8 453 491 4 2000 C-2 T8 447 491 5 2000 2618 T8 402 439 4 2000 2-A T6 399 468 5 2000 C-2 T6 332 429 6 2000 6056 T6 359 384 6

These results are also presented in the Figures 3a and 3b . In the T6 state, the alloy A-2 is particularly thermally stable.

Tensile characterization tests at a temperature of 150 ° C. were also carried out according to standard NF EN 10002-5.
The results are shown in Table 5. Table 5. Characterization of mechanical properties L-direction at 150 ° C Alloy State R _p0.2 (MPa) R _m (MPa) Lengthening% 6056 T6 333 343 16 2-A T6 349 412 18 C-2 T6 338 405 18 2618 T8 357 390 14 2-A T8 398 420 17 C-2 T8 385 413 17

It is found that the products according to the invention have, in particular, a breaking strength significantly higher than that of conventionally used reference products such as alloy 6056 (T6) or alloy 2618 (T8).

Creep tests were carried out according to the ASTM E139-06 standard for a stress of 285 MPa and at a temperature of 150 ° C. In particular, the service life, the deformation after 200h and the stationary creep rate were measured. The results are collated in Table 6. Table 6 L sense Alloy State Life in creep (h) Deformation after 200h (%) Stationary creep rate (s-1) PRT. # 1 PRT. # 2 PRT. # 1 PRT. # 2 PRT. # 1 PRT. # 2 6056 T6 310 393 0.30 0.30 3.3E-09 3.7E-09 2-A T6 377 458 0.47 0.50 6,6E-09 6,7E-09 C-2 T6 487 730 0.51 0.43 6.5E-09 5,5E-09 2618 T8 343 283 0.89 1.41 1,1E-08 1.5E-08 2-A T8 > 827.9 > 779.9 0.25 0.40 1.9E-09 2.8E-09 C-2 T8 > 825.2 > 817.8 0.26 0.26 4,1E-09 3,8E-09 PRT. : test tube

Example 3

In this example a 13 mm diameter C-2 alloy cylindrical bar was obtained by hot spinning from a billet homogenized 24h at 508 ° C. The bar was then stretched cold to obtain a wire of diameter 10; 55 mm. The yarn thus obtained was dissolved for 1 hour at 503 ° C., fractionated by 3 to 4% and then returned for 12 hours at 190 ° C. to obtain a T8 state.

The granular structure of the yarn thus obtained, as observed in particular in the plane TLxTC half thickness, was essentially recrystallized and had a fine and homogeneous grain

The mechanical properties obtained in the longitudinal direction before and after aging at 150 ° C are given in Table 7. Table 7 - Mechanical properties L-direction at mid-diameter of the wire of diameter 10.55 mm Aging time (h) at 150 ° C Alloy State Metallurgical R _p0.2 (MPa) R _m (MPa) Lengthening% 0 C-2 T8 503 522 7.8 1000 C-2 T8 462 494 6.9 2000 C-2 T8 471 508 7.7 Measurement at 150 ° C C-2 T8 397 428

Claims (15)

