Aluminum alloy with improved strength and ductility

Abstract

The present disclosure relates to an aluminum alloy with improved strength and ductility. The aluminum alloy composition of the present disclosure achieves an excellent combination of strength / ductility as compared with existing Al-Mg-Si alloys. The aluminum alloy contains, by weight percent, 0.45 to 0.60 Si; ≤0.3 Fe; 0.30 to 0.65 Cu; 0.71 to 0.90 Mg; ≤0.20 Mn; ≤0.12 Cr, and the balance aluminum and unavoidable impurities.

Description

Technical Field

[0001] Cross - Reference to Related Applications This application claims priority to U.S. Provisional Patent Application No. 63 / 364,891, filed May 18, 2022, the entire content of which is incorporated herein by reference.

[0002] The present disclosure relates to the field of aluminum alloys, such as Al - Mg - Si alloys, particularly aluminum alloys useful in the automotive industry.

Background Art

[0003] Aluminum alloys are used in the automotive industry because they have desirable mechanical properties suitable for the automotive industry. In automotive extrusion applications, it is desirable to increase strength in order to enhance energy absorption and to reduce the wall thickness of parts to reduce the vehicle weight of the automobile. Good ductility is also required to accommodate plastic deformation during part forming operations and to withstand severe plastic deformation during collisions without generating cracks that could limit energy absorption. In existing Al - Mg - Si extrusion alloys, strength can be increased by increasing the concentrations of the major elements Mg and Si, but generally, increasing strength always comes with a loss of ductility measured by bend tests or fracture strain.

Summary of the Invention

[0004] It is desirable to produce an aluminum alloy with increased strength without sacrificing ductility, particularly for use in the automotive industry. In one aspect, an aluminum alloy is provided that contains, by weight percent, 0.45 - 0.60 Si; ≤0.3 Fe; 0.30 - 0.65 Cu; 0.71 - 0.90 Mg; ≤0.20 Mn; ≤0.12 Cr, and the balance aluminum and unavoidable impurities. In some embodiments, the unavoidable impurities constitute less than 0.1 weight percent of the aluminum alloy, and each unavoidable impurity is present at a maximum of 0.05 weight percent. In some embodiments, the unavoidable impurities include ≤0.05 weight percent Ni. In some embodiments, the unavoidable impurities include ≤0.05 weight percent Zn. In some embodiments, the unavoidable impurities include ≤0.05 weight percent Ti. In some embodiments, the unavoidable impurities include ≤0.05 weight percent B. In some embodiments, the unavoidable impurities include ≤0.05 weight percent V. In some embodiments, the aluminum alloy contains 0.50 - 0.59 Si. In some embodiments, the aluminum alloy contains ≤0.25 Fe. In some embodiments, the aluminum alloy contains 0.36 - 0.61 Cu. In some embodiments, the aluminum alloy contains 0.74 - 0.85 Mg. In some embodiments, the aluminum alloy contains at least 0.10 Fe. In some embodiments, the aluminum alloy contains ≤0.05 Mn. In some embodiments, the aluminum alloy contains ≤0.05 Cr. In some embodiments, at least one of Cr or Mn is at least 0.05. In some embodiments, at least one of Cr or Mn is greater than 0.05. In some embodiments, the combined concentration of Cr and Mn is at least 0.15 weight percent. In some embodiments, the aluminum alloy further contains a grain refiner.

[0005] In one aspect, an aluminum product is provided that includes the aluminum alloy of the present disclosure. In some embodiments, the aluminum product has a recrystallized grain structure. Those skilled in the art will, by reading the present disclosure, appreciate many additional features and combinations related to the improvement of the present invention.

[0006] Next, refer to the accompanying drawings.

Brief Description of the Drawings

[0007]

Figure 1

Figure 2

Figure 3

Figure 4

Modes for Carrying Out the Invention

[0008] The present disclosure relates to aluminum alloys with improved strength and ductility. The aluminum alloy compositions of the present disclosure achieve an excellent strength / ductility combination compared to existing Al-Mg-Si alloys. The aluminum alloys of the present disclosure provide an excellent strength / ductility combination compared to existing medium-strength Al-Mg-Si alloys such as AA6061, 6005A, and AA6008. Furthermore, the aluminum alloys of the present invention may also exhibit an excellent or equivalent strength / ductility combination compared to the non-recrystallized AA6082 alloy. This aluminum alloy is particularly suitable for applications that require a yield strength of over 290 MPa, and in some cases over 300 MPa, such as automotive applications and parts.

