Production process of high-performance boundary beam profile for 6061 aluminum alloy automobile

Abstract

The invention belongs to the technical field of aluminum alloy production and processing, particularly relates to a production process of a high-performance boundary beam profile for a 6061 aluminum alloy automobile, and aims to solve the problems of serious magnesium element burning loss, unstable hydrogen content control, coarse structure, extrusion deformation, large mechanical property fluctuation, insufficient corrosion resistance and the like in the traditional process. The high requirements of light weight of the new energy automobile on the strength, toughness, forming precision and corrosion resistance of the edge beam are met. The process sequentially comprises the steps of raw material pretreatment, smelting refining, casting passivation, stepped annealing and shot blasting, extrusion forming, segmented air-blast quenching, double-stage aging and finished product treatment. The tensile strength of the final profile is larger than or equal to 260 MPa, the yield strength is larger than or equal to 240 MPa, the elongation is larger than or equal to 12%, the neutral salt spray test is larger than or equal to 500 h, the comprehensive performance is excellent, and the profile is suitable for automobile edge beam key force bearing components.

Description

Technical Field

[0001] This invention belongs to the field of aluminum alloy production and processing technology, and in particular relates to a production process for a high-performance side beam profile of 6061 aluminum alloy for automobiles. Background Technology

[0002] With the development of new energy vehicles and lightweight vehicle structures, higher requirements are placed on the strength, toughness, corrosion resistance, and forming precision of vehicle body structural components. As a key load-bearing component of the vehicle body frame, automotive side beams must possess excellent tensile strength, yield strength, and good fatigue resistance, while also meeting the corrosion resistance requirements of complex cross-section forming and long-term service environments. 6061 aluminum alloy is widely used in automotive structural components due to its excellent comprehensive properties, but traditional production processes have many problems: First, severe magnesium loss and unstable hydrogen content control during smelting easily lead to porosity and compositional segregation; second, coarse casting structure and uneven composition affect subsequent processing performance; third, improper temperature and speed control during extrusion molding easily cause profile deformation and residual stress concentration; finally, fixed heat treatment process parameters make it difficult to achieve precise control of the strengthening phase, resulting in large fluctuations in mechanical properties, making it difficult to meet the stringent requirements of consistency and reliability for high-performance side beams. Therefore, a new production process that can systematically optimize the entire process from raw materials to finished products is urgently needed to comprehensively improve the overall performance of 6061 aluminum alloy side beam profiles and meet the demands of the modern automotive industry for high-performance lightweight structural materials. Summary of the Invention

[0003] To address the issue of inconsistent product quality in existing processes, this invention aims to propose a production process for high-performance side beam profiles made of 6061 aluminum alloy for automobiles. By optimizing key processes such as raw material pretreatment, precision melting and refining, electromagnetic stirring casting, stepped annealing, dynamic control extrusion, segmented air-cooling quenching, two-stage aging based on the JMAK model, and enhanced surface treatment, this invention overcomes problems in existing 6061 aluminum alloy side beam profile production processes, including unstable composition control, coarse microstructure, high quenching stress, large fluctuations in mechanical properties, and insufficient corrosion resistance.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0005] A manufacturing process for a high-performance side beam profile made of 6061 aluminum alloy for automobiles includes the following steps:

[0006] 1. Raw material pretreatment

[0007] Si raw material: Use 25mm granules, pre-melted under vacuum at 600~620℃ for 1.5~2h to avoid compositional segregation caused by uneven particle size during melting; Ti raw material: Added as a Ti-Al master alloy with 10% Ti content, dried at 300~320℃ for 2.5~3h to remove adsorbed moisture on the alloy surface and prevent hydrogen pores from being generated during melting; Al raw material: Use 5% nitric acid solution as a cleaning agent and ultrasonically clean at 40~50℃ for 15~20min to thoroughly remove surface oxide film, oil and other impurities, and avoid introducing impurities that affect the purity of the material. The composition is strictly controlled by weight percentage: Si 0.45~0.65%, Fe≤0.20%, Cu 0.16~0.30%, Mn≤0.10%, Mg 0.81~0.95% (with an additional 0.03~0.05% compensation to offset Mg loss during smelting), Cr≤0.15%, Zn≤0.10%, Ti≤0.10%, and other individual impurity elements ≤0.05%, total ≤0.10%, to ensure that the composition meets the high purity requirements of automotive aluminum alloys.

