ES3015473T3 - Method of making high strength and low quench sensitive 7xxx series aluminum alloys - Google Patents

Abstract

Methods for manufacturing an aluminum alloy product are described. The method includes heating an aluminum alloy rolled product to an initial temperature between 400°C and 525°C. The aluminum alloy rolled product may include a 7xxx series aluminum alloy. The method also includes holding the aluminum alloy rolled product at the initial temperature or at a temperature below 10°C for a period between 15 seconds and 30 minutes. The method also includes annealing the aluminum alloy rolled product at a cooling rate between 0.5°C/s and 125°C/s, thereby producing a heat-treated aluminum alloy product. The heat-treated aluminum alloy product exhibits a strain ratio between 0.3 and 0.8. The strain ratio is determined according to a standard ASTM G129 or ASTM G139 test method. (Automatic translation with Google Translate, no legal value)

Description

DESCRIPTION

Manufacturing methods for high strength, low quench sensitivity 7xxx series aluminum alloys

Cross-reference with related applications

This application claims the benefit of and priority to U.S. Provisional Application No. 62/706,906, filed September 17, 2020.

Field of the invention

The present disclosure relates generally and more specifically to methods for manufacturing aluminum alloy products having improved intergranular strength and resistance to stress corrosion cracking.

Background of the invention

High-strength aluminum alloys are desirable for use in a variety of applications, such as the automotive and aerospace industries. Exemplary high-strength aluminum alloys include the 7xxx series aluminum alloys. During processing of a 7xxx series aluminum alloy, the alloy may be heat treated followed by quenching to lock in dissolved alloying elements and provide resistance to intergranular and stress corrosion cracking and desirable mechanical properties. If quenching does not occur on an appropriate time scale, the resulting product may be susceptible to intergranular and stress corrosion cracking and/or have inadequate mechanical properties.

The rapid cooling rates required for processing 7xxx series aluminum alloys leave extremely small operating windows between the heat treatment step and the quenching step. This small window means a product made from a 7xxx series aluminum alloy may need to be cooled immediately after the heat treatment step, leaving little or no time for other processing steps, such as hot forming or transferring the hot product between locations. Rapid cooling rates can also be undesirable because they often require specialized equipment and increase processing complexity.

Document US 2017/0081749 A1 is directed to an Al-Zn-Mg alloy sheet comprising, in mass percentage, Zn in a content of 3.0% to 6.0%, Mg in a content of 2.5% to 4.5%, Cu in a content of 0.05% to 0.5%, and wherein, the Zn content [Zn] and the Mg content [Mg] satisfies [Zn] > -0.3[Mg]+4.5, grain boundary precipitates observed with a transmission electron microscope at 60000x magnification have an average composition ratio of Zn to Mg of 0.5 to 3.0 in a microstructure of the sheet subjected to natural aging at room temperature after a solution and cooling treatment, the intergranular precipitates observed with a transmission electron microscope at a total magnification of 60000 have an average composition ratio of Zn to Mg of 1.5 to 3.5 in a microstructure of the sheet subjected to a two-stage artificial aging and a one-stage artificial aging after natural aging at room temperature, wherein the two-stage artificial aging comprises a first-stage heat treatment at a temperature of 70° C. to 100° C. for 2 hours or more, and a second-stage heat treatment at a temperature of 100° C. to 170° C. for 5 hours or more, and the one-stage artificial aging comprises a heat treatment at a temperature of 100° C. to 150° C. for 12 to 36 hours.

Document WO 2019/159810 A1 is directed to a method for manufacturing an aluminum alloy member, wherein the member manufactured from a heat-treatable aluminum alloy material is subjected to a solution heat treatment at 440 to 580 °C followed by a quenching treatment, wherein cooling is carried out at a cooling rate of 10 °C/s or more in a temperature range from the solution heat treatment temperature to at least 100 °C, and finally, the material is held at a holding temperature of -196 °C or higher and 40 °C or lower to suppress natural aging, and then a forming treatment is performed, characterized in that in tensile tests carried out at 20 °C on a specimen of the material before the forming operation, the tensile strength is equal to or less than 465 MPa and the yield strength is equal to or less than 295 MPa.

EP3 521 466 A1 relates to a 7xxx aluminium alloy comprising 4 - 15 wt. % Zn, 0.1 - 3.5 wt. % Cu, 1.0 - 4.0 wt. % Mg, 0.05 - 0.50 wt. % Fe, 0.05 - 0.30 wt. % Si, 0.05 - 0.25 wt. % Zr, up to 0.25 wt. % Mn, up to 0.20 wt. % Cr, up to 0.15 wt. % Ti, up to 0.15 wt. % impurities, the balance being Al, and optionally further comprising up to 0.20 % of one or more of the following elements Mo, Nb, Be, B, Co, Sn, Sr, V, In, Hf, Ag, Sc and Ni and/or optionally up to 0.10% of a rare earth element selected from the group consisting of Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu.

Compendium

The term embodiment and similar terms are intended to refer broadly to all subject matter of this disclosure.

and the claims below. It should be understood that statements containing these terms do not

limit the subject matter described herein or limit the meaning or scope of the claims below. Embodiments of the present disclosure covered herein are defined by the claims below.

below, not by this brief description. This brief description is a high-level overview of several aspects

of the disclosure and introduces some of the concepts that are further described in the detailed description section below. This brief summary description 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 the appropriate portions of the entire specification.

of this description, any or all drawings and each claim.

The invention is defined in the appended claims. Alloy products are described herein.

of rolled aluminum and methods of manufacturing aluminum alloy products that have insensitivity to rapid quenching and improved strength values. The methods of making products of

Aluminum alloy products include heating a rolled aluminum alloy product. The rolled aluminum alloy product includes a 7xxx series aluminum alloy product having a temperature of 4.00% by weight to

15.00% by weight of Zn, from 0.30% by weight to 2.50% by weight of Cu, from 1.60% by weight to 2.60% by weight of

Mg, from 0.10% by weight to 0.25% by weight of Fe, from 0.07% by weight to 0.15% by weight of Si, from 0.09% by weight

at 0.15% by weight Zr, from 0.02% by weight to 0.05% by weight Mn, from 0.03% by weight to 0.05% by weight Cr, from

0.003% by weight to 0.035% by weight Ti, and remainder Al, with a maximum of 0.15% by weight for the sum of all impurities, or having from 4.00% by weight to 15.00% by weight Zn, from 0.20% by weight to 2.10% by weight Cu,

2.20% by weight to 2.40% by weight Mg, 0.18% by weight to 0.23% by weight Fe, 0.09% by weight to 0.12% by weight

weight of Si, from 0.05% by weight to 0.15% by weight of Zr, from 0.04% by weight to 0.09% by weight of Mn, from 0.03%

by weight to 0.09% by weight of Cr, from 0.01% by weight to 0.02% by weight of Ti, up to 0.15% by weight of impurities

and the remainder of Al. The rolled aluminum alloy product further includes up to 0.20% by weight of one or more

more than Mo, Nb, Be, B, Co, Sn, Sr, V, In, Hf, Ag, Sc and Ni.

The methods described herein include heating the aluminum alloy product to a

first temperature from 400 °C to 525 °C. For example, the first temperature can be from 450 °C to 510 °C. In

In some embodiments, the first temperature may be a dissolution temperature. After heating the rolled aluminum alloy product to the first temperature, the rolled aluminum alloy product is held at the first temperature or within 10 °C of the first temperature for a duration of

time from 15 seconds to 30 minutes. The method includes cooling the rolled aluminum alloy product to

a cooling rate of 0.5 °C/s to 125 °C/s to generate a heat-treated aluminum alloy product. In some embodiments, the cooling rate may be 5 °C/s to 125 °C/s, while

that in other embodiments, the cooling rate may be from 10 °C/s to 125 °C/s. Optionally, the cooling rate may be from 5 °C/s to 10 °C/s, from 10 °C/s to 15 °C/s, from 15 °C/s to 20 °C/s, from 20 °C/s to

25 °C/s, from 25 °C/s to 30 °C/s, from 30 °C/s to 35 °C/s, from 35 °C/s to 40 °C/s, from 40 °C/s to

100 °C/s, from 100 °C/s to 105 °C/s, from 105 °C/s to 110 °C/s, from 110 °C/s to 115 °C/s, from 115 °C/s to 120 °C/s or

120 °C/s to 125 °C/s.

In some embodiments, cooling the rolled aluminum alloy product may include a first cooling at a first cooling rate to an intermediate temperature and a second cooling at a second cooling rate to an intermediate temperature.

a second cooling rate to the second temperature. The second cooling rate can

be greater than the first cooling rate. The rolled aluminum alloy product is cooled

until the rolled aluminum alloy product reaches a second temperature of 10°C to 100°C.

Optionally, the second temperature may be an ambient temperature. In some embodiments, cooling the rolled aluminum product may include a die cooling process, a process

water quenching and/or a forced air quenching process. As an example, the first cooling rate may correspond to or occur when the aluminum alloy product is removed

from the heating system, but before the product is introduced into the cooling system (e.g., rapid cooling). The initial temperature drop due to exposure to ambient conditions may be or correspond to the first cooling rate. Optionally, the second cooling may then correspond to the cooling that occurs during an active cooling process,

as a die cooling process.

Heating and cooling of the rolled aluminum alloy product may correspond to a process

of solution heat treatment, in some embodiments. Optionally, the method may further include subjecting the rolled bright alloy product to a hot forming process after heating the rolled aluminum alloy product. In some cases, the method may also include aging the heat-treated aluminum alloy product, such as in a T6 temper or T7 temper. For example, the heat-treated aluminum alloy product may optionally be further heated to a temperature of 100°C to 170°C and held at the temperature for 12 hours to 30 hours. Other aging and tempering processes, practices, and conditions may be used, such as those described in U.S. Patent Application Publication US 2018/0202031.

The heat-treated aluminum alloy product may exhibit desirable and/or improved mechanical properties. For example, the heat-treated aluminum alloy product produced by cooling the rolled aluminum alloy product may exhibit a strain ratio of 0.30 to 0.80. For example, the heat-treated aluminum alloy product may exhibit a strain ratio of 0.375 to 0.425 when the cooling rate is about or less than 125°C/s. The strain rate may be determined according to an ASTM G129 standard test method, such as ASTM G129-00 (2013), Standard Practice for Slow Strain Rate Testing to Evaluate the Susceptibility of Metallic Materials to Environmentally Assisted Cracking, ASTM International, West Conshohocken, PA, 2013, or according to an ASTM G139 standard test method, such as ASTM G139-05 (2015), Standard Test Method for Determining Stress-Corrosion Cracking Resistance of Heat-Treatable Aluminum Alloy Products Using Breaking Load Method, ASTM International, West Conshohocken, PA, 2015. In some embodiments, the heat-treated aluminum alloy product may exhibit an ultimate failure stress of 500 MPa to 650 MPa. For example, the heat-treated aluminum alloy product may exhibit an ultimate tensile strength of 605 MPa to 615 MPa when the cooling rate is about 125°C/s or less. In some embodiments, the heat-treated aluminum etched product may exhibit a yield strength of 400 MPa to 600 MPa. For example, the heat-treated aluminum alloy product may exhibit an ultimate tensile strength of 560 MPa to 580 MPa when the cooling rate is about or less than 125°C/s. In some embodiments, the heat-treated aluminum alloy product may exhibit a uniform elongation of 7.50% to 10.50%. For example, the heat-treated aluminum alloy product may exhibit a uniform elongation of 9.00% to 9.60% when the cooling rate is about or less than 125°C/s. In some embodiments, the heat-treated aluminum alloy product may exhibit a total elongation of 10.00% to 15.00%. For example, the heat-treated aluminum alloy product may exhibit a total elongation of 13.80% to 14.20% when the cooling rate is about or less than 125°C/s. In some embodiments, the heat-treated aluminum alloy product may exhibit precipitate-free zone widths of 10 nm to 110 nm. For example, the heat-treated aluminum alloy product may exhibit precipitate-free zone widths of 10 nm to 13 nm when the cooling rate is about or less than 125°C/s.

The heat-treated aluminum alloy product may also exhibit superior corrosion resistance. The heat-treated aluminum alloy product generated by quenching may exhibit a corrosion depth of 5 pm to 300 pm as determined according to a standard ASTM G110 test method. For example, the heat-treated aluminum alloy product may exhibit a corrosion depth of 5 pm to 150 pm or 25 pm to 50 pm when the cooling rate is about 125 °C/s. In some cases, the corrosion depth may include at least one of pitting corrosion or intergranular corrosion. In some embodiments, the corrosion may include intergranular corrosion when the cooling rate is about 50 °C/s or less. Optionally, the corrosion may or may not include intergranular corrosion when the cooling rate is greater than or about 5 °C/s. Optionally, the mechanical properties and corrosion resistance of the heat-treated aluminum alloy product may exceed those set forth above when subjected to more rapid cooling, but it will be appreciated that cooling at rates less than or about 125°C/s may allow more flexibility in handling and processing the hot aluminum alloy product immediately following heat treatment without the heat-treated aluminum alloy product suffering from poor mechanical properties or corrosion resistance. Thus, by using the aluminum alloy products described herein, the cooling process may be less complex and more forgiving and may simplify heat treating, quenching, stamping, or other processes.