[0009] As provided herein, the aluminum alloys included contain, by weight percent, 0.45 - 0.60 Si; ≤0.3 Fe; 0.30 - 0.65 Cu; 0.71 - 0.90 Mg; ≤0.20 Mn; ≤0.12 Cr, and the balance of aluminum and unavoidable impurities.

[0010] The Al-Mg-Si alloys of the present disclosure surprisingly achieve a combination of improved strength and ductility by the addition of one or more of Mn or Cr, each within a range of up to 0.20 wt% and up to 0.12 wt%, respectively, in combination with an increased Cu concentration within the range of 0.30 to 0.65 wt%. Thus, the aluminum alloys of the present disclosure contain, in weight percent relative to the total weight of the alloy composition, 0.45 to 0.60 Si, up to 0.30 Fe, 0.30 to 0.65 Cu, 0.71 to 0.90 Mg, up to 0.20 Mn, and up to 0.12 Cr, along with the balance of aluminum and unavoidable impurities.

[0011] In one embodiment, the Al-Mg-Si alloys of the present disclosure contain ≦0.05 Mn, ≦0.05 Cr, with at least one of Cr or Mn being at least 0.05; at least one of Cr or Mn being greater than 0.05; or the combined concentration of Cr and Mn being at least 0.15 wt%.

[0012] The aluminum alloys of the present disclosure have a Si content, in weight percent relative to the total weight of the aluminum alloy, of 0.45 to 0.60, 0.46 to 0.60, 0.47 to 0.60, 0.48 to 0.60, 0.49 to 0.60, 0.50 to 0.60, 0.51 to 0.60, 0.52 to 0.60, 0.45 to 0.59, 0.46 to 0.59, 0.47 to 0.59, 0.48 to 0.59, 0.49 to 0.59, 0.50 to 0.59, 0.51 to 0.59, 0.52 to 0.59, 0.45 to 0.58, 0.46 to 0.58, 0.47 to 0.58, 0.48 to 0.58, 0.49 to 0.58, 0.50 to 0.58, 0.51 to 0.58, 0.52 to 0.58, 0.49 to 0.57, 0.50 to 0.56, 0.51 to 0.55, or 0.52 to 0.54. Silicon, in combination with Mg and Cu, improves the strength of the Al alloy by causing precipitation hardening and also promotes the formation of Al-Mn-Fe-Si dispersoid particles that can prevent the localization of slip.

[0013] The aluminum used to produce the alloy of the present invention may be primary aluminum alloy or recycled material. Fe is a natural impurity of primary aluminum and can also be found at increased levels in recycled materials, and the claimed scope reflects the use of materials from these two sources. The aluminum alloy of the present disclosure has an Fe content of up to 0.3, up to 0.25, up to 0.20, up to 0.19, up to 0.18, up to 0.17, 0.10 to 0.30, 0.10 to 0.25, 0.10 to 0.22, 0.10 to 0.20, 0.12 to 0.19, 0.13 to 0.18, or 0.14 to 0.17, by weight percent relative to the total weight of the aluminum alloy. The amount of Fe is limited to up to 0.3, preferably up to 0.25, more preferably up to 0.20, in order to avoid any adverse effects on the mechanical properties of the aluminum alloy. Fe has low solubility in aluminum and usually forms Al-Fe-Si type intermetallic compounds or constituent particles during the casting and homogenization processes, which can be harmful to the surface finish of the profile and, when present at high concentrations, can be harmful to ductility. For this reason, an upper limit of the Fe content, as described herein, for example up to 0.3, up to 0.25, or up to 0.2 is desirable.