[0008] 2. Smelting and refining

[0009] First, Al raw material is added to a medium-frequency induction furnace and heated to 680-700℃ to completely melt it, providing a uniform matrix for the subsequent dissolution of alloying elements. Si, Cu, and Mn are then added, and the temperature is raised to 720-740℃, stirred at a speed of 50-80 r / min to ensure uniform diffusion of the alloying elements. Finally, easily burnable Mg, Cr, and Ti are added, and the temperature is lowered to 710-720℃ and held for 30-40 min to reduce high-temperature burn-off of Mg while ensuring complete dissolution of Cr and Ti. Argon gas with a purity ≥99.99% is introduced into the melt at a flow rate of 0.8-1.2 L / min, while simultaneously adding... A composite refining agent, mixed with KCl at a mass ratio of 3:1, is used at a dosage of 1.2~1.4 kg / T of aluminum raw material. The mixture is kept at 720~730℃ for 20~25 min. Through the flotation effect of argon bubbles and the adsorption effect of the refining agent, hydrogen and non-metallic inclusions in the melt are removed. A two-stage filtration structure is adopted, consisting of a 150-mesh ceramic filter plate (coarse filtration, removing large-sized inclusions) and a 300-mesh foam ceramic filter plate (fine filtration, removing small inclusions). The final hydrogen content of the melt is controlled to be ≤0.15 mL / 100 g, which significantly reduces porosity and inclusion defects in the finished product.

[0010] 3. Casting and passivation

[0011] A semi-continuous casting machine is used, with a casting speed of 80~100mm / min and a cooling water pressure of 0.3~0.4MPa, to ensure the quality of the cast rod (diameter...). Rapid and uniform cooling (180~220mm); turn on the electromagnetic stirring device (magnetic field strength 0.08~0.12T, frequency 50~60Hz), and calculate the stirring intensity using a magnetohydrodynamic model:

[0012]

[0013] in, The magnetic Reynolds number, The permeability of free space, For electrical conductivity, Let B be the angular frequency, B be the magnetic field strength, and L be the characteristic length. For density, For dynamic viscosity; by adjusting B and make Above the critical value, dendrite growth is broken, grains are refined, and compositional segregation is avoided; after the cast rod is cooled to room temperature, it is immersed in a silane treatment solution with a concentration of 58% and a temperature of 25~30℃ for 10~15 minutes to form a passivation film with a thickness of 1~2μm on the surface. This film can isolate air and moisture, providing protection for subsequent annealing, shot peening and other processes, and reducing surface oxidation.

[0014] 4. Stepped annealing and shot peening

[0015] The cast ingot is placed in a continuous annealing furnace, first heated to 400~420℃ and held for 2~3 hours to eliminate casting internal stress and promote solute atom diffusion. Then, the temperature is raised to 540~560℃ and held for 5~6 hours to further refine the microstructure and prepare for subsequent extrusion. Subsequently, the temperature is reduced to 300~320℃ by air cooling at a rate of 15~20℃ / h, and finally cooled to room temperature by water spraying to avoid rapid cooling and the generation of new internal stress. After sawing the cast ingot to a length of 600~800mm, it is shot peened with steel shot with a particle size of 0.1~0.3mm at a pressure of 0.2~0.3MPa for 3~5 minutes to form a work-hardened layer on the surface of the ingot, increasing the surface hardness to 80~85HB. At the same time, the surface oxide scale is removed, increasing the adhesion to the die during subsequent extrusion.

