High-strength alkali-corrosion-resistant 6000-series aluminum alloy profile, bumper and preparation method thereof

Abstract

The invention relates to the technical field of non-ferrous metal composite materials, in particular to a high-strength alkali-corrosion-resistant 6000-series aluminum alloy profile, a bumper and a preparation method of the high-strength alkali-corrosion-resistant 6000-series aluminum alloy profile and the bumper. Wt.% of Mg: 0.7 to 1.1 wt.%; wt.% of Cu: 0.1 to 0.8 wt.%; wt.% of Mn: 0.3 to 0.9 wt.%; 0 to 0.5 wt.% of Fe; wt.% of Sc: 0.1 to 0.2 wt.%; %, 0.03 to 0.07 wt.% of Sr; 0.08 to 0.12 wt.% of Y; and the balance of Al and inevitable impurities. The 6000-series aluminum alloy profile with high strength and corrosion resistance is obtained through the element ratio correspondence and the process, the static bending intensity of the 6000-series aluminum alloy profile reaches up to 405-435 MPa, the elastic modulus of the 6000-series aluminum alloy profile reaches up to 72-75 GPa, and the impact resistance of the 6000-series aluminum alloy profile reaches up to 43-46 kJ / m.

Description

Technical Field

[0001] This application relates to the field of non-ferrous metal composite materials technology, and more specifically, it relates to a high-strength, alkali-resistant 6000 series aluminum alloy profile, a bumper, and a method for preparing the same. Background Art With the trend towards lightweighting and racing in automobiles, the bumper, as the first line of defense for collision safety, faces the technical challenge of balancing high strength and energy absorption characteristics in its material selection. The current mainstream solution is to use 6000 series aluminum alloy to replace traditional steel, which can meet the requirements of both mechanical performance and lightweight.

[0002] In related technologies, the core material of the 6000 series used in the production of bumpers is mainly 6110A alloy. 6110A alloy is composed of the following components by weight percentage: Si: 0.7%-1.1%, Mg: 0.7%-1.1%, Cu: 0.3%-0.5%, Mn: 0.3%-0.9%, Cr: 0.05%-0.25%, Zn: ≤0.2%, Fe: ≤0.5%, Zr: ≤0.05%, with the balance being Al and unavoidable impurities. The aforementioned 6110A alloy, through optimized alloy ratios and heat treatment processes, exhibits a static bending strength of 320 MPa, an elastic modulus as high as 68 GPa, and an impact resistance of 35 kJ / m. 2 However, its alkali resistance still needs to be improved. Therefore, some companies have increased the copper content to improve the tendency of intergranular corrosion, or increased the chromium content to enhance the stability of the oxide film. However, the additional introduction of these materials generally leads to the degradation of various properties due to the deterioration of the microstructure, and the general goal is to improve acid resistance. Therefore, how to obtain a bumper profile that balances alkali corrosion resistance and mechanical properties has become the core problem to be solved. Based on this, this application provides a high-strength alkali corrosion resistant 6000 series aluminum alloy profile, a bumper, and a method for preparing the same. Summary of the Invention

[0003] This invention, through readjustment of the alloying elements and process optimization of the original 6000 series aluminum alloy profiles, enables the profiles to balance alkali corrosion resistance and mechanical properties, thereby providing a high-strength alkali corrosion resistant 6000 series aluminum alloy profile, bumper, and its preparation method.

[0004] In a first aspect, this application provides a high-strength, alkali-resistant 6000 series aluminum alloy profile, composed of the following components by weight percentage: Si: 0.7-1.1 wt.%; Mg: 0.7-1.1 wt.%; Cu: 0.1-0.8 wt.%; Mn: 0.3-0.9 wt.%; Fe: 0-0.5 wt.%; Sc: 0.1-0.2 wt.%; Sr: 0.03-0.07 wt.%; Y: 0.08-0.12 wt.%; The balance consists of Al and unavoidable impurities.

