High strength extruded alloy

Abstract

The disclosure provides an aging process or method for aging an aluminum alloy. For example, an aging process may be performed on a 6xxx Al-Si-Mg-Cu aluminum alloy to result in the production of such alloys with improved intergranular corrosion (IGC) resistance. The disclosed aging process includes subjecting the solution heat treated and quenched 6xxx aluminum alloy to a temperature above the age hardening temperature of the alloy but below the solution heat treatment temperature for a short period of time, and then subjecting the alloy to an aging heat treatment at the age hardening temperature.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to U.S. Non-Provisional Application No. 18 / 139,465, filed on April 26, 2023, and U.S. Provisional Application No. 63 / 334,765, filed on April 26, 2022, which are incorporated herein by reference in their entirety. Technical Field

[0003] The disclosure relates to alloys, more particularly to aluminum alloys, and more particularly to aluminum extrusion alloys. Background Art

[0004] Aluminum alloys are widely used in various industries due to their favorable properties, including low density, high strength to weight ratio and good corrosion resistance. Some aluminum extrusion alloys are used in the automotive industry because aluminum extrusion alloys can achieve very complex shapes and profiles. A kind of such alloy is the 6xxx series. The 6xxx series aluminum alloys (which include aluminum-magnesium-silicon (Al-Mg-Si) alloy system) are popular because of their excellent combination of strength, formability and weldability. The 6xxx alloy series can be used for automotive body structures, suspensions and transmission system components. Aluminum extrusion alloys (such as 6xxx extrusion alloys) can achieve innovative lightweight designs with integrated functions. There is a general need for improved extrusion alloys. Summary of the invention

[0005] The following summary is a high-level overview of various aspects and introduces some of the concepts that are further described in the following detailed description section. The summary is not intended to be used in isolation to determine the scope of the claimed subject matter. The subject matter should be understood by reference to appropriate portions of the entire specification, any or all of the drawings, and each claim.

[0006] The disclosure provides an improved 6xxx series aluminum alloy with improvements in manufacturing methods and advantages over conventional alloys. The alloy composition includes aluminum (Al), magnesium (Mg), silicon (Si) and one or more additional elements, such as copper (Cu), zinc (Zn) and / or manganese (Mn).

[0007] In some aspects, the technology described herein relates to a method comprising: subjecting an alloy to a first temperature for a first duration, wherein the first temperature is greater than an age hardening temperature of the alloy and less than a solution heat treatment temperature; and subjecting the alloy to a second temperature for a second duration.

[0008] In some aspects, the technology described herein relates to a method further comprising: prior to subjecting the alloy to the first temperature, subjecting the alloy to a solution heat treatment at a solution heat treatment temperature.

[0009] In some aspects, the technology described herein relates to a method wherein the second temperature is an age hardening temperature.

[0010] In some aspects, the technology described herein relates to a method wherein the alloy includes a solution heat treated and quenched alloy.

[0011] In some aspects, the technology described herein relates to a method wherein the alloy includes a 6xxx aluminum alloy.

[0012] In some aspects, the technology described herein relates to a method wherein the alloy includes a 6xxx Al-Si-Mg-Cu aluminum alloy.

[0013] In some aspects, the technology described herein relates to the above method, further comprising: obtaining a resulting alloy, wherein the resulting alloy has improved intergranular corrosion (IGC) resistance.

[0014] In some aspects, the technology described herein relates to a method wherein the first temperature is 200°C to 210°C.

[0015] In some aspects, the technology described herein relates to a method wherein the first duration is between 5 minutes and 20 minutes.

[0016] In some aspects, the technology described herein relates to a method wherein the second temperature is between 150°C and 200°C.

[0017] In some aspects, the technology described herein relates to a method wherein the second duration is between 30 minutes and 3 hours.

[0018] In some aspects, the technology described herein relates to a method comprising: subjecting an aluminum alloy to a first temperature for a first duration; and subjecting the aluminum alloy to a second temperature for a second duration, wherein the first temperature is higher than the second temperature, wherein the first duration is 5 minutes to 20 minutes. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Reference is made to the accompanying drawings, which form a part of the disclosure and illustrate embodiments in which the systems and methods described in this specification may be practiced. Throughout, like reference numerals designate the same or similar components.

