RU2815234C2 - Alloys based on aluminium and lithium of 2xxx series - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: invention relates namely to the alloys based on aluminium and lithium of the 2xxx series and to products made from them. A product made of an aluminium-based alloy of the 2xxx series, obtained by pressure treatment, contains, wt.%: 3.1-3.8 Cu, 0.82-1.20 Li, 0.85-2.0 Zn, 0.10-0.60 Mn, 0.05-0.35 Mg, from 0.05 to 0.50 of at least one grain structure control element selected from the group consisting of Zr, Sc, Cr, V, Hf, other rare earth elements and combinations thereof, not more than 0.22 Ag, not more than 0.15 Fe, not more than 0.12 Si and not more than 0.15 Ti, the rest being aluminium, optional minor elements and impurities. Minor elements, when present, are included at a total content of not more than 1.0 wt.%. The 2xxx series aluminium alloy forming product is one of a plate product, an extruded product, or a forged product.

EFFECT: product is characterized by an improved combination of strength, fracture toughness, elongation and corrosion resistance.

25 cl, 3 dwg, 8 tbl, 2 ex

Description

FIELD OF TECHNOLOGY TO WHICH THE INVENTION RELATES

[001] The present invention relates to 2xxx series aluminum and lithium alloys and products made therefrom.

BACKGROUND OF THE ART

[002] Aluminum-based alloys are useful in a variety of applications. However, improving one property of an aluminum-based alloy without compromising another property often proves difficult. For example, it is difficult to increase the strength of an alloy without reducing the toughness of the alloy. Other properties of aluminum-based alloys of interest include corrosion resistance and fatigue crack growth resistance, as two examples.

BRIEF DESCRIPTION OF THE INVENTION

[003] In general, this patent application relates to the new 2xxx series aluminum and lithium based alloys. Typically, the new 2xxx series aluminum and lithium based alloys contain (and in some cases consist essentially or consist of) 2.5 to 3.9 wt. % Cu, 0.82 to 1.20 wt. % Li, from 0.5 to 2.0 wt. % Zn, from 0.10 to 0.60 wt. % Mn, from 0.05 to 0.35 wt. % Mg; from 0.05 to 0.50 wt. % of at least one grain structure control element, wherein the at least one grain structure control element is selected from the group consisting of Zr, Sc, Cr, V, Hf, other rare earth elements and combinations thereof, not more than 0.22 wt . % Ag, no more than 0.15 wt. % Fe, no more than 0.12 wt. % Si and not more than 0.15 wt. % Ti, with the remainder being aluminum, minor elements and impurities. Products incorporating compositions based on such an alloy may have an improved combination of, for example, two or more of strength, elongation, fracture toughness, and stress corrosion cracking resistance.

i. Compound

[004] As stated above, copper (Cu) is included in the alloy and is typically present in the range of 2.5 wt. % up to 3.9 wt. % Cu. More specific embodiments that relate to copper are presented towards the end of this section.

[005] As stated above, lithium (Li) is included in the new alloy and is typically present in the range of 0.82 wt. % up to 1.20 wt. %. In one embodiment, the new alloy includes at least 0.85 wt. % Li. In another embodiment, the new alloy includes at least 0.875 wt. % Li. In yet another embodiment, the new alloy includes at least 0.90 wt. % Li. In another embodiment, the new alloy includes at least 0.925 wt. % Li. In another embodiment, the new alloy includes at least 0.95 wt. % Li. In one embodiment, the new alloy includes no more than 1.15 wt. % Li. In another embodiment, the new alloy includes no more than 1.10 wt. % Li. In yet another embodiment, the new alloy includes no more than 1.075 wt. % Li. In another embodiment, the new alloy includes no more than 1.050 wt. % Li. In yet another embodiment, the new alloy includes no more than 1.025 wt. % Li. In another embodiment, the new alloy includes no more than 1,000 wt. % Li. In yet another embodiment, the new alloy includes no more than 0.980 wt. % Li.

[006] Zinc (Zn) is typically included in the new alloy and is typically present in the range of 0.50 wt. % Zn up to 2.0 wt. %Zn. More specific embodiments that relate to zinc are presented towards the end of this section.

[007] The weight ratio of copper to zinc in an alloy may be related to its improved properties (eg, quench sensitivity). In one embodiment, the new 2xxx series aluminum-based alloy exhibits a copper to zinc weight ratio of no more than 4.25:1 (Cu:Zn).

[008] Manganese (Mn) is typically included in the new alloy and is typically present in the range of 0.10 wt. % up to 0.60 wt. % Mn. In one embodiment, the new alloy includes at least 0.125 wt. % Mn. In another embodiment, the new alloy includes at least 0.15 wt. % Mn. In yet another embodiment, the new alloy includes at least 0.175 wt. % Mn. In another embodiment, the new alloy includes at least 0.20 wt. % Mn. In another embodiment, the new alloy includes at least 0.225 wt. % Mn. In yet another embodiment, the new alloy includes at least 0.25 wt. % Mn. In another embodiment, the new alloy includes at least 0.27 wt. % Mn. In one embodiment, the new alloy includes no more than 0.55 wt. % Mn. In another embodiment, the new alloy includes no more than 0.50 wt. % Mn. In yet another embodiment, the new alloy includes no more than 0.45 wt. % Mn. In another embodiment, the new alloy includes no more than 0.425 wt. % Mn. In yet another embodiment, the new alloy includes no more than 0.40 wt. % Mn. In another embodiment, the new alloy includes no more than 0.375 wt. % Mn. In yet another embodiment, the new alloy includes no more than 0.35 wt. % Mn. In another embodiment, the new alloy includes no more than 0.325 wt. % Mn. In another embodiment, the new alloy includes no more than 0.30 wt. % Mn. In the field of alloying, manganese can be considered both an alloying ingredient and a grain structure control element—manganese held in solid solution can improve the alloy's mechanical properties (e.g., strength and/or toughness), while manganese in particulate form (e.g. in the form of Al ₆ Mn, Al ₁₂ Mn ₃ Si ₂ , Al ₂₀ Cu ₂ Mn ₃ - sometimes called dispersed particles) can help control grain structure and also improve damage tolerance properties such as fracture toughness. However, since Mn is specifically defined with its composition limits in this patent application, it is not included in the definition of “grain structure control element” (described below) for purposes of this patent application.

[009] Magnesium (Mg) is included in the new alloy and is typically present in the range of 0.05 wt. % up to 0.35 wt. % Mg. More specific embodiments that relate to magnesium are presented towards the end of this section.

[0010] The alloy may include from 0.05 to 0.50 wt. % of at least one grain structure control element selected from the group consisting of zirconium (Zr), scandium (Sc), chromium (Cr), vanadium (V), and/or hafnium (Hf), and/or other rare earths elements, and wherein the grain structure control element(s) are present in amounts below maximum solubility. As used herein, "grain structure control element" means elements or compounds specifically added during alloying to form secondary phase particles, typically in the solid state, to provide control of changes in grain structure in the solid state during thermal processes such as reduction and recrystallization. For purposes of this patent application, grain structure control elements include Zr, Sc, Cr, V, Hf and other rare earth elements, as a few examples, but do not include Mn.