Described herein is a heat-treated aluminum alloy product produced according to the method defined in the claims. The heat-treated aluminum alloy product includes a 7xxx series aluminum alloy product as defined in claim 1. In some embodiments, the heat-treated aluminum alloy product may be a formed aluminum alloy product, a hot-formed aluminum alloy product, and/or in a T6 or T7 temper.

The product may be a heat-treated aluminum alloy product having improved mechanical properties. For example, the heat-treated aluminum alloy product may exhibit a strain ratio of 0.30 to 0.80. For example, the heat-treated aluminum alloy product may exhibit a strain ratio of 0.375 to 0.425 when the cooling rate is less than or approximately 125°C/s. The strain ratio may be determined according to a standard test method ASTM G129 and/or ASTM G139. In some embodiments, the heat-treated aluminum alloy product may exhibit an ultimate tensile strength of 500 MPa to 650 MPa, such as 500 MPa to 510 MPa, 510 MPa to 520 MPa, 520 MPa to 530 MPa, 530 MPa to 540 MPa, 540 MPa to 550 MPa, 550 MPa to 560 MPa, 560 MPa to 570 MPa, 570 MPa to 580 MPa, 580 MPa to 590 MPa, 590 MPa to 600 MPa, 600 MPa to 610 MPa, 610 MPa to 620 MPa, 620 MPa to 630 MPa, 630 MPa to 640 MPa, or 640 MPa to 650 MPa. 650 MPa. For example, heat-treated aluminum alloy products may exhibit ultimate tensile strengths of 605 MPa to 615 MPa when the cooling rate is less than or approximately 125 °C/s. In some embodiments, the heat-treated aluminum alloy product may exhibit a yield strength of 400 MPa to 600 MPa, such as 400 MPa to 410 MPa, 410 MPa to 420 MPa, 420 MPa to 430 MPa, 430 MPa to 440 MPa, 440 MPa to 450 MPa, 450 MPa to 460 MPa, 460 MPa to 470 MPa, 470 MPa to 480 MPa, 480 MPa to 490 MPa, 490 MPa to 500 MPa, 500 MPa to 510 MPa, 510 MPa to 520 MPa, 520 MPa to 530 MPa, 530 MPa to 540 MPa, 540 MPa to 550 MPa. MPa, 550 MPa to 560 MPa, 560 MPa to 570 MPa, 570 MPa to 580 MPa, 580 MPa to 590 MPa, or 590 MPa to 600 MPa. For example, the heat-treated aluminum alloy product may exhibit a creep of 560 MPa to 580 MPa when the cooling rate is less than or about 125 °C/s. In some embodiments, the heat-treated aluminum alloy product may exhibit a uniform elongation of 7.50% to 10.50%, such as 7.50% to 8.00%, 8.00% to 8.50%, 8.50% to 9.00%, 9.00% to 9.50%, 9.50% to 10.00%, or 10.00% to 10.50%. For example, the heat-treated aluminum alloy product may exhibit a uniform elongation of 9.00% to 9.60% when the cooling rate is less than or equal to about 125°C/s. In some embodiments, the heat-treated aluminum alloy product may exhibit a total elongation of 10.00% to 15.00%, e.g., 10.00% to 10.50%, 10.50% to 11.00%, 11.00% to 11.50%, 11.50% to 12.00%, 12.00% to 12.50%, 12.50% to 13.00%, 13.00% to 13.50%, 13.50% to 14.00%, 14.00% to 14.50%, or 14.50% to 15.00%. For example, heat-treated aluminum alloy product may exhibit a total elongation of 13.80% to 14.20% when the cooling rate is less than or about 125°C/s. In some embodiments, the heat-treated aluminum alloy product may exhibit precipitate-free zone widths of 10 nm to 110 nm, such as 10 nm to 11 nm, 11 nm to 12 nm, 12 nm to 13 nm, 13 nm to 14 nm, 14 nm to 15 nm, 15 nm to 20 nm, 20 nm to 25 nm, 25 nm to 30 nm, 30 nm to 35 nm, 35 nm to 40 nm, 40 nm to 45 nm, 45 nm to 50 nm, 50 nm to 55 nm, 55 nm to 60 nm, 60 nm to 65 nm, 65 nm to 70 nm, 70 nm to 75 nm, 75 nm to 80 nm, 80 nm to 85 nm, 90 nm to 95 nm, 95 nm to 100 nm, 100 nm to 105 nm, 105 nm to 110 nm, 110 nm to 115 nm, 115 nm to 120 nm, 120 nm to 125 nm, 130 nm to 135 nm, 135 nm to 140 nm, 140 nm to 145 nm, 145 nm to 150 nm, 150 nm to 155 nm, 155 nm to 160 nm, 160 nm to 165 nm, 165 nm to 170 nm, 170 nm to 175 nm, 175 nm to 180 nm, 180 nm to 185 nm, 185 nm to 190 nm, 190 nm to 195 nm, 200 nm to 200 nm, 200 nm to 205 nm, 200 nm to 210 nm, 210 nm to 215 nm, nm, 85 nm to 90 nm, 90 nm to 95 nm, 95 nm to 100 nm, 100 nm to 105 nm, or 105 nm to 110 nm. For example, the heat-treated aluminum alloy product may exhibit precipitate-free zone widths of 10 nm to 13 nm when the cooling rate is less than or about 125 °C/s.

The product may include a heat-treated aluminum alloy product that has superior corrosion resistance. For example, the heat-treated aluminum alloy product may exhibit a corrosion depth of 5 pm to 300 pm as determined according to an ASTM G110 standard test method, such as 5 pm to 10 pm, 10 pm to 15 pm, 15 pm to 20 pm, 20 pm to 25 pm, 25 pm to 30 pm, 30 pm to 35 pm, 35 pm to 40 pm, 40 pm to 45 pm, 45 pm to 50 pm, 50 pm to 60 pm, 60 pm to 70 pm, 70 pm to 80 pm, 80 pm to 90 pm, 90 pm to 100 pm, 100 pm to 110 pm, 110 pm to 120 pm, 120 pm to 130 pm, 130 pm at 2:40 pm, from 2:40 pm to 3:00 pm, from 3:00 pm to 4:00 pm, from 4:00 pm to 5:00 pm, from 5:00 pm to 6:00 pm, from 6:00 pm to 7:00 pm, from 7:00 pm to 8:00 pm, from 8:00 pm to 9:00 pm, from 9:00 pm to 10:00 pm, from 10:00 pm to 11:00 pm, from 11:00 pm to 12:00 pm, from 12:00 pm to 13:00 pm, from 13:00 pm to 14:00 pm, from 14:00 pm to 15:00 pm, from 15:00 pm to 16:00 pm, from 16:00 pm to 17:00 pm, from 17:00 pm to 18:00 pm, from 18:00 pm to 19:00 pm or from 19:00 pm to 3:00 pm. In some embodiments, the heat-treated aluminum alloy product may exhibit a corrosion depth of 5 pm to 150 pm or 25 pm to 50 pm when the cooling rate is less than or 125 °C/s.

The heat-treated aluminum alloy product is generated by heating a rolled aluminum alloy product to a first temperature. The rolled aluminum alloy product includes a 7xxx series aluminum alloy as defined in claim 1. The rolled aluminum alloy product is heated to a temperature of 400°C to 525°C. The rolled aluminum alloy product is held at the first temperature or within 10°C of the first temperature for a time between 15 seconds and 30 minutes, for example, between 15 seconds and 30 seconds, between 30 seconds and 1 minute, between 1 minute and 5 minutes, between 5 minutes and 10 minutes, between 10 minutes and 15 minutes, between 15 minutes and 20 minutes, between 20 minutes and 25 minutes, or between 25 minutes and 30 minutes. The rolled aluminum alloy product is also cooled at a cooling rate of 0.5°C/s to 125°C/s, such as 0.5°C/s to 1°C/s, 1°C/s to 5°C/s, 5°C/s to 10°C/s, 10°C/s to 25°C/s, 25°C/s to 50°C/s, 50°C/s to 75°C/s, 75°C/s to 100°C/s, or 100°C/s to 125°C/s. The product is produced by the methods described herein.

Automotive and aerospace products are also described herein. An automotive product may incorporate a product as described herein. For example, the automotive product may incorporate a heat-treated aluminum alloy product as described above. An aerospace product may incorporate a product as described herein. For example, the aerospace product may incorporate a heat-treated aluminum alloy product as described above. Optionally, an automotive product may incorporate a product generated according to any of the methods described herein. For example, the automotive product may incorporate a heat-treated aluminum alloy product generated by any of the methods described above. Similarly, an aerospace product may incorporate a product generated according to any of the methods described herein. For example, the aerospace product may incorporate a heat-treated aluminum alloy product generated by any of the methods described above. Other objectives and advantages will become apparent from the following detailed description of non-limiting examples.

Brief description of the figures

The specification refers to the following attached FIGs., in which the use of similar reference numerals in different FIGs. is intended to illustrate similar or analogous components.

FIG. 1A provides a cross-sectional view of a corrosion profile of a quench-sensitive aluminum alloy product cooled at a rate of 550 °C/s.

FIG. 1B provides a cross-sectional view of a corrosion profile of a quench-sensitive aluminum alloy product cooled at a rate of 350 °C/s.

FIG. 1C provides a cross-sectional view of a corrosion profile of a quench-sensitive aluminum alloy product cooled at a rate of 250 °C/s.

FIG. 1D provides a cross-sectional view of a corrosion profile of a quench-sensitive aluminum alloy product cooled at a rate of 5 °C/s.

FIG. 2A provides a cross-sectional view of a corrosion profile of a heat-treated aluminum alloy product cooled at a rate of 550 °C/s in accordance with one embodiment.

FIG. 2B provides a cross-sectional view of a corrosion profile of a heat-treated aluminum alloy product cooled at a rate of 350 °C/s in accordance with one embodiment.

FIG. 2C provides a cross-sectional view of a corrosion profile of a heat-treated aluminum alloy product cooled at a rate of 250 °C/s in accordance with one embodiment.

FIG. 2D provides a cross-sectional view of a corrosion profile of a heat-treated aluminum alloy product cooled at a rate of 5 °C/s in accordance with one embodiment.

FIG. 3A provides a cross-sectional view of a corrosion profile of a heat-treated aluminum alloy product cooled at a rate of 550 °C/s in accordance with another embodiment.

FIG. 3B provides a cross-sectional view of a corrosion profile of a heat-treated aluminum alloy product cooled at a rate of 350 °C/s in accordance with another embodiment.

FIG. 3C provides a cross-sectional view of a corrosion profile of a heat-treated aluminum alloy product cooled at a rate of 250 °C/s in accordance with another embodiment.

FIG. 3D provides a cross-sectional view of a corrosion profile of a heat-treated aluminum alloy product cooled at a rate of 5 °C/s according to another embodiment.

FIG. 4 provides an illustrative graph showing a comparison of corrosion depths at different cooling rates for a quench-sensitive aluminum alloy product versus a heat-treated aluminum alloy product made according to some embodiments.

FIG. 5 provides an illustrative graph showing a comparison of creeps at different cooling rates for a quench-sensitive aluminum alloy product versus a heat-treated aluminum alloy product made according to some embodiments.

FIG. 6 provides an illustrative graph showing a comparison of ultimate fracture stresses at different cooling rates for a quench-sensitive aluminum alloy product versus a heat-treated aluminum alloy product made according to some embodiments.

FIG. 7 provides an illustrative graph showing a comparison of total elongation at different cooling rates for a quench-sensitive aluminum alloy product versus a heat-treated aluminum alloy product made according to some embodiments.

FIG. 8 provides an illustrative graph showing a comparison of strain ratios at different cooling rates for a quench-sensitive aluminum alloy product versus a heat-treated aluminum alloy product made according to some embodiments.

FIG. 9 provides an illustrative graph showing a comparison of precipitate-free zone widths at different cooling rates for a quench-sensitive aluminum alloy product versus a heat-treated aluminum alloy product made according to some embodiments.

FIG. 10A provides an electron micrograph image showing precipitate-free zones formed when a quench-sensitive aluminum alloy product is cooled at a rate of 550°C/s. FIG. 10B provides an electron micrograph image showing precipitate-free zones formed when a quench-sensitive aluminum alloy product is cooled at a rate of 150°C/s. FIG. 10C provides an electron micrograph image showing precipitate-free zones formed when a quench-sensitive aluminum alloy product is cooled at a rate of 5°C/s.

FIG. 11A provides an electron micrograph image showing precipitate-free zones of a heat-treated aluminum alloy product formed when a rolled aluminum alloy product made according to embodiments described herein is cooled at a rate of 550°C/s.

FIG. 11B provides an electron micrograph image showing precipitate-free zones of a heat-treated aluminum alloy product formed when a rolled aluminum alloy product made according to embodiments described herein is cooled at a rate of 150°C/s.

FIG. 11C provides an electron micrograph image showing precipitate-free zones of a heat-treated aluminum alloy product formed when a rolled aluminum alloy product made according to embodiments described herein is cooled at a rate of 5 °C/s.

FIG. 12 provides an overview of a method of manufacturing an aluminum alloy product according to some embodiments.

FIG. 13 provides an illustrative graph showing the temperature profile as a function of time for manufacturing aluminum alloy products according to some embodiments.

