6xxx aluminum alloy suitable for wide thin-walled aluminum profile extrusion and preparation method thereof

Abstract

The application belongs to the alloy field, and particularly discloses a 6XXX aluminum alloy suitable for wide-thin-wall aluminum profile extrusion and a preparation method thereof. The aluminum alloy is composed of the following components in mass percentage: Si 0.65-0.85%, Mg 0.25-0.38%, Fe≤0.15%, Zr 0.10-0.15%, Sr 0.004-0.01%, RE 0.01-0.03%, Ti≤0.01%, inevitable impurity elements≤0.20%, and the balance of Al; and RE is at least one selected from La and Ce. The aluminum alloy has high mechanical properties and excellent extrudability, the tensile strength is 250-270 MPa, the yield strength is 210-230 MPa, the elongation is 12-16%, the maximum extrusion pressure is 10-20 kN, the maximum extrusion speed is 7.5-8.5 mm / s, and the aluminum alloy can be used for preparing wide-thin-wall products.

Description

Technical Field

[0001] This invention belongs to the field of alloys, specifically relating to a 6XXX aluminum alloy suitable for wide-width thin-walled aluminum profile extrusion and its preparation method. Background Technology

[0002] 6XXX aluminum alloys possess excellent thermal and electrical conductivity, corrosion resistance, and processability, making them widely used in the automotive, communications, electronics, and wire industries. In recent years, with the rise of new energy vehicles and energy storage industries, the demand for wide, thin-walled aluminum profiles has been increasing. The required profile width has increased from the traditional 500mm to over 800mm, with an average thickness not exceeding 3mm. This not only places stricter demands on extrusion equipment but also imposes higher requirements on the extrudability of aluminum alloy materials.

[0003] Extrudability refers to the ability of an alloy to undergo plastic deformation without defects during extrusion processing. The main factors affecting the extrudability of aluminum alloys include alloy composition, microstructure, and die. In the alloy composition, higher contents of strengthening elements such as Cu, Zn, Mg, and Si increase material strength but decrease plasticity, making extrusion more difficult. Transition elements, such as Fe, Ti, Mn, and Cr, readily form large, hard, and brittle intermetallic compounds with Al and Si, hindering material flow and increasing hot extrusion resistance. Furthermore, finer and more uniform grain size allows for more uniform extrusion deformation. Traditional 6063 aluminum alloy has good extrusion performance, but its low Fe, Mn, and Cr content makes it prone to coarsening during hot extrusion, resulting in poor mechanical properties of the profile. Alloys such as 6061 and 6082 contain higher contents of Mg, Mn, and Cr, affecting their extrudability and preventing the extrusion of wide, thin-walled profiles. Summary of the Invention

[0004] In order to overcome at least one of the technical problems existing in the prior art, one of the objectives of the present invention is to provide an aluminum alloy with a uniform and fine microstructure and high extrudability.

[0005] The second objective of this invention is to provide a method for preparing aluminum alloys.

[0006] A third objective of this invention is to provide applications of the aforementioned aluminum alloys in the automotive, communications, electronics, or wire industries.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] The first aspect of the present invention provides an aluminum alloy composed of the following components in weight percentages: Si 0.65–0.85%, Mg 0.25–0.38%, Fe ≤0.15%, Zr 0.10–0.15%, Sr 0.004–0.01%, RE 0.01–0.03%, Ti ≤0.01%, unavoidable impurity elements ≤0.20%, and the balance being Al; wherein the RE is selected from at least one of La and Ce.

[0009] In some embodiments of the present invention, the mass ratio of Mg to Si is (0.29–0.59):1. The present invention employs a method of Si excess in the design of Mg and Si elements, that is, the Mg / Si mass ratio is much lower than 1.73, only 0.29–0.59, which significantly reduces the solid solubility of Mg and reduces its solid solution strengthening effect.

[0010] In some embodiments of the present invention, the unavoidable impurity element includes at least one of copper and zinc.