[0020] Figure 1 is an exemplary flow chart according to an embodiment of the method disclosed herein.

[0021] Figure 2 is a schematic comparison diagram showing an exemplary treatment process according to an embodiment of the method disclosed herein and a conventional aging process. DETAILED DESCRIPTION

[0022] Improving 6xxx series aluminum alloys is extremely challenging. Embodiments disclosed herein provide improvements in various properties and / or manufacturing processes.

[0023] The disclosure provides an improved 6xxx series aluminum alloy with improvements in manufacturing methods and advantages over conventional alloys. The alloy composition includes aluminum (Al), magnesium (Mg), silicon (Si) and one or more additional elements, such as copper (Cu), zinc (Zn) and / or manganese (Mn).

[0024] Alloys (such as aluminum alloys, particularly 6xxx series aluminum alloys) can be subjected to solution heat treatment. Solution heat treatment is performed in order to obtain a high practical solid solution concentration of a hardening solute (e.g., Cu, Mg, Si, or Zn). The solubility of these elements increases significantly with temperature, especially just below the eutectic melting temperature. Therefore, the most favorable temperature for solution treatment is close to the eutectic temperature (e.g., about 5°C to 8°C lower than the eutectic temperature).

[0025] Figure 1 A flow chart of an embodiment of a method 100 disclosed herein is shown. The method 100 includes subjecting an alloy (e.g., an aluminum alloy, a 6xxx aluminum alloy, etc.) to a solution heat treatment 102 at a specific solution heat treatment temperature. The alloy is then subjected to a two-step artificial aging process, which includes a first temperature treatment 104 at a first duration and a second temperature treatment 106 at a second duration. In the first temperature treatment 104, a first temperature is applied. The first temperature of the first temperature treatment 104 is greater than the age hardening temperature of the alloy and less than the solution heat treatment temperature used in the solution heat treatment 102. During the aging treatment 106, the second temperature may be the age hardening temperature.

[0026] According to some embodiments, the solution heat treatment 102 includes a quenching process, or is followed by a quenching process. According to some embodiments, the quenching is performed after the solution heat treatment 102. According to some embodiments, the quenching is not performed after the solution heat treatment 102.

[0027] According to some embodiments, the aging process does not include a natural aging process. According to some embodiments, the aging process includes a natural aging process. According to some embodiments, the natural aging process is after the first temperature treatment. According to some embodiments, the natural aging process is before the second temperature treatment. According to some embodiments, the natural aging process is after the first temperature treatment but before the second temperature treatment. According to some embodiments, the natural aging process is 1 hour to 24 hours. According to some embodiments, the aging process does not include any other conventional artificial aging process.

