Aluminum Extrusion Alloy

Abstract

The aluminum alloy contains Si and Mg in amounts (by weight) within a quadrilateral defined by the following coordinates on an Mg / Si plot: I: 1.15Si, 0.70Mg, II: 0.95Si, 0.55Mg, III: 0.75Si, 0.65Mg, and IV: 0.95Si, 0.85Mg. The alloy also contains, in weight percent, Mn: 0.40-0.80, Fe: 0.25 max, Cr: 0.05-0.18, Cu: 0.30-0.90, Ti: 0.05 max, Zr: 0.03 max, Zn: 0.03 max, B: 0.01 max, with the balance being aluminum and unavoidable impurities, each up to 0.05 wt% and totaling up to 0.15 wt%.

Description

Technical Field

[0001] (Cross - Reference to Related Applications) This application claims the priority and benefit of U.S. Provisional Patent Application No. 62 / 774,661, filed on December 3, 2018, which is hereby incorporated by reference in its entirety.

[0002] The present disclosure relates to aluminum alloys suitable for use in extrusion, and more specifically, in one aspect, to an Al - Mg - Si - Cu - Mn - Cr extrusion alloy having high strength and ductility.

Background Art

[0003] Aluminum extrusion alloys are often used in automotive applications, and higher strength extrusion alloys having a yield strength of at least 350 MPa may be desired or required for this purpose. Many existing commercially available alloys such as AA6066 and AA6056 are capable of this strength level, but these alloys exhibit a decrease in extrudability compared to standard extrusion alloys. Also, in such high - strength alloys, ductility and collapse performance become problems. Therefore, there is a need for an aluminum extrusion alloy that has good extrudability and ductility and can stably achieve a yield strength of 350 MPa or more. To ensure that commercially produced alloys consistently meet the minimum yield strength, it is desirable for the average or typical yield strength value to significantly exceed the minimum target, such as at least 20 MPa, taking into account the strength variation for each sample. For example, to stably meet a target minimum strength of 350 MPa, an average yield strength of 370 MPa or more is desirable.

Summary of the Invention

Problems to be Solved by the Invention

[0004] The present disclosure is provided to address this and other needs in existing aluminum extrusion alloys. A complete description of the features and advantages of the present invention is left to the following detailed description, which proceeds with reference to the accompanying drawings.

Means for Solving the Problem

[0005] Aspects of the present disclosure relate to an aluminum extrusion alloy containing Si and Mg in weight percent in an amount within a quadrilateral defined by the following coordinates on an Mg / Si plot. I 1.15 Si, 0.70 Mg II 0.95 Si, 0.55 Mg III 0.75 Si, 0.65 Mg IV 0.95 Si, 0.85 Mg Here, the alloy further contains the following in weight percent: Mn 0.40 - 0.80 Fe at most 0.25 Cr 0.05 - 0.18 Cu 0.30 - 0.90 Ti at most 0.05 Zr at most 0.03 Zn at most 0.03 B at most 0.01 The balance is aluminum and unavoidable impurities, and the unavoidable impurities are each in an amount up to 0.05 wt% and in total up to 0.15 wt%.

[0006] According to one aspect, Mg and Si are present at an Mg / Si ratio of at least 0.69 and / or at most 0.88.

[0007] According to another aspect, the alloy contains excess Mg, and in one embodiment, contains up to 0.40 wt% of said excess Mg as defined herein.

[0008] According to a further aspect, the alloy has a mainly non-recrystallized microstructure after homogenization, extrusion, and artificial aging.

[0009] According to yet another aspect, the alloy has a yield strength of at least 350 MPa and a tensile elongation of at least 8% after homogenization, extrusion, and artificial aging. In one embodiment, the alloy can have a yield strength of at least 370 MPa.

[0010] According to yet another aspect, the alloy contains Mg in an amount of 0.60 to 0.80 wt% and Si in an amount of 0.85 to 1.10 wt%. In one embodiment, the Mg content may be 0.70 to 0.80 wt% and the Si content may be 0.85 to 0.95 wt%.

[0011] According to yet another aspect, the amounts of Si and Mg are within the quadrilateral defined by the following coordinates on the Mg / Si plot, in weight percent. I 1.15 Si, 0.70 Mg II 0.95 Si, 0.55 Mg III’ 0.80 Si, 0.65 Mg IV’ 0.95 Si, 0.80Mg.

