A method for manufacturing a deformation-resistant vehicle-mounted aluminum load-bearing component

Abstract

This invention discloses a method for preparing deformation-resistant automotive aluminum load-bearing components. The method employs a composite process including precise alloy proportioning, segmented homogeneous melting, gradient temperature-controlled extrusion, multi-stage online quenching, prestressed shaping and aging, and surface strengthening. By limiting precise process parameters for each step, the method refines the internal grains of the aluminum alloy, eliminates internal residual stress, and constructs a dense and strengthened surface layer, effectively improving the component's resistance to alternating deformation and impact deformation. This invention offers strong process controllability, a high finished product qualification rate, and produces load-bearing components with excellent dimensional stability, suitable for long-term adaptation to complex automotive load-bearing conditions. It is applicable to the mass production of various load-bearing aluminum components for automotive chassis, luggage racks, and vehicle support bases.

Description

Technical Field

[0001] This invention belongs to the field of automotive aluminum component manufacturing technology, specifically relating to a method for manufacturing a deformation-resistant automotive aluminum load-bearing component. Background Technology

[0002] Existing conventional manufacturing processes for automotive aluminum load-bearing components generally suffer from incomplete process systems and unreasonable parameter matching. The resulting aluminum load-bearing components have poor internal structural stability and can only meet the static low load-bearing requirements. Under long-term alternating loads, high-frequency bumps and impacts, and continuous torsional stress conditions during vehicle operation, they are prone to plastic deformation and stress relaxation deformation, resulting in defects such as reduced component dimensional accuracy, decreased load-bearing stability, and short service life. This is the core technical problem of existing technologies.

[0003] Specifically, the existing manufacturing process has several key shortcomings that lead to the aforementioned technical problems: First, the alloy composition is simple and crude, failing to optimize the trace element ratio for dynamic load-bearing conditions in vehicles. The imbalance in the content of strengthening elements such as Si, Mg, Mn, and Cr prevents the formation of uniform and dense strengthening precipitates, resulting in weak shear and impact resistance of the alloy matrix. Second, the use of a one-time integral melting process, with simultaneous melting of high and low melting point elements, easily leads to the burn-off of low melting point elements and insufficient melting of high melting point elements, causing alloy composition segregation and large differences in local mechanical properties of the components, making them prone to local deformation under stress. Third, the use of only a single low-temperature homogenization treatment cannot completely eliminate the residual stress of ingot casting, resulting in poor grain refinement and uneven grain size, leading to insufficient overall structural stability of the components. Fourth, the low precision of temperature control and fixed extrusion parameters in extrusion molding result in uneven metal flow during molding, generating new residual extrusion stress inside the components. The combination of these various process defects ultimately results in the inability of existing automotive aluminum load-bearing components to adapt to the complex dynamic load-bearing conditions of vehicles. After long-term use, deformation problems become prominent, and the reliability and durability cannot meet the requirements of high-end vehicles for lightweight and highly stable load-bearing applications. Summary of the Invention