[0011] This invention reduces the content of strengthening elements (such as Mg) and impurity elements through compositional optimization design, thereby lowering the resistance to hot extrusion. Firstly, the Mg content is significantly reduced, controlled within the range of 0.25–0.38%. Secondly, the iron-rich phase is refined by introducing Sr and RE through composite modification, improving the alloy's electrical and thermal conductivity. An Al-Sr-RE composite modifier is used to modify the iron-rich phase, improving the size, morphology, and distribution of the second phase. The principle is that Sr and RE are both highly reactive elements, and in Al-Sr-RE master alloys, they are mainly represented by Al₄(SrRE) and Al₂O₃. 11 The Al-Sr-RE master alloy exists in the form of a (SrRE)3 phase. When added to the molten aluminum, Sr and RE atomic clusters are formed, adsorbed on the surface of the iron-rich phase, inhibiting its nucleation and growth, promoting its transformation from long needle-like to short rod-like shapes, and improving the uniformity of its distribution. Furthermore, this invention also inhibits abnormal grain growth during hot extrusion through Zr alloying. By adding a high Zr content and utilizing the temperature-dependent solubility of Zr in Al alloys, combined with a low-temperature homogenization process, high-density, small-sized Al3Zr is precipitated, suppressing grain coarsening.

[0012] In some embodiments of the present invention, the mass percentage of Si is selected from any value or a range formed by any two of the following: 0.65%, 0.66%, 0.67%, 0.68%, 0.69%, 0.70%, 0.71%, 0.72%, 0.73%, 0.74%, 0.75%, 0.76%, 0.77%, 0.78%, 0.79%, 0.80%, 0.81%, 0.82%, 0.83%, 0.84%, and 0.85%.

[0013] In some embodiments of the present invention, the mass percentage of Mg is selected from any value of 0.25%, 0.26%, 0.27%, 0.28%, 0.29%, 0.30%, 0.31%, 0.32%, 0.33%, 0.34%, 0.35%, 0.36%, 0.37%, 0.38%, or a range formed by any two of these values.

[0014] In some embodiments of the present invention, the mass percentage of Fe is 0 to 0.15%; in some embodiments of the present invention, the mass percentage of Fe can be selected from any value of 0%, 0.01%, 0.02%, 0.04%, 0.06%, 0.08%, 0.10%, 0.12%, 0.14%, 0.15% or a range formed by any two of these values.

[0015] In some embodiments of the present invention, the mass percentage of Zr is selected from any value of 0.10%, 0.11%, 0.12%, 0.13%, 0.14%, 0.15%, or a range formed by any two of these values.

[0016] In some embodiments of the present invention, the mass percentage of Sr is selected from any value of 0.004%, 0.005%, 0.006%, 0.007%, 0.008%, 0.009%, 0.01%, or a range formed by any two of these values.

[0017] In some embodiments of the present invention, the mass percentage of the RE is selected from any value of 0.01%, 0.015%, 0.02%, 0.025%, 0.03%, or a range formed by any two of these values.

[0018] In some embodiments of the present invention, the mass percentage of Ti is 0 to 0.01%; in some embodiments of the present invention, the mass percentage of Ti is selected from any value of 0%, 0.001%, 0.002%, 0.003%, 0.004%, 0.005%, 0.006%, 0.007%, 0.008%, 0.009%, 0.01%, or a range formed by any two of these values.

[0019] In some embodiments of the present invention, the content of a single impurity element in the aluminum alloy is ≤0.05%. By controlling the content of a single impurity element to below 0.05%, the present invention can significantly reduce hot extrusion resistance, reduce the maximum extrusion pressure during hot extrusion, and increase the maximum extrusion speed, thereby improving the extrudability of the aluminum alloy.

[0020] In some embodiments of the present invention, the Sr and RE are added in the form of Al-Sr-RE. Al-Sr-RE is used as a composite modifier in the present invention.

[0021] In some embodiments of the present invention, the Si is added in the form of fast-melting silicon or Al-Si master alloy.

[0022] In some embodiments of the present invention, the Zr is added as an Al-Zr master alloy.