[0011] The amount of grain structure control material used in the alloy generally depends on the type of grain structure control material used and/or the method for producing the alloy. In one approach, the grain structure control element is Zr, and the alloy includes from 0.05 wt. % up to 0.20 wt. % Zr. In one embodiment, the aluminum-based alloy includes at least 0.06 wt. % Zr. In another embodiment, the aluminum-based alloy includes at least 0.07 wt. % Zr. In yet another embodiment, the aluminum-based alloy includes at least 0.08 wt. % Zr. In one embodiment, the aluminum-based alloy includes no more than 0.18 wt. % Zr. In another embodiment, the aluminum-based alloy includes no more than 0.16 wt. % Zr. In another embodiment, the aluminum-based alloy includes no more than 0.15 wt. % Zr. In yet another embodiment, the aluminum-based alloy includes no more than 0.14 wt. % Zr. In another embodiment, the aluminum-based alloy includes no more than 0.13 wt. % Zr. In one embodiment, the alloy includes from 0.05 wt. % up to 0.15 wt. % Zr. In another embodiment, the alloy includes from 0.07 wt. % up to 0.14 wt. % Zr. In another embodiment, the alloy includes from 0.08 wt. % up to 0.13 wt. % Zr.

[0012] The alloy may include no more than 0.15 wt. % Ti total for grain size reduction and/or other purposes. Grain size reduction additives are modifiers or nucleators for the formation of new grains during solidification of the alloy. An example of a grain size reduction additive is a 9.525 mm diameter rod containing 96% aluminum, 3% titanium (Ti) and 1% boron (B) (all percent by weight), where virtually all of the boron is in the form of fine TiB ₂ particles. During casting, a rod of grain size reduction additive can be fed in a stream into the molten alloy entering the casting pit at a controlled rate. The amount of grain size reduction additive included in the alloy generally depends on the type of material used to provide grain size reduction and the method of producing the alloy. Examples of grain size reduction additives include Ti in combination with B (eg TiB ₂ ) or with carbon (TiC), but other grain size reduction additives such as Al-Ti master alloys can also be used. Typically, grain size reduction additives are added to the alloy in amounts ranging from 0.0003 wt. % up to 0.005 wt. %, depending on the required grain size in the cast state. In addition, Ti can be added to the alloy separately in an amount of no more than 0.15 wt. %, depending on the product shape, to increase the effectiveness of the grain size reduction additive, and typically in the range of 0.005 to 0.15 wt. % Ti. When Ti is included in an alloy, it is typically present in an amount of 0.01 to 0.10 wt. %. In one embodiment, the new alloy includes at least 0.005 wt. % Ti. In another embodiment, the new alloy includes at least 0.01 wt. % Ti. In yet another embodiment, the new alloy includes at least 0.015 wt. % Ti. In another embodiment, the new alloy includes at least 0.020 wt. % Ti. In one embodiment, the new alloy includes no more than 0.10 wt. % Ti. In another embodiment, the new alloy includes no more than 0.08 wt. % Ti. In yet another embodiment, the new alloy includes no more than 0.07 wt. % Ti. In another embodiment, the new alloy includes no more than 0.06 wt. % Ti. In yet another embodiment, the new alloy includes no more than 0.05 wt. % Ti. In one embodiment, the aluminum-based alloy includes a grain size reduction additive, and the grain size reduction additive is at least one of TiB ₂ and TiC, wherein wt. % Ti in the alloy ranges from 0.01 to 0.06 wt. %, or from 0.01 to 0.03 wt. %.

[0013] The new aluminum-based alloy may include iron (Fe). The iron content in a new alloy usually does not exceed 0.15 wt. %. In one embodiment, the new alloy may include at least 0.01 wt. % Fe. In one embodiment, the new alloy includes no more than 0.12 wt. % Fe. In another embodiment, the new alloy includes no more than 0.10 wt. % Fe. In yet another embodiment, the new alloy includes no more than 0.08 wt. % Fe. In another embodiment, the new alloy includes no more than 0.06 wt. % Fe. In yet another embodiment, the new alloy includes no more than 0.04 wt. % Fe.

[0014] The new aluminum-based alloy may include silicon (Si). The silicon content in a new alloy should usually not exceed 0.12 wt. %. In one embodiment, the new alloy may include at least 0.01 wt. %Si. In one embodiment, the new alloy includes no more than 0.10 wt. %Si. In another embodiment, the new alloy includes no more than 0.08 wt. %Si. In yet another embodiment, the new alloy includes no more than 0.06 wt. %Si. In another embodiment, the new alloy includes no more than 0.04 wt. %Si.

[0015] As stated above, the new aluminum-based alloy may optionally include silver in an amount of no more than 0.22 wt. %. In one embodiment, the new alloy includes no more than 0.20 wt. % Ag. In another embodiment, the new alloy includes no more than 0.15 wt. % Ag. In yet another embodiment, the new alloy includes no more than 0.10 wt. % Ag. In another embodiment, the new alloy includes no more than 0.05 wt. % Ag. In yet another embodiment, the new alloy includes no more than 0.01 wt. % Ag. In another embodiment, the new alloy includes no more than 0.005 wt. % Ag and/or, or it is not detectable in the new alloy.

[0016] As stated above, new alloys typically include the alloying ingredients set forth, with the balance being aluminum, optional minor elements and impurities. As used herein, "minor elements" means elements or materials other than the above elements that may optionally be added to the alloy to facilitate the production of the alloy. Examples of minor elements include casting aids such as grain size reducers and deoxidizing agents. Optional minor elements can be included in the alloy in a total amount of not more than 1.0 weight. %. As one non-limiting example, one or more minor elements may be added to the alloy during casting to reduce or limit (and in some cases eliminate) cracking of the ingot caused by, for example, oxide folding, pitting, and oxide staining. These types of minor elements are generally referred to herein as deoxidizers. Examples of some deoxidizing agents include Ca, Sr and Be. When calcium (Ca) is included in the alloy, it is typically present in an amount of no more than about 0.05 weight. %, or not more than about 0.03 wt. %. In some embodiments, Ca is included in the alloy in an amount of approximately 0.001 to 0.03 wt. % or approximately 0.05 wt. %, for example 0.001-0.008 wt. % (or from 10 to 80 ppm). Strontium (Sr) may be included in the alloy as a substitute for Ca (in whole or in part) and thus may be included in the alloy in an amount similar to or similar to that of Ca. Traditionally, the addition of beryllium (Be) has helped reduce the cracking tendency of the ingot, but for environmental, health and safety reasons, some embodiments of the alloy are essentially Be-free. If Be is included in the alloy, it is typically present in an amount of no more than about 20 ppm. Minor elements may be present in minor quantities or may be present in significant quantities and may themselves provide the required or other characteristics without departing from the essence of the alloy described herein, provided that the alloy retains the necessary characteristics described herein. However, it should be understood that the scope of the present invention should not be circumvented by simply adding an element or elements in amounts that do not have any effect on the desired and obtained property combinations herein.

[0017] The new 2xxx series aluminum-based alloys typically contain small amounts of impurities. In one embodiment, the new 2xxx series aluminum-based alloy includes a total of no more than 0.15 wt. % of impurities, and at the same time the aluminum-based alloy of the 2xxx series includes no more than 0.05 wt. % of each impurity. In another embodiment, the new 2xxx series aluminum-based alloy includes a total of no more than 0.10 wt. % of impurities, and the alloy based on aluminum of the 2xxx series includes no more than 0.03 wt. % of each impurity.

a. Illustrative first version of the new 2xxx series aluminum alloy

[0018] In one embodiment, the first version of the new 2xxx series aluminum-based alloy includes a first set of tailored amounts of copper, magnesium and zinc. In one approach, the first version includes 3.1 to 3.8 wt. % copper, from 0.5 to 2.0 wt. % Zn and from 0.05 to 0.35 wt. % Mg.