[0005] Preferably, it consists of the following components by weight percentage: Si: 0.7-1.1 wt.%; Mg: 0.7-1.1 wt.%; Cu: 0.1-0.8 wt.%; Mn: 0.3-0.9 wt.%; Fe: 0-0.5 wt.%; Sc: 0.1 wt.%; Sr: 0.05 wt.%; Y: 0.010 wt.%; The balance consists of Al and unavoidable impurities.

[0006] By adopting the above technical solution and the alloy element ratio, the aluminum alloy profiles obtained have both good mechanical properties and alkali corrosion resistance. Their static bending strength reaches 405-435 MPa, elastic modulus reaches 72-75 GPa, and impact resistance is 43-46 kJ / m. 2 The alkaline corrosion rate is only 0.16-0.20 g / m³. 2 *h; The possible reasons are as follows: This profile is based on the original Al-Mg-Si alloy system. By suppressing the growth of the Mg2Si phase through the segregation of Sr between α-Al dendrites and making the average size of the second phase (Al3(Sc,Sr phase) ≤1μm, equilibrium and stability of the two-phase interface were achieved. The Al3(Sc,Sr) composite nano-precipitates are based on the difference in atomic radii (Zr: 0.160 nm, Sc: 0.161 nm) among (Sc, Y, Zr), which will further induce lattice distortion, thereby increasing its dislocation pinning force and thus ensuring mechanical properties. As for the Y element, it will be enriched at the grain boundaries to form Y-Al-O or form a Y2O3 oxide film on the surface. Compared with adding Cu or Cr elements, thanks to the structure of the Al3(Sc,Sr) composite nano precipitate phase, its grain boundary corrosion sensitivity is weak, which overcomes the defects of the original microstructure deterioration.

[0007] Secondly, this application provides a high-strength, alkali-resistant 6000 series aluminum alloy bumper, which is made from the aforementioned aluminum alloy profile through an extrusion process.

[0008] By adopting the above technical solution, it can be seen that the aluminum alloy profile prepared by the above alloy element ratio can be extruded into bumpers of corresponding specifications, which has the advantages of easy processing and universality, and the corresponding bumper structure can be further improved to enhance its overall mechanical properties.

[0009] Thirdly, this application provides a method for preparing a high-strength, alkali-resistant 6000 series aluminum alloy bumper, comprising the following steps: S1. Smelting and purification: First, the aluminum material is melted and slag is removed. Then, alloys are added and refined according to the composition of the aluminum liquid. After settling, degassing, and filtration, the molten material is purified. S2, Melt casting: The purified melt from S1 is then cast to obtain a cast long bar; S3, Homogenization of casting rods: The long casting rods obtained in S2 are subjected to multi-stage temperature control treatment to obtain casting rod blanks; S4. Hot extrusion molding: The cast billet obtained in S3 is heated and extruded into a bumper billet, and then cooled to room temperature; S5. Dual-stage aging treatment: The profile cooled in S4 is subjected to dual-stage aging treatment to obtain a high-strength, alkali-resistant 6000 series aluminum alloy bumper.

[0010] Preferably, the specific conditions for multi-stage temperature control and homogenization in S3 are as follows: The first-stage temperature is controlled at 500-550℃, and the heat preservation time is 1-3 hours. The second-stage temperature is controlled at 550-600℃, and the heat preservation time is 3-5 hours.

[0011] Preferably, the specific conditions for the two-stage aging heat treatment in S5 are as follows: The first-stage aging temperature is 110-130℃, and the holding time is 2-5 hours. The secondary aging temperature is 160-180℃, and the holding time is 5-8 hours.

[0012] Preferably, the cooling conditions to room temperature in step S4 are as follows: The material is treated to room temperature at -196°C using a 3D contour liquid nitrogen cryogenic device, which includes a cooling chamber adapted to the product and a liquid nitrogen cooling unit.

[0013] Preferably, the specific steps are as follows: S1. Melting and purification: First, the aluminum material is melted and slag is removed. Then, according to the composition of the aluminum liquid, alloying elements other than Y are added and refined. After settling, degassing, and filtration, the molten material purification is completed. S2, Melt casting: The purified melt from S1 is then cast to obtain a cast long bar; S3. Homogenization of casting rods: The long casting rods obtained in S2 are subjected to multi-stage temperature control to obtain casting rod rough billets. The conditions for multi-stage temperature control are as follows: the first stage temperature is controlled at 500-550℃ and the holding time is 1-3h; the second stage temperature is controlled at 550-600℃ and the holding time is 3-5h.