Detailed description of the invention

Described herein are aluminum alloy products and methods for manufacturing processed aluminum alloy products to achieve enhanced quench sensitivity. Quench sensitivity commonly refers to the impact of rapid quenching on the properties of a metal product, such as mechanical properties and corrosion resistance. Quenching refers to the rapid cooling of a metal product from a first temperature, such as the heat treatment temperature, to a lower temperature, such as room temperature. During processing, aluminum alloy products are subjected to a heat treatment in which the aluminum alloy product is heated to a first elevated temperature, such as 450°C to 525°C. Aluminum alloy products may be subjected to heat treatments, such as those described in U.S. patent application Ser. No. 15/336,982. One objective of quenching is to preserve a metastable solid solution formed by the heat treatment. When a product is cooled at a sufficient rate from the first temperature to a second temperature, often near or at room temperature, a solid solution can be achieved in which the solutes remain in the alloying solution. Solute retention may be desirable because precipitation of the solute from solution during cooling can lead to localized overaging, loss of grain boundary corrosion resistance, and, importantly, poor response to age hardening treatments. Retention of the solute in solid solution can make the solute atoms available to form homogeneous precipitation zones, which are important for strengthening the metal product during age hardening treatments. Another goal of cooling may be to maintain a desirable number of vacant lattice sites to help promote low-temperature diffusion during the aging stage of precipitation hardening.

Some metal products, such as aluminum alloy products, can be particularly sensitive to solute loss. Particularly during age-hardening treatments, solute loss can affect the resulting properties of an aluminum alloy product. Solute loss refers to solutes that are chemically bonded with other elements, making them unavailable for precipitation by hardening. When cooling rates are not sufficiently rapid, solute atoms are prone to splitting toward grain boundaries, as well as vacancies migrating to disordered regions. This movement of solute atoms is often irreversible and can permanently affect the properties of the metal product. For example, some metal products that are not cooled at a sufficient rate may exhibit higher rates of intergranular corrosion and stress corrosion cracking and have reduced creep, failure stress, and grain elongation. Consequently, the most desirable mechanical properties achievable can generally be associated with high cooling rates.

However, achieving high cooling rates can be expensive, complex, or require time-sensitive processes that minimize the opportunity for additional processing between heat treatment steps and quenching steps. Furthermore, high cooling rates can undesirably affect the properties of a metal product. High cooling rates can also result in distortion and the development of residual stress within the product's microstructure, in some cases. Aluminum alloy products can be prone to distortion during cooling due to aluminum's high coefficient of linear expansion, for example. Aluminum's coefficient of linear expansion is twice that of steel, and thus, during large temperature changes, significant amounts of stress or strain can develop due to thermal expansion or contraction. Consequently, a balance between a cooling rate that sufficiently retains most of the elements and compounds from solution hardening and minimizes distortion and residual stress may be desirable to produce an aluminum alloy product with optimal properties.

One approach to balancing the effects of quenching involves multi-step aging processes. Often, such multi-step aging processes include at least one rapid quenching step. For example, the initial quenching from the first temperature can be rapid to maintain the solid solution. However, multi-step aging processes can be complex, expensive, and time-consuming. Accordingly, as described herein, methods and metal products are provided to achieve desirable properties using only a single-step aging process, despite the use of lower quenching rates. Additionally, the described methods and metal products may exhibit quench insensitivity, resulting in improved mechanical properties, such as enhanced strength values, even at low quenching rates.

In particular, the disclosed methods and techniques can provide quench-insensitive 7xxx series aluminum alloys and products subjected to only a single-step aging process. The quench-insensitive 7xxx series aluminum alloys disclosed herein can have improved resistance to intragranular corrosion cracking and stress corrosion cracking without quenching. Exemplary 7xxx series aluminum alloys for use in the disclosed methods and techniques are described in U.S. Patent Application No. 15/336,982.

Definitions and Descriptions

As used herein, the terms “invention,” “the invention,” “this invention,” and “the present invention” refer to the invention as disclosed in the claims that follow.

Throughout this description, reference is made to alloys identified by AA numbers and/or other related designations such as “series” or “7xxx.” To understand the numerical designation system most commonly used in the naming and identification of 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 Composition Limits for Aluminum Alloys in the Form of Castings and Ingot,” both published by The Aluminum Association.

As used herein, a plate generally has a thickness of greater than about 15 mm. For example, a plate may refer to an aluminum product having a thickness of greater than about 15 mm, greater than about 20 mm, greater than about 25 mm, greater than about 30 mm, greater than about 35 mm, greater than about 40 mm, greater than about 45 mm, greater than about 50 mm, or greater than about 100 mm.

As used herein, a sheet (also referred to as a plate) generally has a thickness of about 4 mm to about 15 mm. For example, a sheet may have a thickness of about 4 mm, about 5 mm, about 6 mm, about 7 mm, about 8 mm, about 9 mm, about 10 mm, about 11 mm, about 12 mm, about 13 mm, about 14 mm, or about 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 about 4 mm, less than about 3 mm, less than about 2 mm, less than about 1 mm, less than about 0.5 mm, or less than about 0.3 mm (e.g., about 0.2 mm).

In this application, reference may be made to the alloy's condition or temper. For more commonly used alloy temper descriptions, see “American National Standards (ANSI) H35 on Alloy and Temper Designation Systems.” An F condition or temper refers to an as-manufactured aluminum alloy. A plus condition or temper refers to an annealed aluminum alloy. An Hxx condition or temper, also referred to herein as an H temper, refers to a non-heat-treatable aluminum alloy after cold rolling, with or without heat treatment (e.g., annealed). Suitable H tempers include HX1, HX2, HX3, HX4, HX5, HX6, HX7, HX8, or HX9. A T1 condition or temper refers to an aluminum alloy quenched from hot working and naturally aged (e.g., to room temperature). A T2 condition or temper refers to an aluminum alloy quenched from hot working, cold worked, and naturally aged. A T3 condition or temper refers to a solution heat-treated, cold-worked, and naturally aged aluminum alloy. A T4 condition or temper refers to a solution heat-treated, naturally aged aluminum alloy. A T5 condition or temper refers to an aluminum alloy quenched from hot working and artificially aged (at elevated temperatures). A T6 condition or temper refers to a solution heat-treated, artificially aged aluminum alloy. A T7 condition or temper refers to a solution heat-treated, artificially over-aged aluminum alloy. A T8x condition or temper refers to a solution heat-treated, cold-worked, and artificially aged aluminum alloy. A T9 condition or temper refers to a solution heat-treated, artificially aged, cold-worked aluminum alloy. A W condition or temper refers to an aluminum alloy after solution heat treatment.

As used herein, the meaning of “ambient temperature” may include a temperature from about 15°C to about 30°C, for example about 15°C, about 16°C, about 17°C, about 18°C, about 19°C, about 20°C, about 21°C, about 22°C, about 23°C, about 24°C, about 25°C, about 26°C, about 27°C, about 28°C, about 29°C, or about 30°C. As used herein, the meaning of “ambient conditions” or “ambient environment” may include temperatures from about room temperature, relative humidity from about 20% to about 100%, and barometric pressure from about 975 millibar (mbar) to about 1050 mbar. For example, relative humidity may be about 20%, about 21%, about 22%, about 23%, about 24%, about 25%, about 26%, about 27%, about 28%, about 29%, about 30%, about 31%, about 32%, about 33%, about 34%, about 35%, about 36%, about 37%, about 38%, about 39%, about 40%, about 41%, about 42%, about 43%, about 44%, about 45%, about 46%, about 47%, about 48%, about 49%, about 50%, about 51%, about 52%, about 53%, about 54%, about 55%, about 56%, about 57%, about 58%, about 59%, or about 60% or about 61% or about 62% or about 63% or about 64% or about 65% or about 66% or about 67% or about 68% or about 69% or about 70% or about 71% or about 72% or about 73% or about 74% or about 75% or about 76% or about 77% or about 78% or about 79% or about 80% or about 81% or about 82% or about 83% or about 84% or about 85% or about 86% or about 87% or about 88% or about 89% or about 90% or about 91% or about 92% or about 93% or about 94% or about 95% or about 96% or about 97% or about 98% or about 99% or about 99% or about 100% or about 101% or about 1 60%, about 61%, about 62%, about 63%, about 64%, about 65%, about 66%, about 67%, about 68%, about 69%, about 70%, about 71%, about 72%, about 73%, about 74%, about 75%, about 76%, about 77%, about 78%, about 79%, about 80%, about 81%, about 82%, about 83%, about 84%, about 85%, about 86%, about 87%, about 88%, about 89%, about 90%, about 91%, about 92%, about 93%, about 94%, about 95%, about 96%, about 97%, about 98%, about 99%

about 975 mbar, about 980 mbar, about 985 mbar, about 990 mbar, about 995 mbar, about 1000 mbar, about 1005 mbar, about 1010 mbar, about 1015 mbar, about 1020 mbar, about 1025 mbar, about 1030 mbar, about 1035 mbar, about 1040 mbar, about 1045 mbar, about 1050 mbar or any point in between.

It should be understood that all ranges described herein encompass any and all subranges included 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, for example, 1 to 6.1, and ending with a maximum value of 10 or less, for example, 5.5 to 10. Unless otherwise stated, the expression “up to” when referring to the amount of an element in the composition means that the element is optional and includes a composition with a zero percentage of that particular element. Unless otherwise stated, all composition percentages are in percent by weight (wt %).

As used herein, the meanings of “a,” “an,” and “the” include both singular and plural references unless the context clearly dictates otherwise.

In the present description, aluminum alloy products and their components may be described in terms of their elemental composition in weight percent (wt%). In each alloy, the remainder is aluminum, with a maximum wt% of 0.15% for the sum of all impurities.

Aluminum alloy products and manufacturing methods of aluminum alloy products

FIGS. 1A, 1B, 1C, and 1D provide cross-sectional views of a corrosion profile for a quench-sensitive aluminum alloy product quenched at various quenching rates. A quench-sensitive aluminum alloy product may be a product produced according to conventional methods and techniques. The corrosion profiles may be generated by subjecting the aluminum alloy product to a heat treatment process, followed by quenching at the indicated rate, and then subjecting the quenched aluminum alloy product to a standard corrosion test for determining or evaluating corrosion resistance, such as American Society for Testing and Materials (ASTM) Standard Test Method G139 for Stress Corrosion Cracking Resistance or ASTM Standard Practice G110 for Evaluating Intergranular Corrosion Resistance of Aluminum Alloys Heat Treatable by Immersion in Sodium Chloride Hydrogen Peroxide Solution. The corrosion profile can be obtained by selecting the tested product and obtaining a cross-sectional micrograph image.

For example, FIGS. 1A-1D show a corrosion profile for a quench-sensitive aluminum alloy product identified as aluminum alloy product 110. Aluminum alloy product 110 may be an AA7075 aluminum alloy product. Other exemplary quench-sensitive aluminum alloy products 110 may include AA7022, AA7185, AA6056, AA7020, AA7049, AA7249, or AA7149. Although the discussion of FIGS. 1A-1D, FIGS. 2A-2D, and FIGS. 3A-3D describe aluminum alloy products, FIGS. and related discussion may also be applicable to other types of metal products, in general.

In embodiments, the cooling sensitivity may be determined based on the cooling rate and the type of corrosion exhibited by the aluminum alloy product after corrosion testing. During corrosion testing of quenched products, they may exhibit various types of corrosion. For example, pitting corrosion may be exhibited in which cavities and holes form, representing material loss within the aluminum alloy. In other examples, intergranular corrosion may be exhibited. Intergranular corrosion, also known as intercrystalline corrosion or interdendritic corrosion, may be characterized as a form of localized corrosion in which grain boundaries and material immediately adjacent to the grain boundaries are attacked. In some cases, the cooling sensitivity may be determined based on the form of corrosion and/or the transition from one form of corrosion to another. For example, the cooling sensitivity may correspond to a change in corrosion morphology, such as a change from pitting corrosion to intergranular corrosion when a product is subjected to various cooling rates. In some cases, the slower an aluminum alloy product can be cooled without exhibiting intergranular corrosion in a corrosion test, the more sensitive to cooling the aluminum alloy product may be. Intergranular corrosion may be more undesirable than pitting corrosion due to its ability to more easily propagate cracks under stress conditions.

As illustrated in FIG. 1A, when a quench-sensitive aluminum alloy product is cooled at a rapid cooling rate of 550°C/s, pitting corrosion 120 may be exhibited in a corrosion test. Pitting corrosion 120 can be identified by localized cavities of material loss of the aluminum alloy product 110. The aluminum alloy product 110 may be quenched using water quenching to achieve the rapid cooling rate of 550°C/s. Water is commonly used to quench aluminum alloy products. Common water quenching methods may include cold water immersion, hot water immersion, boiling water, or water spray. Other frequently used quenching methods also include polyalkylene glycol solutions, air blasts, static air (i.e., maintaining the aluminum alloy product at ambient temperature), liquid nitrogen, quench oils, or salt solutions. Depending on the aluminum alloy product, the desired properties, and the required cooling rates, various cooling methods can be selected.