[0012] An additional aspect of the present disclosure is, in weight percent,[[]] Mg 0.60 - 0.80 Si 0.85 - 1.10 Mn 0.40 - 0.80 Fe max 0.25 Cr 0.05 - 0.18 Cu 0.30 - 0.90 Ti max 0.05 Zr max 0.03 Zn max 0.03 B max 0.01 including, with the balance being aluminum and unavoidable impurities, the unavoidable impurities being in amounts of up to 0.05 each and up to 0.15 in total, an aluminum extrusion alloy. The alloy may include any other aspect described hereinabove.

[0013] A further aspect of the present disclosure relates to an extruded product formed at least in part from the aluminum alloy described herein.

[0014] Yet another aspect of the present disclosure relates to a method that includes, for example, casting or otherwise forming a billet of an aluminum alloy described herein using direct chill casting or other continuous casting techniques, then homogenizing the billet, and extruding the homogenized billet to form an extruded product. The homogenization can be performed by heating the billet at a temperature of 540 to 580 °C for 2 to 10 hours and then cooling the homogenized billet at a cooling rate of 300 °C / hour or more.

[0015] Other features and advantages of the present disclosure will become apparent from the following description in conjunction with the accompanying drawings.

Brief Description of the Drawings

[0016] To provide a more complete understanding of the present disclosure, an example will be described with reference to the accompanying drawings.

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Modes for Carrying Out the Invention

[0017] Although the present invention is susceptible to many different forms of embodiments, it should be considered as an exemplification of the principles of the present invention, and it is not intended to limit the broad aspects of the present invention to the illustrated embodiments. Understanding this, exemplary embodiments of the present invention are shown in the drawings and will be described in detail herein. It should be understood that other specific structural features can be utilized and modifications can be made without departing from the scope of the present invention.

[0018] Aspects of the present disclosure relate to aluminum alloys useful for extrusion applications having various alloying elements including Mg, Si, Fe, Mn, Cu, and Cr. The alloys described herein may also be useful in forging applications and may provide beneficial properties in such applications. All compositional ratios listed herein are by weight percent unless otherwise specified.

[0019] In one embodiment, the alloy may include magnesium in an amount of 0.60 - 0.80 wt% or 0.6 - 0.8 wt% and silicon in an amount of 0.85 - 1.10 wt%. Mg and Si in this composition may also be present, in one embodiment, at a Mg / Si ratio (wt%) of at least 0.69. The Mg / Si ratio may have, additionally or alternatively, an upper limit of 0.88 in one embodiment or 0.85 in another embodiment. Alloys having too high a Mg / Si ratio may have poor extrudability in terms of quantity, and alloys having a higher Mg / Si ratio may not obtain sufficient extrudability. In another embodiment, the alloy may include magnesium in the range of 0.70 - 0.80 wt% and silicon in the range of 0.85 - 0.95 wt%.

[0020] In another embodiment, the alloy may include amounts of magnesium and silicon defined within a quadrilateral defined by the following coordinates on the Mg / Si plot as shown in FIG. 1. I: 1.15 Si, 0.70 Mg II: 0.95 Si, 0.55 Mg III: 0.75 Si, 0.65 Mg IV: 0.95 Si, 0.85 Mg

[0021] In a further embodiment, the alloy may contain amounts of magnesium and silicon defined within a quadrilateral defined by the following coordinates on the Mg / Si plot, as shown in FIG. 1. I: 1.15 Si, 0.70 Mg II: 0.95 Si, 0.55 Mg III’: 0.80 Si, 0.65 Mg IV’: 0.95 Si, 0.80 Mg

[0022] In any of the embodiments herein, the alloy may contain at least some excess magnesium (i.e., excess Mg > 0) as defined by the following formula. Excess Mg = Mg - (Si - (Mn + Fe + Cr) / 3) / 1.16 (all values are in wt%)

[0023] The alloy may contain up to 0.40 wt% excess magnesium in one embodiment and up to 0.35 wt% excess magnesium in another embodiment. Excess Mg, if in too high an amount, may result in poor extrudability, and alloys with more than this excess Mg may not achieve sufficient extrudability.

[0024] The alloy may further contain the following elements in wt%. Mn 0.40 - 0.80 Fe max 0.25 Cr 0.05 - 0.18 Cu 0.30 - 0.90 Ti max 0.05 Zr max 0.03 Zn max 0.03 The balance is aluminum and unavoidable impurities, and the unavoidable impurities may be present in amounts of up to 0.05 wt% each and up to 0.15 wt% in total. In one embodiment, the alloy may contain additional elements not listed.

