EP3652356B1

EP3652356B1 - High-strength corrosion-resistant aluminum alloy and method of making the same

Info

Publication number: EP3652356B1
Application number: EP17739842.7A
Authority: EP
Inventors: Sazol Kumar DAS; Hany Ahmed; Wei Wen
Original assignee: Novelis Inc Canada
Current assignee: Novelis Inc Canada
Priority date: 2017-07-10
Filing date: 2017-07-10
Publication date: 2022-11-23
Anticipated expiration: 2037-07-10
Also published as: CN110892086B; BR112020000305A2; KR102434921B1; ES2933801T3; CA3069499A1; WO2019013744A1; KR20200028411A; CN110892086A; CA3069499C; JP2020527648A; EP3652356A1; JP7191077B2

Description

FIELD

The present disclosure relates to aluminum alloys and methods of making and processing the same. The present disclosure further relates to aluminum alloys exhibiting high mechanical strength, formability, and corrosion resistance.

BACKGROUND

Recyclable aluminum alloys with high strength are desirable for improved product performance in many applications, including transportation (encompassing without limitation, e.g., trucks, trailers, trains, and marine) applications, electronics applications, and automobile applications. For example, a high-strength aluminum alloy in trucks or trailers would be lighter than conventional steel alloys, providing significant emission reductions that are needed to meet new, stricter government regulations on emissions. Such alloys should exhibit high strength, high formability, and corrosion resistance. Further, it is desirable for such alloys to be formed from recycled content.
However, identifying processing conditions and alloy compositions that will provide such an alloy, particularly with recycled content, has proven to be a challenge. Forming alloys from recycled content may lead to higher zinc (Zn) and copper (Cu) content. Higher Zn alloys traditionally lack strength, and Cu-containing alloys are susceptible to corrosion. US2015316210 A1 discloses an aluminum alloy material for a high-pressure applications.

SUMMARY

Covered embodiments of the invention are defined by the claims, not this summary. This summary is a high-level overview of various aspects of the invention and introduces some of the concepts that are further described in the Detailed Description section below. This summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended to be used in isolation to determine the scope of the claimed subject matter. The subject matter should be understood by reference to appropriate portions of the entire specification, any or all drawings, and each claim.
Described herein are aluminum alloys comprising 0.25 - 1.3 wt. % Si, 1.0 - 2.5 wt. % Mg, 0.5 - 1.5 wt. % Cu, up to 0.2 wt. % Fe, up to 3.0 wt. % Zn, up to 0.15 wt. % Zr, up to 0.5 wt. % Mn, up to 0.15 wt. % impurities, with the remainder as Al, wherein a ratio of Mg to Si (Mg/Si ratio) is from 1.5 to 1 to 3.5 to 1. In some cases, the aluminum alloys can comprise 0.55 - 1.1 wt. % Si, 1.25 - 2.25 wt. % Mg, 0.6 - 1.0 wt. % Cu, 0.05 - 0.17 wt. % Fe, 1.5 - 3.0 wt. % Zn, up to 0.15 wt. % impurities, with the remainder as Al. In some cases, the aluminum alloys can comprise 0.65 - 1.0 wt. % Si, 1.5 - 2.25 wt. % Mg, 0.6 - 1.0 wt. % Cu, 0.12 - 0.17 wt. % Fe, 2.0 - 3.0 wt. % Zn, up to 0.15 wt. % impurities, with the remainder as Al.
The ratio of Mg to Si (i.e., the Mg/Si ratio) is from 1.5 to 1 to 3.5 to 1. For example, the Mg/Si ratio can be from 2.0 to 1 to 3.0 to 1. Optionally, the ratio of Zn to the Mg/Si ratio (i.e., the Zn/(Mg/Si) ratio) is from 0.75 to 1 to 1.4 to 1. For example, the Zn/(Mg/Si) ratio can be from 0.8 to 1 to 1.1 to 1. Optionally, the ratio of Cu to the Zn/(Mg/Si) ratio (i.e., the Cu/[Zn/(Mg/Si)] ratio) is from 0.7 to 1 to 1.4 to 1. For example, the Cu/[Zn/(Mg/Si)] ratio is from 0.8 to 1 to 1.1 to 1.
Also described herein are aluminum alloy products comprising the aluminum alloy as described herein. The aluminum alloy product can have a yield strength of at least 340 MPa (e.g., from 360 MPa to 380 MPa) in the T6 temper. The aluminum alloy products described herein are corrosion resistant and can have an average intergranular corrosion pit depth of less than 100 µm in the T6 temper. The aluminum alloy products also display excellent bendability and can have an r/t (bendability) ratio of 0.5 or less in the T4 temper.
Optionally, the aluminum alloy product comprises one or more precipitates selected from the group consisting of MgZn₂ / Mg(Zn,Cu)₂, Mg₂Si, and Al₄Mg₈Si₇Cu₂. The aluminum alloy product can comprise MgZn₂ / Mg(Zn,Cu)₂ in an average amount of at least 300,000,000 particles per mm², Mg₂Si in an average amount of at least 600,000,000 particles per mm², and/or Al₄Mg₈Si₇Cu₂ in an average amount of at least 600,000,000 particles per mm². In some examples, the aluminum alloy product comprises MgZn₂ / Mg(Zn,Cu)₂, Mg₂Si, and Al₄Mg₈Si₇Cu₂. A ratio of Mg₂Si to Al₄Mg₈Si₇Cu₂ can be from 1:1 to 1.5:1, a ratio of Mg₂Si to MgZn₂ / Mg(Zn,Cu)₂ can be from 1.5:1 to 3:1, and a ratio of Al₄Mg₈Si₇Cu₂ to MgZn₂ / Mg(Zn,Cu)₂ can be from 1.5:1 to 3:1.
Further described herein is a method of producing an aluminum alloy. The method comprises casting an aluminum alloy as described herein to form an aluminum alloy cast product, homogenizing the aluminum alloy cast product, hot rolling the homogenized aluminum alloy cast product to provide a final gauge aluminum alloy, and solution heat treating the final gauge aluminum alloy. The method can further comprise pre-aging the final gauge aluminum alloy. Optionally, the aluminum alloy is cast from a molten aluminum alloy comprising scrap metal, such as from scrap metal containing a 6xxx series aluminum alloy, a 7xxx series aluminum alloy, or a combination of these.

BRIEF DESCRIPTION OF THE FIGURES

Figure 1 is a graph showing an increase in magnesium zinc precipitates with increased magnesium content in aluminum alloys prepared according to certain aspects of the present disclosure.
Figure 2 is a differential scanning calorimetry graph of an aluminum alloy according to certain aspects of the present disclosure.
Figure 3 is a differential scanning calorimetry graph of an aluminum alloy according to certain aspects of the present disclosure.
Figure 4A is a transmission electron microscope micrograph showing precipitate types in an aluminum alloy according to certain aspects of the present disclosure.
Figure 4B is a transmission electron microscope micrograph showing precipitate types in an aluminum alloy according to certain aspects of the present disclosure.
Figure 5 is a graph showing precipitate composition of an aluminum alloy according to certain aspects of the present disclosure.
Figure 6 is a series of optical micrographs showing precipitate formation after various processing steps of an aluminum alloy according to certain aspects of the present disclosure.
Figure 7 is a series of optical micrographs showing precipitate formation after various processing steps of an aluminum alloy according to certain aspects of the present disclosure.
Figure 8 is a series of optical micrographs showing precipitate formation after various processing steps of an aluminum alloy according to certain aspects of the present disclosure.
Figure 9 is a series of optical micrographs showing particle population and grain structure of an aluminum alloy according to certain aspects of the present disclosure.
Figure 10 is a series of optical micrographs showing particle population and grain structure of an aluminum alloy according to certain aspects of the present disclosure.
Figure 11 is a graph showing electrical conductivities of an aluminum alloy according to certain aspects of the present disclosure.
Figure 12 is a graph showing electrical conductivities of an aluminum alloy according to certain aspects of the present disclosure.
Figure 13 is a graph showing yield strength (left histogram in each set), ultimate tensile strength (right histogram in each set), uniform elongation (open circle) and total elongation (open diamond) of aluminum alloys according to certain aspects of the present disclosure.
Figure 14A is a graph showing yield strength (left histogram in each set), ultimate tensile strength (right histogram in each set), uniform elongation (open circle) and total elongation (open diamond) of aluminum alloys according to certain aspects of the present disclosure.
Figure 14B is a graph showing yield strength (left histogram in each set), ultimate tensile strength (right histogram in each set), uniform elongation (open circle) and total elongation (open diamond) of aluminum alloys according to certain aspects of the present disclosure.
Figure 15 is a graph showing yield strength (left histogram in each set), ultimate tensile strength (right histogram in each set), uniform elongation (open circle) and total elongation (open diamond) of aluminum alloys according to certain aspects of the present disclosure.
Figure 16A is a graph showing yield strength (left histogram in each set), ultimate tensile strength (right histogram in each set), uniform elongation (open circle) and total elongation (open diamond) of aluminum alloys according to certain aspects of the present disclosure.
Figure 16B is a graph showing yield strength (left histogram in each set), ultimate tensile strength (right histogram in each set), uniform elongation (open circle) and total elongation (open diamond) of aluminum alloys according to certain aspects of the present disclosure.
Figure 17A is a graph showing yield strength (left histogram in each set), ultimate tensile strength (right histogram in each set), uniform elongation (open circle) and total elongation (open diamond) of aluminum alloys according to certain aspects of the present disclosure.
Figure 17B is a graph showing yield strength (left histogram in each set), ultimate tensile strength (right histogram in each set), uniform elongation (open circle) and total elongation (open diamond) of aluminum alloys according to certain aspects of the present disclosure.
Figure 18A is a graph showing yield strength (left histogram in each set), ultimate tensile strength (right histogram in each set), uniform elongation (open circle) and total elongation (open diamond) of aluminum alloys according to certain aspects of the present disclosure.
Figure 18B is a graph showing yield strength (left histogram in each set), ultimate tensile strength (right histogram in each set), uniform elongation (open circle) and total elongation (open diamond) of aluminum alloys according to certain aspects of the present disclosure.
Figure 19 is a graph showing load displacement data from a 90° bend test of aluminum alloys according to certain aspects of the present disclosure.
Figure 20 is a graph showing load displacement data from a 90° bend test of aluminum alloys according to certain aspects of the present disclosure.
Figure 21 is a graph showing load displacement data from a 90° bend test of an aluminum alloy according to certain aspects of the present disclosure.
Figure 22 is a series of optical micrographs showing corrosion attack in aluminum alloys according to certain aspects of the present disclosure.
Figure 23 is a series of optical micrographs showing corrosion attack in aluminum alloys according to certain aspects of the present disclosure.
Figure 24A is an optical micrograph of an aluminum alloy according to certain aspects of the present disclosure.
Figure 24B is an optical micrograph of an aluminum alloy according to certain aspects of the present disclosure.
Figure 24C is an optical micrograph of an aluminum alloy according to certain aspects of the present disclosure.