[0004] The purpose of this invention is to address the technical problem that existing automotive aluminum load-bearing components are prone to plastic deformation and stress relaxation deformation under long-term alternating loads and bumpy impact conditions. This invention provides a method for preparing deformation-resistant automotive aluminum load-bearing components. By optimizing the precise alloy proportioning, segmented melting, two-stage homogenization, gradient extrusion, multi-stage quenching, segmented aging, and surface strengthening processes, the internal microstructure of the component is comprehensively optimized, residual stress is eliminated, and overall mechanical stability is improved. This fundamentally solves the problem of deformation failure under long-term operating conditions, significantly improving the deformation resistance, dimensional stability, and service life of automotive aluminum load-bearing components.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A method for manufacturing a deformation-resistant vehicle-mounted aluminum load-bearing component includes the following steps: Step S1, alloy raw material ratio: the raw materials are proportioned by mass percentage as follows: Si: 0.85-1.05%, Mg: 0.90-1.10%, Cu: 0.15-0.25%, Mn: 0.40-0.60%, Cr: 0.10-0.18%, Zr: 0.05-0.12%, with the balance being high-purity aluminum; Step S2, segmented homogeneous melting: High-purity aluminum is put into the melting furnace and heated to 680-695℃ to be completely melted. Si, Cu and Mn raw materials are added in sequence and stirred at a constant temperature for 15-20 minutes. Then the temperature is raised to 705-715℃ and Mg, Cr and Zr raw materials are added and stirred at a constant temperature for 25-30 minutes. The stirring speed is 280-320 r / min. 99.99% high-purity argon gas is introduced for protection throughout the melting process. Step S3, refining and removing impurities from the ingot: Add 0.3-0.5 wt% aluminum-titanium-boron refining agent to the molten aluminum, refine at a constant temperature of 710-720℃ for 12-18 min, remove surface slag and let stand for 20-25 min, then cast into cylindrical aluminum ingots using a semi-continuous casting process at a casting speed of 80-90 mm / min and a cooling water temperature of 22-28℃; Step S4, two-stage homogenization heat treatment: The aluminum casting rod is fed into a homogenization furnace. In the first stage, the temperature is raised to 480-490℃ and held for 3.5-4.5 hours. In the second stage, the temperature is raised to 510-520℃ and held for 2.5-3.5 hours. Then, it is cooled in the furnace to 320-340℃ and then removed from the furnace and air-cooled to room temperature. Step S5, Gradient temperature controlled extrusion: The cooled aluminum cast rod, extrusion cylinder, and forming die are preheated separately. The preheating temperature of the cast rod is 420-435℃, the preheating temperature of the extrusion cylinder is 410-420℃, and the preheating temperature of the die is 430-440℃. The extrusion is performed using an 1800-2000T extrusion press at an extrusion speed of 4.5-5.5m / min and an extrusion pressure of 38-42MPa to obtain the billet of the vehicle load-bearing component. Step S6, multi-stage online quenching: The billet immediately enters the gradient cooling quenching zone after extrusion. The first stage uses high-pressure water mist cooling with a cooling rate of 25-30℃ / s and a cooling time of 8-12s. The second stage uses air cooling with a cooling rate of 8-12℃ / s and a cooling time of 25-35s, so that the billet temperature is uniformly reduced to 140-160℃. Step S7, finishing and straightening treatment: The quenched billet is tension straightened, the straightening stretch is controlled at 1.2 to 1.8‰, the straightening speed is 2 to 3 m / min, and then it is sawed and deburred according to the preset size to obtain a regular component semi-finished product. Step S8, prestressed aging strengthening: The semi-finished component is loaded into the aging furnace and a segmented aging process is adopted. The first stage is held at 165-175℃ for 2-3 hours, and the second stage is held at 185-195℃ for 4-5 hours. After aging is completed, the component is removed from the furnace and air-cooled to room temperature. Step S9, Surface Composite Strengthening Treatment: Sandblasting, anodizing, and sealing are performed sequentially. Sandblasting uses 80-100 mesh quartz sand at a pressure of 0.4-0.5 MPa for 15-20 minutes. Anodizing uses 18-22V DC voltage for 40-50 minutes, resulting in an oxide film thickness of 18-22 μm. Sealing is done with boiling water for 25-30 minutes, ultimately yielding a deformation-resistant vehicle-mounted aluminum load-bearing component.

[0007] In a preferred embodiment of the present invention, in step S1, Fe impurities are ≤0.10%, Zn impurities are ≤0.05%, and Pb impurities are ≤0.01%, thus preventing local deformation defects caused by impurity segregation.

[0008] In a preferred embodiment of the present invention, in step S2, the heating rate of the segmented melting is controlled at 8-12℃ / min, and the gas pressure in the furnace is maintained at a slightly positive pressure of 0.02-0.03MPa throughout the process to avoid air mixing and the generation of oxidation inclusions.

[0009] In a preferred embodiment of the present invention, in step S3, the refining agent is an aluminum-titanium-boron ternary composite refining agent with a Ti content of 4.8-5.2% and a B content of 0.8-1.2%. After refining, the purity of the aluminum liquid is ≥99.92%, and the porosity inside the cast rod is ≤0.03%.

[0010] In a preferred embodiment of the present invention, in step S4, the heating rate of the two-stage homogeneous heat treatment is 5-8℃ / min, the temperature uniformity error in the furnace is ≤±2℃, and the internal component segregation and casting residual stress of the casting rod are eliminated.

[0011] In a preferred embodiment of the present invention, in step S5, the three-point alignment accuracy is strictly maintained during the extrusion molding process, the coaxiality error is ≤0.05mm, and the surface roughness Ra of the extrusion die cavity is ≤0.8μm, so as to ensure the dimensional accuracy of the component molding.

[0012] In a preferred embodiment of the present invention, in step S6, the gradient cooling quenching zone adopts a ring-shaped uniform water and air distribution structure, and the circumferential cooling temperature difference of the billet is ≤3℃, so as to avoid subsequent deformation caused by temperature difference stress.

[0013] In a preferred embodiment of the present invention, in step S7, the straightening equipment is a CNC tension straightening machine, and the straightness error of the straightened component is ≤0.1mm / m, and the flatness error is ≤0.08mm / m.

[0014] In a preferred embodiment of the present invention, in step S8, the segmented aging heating rate is 6-9℃ / min, and the wind speed in the aging furnace is constant at 0.8-1.2m / s to ensure uniform aging of the component as a whole, refine the precipitated phase, and improve the deformation resistance.

[0015] In a preferred embodiment of the present invention, in step S9, the surface roughness Ra of the component after sandblasting is controlled at 2.5-3.5 μm, the anodic oxidation electrolyte is sulfuric acid electrolyte with a concentration of 180-220 g / L and an electrolyte temperature of 18-22°C, and the oxide film density level after sealing reaches the first-class standard.