[0019] In one embodiment, the first version includes at least 3.2 wt. % Cu. In another embodiment, the first version includes at least 3.3 wt. % Cu. In one embodiment, the first version includes no more than 3.75 wt. % Cu. In another embodiment, the first version includes no more than 3.7 wt. % Cu. In one embodiment, the first version includes no more than 3.65 wt. % Cu. In another embodiment, the first version includes no more than 3.6 wt. % Cu.

[0020] In one embodiment, the first version includes at least 0.6 wt. %Zn. In another embodiment, the first version includes at least 0.7 wt. %Zn. In yet another embodiment, the first version includes at least 0.75 wt. %Zn. In another embodiment, the first version includes at least 0.8 wt. %Zn. In yet another embodiment, the first version includes at least 0.85 wt. %Zn. In another embodiment, the first version includes at least 0.9 wt. %Zn. In yet another embodiment, the first version includes at least 0.95 wt. %Zn. In one embodiment, the first version includes no more than 1.8 wt. %Zn. In another embodiment, the first version includes no more than 1.6 wt. %Zn. In yet another embodiment, the first version includes no more than 1.4 wt. %Zn. In another embodiment, the first version includes no more than 1.3 wt. %Zn. In yet another embodiment, the first version includes no more than 1.2 wt. %Zn. In another embodiment, the first version includes no more than 1.1 wt. %Zn. In yet another embodiment, the first version includes no more than 1.05 wt. %Zn.

[0021] As stated above, the weight ratio of copper to zinc in an alloy may be related to its improved properties (eg, quench sensitivity). In one embodiment, the first version exhibits a copper to zinc ratio (by weight) of no more than 4.25:1 (Cu:Zn), i.e. (wt% Cu) / (wt% Zn) in the alloy is no more than 4.25. In another embodiment, the first version exhibits a copper to zinc ratio (by weight) of no more than 4.10:1. In yet another embodiment, the first version exhibits a copper to zinc ratio (by weight) of no more than 4.00:1. In another embodiment, the first version exhibits a copper to zinc ratio (by weight) of no more than 3.90:1. In yet another embodiment, the first version exhibits a copper to zinc ratio (by weight) of no more than 3.80:1. In another embodiment, the first version exhibits a copper to zinc ratio (by weight) of no more than 3.78:1.

[0022] In one embodiment, the first version includes at least 0.10 wt. % Mg. In another embodiment, the first version includes at least 0.125 wt. % Mg. In yet another embodiment, the first version includes at least 0.15 wt. % Mg. In another embodiment, the first version includes at least 0.175 wt. % Mg. In yet another embodiment, the first version includes at least 0.20 wt. % Mg. In another embodiment, the first version includes at least 0.21 wt. % Mg. In yet another embodiment, the first version includes at least 0.22 wt. % Mg. In one embodiment, the first version includes no more than 0.325 wt. % Mg. In another embodiment, the first version includes no more than 0.30 wt. % Mg. In yet another embodiment, the first version includes no more than 0.29 wt. % Mg. In another embodiment, the first version includes no more than 0.28 wt. % Mg.

[0023] Various embodiments of the first version of the 2xxx series alloy are presented below.

TABLE 1a. Illustrative alloys according to version 1 (percentage by weight)

Alloy Cu Li Zn Mn Mg Ag 1V-1 3.1-3.8 0.82-1.20 0.5-2.0 0.10-0.60 0.05-0.35 ≤ 0.22 1V-2 3.2-3.75 0.85-1.15 0.6-1.8 0.15-0.55 0.10-0.325 ≤ 0.005 1V-3 3.2-3.7 0.875-1.10 0.7-1.6 0.20-0.45 0.125-0.30 ≤ 0.005 1V-4 3.3-3.7 0.90-1.075 0.75-1.4 0.20-0.425 0.15-0.29 ≤ 0.005 1V-5 3.3-3.65 0.90-1.050 0.8-1.3 0.225-0.40 0.175-0.29 ≤ 0.005 1V-6 3.3-3.6 0.90-1.025 0.85-1.2 0.225-0.375 0.20-0.29 ≤ 0.005 1V-7 3.3-3.6 0.90-1.000 0.9-1.1 0.25-0.35 0.21-0.28 ≤ 0.005 1V-8 3.3-3.6 0.90-1.000 0.95-1.05 0.27-0.325 0.22-0.28 ≤ 0.005

TABLE 1b. Illustrative alloys according to version one (percentage by weight) (cont.)

Alloy Cu:Zn G.S.C. ^* Fe Si Ti Impurities (each/
Total) The rest ^** 1V-1 ≤ 4.25:1 0.05-0.20 Zr ≤ 0.15 ≤ 0.12 ≤ 0.15 ≤ 0.05 /
≤ 0.15 Al and optional second growth elem. 1V-2 ≤ 4.25:1 0.05-0.18 Zr ≤ 0.12 ≤ 0.10 0.01-0.10 ≤ 0.05 /
≤ 0.15 Al and optional second growth elem. 1V-3 ≤ 4.25:1 0.05-0.16 Zr ≤ 0.10 ≤ 0.08 0.01-0.10 ≤ 0.05 /
≤ 0.15 Al and optional second growth elem. 1V-4 ≤ 4.25:1 0.05-0.15 Zr ≤ 0.08 ≤ 0.06 0.01-0.10 ≤ 0.05 /
≤ 0.15 Al and optional second growth elem. 1V-5 ≤ 4.25:1 0.05-0.15 Zr ≤ 0.08 ≤ 0.06 0.01-0.10 ≤ 0.05 /
≤ 0.15 Al and optional second growth elem. 1V-6 ≤ 4.10:1 0.05-0.15 Zr ≤ 0.08 ≤ 0.06 0.01-0.10 ≤ 0.03 /
≤ 0.10 Al and optional second growth elem. 1V-7 ≤ 4.00:1 0.05-0.15 Zr ≤ 0.08 ≤ 0.06 0.01-0.10 ≤ 0.03 /
≤ 0.10 Al and optional second growth elem. 1V-8 ≤ 3.78:1 0.05-0.15 Zr ≤ 0.06 ≤ 0.04 0.01-0.10 ≤ 0.03 /
≤ 0.10 Al and optional second growth elem.

*GSC=Grain Structure Control.

**Optional second growth elem. = optional minor elements.

[0024] In one embodiment, the first version includes 3.2-3.7 wt. % Cu, 0.85-1.15 wt. % Li, 0.75-1.25 wt. % Zn, where Cu:Zn (weight ratio) is ≤ 4.25:1, 0.15-0.29 wt. % Mg, (X1, X2, X3, X4 or X5) wt. % Mn, ≤ 0.005 wt. % Ag, 0.05-0.15 wt. % Zr, ≤ 0.10 wt. % Fe, ≤ 0.08 wt. % Si, 0.01-0.10 wt. % Ti, with the remainder being aluminum, optional minor elements and impurities, where X1 means 0.15-0.40 (i.e. X1 wt % Mn means 0.15-0.40 wt % Mn) where X2 means 0.15-0.30, where X3 means 0.15-0.25, where X4 means 0.20-0.40, and where X5 means 0.25-0.35.

b. Illustrative second version of the new 2xxx series aluminum alloy

[0025] In one embodiment, a second version of the new 2xxx series aluminum-based alloy includes a second set of tailored amounts of copper, magnesium and zinc. In one approach, the second version includes 2.5 to 3.4 weight. % copper, from 0.5 to 2.0 wt. % Zn and from 0.05 to 0.35 wt. % Mg.