DETAILED DESCRIPTION

Described herein are high-strength aluminum alloys and methods of making and processing such alloys. The aluminum alloys described herein exhibit improved mechanical strength, deformability, and corrosion resistance properties. In addition, the aluminum alloys can be prepared from recycled materials. Aluminum alloy products prepared from the alloys described herein include precipitates to enhance strength, such as MgZn₂ / Mg(Zn,Cu)₂, Mg₂Si, and Al₄Mg₈Si₇Cu₂.

Definitions and Descriptions:

The terms "invention," "the invention," "this invention" and "the present invention" used herein are intended to refer broadly to all of the subject matter of this patent application and the claims below.
In this description, reference is made to alloys identified by aluminum industry designations, such as "series" or "6xxx." For an understanding of the number designation system most commonly used in naming and identifying aluminum and its alloys, see "International Alloy Designations and Chemical Composition Limits for Wrought Aluminum and Wrought Aluminum Alloys" or "Registration Record of Aluminum Association Alloy Designations and Chemical Compositions Limits for Aluminum Alloys in the Form of Castings and Ingot," both published by The Aluminum Association.
As used herein, the meaning of "a," "an," or "the" includes singular and plural references unless the context clearly dictates otherwise.
As used herein, a plate generally has a thickness of greater than about 6 mm. For example, a plate may refer to an aluminum product having a thickness of greater than 6 mm, greater than 10 mm, greater than 15 mm, greater than 20 mm, greater than 25 mm, greater than 30 mm, greater than 35 mm, greater than 40 mm, greater than 45 mm, greater than 50 mm, or greater than 100 mm.
As used herein, the term "slab" indicates an alloy thickness in a range of approximately 5 mm to approximately 50 mm. For example, a slab may have a thickness of 5 mm, 10 mm, 15 mm, 20 mm, 25 mm, 30 mm, 35 mm, 40 mm, 45 mm, or 50 mm.
As used herein, a shate (also referred to as a sheet plate) generally has a thickness of from about 4 mm to about 15 mm. For example, a shate may have a thickness of 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm, 11 mm, 12 mm, 13 mm, 14 mm, or 15 mm.
As used herein, a sheet generally refers to an aluminum product having a thickness of less than about 4 mm. For example, a sheet may have a thickness of less than 4 mm, less than 3 mm, less than 2 mm, less than 1 mm, less than 0.5 mm, less than 0.3 mm, or less than 0.1 mm.
Reference is made in this application to alloy temper or condition. For an understanding of the alloy temper descriptions most commonly used, see "American National Standards (ANSI) H35 on Alloy and Temper Designation Systems." An F condition or temper refers to an aluminum alloy as fabricated. An O condition or temper refers to an aluminum alloy after annealing. A T4 condition or temper refers to an aluminum alloy after solution heat treatment (SHT) (i.e., solutionization) followed by natural aging. A T6 condition or temper refers to an aluminum alloy after solution heat treatment followed by artificial aging (AA). A T8x condition or temper refers to an aluminum alloy after solution heat treatment, followed by cold working and then by artificial aging.
As used herein, terms such as "cast metal article," "cast article," and the like are interchangeable and refer to a product produced by direct chill casting (including direct chill co-casting) or semi-continuous casting, continuous casting (including, for example, by use of a twin belt caster, a twin roll caster, a block caster, or any other continuous caster), electromagnetic casting, hot top casting, or any other casting method.
As used herein, the meaning of "room temperature" can include a temperature of from 15 °C to 30 °C, for example 15 °C, 16 °C, 17 °C, 18 °C, 19 °C, 20 °C, 21 °C, 22 °C, 23 °C, 24 °C, 25 °C, 26 °C, 27 °C, 28 °C, 29 °C, or 30 °C.
All ranges disclosed herein are to be understood to encompass any and all subranges subsumed therein. For example, a stated range of "1 to 10" should be considered to include any and all subranges between (and inclusive of) the minimum value of 1 and the maximum value of 10; that is, all subranges beginning with a minimum value of 1 or more, e.g. 1 to 6.1, and ending with a maximum value of 10 or less, e.g., 5.5 to 10.
The following aluminum alloys are described in terms of their elemental composition in weight percentage (wt. %) based on the total weight of the alloy. The remainder of each alloy is aluminum, with a maximum wt. % of 0.15 % for the sum of the impurities.

Alloy Compositions

Described below are novel aluminum alloys. In certain aspects, the alloys exhibit high strength, high formability, and corrosion resistance. The properties of the alloys are achieved due to the elemental compositions of the alloys as well as the methods of processing the alloys to produce aluminum alloy products, including sheets, plates, and shates.
In certain aspects, for a combined effect of strengthening, formability, and corrosion resistance, the alloy has a Cu content of from 0.5 wt. % to 1.5 wt. %, a Zr content of from 0.07 wt. % to 0.12 wt. %, and a controlled Si to Mg ratio, as further described below.
The alloys can have the following elemental composition as provided in Table 1: Table 1

Element Weight Percentage (wt. %)

Si 0.25 - 1.3

Fe 0 - 0.2

Mn 0 - 0.5

Mg 1.0 - 2.5

Cu 0.5 - 1.5

Zn 0-3.0

Zr 0-0.15

Others 0 - 0.05 (each)

0 - 0.15 (total)

Al Remainder

In some examples, the alloys can have the following elemental composition as provided in Table 2.

Table 2

Element	Weight Percentage (wt. %)
Si	0.55 - 1.1
Fe	0.05-0.17
Mn	0.05 - 0.3
Mg	1.25-2.25
Cu	0.6 - 1.0
Zn	1.5 - 3.0
Zr	0.09 - 0.12
Others	0 - 0.05 (each)
Others	0 - 0.15 (total)
Al	Remainder

In some examples, the alloys can have the following elemental composition as provided in Table 3.

Table 3

Element	Weight Percentage (wt. %)
Si	0.65 - 1.0
Fe	0.12-0.17
Mn	0.05 - 0.2
Mg	1.5 - 2.25
Cu	0.6 - 1.0
Zn	2.0 - 3.0
Zr	0.08 - 0.11
Others	0 - 0.05 (each)
Others	0 - 0.15 (total)
Al	Remainder