[0016] 5. Extrusion molding

[0017] The bar stock is fed into a tunnel furnace and heated to 460~470℃, held for 1~1.5 hours, strictly controlling the temperature difference between the inside and outside of the bar stock to ≤5℃ to avoid inconsistent deformation due to uneven temperature during extrusion. The extrusion die is made of H13 steel and coated with a 5~8μm thick boron nitride lubricating coating to reduce friction between the die and the profile, extending die life. The die is heated to 500~510℃ and held for 1.5~2 hours to ensure stable die temperature. The extrusion cylinder temperature is controlled at 440~460℃ to reduce extrusion resistance. The initial extrusion speed is set to 3.5~4.5m / min. The extrusion pressure is monitored in real time during extrusion, with a target value of 250~280MPa. When the pressure fluctuation exceeds ±10MPa, the speed is dynamically adjusted using the following formula:

[0018] Conventional cross-section (moment of inertia) ):

[0019]

[0020] in, For real-time speed, The initial velocity, The adjustment coefficient is 0.6~0.8. For real-time pressure, For target pressure;

[0021] Thin cross section (moment of inertia) ): Based on the above formula, add a section correction term, that is:

[0022]

[0023] To avoid overheating and deformation of thin parts due to excessive speed; ultimately ensure that the dimensional tolerance of the profile is ≤ ±0.1mm to meet the assembly accuracy requirements of automotive side beams.

[0024] 6. Segmented air-cooling quenching

[0025] After extrusion, the profiles are cooled in stages using a segmented air-cooling mode to avoid uneven microstructure caused by a single cooling method: High-strength air-cooling zone: air volume 90~95%, air velocity 15~18m / s, cooling rate ≥150℃ / min, rapidly reducing the profile temperature from extrusion temperature to 200~220℃, suppressing... The early precipitation of the phase provides solute atoms for subsequent aging strengthening; low-intensity air-cooling zone: air volume 50~60%, air speed 8~10m / s, slowly reducing the temperature of the profile from 200~220℃ to 80~90℃, reducing quenching internal stress; a laser diameter gauge is used to detect the cross-sectional dimensions in real time, and a portable hardness tester is used to check the surface hardness, requiring ≥90HB, and unqualified products are directly rejected to avoid flowing into subsequent processes.

[0026] 7. Two-stage time limit

[0027] First stage aging: Heat to 120~130℃ and hold for 3~4 hours to promote aging. The nucleation of the phase leads to the formation of numerous small metastable phases;

[0028] The second stage of aging involves heating to 170-180℃ and holding for 5-6 hours to transform the metastable phase into a stable strengthening phase. Simultaneously, the JMAK model is used to determine the process.

[0029]

[0030] in, The fraction of precipitate phase transformation (≥0.95). The rate constant is For time, The Avrami exponent (1.5~2.0), combined with the Arrhenius equation:

[0031]

[0032] Pre-exponential factor ( ), The activation energy is 120~150kJ / mol. It is the gas constant (8.314 J / molK). The absolute temperature is used to dynamically adjust the aging parameters; after aging, the temperature is lowered to 80~90℃ and held for 2~3 hours, then air-cooled to room temperature to further stabilize the microstructure, ultimately ensuring that the tensile strength of the profile is ≥260MPa and the yield strength is ≥240MPa, meeting the load-bearing requirements of automotive side beams.

[0033] 8. Finished Product Processing

[0034] Degreasing: Clean the profile with a 5% sodium hydroxide solution at 40~50℃ to remove surface oil and dirt;

[0035] Pickling: Neutralize the residual alkali solution from degreasing with a 10% nitric acid solution at room temperature, while removing the slight oxide film on the surface to prepare for anodizing;

[0036] Anodizing: Treat at 18~20V for 30~40min to form an oxide film with a thickness of 5~8μm on the profile surface;

[0037] Sealing: A nickel salt solution is used to seal the pores of the oxide film and isolate it from corrosive media;

[0038] The processed profiles are subjected to performance sampling inspection. 3-5 profiles are randomly selected from each batch and tested for elongation ≥12% (to ensure toughness and avoid brittle fracture), bending angle ≥90° without cracks (to ensure formability), and neutral salt spray test ≥500h (to verify corrosion resistance and suitability for automotive outdoor use environment).

[0039] The present invention has the following beneficial effects:

[0040] 1. Significantly improved mechanical properties: Through precise composition control, uniform and refined as-cast microstructure, and a two-stage aging process optimized based on the JMAK model, the profile achieves excellent comprehensive mechanical properties, with tensile strength ≥260MPa, yield strength ≥240MPa, and elongation ≥12%, meeting the high standards required for automotive side beams in terms of collision safety and load-bearing capacity.