[0025] Silicon can combine with iron, manganese, and / or chromium in the intermetallic phases in the alloy. Further, sufficient amounts of manganese and chromium can form dispersoid particles that suppress grain recrystallization after extrusion. The iron content of the alloy in one embodiment is at most 0.25 wt%. In another embodiment, the iron content of the alloy may be 0.15 - 0.25 wt%. The chromium content of the alloy in one embodiment is 0.05 - 0.18 wt%. In another embodiment, the chromium content of the alloy may be 0.05 - 0.15 wt%. The manganese content of the alloy in one embodiment is 0.40 - 0.80 wt%, but may alternatively be 0.4 - 0.8 wt%. In another embodiment, the manganese content of the alloy may be 0.40 - 0.55 wt%.

[0026] Copper can increase the strength of the alloy. The copper content of the alloy in the above-described embodiments is 0.30 - 0.90 wt%, but may alternatively be 0.3 - 0.9 wt%. In other embodiments, the copper content of the alloy may be 0.30 - 0.80 wt%, 0.60 - 0.80 wt%, or 0.60 - 0.90 wt%.

[0027] Titanium is added as a grain refiner in one embodiment and may be added together with boron in the form of TiB rods (e.g., 5% Ti, 1% B). Thus, in one embodiment, the alloy may also contain up to 0.01%, or up to 0.005% boron.

[0028] In one embodiment, the alloys according to the aspects and embodiments of this specification can be prepared by forming billets by direct chill casting or other continuous casting methods and then homogenizing the billets. The homogenization can be carried out, for example, at 540 - 580 °C for 2 - 10 hours, and then the billets can be cooled at a rate of 300 °C / hour or more, for example, 300 - 600 °C / hour after homogenization. It is understood that these cooling rates can be measured over a part of the cooling range rather than throughout the overall cooling of the billet (i.e., from the homogenization temperature to the ambient temperature). For example, in one embodiment, the relevant cooling rate can be measured between the temperatures of 500 °C and 200 °C during cooling. Thereafter, the billet can be extruded into an extrusion profile or extruded product that includes, in some applications, at least one concave surface, at least one convex surface, at least one angled corner, and / or at least one internal cavity. The extrusion can be carried out, in one embodiment, by preheating to 470 - 520 °C before extrusion and water quenching at the press exit, for example, by water spray or a standing wave water box, and cooling can be achieved at about 50 - 1000 °C / second. The extruded product may be artificially aged, such as by heating at 160 - 185 °C for 5 - 16 hours, after extrusion. It is understood that in other embodiments, other processes including post - extrusion processing of the extruded product may be used to achieve the desired properties, shape, etc.

[0029] In one embodiment, the extruded products manufactured using the alloys and processing techniques described herein can have a post - extrusion grain structure that is mainly fibrous or non - recrystallized. This mainly fibrous microstructure may have a microstructure in which at least 50% is not recrystallized in one embodiment, or at least 75% is not recrystallized in another embodiment, and this can be over most of the length of the extrusion profile or over the entire length. The non - recrystallized grain structure can improve the yield strength of the alloy after extrusion. In one embodiment, the alloys described herein can achieve a yield strength of at least 350 MPa or at least 360 MPa with a tensile elongation of at least 8%, at least 9%, or at least 10% after extrusion and artificial aging.

[0030] The following are some examples showing the beneficial properties and advantageous performance of the alloys and comparative alloys according to the aspects of the present disclosure.

Examples

[0031] Example 1 The alloy compositions listed in Table 1 representing existing commercially available high-strength AA6XXX alloys were directly chill cast as 101.6 mm diameter ingots, and a 5% Ti-1% B grain refiner was added before casting to ensure a fine casting grain size.

[0032]

Table 1

[0033] The ingots were cut to a billet length of 400 mm and homogenized. The AA6111 and AA6056 billets were homogenized at 560 °C for 2 hours, and the AA6066 billets were homogenized at 545 °C for 4 hours. After homogenization, these billets were cooled at 400 °C / hour.

[0034] These billets were extruded into 40×30×2 mm hollow profiles with a 5 mm external corner radius using a billet temperature of 475 °C and a ram speed of 4 - 6 mm / s. The ram speed was varied to find the maximum speed achievable before surface cracking occurred. This maximum ram speed is reported in Table 2. The extrusion ratio was 32 / 1, and the corresponding exit speed was in the range of 8 - 12 m / min. The extrudates were water quenched at a rate of approximately 1000 °C / second using a standing wave water quenching unit located approximately 2.5 m from the extrusion die. After the extrudates were floor aged at room temperature for 24 hours, they were artificially aged at 175 °C for 8 hours.