The disclosed alloy includes silicon (Si) in an amount from 0.25 % to 1.3 % (e.g., from 0.55 % to 1.1 % or from 0.65 % to 1.0 %) based on the total weight of the alloy. For example, the alloy can include 0.25 %, 0.26 %, 0.27 %, 0.28 %, 0.29 %, 0.3 %, 0.31 %, 0.32 %, 0.33 %, 0.34 %, 0.35 %, 0.36 %, 0.37 %, 0.38 %, 0.39 %, 0.4 % ,0.41 %, 0.42 %, 0.43 %, 0.44 %, 0.45 %, 0.46 %, 0.47 %, 0.48 %, 0.49 %, 0.5 %, 0.51 %, 0.52 %, 0.53 %, 0.54 %, 0.55 %, 0.56 %, 0.57 %, 0.58 %, 0.59 %, 0.6 %, 0.61 %, 0.62 %, 0.63 %, 0.64 %, 0.65 %, 0.66 %, 0.67 %, 0.68 %, 0.69 %, 0.7 %, 0.71 %, 0.72 %, 0.73 %, 0.74 %, 0.75 %, 0.76 %, 0.77 %, 0.78 %, 0.79 %, 0.8 %, 0.81 %, 0.82 %, 0.83 %, 0.84 %, 0.85 %, 0.86 %, 0.87 %, 0.88 %, 0.89 %, 0.9 %, 0.91 %, 0.92 %, 0.93 %, 0.94 %, 0.95 %, 0.96 %, 0.97 %, 0.98 %, 0.99 %, 1.0 %, 1.01 %, 1.02 %, 1.03 %, 1.04 %, 1.05 %, 1.06 %, 1.07 %, 1.08 %, 1.09 %, 1.1 %, 1.11 %, 1.12 %, 1.13 %, 1.14 %, 1.15 %, 1.16 %, 1.17 %, 1.18 %, 1.19 %, 1.2 %, 1.21 %, 1.22 %, 1.23 %, 1.24 %, 1.25 %, 1.26 %, 1.27 %, 1.28 %, 1.29 %, or 1.3 % Si. All percentages are expressed in wt. %.
In some examples, the alloy described herein includes iron (Fe) in an amount up to 0.2 % (e.g., from 0.05 % to 0.17 % or from 0.12 % to 0.17 %) based on the total weight of the alloy. For example, the alloy can include 0.01 %, 0.02 %, 0.03 %, 0.04 %, 0.05 %, 0.06 %, 0.07 %, 0.08 %, 0.09 %, 0.1 %, 0.11 %, 0.12 %, 0.13 %, 0.14 %, 0.15 %, 0.16 %, 0.17 %, 0.18 %, 0.19 %, or 0.2 % Fe. In some cases, Fe is not present in the alloy (i.e., 0 %). All percentages are expressed in wt. %.
In some examples, the alloy described herein includes manganese (Mn) in an amount up to 0.5 % (e.g., from 0.05 % to 0.3 % or from 0.05 % to 0.2 %) based on the total weight of the alloy. For example, the alloy can include 0.01 %, 0.02 %, 0.03 %, 0.04 %, 0.05 %, 0.06 %, 0.07 %, 0.08 %, 0.09 %, 0.1 %, 0.11 %, 0.12 %, 0.13 %, 0.14 %, 0.15 %, 0.16 %, 0.17 %, 0.18 %, 0.19 %, 0.2 %, 0.21 %, 0.22 %, 0.23 %, 0.24 %, 0.25 %, 0.26 %, 0.27 %, 0.28 %, 0.29 %, 0.3 %, 0.31 %, 0.32 %, 0.33 %, 0.34 %, 0.35 %, 0.36 %, 0.37 %, 0.38 %, 0.39 %, 0.4 %, 0.41 %, 0.42 %, 0.43 %, 0.44 %, 0.45 %, 0.46 %, 0.47 %, 0.48 %, 0.49 %, or 0.5 % Mn. In some cases, Mn is not present in the alloy (i.e., 0 %). All percentages are expressed in wt. %.
The disclosed alloy includes magnesium (Mg) in an amount from 1.0 % to 2.5 % (e.g., from 1.25 % to 2.25 % or from 1.5 % to 2.25 %) based on the total weight of the alloy. For example, the alloy can include 1.0 %, 1.01 %, 1.02 %, 1.03 %, 1.04 %, 1.05 %, 1.06 %, 1.07 %, 1.08 %, 1.09 %, 1.1 %, 1.11 %, 1.12 %, 1.13 %, 1.14 %, 1.15 %, 1.16 %, 1.17 %, 1.18 %, 1.19 %, 1.2 %, 1.21 %, 1.22 %, 1.23 %, 1.24 %, 1.25 %, 1.26 %, 1.27 %, 1.28 %, 1.29 %, 1.3 %, 1.31 %, 1.32 %, 1.33 %, 1.34 %, 1.35 %, 1.36 %, 1.37 %, 1.38 %, 1.39 %, 1.4 %, 1.41 %, 1.42 %, 1.43 %, 1.44 %, 1.45 %, 1.46 %, 1.47 %, 1.48 %, 1.49 %, 1.5 %, 1.51 %, 1.52 %, 1.53 %, 1.54 %, 1.55 %, 1.56 %, 1.57 %, 1.58 %, 1.59 %, 1.6 %, 1.61 %, 1.62 %, 1.63 %, 1.64 %, 1.65 %, 1.66 %, 1.67 %, 1.68 %, 1.69 %, 1.7 %, 1.71 %, 1.72 %, 1.73 %, 1.74 %, 1.75 %, 1.76 %, 1.77 %, 1.78 %, 1.79 %, 1.8 %, 1.81 %, 1.82 %, 1.83 %, 1.84 %, 1.85 %, 1.86 %, 1.87 %, 1.88 %, 1.89 %, 1.9 %, 1.91 %, 1.92 %, 1.93 %, 1.94 %, 1.95 %, 1.96 %, 1.97 %, 1.98 %, 1.99 %, 2.0 %, 2.01 %, 2.02 %, 2.03 %, 2.04 %, 2.05 %, 2.06 %, 2.07 %, 2.08 %, 2.09 %, 2.1 %, 2.11 %, 2.12 %, 2.13 %, 2.14 %, 2.15 %, 2.16 %, 2.17 %, 2.18 %, 2.19 %, 2.2 %, 2.21 %, 2.22 %, 2.23 %, 2.24 %, 2.25 %, 2.26 %, 2.27 %, 2.28 %, 2.29 %, 2.3 %, 2.31 %, 2.32 %, 2.33 %, 2.34 %, 2.35 %, 2.36 %, 2.37 %, 2.38 %, 2.39 %, 2.4 %, 2.41 %, 2.42 %, 2.43 %, 2.44 %, 2.45 %, 2.46 %, 2.47 %, 2.48 %, 2.49 %, or 2.5 % Mg. All percentages are expressed in wt. %.
The disclosed alloy includes copper (Cu) in an amount from 0.5 % to 1.5 % (e.g., from 0.6 % to 1.0 % or from 0.6 % to 0.9 %) based on the total weight of the alloy. For example, the alloy can include 0.5 %, 0.51 %, 0.52 %, 0.53 %, 0.54 %, 0.55 %, 0.56 %, 0.57 %, 0.58 %, 0.59 %, 0.6 %, 0.61 %, 0.62 %, 0.63 %, 0.64 %, 0.65 %, 0.66 %, 0.67 %, 0.68 %, 0.69 %, 0.7 %, 0.71 %, 0.72 %, 0.73 %, 0.74 %, 0.75 %, 0.76 %, 0.77 %, 0.78 %, 0.79 %, 0.8 %, 0.81 %, 0.82 %, 0.83 %, 0.84 %, 0.85 %, 0.86 %, 0.87 %, 0.88 %, 0.89 %, 0.9 %, 0.91 %, 0.92 %, 0.93 %, 0.94 %, 0.95 %, 0.96 %, 0.97 %, 0.98 %, 0.99 %, 1.0 %, 1.01 %, 1.02 %, 1.03 %, 1.04 %, 1.05 %, 1.06 %, 1.07 %, 1.08 %, 1.09 %, 1.1 %, 1.11 %, 1.12%, 1.13 %, 1.14%, 1.15 %, 1.16%, 1.17%, 1.18%, 1.19%, 1.2%, 1.21 %, 1.22 %, 1.23 %, 1.24 %, 1.25 %, 1.26 %, 1.27 %, 1.28 %, 1.29 %, 1.3 %, 1.31 %, 1.32 %, 1.33 %, 1.34 %, 1.35 %, 1.36 %, 1.37 %, 1.38 %, 1.39 %, 1.4 %, 1.41 %, 1.42 %, 1.43 %, 1.44 %, 1.45 %, 1.46 %, 1.47 %, 1.48 %, 1.49 %, or 1.5 % Cu. All percentages are expressed in wt. %.