[0014] The aluminum alloy of the present disclosure has a Cu content of 0.30 to 0.65, 0.31 to 0.65, 0.32 to 0.65, 0.33 to 0.65, 0.34 to 0.65, 0.35 to 0.65, 0.36 to 0.65, 0.37 to 0.65, 0.38 to 0.65, 0.30 to 0.64, 0.30 to 0.63, 0.30 to 0.62, 0.30 to 0.61, 0.30 to 0.60, 0.30 to 0.59, 0.31 to 0.64, 0.32 to 0.64, 0.33 to 0.63, 0.34 to 0.63, 0.35 to 0.62, 0.36 to 0.61, 0.37 to 0.60, 0.38 to 0.59, or 0.45 to 0.65, by weight percent based on the total weight of the aluminum alloy. In some embodiments, the Cu content can be 0.33 to 0.44, 0.34 to 0.43, 0.35 to 0.42, 0.36 to 0.41, 0.37 to 0.40, or 0.38 to 0.39, by weight percent. In some embodiments, the Cu content can be 0.54 to 0.64, 0.55 to 0.63, 0.56 to 0.62, 0.57 to 0.61, 0.58 to 0.60, or 0.59, by weight percent. Cu can promote the formation of Al-Mg-Si-Cu age precipitates such as Q” or Q’ that can improve the dispersion of slip during plastic deformation in addition to the normal MgSi precipitates.

[0015] The aluminum alloy of the present disclosure has an Mg content of 0.71 to 0.90, 0.72 to 0.90, 0.73 to 0.90, 0.74 to 0.90, 0.75 to 0.90, 0.76 to 0.90, 0.77 to 0.90, 0.78 to 0.90, 0.71 to 0.89, 0.71 to 0.88, 0.71 to 0.87, 0.71 to 0.86, 0.71 to 0.85, 0.71 to 0.84, 0.71 to 0.83, 0.71 to 0.82, 0.71 to 0.81, 0.72 to 0.89, 0.73 to 0.88, 0.74 to 0.87, 0.74 to 0.86, 0.75 to 0.85, 0.75 to 0.84, 0.76 to 0.83, 0.73 to 0.86, 0.74 to 0.85, 0.77 to 0.85, 0.77 to 0.83, or 0.78 to 0.82, by weight percent based on the total weight of the aluminum alloy. The main role of magnesium is to provide precipitation hardening in combination with Si and Cu.

[0016] The aluminum alloy of the present disclosure has an Mn content of up to 0.20, up to 0.19, up to 0.18, up to 0.17, up to 0.16, up to 0.15, up to 0.14, up to 0.13, up to 0.12, up to 0.11, up to 0.10, up to 0.09, up to 0.08, up to 0.07, up to 0.06, up to 0.05, up to 0.04, up to 0.03, 0.03 to 0.20, 0.03 to 0.19, 0.03 to 0.18, 0.03 to 0.17, 0.03 to 0.16, 0.03 to 0.15, 0.03 to 0.14, 0.03 to 0.13, 0.03 to 0.12, 0.03 to 0.11, 0.03 to 0.10, 0.03 to 0.09, 0.05 to 0.20, 0.05 to 0.19, 0.05 to 0.18, 0.05 to 0.17, 0.05 to 0.16, 0.05 to 0.15, 0.05 to 0.14, 0.05 to 0.13, 0.05 to 0.12, 0.05 to 0.11, 0.05 to 0.10, 0.05 to 0.09, 0.06 to 0.12, 0.07 to 0.12, 0.08 to 0.12, 0.07 to 0.11, or 0.08 to 0.10, by weight percent based on the total weight of the aluminum alloy. In some embodiments, the minimum content of Mn is at least 0.03 wt%, at least 0.04 wt%, at least 0.05 wt%, or more than 0.05 wt%. Mn can contribute to the strength of the Al alloy by dispersion particle strengthening and solid solution hardening. Mn promotes the formation of Al-Mn-Fe-Si submicron dispersion particles during the homogenization process. These dispersion particles act to disperse slip during the plastic deformation process, thereby delaying the occurrence of internal stress concentration and fracture phenomena. Mn also improves the extrusion formability by promoting the transformation of the β component phase Al-(Fe,Mn)Si to the α phase. However, an excessive amount of dispersion particles may increase the flow stress of the alloy at the extrusion temperature, affect the extrusion speed adversely, and inhibit recrystallization, possibly forming a coarse recrystallized grain structure or a non-recrystallized grain structure.

[0017] The aluminum alloy of the present disclosure has a Cr content of up to 0.12, up to 0.11, up to 0.10, up to 0.09, up to 0.08, up to 0.07, up to 0.06, 0.03 to 0.12, 0.03 to 0.11, 0.03 to 0.10, 0.03 to 0.09, 0.05 to 0.12, 0.05 to 0.11, 0.05 to 0.10, 0.05 to 0.09, 0.06 to 0.12, 0.06 to 0.11, 0.06 to 0.10, 0.06 to 0.09, or 0.07 to 0.08, by weight percent based on the total weight of the aluminum alloy. In some embodiments, the minimum Cr content is at least 0.03 wt%, at least 0.04 wt%, at least 0.05 wt%, or greater than 0.05 wt%. The dispersoid particles formed by the addition of Cr and Mn have a similar cubic crystal structure with similar lattice constants and dissolve in each other such that the two elements are exchangeable to some extent.