[0014] S4. Hot extrusion molding: The cast billet obtained in S3 is heated and extruded into a bumper billet, and then cooled to room temperature. The specific cooling method is as follows: The material is treated from -196°C to room temperature using a 3D contour liquid nitrogen cryogenic device, which includes a contour cooling chamber adapted to the product and a liquid nitrogen cooling unit. S5. Double-stage aging treatment: The profile cooled in S4 undergoes a double-stage aging treatment to produce a high-strength, alkali-resistant 6000 series aluminum alloy bumper. The conditions for the double-stage aging treatment are as follows: The first-stage aging temperature is 120-150℃, and the holding time is 2-5 hours; the second-stage aging temperature is 150-200℃, and the holding time is 5-8 hours.

[0015] By adopting the above technical solution, in addition to the fact that the parameters and conditions of each stage of the process are easy to control and achieve, the bumper is formed by integral extrusion, so the performance of the resulting bumper is stable and uniform. The multi-stage temperature control homogenization and multi-stage aging treatment under specific conditions are beneficial to the uniformity of its crystal phase structure. Furthermore, the cooling method employed in this application using a specific cooling device has the following advantages: 1) This cooling method can effectively reduce surface stress concentration, reduce the risk of deformation and cracking during subsequent processing or use, and by inhibiting the aggregation of coarse precipitates on the surface and promoting the uniform precipitation of fine dispersed phases, the dimensional stability of the matrix is ​​significantly improved, which is especially significant for precision profiles (such as electronic heat sinks and aerospace structural components). 2) Liquid nitrogen environment is an inert atmosphere that can isolate oxygen and reduce the oxidation reaction on the surface of aluminum after high-temperature extrusion. Cryogenic treatment reduces the surface activity of the material and delays oxidation discoloration (such as gray spots and blackening) during subsequent storage or use. Therefore, it can effectively maintain the metallic luster of the aluminum extrusion profile and reduce the pretreatment cost before subsequent anodizing or spraying.

[0016] In summary, this application has the following beneficial effects: This application achieves a performance breakthrough over traditional 6110A by incorporating Sc, Sr, and Y elements, resulting in a static bending strength of 405-435 MPa, an elastic modulus of 72-75 GPa, and an impact resistance of 43-46 kJ / m. 2 The alkaline corrosion rate is only 0.16-0.20 g / m³. 2 *h; This is mainly due to the balance and synergy between the Mg2Si phase and the Al3(Sc,Sr) composite nano-precipitated phase, and the Y element will be enriched at the grain boundaries to form Y-Al-O or form a Y2O3 oxide film on the surface. Compared to adding Cu or Cr elements, the Al3(Sc,Sr) composite nano-precipitated phase has a weaker sensitivity to grain boundary corrosion due to its structure, which overcomes the defects of the original microstructure deterioration. Furthermore, the use of a 3D contour liquid nitrogen cryogenic device further reduces the concentration of surface stress, effectively reducing the risk of deformation and cracking during subsequent processing or use. In summary, this significantly improves the dimensional stability of the substrate. Attached Figure Description Figure 1 This is a schematic diagram of the overall structure of the bumper in Example 1; Figure 2 This is a cross-sectional structural diagram of the bumper in Example 1; Figure 3 This is a schematic diagram of the overall structure of the 3D contour liquid nitrogen cryogenic device used in this application. Detailed Implementation

[0017] The following is in conjunction with the embodiments and appendices Figure 1-3 This application will be described in further detail.

[0018] Performance testing First, the bumpers from each embodiment and comparative example were selected as test samples. Then, their static bending strength, elastic modulus, impact resistance, and alkali corrosion resistance were tested respectively, as follows: 1. Static bending strength and elastic modulus test 1.1 Sample Pretreatment Sample size: First, prepare 5 parallel samples of the bumper to be tested (length × width × thickness = 1355mm × 115mm × 3mm). Then, place the samples in a constant temperature and humidity chamber (23±2℃, 50±5%RH) for 24 hours to eliminate internal stress.