[0035] The crushing test was carried out by axially crushing a length of 150 mm to 30 mm at a crosshead speed of 20 mm / s. The load-displacement curve was recorded, and the mean crushing force (MCF) was calculated using an averaging method. The degree of cracking during the crushing test (crushing rating CR) was evaluated on a scale of 1 to 9, where 1 represented a sample without cracks and 9 represented complete disintegration. A longitudinal tensile test was performed, the final fracture cross-sectional area was measured, and the true fracture strain e f was calculated as = -Ln(final area / initial area). The true fracture strain (e f ) has been shown to be a good measure of ductility at high plastic strains. The mechanical properties and crushing test results are also reported in Table 2, where in the table, RX indicates a fully recrystallized grain structure and F indicates a mainly fibrous grain structure. Some of these results are also graphically shown in Figures 2 to 3.

[0036]

Table 2

[0037] AA6066 alloy showed the lowest extrusion speed, followed by AA6056 alloy. AA6111 alloy had the highest maximum ram speed and was the most extrudable among the three alloys. AA6111, which is widely used as an automotive seat alloy, resulted in a fully recrystallized grain structure and did not meet the minimum yield strength target of 350 MPa. Both AA6056 alloy and AA6066 alloy showed yield strengths exceeding the target of 350 MPa, mainly with fibrous or non-recrystallized grain structures. However, the high strength of these alloys did not lead to an increase in energy absorption, and both AA6056 and AA6066 had low results in the crushing test. In particular, AA6066 alloy had early crack initiation and a small fracture strain in the crushing test.

[0038] Example 2 The alloys listed in Table 3 were directly chill cast as ingots with a diameter of 101.6 mm, cut into billet lengths of 400 mm, and a 5% Ti-1%B grain refiner was added before casting to ensure a fine casting grain size.

[0039]

Table 3

[0040] The billets were homogenized at 550 °C for 2 hours and then cooled at 400 °C / hour after homogenization. These billets were extruded into a hollow profile of 40×30×2 mm using a billet temperature of 500 °C and a ram speed of 5 mm / s. The extrudate was quenched in water at a rate of approximately 1000 °C / second using a standing wave water quenching unit located approximately 2.5 m from the extrusion die. After the extrudate was floor-aged at room temperature for 24 hours, it was artificially aged at 175 °C for 8 hours. Tensile and crushing tests were conducted, the extrusion hydraulic pressure was monitored, and the maximum (breakthrough) pressure value and the value at 50% of the ram stroke were extracted. The percentage difference in the breakthrough pressure compared with Alloy A (ΔP) was calculated to obtain an index of relative extrudability. The increase in yield strength per percentage increase in extrusion pressure compared with Alloy A was also calculated to evaluate the strengthening efficiency compared with the effect on extrudability. The test results are summarized in Table 4. In the table, RX indicates a fully recrystallized grain structure, and F indicates a mainly fibrous grain structure. Some of these results are also graphically shown in Figures 2 to 4.

[0041]

Table 4

[0042] Alloy A, used for comparison purposes, was based on automotive grade AA6082 and achieved good ductility and good crush ratings, but only a yield strength of 312 MPa. This alloy had Mn and Cr added, which formed submicron dispersoid particles during homogenization, resulting in a mainly fibrous / non-recrystallized grain structure after extrusion. Alloy B, with V added to Alloy A, showed similar strength and ductility, but the crush rating was slightly (one grade) improved. Alloy C, with 0.32% Cu added to Alloy A, showed a yield strength exceeding the target of 350 MPa, and the ductility measured by elongation at break and crush rating decreased slightly. Alloy D, with 0.61% Cu added to Alloy A, showed an excellent yield strength of 379 MPa, and a slightly lower elongation at break and inferior crush rating compared to Alloy C. Alloy E, with 0.30% Cu added to Alloy A but no Cr added and only 0.07% Mn added, resulted in a recrystallized grain structure. Alloy E showed only a yield strength of 346 MPa, but Alloy E also resulted in the lowest elongation at break and the highest (worst) crush rating of 9, representing complete collapse. Finally, Alloy F, similar to Alloy C but with an increased Mn content of 0.77, had a strength slightly lower than that of Alloy C and almost achieved the target of 350 MPa, but the crush rating was significantly improved.

[0043] The elongation at break and crush rating results for Examples 1 and 2 are plotted in Figure 2 as a function of yield strength. Examination of this plot reveals that alloys C and D provide a yield strength exceeding 350 MPa and reasonable ductility with respect to crush rating and elongation at break. Existing commercially available alloys AA6066 and AA6056 allow for higher strength, but this increased strength is accompanied by a significant decrease in elongation at break and crush rating compared to alloys C and D. Results for other alloy variations suggest that a mainly fibrous (non-recrystallized) grain structure is preferred, and it is undesirable for the Mn level to be reduced and Cr to be absent, as in the case of alloy E. The improved crush rating and moderately high yield strength of alloy F suggest that it may also be beneficial to increase the Mn level to about 0.8% in addition to adding Cr.