[0026] In one embodiment, the second version includes at least 2.6 wt. % Cu. In another embodiment, the second version includes at least 2.7 wt. % Cu. In yet another embodiment, the second version includes at least 2.8 wt. % Cu. In another embodiment, the second version includes at least 2.85 wt. % Cu. In one embodiment, the second version includes no more than 3.35 wt. % Cu. In another embodiment, the second version includes no more than 3.3 wt. % Cu. In one embodiment, the second version includes no more than 3.25 wt. % Cu. In another embodiment, the second version includes no more than 3.2 wt. % Cu. In another embodiment, the second version includes no more than 3.15 wt. % Cu.

[0027] In one embodiment, the second version includes at least 0.6 wt. %Zn. In another embodiment, the second version includes at least 0.8 wt. %Zn. In yet another embodiment, the second version includes at least 1.0 wt. %Zn. In another embodiment, the second version includes at least 1.1 wt. %Zn. In yet another embodiment, the second version includes at least 1.2 wt. %Zn. In another embodiment, the second version includes at least 1.3 wt. %Zn. In one embodiment, the second version includes no more than 1.9 wt. %Zn. In another embodiment, the second version includes no more than 1.8 wt. %Zn. In yet another embodiment, the second version includes no more than 1.7 wt. %Zn. In another embodiment, the second version includes no more than 1.6 wt. %Zn. In yet another embodiment, the second version includes no more than 1.5 wt. %Zn.

[0028] As stated above, the weight ratio of copper to zinc in an alloy may be related to its improved properties (eg, quench sensitivity). In one embodiment, the second version exhibits a copper to zinc ratio (by weight) of no more than 4.25:1 (Cu:Zn), i.e. (wt% Cu) / (wt% Zn) in the alloy is no more than 4.00:1. In another embodiment, the second version exhibits a copper to zinc ratio (by weight) of no more than 3.75:1. In yet another embodiment, the second version exhibits a copper to zinc ratio (by weight) of no more than 3.50:1. In another embodiment, the second version exhibits a copper to zinc ratio (by weight) of no more than 3.30:1. In yet another embodiment, the second version exhibits a copper to zinc ratio (by weight) of no more than 3.10:1. In another embodiment, the second version exhibits a copper to zinc ratio (by weight) of no more than 2.95:1. In yet another embodiment, the second version exhibits a copper to zinc ratio (by weight) of no more than 2.90:1. In another embodiment, the second version exhibits a copper to zinc ratio (by weight) of no more than 2.75:1. In another embodiment, the second version exhibits a copper to zinc ratio (by weight) of no more than 2.67:1. In another embodiment, the second version exhibits a copper to zinc ratio (by weight) of no more than 2.50:1. In another embodiment, the second version exhibits a copper to zinc ratio (by weight) of no more than 2.42:1.

[0029] In one embodiment, the second version includes at least 0.10 wt. % Mg. In another embodiment, the second version includes at least 0.12 wt. % Mg. In yet another embodiment, the second version includes at least 0.13 wt. % Mg. In another embodiment, the second version includes at least 0.14 wt. % Mg. In yet another embodiment, the second version includes at least 0.15 wt. % Mg. In another embodiment, the second version includes at least 0.16 wt. % Mg. In yet another embodiment, the second version includes at least 0.17 wt. % Mg. In one embodiment, the second version includes no more than 0.30 wt. % Mg. In another embodiment, the second version includes no more than 0.275 wt. % Mg. In yet another embodiment, the second version includes no more than 0.25 wt. % Mg. In another embodiment, the second version includes no more than 0.24 wt. % Mg. In yet another embodiment, the second version includes no more than 0.23 wt. % Mg.

[0030] Various embodiments of the second version of the new 2xxx series alloy are presented below.

TABLE 2a. Illustrative alloys according to version two (percentage by weight)

Alloy Cu Li Zn Mn Mg Ag 2V-1 2.5-3.4 0.82-1.20 0.5-2.0 0.10-0.60 0.05-0.35 ≤ 0.22 2V-2 2.6-3.4 0.85-1.15 0.6-1.9 0.15-0.55 0.10-0.30 ≤ 0.005 2V-3 2.6-3.35 0.875-1.15 0.8-1.8 0.20-0.45 0.12-0.275 ≤ 0.005 2V-4 2.7-3.35 0.90-1.10 1.0-1.7 0.20-0.425 0.13-0.25 ≤ 0.005 2V-5 2.7-3.3 0.90-1.10 1.1-1.7 0.225-0.40 0.14-0.25 ≤ 0.005 2V-6 2.8-3.25 0.90-1.075 1.1-1.6 0.225-0.375 0.15-0.24 ≤ 0.005 2V-7 2.8-3.2 0.925-1.05 1.2-1.5 0.25-0.35 0.16-0.24 ≤ 0.005 2V-8 2.85-3.15 0.95-1.05 1.3-1.5 0.27-0.325 0.17-0.23 ≤ 0.005

TABLE 2b. Illustrative alloys according to version two (percentage by weight) (cont.)

Alloy Cu:Zn G.S.C. ^* Fe Si Ti Impurities (each/
Total) The rest ^** 2V-1 ≤ 4.25:1 0.05-0.20 Zr ≤ 0.15 ≤ 0.12 ≤ 0.15 ≤ 0.05 /
≤ 0.15 Al and optional second growth elem. 2V-2 ≤ 4.00:1 0.05-0.18 Zr ≤ 0.12 ≤ 0.10 0.01-0.10 ≤ 0.05 /
≤ 0.15 Al and optional second growth elem. 2V-3 ≤ 4.00:1 0.05-0.16 Zr ≤ 0.10 ≤ 0.08 0.01-0.10 ≤ 0.05 /
≤ 0.15 Al and optional second growth elem. 2V-4 ≤ 3.30:1 0.05-0.15 Zr ≤ 0.08 ≤ 0.06 0.01-0.10 ≤ 0.05 /
≤ 0.15 Al and optional second growth elem. 2V-5 ≤ 2.95:1 0.05-0.15 Zr ≤ 0.08 ≤ 0.06 0.01-0.10 ≤ 0.05 /
≤ 0.15 Al and optional second growth elem. 2V-6 ≤ 2.90:1 0.05-0.15 Zr ≤ 0.08 ≤ 0.06 0.01-0.10 ≤ 0.03 /
≤ 0.10 Al and optional second growth elem. 2V-7 ≤ 2.67:1 0.05-0.15 Zr ≤ 0.08 ≤ 0.06 0.01-0.10 ≤ 0.03 /
≤ 0.10 Al and optional second growth elem. 2V-8 ≤ 2.42:1 0.05-0.15 Zr ≤ 0.06 ≤ 0.04 0.01-0.10 ≤ 0.03 /
≤ 0.10 Al and optional second growth elem.

*GSC=Grain Structure Control

**Optional second growth elem. = optional minor elements

[0031] In one embodiment, the second version includes 2.7-3.3 wt. % Cu, 0.85-1.15 wt. % Li, 1.2-1.6 wt. % Zn, where Cu:Zn (weight ratio) is ≤ 4.25:1, 0.15-0.30 wt. % Mg, (Y1, Y2, Y3, Y4 or Y5) wt. % Mn, ≤ 0.005 wt. % Ag, 0.05-0.15 wt. % Zr, ≤ 0.10 wt. % Fe, ≤ 0.08 wt. % Si, 0.01-0.10 wt. % Ti, the balance being aluminum, optional minor elements and impurities, where Y1 means 0.15-0.40 (i.e. Y1 wt.% Mn means 0.15-0.40 wt.% Mn) where Y2 means 0.15-0.30, where Y3 means 0.15-0.25, where Y4 means 0.20-0.40, and where Y5 means 0.25-0.35.

ii. Product forms

[0032] The new alloys may be useful in a variety of product forms, including, for example, ingot or billet, die-formed products (plate, forged, and extruded products), mold-cast products, additively manufactured products. production, and powder metallurgy products.