In some examples, the alloy described herein includes zinc (Zn) in an amount up to 3.0 % (e.g., from 1.0 % to 3.0 %, from 1.5 % to 3.0 %, or from 2.0 % to 3.0 %) based on the total weight of the alloy. For example, the alloy can include 0.01 %, 0.02 %, 0.03 %, 0.04 %, 0.05 %, 0.06 %, 0.07 %, 0.08 %, 0.09 %, 0.1 %, 0.11 %, 0.12 %, 0.13 %, 0.14 %, 0.15 %, 0.16 %, 0.17 %, 0.18 %, 0.19 %, 0.2 %, 0.21 %, 0.22 %, 0.23 %, 0.24 %, 0.25 %, 0.26 %, 0.27 %, 0.28 %, 0.29 %, 0.3 %, 0.31 %, 0.32 %, 0.33 %, 0.34 %, 0.35 %, 0.36 %, 0.37 %, 0.38 %, 0.39 %, 0.4 %, 0.41 %, 0.42 %, 0.43 %, 0.44 %, 0.45 %, 0.46 %, 0.47 %, 0.48 %, 0.49 %, 0.5 %, 0.51 %, 0.52 %, 0.53 %, 0.54 %, 0.55 %, 0.56 %, 0.57 %, 0.58 %, 0.59 %, 0.6 %, 0.61 %, 0.62 %, 0.63 %, 0.64 %, 0.65 %, 0.66 %, 0.67 %, 0.68 %, 0.69 %, 0.7 %, 0.71 %, 0.72 %, 0.73 %, 0.74 %, 0.75 %, 0.76 %, 0.77 %, 0.78 %, 0.79 %, 0.8 %, 0.81 %, 0.82 %, 0.83 %, 0.84 %, 0.85 %, 0.86 %, 0.87 %, 0.88 %, 0.89 %, 0.9 %, 0.91 %, 0.92 %, 0.93 %, 0.94 %, 0.95 %, 0.96 %, 0.97 %, 0.98 %, 0.99 %, 1.0 %, 1.01 %, 1.02 %, 1.03 %, 1.04 %, 1.05 %, 1.06 %, 1.07 %, 1.08 %, 1.09 %, 1.1 %, 1.11 %, 1.12 %, 1.13 %, 1.14 %, 1.15 %, 1.16 %, 1.17 %, 1.18 %, 1.19 %, 1.2 %, 1.21 %, 1.22 %, 1.23 %, 1.24 %, 1.25 %, 1.26 %, 1.27 %, 1.28 %, 1.29 %, 1.3 %, 1.31 %, 1.32 %, 1.33 %, 1.34 %, 1.35 %, 1.36 %, 1.37 %, 1.38 %, 1.39 %, 1.4 %, 1.41 %, 1.42 %, 1.43 %, 1.44 %, 1.45 %, 1.46 %, 1.47 %, 1.48 %, 1.49 %, 1.5 %, 1.51 %, 1.52 %, 1.53 %, 1.54 %, 1.55 %, 1.56 %, 1.57 %, 1.58 %, 1.59 %, 1.6 %, 1.61 %, 1.62 %, 1.63 %, 1.64 %, 1.65 %, 1.66 %, 1.67 %, 1.68 %, 1.69 %, 1.7 %, 1.71 %, 1.72 %, 1.73 %, 1.74 %, 1.75 %, 1.76 %, 1.77 %, 1.78 %, 1.79 %, 1.8 %, 1.81 %, 1.82 %, 1.83 %, 1.84 %, 1.85 %, 1.86 %, 1.87 %, 1.88 %, 1.89 %, 1.9 %, 1.91 %, 1.92 %, 1.93 %, 1.94 %, 1.95 %, 1.96 %, 1.97 %, 1.98 %, 1.99 %, 2.0 %, 2.01 %, 2.02 %, 2.03 %, 2.04 %, 2.05 %, 2.06 %, 2.07 %, 2.08 %, 2.09 %, 2.1 %, 2.11 %, 2.12 %, 2.13 %, 2.14 %, 2.15 %, 2.16 %, 2.17 %, 2.18 %, 2.19 %, 2.2 %, 2.21 %, 2.22 %, 2.23 %, 2.24 %, 2.25 %, 2.26 %, 2.27 %, 2.28 %, 2.29 %, 2.3 %, 2.31 %, 2.32 %, 2.33 %, 2.34 %, 2.35 %, 2.36 %, 2.37 %, 2.38 %, 2.39 %, 2.4 %, 2.41 %, 2.42 %, 2.43 %, 2.44 %, 2.45 %, 2.46 %, 2.47 %, 2.48 %, 2.49 %, 2.5 %, 2.51 %, 2.52 %, 2.53 %, 2.54 %, 2.55 %, 2.56 %, 2.57 %, 2.58 %, 2.59 %, 2.6 %, 2.61 %, 2.62 %, 2.63 %, 2.64 %, 2.65 %, 2.66 %, 2.67 %, 2.68 %, 2.69 %, 2.7 %, 2.71 %, 2.72 %, 2.73 %, 2.74 %, 2.75 %, 2.76 %, 2.77 %, 2.78 %, 2.79 %, 2.8 %, 2.81 %, 2.82 %, 2.83 %, 2.84 %, 2.85 %, 2.86 %, 2.87 %, 2.88 %, 2.89 %, 2.9 %, 2.91 %, 2.92 %, 2.93 %, 2.94 %, 2.95 %, 2.96 %, 2.97 %, 2.98 %, 2.99 %, or 3.0 % Zn. In some cases, Zn is not present in the alloy (i.e., 0 %). All percentages are expressed in wt. %.
Optionally, zirconium (Zr) can be included in the alloys described herein. In some examples, the alloy includes Zr in an amount up to 0.15 % (e.g., from 0.07 % to 0.15 %, from 0.09 % to 0.12 %, or from 0.08 % to 0.11 %) based on the total weight of the alloy. For example, the alloy can include 0.01 %, 0.02 %, 0.03 %, 0.04 %, 0.05 %, 0.06 %, 0.07 %, 0.08 %, 0.09 %, 0.1 %, 0.11 %, 0.12 %, 0.13 %, 0.14 %, or 0.15 % Zr. In some examples, Zr is not present in the alloys (i.e., 0 %). All percentages are expressed in wt. %. In certain aspects, Zr is added to the above-described compositions to form (Al,Si)₃Zr dispersoids (DO₂₂/DO₂₃ dispersoids) and/or Al₃Zr dispersoids (L1₂ dispersoids).
Optionally, the alloy compositions can further include other minor elements, sometimes referred to as impurities, in amounts of 0.05 % or below, 0.04 % or below, 0.03 % or below, 0.02 % or below, or 0.01 % or below each. These impurities may include, but are not limited to, Ga, V, Ni, Sc, Ag, B, Bi, Li, Pb, Sn, Ca, Cr, Ti, Hf, Sr, or combinations thereof. Accordingly, Ga, V, Ni, Sc, Ag, B, Bi, Li, Pb, Sn, Ca, Cr, Ti, Hf, or Sr may be present in an alloy in amounts of 0.05 % or below, 0.04 % or below, 0.03 % or below, 0.02 % or below, or 0.01 % or below. The sum of all impurities does not exceed 0.15 % (e.g., 0.1 %). All percentages are expressed in wt. %. The remaining percentage of the alloy is aluminum.
Suitable exemplary alloys can include, for example, 1.0 % Si, 2.0 % - 2.25 % Mg, 0.6 % - 0.7 % Cu, 2.5 % - 3.0 % Zn, 0.07 - 0.10 % Mn, 0.14 - 0.17 % Fe, 0.09 - 0.10 % Zr, and up to 0.15 % total impurities, with the remainder Al. In some cases, suitable exemplary alloys can include 0.55 % - 0.65 % Si, 1.5 % Mg, 0.7 % - 0.8 % Cu, 1.55 % Zn, 0.14 - 0.15 % Mn, 0.16 - 0.18 % Fe, and up to 0.15 % total impurities, with the remainder Al. In some cases, suitable exemplary alloys can include 0.65 % Si, 1.5 % Mg, 1.0 % Cu, 2.0 % - 3.0 % Zn, 0.14 - 0.15 % Mn, 0.17 % Fe, and up to 0.15 % total impurities, with the remainder Al.