[0016] Compared with the prior art, the present invention has the following beneficial effects: 1. Significantly improved structural stability: This invention completely solves the problems of component segregation, coarse grains, and uneven structure in existing processes through precise alloy proportioning, segmented melting, and two-stage homogenization. The alloy matrix has finer and more uniform grains, and the reinforcing phase is dispersed and distributed, significantly improving the density of the matrix. This fundamentally enhances the material's resistance to plastic deformation, making the components less prone to bending, denting, or twisting under static and dynamic loads.

[0017] 2. Complete elimination of residual stress and prevention of stress relaxation deformation: This invention uses a full-process stress control process of gradient extrusion, multi-stage quenching, and segmented aging to eliminate residual stress generated in each process of casting, extrusion, quenching, and forming. Compared with existing single stress treatment processes, the stress is completely eliminated, the internal stress distribution of the component is uniform, and when subjected to long-term vehicle-mounted alternating loads and impact loads, there will be no dimensional deviation or structural deformation caused by stress relaxation, and the dimensional stability is greatly improved.

[0018] 3. Strong adaptability to working conditions and significantly extended service life: The load-bearing components prepared by this invention have high strength, high toughness and high dimensional stability, and can be adapted to the complex on-board working conditions of vehicle bumps, start-stop impacts and alternating torsion for a long time. They have excellent resistance to fatigue deformation and impact deformation. Compared with traditional products, the service life is increased by more than 40%, which can effectively avoid the problem of frequent deformation failure and replacement of on-board load-bearing components, and reduce vehicle use costs and safety hazards.

[0019] 4. High process controllability and good consistency in mass production: The entire process of this invention adopts precise parameter control, and the temperature, speed, pressure and time parameters of each step are precisely controllable. It abandons the existing extensive processing mode, and the product has high forming accuracy and good performance consistency. The finished product qualification rate can reach more than 99%, which is suitable for the needs of industrial mass production and has extremely high engineering application value and market promotion prospects.

[0020] 5. Synergistic effect of surface protection and structural reinforcement: Through composite surface strengthening process, a dense and hard protective layer is constructed, which not only improves the wear resistance and corrosion resistance of the component surface, but also helps to improve the strength of the surface structure, avoids local deformation caused by weakening of the surface structure, and achieves dual protection of internal structure stability and surface reinforcement, further improving the deformation resistance reliability of the component for long-term use. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments or prior art, the drawings used in the description of the embodiments or prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This invention provides a structural schematic diagram of a deformation-resistant vehicle-mounted aluminum load-bearing component.

[0023] Figure 2 This invention provides a flowchart of a method for preparing a deformation-resistant vehicle-mounted aluminum load-bearing component.

[0024] Figure 3 The temperature change curve of the segmented homogeneous melting process provided in the embodiment of the present invention is shown.

[0025] Figure 4 This is a schematic diagram illustrating the variation of the multi-stage online quenching cooling rate provided in an embodiment of the present invention.

[0026] Figure 5 The segmented aging temperature insulation curve provided for embodiments of the present invention. Detailed Implementation

[0027] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0028] like Figure 1 As shown, this embodiment of the invention provides a deformation-resistant vehicle-mounted aluminum load-bearing component. The component is a rectangular hollow profile with two parallel reinforcing ribs arranged vertically inside the cavity. The outer contour of the component is a rounded rectangle with no splicing welds or assembly gaps, thus avoiding the potential deformation hazards caused by welding stress concentration. It is suitable for vehicle chassis, vehicle equipment bases, and luggage main beam load-bearing conditions.

[0029] The core of this invention is the construction of a highly stable alloy matrix through precise alloy proportioning, coupled with a full-process gradient temperature control and graded stress relief process. This improves the deformation resistance of components by addressing aspects such as composition, microstructure, residual stress, and surface strength. The synergistic effect of each process solves the technical problem of easy deformation in existing components. Specifically, as... Figure 2 As shown, this embodiment of the invention provides a method for preparing the above-mentioned deformation-resistant vehicle-mounted aluminum load-bearing component, comprising the following steps: Step S1, alloy raw material proportioning: the raw materials are proportioned by mass percentage as follows: Si: 0.85-1.05%, Mg: 0.90-1.10%, Cu: 0.15-0.25%, Mn: 0.40-0.60%, Cr: 0.10-0.18%, Zr: 0.05-0.12%, with the balance being high-purity aluminum. The purity of each raw material is ≥99.95%.

[0030] Step S2, segmented homogeneous melting: High-purity aluminum is added to the melting furnace and heated to 680–695℃ until completely melted. Si, Cu, and Mn raw materials are added sequentially, and the mixture is stirred at a constant temperature for 15–20 minutes. Then, the temperature is raised to 705–715℃, and Mg, Cr, and Zr raw materials are added. The mixture is stirred at a constant temperature for 25–30 minutes, with a stirring speed of 280–320 r / min. 99.99% high-purity argon gas is used for protection throughout the melting process. (Reference) Figure 3 .