[0044] Figure 3 shows a similar plot of MCF versus yield strength for the alloys of Examples 1 and 2. Generally, MCF increases proportionally with the yield strength, but alloys E and AA6066 were exceptions as they had reduced ductility and failed early in the crushing test. Similar conclusions can be drawn from the data in Figures 2 and 3.

[0045] Figure 4 shows the results of the extrusion pressure of the breakthrough pressure (upper curve) and the pressure at the intermediate stroke (lower curve), and by plotting again against the yield strength, it shows the penalty in extrudability resulting from increasing the alloy strength. Adding additional solutes to the alloy to obtain additional strength from artificial aging is expected to increase the high-temperature flow stress and make it more difficult to extrude the alloy. Generally, the higher the extrusion pressure of the alloy, the lower the maximum extrusion speed that can be achieved for a given billet temperature. Using alloy A as the baseline, Figure 4 shows that alloy E was the only variant that showed a lower extrusion pressure than the base alloy. However, as described above, this also corresponds to significantly inferior ductility. Alloy B, including V addition, required approximately 5% higher breakthrough pressure than alloy A, with no corresponding increase in yield strength. Alloys C and D required an increase in extrusion pressure of 1.8 and 5.9%, respectively, for a useful increase in yield strength of 49 and 67 MPa compared to alloy A. Alloy F required an increase in breakthrough pressure of 6.9% for an increase in yield strength of 36 MPa compared to alloy A. Comparing the increase in yield strength per percentage increase in the breakthrough pressure value in Table 4, it is clear that alloys C and D with approximately 0.3 and 0.6 of Cu added are the most efficient in achieving the target strength level while minimizing the decrease in extrudability.

[0046] Example 3 The alloy compositions G and H shown in Table 5 were directly chill cast as 228 mm diameter ingots, cut into billets, homogenized at 560 °C for 2 hours, and cooled at 450 °C / hour after homogenization. Five billets of each alloy were extruded on a commercial extrusion press into a 2-cavity bumper profile having a wall thickness varying between 2.6 and 3.6 mm. A billet preheat temperature of 500 °C was used at a ram speed of 3 mm / s. The profiles were spray water quenched and artificially aged at 175 °C for 8 hours. Alloys G and H contained similar Cu, Mn, and Cr contents as those of alloy D from Example 2, but the Mg and Si contents of these alloys were increased relative to alloy D. Tensile tests were carried out at the top and bottom of the profiles. The results are shown in Table 5.

[0047]

Table 5

[0048] When the grain structure was checked by optical metallography, all the extrusions mainly had a fibrous / non-recrystallized grain structure. The strength of both alloys G and H varied between the top and bottom positions, which is most likely due to the variation in the quenching rate related to the spray quenching setup. Both alloys achieved a yield strength of 360 MPa or more at the lower position with a low quenching rate and a yield strength close to or above 380 MPa at the upper position with a high quenching rate.

[0049] Example 4 The alloy I shown in Table 6 was directly chill cast as 101.6 mm ingots, cut into billets. The billets were homogenized at 560 °C for 2 hours, cooled at 450 °C / hour after homogenization, and then extruded into 50×2.5 mm strips using a billet temperature of 500 °C and a ram speed of 5 mm / s. The extrusions were water quenched at a rate of 1000 °C / second at the press exit and then artificially aged at 175 °C for 8 hours. After this treatment, alloy I achieved a yield strength of 391 MPa, a maximum tensile strength of 419 MPa, and an elongation of 12.7% in the tensile test.

[0050]

Table 6

[0051] Alloy J shown in Table 7 was directly chill cast as a 254 mm diameter billet, homogenized at 560 °C for 3 hours, and cooled at 400 °C / hour after homogenization.

[0052]

Table 7

[0053] This billet was extruded into a bumper profile having an extrusion ratio of 50.1 and a wall thickness of 2.5 - 5 mm using a commercial press at a billet temperature of 490 °C and an exit speed of 8 m / min. The profile was spray quenched at the press exit. After artificial aging at 175 °C for 8 hours, Alloy J achieved a yield strength of 395 MPa, a maximum tensile strength of 421.9 MPa, and an elongation of 10.4%.