[0018] In some embodiments, at least one of Mn or Cr is intentionally added at a minimum content of, for example, at least 0.03 wt%, at least 0.04 wt%, at least 0.05 wt%, or more than 0.05 wt%. In some embodiments, only one of Mn or Cr is intentionally added at a minimum content of, for example, at least 0.03 wt%, at least 0.04 wt%, at least 0.05 wt%, or more than 0.05 wt%. In some embodiments, both Mn and Cr are intentionally added at respective minimum contents of, for example, at least 0.03 wt%, at least 0.04 wt%, at least 0.05 wt%, or more than 0.05 wt%. In some embodiments, the content of Mn + Cr is defined to be at least 0.05, at least 0.06, at least 0.07, at least 0.08, at least 0.09, at least 0.10, at least 0.11, at least 0.12, at least 0.13, at least 0.14, at least 0.15, at least 0.16, at least 0.17, at least 0.18, at least 0.19, 0.05 - 0.20, 0.06 - 0.20, 0.07 - 0.20, 0.08 - 0.20, 0.09 - 0.20, 0.10 - 0.20, 0.05 - 0.19, 0.06 - 0.19, 0.07 - 0.19, 0.08 - 0.18, 0.09 - 0.18, or 0.10 - 0.17. In some embodiments, Cr may be used instead of Mn, and vice versa. The equivalent content of Cr to Mn is approximately 1:2. For example, 0.07 Cr may be equivalent to 0.15 Mn. Thus, in some embodiments, when the Cr content is at least 0.05 wt%, the alloy does not contain intentionally added Mn. In other embodiments, when Mn is at least 0.1 wt%, the alloy does not contain Cr.

[0019] The weight percent concentrations in the aluminum alloy are provided with the balance being aluminum and unavoidable impurities. In some embodiments, each of the unavoidable impurities is present at a maximum of 0.05 (0.03 in some embodiments), and the total of the unavoidable impurities constitutes less than 0.10. In some embodiments, as used herein, the term "unavoidable impurities" is to be understood to mean those that are not intentionally added.

[0020] In some embodiments, the unavoidable impurities include Ni at a concentration of 0.05 or less, 0.04 or less, 0.03 or less, 0.02 or less, 0.01 or less. Ni has very low solubility in aluminum and forms undesirable constituent particles. Ni can be present as an impurity from the anode in the reduction process.

[0021] In some embodiments, the unavoidable impurities include Zn at a concentration of 0.05 or less, 0.04 or less, 0.03 or less, 0.02 or less, 0.01 or less. The presence of Zn can have an adverse effect on the corrosion performance of the alloy. In one embodiment, the unavoidable impurities constitute less than 0.1 wt% of the aluminum alloy, and each unavoidable impurity is present at a maximum of 0.05 wt%.

[0022] In some embodiments, the unavoidable impurities include Ti at a concentration of 0.05 or less, 0.04 or less, 0.03 or less, 0.02 or less, 0.01 or less. In some embodiments, the unavoidable impurities include B at a concentration of 0.05 or less, 0.04 or less, 0.03 or less, 0.02 or less, 0.01 or less.

[0023] In some embodiments, the unavoidable impurities include V at a concentration of 0.05 or less, 0.04 or less, 0.03 or less, 0.02 or less, 0.01 or less. V is detrimental to the extrudability of the aluminum alloy and is generally an impurity resulting from only the aluminum reduction process.

[0024] In some embodiments, the unavoidable impurities include Zr at a concentration of 0.05 or less, 0.04 or less, 0.03 or less, 0.02 or less, 0.01 or less. In some embodiments, the aluminum alloys of the present disclosure comprise, consist essentially of, or consist of any combination of the concentration ranges listed above for Si, Fe, Cu, Mg, Mn, Cr, Mn+Cr, and incidental impurities.