[0033] In one embodiment, the new 2xxx series aluminum-based alloy is provided in the form of a thickened formwork product. Thick aluminum alloy die-forming products are those formed by forming that have a cross-sectional thickness of at least 12.7 mm. Products produced by forming may be rolled products, forged products, or extruded products. In one embodiment, the aluminum-based alloy thick-formed product has a thickness of at least 25.4 mm. In another embodiment, the aluminum-based alloy heavy-thickness product produced by forming has a thickness of at least 50.8 mm. In yet another embodiment, the aluminum-based alloy heavy-thickness product produced by forming has a thickness of at least 76.2 mm. In another embodiment, the aluminum-based alloy thickening article produced by forming is characterized by a thickness of at least 101.6 mm. In yet another embodiment, the aluminum-based alloy heavy-thickness product produced by forming has a thickness of at least 126.0 mm. In another embodiment, the aluminum-based alloy heavy-thickness product produced by forming has a thickness of at least 152.4 mm. The improved properties described herein can be obtained for thicker injection molded products having a thickness of no more than 304.8 mm. In one embodiment, the aluminum-based alloy heavy-thickness product produced by forming has a thickness of no more than 254.0 mm. In another embodiment, the aluminum-based alloy heavy-thickness product produced by forming is characterized by a thickness of no more than 203.2 mm. In yet another embodiment, the thick aluminum alloy die-formed product has a thickness of no more than 177.8 mm. As used in this paragraph, thickness means the minimum thickness of the product, with the understanding that some parts of the product may be slightly thicker than the minimum stated.

iii. Pressure treatment

[0034] The new alloy can be formed into a formable shape and a suitable degree of hardness using varying degrees of traditional practices involving direct cooled (DC) casting of the aluminum-based alloy into an ingot form. After traditional stripping, turning or stripping (if necessary) and homogenization, where homogenization can be performed before or after stripping, such ingots can be further processed by subjecting the product to high temperature processing. The article may then optionally be subjected to low temperature processing, optionally annealing, non-polymorphic solution quenching, quenching, and low temperature finishing (eg, by stretching or compressing from 0.5% to 10%). After the final processing stage at low temperature, the product can be subjected to artificial aging. Thus, in some embodiments, products can be produced with hardness grades T3 or T8. In other embodiments, other hardness grades T may be used (eg, any of the hardness grades T1, T2, T4, T5, T6, T7, or T9). T hardness grades are defined in ANSI H35.1 (2009).

iv. Properties

[0035] The new 2xxx series aluminum-lithium alloys typically exhibit an improved combination of at least two of strength, elongation, fracture toughness, and stress corrosion cracking resistance.

[0036] In one embodiment, the new 2xxx series aluminum-lithium alloy has a thickness of at least 80 mm and exhibits a tensile strength (ST) of at least 440 MPa at a hardness grade of T8. In another embodiment, the new 2xxx series aluminum-lithium alloy has a thickness of at least 80 mm and exhibits a tensile strength (ST) of at least 450 MPa at a hardness grade of T8. In yet another embodiment, the new 2xxx series aluminum-lithium alloy has a thickness of at least 80 mm and exhibits a tensile strength (ST) of at least 460 MPa at a hardness grade of T8. In another embodiment, the new 2xxx series aluminum-lithium alloy has a thickness of at least 80 mm and exhibits a tensile strength (ST) of at least 470 MPa at a hardness grade of T8. In yet another embodiment, the new 2xxx series aluminum-lithium alloy has a thickness of at least 80 mm and exhibits a tensile strength (ST) of at least 480 MPa or greater at a hardness grade of T8. The above strength properties can be achieved for products having a thickness of at least 100 mm, or at least 125 mm, or at least 150 mm, or higher.

[0037] In one embodiment, the new 2xxx series aluminum-lithium alloy has a thickness of at least 80 mm and exhibits a plane strain fracture toughness ( _KIC ) (SL) of at least 20 MPa kV . root(m), with hardness class T8. In another embodiment, the new 2xxx series aluminum-lithium alloy has a thickness of at least 80 mm and exhibits a plane strain fracture toughness ( _KIC ) (SL) of at least 21 MPa.sq. root(m), with hardness class T8. In yet another embodiment, the new 2xxx series aluminum-lithium alloy has a thickness of at least 80 mm and exhibits a plane strain fracture toughness ( _KIC ) (SL) of at least 22 MPa.sq. root(m), with hardness class T8. In another embodiment, the new 2xxx series aluminum-lithium alloy has a thickness of at least 80 mm and exhibits a plane strain fracture toughness ( _KIC ) (SL) of at least 23 MPa.sq. root(m), with hardness class T8. In yet another embodiment, the new 2xxx series aluminum-lithium alloy has a thickness of at least 80 mm and exhibits a plane strain fracture toughness ( _KIC ) (SL) of at least 24 MPa.sq. root(m), with hardness class T8. In another embodiment, the new 2xxx series aluminum-lithium alloy has a thickness of at least 80 mm and exhibits a plane strain fracture toughness ( _KIC ) (SL) of at least 25 MPa.sq. root(m), with hardness class T8. In yet another embodiment, the new 2xxx series aluminum-lithium alloy has a thickness of at least 80 mm and exhibits a plane strain fracture toughness ( _KIC ) (SL) of at least 26 MPa.sq. root(m) or more, with hardness class T8. The above fracture toughness properties can be achieved for products having a thickness of at least 100 mm, or at least 125 mm, or at least 150 mm, or higher.

[0038] In one embodiment, the new 2xxx series aluminum-lithium alloy has a thickness of at least 80 mm and exhibits an elongation (ST) of at least 1.5% at a hardness grade of T8. In another embodiment, the new 2xxx series aluminum-lithium alloy has a thickness of at least 80 mm and exhibits an elongation (ST) of at least 2.0% at a hardness grade of T8. In yet another embodiment, the new 2xxx series aluminum-lithium alloy has a thickness of at least 80 mm and exhibits an elongation (ST) of at least 2.5% at a hardness grade of T8. In one embodiment, the new 2xxx series aluminum-lithium alloy has a thickness of at least 80 mm and exhibits an elongation (ST) of at least 3.0% or greater, with a hardness grade of T8. The above elongation properties can be achieved for products having a thickness of at least 100 mm, or at least 125 mm, or at least 150 mm, or higher.

[0039] In one embodiment, the new 2xxx series aluminum-lithium alloy has a thickness of at least 80 mm and has resistance to stress corrosion cracking (defined below) at a hardness grade of T8. The above-mentioned stress corrosion cracking resistance properties can be provided for products having a thickness of at least 100 mm, or at least 125 mm, or at least 150 mm, or higher.