[0019] 1.2 Three-point bending test (universal testing machine) Testing equipment: Universal testing machine (range ≥ 50kN, accuracy ± 1%); It is equipped with a three-point bending fixture with a span of 48mm and a pressure head radius of 5mm.

[0020] Loading rate: 2 mm / min, continuously loaded until the specimen breaks or reaches 5% strain.

[0021] Data acquisition: Record the load-displacement curves and calculate the following parameters: Static bending strength (MPa): σ=3FL / 2Bh 2, where F is the maximum load, L is the span, and b and h are the width and thickness of the specimen.

[0022] Elastic modulus (GPa): The slope of the linear segment of the stress-strain curve (20-50% of the fracture load).

[0023] Standards based on: ASTM D790-17 (Flexural properties of plastics) and ISO 178:2019.

[0024] 2. Impact resistance test 2.1 Sample Pretreatment Sample specifications: First, cut the bumper to be tested into a standard sample without a notch (length × width × thickness = 200mm × 115mm × 3mm), prepare 5 samples in parallel, and then place the samples in a constant temperature and humidity chamber (23±2℃, 50±5%RH) for 24 hours to eliminate internal stress.

[0025] 2.2 Pendulum Impact Test Test equipment: Pendulum impact testing machine (range ≥15J, conforming to ISO13802 calibration requirements).

[0026] Test conditions: Impact energy: Selected based on the estimated strength of the material (5-10J increments of 1J).

[0027] Impact velocity: 3.5 m / s, pendulum swing angle: 150°.

[0028] Test steps: 1. The specimen is fixed horizontally to the support, with the notch facing away from the impact direction (if applicable).

[0029] 2. Release the pendulum to impact the specimen and record the absorbed energy (unit: kJ / m). 2 ).

[0030] 3. Observe the fracture morphology (ductile / brittle fracture).

[0031] Standards based on: ASTM D6110-18 (Notched Specimen) or ISO 179-1:2023 (Charpy Impact).

[0032] 3. Alkali resistance test - Salt spray test (Alkaline Salt Spray CASS) 3.1 Equipment and Reagents: Salt spray test chamber (temperature control ±1℃, accelerates corrosion) Solution formulation: 5% NaCl + sodium hydroxide, adjusted to pH 9.1-9.3.

[0033] 3.2 Sample preparation: The test was conducted on a full-scale bumper specimen. Its edges were sealed with epoxy resin. After the surface was cleaned with ethanol and dried, it was weighed (accuracy 0.1 mg).

[0034] 3.3 Test conditions: Temperature: 50 ± 2 °C, continuous spraying.

[0035] Time: 240 hours (10 cycle periods).

[0036] Evaluation method: After removing the specimen, it was rinsed with distilled water and dried for 24 hours, and then converted by the weight loss method: corrosion rate (g / m 2 *h), and the test standard was referred to: ASTM B368-09 (CASS).