[0031] Step S3, refining and removing impurities from the ingot: Add 0.3-0.5 wt% aluminum-titanium-boron refining agent to the molten aluminum, refine at a constant temperature of 710-720℃ for 12-18 minutes, remove surface slag and let stand for 20-25 minutes, then cast into cylindrical aluminum ingots using a semi-continuous casting process at a casting speed of 80-90 mm / min and a cooling water temperature of 22-28℃.

[0032] Step S4, two-stage homogenization heat treatment: The aluminum casting rod is fed into a homogenization furnace. In the first stage, the temperature is raised to 480-490℃ and held for 3.5-4.5 hours. In the second stage, the temperature is raised to 510-520℃ and held for 2.5-3.5 hours. Then, it is cooled in the furnace to 320-340℃ and then removed from the furnace and air-cooled to room temperature.

[0033] Step S5, Gradient temperature controlled extrusion: The cooled aluminum cast rod, extrusion cylinder, and forming die are preheated separately. The preheating temperature of the cast rod is 420-435℃, the preheating temperature of the extrusion cylinder is 410-420℃, and the preheating temperature of the die is 430-440℃. The extrusion is performed using an 1800-2000T extrusion press with an extrusion speed of 4.5-5.5m / min and an extrusion pressure of 38-42MPa to obtain the billet of the vehicle load-bearing component.

[0034] Step S6, Multi-stage Online Quenching: Immediately after extrusion, the billet enters the gradient cooling quenching zone. The first stage uses high-pressure water mist cooling at a rate of 25–30℃ / s for 8–12 seconds. The second stage uses air cooling at a rate of 8–12℃ / s for 25–35 seconds, uniformly reducing the billet temperature to 140–160℃. (Reference) Figure 4 .

[0035] Step S7, finishing and straightening treatment: The quenched billet is tension straightened, with the straightening stretch controlled at 1.2 to 1.8‰ and the straightening speed at 2 to 3 m / min. Then, it is sawed and deburred according to the preset size to obtain a regular component semi-finished product.

[0036] Step S8, Prestressed Aging Strengthening: The semi-finished component is loaded into an aging furnace and subjected to a segmented aging process. The first stage is held at 165–175℃ for 2–3 hours, and the second stage is held at 185–195℃ for 4–5 hours. After aging, the component is removed from the furnace and air-cooled to room temperature. (Reference) Figure 5 .

[0037] Step S9, Surface composite strengthening treatment: Sandblasting, anodizing, and sealing are performed sequentially. Sandblasting uses 80-100 mesh quartz sand, with a sandblasting pressure of 0.4-0.5 MPa and a sandblasting time of 15-20 min. Anodizing uses 18-22V DC voltage, with an oxidation time of 40-50 min and an oxide film thickness of 18-22 μm. Sealing is done with boiling water for 25-30 min, finally obtaining a deformation-resistant vehicle-mounted aluminum load-bearing component.

[0038] In step S1, the raw material ratio is strictly controlled to ensure the impurity content is within ≤0.10% for Fe impurities, ≤0.05% for Zn impurities, and ≤0.01% for Pb impurities, in order to prevent local deformation defects caused by impurity agglomeration.

[0039] Step S1, the alloy raw material ratio, lays the foundation for its resistance to deformation. This invention limits the core ratio to Si: 0.85–1.05% and Mg: 0.90–1.10%. Si and Mg can form a uniformly distributed Mg2Si strengthening phase, significantly improving the strength and resistance to plastic deformation of the alloy matrix. Mn: 0.40–0.60% refines the as-cast grains, inhibits coarse grain growth, and improves the overall structural uniformity of the component. Trace elements Cr and Zr refine the grains, inhibit recrystallization, and reduce microstructural distortion during high-temperature processing. Strictly limiting the content of various impurities avoids impurity agglomeration and the formation of stress concentration points, eliminating local deformation defects under stress. Compared to existing coarse-ratio processes, the stability and mechanical uniformity of the alloy composition are significantly improved.

[0040] In step S2, the heating rate of the segmented melting is controlled at 8-12℃ / min, and the gas pressure in the furnace is maintained at a slightly positive pressure of 0.02-0.03MPa throughout the process to avoid air mixing and the generation of oxidation inclusions.

[0041] Step S2, segmented homogeneous melting, specifically addresses the compositional segregation problem caused by one-time melting. Based on the differences in melting points of each element, melting is performed in segments: high-melting-point elements like Si, Cu, and Mn are melted and diffused first, while low-melting-point elements like Mg, Cr, and Zr are added later. This avoids the problem of low-melting-point elements burning off at high temperatures and high-melting-point elements not melting completely. Combined with constant-speed stirring and argon gas micro-positive pressure protection, this ensures uniform mixing of the alloy components, free of oxide inclusions, eliminating the potential for localized deformation caused by compositional inhomogeneity. Precise control of the segmented heating rate prevents sudden temperature changes from disrupting the alloy's microstructure, ensuring a uniform and stable matrix structure.