[0023] The second aspect of the present invention provides a method for preparing the aluminum alloy described in the first aspect of the present invention, comprising the following steps:

[0024] Raw materials including Al, Mg, Si, and Zr sources are melted and refined, and then mixed with an Al-Sr-RE master alloy for modification to obtain an aluminum alloy melt.

[0025] The aluminum alloy melt was cast into aluminum alloy rods using electromagnetic casting.

[0026] The aluminum alloy casting rod is subjected to a first homogenization treatment, then a second homogenization treatment, and then hot extrusion to obtain an aluminum alloy profile.

[0027] The aluminum alloy profile is obtained by aging treatment.

[0028] This invention employs electromagnetic casting to cast molten aluminum alloy, which refines grain size, promotes uniform distribution of solute atoms and temperature, and simultaneously breaks up dendrites. This allows the preparation method to omit the grain refiner Al-Ti-B, avoiding the adverse effects of TiB2 on extrusion performance. Furthermore, Zr in the alloy significantly reduces the grain refining effect of Al-Ti-B, resulting in coarse as-cast grains. This invention also utilizes a two-stage homogenization process to improve high-temperature dispersion and the morphology of the iron-rich phase.

[0029] In some embodiments of the present invention, the refining process is ≥1 time; in some embodiments of the present invention, the refining process is 1 to 3 times.

[0030] In some embodiments of the present invention, the amount of refining agent added during each refining process is 0.15 to 0.25% of the melt mass.

[0031] In some embodiments of the present invention, the refining step specifically involves: adding the refining agent to the melt using an inert gas as a carrier gas, mixing and letting it stand for 15 to 30 minutes, and then removing the slag.

[0032] In some embodiments of the present invention, the inert gas is selected from at least one of nitrogen, argon, and helium.

[0033] In some embodiments of the present invention, the width of the aluminum alloy profile is ≥800mm and the average thickness of the aluminum alloy profile is ≤3mm.

[0034] In some embodiments of the present invention, the preparation method further includes a step of adding a covering agent, wherein the step of adding the covering agent is located after the melting step and / or before the electromagnetic casting step.

[0035] In some embodiments of the present invention, the preparation method further includes the steps of degassing and filtering the aluminum alloy melt, which are performed before the electromagnetic casting step.

[0036] In some embodiments of the present invention, the steps of performing a first homogenization treatment on the aluminum alloy profile, followed by a second homogenization treatment, and then hot extrusion and aging treatment in sequence are specifically as follows: the aluminum alloy profile is subjected to a first homogenization treatment at 350-450°C for 2-4 hours, then heated to 560-580°C for a second homogenization treatment for 4-8 hours, cooled, then hot extruded, and then aged to obtain the aluminum alloy.

[0037] In some embodiments of the present invention, the cooling step is performed using at least one of air cooling and water cooling.

[0038] In some embodiments of the present invention, the Al source is industrial pure aluminum.

[0039] In some embodiments of the present invention, the Mg source is industrial pure magnesium.

[0040] In some embodiments of the present invention, the Si source includes at least one of fast-melting silicon or Al-Si master alloy.

[0041] In some embodiments of the present invention, the Zr source is an Al-Zr master alloy.

[0042] In some embodiments of the present invention, the temperature of the first homogenization treatment is 350–450°C; in some embodiments of the present invention, the temperature of the first homogenization treatment is any value or a range formed by any two of 350°C, 360°C, 370°C, 380°C, 390°C, 400°C, 410°C, 420°C, 430°C, 440°C, and 450°C.

[0043] In some embodiments of the present invention, the time for the first homogenization process is 2 to 4 hours; in some embodiments of the present invention, the time for the first homogenization process is any value of 2 hours, 2.5 hours, 3 hours, 3.5 hours, 4 hours, or a range formed by any two of them.

[0044] In some embodiments of the present invention, the temperature of the second homogenization treatment is 560–580°C; in some embodiments of the present invention, the temperature of the second homogenization treatment is any value or a range formed by any two of 560°C, 562°C, 564°C, 566°C, 568°C, 570°C, 572°C, 574°C, 576°C, 578°C, and 580°C.