FIG. 1B illustrates that pitting corrosion 120 may also be exhibited when the aluminum alloy product 110 is cooled at a rate of 350°C/s and subjected to a corrosion test. The corrosion morphology changes between FIG. 1B and FIG. 1C. As shown in the corrosion profile of FIG. 1C, intergranular corrosion 130 may be exhibited when the aluminum alloy product 110 is cooled at a rate of 250°C/s or less and subjected to a corrosion test. Intergranular corrosion 130 can be identified by the formation of localized fracture along the grain boundaries of the aluminum alloy product 110. In corrosion profiles, such as those provided in FIGs. 1A-1D, intergranular corrosion 130 can be identified by slightly more delicate fracture within the volume of the aluminum alloy 110 product as compared to the larger fracture or material loss cavities exhibited by pitting corrosion 120. Intergranular corrosion 130 may also be exhibited when the aluminum alloy 110 product is cooled at a rate of 5 °C/s and subjected to a corrosion test. The change in corrosion morphology from pitting corrosion 120 to intergranular corrosion 130 between cooling rates of 350 °C/s and 250 °C/s may indicate that the aluminum alloy 110 product is quench-sensitive or requires a high cooling rate to achieve intergranular corrosion resistance. Furthermore, this sensitivity to quenching of the 110 aluminum alloy product may indicate that the 110 aluminum alloy product may have less than desirable properties, such as reduced stress corrosion cracking resistance or reduced strength values.

FIGS. 2A-2D provide corrosion profiles for an aluminum alloy product heat-treated according to the methods and techniques described herein. The heat-treated aluminum alloy product provided herein may be quench-insensitive aluminum alloy products. In FIGS. 2A-2D, the heat-treated aluminum alloy product is identified as a 210 aluminum alloy product. The 210 aluminum alloy product may be or comprise a 7xxx series aluminum alloy as described herein. Such alloys may exhibit improved quench-insensitivity and unexpectedly high strength values after quenching, such as high rupture and yield strengths, which can be maintained when subjected to a corrosion test. The properties of the aluminum alloy products described herein can be achieved due to their compositions and the methods by which they are produced and processed. Advantageously, the final properties of the aluminum alloy products can be achieved while subjected to a one-step aging treatment. Additionally, aluminum alloy products can be relatively quench-insensitive, meaning that they can be cooled at slower cooling rates without resulting in undesirable changes in properties, allowing for additional processing time between the heat treatment process and the quenching process, reduced quenching costs, and/or reduced distortion. An aluminum alloy as described herein may optionally have an elemental composition as provided in Table 1 (not according to the invention).

Table 1.

An aluminum alloy as described herein may have an elemental composition as given in Table 2 (not according to the invention).

Table 2.

An aluminum alloy as described herein may have an elemental composition as given in Table 3 (not according to the invention).

Table 3.

An aluminum alloy as described herein may have an elemental composition as given in Table 4 (not according to the invention).

Table 4

As examples, the alloys described herein include zinc (Zn) in an amount of 4.00% to 15.00% (e.g., 5.40% to 9.50%, 5.60% to 9.30%, 5.80% to 9.20%, or 4.00% to 5.00%) based on the total weight of the alloy. For example, the alloy may include 4.00%, 4.10%, 4.20%, 4.30%, 4.40%, 4.50%, 4.60%, 4.70%, 4.80%, 4.90%, 5.00%, 5.10%, 5.20%, 5.30%, 5.40%, 5.50%, 5.60%, 5.70%, 5.80%, 5.90%, 6.00%, 6.10%, 6.20%, 6.30%, 6.40%, 6.50%, 6.60%, 6.70%, 6.80%, 6.90%, 7.00%, 7.10%, 7.20%, 7.30%, 7.40%, 7.50%, 7.60%, 7.70%, 7.80%, 7.90%, 8.00%, 8.10%, 8.20%, 8.30%, 8.40%, 8.50%, 8.60%, 8.70%, 8.80%, 8.90%, 9.00%, 9.10%, 9.20%, 9.30%, 9.40%, 9.50%, 9.60%, 9.70%, 9.80%, 9.90%, 10.00%, 10.10%, 10.20%, 10.30%, 10.40%, 10.50%, 10.60%, 10.70%, 10.80%, 10.90%, 11.00%, 11.10%, 11.20%, 11.30%, 11.40%, 11.50%, 11.60%, 11.70%, 11.80%, 11.90%, 12.00%, 12.10%, 12.20%, 12.30%, 12.40%, 12.50%, 12.60%, 12.70%, 12.80%, 12.90%, 13.00%, 13.10%, 13.20%, 13.30%, 13.40%, 13.50%, 13.60%, 13.70%, 13.80%, 13.90%, 14.00%, 14.10%, 14.20%, 14.30%, 14.40%, 14.50%, 14.60%, 14.70%, 14.80%, 14.90% or 15.00% Zn. Optionally, the alloy may include from 4.00% to 4.10%, from 4.10% to 4.20%, from 4.20% to 4.30%, from 4.30% to 4.40%, from 4.40% to 4.50%, from 4.50% to 4.60%, from 4.60% to 4.70%, from 4.70% to 4.80%, from 4.80% to 4.90%, from 4.90% to 5.00%, from 5.00% to 5.10%, from 5.10% to 5.20%, from 5.20% to 5.30%, from 5.30% to 5.40%, from 5.40% to 5.50%, from 5.50% to 5.60%, from 5.60% to 5.70%, from 5.70% to 5.80%, from 5.80% to 5.90%, from 5.90% to 6.00%, from 6.00% to 6.10%, from 6.10% to 6.20%, from 6.20% to 6.30%, from 6.30% to 6.40%, from 6.40% to 6.50%, from 6.50% to 6.60%, from 6.60% to 6.70%, from 6.70% to 6.80%, from 6.80% to 6.90%, from 6.90% to 7.00%, from 7.00% to 7.10%, from 7.10% to 7.20%, from 7.20% to 7.30%, from 7.30% to 7.40%, from 7.40% to 7.50%, from 7.50% to 7.60%, from 7.60% to 7.70%, from 7.70% to 7.80%, from 7.80% to 7.90%, from 7.90% to 8.00%, from 8.00% to 8.10%, from 8.10% to 8.20%, from 8.20% to 8.30%, from 8.30% to 8.40%, from 8.40% to 8.50%, from 8.50% to 8.60%, from 8.60% to 8.70%, from 8.70% to 8.80%, from 8.80% to 8.90%, from 8.90% to 9.00%, from 9.00% to 9.10%, from 9.10% to 9.20%, from 9.20% to 9.30%, from 9.30% to 9.40%, from 9.40% to 9.50%, from 9.50% to 9.60%, from 9.60% to 9.70%, from 9.70% to 9.80%, from 9.80% to 9.90%, from 9.90% to 10.00%, from 10.00% to 10.10%, from 10.10% to 10.20%, from 10.20% to 10.30%, from 10.30% to 10.40%, 10.40% to 10.50%, 10.50% to 10.60%, 10.60% to 10.70%, 10.70% to 10.80%, 10.80% to 10.90%, 10.90% to 11.00%, 11.00% to 11.10%, 11.10% to 11.20%, 11.20% to 11.30%, 11.30% to 11.40%, 11.40% to 11.50%, 11.50% to 11.60%, 11.60% to 11.70%, 11.70% to 11.80%, from 11.80% to 11.90%, from 11.90% to 12.00%, from 12.00% to 12.10%, from 12.10% to 12.20%, from 12.20% to

14.80%, 14.80% to 14.90%, or 14.90% to 15.00% Zn. All expressed as a percentage by weight.

The alloys described include copper (Cu) in an amount of 0.30% to 2.50% or 0.20% to 2.10% based on the total weight of the alloy. For example, the alloy may include 0.20%, 0.21%, 0.22%, 0.23%, 0.24%, 0.25%, 0.26%, 0.27%, 0.28%, 0.29%, 0.30%, 0.35%, 0.4%, 0.45%, 0.50%, 0.55%, 0.60%, 0.65%, 0.70%, 0.75%, 0.80%, 0.85%, 0.90%, 0.95%, 1.0%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2.0%, 2.1%, 2.2%, 2.3%, 2.4%, or 2.5% Cu. Optionally, the alloy may include 0.20% to 0.21%, 0.21% to 0.22%, 0.22% to 0.23%, 0.23% to 0.24%, 0.24% to 0.25%, 0.25% to 0.26%, 0.26% to 0.27%, 0.27% to 0.28%, 0.28% to 0.29%, 0.29% to 0.30%, 0.30% to 0.35%, 0.35% to 0.40%, 0.40% to 0.45%, 0.45% to 0.50%, 0.50% to 0.55%, 0.55% to 0.60%, 0.60% to 0.65%, 0.65% to 0.70%, 0.70% to 0.75%, 0.75% to 0.80%, 0.80% to 0.85%, 0.85% to 0.90%, 0.90% to 0.95%, 0.95% to 1.0%, 1.0% to 1.1%, 1.1% to 1.2%, 1.2% to 1.3%, 1.3% to 1.4%, or 1.4% to 1.5% Cu. All are expressed as % by weight.

The alloys described herein include magnesium (Mg) in an amount of 1.60% to 2.60% or 2.20% to 2.40%. In some instances, the alloy may include 1.60%, 1.70%, 1.80%, 1.90%, 2.00%, 2.10%, 2.20%, 2.30%, 2.40%, 2.50%, or 2.60% Mg. Optionally, the alloy may include 1.60% to 1.70%, 1.80% to 1.80%, 1.80% to 1.90%, 1.90% to 2.00%, 2.00% to 2.10%, 2.10% to 2.20%, 2.20% to 2.30%, 2.30% to 2.40%, 2.40% to 2.50%, or 2.50% to 2.60% Mg. All are expressed in % by weight.

Optionally, the combined content of Zn, Cu and Mg may range from 5.00% to 14.00% (e.g., from 5.50% to 13.50%, from 6.00% to 13.00%, from 6.50% to 12.50% or from 7.00% to 12.00%). For example, the combined content of Zn, Cu and Mg may be 5.00%, 5.50%, 6.00%, 6.50%, 7.00%, 7.50%, 8.00%, 8.50%, 9.00%, 9.50%, 10.00%, 10.50%, 11.00%, 11.50%, 12.00%, 12.50%, 13.00%, 13.50% or 14.00%. Optionally, the combined content of Zn, Cu and Mg may be from 5.00% to 5.50%, from 5.50% to 6.00%, from 6.00% to 6.50%, from 6.50% to 7.00%, from 7.00% to 7.50%, from 7.50% to 8.00%, from 8.00% to 8.50%, from 8.50% to 9.00%, from 9.00% to 9.50%, from 9.50% to 10.00%, from 10.00% to 10.50%, from 10.50% to 11.00%, from 11.00% to 11.50%, from 11.50% to 12.00%, from 12.00% to 13.00%, from 13.00% to 14.00%, from 14.00% to 15.00%, from 15.00% to 16.00%, from 16.00% to 17.00%, from 17.00% to 18.00%, from 18.00% to 19.00%, from 19.00% to 20.00%, from 20.00% to 21.00%, from 21.00% to 22.00%, from 22.00% to 23.00%, from 23.00% to 24.00%, from 24.00% to 25.00%, from 25.00% to 26.00%, from 26.00% to 27.00%, from 27.00% to 28.00%, from 28 12.00% to 12.50%, 12.50% to 13.00%, 13.00% to 13.50%, or 13.50% to 14.00%. All expressed as a percentage by weight.

The alloys described herein include iron (Fe) in an amount of 0.10% to 0.25% or 0.18% to 0.23% based on the total weight of the alloy. For example, the alloy may include 0.10%, 0.11%, 0.12%, 0.13%, 0.14%, 0.15%, 0.16%, 0.17%, 0.18%, 0.19%, 0.20%, 0.21%, 0.22%, 0.23%, 0.24%, or 0.25% Fe. Optionally, the alloy may include 0.10% to 0.11%, 0.11% to 0.12%, 0.12% to 0.13%, 0.13% to 0.14%, 0.14% to 0.15%, 0.15% to 0.16%, 0.16% to 0.17%, 0.17% to 0.18%, 0.18% to 0.19%, 0.19% to 0.20%, 0.20% to 0.21%, 0.21% to 0.22%, 0.22% to 0.23%, 0.23% to 0.24%, or 0.24% to 0.25%. All are expressed as % by weight.

The alloys described herein include silicon (Si) in an amount of 0.07% to 0.15% or 0.09% to 0.12% based on the total weight of the alloy. For example, the alloy may include 0.07%, 0.08%, 0.09%, 0.10%, 0.11%, 0.12%, 0.13%, 0.14%, or 0.15% Si. Optionally, the alloy may include 0.07% to 0.08%, 0.08% to 0.09%, 0.09% to 0.10%, 0.10% to 0.11%, 0.11% to 0.12%, 0.12% to 0.13%, 0.13% to 0.14%, or 0.14% to 0.15% Si. All are expressed in % by weight.

The alloys described herein include zirconium (Zr) in an amount of 0.09% to 0.15% or 0.05% to 0.15% based on the total weight of the alloy. For example, the alloy may include 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.10%, 0.11%, 0.12%, 0.13%, 0.14%, or 0.15% Zr. Optionally, the alloy may include 0.05% to 0.06%, 0.06% to 0.07%, 0.07% to 0.08%, 0.08% to 0.09%, 0.09% to 0.10%, 0.10% to 0.11%, 0.11% to 0.12%, 0.12% to 0.13%, 0.13% to 0.14%, or 0.14% to 0.15% Zr. All are expressed in % by weight.

The alloys described herein include manganese (Mn) in an amount of 0.02% to 0.05% or 0.04% to 0.09% based on the total weight of the alloy. For example, the alloy may include 0.02%, 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, or 0.09% Mn. Optionally, the alloy may include 0.02% to 0.03%, 0.03% to 0.04%, 0.04% to 0.05%, 0.05% to 0.06%, 0.06% to 0.07%, 0.07% to 0.08%, or 0.08% to 0.09% Mn. All are expressed in % by weight.