[0054] Example 5 The alloy compositions listed in Table 8 were direct chill cast as 101.6 mm ingots and cut into 200 mm billet lengths. The billets were grain refined using a 5% Ti-1% B grain refiner added prior to casting. The billets were homogenized at 560 °C for 3 hours and then cooled at 400 °C / hour. However, since Alloy M has a low equilibrium solid fraction, it was homogenized at 545 °C for 3 hours to avoid melting and then cooled at 400 °C / hour. Groups of six billets of each alloy were extruded into a 3×42 mm outer shape with sharp corners using a billet temperature of 480 °C. The ram speed of each group was incrementally increased from 4 mm / s to 9 mm / s on a continuous billet until velocity cracking was observed at the corners, and based on this observation, the maximum extrusion speed without fracture (Vt) was established. The extrusions were water quenched at the press exit using a standing wave water quenching unit that gave a quenching rate of approximately 1000 °C / second. The maximum breakthrough pressure was recorded during extrusion. The extrusions were then aged at 175 °C for 8 hours and tensile tests were performed. Table 8 shows the results for each alloy regarding the tear speed (Vt), yield strength (YS), maximum tensile strength (UTS), and breakthrough pressure (Pmax). Figure 5 shows the Mg and Si compositions of Alloys G to M in Table 6 compared to the Mg / Si plots I to IV and I to IV’ shown in Figure 1 and the ranges of 0.60 to 0.80 wt% Mg and 0.85 to 1.10 wt% Si described herein. As shown in Figure 5, Alloys G, H, I, and J are within these ranges, and Alloys K, L, and M are outside these ranges.

[0055]

Table 8

[0056] Alloys G, H, I, and J all achieved a yield strength level exceeding 370 MPa, met the target strength of 350 MPa, and exceeded it comfortably. Alloys H and J had high Si contents, and these alloys showed significantly lower tearing rates than alloys G and I. Alloy I achieved the best combination of high strength and high extrusion speed among the alloys tested in this example. Table 8 shows the increase or decrease in % breakthrough pressure (ΔP%) compared to Alloy I. For alloys J and M, extrusion pressure values are not shown because these alloys could not be extruded at the same speed as the other alloys.

[0057] Alloys K, L, and M have compositions outside of Mg / Si plots I - IV shown in Figure 1, and all of these alloys showed lower yield strengths than alloys G, H, I, and J that fall within Mg / Si plots I - IV. Alloy K has a lower Si content with a composition such that it is outside of Mg / Si plots I - IV shown in Figure 1, and this alloy achieved a yield strength of only 352 MPa. The yield strength of Alloy K does not sufficiently exceed the target strength of 350 MPa, indicating that excellent results can be obtained by setting the Si content to 0.72 wt% or more to stably meet the target strength in mass - produced alloys. Alloy M has the highest silicon content and has a composition such that it is outside of Mg / Si plots I - IV shown in Figure 1. Alloy M showed the lowest tearing rate, indicating that Alloy M is inferior in extrusion. Also, Alloy M only exceeds the target strength of 350 MPa by 10 MPa, and the yield strength of Alloy M does not sufficiently exceed the target strength of 350 MPa, and thus the target strength cannot be stably met in mass - produced alloys. The loss of extrudability and strength in Alloy M compared to alloys G, H, I, and J indicates that a silicon content lower than 1.14 wt% achieves excellent results. Alloy L has a high Mg content and has a composition such that it is outside of Mg / Si plots I - IV shown in Figure 1. Alloy L generally showed acceptable strength and tearing rate. However, Alloy L still has a lower strength than alloys G, H, I, and J, and furthermore, it has a higher extrusion pressure (and thus inferior extrudability) compared to alloys G, H, and I. Therefore, under commercial extrusion conditions, it is necessary to raise the billet temperature to lower the extrusion pressure, and the extrusion speed of Alloy L may be further limited. Thus, Alloy L represents a combination of Mg and Si that is inferior in the combination of strength and extrudability compared to alloys (e.g., alloys G, H, and I) that fall within Mg / Si plots I - IV shown in Figure 1.

[0058] Based on the strengths and extrudabilities of alloys G, H, I, and J in this test, the ranges of Mg and Si in Mg / Si plots I - IV shown in Figure 1, as well as the ranges of 0.60 - 0.80 wt% Mg and 0.85 - 1.10 wt% Si described herein, have been demonstrated to be able to provide a yield strength level comfortably exceeding the target of 350 MPa along with good extrudability. These test results also prove that lower silicon contents do not provide sufficient strength, and higher silicon contents provide inferior strength and inferior extrudability. From these test results, it was also confirmed that as the Mg content increases, the extrusion pressure rises, the extrudability deteriorates, and the strength is also slightly inferior. The test results further prove that the use of Mg and Si in the range of 0.70 - 0.80 wt% Mg and 0.85 - 0.95 wt% Si achieves a particularly advantageous combination of strength and extrudability.