Alloy Microstructure and Properties

In certain aspects, the Cu, Mg, and Si ratios and Zn content are controlled to enhance corrosion resistance, strength, and formability. The Zn content can control corrosion morphology as described below, by, for example, inducing pitting corrosion and suppressing intergranular corrosion (IGC).
The ratio of Mg to Si (also referred to herein as Mg/Si ratio) is from 1.5:1 to 3.5:1 (e.g., from 1.75:1 to 3.0:1 or from 2.0:1 to 3.0:1). For example, the Mg/Si ratio can be 1.5:1, 1.6:1, 1.7:1, 1.8:1, 1.9:1, 2.0:1, 2.1:1, 2.2:1, 2.3:1, 2.4:1, 2.5:1, 2.6:1, 2.7:1, 2.8:1, 2.9:1, 3.0:1, 3.1:1, 3.2:1, 3.3:1, 3.4:1, 3.5:1, 3.6:1, 3.7:1, 3.8:1, 3.9:1, or 4.0:1. In some non-limiting examples, an aluminum alloy having an Mg/Si ratio of 1.5:1 to 3.5:1 (e.g., from 2.0:1 to 3.0:1) can exhibit high strength and increased formability.
In some non-limiting examples, an aluminum alloy having an Mg/Si ratio of 2.0:1 - 3.0:1 and a Zn content of 2.5 wt. % - 3.0 wt. % can exhibit suppression of IGC typically observed in aluminum alloys having Mg and Si as predominant alloying elements, and instead can induce pitting corrosion. In some cases, pitting corrosion can be favorable over IGC due to a limited attack depth, as IGC can occur along grain boundaries and propagate deeper into the aluminum alloy than pitting corrosion. In some non-limiting examples, a ratio of Zn to the ratio of Mg/Si (i.e., the Zn/(Mg/Si) ratio) can be from 0.75:1 to 1.4:1 (e.g., from 0.8:1 to 1.1:1). For example, the Zn/(Mg/Si) ratio can be 0.75:1, 0.8:1, 0.85:1, 0.9:1, 0.95:1, 1.0:1, 1.05:1, 1.1:1, 1.15:1, 1.2:1, 1.25:1, 1.3:1, 1.35:1, or 1.4:1.
In some still further non-limiting examples, a ratio of Cu to the Zn/(Mg/Si) ratio (i.e., the Cu/[Zn/(Mg/Si)] ratio) can be from 0.7:1 to 1.4:1 (e.g., the Cu/[Zn/(Mg/Si)] ratio can be 0.8:1 to 1.1:1). For example, the ratio of Cu/[Zn/(Mg/Si)] can be 0.7:1, 0.75:1, 0.8:1, 0.85:1, 0.9:1, 0.95:1, 1.0:1, 1.05:1, 1.1:1, 1.15:1, 1.2:1, 1.25:1, 1.3:1, 1.35:1, or 1.4:1. In some non-limiting examples, the ratio of Cu/[Zn/(Mg/Si)] can provide high strength, high deformability, and high corrosion resistance.
In certain aspects, Cu, Si, and Mg can form precipitates in the alloy to result in an alloy with higher strength and enhanced corrosion resistance. These precipitates can form during the aging processes, after solution heat treatment. The Mg and Cu content can provide precipitation of an M/η phase or M phase (e.g., MgZn₂ / Mg(Zn,Cu)₂), resulting in precipitates that can increase strength in the aluminum alloy. During the precipitation process, metastable Guinier Preston (GP) zones can form, which in turn transfer to β" needle shape precipitates (e.g., magnesium silicide, Mg₂Si) that contribute to precipitation strengthening of the disclosed alloys. In certain aspects, addition of Cu leads to the formation of lathe-shaped L phase precipitation (e.g., Al₄Mg₈Si₇Cu₂), which is a precursor of Q' precipitate phase formation and which further contributes to strength.
In some examples, the M phase precipitates, including MgZn₂ and/or Mg(Zn,Cu)₂, can be present in the aluminum alloy in an average amount of at least 300,000,000 particles per square millimeter (mm²). For example, the M phase precipitates can be present in an amount of at least 310,000,000 particles per mm², at least 320,000,000 particles per mm², at least 330,000,000 particles per mm², at least 340,000,000 particles per mm², at least 350,000,000 particles per mm², at least 360,000,000 particles per mm², at least 370,000,000 particles per mm², at least 380,000,000 particles per mm², at least 390,000,000 particles per mm², or at least 400,000,000 particles per mm².
In some examples, the L phase precipitates, including Al₄Mg₈Si₇Cu₂, can be present in the aluminum alloy in an average amount of at least 600,000,000 particles per square millimeter (mm²). For example, the L phase precipitates can be present in an amount of at least 610,000,000 particles per mm², at least 620,000,000 particles per mm², at least 630,000,000 particles per mm², at least 640,000,000 particles per mm², at least 650,000,000 particles per mm², at least 660,000,000 particles per mm², at least 670,000,000 particles per mm², at least 680,000,000 particles per mm², at least 690,000,000 particles per mm², or at least 700,000,000 particles per mm².
In some examples, the β" phase precipitates, including Mg₂Si, can be present in the aluminum alloy in an average amount of at least 600,000,000 particles per square millimeter (mm²). For example, the β" phase precipitates can be present in an amount of at least 610,000,000 particles per mm², at least 620,000,000 particles per mm², at least 630,000,000 particles per mm², at least 640,000,000 particles per mm², at least 650,000,000 particles per mm², at least 660,000,000 particles per mm², at least 670,000,000 particles per mm², at least 680,000,000 particles per mm², at least 690,000,000 particles per mm², at least 700,000,000 particles per mm², at least 710,000,000 particles per mm², at least 720,000,000 particles per mm², at least 730,000,000 particles per mm², at least 740,000,000 particles per mm², or at least 750,000,000 particles per mm².
In some examples, a ratio of the β" phase precipitates (e.g., Mg₂Si) to the L phase precipitates (e.g., Al₄Mg₈Si₇Cu₂) can be from 1:1 to 1.5:1 (e.g., from 1.1:1 to 1.4:1). For example, the ratio of the β" phase precipitates to the L phase precipitates can be 1:1, 1.1:1, 1.2:1, 1.3:1, 1.4:1, or 1.5:1.
In some examples, a ratio of the β" phase precipitates (e.g., Mg₂Si) to the M phase precipitates (e.g., MgZn₂ and/or Mg(Zn,Cu)₂) can be from 1.5:1 to 3:1 (e.g., from 1.6:1 to 2.8:1 or from 2.0:1 to 2.5:1). For example, the ratio of the β" phase precipitates to the M phase precipitates can be 1.5:1, 1.6:1, 1.7:1, 1.8:1, 1.9:1, 2.0:1, 2.1:1, 2.2:1, 2.3:1, 2.4:1, 2.5:1, 2.6:1, 2.7:1, 2.8:1, 2.9:1, or 3.0:1.
In some examples, a ratio of the L phase precipitates (e.g., Al₄Mg₈Si₇Cu₂) to the M phase precipitates (e.g., MgZn₂ and/or Mg(Zn,Cu)₂) can be from 1.5:1 to 3:1 (e.g., from 1.6:1 to 2.8:1 or from 2.0:1 to 2.5:1). For example, the ratio of the L phase precipitates to the M phase precipitates can be 1.5:1, 1.6:1, 1.7:1, 1.8:1, 1.9:1, 2.0:1, 2.1:1, 2.2:1, 2.3:1, 2.4:1, 2.5:1, 2.6:1, 2.7:1, 2.8:1, 2.9:1, or 3.0:1.
The alloys described herein display exceptional mechanical properties, as further provided below. The mechanical properties of the aluminum alloys can be further controlled by various aging conditions depending on the desired use. As one example, the alloy can be produced (or provided) in the T4 temper or the T6 temper. T4 aluminum alloy articles that are solution heat-treated and naturally aged can be provided. These T4 aluminum alloy articles can optionally be subjected to additional aging treatment(s) to meet strength requirements upon receipt. For example, aluminum alloy articles can be delivered in other tempers, such as the T6 temper, by subjecting the T4 alloy material to the appropriate aging treatment as described herein or otherwise known to those of skill in the art. Exemplary properties in exemplary tempers are provided below.
In certain aspects, the aluminum alloy can have a yield strength of at least 340 MPa in the T6 temper. In non-limiting examples, the yield strength can be at least 350 MPa, at least 360 MPa, or at least 370 MPa. In some cases, the yield strength is from 340 MPa to 400 MPa. For example, the yield strength can be from 350 MPa to 390 MPa or from 360 MPa to 380 MPa.
In certain aspects, the aluminum alloy can have an ultimate tensile strength of at least 400 MPa in the T6 temper. In non-limiting examples, the ultimate tensile strength can be at least 410 MPa, at least 420 MPa, or at least 430 MPa. In some cases, the ultimate tensile strength is from 400 MPa to 450 MPa. For example, the ultimate tensile strength can be from 410 MPa to 440 MPa or from 415 MPa to 435 MPa.
In certain aspects, the aluminum alloy has sufficient ductility or toughness to meet a 90° bendability of 1.0 or less in the T4 temper (e.g., 0.5 or less). In certain examples, the r/t bendability ratio is 1.0 or less, 0.9 or less, 0.8 or less, 0.7 or less, 0.6 or less, 0.5 or less, 0.4 or less, 0.3 or less, 0.2 or less, or 0.1 or less, where r is the radius of the tool (die) used and t is the thickness of the material.
In certain aspects, the aluminum alloy exhibits a uniform elongation of greater than or equal to 20 % in the T4 temper and a total elongation of greater than or equal to 30 % in the T4 temper. In certain aspects, the alloys exhibit a uniform elongation of greater than or equal to 22 % and a total elongation of greater than or equal to 35 %. For example, the alloys can exhibit a uniform elongation of 20 % or more, 21 % or more, 22 % or more, 23 % or more, 24 % or more, 25 % or more, 26 % or more, 27 % or more, or 28 % or more. The alloys can exhibit a total elongation of 30 % or more, 31 % or more, 32 % or more, 33 % or more, 34 % or more, 35 % or more, 36 % or more, 37 % or more, 38 % or more, 39 % or more, or 40 % or more.
In certain aspects, the aluminum alloy exhibits a suitable resistance to IGC, as measured by ISO 11846B. For example, the pitting in the aluminum alloys can be completely suppressed or improved, such that the average intergranular corrosion pit depth of an alloy in the T6 temper is less than 100 µm. For example, the average intergranular corrosion pit depth can be less than 90 µm, less than 80 µm, less than 70 µm, less than 60 µm, less than 50 µm, or less than 40 µm.

Methods of Preparing the Aluminum Alloys

In certain aspects, the disclosed alloy composition is a product of a disclosed method. Without intending to limit the disclosure, aluminum alloy properties are partially determined by the formation of microstructures during the alloy's preparation. In certain aspects, the method of preparation for an alloy composition may influence or even determine whether the alloy will have properties adequate for a desired application.

Casting

The alloy described herein can be cast using a casting method. In some non-limiting examples, the aluminum alloy as described herein can be cast from molten aluminum alloy that includes scrap alloys (e.g., from an AA6xxx series aluminum alloy scrap, an AA7xxx series aluminum alloy scrap, or a combination of these). The casting process can include a Direct Chill (DC) casting process. Optionally, the ingot can be scalped before downstream processing. Optionally, the casting process can include a continuous casting (CC) process. The cast aluminum alloy can then be subjected to further processing steps. For example, the processing methods as described herein can include the steps of homogenizing, hot rolling, solution heat treating, and quenching. In some cases, the processing methods can also include a pre-aging step and/or an artificial aging step.

Homogenization

The homogenization step can include heating the ingot prepared from an alloy composition described herein to attain a peak metal temperature (PMT) of about, or at least about, 500 °C (e.g., at least 520 °C, at least 530 °C, at least 540 °C, at least 550 °C, at least 560 °C, at least 570 °C, or at least 580 °C). For example, the ingot can be heated to a temperature of from 500 °C to 600 °C, from 520 °C to 580 °C, from 530 °C to 575 °C, from 535 °C to 570 °C, from 540 °C to 565 °C, from 545 °C to 560 °C, from 530 °C to 560 °C, or from 550 °C to 580 °C. In some cases, the heating rate to the PMT can be 70 °C/hour or less, 60 °C/hour or less, 50 °C/hour or less, 40 °C/hour or less, 30 °C/hour or less, 25 °C/hour or less, 20 °C/hour or less, or 15 °C/hour or less. In other cases, the heating rate to the PMT can be from 10 °C/min to 100 °C/min (e.g., 10 °C/min to 90 °C/min, 10 °C/min to 70 °C/min, 10 °C/min to 60 °C/min, from 20 °C/min to 90 °C/min, from 30 °C/min to 80 °C/min, from 40 °C/min to 70 °C/min, or from 50 °C/min to 60 °C/min).
The ingot is then allowed to soak (i.e., held at the indicated temperature) for a period of time. According to one non-limiting example, the ingot is allowed to soak for up to 6 hours (e.g., from 30 minutes to 6 hours, inclusively). For example, the ingot can be soaked at a temperature of at least 500 °C for 30 minutes, 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, or 6 hours, or anywhere in between.

Hot Rolling

Following the homogenization step, a hot rolling step can be performed to form a hot band. In certain cases, the ingots are laid down and hot-rolled with an exit temperature ranging from 230 °C to 300 °C (e.g., from 250 °C to 300 °C). For example, the hot roll exit temperature can be 230 °C, 235 °C, 240 °C, 245 °C, 250 °C, 255 °C, 260 °C, 265 °C, 270 °C, 275 °C, 280 °C, 285 °C, 290 °C, 295 °C, or 300 °C.
In certain cases, the ingot can be hot rolled to an 4 mm to 15 mm thick gauge (e.g., from 5 mm to 12 mm thick gauge). For example, the ingot can be hot rolled to an 4 mm thick gauge, 5 mm thick gauge, 6 mm thick gauge, 7 mm thick gauge, 8 mm thick gauge, 9 mm thick gauge, 10 mm thick gauge, 11 mm thick gauge, 12 mm thick gauge, 13 mm thick gauge, 14 mm thick gauge, or 15 mm thick gauge. In certain cases, the ingot can be hot rolled to a gauge greater than 15 mm thick (e.g., a plate gauge). In other cases, the ingot can be hot rolled to a gauge less than 4 mm (e.g., a sheet gauge).