1. Wrought product selected from the group comprising sheet metal, profile, bar, wire, screw, bolt and rivet, obtained via a method comprising the successive steps of elaborating an alloy, casting, optionally homogenisation, deformation, heat treat, quenching, optionally cold working and ageing, said alloy being an aluminium alloy of composition, in % by weight,
   Cu_wrt: 2.6 - 3.7
   Mg_wrt : 1.5-2.6
   Mn: 0.2 -0.5
   Zr: ≤ 0.16
   Ti: 0.01 - 0.15
   Cr: ≤ 0.25
   Si: ≤ 0.2
   Fe: ≤ 0.2
   other elements < 0.05
   remainder aluminium
   with Cu_wrt > - 0.9(Mg_wrt] + 4.3 and Cu_wrt < - 0.9 (Mg_wrt) + 5.0
   wherein Cu_wrt = Cu - 0.74 (Mn - 0.2) - 2.28 Fe and
   Mg_wrt = Mg - 1.73 (Si - 0.05) for Si ≥ 0.05 and Mg_wrt = Mg pour Si<0.05, CU_wrt and Mg_wrt corresponding to the contents of Cu and Mg which are not trapped by par intermetallic compounds containing iron, manganese or silicon.
2. Wrought product according to claim 1 wherein Mg_wrt is at least equal to 1.8% by weight and preferably at least equal to 1.9 in % by weight.
3. Wrought product according to claim 1 or claim 2 wherein Zr is at least equal to 0.07 in % by weight and preferably at least equal to 0.08 in % by weight.
4. Wrought product according to any one of claims 1 to 3 characterised in that it is sheet metal or a profile of which the granular structure is substantially non-recrystallised.
5. Wrought product according to claim 4 having in state T8 in the longitudinal direction a yield point R_p0.2 of at least 440 MPa and more preferably of at least 450 MPa and having after ageing at 150°C for 2000h, a decrease in the yield point in the longitudinal direction less than 12% and more preferably less than 10%.
6. Wrought product according to claim 4 wherein Mg_wrt is at least equal to 1.8% by weight and having at the T6 state a yield point measured at 150°C in the longitudinal direction of at least 340 MPa and a decrease in the yield point after 2000h of ageing at 150°C less than 5%.
7. Wrought product according to any one of claims 1 to 3 characterised in that it is a wire or a bar or a bolt or a screw or a rivet having a substantially recrystallised granular structure.
8. Wrought product according to claim 7 having at the T8 state in the longitudinal direction a yield point R_p0.2 of at least 460 MPa, more preferably of at least 480 MPa and after ageing at 150°C for 2000h, a decrease in the yield point in the longitudinal direction less than 10% and more preferably less than 8%.
9. Method for manufacturing a wrought product according to one of claims 1 to 8 comprising successively

   - the elaboration of a bath of liquid metal in such a way as to obtain an aluminium alloy of composition according to any one of claims 1 to 3,

   - the casting of said alloy typically in the form of a rolling plate, extrusion billet, bar blank or wire,

   - optionally the homogenisation of the product cast as such in such a way as to reach a temperature between 450°C and 520°C,

   - the deformation before heat treat of the product obtained as such,

   - the heat treat of the product deformed as such by a thermal treatment making it possible to reach a temperature between 490 and 520°C and preferably between 500 and 510°C for 15 min to 8 h, then quenching,

   - optionally the cold working of the product heat treat and quenched as such,

   - the aging wherein the product obtained as such reaches a temperature between 160 and 210°C and preferably between 175 and 195°C for 5 to 100 hours and more preferably from 10 to 50h.
10. Method according to claim 9 wherein

    - said casting of the alloy is done in the form of a rolling plate or extrusion billet,

    - said deformation before heat treat is carried out by rolling or hot extrusion in such a way as to maintain a temperature of at least 300°C, without carrying out any significant cold working.
11. Method according to claim 10 wherein said cold working of the product heat treat and quenched is carried out by a controlled tension with permanent elongation of 2 to 5% in order to obtain after ageing a T8 state.
12. Method according to claim 9 wherein

    - said casting of the alloy is carried out in the form of a blank of wire or bar,

    - said deformation before heat treat is carried out by extrusion and/or drawing and/or hot and/or cold wire drawing in order to obtain a wire or a bar, and optionally by subsequent striking of the wire or of the bar obtained in order to obtain screws, bolts or rivets,

    - there is no cold working of the product heat treat and quenched

    - the final temper after ageing is a T6 state.
13. Use of a wrought product according to any one of claims 1 to 7 in an application wherein said product is maintained at temperatures from 100°C to 200°C for a significant duration of at least 200 hours.
14. Use according to claim 13 wherein said product is a fastener intended to be used in an engine typically for a motor vehicle, such as a screw or a bolt or a rivet.
15. Use according to claim 13 wherein said product is a part of the nacelle and/or of the aircraft attachment mast or of the aircraft wing leading edge or of a supersonic aircraft fuselage.

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