[0028] In some aspects, embodiments of the methods described herein may combine any of the following first temperature, first duration, second temperature, and / or second duration. Thus, in some embodiments, the first temperature is 205°C. Thus, in some embodiments, the first temperature is 200°C to 205°C. Thus, in some embodiments, the first temperature is 205°C to 210°C. Thus, in some embodiments, the first temperature is 200°C to 202°C; 200°C to 204°C; 200°C to 206°C; 200°C to 208°C; or 200°C to 210°C. Thus, in some embodiments, the first temperature is 202°C to 204°C; 202°C to 206°C; 202°C to 208°C; or 202°C to 210°C. Thus, in some embodiments, the first temperature is 204°C to 206°C; 204°C to 208°C; or 204°C to 210°C. Thus, in some embodiments, the first temperature is 206°C to 208°C; or 206°C to 210°C. Thus, in some embodiments, the first temperature is 208°C to 210°C. Thus, in some embodiments, the first duration is 5 minutes to 15 minutes. Thus, in some embodiments, the first duration is 15 minutes to 20 minutes. Thus, in some embodiments, the first duration is 5 minutes to 8 minutes; 5 minutes to 10 minutes; 5 minutes to 12 minutes; 5 minutes to 14 minutes; 5 minutes to 16 minutes; 5 minutes to 18 minutes; or 5 minutes to 20 minutes. Thus, in some embodiments, the first duration is 8 minutes to 10 minutes; 8 minutes to 12 minutes; 8 minutes to 14 minutes; 8 minutes to 16 minutes; 8 minutes to 18 minutes; or 8 minutes to 20 minutes. Thus, in some embodiments, the first duration is 10 minutes to 12 minutes; 10 minutes to 14 minutes; 10 minutes to 16 minutes; 10 minutes to 18 minutes; or 10 minutes to 20 minutes. Thus, in some embodiments, the first duration is from 12 minutes to 14 minutes; 12 minutes to 16 minutes; 12 minutes to 18 minutes; or 12 minutes to 20 minutes. Thus, in some embodiments, the first duration is from 14 minutes to 16 minutes; 14 minutes to 18 minutes; or 14 minutes to 20 minutes. Thus, in some embodiments, the first duration is from 16 minutes to 18 minutes; or 16 minutes to 20 minutes. Thus, in some embodiments, the first duration is from 18 minutes to 20 minutes. Thus, in some embodiments, the second temperature is 175°C. Thus, in some embodiments, the second temperature is from 150°C to 175°C. Thus, in some embodiments, the second temperature is from 175°C to 200°C. Thus, in some embodiments, the second temperature is from 150°C to 160°C; 150°C to 170°C; 150°C to 180°C; or 150°C to 200°C.Thus, in some embodiments, the second temperature is 150°C to 160°C; 150°C to 170°C; 150°C to 180°C; or 150°C to 200°C. Thus, in some embodiments, the second temperature is 160°C to 170°C; 160°C to 180°C; or 160°C to 200°C. Thus, in some embodiments, the second temperature is 170°C to 180°C; or 170°C to 200°C. Thus, in some embodiments, the second temperature is 180°C to 200°C. Thus, in some embodiments, the second duration is 1 hour. Thus, in some embodiments, the second duration is 2 hours. Thus, in some embodiments, the second duration is 3 hours. Thus, in some embodiments, the second duration is 30 minutes to 2 hours. Thus, in some embodiments, the second duration is 2 hours to 3 hours. Thus, in some embodiments, the second duration is 30 minutes to 40 minutes; 30 minutes to 50 minutes; 30 minutes to 60 minutes; 30 minutes to 70 minutes; 30 minutes to 80 minutes; 30 minutes to 90 minutes; 30 minutes to 100 minutes; 30 minutes to 110 minutes; 30 minutes to 120 minutes; 30 minutes to 130 minutes; 30 minutes to 140 minutes; 30 minutes to 150 minutes; 30 minutes to 160 minutes; 30 minutes to 170 minutes; or 30 minutes to 180 minutes. Thus, in some embodiments, the second duration is 40 minutes to 50 minutes; 40 minutes to 60 minutes; 40 minutes to 70 minutes; 40 minutes to 80 minutes; 40 minutes to 90 minutes; 40 minutes to 100 minutes; 40 minutes to 110 minutes; 40 minutes to 120 minutes; 40 minutes to 130 minutes; 40 minutes to 140 minutes; 40 minutes to 150 minutes; 40 minutes to 160 minutes; 40 minutes to 170 minutes; or 40 minutes to 180 minutes. Thus, in some embodiments, the second duration is 50 minutes to 60 minutes; 50 minutes to 70 minutes; 50 minutes to 80 minutes; 50 minutes to 90 minutes; 50 minutes to 100 minutes; 50 minutes to 110 minutes; 50 minutes to 120 minutes; 50 minutes to 130 minutes; 50 minutes to 140 minutes; 50 minutes to 150 minutes; 50 minutes to 160 minutes; 50 minutes to 170 minutes; or 50 minutes to 180 minutes. Thus, in some embodiments, the second duration is 60 minutes to 70 minutes; 60 minutes to 80 minutes; 60 minutes to 90 minutes; 60 minutes to 100 minutes; 60 minutes to 110 minutes; 60 minutes to 120 minutes; 60 minutes to 130 minutes; 60 minutes to 140 minutes; 60 minutes to 150 minutes; 60 minutes to 160 minutes; 60 minutes to 170 minutes; or 60 minutes to 180 minutes.Thus, in some embodiments, the second duration is 70 minutes to 80 minutes; 70 minutes to 90 minutes; 70 minutes to 100 minutes; 70 minutes to 110 minutes; 70 minutes to 120 minutes; 70 minutes to 130 minutes; 70 minutes to 140 minutes; 70 minutes to 150 minutes; 70 minutes to 160 minutes; 70 minutes to 170 minutes; or 70 minutes to 180 minutes. Thus, in some embodiments, the second duration is 80 minutes to 90 minutes; 80 minutes to 100 minutes; 80 minutes to 110 minutes; 80 minutes to 120 minutes; 80 minutes to 130 minutes; 80 minutes to 140 minutes; 80 minutes to 150 minutes; 80 minutes to 160 minutes; 80 minutes to 170 minutes; or 80 minutes to 180 minutes. Thus, in some embodiments, the second duration is 90 minutes to 100 minutes; 90 minutes to 110 minutes; 90 minutes to 120 minutes; 90 minutes to 130 minutes; 90 minutes to 140 minutes; 90 minutes to 150 minutes; 90 minutes to 160 minutes; 90 minutes to 170 minutes; or 90 minutes to 180 minutes. Thus, in some embodiments, the second duration is 100 minutes to 110 minutes; 100 minutes to 120 minutes; 100 minutes to 130 minutes; 100 minutes to 140 minutes; 100 minutes to 150 minutes; 100 minutes to 160 minutes; 100 minutes to 170 minutes; or 100 minutes to 180 minutes. Thus, in some embodiments, the second duration is from 110 minutes to 120 minutes; 110 minutes to 130 minutes; 110 minutes to 140 minutes; 110 minutes to 150 minutes; 110 minutes to 160 minutes; 110 minutes to 170 minutes; or 110 minutes to 180 minutes. Thus, in some embodiments, the second duration is from 120 minutes to 130 minutes; 120 minutes to 140 minutes; 120 minutes to 150 minutes; 120 minutes to 160 minutes; 120 minutes to 170 minutes; or 120 minutes to 180 minutes. Thus, in some embodiments, the second duration is from 130 minutes to 140 minutes; 130 minutes to 150 minutes; 130 minutes to 160 minutes; 130 minutes to 170 minutes; or 130 minutes to 180 minutes. Thus, in some embodiments, the second duration is 140 minutes to 150 minutes; 140 minutes to 160 minutes; 140 minutes to 170 minutes; or 140 minutes to 180 minutes. Thus, in some embodiments, the second duration is 150 minutes to 160 minutes; 150 minutes to 170 minutes; or 150 minutes to 180 minutes.