[0041] 2. Uniform structure: Raw material pretreatment and compound refining + two-stage filtration technology effectively reduce the hydrogen content (≤0.15mL / 100g) and non-metallic inclusions in the melt; electromagnetic stirring combined with magnetohydrodynamic model control significantly refines the grains, avoids segregation, and improves the internal quality of the material.

[0042] 3. High dimensional accuracy: It adopts dynamic extrusion speed adjustment technology, which automatically adjusts the extrusion parameters according to real-time pressure feedback. In particular, it introduces a moment of inertia correction term for thin sections to effectively prevent overheating deformation and ensure that the dimensional tolerance of the profile is controlled within ±0.1mm, meeting the requirements of high-precision assembly.

[0043] 4. Low quenching stress and small deformation: The segmented air-cooling quenching process achieves a balance between rapid cooling and stress release. Rapid overcooling in the high-strength zone inhibits premature precipitation, while slow cooling in the low-strength zone reduces internal stress, thus avoiding quenching cracks and warping deformation.

[0044] 5. Excellent corrosion resistance: Silane passivation pretreatment effectively prevents oxidation during intermediate processes; anodic oxidation + nickel salt sealing forms a dense and stable oxide film (5~8μm), which has been verified by neutral salt spray test to have a corrosion resistance of ≥500h, making it suitable for complex and variable automotive operating environments. Attached Figure Description

[0045] Figure 1 Metallographic image of aluminum alloy for the production process of a high-performance side beam profile for automobiles made of 6061 aluminum alloy proposed in this invention. Detailed Implementation

[0046] The present invention will be further described in detail below with reference to specific embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0047] This embodiment uses the production of φ200mm cast rods with a cross-sectional moment of inertia. Taking aluminum alloy automotive side beam profiles as an example, the production steps are as follows:

[0048] S1 raw material pretreatment: Si raw material is vacuum pre-melted at 600~620℃ for 1.5~2h, Ti raw material is dried at 300~320℃ for 2.5~3h in the form of Ti-Al master alloy, and Al raw material is ultrasonically cleaned at 40~50℃. The raw material is then formulated according to the following weight percentages: Si 0.45~0.65%, Fe≤0.20%, Cu 0.16~0.30%, Mn≤0.10%, Mg 0.81~0.95%, Cr≤0.15%, Zn≤0.10%, Ti≤0.10%, with the balance being Al; other individual elements ≤0.05%, total ≤0.10%. An additional 0.03~0.05% compensation amount is reserved for Mg raw material.

[0049] S2 Smelting and Refining: First, put Al raw material into a medium-frequency induction furnace and heat it to 680~700℃ for pre-melting. After Al is completely melted, add Si, Cu, and Mn and heat it to 720~740℃ for main melting. Stir at a speed of 50~80 r / min. Finally, add Mg, Cr, and Ti and cool it to 710~720℃ and hold for 30~40 min. Introduce argon gas into the melt and add a composite refining agent. After two-stage tubular filtration, control the hydrogen content to ≤0.15mL / 100g.

[0050] S3 Casting and Passivation: A semi-continuous casting machine is used. During the casting process, an electromagnetic stirring device is turned on to cast liquid aluminum alloy into a casting rod. After the casting rod is cooled to room temperature, it is immersed in silane treatment solution to form a passivation film.

[0051] S4 stepped annealing and shot peening: The casting rod is placed in a continuous annealing furnace, heated to 400~420℃ and held for 2~3 hours, then heated to 540~560℃ and held for 5~6 hours, air-cooled to 300~320℃ and then sprayed with water to cool, sawed and shot peening.

[0052] S5 Extrusion Molding: The shot-peened bar stock is sent to a tunnel heating furnace for preheating, heated to 460~470℃ and held for 1~1.5h, and then put into an extruder for extrusion. The extrusion die is heated to 500~510℃ and held for 1.5~2h and a lubricating coating is sprayed. The extrusion cylinder temperature is 440~460℃ and the extrusion speed is 3.5~4.5m / min.