[0040] In one approach, the new 2xxx series aluminum-lithium alloy exhibits a plane strain fracture toughness ( _KIC ) of at least 3.0 MPa·sq. root(m) (MPa·√(m)) greater than that of a standard 2070 series aluminum alloy product where both products are processed to the same product shape, gauge, yield strength and hardness grade. For example, if both the new 2xxx series aluminum-lithium alloy and the 2070 series alloy are produced as a 150 mm thick plate with a T8 hardness grade (with the same amount of tension or compression, for example, with a difference of 0.5 % tension/compression between them), and if both alloys were artificially aged to obtain approximately the same tensile yield strength (for example, with a difference of 5 MPa between them), then in this approach the fracture toughness K _IC of the new aluminum-based alloy and 2xxx series lithium will be at least 3 MPa sq. root(m) is higher than that of the 2070 series alloy. In one embodiment, the new 2xxx series aluminum-lithium alloy exhibits a plane strain fracture toughness ( _KIC ) of at least 4.0 MPa·sq. root(m) greater than a standard 2070 Series aluminum alloy product where both products are processed to the same product shape, gauge, yield strength and hardness grade. In another embodiment, the new 2xxx series aluminum-lithium alloy exhibits a plane strain fracture toughness ( _KIC ) of at least 5.0 MPa·sq. root(m) greater than a standard 2070 Series aluminum alloy product where both products are processed to the same product shape, gauge, yield strength and hardness grade. A standard 2070 series aluminum alloy product has the following nominal (calculated) composition: 3.5 wt. % Cu, 0.30 wt. % Mn, 0.22 wt. % Mg, 0.30 wt. % Zn, 1.15 wt. % Li, 0.30 wt. % Zn, 0.11 wt. % Zr, ≤ 0.04 wt. % Si, ≤ 0.06 wt. % Fe, ≤ 0.03 wt. % Ti, in total no more than 0.10 wt. %, impurities and no more than 0.03 wt. % of each of the impurities, with the remainder being aluminum.

[0041] Although the above properties generally apply to thick plate products, similar properties can also be provided for thick forged products and thick extruded products. Additionally, many of the above properties can be provided in combination, as illustrated by the examples below.

v. Definitions

[0042] Unless otherwise indicated, the following definitions are used in this application.

[0043] "2xxx Series Aluminum Alloys" are aluminum alloy compositions in which copper is the primary alloying element, as defined by the Aluminum Industry Association in International Alloy Designations and Chemical Composition Limits for Wrought Aluminum and Wrought Aluminum Alloys ", page 28 (2015). For the purposes of this patent application, 2xxx series aluminum-based alloy compositions can be used in non-formed products such as die casting, ingot/blank, and additive manufacturing products, among others.

[0044] “Aluminium-based alloy product by forming” means an aluminum-based alloy product that is processed at high temperature after casting, and it includes rolled products (thin sheet or thick sheet), forged products and extruded products.

[0045] “Aluminium-based alloy forged product” means an aluminum-based alloy product produced by forming that has been subjected to either die forging or open forging.

[0046] “Solution quenching without polymorphic transformation” means exposing an aluminum-based alloy to an elevated temperature to introduce the dissolved substance(s) into the solid solution.

[0047] “High temperature processing” means subjecting an aluminum-based alloy article to processing at an elevated temperature, typically at least 250°F.

[0048] “Low temperature processing” means subjecting an aluminum-based alloy article to processing at temperatures that are not considered high temperature processing temperatures, typically below about 250°F (eg, ambient temperature).

[0049] “Artificial aging” means exposing an aluminum-based alloy to elevated temperatures to release dissolved substance(s). Artificial aging may occur in one or multiple stages, which may include varying temperatures and/or exposure times.

[0050] Strength and elongation are measured in accordance with ASTM E8 and B557.

[0051] Fracture toughness is measured in accordance with ASTM E399.

[0052] “Resisting stress corrosion cracking” means that all 2xxx Series aluminum-based alloy product specimens do not fail after 30 days of alternating immersion testing at a total stress of 379 MPa in accordance with ASTM G44/G47, and In this case, at least 5 samples are required for testing. In one embodiment, all samples of a 2xxx series aluminum alloy product fail after 60 days of alternating immersion testing at a total stress of 379 MPa in accordance with ASTM G44/G47, and at least 5 samples are required for testing . In another embodiment, all samples of a 2xxx series aluminum alloy product fail after 90 days of alternating immersion testing at a total stress of 379 MPa in accordance with ASTM G44/G47, and at least 5 samples are required for testing . Specimens for SCC testing are selected such that they are centered on the midplane and oriented in the ST direction relative to the original alloy product.

[0053] As used herein, " additive manufacturing " means "a method of combining materials to form objects based on 3D model data, typically layer by layer, as opposed to subtractive manufacturing techniques" as defined in ASTM F2792-12a entitled " standard terminology in additive manufacturing technology.” Non-limiting examples of additive manufacturing methods useful in the manufacture of aluminum-based alloy products include, for example, DMLS (Direct Metal Laser Sintering), SLM (Selective Laser Melting), SLS (Selective Laser Sintering) and EBM (Electron Beam Melting), among others. Any suitable starting materials made from the above-mentioned new 2xxx series aluminum-based alloys may be used, including one or more powders, one or more wires, one or more sheets, and combinations thereof. In some embodiments, the feedstock for additive manufacturing consists of one or more powders comprising the new 2xxx series aluminum-based alloys. Chip varieties represent particle types. In some embodiments, the additive manufacturing feedstock consists of one or more wires incorporating new 2xxx series aluminum-based alloys. Tape is a type of wire. In some embodiments, the additive manufacturing feedstock consists of one or more sheets comprising new 2xxx series aluminum-based alloys. Foil is a type of sheet.

[0054] Such and other aspects, advantages and novel features of this new technology are set forth in part in the description below and will become apparent to those skilled in the art upon consideration of the following description and figures, or may be discovered by practice of one or more embodiments of the technology, provided in the present invention.

[0055] The figures form part of this description, and include illustrative embodiments of the present invention, and illustrate various objects and features thereof. In addition, any measurements, specifications, etc. shown in the figures are for illustration and not limitation. Accordingly, the specific structural and functional details disclosed herein are not to be interpreted as limiting, but solely as a representative basis for elucidating the various uses of the present invention to one skilled in the art.

[0056] Among those advantages and improvements that have been disclosed, other objects and advantages of the present invention will become apparent from the following description when supported by the accompanying drawings. Detailed embodiments of the present invention are disclosed herein; however, it should be understood that the disclosed embodiments are purely illustrative of the invention, which may be embodied in various forms. In addition, each of the examples given in combination with various embodiments of the present invention is intended to be illustrative and not limiting.

[0057] Throughout the specification and claims, the following terms have the meanings expressly given herein unless the context clearly requires otherwise. The expressions “in one embodiment” and “in some embodiments” as used herein do not necessarily refer to the same embodiment(s), although such a possibility exists. In addition, the expressions “in another embodiment” and “in some embodiments” as used herein do not necessarily refer to a different embodiment, although such a possibility exists. Thus, various embodiments of the present invention can be easily combined without departing from the scope or spirit of the present invention.

[0058] Additionally, when used herein, the term “or” is an inclusive “or” operator and is equivalent to the term “and/or” unless the context clearly requires otherwise (for example, “X1, X2, X3, X4 or X5" does not mean "and/or" in this document, since all of X1 - X5 are unique and different from each other). The term “based on” is non-exclusive and permits reliance on additional factors not described unless the context clearly requires otherwise. Additionally, throughout the specification, singular forms include references to plural forms unless the context clearly requires otherwise. The meaning of "in" includes "in" and "on" unless the context clearly requires otherwise.

[0059] Although several embodiments of the present invention have been described, it should be understood that these embodiments are illustrative and non-limiting only, and that many modifications will be obvious to one of ordinary skill in the art. Moreover, unless the context clearly requires otherwise, the various steps can be carried out in any desired order, and any applicable steps can be added and/or deleted.

BRIEF DESCRIPTION OF GRAPHIC MATERIALS

[0060] FIG. 1-2 are graphs illustrating the characteristics of various aluminum-based alloy products of Example 1.

[0061] FIG. 3 is a graph illustrating the characteristics of various aluminum-based alloy products of Example 2.