[0029] Thus, in some embodiments, the second duration is from 160 minutes to 170 minutes; or from 160 minutes to 180 minutes. Thus, in some embodiments, the second duration is from 170 minutes to 180 minutes.

[0030] After the second temperature treatment 106, the method 100 includes obtaining a resulting alloy 108. Examples of resulting alloys may include, for example, 6xxx Al-Si-Mg-Cu aluminum alloys with improved intergranular corrosion (IGC) resistance, which may be produced using these embodiments of the method.

[0031] According to some embodiments, as used herein, improved IGC resistance means a maximum IGC depth of less than 250 μm, an average IGC depth of less than 150 μm, or both.

[0032] Therefore, some embodiments of the aging process include the following steps:

[0033] 1. subjecting the solution heat treated and quenched 6xxx aluminum alloy to a temperature above the age hardening temperature of the alloy but below the solution heat treatment temperature for a short period of time (e.g., 205° C. for 16 minutes), and

[0034] 2. The alloy is then subjected to an aging heat treatment at the age hardening temperature for a longer period of time (eg, 175°C for about 2 hours).

[0035] Advantages of the embodiments of the methods disclosed herein include significant cost savings and improved properties of the resulting alloys. For example, for A210 extruded alloys, embodiments of the methods can reduce the aging time from greater than 8 hours (conventional aging) to about 3 hours (embodiments of the method). Figure 2 The differences between method 100 and a conventional single-step aging process for a 6xxx A210 alloy are schematically illustrated. The dashed line represents a conventional single-step aging process, which includes ramping to 175°C in 45 minutes and then soaking at 175°C for 8 hours. The solid line represents an exemplary method 100 used for a 6xxx A210 alloy. In the example, method 100 includes ramping to 205°C in 45 minutes, soaking the alloy at 205°C for 16 minutes (at a first temperature for a first duration), cooling to 175°C in about 1 minute, and soaking the alloy at 175°C for 2 hours (at a second temperature for a second duration). For a conventional aging process, the total aging time is greater than 8.5 hours, and for method 100 applied in the example, the total aging time is only about 3 hours.