[0045] In some embodiments of the present invention, the time for the second homogenization process is 4 to 8 hours; in some embodiments of the present invention, the time for the second homogenization process is any value of 4 hours, 4.5 hours, 5 hours, 5.5 hours, 6 hours, 6.5 hours, 7 hours, 7.5 hours, 8 hours, or a range formed by any two of these values.

[0046] This invention employs a first homogenization treatment at low temperature to facilitate the precipitation of high-density, small-sized Al3Zr, thereby suppressing the growth of deformed grains. Then, a second homogenization treatment at high temperature promotes the dissolution and melting of β-Al5FeSi.

[0047] In some embodiments of the present invention, the aging temperature is 160–200°C; in other embodiments, the aging temperature is any value of 160°C, 170°C, 180°C, 190°C, or 200°C, or a range formed by any two of these values. The aging treatment in this invention can control the morphology of the second phase, thereby improving the mechanical properties and extrudability of the resulting aluminum alloy.

[0048] In some embodiments of the present invention, the effective period is 2 to 10 hours; in some embodiments of the present invention, the effective period is any value of 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, 10 hours or a range formed by any two of them.

[0049] A third aspect of the invention provides the application of the aluminum alloy described in the first aspect of the invention in the automotive, communications, electronics or wire industries.

[0050] The beneficial effects of this invention are: the aluminum alloy in this invention has high mechanical properties and excellent extrudability, specifically: the tensile strength of the aluminum alloy is 250-270 MPa, the yield strength is 210-230 MPa, the elongation is 12-16%, the maximum extrusion pressure is 10-20 kN, and the maximum extrusion speed is 7.5-8.5 mm / s, which can be used to prepare wide-width thin-walled products. Detailed Implementation

[0051] The following examples provide a more detailed description of the specific implementation of the present invention, but the implementation and protection of the present invention are not limited thereto. It should be noted that any processes not specifically described below are methods that can be implemented or understood by those skilled in the art by referring to existing technology. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0052] Example 1

[0053] This example provides a 6XXX aluminum alloy suitable for extruding wide, thin-walled aluminum profiles, which is composed of the following alloy composition by mass percentage: Si 0.65%, Mg 0.28%, Fe 0.10%, Zr 0.12%, Sr 0.006%, Ce 0.018%, Ti 0.001%, total unavoidable impurity elements ≤0.20%, individual impurity element content ≤0.05%, and the balance being Al.

[0054] The 6XXX aluminum alloy in this example is prepared using a method that includes the following steps:

[0055] Step 1: Batching. Batching is carried out according to the alloy composition, where Al is industrial pure aluminum, Mg is industrial pure magnesium, Si is fast-melting silicon, Zr is an Al-Zr master alloy, and Sr and Ce are added in the form of Al-6Sr-9Ce composite modifiers.

[0056] Step 2: Adding materials and smelting. Industrial pure aluminum and quick-melting silicon are added to the smelting furnace, and a layer of commercially available aluminum alloy covering agent is sprinkled on the surface of the melt; after it is completely melted, industrial pure magnesium alloy and Al-Zr master alloy are added.

[0057] Step 3: First refining. Use high-purity argon gas (purity ≥99.9%) to evenly blow 0.15% of commercially available refining agent by mass into the melt, let it stand for 30 minutes, and then remove the slag.

[0058] Step 4: Composition Adjustment. Take samples to test the composition of the melt and adjust the Si and Mg contents to within the acceptable range.

[0059] Step 5: Second Refining and Modification Treatment. The melt undergoes a second refining process, identical to the first, with the refining agent accounting for 0.10% of the melt mass. Subsequently, 0.2% of the melt mass of the Al-6Sr-9Ce composite modifier is added, and the electromagnetic stirring device is activated to promote homogenization of the melt composition. The Al-6Sr-9Ce composite modifier contains 6% Sr by mass, 9% Ce by mass, and the balance is Al.

[0060] Step 6: Electromagnetic casting. After the melt has stood for 30 minutes, slag is removed, and a covering agent is then applied to the surface of the molten aluminum. The molten aluminum alloy is then introduced into a flow channel, passing through a degassing box and a ceramic filter plate. The aluminum alloy is then cast in a semi-continuous casting system equipped with electromagnetic casting technology to produce aluminum alloy round bars with a diameter of 486 mm.