DETAILED DESCRIPTION

[0062] Example 1: Testing a Heavy-Plate Product

[0063] Various Al-Li alloys were cast into an ingot and homogenized. The composition of each ingot is shown in Table 3a below. Alloys A and B are the alloys of the present invention. Alloy C and alloy 2070 series are alloys not covered by the present invention. The 2070 series alloy is described, for example, in US Patent Application Publication No. 2012/0225271 from the present applicant.

TABLE 3a. Alloy composition

Alloy Si Fe Cu Mn Mg Zn Li Zr Ti A-1 0.02 0.03 3.57 0.29 0.24 0.94 0.92 0.10 0.02 A-2 0.05 0.03 3.46 0.32 0.27 1.00 0.94 0.10 0.02 B 0.04 0.04 2.96 0.32 0.21 1.42 0.98 0.09 0.02 C 0.05 0.04 3.70 0.33 0.38 0.84 0.97 0.10 0.02 2070 0.02 0.03 3.48 0.30 0.22 0.36 1.13 0.10 0.02

The remainder of each alloy was aluminum, minor elements and impurities, with none of the impurities exceeding 0.05 wt. %, and the total amount of impurities did not exceed 0.15 wt. %. After homogenization, the alloys were high temperature rolled to final gauge, solution quenched without polymorphic transformation, quenched and stretched to approximately 6%. Approximate final gauges are presented in Table 3b below.

TABLE 3b. Alloys and final caliber

Alloy Final caliber
(mm) Final caliber
(inch) A-1(i) 100 3.94 A-1(ii) 150 5.91 A-2(i) 100 3.94 A-2(ii) 150 5.91 B(i) 100 3.94 B(ii) 150 5.91 C(i) 100 3.94 C(ii) 150 5.91 2070(i) 100 3.94 2070(ii) 120 4.72

[0064] Various two-stage artificial aging practices were performed on the alloys, where the first stage was performed at 290°F (143.3°C) for various periods of time shown in Table 4 below, with the second stage being 12 hours at 225° F (107.2°C). Various mechanical properties of aged aluminum alloy plates were measured in accordance with ASTM E8 and B557. The fracture toughness properties of some samples were also measured in accordance with ASTM E399. As shown by the data below and the corresponding FIGS. 1-2, the alloys of the present invention exhibited an improved combination of properties in the transverse height direction.

TABLE 4. Mechanical properties (transverse direction along the height)

Alloy Aging time at 1st stages (hours) TYS(ST)
(MPa) UTS(ST) (MPa) Ext.
(ST) (%) K _IC (SL)
(MPa square root (m)) A-1(i) 25 461.3 526.0 3.2 21.6 A-1(i) thirty 466.1 531.9 3.7 23.1 A-1(i) 50 482.6 543.3 3.1 20.9 A-2(i) 25 466.0 529.0 4.7 21.2 A-2(i) thirty 484.0 543.0 3.8 19.1 B(i) 40 446.1 509.5 3.7 25.9 B(i) 60 451.3 511.6 4.1 24.7 C(i) 25 473.3 538.5 2.8 19.7 C(i) 45 497.5 555.0 2.1 19.2 2070(i) thirty 467.8 535.0 3.3 20.5 2070(i) 50 489.5 548.8 2.4 15.8 A-1(ii) thirty 460.2 515.7 3.1 20.5 A-1(ii) 50 475.4 521.2 2.0 20.4 A-2(ii) 25 442.0 496.0 3.6 24.7 A-2(ii) 25 443.8 495.0 3.0 22.5 A-2(ii) thirty 451.5 504.0 3.0 22.9 B(ii) 40 440.2 484.0 2.8 22.1 B(ii) 60 443.0 489.5 2.5 23.5 C(ii) 25 465.1 517.5 2.7 19.0 C(ii) 45 486.1 534.0 2.2 18.7 2070(ii) (120 mm) thirty 461.3 527.4 3.4 18.2* 2070(ii) (120 mm) 50 482.6 538.1 2.7 16.5*

* = K _Q value.

[0065] At 100 mm thickness, the new alloys typically exhibit improved fracture toughness with equivalent strength. For example, the A-1 alloy of the present invention exhibits a strength of approximately 3 MPa.sq. root(m) greater than that of the 2070 series alloy, with approximately equivalent strength (after 30 hours of aging). The A-2 alloy of the present invention is also an improvement over the 2070 series alloy, and the A-2 alloy is expected to achieve results similar to those of the A-1 alloy if the silicon content of the A-2 alloy is reduced to 0. 02 wt. %. Alloy B of the present invention exhibits very high fracture toughness at reduced strength levels, but is expected to achieve results at least equivalent to A-1 if aged to equivalent strength. The improved properties are even more pronounced at 150 mm, where all the alloys of the present invention exhibit much higher fracture toughness for equivalent strength. It is worth noting that the alloys of the present invention include less magnesium than the non-inventive Alloy C. The alloys of the present invention also have a Cu:Zn ratio (by weight) of no more than 4.25:1, with non-inventive alloys exhibiting higher Cu:Zn ratios. The alloys of the present invention also contain more zinc than alloy C and the non-inventive 2070 series alloy.

[0066] The stress corrosion cracking (SCC) properties of many alloys have been tested in the ST direction and in accordance with ASTM G44/G47. All of the alloys of the present invention, under all aging conditions, have not demonstrated failure at total stress values ranging from 310 MPa to 379 MPa over a period of 30 days after testing, or are not expected to exhibit failure (some alloys still pass the test). In comparison, Alloy C exhibited multiple failures at total stress values ranging from 310 MPa to 379 MPa over a period of 30 days under the same test conditions. This may be a result of the fact that Alloy C includes a large amount of magnesium, which may make Alloy C prone to stress corrosion cracking. Alloy C could be further aged to improve its corrosion properties, but this would reduce its already poor fracture toughness. In comparison, Alloys A and B of the present invention exhibit the proper combination of four properties: strength, elongation, fracture toughness, and stress corrosion cracking resistance.

[0067] Example 2: Additional testing of a plate product

[0068] Three additional Al-Li alloys (all of the present invention) were cast as an ingot and homogenized, their composition shown in Table 5 below.

Table 5. Composition of alloys from example 2

Alloy Si Fe Cu Mn Mg Zn Ag Li Zr Ti 1 0.04 0.04 3.46 0.27 0.26 0.98 -- 0.96 0.10 0.03 2 0.07 0.07 3.63 0.27 0.26 0.97 -- 0.96 0.09 0.02 3 0.06 0.04 3.50 0.26 0.22 0.96 -- 0.97 0.09 0.02

The remainder of each alloy was aluminum, minor elements and impurities, with none of the impurities exceeding 0.05 wt. %, and the total amount of impurities did not exceed 0.15 wt. %. After homogenization, the alloys were high temperature rolled to final gauge, solution quenched without polymorphic transformation, quenched and then stretched to approximately 6%. Then the alloys were subjected to artificial aging at various times and temperatures. Aging conditions are shown in Table 6.

Table 6. Aging conditions for alloys from example 2

Condition First stage Second stage A 20 hours at 290°F 12 hours at 225°F B 30 hours at 290°F C 40 hours at 290°F

The alloys were cooled to room temperature between aging stages.

[0069] The mechanical properties of the alloys were then tested at various thicknesses, the results of which are shown in Table 7 below.

Table 7. Mechanical properties of alloys from example 2

Alloy Final gauge (mm) Aging condition TYS ST (MPa) UTS ST (MPa) Ext. ST
(%) K _IC SL
(MPa·√(m)) 1 59.8 A 455 535 7.8 27.3 B 464 542 7.3 23.9 C 473 548 8.5 22.7 2 60.8 A 454 523 7.8 22.7 B 464 532 7.0 21.8 C 468 538 5.3 21.3 3 107.4 A 443 510 6.0 22.7 B 460 524 5.8 22.0 C 463 523 5.0 22.3

[0070] As shown in FIG. 3, alloys 1-2, characterized by a thickness of approximately 60 mm, exhibit an excellent combination of strength and fracture toughness. Alloy 3 exhibits a strength-impact strength pattern similar to that of the alloys from example 1 at 100 mm.