[0042] In step S3, the refining agent is an aluminum-titanium-boron ternary composite refining agent with a Ti content of 4.8-5.2% and a B content of 0.8-1.2%. After refining, the purity of the aluminum liquid is ≥99.92%, and the porosity inside the cast rod is ≤0.03%.

[0043] Step S3, refining and impurity removal of the ingot, further purifies the alloy matrix. A customized aluminum-titanium-boron composite refining agent is used, which can efficiently adsorb impurities such as oxide slag and pores in the aluminum melt, reduce the porosity and inclusion defects of the ingot, and improve the density of the matrix. Precise control of casting speed and cooling water temperature ensures uniform grain growth in the ingot, free from casting defects, avoids stress deformation caused by matrix defects, and improves the overall load-bearing uniformity of the component.

[0044] In step S4, the heating rate of the two-stage homogeneous heat treatment is 5-8℃ / min, the temperature uniformity error in the furnace is ≤±2℃, and the internal component segregation and casting residual stress of the casting rod are eliminated.

[0045] Step S4, the two-stage homogenization heat treatment, is crucial for eliminating residual casting stress and refining grain size. The first stage, low-temperature holding, eliminates micro-segregation within the cast ingot, while the second stage, high-temperature holding, promotes thorough grain refinement and homogenization. The slow cooling mode in the furnace avoids the generation of new stresses from rapid cooling. Compared to existing single-stage homogenization processes, this method can completely eliminate residual casting stress, regulate the grain structure, and significantly improve the matrix's resistance to deformation.

[0046] In step S5, during the extrusion molding process, the three points must be aligned in a straight line with a coaxiality error of ≤0.05mm and the surface roughness Ra of the extrusion die cavity must be ≤0.8μm to ensure the dimensional accuracy of the formed component.

[0047] Step S5, gradient temperature-controlled extrusion, achieves uniform metal flow and reduces molding stress. Precise matching of the gradient preheating temperatures of the casting rod, extrusion cylinder, and die ensures optimal plastic flow of the metal. Combined with constant extrusion speed and pressure, and strict control of alignment accuracy and die flatness, this ensures uniform and turbulent metal flow during extrusion molding, preventing localized accumulation and distortion, effectively reducing residual stress generated during extrusion molding, and guaranteeing dimensional accuracy and uniform microstructure of the formed components.

[0048] In step S6, the gradient cooling quenching zone adopts a ring-shaped uniform water and air distribution structure, and the circumferential cooling temperature difference of the billet is ≤3℃ to avoid subsequent deformation caused by thermal stress.

[0049] Step S6, multi-stage online quenching, achieves stable stress release and stable phase transformation. A gradient quenching mode, employing rapid water mist cooling followed by slow air cooling, allows for precise control of the cooling rate compared to a single quenching process. This avoids quenching stress caused by excessive internal and external temperature differences due to rapid cooling, while ensuring sufficient and uniform phase transformation of the alloy, forming a stable supersaturated solid solution. This provides a good microstructure foundation for subsequent aging strengthening and prevents later deformation caused by residual quenching stress.

[0050] In step S7, the straightening equipment is a CNC tension straightening machine. After straightening, the straightness error of the component is ≤0.1mm / m and the flatness error is ≤0.08mm / m.

[0051] Step S7, fine straightening, ensures the forming accuracy and flatness of the component. Precise tension straightening controls minute stretching amounts, correcting slight bending and warping deformations generated during quenching and extrusion, strictly controlling straightness and flatness errors, removing burrs and sharp edges from the component surface, avoiding stress concentration during subsequent use, and ensuring assembly accuracy and uniform stress distribution.

[0052] In step S8, the segmented aging heating rate is 6-9℃ / min, and the air velocity in the aging furnace is kept constant at 0.8-1.2m / s to ensure uniform aging of the component as a whole, refine the precipitated phase, and improve the deformation resistance.

[0053] Step S8, prestressed segmented aging strengthening, is the core process for improving resistance to stress relaxation deformation. The two-stage gradient aging process initially precipitates fine and dispersed strengthening phases at low temperature, and promotes the uniform growth and regular distribution of strengthening phases at high temperature, completely eliminating various residual stresses left over from previous processing. This significantly improves the structural stability and stress relaxation resistance of the alloy matrix, solving the problems of disordered precipitates and incomplete stress elimination in existing single aging processes, making the component less prone to deformation when subjected to long-term dynamic loads.