[0036] Obviously, this will significantly reduce the manufacturing time and cost of A210 extrusion products, and thus make A210 alloy more competitive with other extrusion alloys. The embodiment of the method can also significantly improve the IG corrosion performance of A210 extrusion alloy without sacrificing other properties, such as bendability or yield strength. Therefore, the embodiments disclosed herein provide an economical and effective solution to the IG corrosion problem and can accelerate the application of A210 alloy.

[0037] FIG3 summarizes some advantages of the disclosed embodiments over conventional aging processes. Embodiments of the method can be used for many 6xxx alloys. Exemplary results are provided below.

[0038] Example 1: A210 alloy

[0039] Alcoa 6xxx high strength extrusion alloy A210 is used to study the effect of the method disclosed herein. The A210 extrusion segment has a wall thickness varying from 2.5 mm to 4 mm. Extrusion is performed at an extrusion speed of about 10 m / min on a 2500 ton extruder. The outlet temperature is controlled at about 555°C to 565°C. The extruded profile is water quenched at a quenching rate of 50°C / sec to 75°C / sec. Table 1 lists the actual composition of the A210 alloy evaluated.

[0040] Table 1. Composition of Exemplary Alcoa High Strength 6xxx A210 Alloys

[0041]

[0042] The A210 alloy samples were treated via eight different aging processes. The eight processes are described in detail in Table 2. Process 1 is a conventional aging process commonly used for A210 alloys, where aging is performed at an aging temperature of 175°C for 8 hours. Processes 2 to 8 are artificial aging processes according to embodiments of the methods disclosed herein, where a first temperature treatment is performed for a first duration and then a second temperature treatment is performed for a second duration. The total combined time of the first duration and the second duration can be significantly shorter than the conventional duration (e.g., 8 hours).

[0043] Table 2

[0044]

[0045] The alloys derived from the above eight processes were evaluated. Performance evaluation includes IG corrosion and tensile properties. Three tensile specimens and two IG corrosion specimens were used for each condition. Tensile tests were performed at Westmoreland Mechanical Testing and Research Lab in accordance with ASTM E8 / E8M specifications. Intergranular corrosion tests were performed in accordance with ISO 11846 Method B. Measuring and checking the IG corrosion depth (which is not clearly described in ISO11846 Method B) was performed as follows. After the immersion test, the sample was examined under a stereoscope at 20X magnification. Two sections were marked for each sample to include the most severely attacked position. After mounting and polishing, the sections were observed under an optical microscope. Continuous pictures were taken on both sides of each section. About 18 pictures will cover the entire length (one side) of the section. The maximum corrosion depth on each picture was measured. A normal distribution diagram can be obtained, and then the maximum corrosion depth and the average corrosion depth are determined. These effects of the eight aging processes on the mechanical properties and IG corrosion depth of the A210 alloy are reported in Table 3.

[0046] Table 3. Mechanical properties and IG corrosion depth of A210 alloy

[0047]

[0048] The average tensile test results for the A210 alloy for each of the eight different aging processes are shown in Table 3. It is expected that the conventional aging process (Process 1) will produce a resulting alloy that meets the following target properties: having a tensile strength (UTS) greater than 380 MPa, a yield strength (YS) greater than 350 MPa, and an elongation (E) greater than 8%.

[0049] Surprisingly, Processes 2 to 8 can also produce alloys that meet the following target properties: having a tensile strength (UTS) greater than 380 MPa, a yield strength (YS) greater than 350 MPa, and an elongation (E) greater than 8%.