[0037] Examples 1 - 5 A high-strength alkali-resistant 6000-series aluminum alloy bumper, whose overall structure (length × width × thickness = 1355 mm × 115 mm × 3 mm) is specifically as Figure 1 shown; Its cross-sectional structure is in the shape of a "day character", and the specific dimension specifications are as Figure 2 shown; The components and their corresponding weight percentages of alloy elements in its processed profiles are shown in Table 1 below, and it is obtained through the following steps: S1. Melting and purification: 1) Batching: Return materials ≤ 40%, aluminum ingots ≥ 60%, where the return materials have no oil stains and sewage; the aluminum ingots have a dry surface without stains and no steel strip marks; 2) Charging: First add the return materials with smaller volume, then the return materials with larger volume, and then aluminum ingots and silicon alloy; 3) Melting: Melting is carried out in a feeding furnace at 750 °C. When more than half of the aluminum materials in the furnace are melted, start the electromagnetic stirring to fully stir and melt the aluminum liquid in the furnace; 4) Slag removal: Skimming is carried out at 750 °C, where the total amount of skimming agent per furnace is 10 Kg, and it is evenly scattered into the molten pool. The electromagnetic stirring is turned off during the slag removal process; 5) Adding alloy: When the temperature of the aluminum liquid is 750 °C, first add each alloy element in Table 1 according to the composition test results, and start the electromagnetic stirring; 6) Refining: Then refine the aluminum liquid in step 5), where the total amount of refining agent is 40 Kg / furnace, refined in two times, 20 Kg of refining agent is added each time, and the time is 15 min; 7) Degassing: At 740 °C, degassing for 15 min, and start the electromagnetic stirring; 8) Standing: Standing at 740 °C for 20 min, then turn off the electromagnetic stirring to keep the aluminum liquid stable; 9) Online degassing: set temperature 740℃, rotor speed: 500±10r / min, argon pressure: 0.2MPa, rotor working flow rate: 50L / min, protective gas pressure: 0.2MPa, gas source pressure: 0.5MPa; 10) Online filtration: The chamber temperature is set to 800℃, and the filter plate specifications are 40 mesh + 60 mesh, that is, a 40 mesh filter plate is installed in the aluminum inlet chamber and a 60 mesh filter plate is installed in the aluminum outlet chamber. 11) Cooling: The specific conditions are: water temperature 30℃, water flow rate 220 tons / h.

[0038] S2, Melt Casting: The purified melt from S1 is then cast, with the specific casting conditions as follows: The initial unloading speed is 50 mm / min, and the stable speed is 75 mm / min. After the head of the casting is 300 mm long, the temperature in front of the plate is set to 700℃ and the temperature at the tail of the plate is set to 700℃, thus obtaining the casting long bar.

[0039] S3. Homogenization of casting rods: The long rods are cast using a two-stage temperature-controlled homogenization process in a homogenization furnace. The first stage temperature is controlled at 520℃ and the holding time is 2 hours; the second stage temperature is controlled at 580℃ and the holding time is 4 hours.

[0040] S4. Hot extrusion molding: The cast rod obtained in S3 is heated to 600℃, and then extruded into a bumper blank at an extrusion speed of 5m / min, an extrusion ratio of 20, and an exit temperature of 550℃. Then it is cooled to room temperature at a cooling rate of 5℃ / s.

[0041] S5. Two-stage aging treatment: The profiles cooled in S4 are subjected to two-stage aging treatment. The first-stage aging temperature is 120℃ and the holding time is 4h. The second-stage aging temperature is 170℃ and the holding time is 6h.

[0042] Table 1: Components and their weight percentages in Examples 1-5 Comparative Examples 1-5 A 6000 series aluminum alloy bumper differs from Example 1 in that only the components and their corresponding weight percentages are different, as shown in the table below: Table 2: Components and their weight percentages (wt.%) in Comparative Examples 1-5 Aluminum alloy bumpers from Examples 1-5 and Comparative Examples 1-5 were extracted and tested according to the above steps and standards for their static bending strength, elastic modulus, impact resistance and alkali corrosion resistance. The average values ​​of the test results were recorded in the table below.

[0043] Table: Performance test results of Examples 1-5 and Comparative Examples 1-5 As can be seen from the table above, the aluminum alloy bumpers prepared in Examples 1-5 all have excellent performance, with static bending strength as high as 405-432MPa, elastic modulus as high as 72-75GPa, and impact resistance of 43-46kJ / m. 2 The alkaline corrosion rate is only 0.16-0.20 g / m³. 2 *h; In summary, it is evident that Examples 1-5 all exhibit varying degrees of improvement compared to Comparative Examples 1-5, achieving a balance between strength and alkali corrosion resistance. The reasons for this may be as follows: The profile used in this bumper is based on the original Al-Mg-Si alloy system. By suppressing the growth of the Mg2Si phase through the segregation of Sr between α-Al dendrites, and making the average size of the second phase (Al3(Sc,Sr phase) ≤1μm, a balance and two-phase interface stability are achieved. The Al3(Sc,Sr) composite nano-precipitates are based on the difference in atomic radii (Zr: 0.160 nm, Sc: 0.161 nm) among (Sc, Y, Zr), which will further induce lattice distortion, thereby increasing its dislocation pinning force and thus ensuring mechanical properties. As for the Y element, it will be enriched at the grain boundaries to form Y-Al-O or form a Y2O3 oxide film on the surface. Compared with adding Cu or Cr elements, thanks to the structure of the Al3(Sc,Sr) composite nano precipitate phase, its grain boundary corrosion sensitivity is weak, which overcomes the defects of the original microstructure deterioration.