[0061] Step 6: Homogenization. The aluminum rod is heated and subjected to a two-stage homogenization process: 350℃, held for 4 hours, then heated to 580℃ and held for 4 hours. After the holding period, forced cooling is performed using strong airflow and water mist.

[0062] Step 7: Hot extrusion. Cut the aluminum alloy round bar into sections, preheat it, and then perform hot extrusion. Use strong air cooling to quench the profiles online.

[0063] Step 8: Artificial aging. Heat the profile to 160℃ and hold for 10 hours; after cooling to room temperature in the furnace, the 6XXX aluminum alloy profile in this example is obtained.

[0064] In this example, the 6XXX aluminum alloy profile has a width of 800mm and an average thickness of 2.5mm, making it a wide-width, thin-walled aluminum profile.

[0065] Example 2

[0066] This example provides a 6XXX aluminum alloy suitable for extruding wide, thin-walled aluminum profiles, which is composed of the following alloy composition by mass percentage: Si 0.85%, Mg 0.35%, Fe 0.08%, Zr 0.10%, Sr 0.006%, La 0.012%, Ti 0.005%, total unavoidable impurity elements 0.19%, the content of a single impurity element not exceeding 0.05%, and the balance being Al.

[0067] The 6XXX aluminum alloy in this example is prepared using a method that includes the following steps:

[0068] Step 1: Batching. Batching is carried out according to the alloy composition, where Al is industrial pure aluminum, Mg is industrial pure magnesium, Si is Al-Si master alloy, Zr is Al-Zr master alloy, and Sr and La are added in the form of Al-8Sr-12La composite modifier.

[0069] Step 2: Charging and Smelting. Industrial pure aluminum and Al-Si master alloy are added to the smelting furnace, and a layer of commercially available covering agent is sprinkled on the surface of the furnace charge; after complete melting, industrial pure magnesium alloy and Al-Zr master alloy are added.

[0070] Step 3: First refining. Use high-purity nitrogen (purity ≥99.9%) to evenly blow 0.20% of commercially available refining agent, which accounts for 0.20% of the total mass of the melt, into the melt. After standing for 15-30 minutes, remove the slag.

[0071] Step 4: Composition Adjustment. Take samples to test the composition of the melt and adjust the Si and Mg contents to within the acceptable range.

[0072] Step 5: Second Refining and Modification Treatment. The melt undergoes a second refining process, identical to the first, with the refining agent accounting for 0.15% of the total melt mass. Subsequently, 0.1% of the total melt mass of Al-8Sr-12La composite modifier is added, and the electromagnetic stirring device is activated to promote homogenization of the melt composition. In the Al-8Sr-12La composite modifier, Sr accounts for 8% by mass, La accounts for 12% by mass, and Al is the balance.

[0073] Step 6: Electromagnetic casting. After the melt has settled for 40 minutes, slag is removed, and then a commercially available covering agent is sprinkled on the surface of the aluminum melt. The aluminum alloy melt is then introduced into a flow channel, passing through a degassing box and a ceramic filter plate. It is then cast in a semi-continuous casting system equipped with electromagnetic casting technology to produce aluminum alloy round bars with a diameter of 675 mm.

[0074] Step 6: Homogenization. The aluminum rod is heated and subjected to a two-stage homogenization process: 400℃, held for 3 hours, then heated to 570℃ and held for 6 hours. After the holding period, forced cooling is performed using strong airflow and water mist.

[0075] Step 7: Hot extrusion. Cut the aluminum alloy round bar into sections, preheat it, and then perform hot extrusion. Use strong air cooling to quench the profiles online.

[0076] Step 8: Artificial aging. Heat the profile to 180℃ and hold for 6 hours; after cooling to room temperature in the furnace, the 6XXX aluminum alloy profile in this example is obtained.

[0077] In this example, the 6XXX aluminum alloy profile has a width of 1000mm and an average thickness of 3mm, making it a wide-width, thin-walled aluminum profile.