[0059] In this specification, several alternative embodiments and examples are described and illustrated. Those skilled in the art will understand the features of the individual embodiments, as well as the possible combinations and variations of the components. Those skilled in the art will further understand that any of the embodiments can be provided in any combination with other embodiments disclosed herein. It is understood that the present invention can be embodied in other specific forms without departing from its spirit or central features. Therefore, the examples and embodiments of the present invention are considered to be illustrative and not restrictive in all respects, and the present invention is not limited to the details given herein. Thus, while specific embodiments have been illustrated and described, numerous modifications can be envisioned without departing significantly from the spirit of the present invention, and the scope of protection is limited only by the appended claims.

Claims

1. A final extrusion profile comprised of an aluminum alloy, comprising Si and Mg in weight percent in amounts within a quadrilateral defined by the following coordinates on a Mg / Si plot: I 1.15 Si, 0.70 Mg II 0.95 Si, 0.55 Mg III 0.75 Si, 0.65 Mg IV 0.95 Si, 0.85 Mg wherein the alloy further comprises, in weight percent: Mn 0.40-0.80 Fe maximum 0.25 Cr 0.05~0.18 Cu 0.30-0.90 Ti max 0.05 Zr maximum 0.03 Zn maximum 0.03 B Maximum 0.01 the balance being aluminum and incidental impurities, the incidental impurities each in an amount of up to 0.05% by weight and up to 0.15% by weight in total; A final extrusion profile having a yield strength of at least 350 MPa and a tensile elongation of at least 8%.

2. 2. The final extrusion profile of claim 1, wherein Mg and Si are present in a Mg / Si ratio of 0.88 or less.

3. 2. The final extrusion profile of claim 1, wherein Mg and Si are present in a Mg / Si ratio of at least 0.

69.

4. 2. The final extrusion profile of claim 1, wherein Mg and Si are present in a Mg / Si ratio of 0.69 to 0.

88.

5. 2. The final extrusion profile of claim 1, wherein the alloy includes excess Mg defined by the formula: Excess Mg = Mg - (Si - (Mn + Fe + Cr) / 3) / 1.16 (all values ​​in weight %)

6. 6. The final extrusion profile of claim 5, wherein said alloy comprises up to 0.40 wt.% of said excess Mg.

7. 10. The final extrusion profile of claim 1, wherein the alloy has a microstructure that is at least 50% or more non-recrystallized.

8. the amounts of Si and Mg, in weight percent, fall within a quadrilateral defined by the following coordinates on the Mg / Si plot: I 1.15 Si, 0.70 Mg II 0.95 Si, 0.55 Mg III' 0.80 Si, 0.65 Mg IV' 0.95 Si, 0.80 Mg In weight percent, Mg 0.60-0.80 Si 0.85~1.10 Mn 0.40-0.80 Fe maximum 0.25 Cr 0.05~0.18 Cu 0.30-0.90 Ti max 0.05 Zr maximum 0.03 Zn maximum 0.03 B Maximum 0.01 the remainder being aluminum and incidental impurities, each of which may be up to 0.05 and the total of which may be up to 0.15; An aluminum alloy having a yield strength of at least 350 MPa and a tensile elongation of at least 8%.

9. the amounts of Si and Mg, in weight percent, fall within a quadrilateral defined by the following coordinates on the Mg / Si plot: I 1.15 Si, 0.70 Mg II 0.95 Si, 0.55 Mg III' 0.80 Si, 0.65 Mg IV' 0.95 Si, 0.80 Mg In weight percent, Mg 0.60-0.80 Si 0.85~1.10 Mn 0.40-0.80 Fe maximum 0.25 Cr 0.05~0.18 Cu 0.30-0.90 Ti max 0.05 Zr maximum 0.03 Zn maximum 0.03 B Maximum 0.01 the remainder being aluminum and incidental impurities, each of which may be up to 0.05 and the total of which may be up to 0.15; An aluminum alloy having a yield strength of at least 370 MPa.

10. 2. The final extrusion profile of claim 1, wherein the alloy comprises Mg in an amount of 0.60-0.80 wt.% and Si in an amount of 0.85-1.10 wt.%.

11. 2. The final extrusion profile of claim 1, wherein the alloy comprises Mg in an amount of 0.70-0.80 wt.% and Si in an amount of 0.85-0.95 wt.%.