[0044] Therefore, whether it is the traditional 6082 series or the group that lacks one or two of the elements such as Sc, Zr, and Y, i.e., Comparative Examples 1-5, they all lose the corresponding element ratio effect and do not have the second phase and oxide film mentioned in this application. Moreover, since Comparative Examples 2-5 have omitted the Cr, Zn, and Zr elements in the original 6082 series, their mechanical properties or corrosion resistance are particularly significantly reduced.

[0045] Furthermore, as can be seen from Examples 1-5, Example 4 is the optimal example, and this application can effectively balance the strength and corrosion resistance of aluminum alloy bumpers under the limited proportions of alloying elements. The high-strength, alkali-resistant 6000 series aluminum alloy profile is preferably composed of the following components by weight percentage: Si: 0.7-1.1 wt.%; Mg: 0.7-1.1 wt.%; Cu: 0.1-0.8 wt.%; Mn: 0.3-0.9 wt.%; Fe: 0-0.5 wt.%; Sc: 0.1-0.2 wt.%; Sr: 0.03-0.07 wt.%; Y: 0.08-0.12 wt.%; balance Al and unavoidable impurities.

[0046] Example 6 A high-strength, alkali-resistant 6000 series aluminum alloy bumper differs from Example 4 in that its overall structure, dimensions, and alloy element content are the same, only the manufacturing process is different, as detailed below; S1, Smelting and Purification: 1) Raw material composition: recycled material ≤40%, aluminum ingots ≥60%, of which the recycled material must be free of oil and wastewater; the aluminum ingots must be dry and free of stains and steel strip marks; 2) Feeding: First add smaller volume recycled materials, then larger volume recycled materials, and then aluminum ingots and silicon alloys; 3) Melting: Melting is carried out in the charging furnace at 750℃. When more than half of the aluminum material in the furnace has melted, the electromagnetic stirring is turned on to fully stir and melt the aluminum liquid in the furnace. 4) Slag removal: Slag removal is carried out at 750℃, with a total amount of 10Kg of slag removal agent per furnace, which is evenly sprinkled into the molten pool. Electromagnetic stirring is turned off during the slag removal process. 5) Adding alloys: When the temperature of the molten aluminum reaches 750℃, add all alloying elements except Y in Table 1 according to the composition test results, and turn on the electromagnetic stirrer. 6) Refining: The molten aluminum from step 5) is then refined, with a total refining agent of 40 kg / furnace, in two stages, with 20 kg of refining agent added each time, for 15 minutes. 7) Degassing: Degas at 740℃ for 15 minutes, and turn on the electromagnetic stirrer; 8) Settling: Settle at 740℃ for 20 minutes, then turn off the electromagnetic stir to keep the molten aluminum stable; 9) Online degassing: set temperature 740℃, rotor speed: 500±10r / min, argon pressure: 0.2MPa, rotor working flow rate: 50L / min, protective gas pressure: 0.2MPa, gas source pressure: 0.5MPa; 10) Online filtration: The chamber temperature is set to 800℃, and the filter plate specifications are 40 mesh + 60 mesh, that is, a 40 mesh filter plate is installed in the aluminum inlet chamber and a 60 mesh filter plate is installed in the aluminum outlet chamber. 11) Cooling: The specific conditions are: water temperature 30℃, water flow rate 220 tons / h.

[0047] S2, Melt Casting: The purified melt from S1 is then cast, with the specific casting conditions as follows: The initial unloading speed is 50 mm / min, and the stable speed is 75 mm / min. After the head of the casting is 300 mm long, the temperature in front of the plate is set to 700℃ and the temperature at the tail of the plate is set to 700℃, thus obtaining the casting long bar.