[0053] S6 segmented air-cooled quenching: After the profile is extruded, it is first cooled to 200~220℃ in a high-strength air-cooling zone, and then cooled to 80~90℃ in a low-strength air-cooling zone. After quenching, the dimensions and hardness are tested online.

[0054] S7 Dual-Stage Aging: Qualified profiles are sent into an aging furnace, heated to 120~130℃ and held for 3~4 hours, then heated to 170~180℃ and held for 5~6 hours. After aging, the profiles are cooled to 80~90℃ and held for 2~3 hours, and then air-cooled to room temperature.

[0055] S8 Finished Product Processing: After degreasing and pickling, the profiles undergo anodizing to form an oxide film with a thickness of 5~8μm. Finally, the holes are sealed with a sealing agent, and the mechanical properties and corrosion resistance are tested by random sampling.

[0056] In S1, the particle size of Si raw material is 2~5mm, the cleaning agent for ultrasonic cleaning is 5% nitric acid solution, and the cleaning time is 15~20min; the Ti content in Ti-Al master alloy is 10%.

[0057] In S2, the argon purity is ≥99.99%, and the flow rate is 0.8~1.2 L / min; the composite refining agent is... Mix with KCl at a mass ratio of 3:1, using 1.2~1.4Kg / T of aluminum raw material, refining at 720~730℃, and holding for 20~25min; the two-stage tubular filtration consists of a first-stage 150-mesh ceramic filter plate and a second-stage 300-mesh foam ceramic filter plate.

[0058] In S3, the magnetic field strength of the electromagnetic stirring device is 0.08~0.12T, and the frequency is 50~60Hz; the casting speed is 80~100mm / min, the cooling water pressure is 0.3~0.4MPa, and the diameter of the casting rod is... 180~220mm; silane treatment solution concentration 5~8%, temperature 25~30℃, immersion time 10~15min, passivation film thickness 1~2μm.

[0059] Stirring intensity is calculated based on a magnetohydrodynamic model to ensure uniform microstructure.

[0060]

[0061] in, The magnetic Reynolds number, The permeability of free space, For electrical conductivity, Let B be the angular frequency, B be the magnetic field strength, and L be the characteristic length. For density, For dynamic viscosity; by adjusting B and make Above the critical value, avoid segregation.

[0062] In S4, the air cooling rate for stepped annealing is 15~20℃ / h; the length of the sawn bar is 600~800mm; the steel shot used for shot peening is 0.1~0.3mm in size, 0.2~0.3MPa in pressure, and 3~5min in time, resulting in a surface hardness of 80~85HB for the bar after shot peening.

[0063] In S5, the internal and external temperature difference during bar preheating is ≤5℃; the extrusion die is made of H13 steel, and the lubricating coating is a boron nitride coating with a thickness of 5~8μm; the extrusion pressure is monitored in real time during the extrusion process and controlled at 250~280MPa. When the pressure fluctuation exceeds ±10MPa, the extrusion speed is automatically adjusted to ensure that the profile dimensional tolerance is ≤±0.1mm. The dynamic adjustment formula for the extrusion speed is:

[0064]

[0065] in: For real-time extrusion speed; This is the initial extrusion speed; The speed adjustment coefficient is set to 0.6~0.8, and is determined based on the complexity of the profile cross-section. For real-time extrusion pressure; The target extrusion pressure; when the moment of inertia of the profile section... At that time, an additional section correction term is added to the dynamic adjustment formula for extrusion speed:

[0066]

[0067] To prevent thin profiles from overheating due to excessive speed.

[0068] In S6, the air volume in the high-intensity air-cooled zone is 90~95%, the air velocity is 15~18m / s, and the cooling rate is ≥150℃ / min; the air volume in the low-intensity air-cooled zone is 50~60%, and the air velocity is 8~10m / s; online detection uses a laser diameter gauge to detect the cross-sectional dimensions, and a portable hardness tester is used to randomly check the surface hardness, which is required to be ≥90HB.