Solution Heat Treating

Following the hot rolling step, the hot band can be cooled by air and then solutionized in a solution heat treatment step. The solution heat treating can include heating the final gauge aluminum alloy from room temperature to a temperature of from 520 °C to 590 °C (e.g., from 520 °C to 580 °C, from 530 °C to 570 °C, from 545 °C to 575 °C, from 550 °C to 570 °C, from 555 °C to 565 °C, from 540 °C to 560 °C, from 560 °C to 580 °C, or from 550 °C to 575 °C). The final gauge aluminum alloy can soak at the temperature for a period of time. In certain aspects, the final gauge aluminum alloy is allowed to soak for up to approximately 2 hours (e.g., from 10 seconds to 120 minutes, inclusively). For example, the final gauge aluminum alloy can be soaked at the temperature of from 525 °C to 590 °C for 20 seconds, 25 seconds, 30 seconds, 35 seconds, 40 seconds, 45 seconds, 50 seconds, 55 seconds, 60 seconds, 65 seconds, 70 seconds, 75 seconds, 80 seconds, 85 seconds, 90 seconds, 95 seconds, 100 seconds, 105 seconds, 110 seconds, 115 seconds, 120 seconds, 125 seconds, 130 seconds, 135 seconds, 140 seconds, 145 seconds, 150 seconds, 5 minutes, 10 minutes, 15 minutes, 20 minutes, 25 minutes, 30 minutes, 35 minutes, 40 minutes, 45 minutes, 50 minutes,
55 minutes, 60 minutes, 65 minutes, 70 minutes, 75 minutes, 80 minutes, 85 minutes, 90 minutes, 95 minutes, 100 minutes, 105 minutes, 110 minutes, 115 minutes, or 120 minutes, or anywhere in between.

Quenching

In certain aspects, the final gauge aluminum alloy can then be cooled to a temperature of 35 °C at a quench speed that can vary between 50 °C/s to 400 °C/s in a quenching step that is based on the selected gauge. For example, the quench rate can be from 50 °C/s to 375 °C/s, from 60 °C/s to 375 °C/s, from 70 °C/s to 350 °C/s, from 80 °C/s to 325 °C/s, from 90 °C/s to 300 °C/s, from 100 °C/s to 275 °C/s, from 125 °C/s to 250 °C/s, from 150 °C/s to 225 °C/s, or from 175 °C/s to 200 °C/s.
In the quenching step, the final gauge aluminum alloy is rapidly quenched with a liquid (e.g., water) and/or gas or another selected quench medium. In certain aspects, the final gauge aluminum alloy can be rapidly quenched with water.

Pre-Aging

Optionally, a pre-aging step can be performed. The pre-aging step can include heating the final gauge aluminum alloy after the quenching step to a temperature of from 100 °C to 160 °C (e.g., from 105 °C to 155 °C, 110 °C to 150 °C, 115 °C to 145 °C, 120 °C to 140 °C, or 125 °C to 135 °C). In certain aspects, the aluminum alloy sheet, plate, or shate is allowed to soak for up to approximately three hours (e.g., for up to 10 minutes, for up to 20 minutes, for up to 30 minutes, for up to 40 minutes, for up to 45 minutes, for up to 60 minutes, for up to 90 minutes, for up to two hours, or for up to three hours).

Aging

The final gauge aluminum alloy can be naturally aged or artificially aged. In some examples, the final gauge aluminum alloy can be naturally aged for a period of time to result in the T4 temper. In certain aspects, the final gauge aluminum alloy in the T4 temper can be artificially aged (AA) at 180 °C to 225 °C (e.g., 185 °C, 190 °C, 195 °C, 200 °C, 205 °C, 210 °C, 215 °C, 220 °C, or 225 °C) for a period of time. Optionally, the final gauge aluminum alloy can be artificially aged for a period from 15 minutes to 8 hours (e.g., 15 minutes, 30 minutes, 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, or 8 hours or anywhere in between) to result in the T6 temper.

Methods of Using

The alloys and methods described herein can be used in automotive, electronics, and transportation applications, such as commercial vehicle, aircraft, or railway applications, or other applications. For example, the alloys could be used for chassis, cross-member, and intra-chassis components (encompassing, but not limited to, all components between the two C channels in a commercial vehicle chassis) to gain strength, serving as a full or partial replacement of high-strength steels. In certain examples, the alloys can be used in T4 and T6 tempers.
In certain aspects, the alloys and methods can be used to prepare motor vehicle body part products. For example, the disclosed alloys and methods can be used to prepare automobile body parts, such as bumpers, side beams, roof beams, cross beams, pillar reinforcements (e.g., A-pillars, B-pillars, and C-pillars), inner panels, side panels, floor panels, tunnels, structure panels, reinforcement panels, inner hoods, or trunk lid panels. The disclosed aluminum alloys and methods can also be used in aircraft or railway vehicle applications, to prepare, for example, external and internal panels. In certain aspects, the disclosed alloys can be used for other specialties applications, such as automotive battery plates/shates.
The described alloys and methods can also be used to prepare housings for electronic devices, including mobile phones and tablet computers. For example, the alloys can be used to prepare housings for the outer casing of mobile phones (e.g., smart phones) and tablet bottom chassis, with or without anodizing. The alloys can also be used to prepare other consumer electronic products and product parts. Exemplary consumer electronic products include mobile phones, audio devices, video devices, cameras, laptop computers, desktop computers, tablet computers, televisions, displays, household appliances, video playback and recording devices, and the like. Exemplary consumer electronic product parts include outer housings (e.g., facades) and inner pieces for the consumer electronic products.
The following examples will serve to further illustrate the present invention without, however, constituting any limitation thereof. On the contrary, it is to be clearly understood that resort may be had to various embodiments, modifications, and equivalents thereof which, after reading the description herein, may suggest themselves to those skilled in the art without departing from the spirit of the invention. During the studies described in the following examples, conventional procedures were followed, unless otherwise stated. Some of the procedures are described below for illustrative purposes.

EXAMPLES

Example 1: Aluminum Alloy Compositions

Tables 4A and 4B below summarize exemplary aluminum alloys and Table 5 provides the properties of the alloys, including yield strength (YS), intergranular corrosion pit depths (IGC), and 90 ° bendability (Bend).

Table 4A

Alloy	Cu	Mg	Mn	Si	Zn	Fe	Zr
1	0.60	0.9 - 1.2	0.19	0.9 - 1.1	< 0.01	0.16 - 0.19	0
2	0.80	1.0	0.17-0.19	1.1	1.5 - 3.0	0.18 - 0.20	0.006
3	0.6 - 0.7	2.0 - 2.25	0.07 - 0.10	1.0	2.5 - 3.0	0.14 - 0.17	0.09 - 0.10
4	0.7 - 0.8	1.5	0.14-0.15	0.55 - 0.65	1.55	0.16 - 0.18	0
5	1.0	1.5	0.14-0.15	0.63 - 0.67	2.0 - 3.0	0.17	0

All expressed in wt. %; total impurities up to 0.15 wt. %; remainder Al.

Table 4B

Alloy	Mg/Si	Zn/(Mg/Si)	Cu/[Zn/(Mg/Si)]
1	0.87 - 1.19	0	0
2	0.97 - 1.1	1.3 - 3.1	0.25 - 0.62
3	2.0 - 2.25	1.1 - 1.5	0.4 - 0.64
4	2.3 - 2.8	0.55 - 0.67	1.04 - 1.4
5	2.2 - 2.4	0.8 - 1.4	0.71 - 1.25

Table 5

Alloy	YS (MPa)	IGC (µm)	Bend (90°)
1	380	300	Fail
2	370	250	Fail
3	340	0	Pass
4	360	200	Fail
5	370	120	Pass

The properties of the alloys were achieved by controlling the ratios of alloying elements. Alloy 1 represents comparative AA6xxx series aluminum alloys exhibiting high strength due to Mg₂Si strengthening precipitates in the aluminum alloy. Alloy 2 represents comparative aluminum alloys exhibiting improved corrosion resistance and a slight decrease in strength upon adding Zn. Alloys 1 and 2, wherein the ratio of Cu/[Zn/(Mg/Si)] does not fall in the range of from 0.7 to 1.4, exhibit significant IGC and failure in a 90° bend test. Alloy 3 represents exemplary aluminum alloys wherein the ratios of Cu/[Zn/(Mg/Si)] are closer to the range of from 0.7 to 1.4 than Alloy 2, exhibiting a decrease in strength with excellent formability and resistance to IGC. Alloy 4 represents exemplary aluminum alloys wherein the ratios of Cu/[Zn/(Mg/Si)] fall within the range of from 0.7 to 1.4, but the ratios of Zn/(Mg/Si) do not fall within a range of from 0.75 to 1.4, exhibiting significant IGC and poor formability, and increased strength when compared to Alloy 3. Alloy 5 represents exemplary aluminum alloys wherein the ratios of Mg/Si, Zn/(Mg/Si), and Cu/[Zn/(Mg/Si)] all fall within the respective ranges, exhibiting high strength, good formability, and good resistance to corrosion.
In addition, exemplary alloys were produced according to the direct chill casting methods described herein. The alloy compositions are summarized in Table 6 below: Table 6

Alloy Si Fe Cu Mn Mg Cr Zn Ti

A 0.65 0.20 1.10 0.15 1.50 0.05 2.0 0.02

B 0.65 0.20 1.10 0.15 1.50 0.05 2.5 0.02

C 0.65 0.20 1.10 0.15 1.50 0.05 3.0 0.02

All expressed in wt. %; remainder Al.

