EP0214381B1 - Alliage aluminium-lithium - Google Patents

Alliage aluminium-lithium Download PDF

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Publication number
EP0214381B1
EP0214381B1 EP19860108331 EP86108331A EP0214381B1 EP 0214381 B1 EP0214381 B1 EP 0214381B1 EP 19860108331 EP19860108331 EP 19860108331 EP 86108331 A EP86108331 A EP 86108331A EP 0214381 B1 EP0214381 B1 EP 0214381B1
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EP
European Patent Office
Prior art keywords
max
aging
alloy
article
aluminum
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
EP19860108331
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German (de)
English (en)
Other versions
EP0214381A1 (fr
Inventor
Hari G. Narayanan
R. Eugene Curtis
William E. Quist
Michael V. Hyatt
Sven E. Axter
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Boeing Co
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Boeing Co
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Publication date
Application filed by Boeing Co filed Critical Boeing Co
Publication of EP0214381A1 publication Critical patent/EP0214381A1/fr
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Publication of EP0214381B1 publication Critical patent/EP0214381B1/fr
Expired legal-status Critical Current

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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
    • C22C21/12—Alloys based on aluminium with copper as the next major constituent

Definitions

  • the present invention relates to aluminum-lithium alloys and more particularly to an aluminum-lithium alloy composition with good fracture toughness and high strength.
  • the alloy NOR 81 comprises a too high zirconium concentration (0.19% by wt) and further such a magnesium concentration (0.56% by wt), that this NOR 81 chemical composition falls outside the single phase region of Al-Li-Mg-Cu-alloys. Accordingly, the NOR 81 alloy would contain an appreciable volume percentage of solid intermetallic particles deteriorating the fracture toughness. Furthermore, the reported strong presence of the ⁇ Al3Zr phase in the as-extruded and all aged conditions indicates that the zirconium content of the NOR 81 alloy is too rich in zirconium. These ⁇ -phase particles are detrimental to the fracture toughness.
  • EP-A-157,600 (date of publication October 9, 1985) relates to an aluminum-lithium base alloy wrought product comprising 0.5 to 4.0 weight percent Li, 0 to 5.0 weight percent Mg, up to 5.0 weight percent Cu, 0 to 1.0 weight percent Zr, 0 to 2.0 weight percent Mn, 0 to 7.0 weight percent Zn, 0.5 weight percent max. Fe, 0.5 weight percent max. Si, the balance aluminum and incidental impurities.
  • the product has imparted thereto prior to an aging step, a working effect equivalent to stretching in an amount greater than 3% in order to improve strength and fracture toughness combinations.
  • Example II discloses an aluminum alloy consisting of by weight 2.0% Li, 2.7% Cu, 0.65% Mg and 0.12% Zr, the balance essentially aluminum and impurities. Inventive specimens stretched for 6% were compared with a single comparative example stretched for 2% and aged for 72 hours at 162°C (325°F).
  • the present invention provides processes for manufacturing an article from a novel aluminum alloy composition that can be worked and heat treated so as to provide an aluminum-lithium alloy artical with high strength, good fracture toughness, and relatively low density compared to conventional aluminum alloys such as 7XXX and 2XXX series alloys that it is intended to replace.
  • a first process according to the invention comprises the steps of: a) preparing an alloy of the following composition: element amount (% by wt) Li 2.0 to 2.4 Mg 0.3 to 0.9 Cu 2.1 to 2.9 Zr 0.08 to 0.15 Fe 0.15 max Si 0.12 max Zn 0.25 max Ti 0.15 max Cr 0.1 max other trace elements, each 0.05 max total of other trace elements 0.15 max Al Balance b) forming an article from said alloy; c) subjecting the article to a solution heat treatment; d) quenching the article in a quenching medium; and e) subjecting the quenched article to an aging treatment, and is chacacterized in that the aging treatment comprising aging to near peak strength at an aging temperature being in the range of 162°C (325°F) to 176°C (350°F), disclaiming an aluminum-lithium alloy consisting of, by weight, 2.0% Li, 2.7% Cu, 0.65% Mg and 0.12% Zr, the balance essentially aluminum and impurities, being 2% stretched and
  • a second process according to the invention comprises the steps of: a) preparing an alloy of the following composition: element amount (% by wt) Li 2.0 to 2.4 Mg 0.3 to 0.9 Cu 2.1 to 2.9 Zr 0.08 to 0.15 Fe 0.15 max Si 0.12 max Zn 0.25 max Ti 0.15 max Cr 0.1 max other trace elements, each 0.05 max total of other trace elements 0.15 max Al Balance b) forming an article from said alloy; c) subjecting the article to a solution heat treatment; d) quenching the article in a quenching medium; and e) subjecting the quenched article to an aging treatment, and is characterized in that the aging treatment comprises naturally aging.