[0054] In step S9, the surface roughness Ra of the component after sandblasting is controlled at 2.5–3.5 μm. The anodic oxidation electrolyte is sulfuric acid electrolyte with a concentration of 180–220 g / L and an electrolyte temperature of 18–22 °C. After sealing, the oxide film density reaches the first-class standard. Step S9 involves surface composite strengthening treatment to construct a protective and reinforcing layer. Precision sandblasting optimizes the surface roughness of the component and enhances the adhesion of the oxide film; controlled anodizing forms a dense and uniform hard oxide film, improving the component's surface resistance to impact, wear, and deformation; boiling water sealing seals the micropores of the oxide film, further enhancing the surface density and stability, preventing local structural weakening caused by surface wear and corrosion, and indirectly improving the overall deformation resistance and durability of the component.

[0055] Example 1 A method for manufacturing a deformation-resistant vehicle-mounted aluminum load-bearing component includes the following steps: Step S1, alloy raw material ratio: according to mass percentage, Si: 0.95%, Mg: 1.00%, Cu: 0.20%, Mn: 0.50%, Cr: 0.14%, Zr: 0.08%, impurities Fe≤0.10%, Zn≤0.05%, Pb≤0.01%, balance is 99.95% high-purity aluminum; Step S2, segmented homogeneous melting: High-purity aluminum is put into the melting furnace and heated to 690℃ at 10℃ / min until completely melted. Si, Cu and Mn raw materials are added in sequence and stirred at 300r / min for 18min. Then, the temperature is raised to 710℃ at 10℃ / min and Mg, Cr and Zr raw materials are added and stirred at 300r / min for 28min. 99.99% high-purity argon gas is introduced throughout the process, and the furnace is maintained at a slight positive pressure of 0.025MPa. Step S3, refining and removing impurities from the ingot: Add 0.4wt% aluminum-titanium-boron refining agent (Ti content 5.0%, B content 1.0%), refine at a constant temperature of 715℃ for 15min, skim off the slag and let stand for 22min, cast the ingot using a semi-continuous casting process, casting speed 85mm / min, cooling water temperature 25℃. Step S4, two-stage homogenization heat treatment: the cast rod is fed into a homogenization furnace, heated to 485°C at 6°C / min and held for 4 hours, then heated to 515°C and held for 3 hours, and then cooled to 330°C in the furnace before being taken out and air-cooled to room temperature. Step S5, gradient temperature-controlled extrusion: preheat the casting rod to 428℃, the extrusion cylinder to 415℃, and the die to 435℃. Use a 1900T extruder, extrusion speed 5.0m / min, extrusion pressure 40MPa, centering coaxiality error ≤0.05mm, die cavity roughness Ra≤0.8μm, and extrusion molding to obtain component blank; Step S6, multi-stage online quenching: After the billet is extruded, it is first cooled by high-pressure water mist at a cooling rate of 28℃ / s for 10s, and then cooled by air cooling at a cooling rate of 10℃ / s for 30s, cooling down to 150℃, with a circumferential cooling temperature difference of ≤3℃. Step S7, finishing and straightening: A CNC tension straightening machine is used with a tension of 1.5‰ and a straightening speed of 2.5m / min. After straightening, the straightness is ≤0.1mm / m and the flatness is ≤0.08mm / m. Then, sawing and deburring are performed. Step S8, prestressed aging strengthening: heat up at 7℃ / min, hold at 170℃ for 2.5h, then heat up to 190℃ and hold for 4.5h, with an air velocity of 1.0m / s in the furnace, and air cool to room temperature after aging is completed; Step S9, Surface composite strengthening treatment: 90-mesh quartz sand is used for sandblasting at 0.45MPa pressure for 18 minutes, and the surface roughness Ra is controlled at 3.0μm; anodizing is carried out under constant temperature conditions of 20℃, 20V DC voltage, 200g / L sulfuric acid electrolyte, for 45 minutes, and the oxide film thickness is 20μm; boiling water sealing is carried out for 28 minutes to complete the component preparation.