Example 2: Aluminum Alloy Microstructure

Exemplary alloys were produced by direct chill casting and processed according to the methods described herein. As described above, the Mg and Cu content can provide precipitation of an M phase (e.g., MgZn₂ / Mg(Zn, Cu)₂), providing precipitates that can increase strength in the aluminum alloy. Evaluation of the M phase (e.g., MgZn₂) precipitates was performed as a function of Mg content in the exemplary alloys. Figure 1 is a graph showing an increase in Mg content from 1.0 wt. % to 3.0 wt. %. Evident in the graph, a mass fraction of the M phase precipitates (i) increases proportionally with increasing Mg content from 1.0 wt. % to 1.5 wt. %, (ii) remains constant when Mg content is increased from 1.5 wt. % to 2.0 wt. %, (iii) increases proportionally with increasing Mg content from 2.0 wt. % to 2.5 wt. %, and (iv) plateaus with Mg content greater than 2.5 wt. %. The increase in M phase precipitates provides increased strength in the exemplary alloys.
Figure 2 is a graph showing differential scanning calorimetry (DSC) analysis of samples of exemplary Alloy 3 described above (referred to as "H1," "H2," and "H3"). Exothermic peak A indicates precipitate formation in the exemplary alloys and endothermic peak B indicates melting points for the exemplary Alloy 3 samples.
Figure 3 is a graph showing DSC analysis of samples of the exemplary Alloy 5 described above (referred to as "H5," "H6," and "H7"). Exothermic peak A indicates M phase precipitates. Exothermic peak B indicates β" (Mg₂Si) precipitates, showing formation of the strengthening precipitates during an artificial aging step and corresponding to the increase in strength of the exemplary aluminum alloys. Endothermic peak C indicates melting points for the exemplary Alloy 5 samples.
Figure 4A is a transmission electron microscope (TEM) micrograph showing three distinct strengthening precipitate phases, M (MgZn₂) 410, β" (Mg₂Si) 420, and L (Al₄Mg₈Si₇Cu₂) 430. A combination of the three precipitate phases produces a yield strength of about 370 MPa in a T6 temper for a 10 mm gauge aluminum alloy (e.g., Alloy 5). Figure 4B is a TEM micrograph showing Zr-containing precipitate particles 440. Excess Zr in the exemplary alloys can cause coarse needle-like particles to form. The coarse, needle-like Zr-containing precipitate particles 440 can reduce formability of the exemplary alloys. Likewise, too little Zr in the exemplary alloys can fail to provide desired Al₃Zr and/or (Al,Si)₃Zr dispersoids.
Figure 5 is a graph showing the density of each distinct strengthening precipitate phase, M (MgZn₂), L (Al₄Mg₈Si₇Cu₂), and β" (Mg₂Si), in number of precipitate particles per square millimeter (#/mm²) and as a fraction of analyzed area each distinct precipitate phase occupies (%) for Alloy C (see Table 6). The β" precipitates are predominant in both density and occupied area due to their shape. The smaller M and L precipitates occupy less area accordingly, and are present in densities comparable to the β" precipitates.
Figure 6 shows optical micrographs of samples of Alloy 3 as described above. Precipitates were analyzed in as-cast samples (top row), homogenized samples (center row), and hot rolled samples reduced to a 10 mm gauge (bottom row). Eutectic phase precipitates are evident in the as-cast samples. Precipitates did not fully dissolve after homogenization, as shown in the center row of micrographs. Coarse (e.g., greater than about 5 microns) precipitates are evident in the hot rolled samples.
Figure 7 shows optical micrographs of samples of Alloy 3 described above after casting, homogenization, hot rolling to a 10 mm gauge and various solution heat treatment procedures to achieve maximum dissolution of strengthening precipitates during solution heat treatment. Figure 7, panel A shows an Alloy 3 sample solutionized at a temperature of 555 °C for 45 minutes. Figure 7, panel B shows an Alloy 3 sample solutionized at a temperature of 350 °C for 45 minutes, then at a temperature of 500 °C for 30 minutes, and finally at a temperature of 565 °C for 30 minutes. Figure 7, panel C shows an Alloy 3 sample solutionized at a temperature of 350 °C for 45 minutes, then at a temperature of 500 °C for 30 minutes and finally a temperature of 565 °C for 60 minutes. Figure 7, panel D shows an Alloy 3 sample solutionized at a temperature of 560 °C for 120 minutes. Figure 7, panel E shows an Alloy 3 sample solutionized at a temperature of 500 °C for 30 minutes, then at a temperature of 570 °C for 30 minutes. Figure 7, panel F shows an Alloy 3 sample solutionized at a temperature of 500 °C for 30 minutes, then at a temperature of 570 °C for 60 minutes.
Figure 8 shows optical micrographs of samples of Alloy 5 as described above. Precipitates were analyzed in as-cast samples (top row) and homogenized samples (bottom row). Eutectic phase precipitates are evident in the as-cast samples. The precipitates did not fully dissolve after homogenization, as seen in the bottom row of micrographs. Alloy 5, however, exhibited fewer undissolved precipitates as compared to Alloy 3 after homogenization, due to changes in solute levels (e.g., the Mg levels, Si levels, and the Mg/Si ratio).
Figure 9 shows optical micrographs of samples of Alloy 5 described above after hot rolling to a 10 mm gauge. Figure 9, panels A, B, and C show precipitate particles (seen as dark spots) in the exemplary alloy samples after hot rolling to a 10 mm gauge. Figure 9, panels D, E, and F show grain structure after hot rolling the exemplary Alloy 5 samples to a gauge of 10 mm. Grains were not fully recrystallized due to a low hot rolling exit temperature of about 280 °C to about 300 °C.
Figure 10 shows optical micrographs of samples of Alloy 5 described above after hot rolling to a 10 mm gauge, solution heat treating, and natural aging to a T4 temper. Figure 10, panels A, B, and C show very few precipitate particles in the exemplary alloy samples in T4 temper. Figure 10, panels D, E, and F show a fully recrystallized grain structure of the exemplary Alloy 5 samples in T4 temper.
Figure 11 is a graph showing the electrical conductivities of samples of Alloy 3 after casting, homogenization, hot rolling, various solution heat treatment procedures, and artificial aging (AA). The electrical conductivity data (i.e., conductivity as a percent of the International Annealed Copper Standard (%IACS)) show large amounts of precipitation after hot rolling. Various solution heat treatment procedures were evaluated in an attempt to dissolve the precipitates. Solution heat treating was not effective in dissolving precipitates. Furthermore, there was insufficient strengthening precipitate formation during artificial aging to provide optimal strength.
Figure 12 is a graph showing the electrical conductivities of samples of Alloy 5 (referred to as "HR5," "HR6," and "HR7") after casting, homogenization, hot rolling, solution heat treating, and artificial aging. The electrochemical testing data shows large amounts of precipitation after hot rolling. Various solution heat treatment procedures were evaluated in an attempt to dissolve the precipitates. Solution heat treating was effective in dissolving precipitates. Furthermore, artificial aging provided strengthening precipitate formation providing optimal strength.