  • An alloy prepared in accordance with the present invention has a nominal composition on the order of 2.2 weight percent lithium, 0.6 percent magnesium, 2, 5 percent copper and 0.12 percent zirconium.
  • Artificial aging of the alloy at a temperature in the range of 162 to 176°C (325 to 350°F) to a near-peak age condition results in high strengths comparable to those of current 7XXX-T6 alloys in combination with good toughness and resistance to stress corrosion cracking.
  • strength and fracture toughness levels equivalent to or better than those of existing 2XXX-T3 type alloys are obtained.
  • An aluminum-lithium alloy formulated in accordance with the present invention can contain from about 2.0 to about 2.4 percent lithium, 0.3 to 0.9 percent magnesium, 2.1 to 2,9 percent copper, and from about 0.08 to a maximum of 0.15 percent zirconium as a grain refiner. Preferably from about 0.09 to 0.14 percent zirconium is incorporated. All percentages herein are by weight percent based on the total weight of the alloy unless otherwise indicated.
  • the magnesium is included to increase strength without increasing density. Preferred amounts of magnesium range from about 0.4 to 0.8 percent, with 0.6 percent being most preferred.
  • the copper adds strength to the alloy.
  • Iron and silicon can each be present in maximums up to a total of 0.3 percent. It is preferred that these impurities be present only in trace amounts, limiting the iron to a maximum of 0.15 percent and the silicon to a maximum of 0.12 percent, and preferably to maximums of 0.10 and 0.10 percent, respectively.
  • the element zinc may be present in amounts up to but not exceeding 0.25 percent of the total. Titanium and chromium should not exceed 0.15 percent and 0.10 percent, respectively. Other elements such as manganese must each be held to levels of 0.05 percent or below, and the total amount of such other trace elements must be held to a maximum 0.15 percentage. If the foregoing maximums are exceeded the desired properties of the aluminum-lithium alloy will tend to deteriorate.
  • the trace elements sodium and hydrogen are also thought to be harmful to the properties (fracture toughness in particular) of aluminum-lithium alloys and should be held to the lowest levels practically attainable, for example on the order of 15 to 30 ppm (0.0015-0.0030 wt.%) or less for the sodium and less than 15 ppm (0.0015 wt.%) and preferably less than 1.0 ppm (0.0001 wt. %) for the hydrogen.
  • the balance of the alloy comprises aluminum.
  • An aluminum-lithium alloy formulated in the proportions set forth in the foregoing two paragraphs is processed into an article utilizing known techniques.
  • the alloy is formulated in molten form and cast into an ingot.
  • the ingot is then homogenized at temperatures ranging from 496 to 543°C (925 to 1010°F) or higher.
  • the alloy is converted into a usable article by conventional mechanical formation techniques such as rolling, extrusion, or the like.
  • the alloy is normally subjected to a solution treatment at temperatures ranging from 510 to 543°C (950 to 1010°F), followed by quenching in a quenching medium such as water that is maintained at a temperature on the order of 21 to 65°C (70 to 150°F). If the alloy has been rolled or extruded, it is generally stretched on the order of 1 to 3 percent of its original length to relieve internal stresses, and to provide improved age-hardening response.
  • the alumium alloy can then be further worked and formed by secondary operations into the various shapes for its final application. Additional heat treatments such as solution heat treatment and/or aging can be employed if desired after such forming operations. For example, sheet products after stretch forming to the desired shapes may be re-solution heat treated at a temperature on the order of 535°C (995°F) for 10 minutes to one hour. The article is normally then quenched in a quenching medium held at temperatures ranging from about 21 to 65°C (70 to 150°F).
  • the alloy is subjected to an aging treatment at moderately low temperatures on the order of from 162 to 176°C (325 to 350°F).
  • the alloy can be aged for a period of time that will allow it to achieve near peak strength, preferably about 95 percent, and most preferably about 95 to 97 percent, of its peak strength. This level of strength can be achieved by aging for about 4 to 120 hours, and preferably for about 24 to 96 hours.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Extrusion Of Metal (AREA)
  • Forging (AREA)