The alloys described herein include chromium (Cr) in an amount of 0.03% to 0.05% or 0.03% to 0.09% based on the total weight of the alloy. For example, the alloy may include 0.03%, 0.04%, 0.05%, 0.06%, 0.07%, 0.08%, or 0.09% Cr. Optionally, the alloy may include 0.03% to 0.04%, 0.04% to 0.05%, 0.05% to 0.06%, 0.06% to 0.07%, 0.07% to 0.08%, or 0.08% to 0.09% Cr. All are expressed in % by weight.

The alloys described herein include titanium (Ti) in an amount of 0.003% to 0.035% or 0.01% to 0.02% based on the total weight of the alloy. For example, the alloy may include 0.003%, 0.004%, 0.005%, 0.006%, 0.007%, 0.008%, 0.009%, 0.010%, 0.011% 0.012%, 0.013%, 0.014%, 0.015%, 0.016%, 0.017%, 0.018%, 0.019%, 0.020%, 0.021%, 0.022%, 0.023%, 0.024%, 0.025%, 0.026%, 0.027%, 0.028%, 0.029%, 0.03%, 0.031%, 0.032%, 0.033%, 0.034%, or 0.035% Ti. Optionally, the alloy may include 0.01% to 0.02%, or 0.02% to 0.03% Ti. All are expressed as % by weight.

The alloys described herein may include one more of Mo, Nb, Be, B, Co, Sn, Sr, V, In, Hf, Ag, and Ni in an amount up to 0.20% (e.g., 0.01% to 0.20% or 0.05% to 0.15%) based on the total weight of the alloy. For example, the alloy may include 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.10%, 0.11%, 0.12%, 0.13%, 0.14%, 0.15%, 0.16%, 0.17%, 0.18%, 0.19%, or 0.20% of one more of Mo, Nb, Be, B, Co, Sn, Sr, V, In, Hf, Ag, and Ni. Optionally, the alloy may include 0.01% to 0.02%, 0.02% to 0.03%, 0.03% to 0.04%, 0.04% to 0.05%, 0.05% to 0.06%, 0.06% to 0.07%, 0.07% to 0.08%, 0.08% to 0.09%, 0.09% to 0.10%, 0.10% to 0.11%, 0.11% to 0.12%, 0.12% to 0.13%, 0.13% to 0.14%, 0.14% to 0.15%, 0.15% to 0.16%, 0.16% to 0.17%, 0.17% to 0.18%, 0.18% to 0.19%, or 0.19% to 0.20% of one or more of Mo, Nb, Be, B, Co, Sn, Sr, V, In, Hf, Ag, and Ni. All expressed as % by weight.

Optionally, the alloy compositions described herein may further include other minor elements, sometimes referred to as impurities, for example, in amounts of 0.05% or less, 0.04% or less, 0.03% or less, 0.02% or less, or 0.01% or less. Such impurities may include, but are not limited to, Ga, Ca, Bi, Na, Pb, or combinations thereof. Accordingly, Ga, Ca, Bi, Na, or Pb may be present in the alloys in amounts of 0.05% or less, 0.04% or less, 0.03% or less, 0.02% or less, or 0.01% or less. The sum of all impurities does not exceed 0.15% (e.g., 0.10%). All are expressed as % by weight. The remaining or remaining percentage of any alloy is aluminum.

The aluminum alloy product 210 of FIGS. 2A-2D may include a novel aluminum alloy, such as that provided herein. The composition and manufacturing method of the aluminum alloy product 210 may provide quench insensitivity and improved strength values as compared to the aluminum alloy product 110 described in FIGS. 1A-1D. FIGS. 2A-2D may exhibit one aspect of the quench insensitivity of the aluminum alloy product 210. Similar to FIGS. 1A-1D, the aluminum alloy product 210 may be quenched at various quenching rates, subjected to a corrosion test, and a corrosion profile provided for each of the different quenching rates to illustrate the quench sensitivity. Beginning in FIG. 2A, the aluminum alloy product 210 corresponds to quenching at a rate of 550°C/s. A cooling rate of 550 °C/s can be achieved through water quenching. When cooled at a rapid cooling rate of 550 °C/s and subjected to a corrosion test, the aluminum alloy product 210 may exhibit pitting corrosion 220, identified by material loss cavities. Similarly, in FIGS. 2B and 2C , pitting corrosion 220 may also be exhibited when the aluminum alloy product 210 is subjected to a 350 °C/s cooling rate and corrosion test and a 250 °C/s cooling rate and corrosion test. In embodiments, a change in corrosion morphology from pitting corrosion 220 to intergranular corrosion 230 may occur at the lower cooling rates. For example, as set forth in FIG. 2D, intergranular corrosion 230 may be exhibited when the aluminum 210 alloy product is cooled at 5 °C/s and subjected to a corrosion test. In some cases, the aluminum 210 alloy product may exhibit intergranular corrosion 230 after the corrosion test when the cooling rate is 50 °C/s or less. However, in other cases, little or no intergranular corrosion 230 may be exhibited by the aluminum alloy 210 product after corrosion testing when the cooling rate is greater than or about 5 °C/s, such as from 5 °C/s to 25 °C/s, from 25 °C/s to 50 °C/s, from 50 °C/s to 75 °C/s, from 75 °C/s to 100 °C/s, from 100 °C/s to 125 °C/s, from 125 °C/s to 150 °C/s, from 150 °C/s to 175 °C/s, from 175 °C/s to 200 °C/s, from 200 °C/s to 225 °C/s, or from 225 °C/s to 250 °C/s. Low cooling rates, such as cooling rates as low as 200 °C/s, as low as 100 °C/s, as low as 50 °C/s, or as low as 25 °C/s, can be achieved by air cooling. Air cooling can include blast cooling the aluminum 210 alloy product or maintaining the aluminum 210 alloy product at ambient temperature. Additional details regarding cooling are described below.

FIGS. 3A-3D also provide corrosion profiles for a heat-treated aluminum alloy product according to this disclosure at various cooling rates. The heat-treated aluminum alloy products may be a quench-sensitive aluminum alloy product and are identified in FIGS. 3A-3D as aluminum alloy product 310. Aluminum alloy product 310 may include a novel aluminum alloy such as that provided herein. Thus, aluminum alloy product 310 may exhibit improved quench insensitivity and corresponding improved strength values, particularly as compared to aluminum alloy product 110 described in FIGS. 1A-1D. Aluminum alloy 310 may be quenched according to the quenching methods described herein. Similar to FIGS. described above, aluminum alloy 310 may be quenched at a rapid quench rate of 550°C/s. As described in FIG. 3A , the aluminum alloy product 310 may exhibit pitting corrosion 320 when cooled at this rapid cooling rate and subjected to a corrosion test. Pitting corrosion 320 may also be exhibited at lower cooling rates. As shown in FIGS. 3B and 3C , the aluminum alloy product 310 may exhibit pitting corrosion 320 after the corrosion test when cooled at the cooling rates of 350°C/s and 250°C/s. The corrosion morphology may change to intergranular corrosion 130 when the cooling rate is lower than 250°C/s, such as at 5°C/s, as illustrated in FIG. 3D . Accordingly, FIGs. 2A-2D and 3A-3D may illustrate one aspect of the quench insensitivity exhibited by the novel aluminum alloys provided herein, specifically showing that the corrosion morphology exhibited after quench testing does not change to intergranular corrosion 130 until cooling rates are lower than 250 °C/s.

Although FIGS. 1A through 3D may illustrate the type of corrosion formed when a quenched aluminum alloy product undergoes a corrosion test, FIG. 4 quantifies the degree to which each type of corrosion is exhibited within the product after testing. FIG. 4 provides an illustrative graph showing a comparison of corrosion depths by corrosion regions at different cooling rates for a quench-sensitive aluminum alloy product versus the heat-treated aluminum alloy product produced according to this disclosure. FIG. 4 provides three separate graphs placed side-by-side to facilitate comparison of the different aluminum alloy products. FIG. 4 includes graphs 405, 410, and 415, each of which provides data for a different aluminum alloy product quenched at various rates. Each of the aluminum alloy products depicted in FIG. 4 may be subjected to the same processing before being subjected to corrosion testing in accordance with ASTM G110, ASTM G129, and/or ASTM G139. Those standards are provided for aluminum corrosion testing that provide repeatable measurements of corrosion sensitivity for a particular material. Following ASTM G110, each of the aluminum alloy products used for FIG. 4 may be immersed in a sodium chloride and hydrogen peroxide solution. Each of the aluminum alloy products may be immersed for 24 hours and/or 48 hours. The data for each of the aluminum alloy products was collected and used to generate Charts 405, 410, and 415.

In graph 405, the depth of corrosion exhibited at various cooling rates is provided for a quench-sensitive aluminum alloy product. Graph 405 may correspond to aluminum alloy product 110 and represents an AA7075 aluminum alloy product. As discussed above with respect to FIGS. 1A-1D, aluminum alloy product 110 may be quench-sensitive and exhibit a change in corrosion morphology from pitting corrosion to intergranular corrosion at higher cooling rates. Graph 405 illustrates similar results, showing that pitting corrosion 420 is exhibited at faster cooling rates, such as 550°C/s and 350°C/s. However, once the cooling rate is reduced to 250 °C/s, the corrosion morphology can change to 430 intergranular corrosion. As highlighted by the box in Figure 405, Labeled “IGC Region,” the 110 aluminum alloy product can exhibit 430 intergranular corrosion when cooled at any rate at or below 250 °C/s. In some cases, intergranular corrosion may be observed in AA7075 aluminum alloy products subjected to corrosion testing processed using cooling rates of about 5 °C/s to about 250 °C/s or about 5 °C/s to about 350 °C/s, such as 5 °C/s to 250 °C/s, 5 °C/s to 260 °C/s, 5 °C/s to 270 °C/s, 5 °C/s to 280 °C/s, 5 °C/s to 290 °C/s, 5 °C/s to 300 °C/s, 5 °C/s to 310 °C/s, 5 °C/s to 320 °C/s, 5 °C/s to 330 °C/s, 5 °C/s to 340 °C/s. °C/s or from 5 °C/s to 345 °C/s.

Chart 405 also indicates the corrosion depth. Corrosion depth may refer to the degree to which the bulk of the aluminum alloy on a surface of the aluminum alloy product exhibits corrosion. In other words, corrosion depth may refer to a depth of the bulk of the aluminum alloy product at which corrosion may be present after the corrosion test. Chart 405 may include or represent data from multiple cooling tests for each cooling rate or from multiple locations on the samples subjected to the corrosion test. Thus, the blocks may correspond to an average of the observed corrosion depth, and the standard deviation or error bar may indicate the entire range of corrosion depth observed during the test. As illustrated in Chart 405, as cooling rates decrease, corrosion depth may increase. It may be desirable to limit corrosion, and thus a lower corrosion depth may also be desirable. As illustrated in Figure 405, at a cooling rate of 550 °C/s, 420 corrosion may extend to an average depth of approximately 50 pm into the aluminum alloy product and may correspond to pitting corrosion, for example. As the cooling rate decreases to 350 °C/s, 420 corrosion may extend further into the aluminum alloy product to an average depth of approximately 75 pm and may again correspond to pitting corrosion. As the corrosion morphology changes to intergranular corrosion, the corrosion depth may continue to increase. While the corrosion depth of 430 corrosion may decrease slightly as the aluminum alloy product cools at a rate of 150 °C/s, this point includes large error bars where the maximum corrosion depth is very large. The average corrosion depth for 430 corrosion at cooling rates of 5 °C/s to 250 °C/s may still be greater than the corrosion depth at faster cooling rates, such as 550 °C/s. An event at a low cooling rate of 5 °C/s can extend corrosion to a corrosion depth of approximately 85 pm.

Graphs 410 and 415 will illustrate the depths of corrosion observed for additional aluminum alloy products according to the present disclosure. The aluminum alloy products for which data are shown in Graphs 410 and 415 may be heat-treated aluminum alloy products. The heat-treated aluminum alloy product may be a quench-sensitive aluminum alloy product such as aluminum alloy products 210 and 310. The observed heat-treated aluminum alloy product may be an aluminum alloy product produced according to the methods and compositions described herein. For example, those aluminum alloy products may be produced from an aluminum alloy having the following elemental composition as provided in Table 5.

Table 5.

As illustrated in Figure 410, when the 4A aluminum alloy product is cooled and subjected to a corrosion test, 420 corrosion can be observed at most cooling rates. For example, pitting corrosion can be exhibited even at low cooling rates of 50°C/s or less. In the data obtained, when cooling rates decrease to 5°C/s, the 4A aluminum alloy product exhibits 430 intergranular corrosion (IGC). Furthermore, the corrosion exhibited by the 4A aluminum alloy product for which data are shown in Figure 410, regardless of the corrosion type, generally has a reduced total corrosion depth when compared to the quench-sensitive aluminum alloy product in Figure 405. Even at the lowest cooling rate of 5°C/s, a shallower corrosion depth is observed. While corrosion depth may increase somewhat as cooling rates decrease, the rate of increase in corrosion depth with increasing cooling rates may be minimal. For example, the corrosion depth of corrosion 420 shown in Figure 410 at a cooling rate of 550 °C/s may be approximately 40 pm, while the corrosion depth at a cooling rate of 5 °C/s is only slightly greater, at approximately 50 pm. In summary, the corrosion depth shown in Figure 410 is relatively constant when compared to the quench-sensitive aluminum alloy product of Figure 405. Additionally, as indicated by the standard deviation bars, the corrosion depth may also be relatively constant across multiple runs of the same test. The absence of deviation between different trials of the same test (i.e., multiple quenches at the same quenching rate) may additionally show the insensitivity of the aluminum alloy product to quenching indicating that changes in operating conditions may have minimal effect on corrosion sensitivity.