[0069] In S7, the two-stage aging process uses the JMAK model to optimize the aging process parameters. The model formula is as follows:

[0070]

[0071] in, The precipitation phase inversion fraction has a target value ≥ 0.95; It is the rate constant; For time; The Avrami exponent has a value ranging from 1.5 to 2.0; the rate constant. With temperature The relationship follows the Arrhenius equation:

[0072]

[0073] in, The pre-exponential factor takes the value of ; The activation energy is set at 120~150 kJ / mol. This is the gas constant, with a value of 8.314 J / molK; The absolute temperature is used; through model calculation, the aging temperature and holding time are dynamically adjusted to ensure that the tensile strength of the profile after two-stage aging is ≥260MPa and the yield strength is ≥240MPa.

[0074] In S8, degreasing is performed using a 5% sodium hydroxide solution at a temperature of 40-50℃; pickling is performed using a 10% nitric acid solution at room temperature; anodizing voltage is 18-20V for 30-40 minutes; the sealing agent is a nickel salt solution; for performance sampling, 3-5 profiles are randomly selected from each batch, and the elongation is tested to be ≥12%, the bending angle is ≥90° without cracks, and the neutral salt spray test is ≥500h.

[0075] Finished product processing and sampling inspection

[0076] Surface treatment: The profile is first degreased in a 5% sodium hydroxide solution at 45℃ for 15 minutes (to remove surface oil stains), then rinsed with deionized water; then pickled in a 10% nitric acid solution at room temperature for 10 minutes (to neutralize residual alkali and remove slight oxide film), and rinsed again until neutral; then anodizing is performed: voltage 19V, time 35 minutes, to form an oxide film with a thickness of 6.5μm; finally, nickel salt solution is used to seal the pores for 20 minutes (to fill the pores of the oxide film and improve corrosion resistance).

[0077] For the production of 6061 aluminum alloy automotive side impact beam profiles, the above process is implemented: S1 Pretreatment of raw materials: Si raw materials are vacuum pre-melted at 610℃ for 1.8h, Ti-Al master alloy is dried at 310℃ for 2.8h, and Al raw materials are ultrasonically cleaned at 45℃; the raw materials are proportioned as follows: Si 0.55%, Fe 0.15%, Cu 0.23%, Mn 0.08%, Mg 0.88% (with a 0.04% compensation allowance), Cr 0.12%, Zn 0.07%, Ti 0.08%, and other impurities ≤0.03% each, totaling 0.08%, with the balance being Al. S2 Melting: Al material is pre-melted in a medium-frequency furnace at 690℃, Si is added and the temperature is raised to 730℃ for main melting (stirring at 65r / min), Mg is added and the temperature is lowered to 715℃ and held for 35min; Argon gas is introduced and a composite refining agent is added, and after double-stage filtration, the hydrogen content is 0.12mL / 100g. S3 Semi-continuous casting and electromagnetic stirring to form a cast rod, followed by silane impregnation to form a passivation film after cooling. S4 Step annealing: 410℃ for 2.5h → 550℃ for 5.5h, air-cooled to 310℃, then water-cooled, sawed, and shot-peened. S5 Extrusion: Rod stock held at 465℃ for 1.2h, die held at 505℃ for 1.8h, lubricated coating applied, extruded at 450℃ in the extrusion cylinder at a speed of 4m / min. S6 Segmented air cooling: first cooled to 210℃, then cooled to 85℃, and passed online inspection. S7 Two-stage aging: 125℃ for 3.5h → 175℃ for 5.5h, cooled to 85℃ for 2.5h, then air-cooled. S8 Finished product treatment: degreasing, pickling, anodizing (6μm oxide film), and sealing.

[0078] Test results:

[0079] 1. Ingredients meet standards;

[0080] 2. Dimensional tolerance ±0.1mm, meeting assembly requirements;

[0081] 3. Tensile strength 310MPa, yield strength 275MPa, elongation 15%; 4. Oxide film adhesion grade 2, no rust after 72h neutral salt spray test, meeting the mechanical and corrosion resistance requirements of automotive side beams.