Claims (14)

  1. Un procédé de fabrication d'un produit en un alliage d'aluminium et de lithium comprenant les étapes suivantes :
    a) préparation d'un alliage ayant la composition suivante : élément quantité (% en poids) Li 2,0 à 2,4 Mg 0,3 à 0,9 Cu 2,1 à 2,9 Zr 0,08 à 0,15 Fe 0,15 max Si 0,12 max Zn 0,25 max Ti 0,15 max Cr 0,1 max autres éléments à l'état de trace, chacun 0,05 max total des autres éléments à l'état de trace 0,15 max Al le restant
    b) formation d'un article à partir dudit alliage ;
    c) traitement de l'article par un traitement thermique en solution ;
    d) trempe de l'article dans un milieu de trempe ; et
    e) traitement de l'article trempé par un traitement de vieillissement, caractérisé en ce que le traitement de vieillissement comprend le vieillissement au voisinage du pic de résistance à une température de vieillissement dans l'intervalle de 162°C (325°F) à 176°C (350°F),
       renonçant à un alliage d'aluminium et de lithium constitué en poids de 2,0% de Li, 2,7% de Cu, 0,65% de Mg et 0,12% de Zr, le restant étant essentiellement de l'aluminium et des impuretés, étant étiré à 2% et vieilli pendant 72 h à 162°C (325°F).
  2. Un procédé de fabrication d'un produit d'un alliage d'aluminium et de lithium comprenant les étapes suivantes :
    a) préparation d'un alliage ayant la composition suivante : élément quantité (% en poids) Li 2,0 à 2,4 Mg 0,3 à 0,9 Cu 2,1 à 2,9 Zr 0,08 à 0,15 Fe 0,15 max Si 0,12 max Zn 0,25 max Ti 0,15 max Cr 0,1 max autres éléments à l'état de trace, chacun 0,05 max total des autres éléments à l'état de trace 0,15 max Al le restant
    b) formation d'un article à partir dudit alliage ;
    c) traitement de l'article par un traitement thermique en solution ;
    d) trempe de l'article dans un milieu de trempe ; et
    e) traitement de l'article trempé par un traitement de vieillissement,
    caractérisé en ce que le traitement de vieillissement comprend le vieillissement naturel.
  3. Procédé selon la revendication 1, selon lequel le traitement de vieillissement comprend le vieillissement à environ 95% du pic de résistance.
  4. Procédé selon la revendication 1 ou 3, selon lequel le traitement du vieillissement comprend le vieillissement à environ 95 à 97% du pic de résistance.
  5. Procédé selon la revendication 1, 3 ou 4, selon lequel le traitement de vieillissement comprend le vieillissement pendant environ 4 à 120 h.
  6. Procédé selon la revendication 1 ou 3-5, selon lequel le traitement de vieillissement comprend le vieillissement pendant environ 24 à 96 h.
  7. Procédé selon la revendication 2, selon lequel le traitement de vieillissement comprend le vieillissement naturel pendant une période de temps de 4 à 7 jours.
  8. Procédé selon la revendication 1-7, selon lequel l'article trempé est soumis à un étirage avant le traitement de vieillissement.
  9. Procédé selon la revendication 8, selon lequel l'article est étiré de l'ordre de 1 à 3%.
  10. Procédé selon la revendication 1-9, selon lequel le lithium est présent en quantité dans l'intervalle d'environ 2,0 à 2,2% en poids.
  11. Procédé selon la revendication 1-10, selon lequel le magnésium est présent en quantité dans l'intervalle d'environ 0,4 à 0,8% en poids.
  12. Procédé selon la revendication 1-11, selon lequel le magnésium est présent en quantité de 0,6% en poids.
  13. Procédé selon la revendication 1-12, selon lequel le zirconium est présent en quantité de 0,09 à 0,14% en poids.
  14. Procédé selon la revendication 1-13, selon lequel un alliage est préparé ayant une composition nominale de 2,2% en poids de lithium, 0,6% en poids de magnésium, 2,5% en poids de cuivre et 0,12% en poids de zirconium.
EP19860108331 1985-08-20 1986-06-19 Alliage aluminium-lithium Expired EP0214381B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US78854185A 1985-08-20 1985-08-20
US788541 1985-08-20