12. 2. The final extrusion profile of claim 1, wherein the amounts of Si and Mg, in weight percent, are within a quadrilateral defined by the following coordinates on the Mg / Si plot: I 1.15 Si, 0.70 Mg II 0.95 Si, 0.55 Mg III' 0.80 Si, 0.65 Mg IV' 0.95 Si, 0.80 Mg

13. 1. A final extrusion profile comprised of an aluminum alloy comprising, in weight percent: Mg 0.60-0.80 Si 0.85~1.10 Mn 0.40-0.80 Fe maximum 0.25 Cr 0.05~0.18 Cu 0.30-0.90 Ti max 0.05 Zr maximum 0.03 Zn maximum 0.03 B Maximum 0.01 the remainder being aluminum and incidental impurities, each of which may be up to 0.05, with the total amount of the incidental impurities being up to 0.15; A final extrusion profile having a yield strength of at least 350 MPa and a tensile elongation of at least 8%.

14. 14. The final extrusion profile of claim 13, wherein the Mg and Si are present in a Mg / Si ratio of 0.88 or less.

15. 14. Final extrusion profile according to claim 13, wherein the Mg and Si are present in a Mg / Si ratio of at least 0.

69.

16. Final extrusion profile according to claim 13, wherein said Mg and Si are present in a Mg / Si ratio of 0.69 to 0.

88.

17. 14. The final extrusion profile of claim 13, wherein the alloy comprises excess Mg defined by the formula: Excess Mg = Mg - (Si - (Mn + Fe + Cr) / 3) / 1.16 (all values ​​in weight %)

18. 18. The final extrusion profile of claim 17, wherein said alloy comprises up to 0.40 wt.% of said excess Mg.

19. 14. The final extrusion profile of claim 13, wherein the alloy has a microstructure that is at least 50% or more non-recrystallized.

20. An aluminum alloy having, in weight percent: Mg 0.60-0.80 Si 0.85~1.10 Mn 0.40-0.80 Fe maximum 0.25 Cr 0.05~0.18 Cu 0.30-0.90 Ti max 0.05 Zr maximum 0.03 Zn maximum 0.03 B Maximum 0.01 the remainder being aluminum and incidental impurities, each of which may be up to 0.05 and the total of which may be up to 0.15; An aluminum alloy having a yield strength of at least 350 MPa and a tensile elongation of at least 8%.

21. An aluminum alloy having, in weight percent: Mg 0.60-0.80 Si 0.85~1.10 Mn 0.40-0.80 Fe maximum 0.25 Cr 0.05~0.18 Cu 0.30-0.90 Ti max 0.05 Zr maximum 0.03 Zn maximum 0.03 B Maximum 0.01 the remainder being aluminum and incidental impurities, each of which may be up to 0.05 and the total of which may be up to 0.15; 1. An aluminum alloy, wherein the alloy has a yield strength of at least 370 MPa.

22. 14. The final extrusion profile of claim 13, wherein the alloy comprises Mg in an amount of 0.70-0.80 wt.% and Si in an amount of 0.85-0.95 wt.%.

23. 1. Producing a billet of an aluminum alloy, the aluminum alloy comprising: I 1.15 Si, 0.70 Mg II 0.95 Si, 0.55 Mg III 0.75 Si, 0.65 Mg IV 0.95 Si, 0.85 Mg wherein the alloy further comprises, in weight percent: Mn 0.40-0.80 Fe maximum 0.25 Cr 0.05~0.18 Cu 0.30-0.90 Ti max 0.05 Zr maximum 0.03 Zn maximum 0.03 B Maximum 0.01 producing a billet of an aluminum alloy, the balance being aluminum and unavoidable impurities in an amount of up to 0.05% by weight each and up to 0.15% by weight total; homogenizing the billet at a temperature of 540-580° C. for 2-10 hours; extruding the billet after homogenization to form an extruded product; A method comprising:

24. 1. Producing a billet of an aluminum alloy, the aluminum alloy comprising: Mg 0.60-0.80 Si 0.85~1.10 Mn 0.40-0.80 Fe maximum 0.25 Cr 0.05~0.18 Cu 0.30-0.90 Ti max 0.05 Zr maximum 0.03 Zn maximum 0.03 B Maximum 0.01 producing a billet of an aluminum alloy, the balance being aluminum and unavoidable impurities in an amount of up to 0.05% by weight each and up to 0.15% by weight total; homogenizing the billet at a temperature of 540-580° C. for 2-10 hours; extruding the billet after homogenization to form an extruded product; A method comprising:

25. The final extrusion profile of claim 1 or claim 13, wherein the minimum wall thickness of the final extrusion profile is 2 mm or more and 5 mm or less.

26. 14. The final extrusion profile of claim 1 or claim 13, wherein the final extrusion profile is a hollow member.

27. 14. The final extrusion profile of claim 1 or claim 13, wherein the final extrusion profile has at least one concave surface and / or at least one internal cavity.

28. 22. An extruded product at least partially formed from an aluminium alloy according to claim 8, claim 9, claim 20 or claim 21.

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