[0025] In some embodiments, the aluminum alloy further includes a grain refiner, such as titanium, titanium boride, or titanium carbide, as desired to solidify the aluminum alloy. In one embodiment, the grain refiner is in the form of Ti, TiB, or TiC. When TiB is used as the grain refiner, the resulting B content in the alloy can be up to 0.05 wt.%. When TiC is used as the grain refiner, the resulting C content in the alloy can be up to 0.01 wt.%. The Ti dissolved in the molten aluminum is dissolved in TiB. 2 / melt interface at TiAl 3 It can promote the formation of a layer, which in turn induces the nucleation of Al grains.

[0026] The present disclosure also provides a method for producing high strength aluminum products using the disclosed aluminum alloy. In a first step, the method includes casting the disclosed aluminum alloy to obtain a cast aluminum product. The casting step may include, for example, direct chill casting, continuous casting, and / or semi-continuous casting. Properti continuous casting may be used, which may be a wheel-belt casting process or a track-belt casting process. The track-belt process replaces the casting wheel with a number of copper blocks. Other options may be used, including twin roll casters. Twin roll casters have two rolls that rotate to continuously advance the molded product. The rolls may be cooled to aid in the solidification of the molten aluminum alloy. Further options include block casters with blocks configured to function as belts. The blocks may be cooled to aid in the solidification of the molten aluminum alloy.

[0027] In the second step, the cast aluminum product is extruded to form an extruded aluminum product. During the extrusion process, the aluminum alloy is heated to a temperature at which the alloy becomes malleable. A press container may be used in front of the die orifice. Pressure is applied using a hydraulic ram to push the aluminum alloy and fill the container, and it can be formed into the desired shape through the die. After hot deformation (i.e., extrusion or propeller hot rolling), the aluminum alloy can be actively cooled by using a cooling fan and / or water spray or immersion water quenching. In a preferred embodiment, a cooling rate of 20 °C / second from 500 to 300 °C is used. Most automotive extruded products are hollow in order to improve rigidity and crush performance. Thus, in some embodiments, the extruded product is a hollow extruded product such as a hollow automotive extruded product. Water cooling at the press outlet, which is usually spray cooling, is generally beneficial for ductility compared to, for example, air cooling, and is thus preferred. The improvement with water cooling compared to air cooling may be related to changes in the microstructure at the grain boundaries.

[0028] A fully recrystallized grain structure provides advantages in automotive applications compared to a non-recrystallized grain structure (typically with a coarse recrystallized surface layer). These include a reduced sensitivity of strength to the press cooling rate, no occurrence of orange peel on the surface that can be a starting point for fatigue and corrosion, and local extrusion weld line ductility. In addition, when the levels of dispersion particle-forming elements such as Mn and Cr required to form a non-recrystallized grain structure are high, it can typically result in inferior extrusion formability and strength cooling sensitivity. In some embodiments, the aluminum alloy of the present invention achieves a fully recrystallized grain structure to benefit from these advantages, and the fully recrystallized structure is a feature of the product.

[0029] In one embodiment, the method further includes heat treating or homogenizing the cast aluminum product after casting and before extrusion. The heat treatment conditions can be a duration of at least about 1 hour, at least about 2 hours, at least about 3 hours, at least about 4 hours, or at least about 5 hours at a temperature of about 450 to about 600 °C, about 500 to about 600 °C, about 550 to about 590 °C, or about 560 to about 580 °C. In some embodiments, the aluminum product is a billet for extrusion.

[0030] The strength and ductility of aluminum alloys can be specified in various suitable ways. However, the elongation to failure in a tensile test is not a useful parameter for predicting impact performance. On the other hand, the ductility of an extruded product can be evaluated by the bending test (VDA 238-100) of the German Automobile Industry Association in the extrusion direction or in the direction transverse to the extrusion direction. In such a bending test, the bending applied during bending in axial or lateral crush, or the strain applied during mechanical joining such as self-piercing rivets, can be simulated. The true fracture strain (Ln(initial cross-sectional area / final fracture area)) measured in a tensile test is a useful measure of ductility in such applications.