Chart 415 may indicate similar insensitivity to cooling for another aluminum alloy 4B product as described herein. Similar to the aluminum alloy 4A product for which data is shown in Chart 410, the corrosion morphology for the aluminum alloy product represented by Chart 415 may not change from pitting corrosion to intergranular corrosion until a cooling rate at or less than 5 °C/s. Unexpectedly, corrosion depths may decrease in some cases as cooling rates decrease. This result is unexpected when comparing the trends in corrosion depth versus cooling rates in Charts 405 and 410 which indicate an increase in corrosion depth with decreasing cooling rates. In graph 415, rates of 50 °C/s to 250 °C/s may represent that pitting corrosion is the primary corrosion 420 extending to corrosion depths of about 25 µm or less. As graphs 410 and 415 illustrate, when cooling rates of 5 °C/s to 550 °C/s are used, the corrosion depth after the corrosion test may be 0 µm to 300 µm, 5 µm to 300 µm, 0 µm to 200 µm, 5 µm to 100 µm, or 10 µm to 80 µm. For example, when the cooling rate is 125 °C/s the corrosion depth may be 5 µm to 150 µm or 25 µm to 50 µm.

As discussed above, quench sensitivity can impact the properties of an aluminum alloy product, specifically strength values. Exemplary strength characteristics may include yield strength, stress at break, grain elongation, and strain ratio. FIGS. 5-8 provide illustrative graphs depicting data comparisons between a quench-sensitive aluminum alloy product and heat-treated aluminum alloy products produced according to methods and techniques such as those provided herein. The quench-sensitive aluminum alloy product is represented by the data labeled “C” (black circle) in the graphs in FIGS. 5-8. In some embodiments, aluminum alloy product C may include a 7xxx series aluminum alloy product produced according to conventional methods and techniques. For example, aluminum alloy product C may correspond to an AA7075 aluminum alloy product (similar to aluminum alloy product 110). The data labeled “5A” (red circle) and “5B” (blue triangle) in the graphs in FIGS. 5 through 8 represent heat-treated aluminum alloy products that are quench-insensitive aluminum alloy products. 5A and 5B aluminum alloy products can be produced from aluminum alloys having the following elemental compositions as provided in Table 6.

Table 6.

Each of the 5A, 5B, and C aluminum alloy products can be prepared before undergoing the same mechanical testing procedure. To prepare the 5A, 5B, and C aluminum alloy products, the aluminum alloy products can be solubilized at a first temperature of 480°C. The aluminum alloy products can be held or retained at the first temperature for 5 minutes before being quenched in water baths maintained at temperatures of 25°C, 55°C, 65°C, 75°C, and 85°C to achieve quenching rates of 550°C/s, 350°C/s, 250°C/s, 150°C/s, and 50°C/s, respectively. To achieve a quenching rate of 5°C/s, the aluminum alloy products can be water quenched. After quenching, the aluminum alloy products can be subjected to a one-step aging process. An exemplary aging process may include a T6 or T7 temper or precipitation hardening. For the graphs in FIGs. 5 through 8, the aluminum alloy products may be subjected to an aging process in which the products may be reheated to a temperature of 125°C for 25 hours. After undergoing this aging process, the aluminum alloy products may be subjected to mechanical testing, corrosion testing according to ASTM G110, stress corrosion cracking evaluation according to ASTM G129, and/or stress corrosion cracking evaluation according to ASTM G139. The following FIGs. 5-9, 10A-10C, and 11A-11C provide data collected from testing of the prepared 5A, 5B, and 5C aluminum alloy products performed according to the processes discussed above.

FIG. 5 provides graph 500 illustrating a comparison of the yields exhibited by aluminum alloy products 5A, 5B, and C. Yield, also known as creep, is a material property that defines the stress at which a material begins to plastically deform. Plastic deformation is the permanent deformation of a product subjected to stresses such as elongation, compression, buckling, bending, or torsion. Creep can be an important component when characterizing the strength of an aluminum alloy product.

As shown in Figure 500, 5A and 5B aluminum alloy products produced from quench-sensitive 7xxx series aluminum alloy compositions such as those provided above and produced according to techniques such as those provided herein may exhibit superior creep when compared to aluminum alloy product C. For example, the 5A and 5B aluminum alloy products may exhibit creeps of 400 MPa to 600 MPa. Specifically, the 5A and 5B aluminum alloy products may exhibit creeps of 500 MPa to 650 MPa at cooling rates of 50°C/s to 550°C/s. For example, the 5A and 5B aluminum alloy products may exhibit creep of 560 MPa to 580 MPa when the cooling rate is 125°C/s. In some embodiments, the quench-insensitive aluminum alloy products may exhibit creep of about 550 MPa to about 600 MPa at cooling rates of 50°C/s to 550°C/s or creep of about 525 MPa to about 600 MPa at cooling rates of 350°C/s to 550°C/s. For example, at a cooling rate of 550°C/s, aluminum alloy products 5A and 5B may exhibit creep of about 572 MPa and about 579 MPa, respectively. By comparison, aluminum alloy product C may exhibit creep of about 532 MPa at a cooling rate of 550°C/s. At cooling rates of 350°C/s and 50°C/s, aluminum alloy product 5A may exhibit fluences of approximately 572 MPa and 553 MPa, respectively, and aluminum alloy product 5B may exhibit fluences of approximately 575 MPa and 569 MPa, respectively. In comparison, aluminum alloy product C may exhibit fluences of approximately 524 MPa and 509 MPa at cooling rates of 350°C/s and 50°C/s, respectively.

The creep improvement of aluminum alloy products 5A and 5B may be even more evident at low cooling rates, such as a cooling rate of 5 °C/s. At a cooling rate of 5 °C/s, aluminum alloy products 5A and 5B exhibit creeps of approximately 439 MPa and 489 MPa, which may be 100 MPa greater than the creep of aluminum alloy product C at a cooling rate of 5 °C/s. At 5 °C/s, aluminum alloy product C exhibits a creep of approximately 347 MPa. Advantageously, aluminum alloy products 5A and 5B exhibit a drop in creep of less than 25% when the cooling rate is decreased from 550 °C/s to 5 °C/s. In comparison, the C aluminum alloy product exhibits a drop of more than 25%, such as 35%, when the cooling rate drops from 550 °C/s to 5 °C/s.

FIG. 6 provides graph 600 illustrating a comparison of the ultimate tensile strength exhibited by aluminum alloy products 5A, 5B, and C. Ultimate tensile strength (UTS) may correspond to a material's ability to resist elongation loads. In contrast to a tensile test in which a force exerted on a material tends to reduce the size of the material, the ultimate tensile strength test tests the material's ability to resist elongation. Ultimate tensile strength may be measured by the maximum stress that a material can withstand while being stretched or pulled before breaking.

Similar to creep, aluminum alloy products 5A and 5B may exhibit higher ultimate tensile strength at various cooling rates when compared to aluminum alloy product C. As shown in Figure 600, aluminum alloy products 5A and 5B exhibit ultimate tensile strengths (also referred to herein as yield stresses) of 500 MPa to 650 MPa at cooling rates of 5°C/s to 550°C/s. For example, aluminum alloy products 5A and 5B may exhibit an ultimate tensile strength of 605 MPa to 615 MPa when the cooling rate is 125°C/s. In some embodiments, the quench-insensitive aluminum alloy products may exhibit yield stresses of 585 MPa to 625 MPa at cooling rates of 50°C/s to 550°C/s. For example, at a cooling rate of 550°C/s, aluminum alloy products A and B exhibit ultimate stresses of about 614 MPa and about 618 MPa, respectively. In comparison, aluminum alloy product C exhibits a ultimate stress of about 584 MPa at a cooling rate of 550°C/s. At cooling rates of 350°C/s and 50°C/s, aluminum alloy product 5A exhibits ultimate stresses of about 614 MPa and about 593 MPa, respectively, and aluminum alloy product 5B exhibits ultimate stresses of about 618 MPa and about 605 MPa, respectively. In comparison, aluminum alloy product C exhibits ultimate stresses of about 578 MPa and about 566 MPa at cooling rates of 350°C/s and 50°C/s, respectively.

Even at low cooling rates, such as 5 °C/s, aluminum alloy products 5A and 5B exhibit higher yield stresses compared to aluminum alloy product C. For example, at a cooling rate of 5 °C/s, the quench-insensitive aluminum alloy products can exhibit yield stresses of about 475 MPa to about 550 MPa. As illustrated in FIG. 6, the yield stresses at 5 °C/s for aluminum alloy products 5A and 5B are about 507 MPa and about 544 MPa, respectively. In comparison, aluminum alloy product C exhibits a yield stress of about 458 MPa when cooled at a rate of 5 °C/s.

Turning now to FIG. 7, the total elongation (TE) of aluminum alloy products 5A, 5B, and C when subjected to tension is illustrated. Total elongation, expressed as a percentage change over a fixed gauge, may correspond to the percentage to which a material can be stretched before it breaks. In some embodiments, total elongation may be a proxy for the formability of the aluminum alloy products.

As illustrated in Figure 700, aluminum alloy products 5A and 5B may exhibit a total elongation of 10.00% to 15.00% for cooling rates of 5°C/s to 550°C/s. For example, at faster cooling rates, such as 550°C/s, aluminum alloy products 5A and 5B may exhibit a total elongation of about 14.70% and about 14.31%, respectively. When the cooling rate decreases to 350°C/s, 50°C/s, and 5°C/s, aluminum alloy product 5A exhibits a total elongation of about 15.10%, about 13.29%, and about 10.46%, respectively. Similarly, aluminum alloy product 5B exhibits a total elongation of 14.48%, 13.65%, and 10.15% when the cooling rate is lowered to 350 °C/s, 50 °C/s, and 5 °C/s, respectively. When the cooling rate is 125 °C/s, aluminum alloy products 5A and 5B may exhibit a total elongation of 13.80% to 14.20%. In some cases, quench-insensitive aluminum alloy products may exhibit a uniform elongation of 7.50% to 10.50%. For example, aluminum alloy products 5A and 5B may exhibit a uniform elongation of 9.00% to 9.60% when the cooling rate is 125 °C/s.

As illustrated in FIG. 7, aluminum alloy product C may exhibit a total elongation of 14.09% to 15.25% for cooling rates of 5°C/s to 550°C/s. For example, aluminum alloy product C may exhibit a total elongation of greater than 15.00% at a cooling rate of 550°C/s. When the cooling rate decreases to 350°C/s, 50°C/s, and 5°C/s, aluminum alloy product C may exhibit a total elongation of about 14.60%, about 14.31%, and about 14.09%, respectively. Uniform elongation may correspond to the elongation of a material at a maximum load until necking occurs. In some cases, uniform elongation may represent the ductility or formability of a material under uniaxial deformation.

FIG. 8 provides graph 800 illustrating a comparison of strain ratios exhibited by aluminum alloy products 5A, 5B, and C. Strain ratios can be a useful measure of susceptibility to stress corrosion cracking. For example, the lower the strain ratio, the greater the susceptibility to stress corrosion cracking for an aluminum alloy product. As illustrated by graph 800, the strain ratios exhibited by aluminum alloy products 5A and 5B can be consistently greater than the strain ratios exhibited by aluminum alloy product C. Even at low cooling rates, such as 5 °C/s, where intergranular corrosion may be observed, the strain ratios exhibited by aluminum alloy products 5A and 5B can be greater than the strain ratios exhibited by aluminum alloy product C.

In embodiments, the quench-insensitive aluminum alloy products may exhibit a strain ratio of 0.3 to 1.0 for cooling rates of 5 °C/s to 550 °C/s. In other embodiments, the strain ratio may be 0.5 to 1.0 when the quench-insensitive aluminum alloy products are cooled at rates of 250 °C/s to 500 °C/s. When the cooling rate is 125 °C/s, the aluminum alloy products 5A and 5B may exhibit a strain ratio of 0.375 to 0.425. For example, when the aluminum alloy products 5A and 5B are cooled at a rapid rate of 550 °C/s, the strain ratio may be 0.5 to 1.0. As illustrated in Figure 800, for all cooling rates tested, aluminum alloy products 5A and 5B may exhibit a strain ratio greater than 0.3. In comparison, the strain ratio exhibited by aluminum alloy product C may be less than 0.3 across the cooling rates tested. This may indicate that aluminum alloy product C is more susceptible to stress corrosion cracking than aluminum alloy products 5A and 5B.

FIG. 9 provides graph 900, illustrating a comparison of precipitate-free zones exhibited by aluminum alloy products 5A, 5B, and C. During an aging process, precipitation may be exhibited when solutes and other hardening compounds precipitate from the aluminum alloy solution. Zones or cavities in which little or no precipitation is exhibited may be referred to as precipitate-free zones. Precipitation-free zones may be exhibited because precipitates, like solutes, nucleate heterogeneously over vacancies. A grain boundary may be a sink for vacancies, such that regions adjacent to the boundaries are unable to nucleate precipitate, even though the alloy solution may be supersaturated with solute. Precipitation-free zones may be undesirable because they may act as regions of weakness. For example, precipitate-free zones may be more susceptible to corrosive attack than other points within the aluminum alloy. Consequently, reducing the number and width of non-precipitate zones may be desirable to improve the strength and corrosion sensitivity of an aluminum alloy product.