Example 3: Aluminum Alloy Mechanical Properties

Figure 13 is a graph showing yield strength (left histogram in each set), ultimate tensile strength (right histogram in each set), uniform elongation (open circle), and total elongation (open diamond) for the exemplary Alloys A, B, and C described above. The alloys were solutionized at a temperature of 565 °C for 45 minutes, pre-aged at a temperature of 125 °C for 2 hours, and artificially aged at a temperature of 200 °C for 4 hours to result in a T6 temper. Each alloy exhibited a yield strength greater than 370 MPa, an ultimate tensile strength greater than 425 MPa, a uniform elongation greater than 10 %, and a total elongation greater than 17 %. Increased Zn content did not significantly affect the strength of the exemplary aluminum alloys, but did improve resistance to intergranular corrosion and formability.
Figure 14A is a graph showing yield strength (left histogram in each set), ultimate tensile strength (right histogram in each set), uniform elongation (open circle), and total elongation (open diamond) for samples of the exemplary Alloy 3 in T4 temper (referred to as "H1 T4," "H2 T4," and "H3 T4"). Figure 14B is a graph showing yield strength (left histogram in each set), ultimate tensile strength (right histogram in each set), uniform elongation (open circle), and total elongation (open diamond) for samples of the exemplary Alloy 3 in T6 temper (referred to as "H1 T6," "H2 T6," and "H3 T6").
Figure 15 is a graph showing yield strength (left histogram in each set), ultimate tensile strength (right histogram in each set), uniform elongation (open circle), and total elongation (open diamond) for samples of the exemplary Alloy 3 in T6 temper (referred to as "H1," "H2," and "H3") after various aging procedures, as indicated in the x-axis of the graph. Evident in the graph, a three-step aging procedure was able to produce a high-strength (e.g., 348 MPa) aluminum alloy. Also evident in the graph, aging at low temperatures (e.g., less than 250 °C) was not sufficient to produce strengthening precipitates in the alloy samples.
Figure 16A is a graph showing yield strength (left histogram in each set), ultimate tensile strength (right histogram in each set), uniform elongation (open circle), and total elongation (open diamond) for samples of the exemplary Alloy 4 in T4 temper (referred to as "HR1," "HR2," "HR3," and "HR4"). Figure 16B is a graph showing yield strength (left histogram in each set), ultimate tensile strength (right histogram in each set), uniform elongation (open circle), and total elongation (open diamond) for samples of the exemplary Alloy 4 in T6 temper after various aging procedures (referred to as "HR1," "HR2," "HR3," and "HR4"). Evident in the graph, a maximum strength of 360 MPa was achieved. Also evident in the graph, aging at low temperatures (e.g., less than 250 °C) was not sufficient to produce strengthening precipitates in the alloy samples.
Figure 17A is a graph showing yield strength (left histogram in each set), ultimate tensile strength (right histogram in each set), uniform elongation (open circle), and total elongation (open diamond) for samples of the exemplary Alloy 5 in T4 temper after casting, homogenization, hot rolling to a gauge of 10 mm, solution heat treating, and various quenching techniques (referred to as "HR5," "HR6," and "HR7"). Air cooled samples are referred to as "AC" and water quenched samples are referred to as "WQ" after hot rolling. Figure 17B is a graph showing yield strength (left histogram in each set), ultimate tensile strength (right histogram in each set), uniform elongation (open circle), and total elongation (open diamond) for samples of the exemplary Alloy 5 in T6 temper after casting, homogenization, hot rolling to a gauge of 10 mm, solution heat treating, various quenching techniques, and various aging procedures (referred to as "HR5," "HR6," and "HR7"). Air cooled samples are referred to as "AC" and water quenched samples are referred to as "WQ" after hot rolling. Artificial aging to a T6 temper provided high-strength aluminum alloys having yield strengths of about 360 MPa to about 370 MPa.
Figure 18A is a graph showing yield strength (left histogram in each set), ultimate tensile strength (right histogram in each set), uniform elongation (open circle), and total elongation (open diamond) for samples of the exemplary Alloy 5 in T4 temper (referred to as "HR5," "HR6," and "HR7") after casting, homogenization, hot rolling to a gauge of 10 mm, and solution heat treating. Figure 18B is a graph showing yield strength (left histogram in each set), ultimate tensile strength (right histogram in each set), uniform elongation (open circle), and total elongation (open diamond) for samples of the exemplary Alloy 5 in T6 temper (referred to as "HR5," "HR6," and "HR7") after casting, homogenization, hot rolling to a gauge of 10 mm, solution heat treating, and various aging procedures, as indicated in the graph. Artificial aging to a T6 temper provided high-strength aluminum alloys having yield strengths of about 360 MPa to about 370 MPa.
Figure 19 is a graph showing load displacement data for a 90 ° bend test formability of samples of the exemplary Alloy 5 as described above (referred to as "HR5," "HR6," and "HR7"). Samples tested in a direction longitudinal to a rolling direction are indicated by "-L," and sample tested in a transverse direction to the rolling direction are indicated by "-T." Alloy 5 was subjected to casting, homogenization, hot rolling to a gauge of 10 mm, solution heat treating, and natural aging for one week to provide Alloy 5 samples in T4 temper. Samples were subjected to a 90° bend test and load displacement (left axis) and maximum load (right axis) were recorded.
Figure 20 is a graph showing load displacement data for a 90 ° bend test formability of samples of the exemplary Alloy 5 as described above (referred to as "HR5," "HR6," and "HR7"). Samples tested in a direction longitudinal to a rolling direction are indicated by "-L," and sample tested in a transverse direction to the rolling direction are indicated by "-T." Alloy 5 was subjected to casting, homogenization, hot rolling to a gauge of 10 mm, solution heat treating, pre-aging at a temperature of 125 °C for 2 hours (referred to as "PX") and natural aging for one week to provide Alloy 5 samples in T4 temper. Samples were subjected to a 90° bend test and load displacement (left axis) and maximum load (right axis) were recorded.
Figure 21 is a graph showing load displacement data for a 90 ° bend test formability of samples of the exemplary Alloy 5 as described above. The sample tested in a direction longitudinal to a rolling direction is indicated by "-L" and the sample tested in a transverse direction to the rolling direction is indicated by "-T." The samples were subjected to casting, homogenization, hot rolling to a gauge of 10 mm, solution heat treating, pre-aging at a temperature of 125 °C for 2 hours and natural aging for one month to provide Alloy 5 samples in T4 temper. The samples were subjected to a 90° bend test and load displacement (left axis) and maximum load (right axis) were recorded. There was no noticeable change in formability from one week of natural aging to one month of natural aging with pre-aging employed during production.
Figure 22 shows optical micrographs showing the effects of corrosion testing on alloys described above. The alloys were subjected to corrosion testing according to ISO standard 11846B (e.g., 24 hour immersion in a solution containing 3.0 wt. % sodium chloride (NaCl) and 1.0 volume % hydrochloric acid (HCl) in water). Figure 22, panel A, and Figure 22, panel B show effects of corrosion testing in comparative Alloy 2 described above. Corrosion morphology is an intergranular corrosion (IGC) attack. Figure 22, panels C, D, and E show the effects of corrosion testing in exemplary Alloy 3 as described above. Corrosion morphology is a pitting attack. A pitting attack is a more desirable corrosion morphology causing less damage to the alloy and indicating corrosion resistance in the exemplary alloys.
Figure 23 shows optical micrographs showing the effects of corrosion testing on samples of exemplary Alloy 4 as described above. Evident in the micrographs is significant IGC attack due to the composition of Alloy 4, wherein the ratio of Cu/[Zn/(Mg/Si)] is within the range of from 0.7 to 1.4, but the ratio of Zn/(Mg/Si) is not within the range of from 0.75 to 1.4, resulting in significant IGC attack.
Figures 24A, 24B, and 24C are optical micrographs showing the results of corrosion testing on the exemplary alloys described above. Figure 24A shows intergranular corrosion (IGC) attack in Alloy A. Figure 24B shows intergranular corrosion attack in Alloy B. Figure 24C shows intergranular corrosion attack in Alloy C. Evident in Figures 24A, 24B, and 24C, increasing Zn content changes corrosion morphology from IGC to pitting, and corrosion attack depth is decreased from about 150 µm (Alloy A, Figure 24A) to less than 100 µm (Alloy C, Figure 24C).
Various embodiments of the invention have been described in fulfillment of the various objectives of the invention. It should be recognized that these embodiments are merely illustrative of the principles of the present invention.

Claims

An aluminum alloy comprising 0.25 - 1.3 wt. % Si, 1.0 - 2.5 wt. % Mg, 0.5 - 1.5 wt. % Cu, up to 0.2 wt. % Fe, up to 3.0 wt. % Zn, up to 0.15 wt. % Zr, up to 0.5 wt. % Mn, up to 0.15 wt. % impurities, with the remainder as Al, wherein a ratio of Mg to Si (Mg/Si ratio) is from 1.5 to 1 to 3.5 to 1.
The aluminum alloy of claim 1, comprising 0.55 - 1.1 wt. % Si, 1.25 - 2.25 wt. % Mg, 0.6 - 1.0 wt. % Cu, 0.05 - 0.17 wt. % Fe, 1.5 - 3.0 wt. % Zn, up to 0.15 wt. % impurities, with the remainder as Al.
The aluminum alloy of claim 1 or 2, comprising 0.65 - 1.0 wt. % Si, 1.5 - 2.25 wt. % Mg, 0.6 - 1.0 wt. % Cu, 0.12 - 0.17 wt. % Fe, 2.0 - 3.0 wt. % Zn, up to 0.15 wt. % impurities, with the remainder as Al.
The aluminum alloy of any one of claims 1-3, comprising Zr and in particular, wherein Zr is present in an amount of from 0.09 - 0.12 wt.%.
The aluminum alloy of any one of claims 1-4, comprising Mn and in particular, wherein Mn is present in an amount of from 0.05 - 0.3 wt.%.
The aluminum alloy of any one of claims 1-5, wherein the Mg/Si ratio is from 2.0 to 1 to 3.0 to 1.
The aluminum alloy of claim 6, wherein a ratio of Zn to the Mg/Si ratio (Zn/(Mg/Si) ratio) is from 0.75 to 1 to 1.4 to 1 and in particular, wherein the Zn/(Mg/Si) ratio is from 0.8 to 1 to 1.1 to 1.
The aluminum alloy of claim 7, wherein a ratio of Cu to the Zn/(Mg/Si) ratio (Cu/[Zn/(Mg/Si)] ratio) is from 0.7 to 1 to 1.4 to 1 and in particular, wherein the Cu/[Zn/(Mg/Si)] ratio is from 0.8 to 1 to 1.1 to 1.
An aluminum alloy product, comprising the aluminum alloy according to any one of claims 1-8.
The aluminum alloy product of claim 9, wherein the aluminum alloy product comprises a yield strength of at least 340 MPa in T6 temper and in particular, wherein the yield strength is from 360 MPa to 380 MPa in T6 temper and/or wherein the aluminum alloy product comprises an average intergranular corrosion pit depth of less than 100 µm in T6 temper and/or wherein the aluminum alloy product comprises an r/t (bendability) ratio of 0.5 or less in T4 temper.
The aluminum alloy product of any one of claims 9 or 10, wherein the aluminum alloy product comprises one or more precipitates selected from the group consisting of MgZn₂ / Mg(Zn,Cu)₂, Mg₂Si, and Al₄Mg₈Si₇Cu₂.
The aluminum alloy product of claim 11, wherein the aluminum alloy product comprises MgZn₂ / Mg(Zn,Cu)₂ in an average amount of at least 300,000,000 particles per mm² and/or wherein the aluminum alloy product comprises Mg₂Si in an average amount of at least 600,000,000 particles per mm² and/or wherein the aluminum alloy product comprises Al₄Mg₈Si₇Cu₂ in an average amount of at least 600,000,000 particles per mm².
The aluminum alloy product of any one of claims 11 or 12, wherein the aluminum alloy product comprises MgZn₂ / Mg(Zn,Cu)₂, Mg₂Si, and Al₄Mg₈Si₇Cu₂.
The aluminum alloy product of claim 13, wherein a ratio of Mg₂Si to Al₄Mg₈Si₇Cu₂ is from 1:1 to 1.5:1 and/or wherein a ratio of Mg₂Si to MgZn₂ / Mg(Zn,Cu)₂ is from 1.5:1 to 3:1 and/or wherein a ratio of Al₄Mg₈Si₇Cu₂ to MgZn₂ / Mg(Zn,Cu)₂ is from 1.5:1 to 3:1.
A method of producing an aluminum alloy, comprising:
casting an aluminum alloy according to any one of claims 1-8 to form an aluminum alloy cast product;

homogenizing the aluminum alloy cast product;

hot rolling to provide a final gauge aluminum alloy; and

solution heat treating the final gauge aluminum alloy.
The method of claim 15, further comprising pre-aging the final gauge aluminum alloy and/or wherein the aluminum alloy is cast from molten aluminum alloy comprising scrap metal and in particular, wherein the scrap metal comprises a 6xxx series aluminum alloy, a 7xxx series aluminum alloy, or a combination of these.