[0048] S3. Homogenization of casting rods: The long rods are cast using a two-stage temperature-controlled homogenization process in a homogenization furnace. The first stage temperature is controlled at 520℃ and the holding time is 2 hours; the second stage temperature is controlled at 580℃ and the holding time is 4 hours.

[0049] S4. Hot extrusion molding: The cast rod obtained in S3 is heated to 600℃, and then extruded into a bumper blank at an extrusion speed of 5m / min, an extrusion ratio of 20, and an exit temperature of 550℃. Then, the material is cooled to room temperature at -196℃ at a rate of 1000-1200℃ / min using a 3D conformal liquid nitrogen cryogenic device. The 3D contour liquid nitrogen cryogenic device includes a shell 1 integrally formed from thermal insulation material and a liquid nitrogen cooling unit 2 disposed inside the shell; The liquid nitrogen cooling unit 2 consists of several liquid nitrogen nozzles distributed within the housing 1; The housing 1 is provided with contoured product transfer ports 3 on both sides, which are adapted to the product. The housing is also provided with a material guiding mechanism 4 adapted to the transfer ports 3 along the discharge direction. The housing 1 is also provided with a pressure relief and exhaust port 5.

[0050] S5. Two-stage aging treatment: The profiles cooled in S4 are subjected to two-stage aging treatment. The first-stage aging temperature is 120℃ and the holding time is 4h. The second-stage aging temperature is 170℃ and the holding time is 6h.

[0051] Extract the aluminum alloy bumper from Example 6 above, and test its static bending strength, elastic modulus, impact resistance and alkali corrosion resistance according to the above steps and standards. The test results are recorded in the table below.

[0052] Table: Performance Test Results of Example 6 As can be seen from the table above, the aluminum alloy bumpers prepared in Example 6 all have excellent performance, with a static bending strength as high as 435 MPa, an elastic modulus as high as 75 GPa, and an impact resistance of 46 kJ / m. 2 The alkaline corrosion rate is only 0.12 g / m³. 2 *h shows varying degrees of improvement compared to Example 4; In summary, it can be seen that the use of a 3D contour-following liquid nitrogen cryogenic device further enhances its various performance characteristics. The specific reasons for this may be as follows: 1) This cooling method can effectively reduce surface stress concentration, reduce the risk of deformation and cracking during subsequent processing or use, and by inhibiting the aggregation of coarse precipitates on the surface and promoting the uniform precipitation of fine dispersed phases, the dimensional stability of the matrix is ​​significantly improved, which is especially significant for precision profiles (such as electronic heat sinks and aerospace structural components). 2) Liquid nitrogen environment is an inert atmosphere that can isolate oxygen and reduce the oxidation reaction on the surface of aluminum after high-temperature extrusion. Cryogenic treatment reduces the surface activity of the material and delays oxidation discoloration (such as gray spots and blackening) during subsequent storage or use. Therefore, it can effectively maintain the metallic luster of the aluminum extrusion profile and reduce the pretreatment cost before subsequent anodizing or spraying.

[0053] Furthermore, it should be noted that the preparation method of the high-strength corrosion-resistant 6000 series aluminum alloy bumper in this application is only based on typical examples 1-5 and 6. Within the preferred range, those skilled in the art can replace the actual alloy element ratio with other operating conditions (temperature, duration, rate), and the changes in various properties can be expected. For ease of review, it will not be elaborated further.

[0054] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A high-strength, alkali-resistant 6000 series aluminum alloy profile, characterized in that, It consists of the following components by weight percentage: Si: 0.7-1.1 wt.%; Mg: 0.7-1.1 wt.%; Cu: 0.1-0.8 wt.%; Mn: 0.3-0.9wt.%; Fe: 0-0.5wt.%; Sc: 0.1-0.2wt.%; Sr: 0.03-0.07wt.%; Y: 0.08-0.12wt.%; The balance consists of Al and unavoidable impurities.