As illustrated in Figure 900, the width of the precipitate-free zones formed during an aging process can increase as cooling rates decrease. Aluminum alloy C product can develop larger precipitate-free zones during cooling when compared to aluminum alloy 5A and 5B products. For example, at rapid cooling rates,

At 550 °C/s, aluminum alloy product C may exhibit precipitate-free zones having an average width of approximately 45 nm. In comparison, at a cooling rate of 550 °C/s, aluminum alloy products 5A and 5B may exhibit precipitate-free zones having an average width of

of approximately 35 nm and 32 nm, respectively. Even at low cooling rates, the aluminum alloy C product may have larger precipitate-free zones than the aluminum alloy 5A and 5B products. For example, at 5 °C/s, the aluminum alloy C product may exhibit precipitate-free zones having an average width of approximately 200 nm, while the aluminum alloy 5B products

Aluminum 5A and 5B may exhibit precipitate-free zones having an average width of approximately

90 nm and 150 nm, respectively.

FIGS. 10A-10C and 11A-11C depict images corresponding to 5A aluminum alloy products.

and C illustrated in graph 900 of FIG. 9. For example, the images provided in FIGs. 10A, 10B and

10C can be taken using scanning transmission electron microscopy (STEM) methods

that describe areas without precipitation 1010 that may correspond to one or more data points on the graph

900. That is, the widths or measurements of the precipitate-free zones 1010 provided in FIGS. 10A-11C may be used in graph 900.

FIGS. 10A-10C correspond to aluminum alloy product C. FIG. 10A depicts precipitate-free zones 1010 exhibited after aluminum alloy product C is cooled at a rate of

550 °C/s. FIGS. 10B and 10C depict precipitate-free zones 1010 exhibited after the aluminum alloy product C is cooled at rates of 150 °C/s and 5 °C/s. As shown, the precipitate-free zones

1010 may increase in size (e.g., width) as the cooling rate decreases. FIGS. 11A, 11B, and 11C may provide similar images taken using the methods

STEM experiments describing 1010 precipitate-free zones exhibited by the 5A aluminum alloy product.

FIG. 11A depicts precipitate-free zones 1010 exhibited after the 5A aluminum alloy product

cooled at 550 °C/s. Similarly, FIGS. 11B and 11C depict precipitate-free zones 1110 exhibited after the aluminum alloy product 5A is cooled at 150 °C/s and 5 °C/s, respectively. While

that the precipitate-free zones 1110 of the 5A aluminum alloy product may become larger as

As the cooling rate decreases, the width of the precipitate-free zones may become smaller than the

of the precipitate-free zones 1010 exhibited by the aluminum alloy C product cooled at the same rate. This is also described by the data provided in graph 900 of FIG. 9. For example,

As illustrated in Figure 900, when the 5A aluminum alloy product is cooled from 0.5 °C/s to 125 °C/s, then the widths of the precipitate-free zone can fluctuate from 10 nm to 110 nm. Specifically, when the 5A aluminum alloy product is cooled at 125 °C/s, then the 5A aluminum alloy product

may exhibit precipitate-free zone widths of 10 nm to 13 nm.

It should be noted that while the aforementioned improved corrosion resistance and mechanical properties refer to discrete cooling rates, this is not intended to be limiting. Similar properties can be exhibited for a range of quenching rates. The improved resistance to

The corrosion and mechanical properties described with reference to FIGS. 1 to 9 can be exhibited for the aluminum alloy products provided herein when the quenching rate is 0.5

°C/s to 125 °C/s. For example, the cooling rate can fluctuate from 5 °C/s to 125 °C/s, 10 °C/s to

125 °C/s, 15 °C/s to 125 °C/s, 20 °C/s to 125 °C/s, 25 °C/s to 125 °C/s, 30 °C/s to 125 °C/s, 35 °C/s to 125 °C/s, 40 °C/s to 125 °C/s, °C/s at 125 °C/s, 50 °C/s at 125 °C/s, 55 °C/s at 125 °C/s, 60 °C/s at 125 °C/s, 65 °C/s at

100 °C/s to 125 °C/s, 105 °C/s to 125 °C/s, 110 °C/s to 125 °C/s, 115 °C/s to 125 °C/s, 120 °C/s

at 125 °C/s, 5 °C/s at 120 °C/s, 10 °C/s at 120 °C/s, 15 °C/s at 120 °C/s, 20 °C/s at 120 °C/s, 25 °C/s at 120 °C/s,

30°C/s to 120°C/s, 35°C/s to 120°C/s, 40°C/s to 120°C/s, 45°C/s to 120°C/s, 50°C/s to 120°C/s, 55°C/s to

120 °C/s, 60 °C/s to 120 °C/s, 65 °C/s to 120 °C/s, 70 °C/s to 120 °C/s, 75 °C/s to 120 °C/s, 80 °C/s to 120 °C/s, 85 °C/s to 120 °C/s, 90 °C/s at 120 °C/s, 95 °C/s at 120 °C/s, 100 °C/s at 120 °C/s, 105 °C/s at 120 °C/s, 110 °C/s at

120 °C/s, 115 °C/s to 120 °C/s, 5 °C/s to 115 °C/s, 10 °C/s to 115 °C/s, 15 °C/s to 115 °C/s, 20 °C/s to 115 °C/s,

25°C/s to 115°C/s, 30°C/s to 115°C/s, 35°C/s to 115°C/s, 40°C/s to 115°C/s, 45°C/s to 115°C/s, 50°C/s to

115 °C/s, 55 °C/s to 115 °C/s, 60 °C/s to 115 °C/s, 65 °C/s to 115 °C/s, 70 °C/s to 115 °C/s, 75 °C/s to 115 °C/s, 80 °C/s to 115 °C/s, 85 °C/s at 115 °C/s, 90 °C/s at 115 °C/s, 95 °C/s at 115 °C/s, 100 °C/s at 115 °C/s, 105 °C/s at

115 °C/s, 110 °C/s to 115 °C/s, 5 °C/s to 110 °C/s, 10 °C/s to 110 °C/s, 15 °C/s to 110 °C/s, 20 °C/s to 110 °C/s,

25°C/s to 110°C/s, 30°C/s to 110°C/s, 35°C/s to 110°C/s, 40°C/s to 110°C/s, 45°C/s to 110°C/s, 50°C/s to

85 °C/s at 110 °C/s, 90 °C/s at 110 °C/s, 95 °C/s at 110 °C/s, 100 °C/s at 110 °C/s, 105 °C/s at

110 °C/s, 5 °C/s to 105 °C/s, 10 °C/s to 105 °C/s, 15 °C/s to 105 °C/s, 20 °C/s to 105 °C/s, 25 °C/s to 105 °C/s,

30°C/s to 105°C/s, 35°C/s to 105°C/s, 40°C/s to 105°C/s, 45°C/s to 105°C/s, 50°C/s to 105°C/s, 55°C/s to

90 °C/s at 105 °C/s, 95 °C/s at 105 °C/s, 100 °C/s at 105 °C/s, 5 °C/s at 100 °C/s, 10 °C/s at

45 °C/s at 100 °C/s, 50 °C/s at 100 °C/s, 55 °C/s at 100 °C/s, 60 °C/s at 100 °C/s, 65 °C/s at

100°C/s, 70°C/s to 100°C/s, 75°C/s to 100°C/s, 80°C/s to 100°C/s, 85°C/s to 100°C/s, 90°C/s to 100°C/s, 95°C/s to 100°C/s, 5°C/s at 105 °C/s, 10 °C/s at 105 °C/s, 15 °C/s at 105 °C/s, 20 °C/s at 105 °C/s, 25 °C/s at 105 °C/s, 30 °C/s at 105 °C/s, 35 °C/s at 105 °C/s, 40 °C/s at 105 °C/s, 45 °C/s to 105 °C/s, 50 °C/s to 105 °C/s, 55 °C/s to 105 °C/s, 60 °C/s to 105 °C/s, 65 °C/s to 105 °C/s, 70 °C/s to 105 °C/s, 75 °C/s to 105 °C/s, 80 °C/s to 105 °C/s, 85 °C/s to 105 °C/s, 90 °C/s to 105 °C/s, 95 °C/s to 105 °C/s, 100 °C/s to 105 5 °C/s to 95 °C/s,

FIG. 12 provides an overview of a method 1200 for manufacturing a quench-sensitive aluminum alloy product. In block 1205, an aluminum alloy product undergoes one or more rolling or forming processes. One or more of the rolling or forming processes may include a hot rolling process in block 1207, a cold rolling process in block 1209, or both. Optionally, the heat-treated aluminum alloy product may be cold-rolled to a final gauge thickness. The final gauge thickness may be from 0.2 mm to 10.0 mm (e.g., 2.0 mm). For example, the heat treated aluminum alloy product may be cold rolled to a final gauge thickness of 0.2 mm, 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1.0 mm, 1.1 mm, 1.2 mm, 1.3 mm, 1.4 mm, 1.5 mm, 1.6 mm, 1.7 mm, 1.8 mm, 1.9 mm, 2.0 mm, 2.1 mm, 2.2 mm, 2.3 mm, 2.4 mm, 2.5 mm, 2.6 mm, 2.7 mm, 2.8 mm, 2.9 mm, 3.0 mm, 3.1 mm, 3.2 mm, 3.3 mm, 3.4 mm, 3.5 mm, 3.6 mm, 3.7 mm, 3.8mm, 3.9mm, 4.0mm, 4.1mm, 4.2mm, 4.3mm, 4.4mm, 4.5mm, 4.6mm, 4.7mm, 4.8mm, 4.9mm, 5.0mm, 5.1mm, 5.2mm, 5.3mm, 5.4mm, 5.5mm, 5.6mm, 5.7mm, 5.8mm, 5.9mm, 6.0mm, 6.1mm, 6.2mm, 6.3mm, 6.4mm, 6.5mm, 6.6mm, 6.7mm, 6.8mm, 6.9mm, 7.0mm, 7.1mm, 7.2mm, 7.3mm, 7.4mm, 7.5mm, 7.6 mm, 7.7mm, 7.8mm, 7.9 mm, 8.0 mm, 8.1 mm, 8.2 mm, 8.3 mm, 8.4 mm, 8.5 mm, 8.6 mm, 8.7 mm, 8.8 mm, 8.9 mm, 9.0 mm, 9.1 mm, 9.2 mm, 9.3 mm, 9.4 mm, 9.5 mm, 9.6 mm, 9.7 mm, 9.8 mm, 9.9 mm or 10.0 mm. Cold rolling may be performed to result in the heat treated aluminum alloy product having a final gauge thickness representing a reduction from the overall gauge of 20%, 50%, 75% or 85%.

In block 1210, the rolled aluminum alloy product is heated. The rolled aluminum alloy product may be a quench-insensitive aluminum alloy product. In embodiments, the rolled aluminum alloy product may include an aluminum alloy having an elemental composition according to those provided in Tables 5 and 6. The rolled aluminum alloy product includes a 7xxx series aluminum alloy as defined in the claims. In some embodiments, the rolled aluminum alloy product may be a slab, strip, plate, sheet, or foil. Optionally, ingots and/or billets may be used with method 1200.

The rolled aluminum alloy product is heated to a first temperature in block 1210. The rolled aluminum alloy product may be heated during a heat treatment process. In some embodiments, the heat treatment process may be a solution heat treatment process. During heating, the rolled aluminum alloy product is heated to a first temperature of at least 400°C to 525°C (e.g., at least 425°C, at least 450°C, at least 460°C, or at least 465°C). In some instances, the first temperature may range from 400°C to 525°C, 425°C to 510°C, 450°C to 510°C, 450°C to 500°C, 450°C to 480°C, or 450°C to 475°C. In some embodiments, the first temperature may be a dissolution temperature.

During heating the rolled aluminum alloy product, the heating rate to the first temperature can be 70 °C/hour or less, 60 °C/hour or less, or 50 °C/hour or less.

In embodiments, the heat treatment process may be or include a hot rolling process. The hot rolling process may include a reversible hot rolling operation and/or a tandem or serial hot rolling operation. The hot rolling process may be carried out at a temperature ranging from about 250°C to about 550°C (e.g., from about 300°C to about 500°C or from about 350°C to about 450°C). In the hot rolling process, the rolled aluminum alloy product may be hot rolled to a thickness gauge of 12 mm or less (e.g., a gauge of 3 mm to 8 mm thickness). For example, the rolled aluminum alloy product may be hot rolled to an 11 mm gauge thickness or less, a 10 mm gauge thickness or less, a 9 mm gauge thickness or less, an 8 mm gauge thickness or less, a 7 mm gauge thickness or less, a 6 mm gauge thickness or less, a 5 mm gauge thickness or less, a 4 mm gauge thickness or less, or a 3 mm gauge thickness or less. In some embodiments, the hot rolling process may occur at a different point during method 1200. For example, the hot rolling process may occur after a forming step or after a cooling step.