[0056] Example 2 A method for manufacturing a deformation-resistant vehicle-mounted aluminum load-bearing component includes the following steps: Step S1, alloy raw material ratio: by mass percentage, Si: 0.85%, Mg: 0.90%, Cu: 0.15%, Mn: 0.40%, Cr: 0.10%, Zr: 0.05%, impurities Fe≤0.10%, Zn≤0.05%, Pb≤0.01%, balance is 99.95% high-purity aluminum; Step S2, segmented homogeneous melting: High-purity aluminum is put into the melting furnace and heated to 680°C at 8°C / min until completely melted. Si, Cu and Mn raw materials are added in sequence and stirred at a constant temperature of 280 r / min for 15 min. Then, the temperature is raised to 705°C at 8°C / min and Mg, Cr and Zr raw materials are added and stirred at a constant temperature of 280 r / min for 25 min. 99.99% high-purity argon gas is introduced throughout the process, and a slight positive pressure of 0.02 MPa is maintained in the furnace. Step S3, refining and removing impurities from the ingot: add 0.3wt% aluminum-titanium-boron refining agent, refine at a constant temperature of 710℃ for 12min, skim off the slag and let stand for 20min, casting speed 80mm / min, cooling water temperature 22℃; Step S4, two-stage homogenization heat treatment: heat up to 480℃ at 5℃ / min and hold for 3.5h, then heat up to 510℃ and hold for 2.5h, then cool in the furnace to 320℃ and air cool after removal from the furnace. Step S5, gradient temperature-controlled extrusion: preheating of the casting rod to 420℃, extrusion cylinder to 410℃, and die to 430℃; 1800T extrusion press, extrusion speed 4.5m / min, extrusion pressure 38MPa; Step S6, multi-stage online quenching: water mist cooling rate 25℃ / s, duration 8s, air cooling rate 8℃ / s, duration 25s, cooling down to 140℃; Step S7, finishing and straightening treatment: stretching amount 1.2‰, straightening speed 2m / min, to complete straightening, sawing and deburring; Step S8, prestressed aging strengthening: heat up at 6℃ / min, hold at 165℃ for 2h, hold at 185℃ for 4h, and the wind speed inside the furnace is 0.8m / s; Step S9, surface composite strengthening treatment: 80 mesh quartz sand, 0.4MPa sandblasting for 15min, 18V voltage anodizing for 40min, oxide film 18μm, boiling water sealing for 25min, to obtain the finished component.

[0057] Comparative example (existing conventional process) The existing traditional manufacturing process for vehicle-mounted aluminum load-bearing components is adopted: conventional 6063 aluminum alloy general proportion, one-time integral melting, single homogenization heat preservation at 480℃ for 3 hours, non-gradient temperature controlled extrusion, single water cooling quenching, constant temperature aging at 180℃ for 4 hours, conventional sandblasting anodizing treatment, and the remaining processing flow is consistent with the embodiment of the present invention.

[0058] Performance test results: The mechanical properties and deformation resistance of the vehicle-mounted aluminum load-bearing components prepared in Examples 1-2 and the comparative example of this invention were tested according to the testing standards of the automotive aluminum alloy component industry. The results are as follows: The components prepared in Examples 1-2 of this invention have a tensile strength ≥385MPa, a yield strength ≥340MPa, and an elongation after fracture ≥12.5%; after 100,000 cycles of vehicle-mounted alternating load fatigue test, the deformation of the component is ≤0.02mm, with no stress relaxation or bending deformation; the component in the comparative example has a tensile strength of only 310MPa, a yield strength of 275MPa, and a deformation of 0.18mm after 100,000 fatigue tests, showing obvious bending deformation and dimensional deviation. Therefore, it can be seen that the deformation resistance and mechanical stability of the components prepared by the process of this invention are far superior to those prepared by existing conventional processes, solving the technical problem of easy deformation of existing components under long-term working conditions.

[0059] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely preferred examples and are not intended to limit the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a deformation-resistant vehicle-mounted aluminum load-bearing component, characterized in that, Includes the following steps: Step S1, alloy raw material proportioning: the raw materials are proportioned by mass percentage as follows: Si: 0.85-1.05%, Mg: 0.90-1.10%, Cu: 0.15-0.25%, Mn: 0.40-0.60%, Cr: 0.10-0.18%, Zr: 0.05-0.12%, with the balance being high-purity aluminum; Step S2, segmented homogeneous melting: High-purity aluminum is put into the melting furnace and heated to 680-695℃ to be completely melted. Si, Cu and Mn raw materials are added in sequence and stirred at a constant temperature for 15-20 minutes. Then the temperature is raised to 705-715℃ and Mg, Cr and Zr raw materials are added and stirred at a constant temperature for 25-30 minutes. The stirring speed is 280-320 r / min. 99.99% high-purity argon gas is introduced for protection throughout the melting process. Step S3, refining and removing impurities from the ingot: Add 0.3-0.5 wt% aluminum-titanium-boron refining agent to the molten aluminum, refine at a constant temperature of 710-720℃ for 12-18 min, remove surface slag and let stand for 20-25 min, then cast into cylindrical aluminum ingots using a semi-continuous casting process at a casting speed of 80-90 mm / min and a cooling water temperature of 22-28℃; Step S4, two-stage homogenization heat treatment: The aluminum casting rod is fed into a homogenization furnace. In the first stage, the temperature is raised to 480-490℃ and held for 3.5-4.5 hours. In the second stage, the temperature is raised to 510-520℃ and held for 2.5-3.5 hours. Then, it is cooled in the furnace to 320-340℃ and then removed from the furnace and air-cooled to room temperature. Step S5, Gradient temperature controlled extrusion: The cooled aluminum cast rod, extrusion cylinder, and forming die are preheated separately. The preheating temperature of the cast rod is 420-435℃, the preheating temperature of the extrusion cylinder is 410-420℃, and the preheating temperature of the die is 430-440℃. The extrusion is performed using an 1800-2000T extrusion press with an extrusion speed of 4.5-5.5m / min and an extrusion pressure of 38-42MPa to obtain the billet of the vehicle load-bearing component. Step S6, multi-stage online quenching: The billet immediately enters the gradient cooling quenching zone after extrusion. The first stage uses high-pressure water mist cooling with a cooling rate of 25-30℃ / s and a cooling time of 8-12s. The second stage uses air cooling with a cooling rate of 8-12℃ / s and a cooling time of 25-35s, so that the billet temperature is uniformly reduced to 140-160℃. Step S7, finishing and straightening treatment: The quenched billet is tension straightened, the straightening stretch is controlled at 1.2 to 1.8‰, the straightening speed is 2 to 3 m / min, and then it is sawed and deburred according to the preset size to obtain a regular component semi-finished product. Step S8, prestressed aging strengthening: The semi-finished component is loaded into the aging furnace and a segmented aging process is adopted. The first stage is held at 165-175℃ for 2-3 hours, and the second stage is held at 185-195℃ for 4-5 hours. After aging is completed, the component is removed from the furnace and air-cooled to room temperature. Step S9, Surface Composite Strengthening Treatment: Sandblasting, anodizing, and sealing are performed sequentially. Sandblasting uses 80-100 mesh quartz sand at a pressure of 0.4-0.5 MPa for 15-20 minutes. Anodizing uses 18-22V DC voltage for 40-50 minutes, resulting in an oxide film thickness of 18-22 μm. Sealing is done with boiling water for 25-30 minutes, ultimately yielding a deformation-resistant vehicle-mounted aluminum load-bearing component.