[0078] Example 3

[0079] This example provides a 6XXX aluminum alloy suitable for extruding wide, thin-walled aluminum profiles, which is composed of the following alloy composition by mass percentage: Si 0.75%, Mg 0.35%, Fe 0.15%, Zr 0.15%, Sr 0.01%, La 0.01%, Ce 0.02%, Ti 0.002%, total unavoidable impurity elements 0.09%, the content of a single impurity element not exceeding 0.05%, and the balance being Al.

[0080] The 6XXX aluminum alloy in this example is prepared using a method that includes the following steps:

[0081] Step 1: Batching. Batching is carried out according to the alloy composition, where Al is industrial pure aluminum, Fe is an element introduced into industrial pure aluminum, Mg is industrial pure magnesium, Si is fast-melting silicon, Zr is Al-Zr master alloy, and Sr, La and Ce are added in the form of Al-6Sr-4La-8Ce composite modifier.

[0082] Step 2: Charging and Smelting. Industrial pure aluminum and quick-melting silicon are added to the smelting furnace, and a layer of commercially available covering agent is sprinkled on the surface of the furnace charge; after complete melting, industrial pure magnesium alloy and Al-Zr master alloy are added.

[0083] Step 3: First refining. Use high-purity argon gas (purity ≥99.9%) to evenly blow 0.25% of commercially available refining agent by mass into the melt, let it stand for 20 minutes, and then remove the slag.

[0084] Step 4: Composition Adjustment. Take samples to test the composition of the melt and adjust the Si and Mg contents to within the acceptable range.

[0085] Step 5: Second Refining and Modification Treatment. The melt undergoes a second refining process, which is essentially the same as the first refining. Then, 0.25% (by mass) of an Al-6Sr-4La-8Ce composite modifier is added, and the electromagnetic stirring device is activated to promote homogenization of the melt composition. In the Al-6Sr-4La-8Ce composite modifier, Sr accounts for 6% by mass, La for 4% by mass, Ce for 8% by mass, and Al is the balance.

[0086] Step 6: Electromagnetic casting. After the melt has stood for 30 minutes, slag is removed, and then a commercially available covering agent is sprinkled on the surface of the aluminum melt. The aluminum alloy melt is then introduced into a flow channel, passing through a degassing box and a ceramic filter plate. It is then cast in a semi-continuous casting system equipped with electromagnetic casting technology to produce aluminum alloy round bars with a diameter of 542 mm.

[0087] Step 6: Homogenization. The aluminum rod is heated and subjected to a two-stage homogenization process: 450℃, held for 2 hours, then heated to 560℃ and held for 8 hours. After the holding period, forced cooling is performed using strong airflow and water mist.

[0088] Step 7: Hot extrusion. Cut the aluminum alloy round bar into sections, preheat it, and then perform hot extrusion. Use strong air cooling to quench the profiles online.

[0089] Step 8: Artificial aging. Heat the profile to 200℃ and hold for 2 hours; after cooling to room temperature in the furnace, the 6XXX aluminum alloy profile in this example is obtained.

[0090] In this example, the 6XXX aluminum alloy profile has a width of 820mm and an average thickness of 2.7mm, making it a wide-width, thin-walled aluminum profile.

[0091] Example 4

[0092] This example provides a 6XXX aluminum alloy suitable for extruding wide, thin-walled aluminum profiles, which is composed of the following alloy composition by mass percentage: Si 0.70%, Mg 0.30%, Fe 0.11%, Zr 0.15%, Sr 0.008%, La 0.015%, Ce 0.01%, Ti 0.003%, unavoidable total impurity elements 0.12%, the content of a single impurity element not exceeding 0.05%, and the balance being Al.

[0093] The 6XXX aluminum alloy in this example is prepared using a method that includes the following steps:

[0094] Step 1: Batching. Batching is carried out according to the alloy composition, where Al is industrial pure aluminum, Fe is an element introduced into industrial pure aluminum, Mg is industrial pure magnesium, Si is an Al-Si master alloy, Zr is an Al-Zr master alloy, and Sr, La and Ce are added in the form of Al-4Sr-3La-2Ce composite modifier.