The rolled aluminum alloy product may be held at the first temperature, or within 10°C of the first temperature, for a time from 30 seconds to 30 minutes in block 1220. In some instances, the time duration is from 15 seconds to 30 minutes, 15 seconds to 5 minutes, 15 seconds to 30 seconds, 30 seconds to 6 hours, 30 seconds to 3 hours, 30 seconds to 1 hour, 30 seconds to 30 minutes, 30 seconds to 5 minutes, 30 seconds to 1 minute, 1 minute to 30 minutes, 5 minutes to 30 minutes. Optionally, the rolled aluminum alloy product may be held within 5°C of the first temperature, or within 1°C of the first temperature for the specified time.

At the end of the heat treatment process, the rolled aluminum alloy product may optionally undergo one or more forming processes at block 1230. For example, at block 1230, the rolled aluminum alloy product may undergo a hot forming process. In some embodiments, the rolled aluminum alloy product may be hot formed after heating but before the rolled aluminum alloy product is cooled. The rolled aluminum alloy product as provided herein may have good ductility or formability at elevated temperatures. This may allow the rolled aluminum alloy product to be malleable and achieve improved formability. Hot forming the rolled aluminum alloy product when the product is at or near the first temperature may allow the rolled aluminum alloy product to be formed into a variety of complex shapes. For example, after heating the rolled aluminum alloy product, the product may be transferred to a press or die where it is formed into a desired shape. The rolled aluminum alloy (and optionally formed) product is cooled in block 1240. In block 1240, the rolled aluminum alloy product may be cooled to a second temperature of between about 10° C. and about 100° C. in a quenching process to generate a heat-treated aluminum alloy product. The second temperature may be ambient or room temperature in some embodiments. The quenching process may be performed using a slow quench practice. The cooling rate in the slow quench practice ranges from about 0.5° C. per second to about 125° C. per second. In some cases, the cooling rate may range from about 5° C. per second to about 125° C. per second.

In some embodiments, cooling the rolled aluminum alloy product in block 1240 may include two or more cooling processes. The rolled aluminum alloy product may be subjected to a first cooling to an intermediate temperature and then a second cooling until the rolled aluminum alloy product reaches the second temperature. For example, the rolled aluminum alloy product may be cooled from the first temperature to an intermediate temperature through a hot forming process. The intermediate temperature may be higher than the second temperature. Thus, a second cooling may be required to cool the rolled aluminum alloy product to the second temperature. The second cooling rate may be greater than the first cooling rate.

The heat-treated aluminum alloy product generated by the quenching process may exhibit superior mechanical properties over conventional aluminum alloy products. Specifically, the heat-treated aluminum alloy product as described herein exhibits a strain ratio of 0.3 to 0.8. The strain ratio is determined according to a standard ASTM G129 test method. Other exemplary mechanical properties exhibited by the heat-treated aluminum alloy product may include an ultimate tensile strength of 500 MPa to 650 MPa, a yield strength of 400 MPa to 600 MPa, a uniform elongation of 7.50% to 10.50%, and a total elongation of 10.00% to 15.00%. The heat-treated aluminum alloy generated in block 1240 may be the 210, 310 aluminum alloy products, or the 4A and 4B aluminum alloy products discussed with reference to FIG. 4 or aluminum alloy products 5A and 5B discussed with reference to FIGS. 5-11C. In some cases, the heat-treated aluminum alloy product may be a hot-formed aluminum alloy product when the rolled aluminum alloy product is subjected to a hot-forming process. In other cases, the heat-treated aluminum alloy product may be an aluminum alloy product formed when the rolled aluminum alloy product is subjected to one or more forming processes.

At block 1242, cooling the rolled aluminum alloy product may include subjecting the rolled aluminum alloy product to a water quenching process. The water quenching process may include cold water immersion, hot water immersion, boiling water, or water spray. In various embodiments, cooling the rolled aluminum alloy product at block 1240 may include other cooling methods. For example, block 1240 may include a forced air quenching process. The forced air quenching process may include air blast or still air processes. Other cooling methods that may be utilized at block 1240 may include polyalkylene glycol solutions, liquid nitrogen, quench oils, or salt solutions.

Optionally, blocks 1230 and 1240 may be combined. For example, in some cases, the rolled aluminum alloy product may be cooled through a die quenching process. During a hot forming process, the rolled aluminum alloy product may be formed into parts using cold dies. Because cold dies are cooler than the hot-rolled aluminum alloy product, the cold dies can provide rapid cooling to the rolled aluminum alloy product. In some cases, the hot forming process may be considered part of the quenching process. In other cases, the rolled aluminum alloy product may undergo the hot forming process before or after the quenching process. In additional cases, the hot forming process may occur between a first quenching process and a second quenching process.

After the rolled aluminum alloy product is cooled in block 1240, the heat-treated aluminum alloy product may undergo an aging process in block 1250. For example, the heat-treated aluminum alloy product may undergo a hardening process such as a T6 or T7 temper. In some embodiments, the aging process in block 1250 may include reheating the heat-treated aluminum alloy product to a temperature of about 100°C to about 170°C, holding the heat-treated aluminum alloy product at a temperature of about 100°C to about 150°C for a period of time, and cooling the sheet to a temperature near or at ambient temperature. In other instances, the aging process may include reheating the heat-treated aluminum alloy product to a temperature of about 100°C to about 150°C; maintaining the heat-treated aluminum alloy product at a temperature of about 100° C. to about 150° C. for a period of time; heating the heat-treated aluminum alloy product to a temperature greater than about 150° C.; maintaining the heat-treated aluminum alloy product at a temperature greater than about 150° C. (e.g., about 150° C. to about 170° C.) for a period of time; and cooling the heat-treated aluminum alloy product to room temperature. The heat-treated aluminum alloy product may be maintained at the temperature for a period of time greater than 10 minutes, 20 minutes, 30 minutes, 40 minutes, 50 minutes, 60 minutes, 70 minutes, 80 minutes, 90 minutes, 100 minutes, 110 minutes, 2 hours, 6 hours, 12 hours, 18 hours, 24 hours, 30 hours, 32 hours, or 48 hours. For example, heat-treated aluminum alloy product may undergo an aging process in which the product is reheated to a temperature of 100°C to 170°C and held at that temperature for 12 hours to 30 hours.

In some cases, the heat-treated aluminum alloy product may be subjected to a heat treatment for baking paint, for example, heating the heat-treated aluminum alloy product to a temperature greater than about 150°C (e.g., 160°C, 170°C, 180°C, 190°C, 200°C or greater) and holding the heat-treated aluminum alloy product at the temperature greater than about 140°C (e.g., between about 150°C, 160°C, 170°C, 180°C, 190°C, 200°C or greater) for a period of time (e.g., 10 minutes, 20 minutes, 30 minutes, 40 minutes, 50 minutes, 60 minutes, 70 minutes, 80 minutes, 90 minutes, 100 minutes, 110 minutes or 120 minutes).

Turning now to FIG. 13, graph 1300 illustrates a temperature profile of an aluminum alloy product as a function of time according to embodiments of the present disclosure. Graph 1300 may describe or correspond to an embodiment of a quench-responsive aluminum alloy product manufacturing method. For example, graph 1300 may correspond to a method of manufacturing a 210, 310, 4A, 4B, 5A, 5B aluminum alloy product, or any aluminum alloy product having a composition according to Tables 1-6. Beginning at step 1310, the rolled aluminum alloy product may be heated from room temperature to a first temperature of 480°C during a heat treatment process. The heating may take approximately 50 seconds, as illustrated. In embodiments, the room temperature may correspond to ambient conditions, such as approximately 40°C. In this embodiment, the heat treatment process may be a solution heat treatment process, indicated by the notation SHT. In step 1320, the rolled aluminum alloy product may be held at the first temperature for a period of time, such as about 5 minutes. After this period of time, the rolled aluminum alloy product may be cooled in step 1330 to generate a heat-treated aluminum alloy product. In step 1330, multiple cooling rates are illustrated. For example, a cooling rate of 550°C/s, 350°C/s, 150°C/s, 50°C/s, or 5°C/s may be used in step 1330. The cooling in step 1330 may employ any of the various cooling methods discussed herein. In some embodiments, the rolled aluminum alloy product may be cooled to a second temperature, such as room temperature. Optionally, the heat-treated aluminum alloy product can be kept at room temperature for 24 hours.

In some cases, the heat-treated aluminum alloy product may be subjected to an aging process. In step 1350, the heat-treated aluminum alloy product may be subjected to a T6 tempering process. Optionally, a T7 tempering process may be used. As shown in figure 1300, in step 1350 the heat-treated aluminum alloy product may be reheated to a temperature of 125°C. The heat-treated aluminum alloy product may be held at 125°C for 24 hours before returning to room temperature.

Methods of Using Aluminum Alloy Products Described

The aluminum alloy products described herein may be used in automotive and other transportation applications, including aircraft and rail applications. For example, the aluminum alloy products described herein may be used to prepare automotive structural parts, such as bumpers, side beams, roof beams, cross beams, pillar reinforcement (e.g., A-pillars, B-pillars, and C-pillars), interior panels, exterior panels, side panels, inner canopies, outer canopies, rocker panels, or decklid panels. The aluminum alloy products and methods described herein may also be used in aircraft or rail vehicle applications, to prepare, for example, outer and inner panels. The aluminum alloy products described herein may be incorporated within an upper wing, a lower wing, or other fuselage assemblies for aerospace applications.

The aluminum alloy products and methods described herein may also be used in electronic or other desired applications. For example, the aluminum alloy products and methods described herein may be used to prepare housings for electronic devices, including mobile phones and tablet computers. In some examples, the aluminum alloy products may be used to prepare housings for external cases of mobile phones (e.g., smartphones), lower chassis of tablets, and other portable electronic devices.

The foregoing description of the embodiments, including the illustrated embodiments, has been presented solely for illustrative and descriptive purposes and is not intended to be exhaustive or limiting of the precise forms disclosed. Numerous modifications, adaptations, and uses thereof will be apparent to those skilled in the art.

Claims (5)

1. A method comprising: heating a rolled aluminum alloy product to a first temperature of 400°C to 525°C, wherein the rolled aluminum alloy product comprises a 7xxx series aluminum alloy comprising: from 4.00% by weight to 15.00% by weight of Zn, from 0.30% by weight to 2.50% by weight of Cu, from 1.60% by weight to 2.60% by weight of Mg, from 0.10% by weight to 0.25% by weight of Fe, from 0.07% by weight to 0.15% by weight of Si, from 0.09% by weight to 0.15% by weight of Zr, from 0.02% by weight to 0.05% by weight of Mn, from 0.03% by weight to 0.05% by weight of Cr, from 0.003% by weight to 0.035% by weight of Ti, and remainder Al, with a maximum of 0.15% by weight for the sum of all impurities, and wherein the rolled aluminium alloy product further comprises up to 0.20% by weight of one or more of Mo, Nb, Be, B, Co, Sn, Sr, V, In, Hf, Ag, Sc and Ni; or from 4.00% by weight to 15.00% by weight of Zn, from 0.20% by weight to 2.10% by weight of Cu, from 2.20% by weight to 2.40% by weight of Mg, from 0.18% by weight to 0.23% by weight of Fe, from 0.09% by weight to 0.12% by weight of Si, from 0.05% by weight to 0.15% by weight of Zr, from 0.04% by weight to 0.09% by weight of Mn, from 0.03% by weight to 0.09% by weight of Cr, from 0.01% by weight to 0.02% by weight of Ti, up to 0.15% by weight of impurities, remainder Al, and wherein the rolled aluminum alloy product further comprises up to 0.20% by weight of one or more of Mo, Nb, Be, B, Co, Sn, Sr, V, In, Hf, Ag, Sc and Ni; Maintain the rolled aluminum alloy product at the first temperature or within 10°C of the first temperature for a time between 15 seconds and 30 minutes; and cooling the rolled aluminum alloy product at a cooling rate of 0.5 ° C/s to 125 ° C/s, thereby generating a heat-treated aluminum alloy product, wherein the rolled aluminum alloy product is cooled until the rolled aluminum alloy product reaches a second temperature of 10 ° C to 100 ° C, and wherein the heat-treated aluminum alloy product has a strain ratio of 0.3 to 0.8, and wherein the strain ratio is determined in accordance with a standard ASTM G129 test method. 2. The method of claim 1, wherein the cooling comprises a first cooling at a first cooling rate to an intermediate temperature, a second cooling at a second cooling rate to the second temperature, wherein the second cooling rate is greater than the first cooling rate; and/or where the cooling rate is from 5 °C/s to 125 °C/s; and/or where the cooling rate is 10 °C/s to 125 °C/s. 3. The method of claim 1 or 2, wherein the first temperature is a dissolution temperature; and/or wherein the second temperature is a room temperature; and/or wherein heating and cooling the rolled aluminum alloy product corresponds to a solution heat treatment process; and/or further comprising subjecting the rolled aluminum alloy product to a hot forming process after heating the rolled aluminum alloy product. 4. The method of any one of claims 1-3, wherein cooling the rolled aluminum alloy product comprises a die cooling process; and/or wherein the cooling of the rolled aluminum alloy product comprises a water quenching process; and/or wherein the cooling of the rolled aluminum alloy product comprises a forced air cooling process. 5. The method of any of claims 1-4, further comprising aging the heat-treated aluminum alloy product to a T6 temper; and/or which further comprises aging the heat-treated aluminum alloy product to a T7 temper; and/or further comprising heating the heat-treated aluminum alloy product to a temperature of 100°C to 170°C and holding it at said temperature for 12 hours to 30 hours.