[0050] Table 3 also shows the maximum corrosion depth and average corrosion depth under each aging condition. These results show surprising results, in which all two-step aging processes with 205°C for 16 minutes as the first step aging show better IG corrosion performance than conventional aging processes. In particular, the samples aged using process 6 and process 8 can meet the maximum corrosion depth and average corrosion depth requirements. Specifically, the alloy produced by process 6 (the first temperature is 205°C for 16 minutes, and the second temperature is 175°C for 2 hours) is more commercially advantageous because its total aging cycle time is only 3 hours.

[0051] Example 2: A210 alloy with 3.5% pre-strain

[0052] Alcoa 6xxx high strength extrusion alloy A210 is used to study the effect of the method disclosed in this article. The A210 extrusion segment has a wall thickness varying from 2.5mm to 4mm. Extrusion is carried out at an extrusion speed of about 10 meters per minute on a 2500-ton extruder. The outlet temperature is controlled at about 555°C to 565°C. The extruded profile is water quenched at a quenching rate of 50°C / second to 75°C / second. Table 1 lists the actual composition of the A210 alloy evaluated. Before any aging process, 3.5% pre-strain is applied to all samples in the extrusion direction.

[0053] A210 alloy samples with 3.5% pre-strain were treated via four different aging processes. The four processes are described in detail in Table 4. Process 1 is a conventional aging process commonly used for A210 alloys, in which aging is performed at an aging temperature of 175°C for 8 hours. Processes 2 to 4 are aging processes according to an embodiment of the method disclosed herein, in which a first temperature treatment is performed for a first duration and then a second temperature treatment is performed for a second duration. In process 4, 24 hours of natural aging is included between the first temperature treatment and the second temperature treatment. For processes 2 to 3, the total combined time of the first duration and the second duration is significantly shorter than the conventional duration (e.g., 8 hours).

[0054] Table 4

[0055]

[0056] The alloys produced from the above four processes were evaluated. The performance evaluation included IG corrosion, tensile properties and 3-point bending test. The 3-point bending test was carried out according to VDA 238-100 specification. The 3-point bending test parameters are as follows. The test results are reported in Table 5.

[0057] Sample length: ~60mm

[0058] Sample width: ~25mm

[0059] Roller spacing: 6mm

[0060] Knife radius: 0.4mm

[0061] Roller diameter: 30mm

[0062] Prestressing speed: 10mm / min

[0063] Preload: 100N

[0064] Test speed: 20mm / min

[0065] Test end criteria: Maximum load – 4%

[0066] Table 5 shows some surprising results. Apparently, the embodiments of the methods in the disclosure (Processes 2 to 4) can significantly improve the IG corrosion performance of the resulting alloys without significant adverse effects on mechanical properties and bending angles. Processes 3 and 4 can significantly improve the IG corrosion performance of the resulting A210 alloy (with 3.5% pre-strain before aging) compared to the conventional aging process (Process 1). Although Process 2 can also improve IG corrosion performance, Process 2 does not show better results than Processes 3 and 4.

[0067] Table 5. Mechanical properties and IG corrosion depth of A210 alloy (with 3.5% pre-strain)

[0068]

[0069] In addition to those benefits and improvements already disclosed, other objects and advantages of the disclosure will become apparent from the following description in conjunction with the accompanying drawings. Detailed embodiments of the disclosure are disclosed herein; however, it should be understood that the disclosed embodiments are merely illustrative of the disclosure that can be implemented in various forms. In addition, each example given with respect to various embodiments of the disclosure is intended to be illustrative and not restrictive.

[0070] Various aspects are provided below. It should be understood that any feature stated in the following aspects may be combined with any other aspect.

[0071] Aspect 1. A method comprising:

[0072] subjecting the alloy to a first temperature for a first duration,

[0073] wherein the first temperature is greater than the age hardening temperature of the alloy and less than the solution heat treatment temperature; and

[0074] The alloy is subjected to a second temperature for a second duration.

[0075] Aspect 2. The method according to aspect 1, further comprising:

[0076] Prior to subjecting the alloy to the first temperature, the alloy is solution heat treated at a solution heat treatment temperature.

[0077] Aspect 3. The method according to any one of aspects 1 to 2, wherein the second temperature is an age hardening temperature.

[0078] Aspect 4. The method according to any one of aspects 1 to 3, wherein the alloy comprises an alloy that has been solution heat treated and quenched.