[0095] Step 2: Charging and Smelting. Industrial pure aluminum and Al-Si intermediate are added to the smelting furnace, and a covering agent is sprinkled on the surface of the furnace charge; after complete melting, industrial pure magnesium alloy and Al-Zr intermediate alloy are added.

[0096] Step 3: First refining. Use high-purity inert gas (purity ≥99.9%) to evenly blow 0.15-0.25% of the refining agent by mass into the melt. After standing for 15-30 minutes, remove the slag.

[0097] Step 4: Composition Adjustment. Take samples to test the composition of the melt and adjust the Si and Mg contents to within the acceptable range.

[0098] Step 5: Second Refining and Modification Treatment. The melt undergoes a second refining process, which is essentially the same as the first refining. Then, 0.5% (by mass) of an Al-Sr-3La-2Ce composite modifier is added, and the electromagnetic stirring device is activated to promote homogenization of the melt composition. In the Al-4Sr-3La-2Ce composite modifier, Sr accounts for 4% by mass, La for 3% by mass, Ce for 2% by mass, and Al is the balance.

[0099] Step 6: Electromagnetic casting. After the melt has settled for 25 minutes, slag is removed, and then a commercially available covering agent is sprinkled on the surface of the aluminum melt. The aluminum alloy melt is then introduced into a flow channel, passing through a degassing box and a ceramic filter plate. It is then cast in a semi-continuous casting system equipped with electromagnetic casting technology to produce aluminum alloy round bars with a diameter of 486 mm.

[0100] Step 6: Homogenization. The aluminum rod is heated and subjected to a two-stage homogenization process: 420℃, held for 3 hours, then heated to 565℃ and held for 6 hours. After the holding period, forced cooling is performed using strong airflow and water mist.

[0101] Step 7: Hot extrusion. Cut the aluminum alloy round bar into sections, preheat it, and then perform hot extrusion. Use strong air cooling to quench the profiles online.

[0102] Step 8: Artificial aging. Heat the profile to 170℃ and hold for 8 hours; after cooling to room temperature in the furnace, the 6XXX aluminum alloy profile in this example is obtained.

[0103] In this example, the 6XXX aluminum alloy profile has a width of 810mm and an average thickness of 2.85mm, making it a wide-width, thin-walled aluminum profile.

[0104] Comparative Example 1

[0105] Compared to Example 1, the Mg content in the 6XXX aluminum alloy in this example is increased to 0.5%.

[0106] Comparative Example 2

[0107] Compared to Example 2, the 6XXX aluminum alloy in this example uses an equal amount of Mn instead of Zr in Example 2.

[0108] Comparative Example 3

[0109] The only difference between the preparation method of the 6XXX aluminum alloy in this example and that in Example 3 is that an equal amount of Al-5Ti-B is used to replace Al-Sr-RE (i.e., Al-6Sr-4La-8Ce) in Example 3.

[0110] In Al-5Ti-B, Ti accounts for 5% of the mass, B accounts for 1% of the mass, and Al is the balance.

[0111] Comparative Example 4

[0112] The composition of the 6XXX aluminum alloy in this example is the same as that in Example 4.

[0113] The difference between the preparation method of the 6XXX aluminum alloy in this example and that in Example 4 is only that step six in this example is homogenization. The aluminum rod is heated and subjected to a single-stage homogenization treatment, specifically: holding at 565℃ for 9 hours. After the holding period, forced cooling is performed using strong air and water mist.

[0114] Performance testing:

[0115] Samples were taken from the aluminum alloy profiles prepared in Examples 1-4 and Comparative Examples 1-4, and the mechanical properties of the samples were tested. The tests were conducted according to the test methods described in GB / T 228.1-2021 "Metallic materials - Tensile testing - Part 1: Test method at room temperature" to obtain tensile strength, yield strength and elongation.

[0116] The maximum extrusion pressure and maximum extrusion speed during the seventh step of hot extrusion are recorded in the table below. The results obtained according to the above test method are shown in Table 1 below.