[0031] In some embodiments, the aluminum products of the present disclosure have a tensile strength (UTS) of at least 290, at least 295, at least 300, at least 305, at least 310, at least 315, at least 320, at least 325, at least 330, or at least 335 MPa. In some embodiments, the aluminum products of the present disclosure have a yield strength of at least 260 MPa, at least 265 MPa, at least 270 MPa, greater than 275 MPa, at least 280 MPa, at least 285 MPa, at least 290 MPa, at least 295 MPa, at least 300 MPa, or at least 305 MPa. In some embodiments, the aluminum products of the present disclosure have a longitudinal VDA bend angle of at least 50°, at least 55°, at least 60°, or at least 65° along the longitudinal direction. In some embodiments, the aluminum products of the present disclosure have a transverse VDA bend angle of at least 25°, 26°, 27°, 28°, 29°, or 30° with respect to a thickness of 2.5 mm. In some embodiments, the aluminum products of the present disclosure have a true fracture strain of at least 0.40, at least 0.41, at least 0.42, or at least 0.43 with respect to a thickness of 2.5 mm.

[0032] The present disclosure will be more readily understood by reference to the following examples. Examples The alloy compositions listed in Table 1 were directly chill cast (DC cast) as billets with a diameter of 101 mm. Before casting, a 5% Ti-1% B grain refiner was added. In some cases, additional Ti was added to the furnace to enhance the grain refiner. Alloys A - D, H, and I were homogenized at 580 °C for 2 hours, while alloys F, G, and J were homogenized at 560 °C for 3 hours due to their low solidus. After homogenization, all alloys were forced air cooled from 500 °C to 200 °C at a rate of 450 °C / hour. Alloys E and K, corresponding to typical commercially available AA6082 and AA6061 alloy variants, were given an industrial homogenization cycle. The billets were extruded into a 50×20×2.5 mm hollow box profile using a billet preheat temperature of 500 °C and an extrusion exit speed of 10 - 11 m / min. The die was constructed such that the extrusion weld was located on the 20 mm face of the profile so that the properties could be evaluated on a 50 mm wide face away from the extrusion weld. After discharge from the die, the profile was water spray cooled from 500 °C to 300 °C at a rate of 150 °C / second. The cooling rate was measured using a clip-on contact thermocouple attached to a waterproof high-frequency logger with a WiFi transmitter. The cooled profile was stretched to impart a 0.5% permanent strain and, after a 24-hour delay at room temperature, solution heat treated at 177 °C for 8 hours. Tensile tests were performed longitudinally in accordance with ASTM E8, and the fracture cross-sectional area projected in the tensile direction was measured using image analysis techniques so that the true fracture strain could be calculated using the formula Ln(initial cross-sectional area / final fracture area). The larger the value of the fracture strain, the better the bending and ductility. The VDA bend test was performed longitudinally (the bending axis is perpendicular to the extrusion direction) and transversely (the bending axis is parallel to the extrusion direction) with a punch radius of 0.4 mm, a roller spacing of twice the material thickness, i.e., 5 mm, and a load drop of 60 N. After removing the load, the complementary angle of the bend angle was measured, indicating that the larger the bend angle, the better the ductility or bendability.

[0033]

Table 1

[0034] The compositions in Table 1 are classified in ascending order of Mg concentration. Alloys A, B, and D were within the composition range of AA6008, an alloy developed for automotive applications and widely used. Vanadium required in the AA6008 specification was intentionally added to these. Alloy C was similar to AA6008 but without intentional addition of V. Alloys F and G corresponded to the composition range of widely used AA6005A. In alloys H, I, and J, the Cu level was increased and the additions of Mn and Cr were controlled.

[0035] The microstructure of the extruded products was evaluated metallographically. Typical grain structures revealed by Barker electrolytic etching and observation under polarization are shown in FIGS. 1A, 1B, and 1C. The commercially available alloy AA6082 (alloy E) mainly had a non-recrystallized grain structure with a coarse-grained recrystallized surface layer. In contrast, all the other alloys exhibited a fully recrystallized grain structure, which is desirable in this type of product to avoid problems associated with coarse surface grains and for improved local ductility at the extrusion weld line. Examples of the recrystallized structures of alloy K (AA6061) and J are shown in FIGS. 1A and 1B.

[0036] Table 2 shows the results of the mechanical properties of each composition. In the table, VDA-L is the longitudinal bending angle test, VDA-T is the transverse bending angle test, El is the elongation, Ef is the true fracture strain, YS is the yield strength, and UTS is the tensile strength.