[0079] Aspect 5. The method of any one of Aspects 1 to 4, wherein the alloy comprises a 6xxx aluminum alloy.

[0080] Aspect 6. The method of any one of aspects 1 to 5, wherein the alloy comprises a 6xxx Al-Si-Mg-Cu aluminum alloy.

[0081] Aspect 7. The method according to any one of aspects 1 to 6, further comprising:

[0082] The resulting alloy is obtained,

[0083] The resulting alloy has improved intergranular corrosion (IGC) resistance.

[0084] Aspect 8. The method according to any one of aspects 1 to 7, wherein the first temperature is 200°C to 210°C.

[0085] Aspect 9. The method according to any one of aspects 1 to 8, wherein the first duration is from 5 minutes to 20 minutes.

[0086] Aspect 10. The method according to any one of aspects 1 to 9, wherein the second temperature is 150°C to 200°C.

[0087] Aspect 11. The method according to any one of aspects 1 to 10, wherein the second duration is from 30 minutes to 3 hours.

[0088] Aspect 12. A method comprising:

[0089] subjecting the aluminum alloy to a first temperature for a first duration; and

[0090] subjecting the aluminum alloy to a second temperature for a second duration,

[0091] wherein the first temperature is higher than the second temperature,

[0092] The first duration is from 5 minutes to 20 minutes.

[0093] Aspect 13. The method according to aspect 12, wherein the first temperature is 200°C to 210°C.

[0094] Aspect 14. The method according to any one of aspects 12 to 13, wherein the second temperature is 150°C to 200°C.

[0095] Aspect 15. The method according to any one of aspects 12 to 14, wherein the second duration is from 30 minutes to 3 hours.

[0096] The terms used herein are intended to describe embodiments and are not intended to be limiting. The terms "a", "an" and "the" also include plural forms unless otherwise expressly indicated. When used in this specification, the terms "include" and / or "comprise" specify the presence of stated features, integers, steps, operations, elements and / or parts, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements and / or parts. As used herein, the term "based on" is not exclusive and allows for additional factors that are not described, unless the context clearly specifies otherwise. In addition, the meaning of "in" includes "in" and "on".

[0097] It should be understood that changes may be made in detail, especially in the materials of construction employed and the shapes, sizes and arrangements of parts without departing from the scope of the disclosure. The specification and described embodiments are examples, with the true scope and spirit of the disclosure being indicated by the following claims.

Claims

1. A method comprising: subjecting the alloy to a first temperature for a first duration, wherein the first temperature is greater than the age hardening temperature of the alloy and less than the solution heat treatment temperature; and The alloy is subjected to a second temperature for a second duration.

2. The method according to claim 1, further comprising: Prior to subjecting the alloy to the first temperature, the alloy is subjected to a solution heat treatment at the solution heat treatment temperature. The method of claim 1 , wherein the second temperature is an age hardening temperature.

4. The method of claim 1, wherein the alloy comprises a solution heat treated and quenched alloy.

5. The method of claim 1, wherein the alloy comprises a 6xxx aluminum alloy.

6. The method of claim 1, wherein the alloy comprises a 6xxx Al-Si-Mg-Cu aluminum alloy.

7. The method according to any one of claims 1 to 6, further comprising: The resulting alloy is obtained, The resulting alloy has improved intergranular corrosion (IGC) resistance. The method according to claim 1 , wherein the first temperature is 200° C. to 210° C.

9. The method of claim 1, wherein the first duration is from 5 minutes to 20 minutes.

10. The method of claim 1, wherein the second temperature is 150°C to 200°C. The method of claim 1 , wherein the second duration is from 30 minutes to 3 hours.

12. A method comprising: subjecting the aluminum alloy to a first temperature for a first duration; and subjecting the aluminum alloy to a second temperature for a second duration, wherein the first temperature is higher than the second temperature, The first duration is from 5 minutes to 20 minutes.

13. The method of claim 12, wherein the first temperature is 200°C to 210°C. The method according to claim 12 , wherein the second temperature is 150° C. to 200° C.

15. The method of claim 12, wherein the second duration is from 30 minutes to 3 hours.

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