2. The method for preparing the deformation-resistant vehicle-mounted aluminum load-bearing component according to claim 1, characterized in that, In step S1, Fe impurities are ≤0.10%, Zn impurities are ≤0.05%, and Pb impurities are ≤0.01% to prevent local deformation defects caused by impurity segregation.

3. The method for preparing the deformation-resistant vehicle-mounted aluminum load-bearing component according to claim 2, characterized in that, In step S2, the heating rate of the segmented melting is controlled at 8-12℃ / min, and the gas pressure in the furnace is maintained at a slightly positive pressure of 0.02-0.03MPa throughout the process to avoid air mixing and the generation of oxidation inclusions.

4. The method for preparing the deformation-resistant vehicle-mounted aluminum load-bearing component according to claim 3, characterized in that, In step S3, the refining agent is an aluminum-titanium-boron ternary composite refining agent with a Ti content of 4.8-5.2% and a B content of 0.8-1.2%. After refining, the purity of the aluminum liquid is ≥99.92%, and the porosity inside the cast rod is ≤0.03%.

5. The method for preparing the deformation-resistant vehicle-mounted aluminum load-bearing component according to claim 4, characterized in that, In step S4, the heating rate of the two-stage homogeneous heat treatment is 5-8℃ / min, the temperature uniformity error in the furnace is ≤±2℃, and the internal component segregation and casting residual stress of the casting rod are eliminated.

6. The method for preparing the deformation-resistant vehicle-mounted aluminum load-bearing component according to claim 1, characterized in that, In step S5, during the extrusion molding process, the three points must be aligned in a straight line with a coaxiality error of ≤0.05mm and the surface roughness Ra of the extrusion die cavity must be ≤0.8μm to ensure the dimensional accuracy of the formed component.

7. The method for preparing the deformation-resistant vehicle-mounted aluminum load-bearing component according to claim 1, characterized in that, In step S6, the gradient cooling quenching zone adopts a ring-shaped uniform water and air distribution structure, and the circumferential cooling temperature difference of the billet is ≤3℃ to avoid subsequent deformation caused by thermal stress.

8. The method for preparing the deformation-resistant vehicle-mounted aluminum load-bearing component according to claim 1, characterized in that, In step S7, the straightening equipment is a CNC tension straightening machine. After straightening, the straightness error of the component is ≤0.1mm / m and the flatness error is ≤0.08mm / m.

9. The method for preparing the deformation-resistant vehicle-mounted aluminum load-bearing component according to claim 1, characterized in that, In step S8, the segmented aging heating rate is 6-9℃ / min, and the air velocity in the aging furnace is kept constant at 0.8-1.2m / s to ensure uniform aging of the component as a whole, refine the precipitated phase, and improve the deformation resistance.

10. The method for preparing the deformation-resistant vehicle-mounted aluminum load-bearing component according to claim 1, characterized in that, In step S9, the surface roughness Ra of the component after sandblasting is controlled at 2.5-3.5 μm, the anodic oxidation electrolyte is sulfuric acid electrolyte with a concentration of 180-220 g / L and an electrolyte temperature of 18-22℃, and the oxide film density level after sealing reaches the first-class standard.

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