2. The high-strength, alkali-resistant 6000 series aluminum alloy profile according to claim 1, characterized in that, It consists of the following components by weight percentage: Si: 0.7-1.1 wt.%; Mg: 0.7-1.1 wt.%; Cu: 0.1-0.8 wt.%; Mn: 0.3-0.9wt.%; Fe: 0-0.5wt.%; Sc: 0.1wt.%; Sr: 0.005wt.%; Y: 0.010wt.%; The balance consists of Al and unavoidable impurities.

3. A high-strength, alkali-resistant 6000 series aluminum alloy bumper, characterized in that, The aluminum alloy profile described in claim 1 is manufactured by an extrusion process.

4. The method for preparing the high-strength, alkali-resistant 6000 series aluminum alloy bumper as described in claim 3, characterized in that, Includes the following steps: S1. Smelting and purification: First, the aluminum material is melted and slag is removed. Then, alloys are added and refined according to the composition of the aluminum liquid. After settling, degassing, and filtration, the molten material is purified. S2, Melt casting: The purified melt from S1 is then cast to obtain a cast long bar; S3, Homogenization of casting rods: The long casting rods obtained in S2 are subjected to multi-stage temperature control treatment to obtain casting rod blanks; S4. Hot extrusion molding: The cast billet obtained in S3 is heated and extruded into a bumper billet, and then cooled to room temperature; S5. Dual-stage aging treatment: The profile cooled in S4 is subjected to dual-stage aging treatment to obtain a high-strength, alkali-resistant 6000 series aluminum alloy bumper.

5. The method for preparing a high-strength, alkali-resistant 6000 series aluminum alloy bumper according to claim 4, characterized in that, The specific conditions for multi-stage temperature control and homogenization in S3 are as follows: The first-stage temperature is controlled at 500-550℃, and the heat preservation time is 1-3 hours. The second-stage temperature is controlled at 550-600℃, and the heat preservation time is 3-5 hours.

6. The method for preparing a high-strength, alkali-resistant 6000 series aluminum alloy bumper according to claim 4, characterized in that, The specific conditions for the two-stage aging heat treatment in S5 are as follows: The first-stage aging temperature is 120-150℃, and the holding time is 2-5 hours. The secondary aging temperature is 150-200℃, and the holding time is 5-8 hours.

7. The method for preparing a high-strength, alkali-resistant 6000 series aluminum alloy bumper according to claim 4, characterized in that, The conditions for cooling to room temperature in S4 are as follows: The material is treated to room temperature at -196°C using a 3D contour liquid nitrogen cryogenic device, which includes a cooling chamber adapted to the product and a liquid nitrogen cooling unit.

8. The method for preparing a high-strength, alkali-resistant 6000 series aluminum alloy bumper according to claim 7, characterized in that, The specific steps are as follows: S1. Melting and purification: First, the aluminum material is melted and slag is removed. Then, according to the composition of the aluminum liquid, alloying elements other than Y are added and refined. After settling, degassing, and filtration, the molten material purification is completed. S2, Melt casting: The purified melt from S1 is then cast to obtain a cast long bar; S3. Homogenization of casting rods: The long casting rods obtained in S2 are subjected to multi-stage temperature control to obtain casting rod rough billets. The conditions for multi-stage temperature control are as follows: the first stage temperature is controlled at 500-550℃ and the holding time is 1-3h; the second stage temperature is controlled at 550-600℃ and the holding time is 3-5h. 9.S4 Hot Extrusion Molding: The cast billet obtained in S3 is heated and extruded into a bumper billet, and then cooled to room temperature. The specific cooling method is as follows: The material is treated from -196°C to room temperature using a 3D contour liquid nitrogen cryogenic device, which includes a contour cooling chamber adapted to the product and a liquid nitrogen cooling unit. S5. Double-stage aging treatment: The profile cooled in S4 undergoes a double-stage aging treatment to produce a high-strength, alkali-resistant 6000 series aluminum alloy bumper. The conditions for the double-stage aging treatment are as follows: The first-stage aging temperature is 120-150℃, and the holding time is 2-5 hours; the second-stage aging temperature is 150-200℃, and the holding time is 5-8 hours.

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