[0071] The stress corrosion cracking (SCC) properties of many alloys in the ST direction were also tested, as in Example 1, where the total stress was 310 MPa. The results are shown in Table 8 below.

Table 8. SCC test results (number of days tested)

Alloy Final gauge (mm) Aging condition Sample
1 Sample
2 Sample
3 1 59.8 A T T T B T T T 2 60.8 A T T T B T T T 3 107.4 A T T T B T T T

T=still no failure after 20 days of testing.

[0072] Although various embodiments of the present invention have been described in detail, it will be appreciated that modifications and adaptations to these embodiments will be apparent to those skilled in the art. However, it should be clearly understood that such modifications and adaptations are within the spirit and scope of the present invention.

Claims (38)

1. A product made of an aluminum-based alloy of the 2xxx series, obtained by pressure treatment, containing, wt.%: 3.1-3.8 Cu; 0.82-1.20 Li; 0.85-2.0 Zn; 0.10-0.60 Mn; 0.05-0.35 Mg; from 0.05 to 0.50 of at least one grain structure control element, where at least one grain structure control element is selected from the group consisting of Zr, Sc, Cr, V, Hf, other rare earth elements and combinations thereof ; no more than 0.22 Ag; no more than 0.15 Fe; no more than 0.12 Si and no more than 0.15 Ti; the remainder being aluminum, optional minor elements and impurities; wherein minor elements, when present, are included in a total content of not more than 1.0 wt.%; And wherein the 2xxx series aluminum alloy formed product is one of a plate product, an extruded product, or a forged product. 2. The product according to claim 1, where the 2xxx series aluminum-based alloy includes no more than 0.20 wt.% Ag, or no more than 0.15 wt.% Ag, or no more than 0.10 wt.% Ag, or no more than 0.05 wt.% Ag, or not more than 0.01 wt.% Ag, or not more than 0.005 wt.% Ag. 3. The article of claim 1, wherein the 2xxx series aluminum-based alloy comprises at least 0.85 wt% Li, or at least 0.875 wt% Li, or at least 0.900 wt% Li, or at least at least 0.925 wt.% Li, or at least 0.950 wt.% Li. 4. The product according to claim 3, wherein the 2xxx series aluminum-based alloy includes not more than 1.15 wt.% Li, or not more than 1.10 wt.% Li, or not more than 1.075 wt.% Li, or not more than 1.050 wt.% Li, or not more than 1.025 wt.% Li, or not more than 1.000 wt.% Li, or not more than 0.980 wt.% Li. 5. The product of claim 1, wherein the 2xxx series aluminum-based alloy comprises at least 0.125 wt% Mn, or at least 0.15 wt% Mn, or at least 0.175 wt% Mn, or at least at least 0.20 wt.% Mn, or at least 0.225 wt.% Mn, or at least 0.25 wt.% Mn, or at least 0.27 wt.% Mn. 6. The product of claim 5, wherein the 2xxx series aluminum-based alloy includes no more than 0.55 wt.% Mn, or no more than 0.50 wt.% Mn, or no more than 0.45 wt.% Mn, or no more than 0.425 wt.% Mn, or not more than 0.40 wt.% Mn, or not more than 0.375 wt.% Mn, or not more than 0.35 wt.% Mn, or not more than 0.325 wt.% Mn, or not more 0.30 wt.% Mn. 7. The product according to claim 1, where the 2xxx series aluminum-based alloy includes no more than 0.12 wt.% Fe, or no more than 0.10 wt.% Fe, or no more than 0.08 wt.% Fe, or no more than 0.06 wt.% Fe. 8. The product according to claim 1, where the aluminum-based alloy of the 2xxx series includes no more than 0.10 wt.% Si, or no more than 0.08 wt. % Si, or not more than 0.06 wt.% Si, or not more than 0.04 wt.% Si. 9. The article of claim 1, wherein the 2xxx series aluminum-based alloy includes at least 0.005 wt% Ti, or at least 0.010 wt% Ti, or at least 0.015 wt% Ti, or at least 0.020 wt.% Ti. 10. The product of claim 1, wherein the 2xxx series aluminum-based alloy includes no more than 0.10 wt.% Ti, or no more than 0.08 wt.% Ti, or no more than 0.07 wt.% Ti, or no more than 0.06 wt.% Ti, or not more than 0.05 wt.% Ti. 11. The product of claim 1, wherein the grain structure control element is at least Zr, and wherein the alloy includes from 0.05 to 0.20 wt.% Zr. 12. The product of claim 11, wherein the 2xxx series aluminum-based alloy includes at least 0.06 wt% Zr, or at least 0.07 wt% Zr, or at least 0.08 wt% Zr . 13. The product of claim 12, wherein the 2xxx series aluminum-based alloy includes no more than 0.18 wt.% Zr, or no more than 0.16 wt.% Zr, or no more than 0.15 wt.% Zr, or no more than 0.14 wt.% Zr, or not more than 0.13 wt.% Zr. 14. The product according to claim 1, where (wt.% Cu) / (wt.% Zn) is no more than 4.25. 15. The product of claim 1, wherein the 2xxx series aluminum-based alloy comprises at least 0.9 wt% Zn or at least 0.95 wt% Zn. 16. The product of claim 15, wherein the 2xxx series aluminum-based alloy includes no more than 1.8 wt.% Zn, or no more than 1.6 wt.% Zn, or no more than 1.4 wt.% Zn, or no more than 1.3 wt.% Zn, or not more than 1.2 wt.% Zn, or not more than 1.1 wt.% Zn, or not more than 1.05 wt.% Zn. 17. The article of claim 1, wherein the 2xxx series aluminum-based alloy comprises at least 3.2 wt% Cu or at least 3.3 wt% Cu. 18. The product of claim 17, wherein the 2xxx series aluminum-based alloy includes no more than 3.75 wt.% Cu, or no more than 3.7 wt.% Cu, or no more than 3.65 wt.% Cu, or no more than 3.6 wt.% Cu. 19. The product of claim 1, wherein the 2xxx series aluminum-based alloy comprises at least 0.10 wt% Mg, or at least 0.125 wt% Mg, or at least 0.15 wt% Mg, or at least 0.175 wt.% Mg, or at least 0.20 wt.% Mg, or at least 0.21 wt.% Mg, or at least 0.22 wt.% Mg. 20. The product according to claim 19, where the 2xxx series aluminum-based alloy includes not more than 0.325 wt.% Mg, or not more than 0.30 wt.% Mg, or not more than 0.29 wt.% Mg, or not more than 0 .28 wt.% Mg. 21. The product according to claim 1, where (wt.% Cu) / (wt.% Zn) is not more than 4.10, or not more than 4.00, or not more than 3.90, or not more than 3.80, or no more than 3.78. 22. The product according to claim 1, wherein the aluminum-based alloy product obtained by forming has a thickness of at least 12.7 mm. 23. The product according to claim 1, wherein the aluminum-based alloy product obtained by forming has a thickness of at least 101.6 mm. 24. The product according to claim 1, wherein the aluminum-based alloy product obtained by forming has a thickness of at least 152.4 mm. 25. Product according to any one of paragraphs. 22-24, where the aluminum-based alloy product obtained by forming is characterized by a thickness of not more than 203.2 mm.

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