[0082] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A manufacturing process for a high-performance side beam profile of 6061 aluminum alloy for automobiles, characterized in that: The production steps are as follows: S1 raw material pretreatment: Si raw material is vacuum pre-melted at 600~620℃ for 1.5~2h, Ti raw material is dried at 300~320℃ for 2.5~3h in the form of Ti-Al master alloy, and Al raw material is ultrasonically cleaned at 40~50℃. The raw material is then formulated according to the following weight percentages: Si 0.45~0.65%, Fe≤0.20%, Cu 0.16~0.30%, Mn≤0.10%, Mg 0.81~0.95%, Cr≤0.15%, Zn≤0.10%, Ti≤0.10%, with the balance being Al; other individual elements ≤0.05%, total ≤0.10%. An additional 0.03~0.05% compensation amount is reserved for Mg raw material. S2 Smelting and Refining: First, put Al raw material into a medium-frequency induction furnace and heat it to 680~700℃ for pre-melting. After Al is completely melted, add Si, Cu, and Mn and heat it to 720~740℃ for main melting. Stir at a speed of 50~80 r / min. Finally, add Mg, Cr, and Ti and cool it to 710~720℃ and hold for 30~40 min. Introduce argon gas into the melt and add a composite refining agent. After two-stage tubular filtration, control the hydrogen content to ≤0.15mL / 100g. S3 Casting and Passivation: A semi-continuous casting machine is used. During the casting process, an electromagnetic stirring device is turned on to cast liquid aluminum alloy into a casting rod. After the casting rod is cooled to room temperature, it is immersed in silane treatment solution to form a passivation film. S4 stepped annealing and shot peening: The casting rod is placed in a continuous annealing furnace, heated to 400~420℃ and held for 2~3 hours, then heated to 540~560℃ and held for 5~6 hours, air-cooled to 300~320℃ and then sprayed with water to cool, sawed and shot peening. S5 Extrusion Molding: The shot-peened bar stock is sent to a tunnel heating furnace for preheating, heated to 460~470℃ and held for 1~1.5h, and then put into an extruder for extrusion. The extrusion die is heated to 500~510℃ and held for 1.5~2h and a lubricating coating is sprayed. The extrusion cylinder temperature is 440~460℃ and the extrusion speed is 3.5~4.5m / min. S6 segmented air-cooled quenching: After the profile is extruded, it is first cooled to 200~220℃ in a high-strength air-cooling zone, and then cooled to 80~90℃ in a low-strength air-cooling zone. After quenching, the dimensions and hardness are tested online. S7 Dual-Stage Aging: Qualified profiles are sent into an aging furnace, heated to 120~130℃ and held for 3~4 hours, then heated to 170~180℃ and held for 5~6 hours. After aging, the profiles are cooled to 80~90℃ and held for 2~3 hours, and then air-cooled to room temperature. S8 Finished Product Processing: After degreasing and pickling, the profiles undergo anodizing to form an oxide film with a thickness of 5~8μm. Finally, the holes are sealed with a sealing agent, and the mechanical properties and corrosion resistance are tested by random sampling.

2. The manufacturing process of a 6061 aluminum alloy high-performance side beam profile for automobiles according to claim 1, characterized in that: In S1, the particle size of the Si raw material is 2~5mm, the ultrasonic cleaning agent is 5% nitric acid solution, and the cleaning time is 15~20min; the Ti content in the Ti-Al master alloy is 10%.

3. The manufacturing process of a 6061 aluminum alloy high-performance automotive side beam profile according to claim 1, characterized in that: In S2, the argon gas has a purity ≥99.99% and a flow rate of 0.8~1.2 L / min; the composite refining agent is... It is mixed with KCl at a mass ratio of 3:1, with a dosage of 1.2~1.4Kg / T of aluminum raw material, and the refining temperature is 720~730℃, and the holding time is 20~25min; the dual-stage tubular filter consists of a first-stage 150-mesh ceramic filter plate and a second-stage 300-mesh foam ceramic filter plate.

4. The manufacturing process of a 6061 aluminum alloy high-performance side beam profile for automobiles according to claim 1, characterized in that: In S3, the magnetic field strength of the electromagnetic stirring device is 0.08~0.12T, and the frequency is 50~60Hz; the casting speed is 80~100mm / min, the cooling water pressure is 0.3~0.4MPa, and the diameter of the casting rod is... 180~220mm; the concentration of the silane treatment solution is 5~8%, the temperature is 25~30℃, the soaking time is 10~15min, and the passivation film thickness is 1~2μm.