[0037] [Table 2]

[0038] Figure 2 is a plot of the longitudinal VDA bend angle as a function of yield strength after artificial aging. The data points are labeled with the alloy IDs from Table 1. Variants of AA6008 (A, B, D), V-free AA6008 (C), and AA6005A (F, G), along with commercially available AA6061 (K), show combinations of strength and ductility that fall within a band labeled "baseline strength and ductility" where ductility decreases approximately linearly with increasing yield strength. In contrast, alloys H, I, and J with controlled additions of Cu, Mn, and / or Cr show improved strength / ductility combinations compared to the baseline and also show equivalent or improved performance compared to the non-recrystallized commercially available AA6082 alloy (E). Figure 3 shows a similar plot of the transverse VDA angle as a function of yield strength. The transverse results show a similar separation between the compositions of the present invention and the baseline material. As shown by comparison of Figures 2 and 3, the bend angle measured transverse to the extrusion direction is typically smaller than the bend angle measured longitudinally. A non-recrystallized grain structure, such as that observed in commercially available AA6082 (alloy E), typically exhibits superior transverse bend angles compared to recrystallized materials. However, alloys H, I, and J of the present invention also show here a combination of strength and ductility that is superior to the baseline alloys when tested transversely and also show strength and ductility similar to alloy E.

[0039] Figure 4 represents a plot of the true fracture strain from a tensile test, which is a third measure of ductility, as a function of yield strength. Similar to the longitudinal VDA results, the compositions of baseline AA6008, AA6005A, and AA6061 show a tendency for fracture strain to decrease with increasing yield strength. Alloys H, I, and J of the present invention show combinations of strength and fracture strain that are superior to the baseline and also show performance similar to the non-recrystallized commercially available AA6082 (E).

[0040] Although the present disclosure has been described in connection with its specific embodiments, it is to be understood that the disclosure is capable of further modifications and this application is intended to cover any variations, uses, or adaptations of the disclosure that fall within the scope of known or customary practice in the art and that depart from the essential features of the disclosure as set forth in the foregoing description and as defined in the following appended claims.

Claims

1. In weight percentage, Si in the range of 0.45 to 0.60; Fe ≤ 0.3; Cu between 0.30 and 0.65; Mg 0.71–0.90; Mn ≤ 0.20; Cr ≤ 0.12; and Remaining aluminum and unavoidable impurities, Aluminum alloys, including aluminum alloys.

2. The aluminum alloy according to claim 1, wherein the aforementioned unavoidable impurities constitute less than 0.1% by weight of the aluminum alloy, and each unavoidable impurity is present in a maximum of 0.05% by weight.

3. The aluminum alloy according to claim 1 or 2, wherein the aforementioned unavoidable impurities include ≤0.05% by weight of Ni.

4. The aluminum alloy according to claim 1 or 2, wherein the aforementioned unavoidable impurities include ≤0.05% by weight of Zn.

5. The aluminum alloy according to claim 1 or 2, wherein the unavoidable impurities include ≤0.05% by weight of Ti.

6. The aluminum alloy according to claim 1 or 2, wherein the aforementioned unavoidable impurity contains ≤0.05% by weight of B.

7. The aluminum alloy according to claim 1 or 2, wherein the aforementioned unavoidable impurity contains ≤0.05% by weight of V.

8. The aluminum alloy according to claim 1 or 2, comprising 0.50 to 0.59 Si.

9. The aluminum alloy according to claim 1 or 2, comprising Fe ≤ 0.

25.

10. The aluminum alloy according to claim 1 or 2, comprising 0.36 to 0.61 units of Cu.

11. The aluminum alloy according to claim 1 or 2, comprising 0.74 to 0.85 mg of Mg.

12. The aluminum alloy according to claim 1 or 2, comprising at least 0.10 Fe.

13. The aluminum alloy according to claim 1 or 2, comprising Mn ≤ 0.

05.

14. The aluminum alloy according to claim 1 or 2, comprising ≤0.05 Cr.

15. The aluminum alloy according to claim 1 or 2, wherein at least one of Cr or Mn is at least 0.

05.

16. The aluminum alloy according to claim 1 or 2, wherein at least one of Cr or Mn is greater than 0.

05.

17. The aluminum alloy according to claim 1 or 2, wherein the combined concentration of Cr and Mn is at least 0.15% by weight.

18. Furthermore, the aluminum alloy according to claim 1 or 2, comprising a crystal refiner.

19. An aluminum product comprising the aluminum alloy described in claim 1 or 2.

20. The aluminum product according to claim 19, having a recrystallized grain structure.

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