[0117] Table 1. Test results of mechanical properties of aluminum alloys

[0118]

[0119]

[0120] As shown in Table 1, the aluminum alloys obtained in Examples 1 to 4 of the present invention have high mechanical properties and good extrudability. Specifically, the tensile strength of the aluminum alloy is 250-270 MPa, the yield strength is 210-230 MPa, the elongation is 12-16%, the maximum extrusion pressure is 18.5-20.1 kN, and the maximum extrusion speed is 7.5-8.5 mm / s.

[0121] Compared with Examples 1-4, the increased Mg content, the use of Mn instead of Zr, the use of Al-Ti-B instead of Al-Sr-Ce, and the use of single-stage homogenization in Comparative Examples 1-4 all hindered the reduction of aluminum alloy extrusion pressure, thereby impeding the increase of extrusion speed and ultimately leading to a decrease in the plasticity of aluminum alloy profiles. For example, compared with Example 1, the increased Mg content in Comparative Example 1 increased the extrusion pressure by 9.7%, reduced the maximum extrusion speed by 30.8%, and resulted in a 31.3% decrease in the elongation of the aluminum alloy profile.

[0122] The embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention. Furthermore, the embodiments of the present invention and the features thereof can be combined with each other unless otherwise specified.

Claims

1. An aluminum alloy, characterized in that: It is composed of the following components by mass percentage: Si 0.7~0.85%, Mg 0.25~0.34%, Fe≤0.15%, Zr 0.10~0.15%, Sr 0.004~0.01%, RE 0.01~0.03%, Ti≤0.01%, unavoidable impurity elements≤0.20%, and the balance being Al; The RE is selected from at least one of La and Ce; In the aluminum alloy, the content of a single impurity element is ≤0.05%; The aluminum alloy is a wide-width, thin-walled aluminum profile; the width of the wide-width, thin-walled aluminum profile is ≥800mm; the thickness of the wide-width, thin-walled aluminum profile is ≤3mm. The aluminum alloy is prepared by a method including the following steps: Raw materials including Al, Mg, Si, and Zr sources are melted and refined, and then mixed with an Al-Sr-RE master alloy for modification to obtain an aluminum alloy melt. The aluminum alloy melt was cast into aluminum alloy rods using electromagnetic casting. The aluminum alloy casting rod is subjected to a first homogenization treatment, then a second homogenization treatment, and then hot extrusion to obtain an aluminum alloy profile. The aluminum alloy profile is subjected to aging treatment to obtain the desired product. The temperature of the first homogenization treatment is 350~450℃; the temperature of the second homogenization treatment is 560~580℃; The aging treatment temperature is 160~200℃.

2. The method for preparing the aluminum alloy according to claim 1, characterized in that: Includes the following steps: Raw materials including Al, Mg, Si, and Zr sources are melted and refined, and then mixed with an Al-Sr-RE master alloy for modification to obtain an aluminum alloy melt. The aluminum alloy melt was cast into aluminum alloy rods using electromagnetic casting. The aluminum alloy casting rod is subjected to a first homogenization treatment, then a second homogenization treatment, and then hot extrusion to obtain an aluminum alloy profile. The aluminum alloy profile is subjected to aging treatment to obtain the desired product. The temperature of the first homogenization treatment is 350~450℃; the temperature of the second homogenization treatment is 560~580℃.

3. The method for preparing the aluminum alloy according to claim 2, characterized in that: The first homogenization process takes 2-4 hours.

4. The method for preparing the aluminum alloy according to claim 2, characterized in that: The second homogenization process takes 4 to 8 hours.

5. The method for preparing the aluminum alloy according to claim 2, characterized in that: The time for the time-sensitive processing is 2 to 10 hours.

6. The method for preparing the aluminum alloy according to claim 2, characterized in that: The Zr source is an Al-Zr master alloy.

7. The method for preparing the aluminum alloy according to claim 2, characterized in that: The Si source includes at least one of fast-melting silicon or Al-Si master alloy.

8. The application of the aluminum alloy of claim 1 in the fields of automobiles, communications, electronics or wires.

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