5. The manufacturing process of a 6061 aluminum alloy high-performance side beam profile for automobiles according to claim 1, characterized in that: In S3, the stirring intensity is calculated based on a magnetohydrodynamic model to ensure uniformity of the microstructure: in, The magnetic Reynolds number, The permeability of free space, For electrical conductivity, Let B be the angular frequency, B be the magnetic field strength, and L be the characteristic length. For density, For dynamic viscosity; by adjusting B and make Above the critical value, avoid segregation.

6. The manufacturing process of a 6061 aluminum alloy high-performance side beam profile for automobiles according to claim 1, characterized in that: In S4, the air cooling rate of the stepped annealing is 15~20℃ / h; the length of the bar after sawing is 600~800mm; the steel shot used for shot peening has a particle size of 0.1~0.3mm, a pressure of 0.2~0.3MPa, a time of 3~5min, and the surface hardness of the bar after shot peening is 80~85HB.

7. The manufacturing process of a 6061 aluminum alloy high-performance side beam profile for automobiles according to claim 1, characterized in that: In S5, the internal and external temperature difference during bar preheating is ≤5℃; the extrusion die is made of H13 steel, and the lubricating coating is a boron nitride coating with a thickness of 5~8μm; the extrusion pressure is monitored in real time during the extrusion process and controlled at 250~280MPa. When the pressure fluctuation exceeds ±10MPa, the extrusion speed is automatically adjusted to ensure that the profile dimensional tolerance is ≤±0.1mm. The dynamic adjustment formula for the extrusion speed is: in: For real-time extrusion speed; This is the initial extrusion speed; The speed adjustment coefficient is set to 0.6~0.8, and is determined based on the complexity of the profile cross-section. For real-time extrusion pressure; The target extrusion pressure; when the moment of inertia of the profile section... At that time, an additional section correction term is added to the dynamic adjustment formula for extrusion speed: To prevent thin profiles from overheating due to excessive speed.

8. The manufacturing process of a 6061 aluminum alloy high-performance side beam profile for automobiles according to claim 1, characterized in that: In S6, the air volume of the high-intensity air-cooling zone is 90-95%, the air speed is 15-18m / s, and the cooling rate is ≥150℃ / min; the air volume of the low-intensity air-cooling zone is 50-60%, and the air speed is 8-10m / s. Online inspection uses a laser diameter gauge to measure cross-sectional dimensions, and a portable hardness tester to randomly check surface hardness, requiring ≥90HB.

9. The manufacturing process of a 6061 aluminum alloy high-performance side beam profile for automobiles according to claim 1, characterized in that: In S7, the two-stage aging process uses the JMAK model to optimize the aging process parameters. The model formula is as follows: in, The precipitation phase inversion fraction has a target value ≥ 0.95; It is the rate constant; For time; The Avrami exponent has a value ranging from 1.5 to 2.0; the rate constant. With temperature The relationship follows the Arrhenius equation: in, The pre-exponential factor takes the value of ; The activation energy is set at 120~150 kJ / mol. This is the gas constant, with a value of 8.314 J / molK; The absolute temperature is used; through model calculation, the aging temperature and holding time are dynamically adjusted to ensure that the tensile strength of the profile after two-stage aging is ≥260MPa and the yield strength is ≥240MPa.

10. The manufacturing process of a 6061 aluminum alloy high-performance side beam profile for automobiles according to claim 1, characterized in that: In S8, the degreasing is performed using a 5% sodium hydroxide solution at a temperature of 40-50℃; the pickling is performed using a 10% nitric acid solution at room temperature; the anodizing voltage is 18-20V for 30-40 minutes; the sealing agent is a nickel salt solution; for performance sampling, 3-5 profiles are randomly selected from each batch, and the elongation is tested to be ≥12%, the bending angle is ≥90° without cracks, and the neutral salt spray test is ≥500h.

Images