Publications (2)

Publication Number Publication Date
EP0214381A1 EP0214381A1 (fr) 1987-03-18
EP0214381B1 true EP0214381B1 (fr) 1991-12-18

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EP19860108331 Expired EP0214381B1 (fr) 1985-08-20 1986-06-19 Alliage aluminium-lithium

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EP (1) EP0214381B1 (fr)
DE (2) DE3613224A1 (fr)

Families Citing this family (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5137686A (en) * 1988-01-28 1992-08-11 Aluminum Company Of America Aluminum-lithium alloys
US4961792A (en) * 1984-12-24 1990-10-09 Aluminum Company Of America Aluminum-lithium alloys having improved corrosion resistance containing Mg and Zn
DE3670510D1 (de) * 1985-11-28 1990-05-23 Pechiney Rhenalu Verfahren zur desensibilisierung gegen abschieferungskorrosion bei lithium enthaltenden aluminiumlegierungen, wobei gleichzeitig hohe mechanische festigkeitswerte erhalten werden und der schaden begrenzt bleibt.
US5108519A (en) * 1988-01-28 1992-04-28 Aluminum Company Of America Aluminum-lithium alloys suitable for forgings
US5066342A (en) * 1988-01-28 1991-11-19 Aluminum Company Of America Aluminum-lithium alloys and method of making the same
DE68913561T2 (de) * 1988-01-28 1994-10-20 Aluminum Co Of America Aluminium-Lithium-Legierungen.
US4869870A (en) * 1988-03-24 1989-09-26 Aluminum Company Of America Aluminum-lithium alloys with hafnium
CN113981341B (zh) * 2021-11-05 2022-04-26 西南铝业（集团）有限责任公司 一种高强高韧耐腐蚀2196-t8511铝锂合金挤压型材及其生产工艺

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS59118848A (ja) * 1982-12-27 1984-07-09 Sumitomo Light Metal Ind Ltd 電気抵抗を高めた構造用アルミニウム合金
EP0156995B1 (fr) * 1983-12-30 1994-09-28 Aluminum Company Of America Alliage aluminium-lithium
EP0151301B1 (fr) * 1983-12-30 1989-06-07 The Boeing Company Alliage aluminium-lithium
FR2561260B1 (fr) * 1984-03-15 1992-07-17 Cegedur Alliages al-cu-li-mg a tres haute resistance mecanique specifique

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Publication number Publication date
DE3682983D1 (de) 1992-01-30
DE3613224A1 (de) 1987-02-26
EP0214381A1 (fr) 1987-03-18

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