Automobile aluminum alloy component with excellent fracture toughness and preparation method thereof

Abstract

The invention discloses an automobile aluminum alloy component with excellent fracture toughness and a preparation method thereof. Components of the component aluminum alloy contain elements such as silicon, magnesium, copper, manganese and titanium, and the strength and toughness are improved through scientific proportioning. The cross section of the sectional material is of a rectangular frame structure, and the transverse ribs, the ring-shaped pieces, the X-shaped reinforcing ribs, the arc-shaped pieces and the connecting ribs are arranged and cooperate to disperse stress, so that the overall stability is enhanced. The preparation method comprises the steps of smelting, casting, homogenization treatment, extrusion forming, solid solution and aging treatment and the like, uniform and pure components are guaranteed through smelting, a structure is formed through casting and extrusion forming, a microstructure is optimized through solid solution and aging treatment, and a strengthening phase is separated out. Through cooperation of multiple processes, the fracture toughness of the manufactured component is remarkably improved, the requirements of the automobile industry for high-performance aluminum alloy components are met, and the safety and reliability of automobiles are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of automobile parts manufacturing, and in particular to an automobile aluminum alloy component with excellent fracture toughness and a preparation method thereof. Background Art

[0002] In the automotive industry, aluminum alloy components are widely used in various parts of automobiles, such as body frames and chassis components, due to their advantages such as light weight and high strength. As the automotive industry's requirements for safety and reliability continue to increase, higher requirements are placed on the fracture toughness of aluminum alloy components. At present, existing automotive aluminum alloy components have certain deficiencies in fracture toughness, and their structural design and preparation processes are difficult to meet the growing performance requirements. For example, the structural design of some aluminum alloy components is unreasonable, which makes them prone to fracture when subjected to external force impact; at the same time, the existing preparation process has defects in alloy composition control, forming process, etc., and cannot effectively improve the fracture toughness of aluminum alloy components. Therefore, there is an urgent need to develop an automotive aluminum alloy component with excellent fracture toughness and a preparation method thereof to meet the development needs of the automotive industry. Summary of the Invention

[0003] In order to solve the technical problems existing in the background technology, the present invention provides an automotive aluminum alloy component with excellent fracture toughness and a preparation method thereof.

[0004] The present invention provides an automotive aluminum alloy component with excellent fracture toughness. The aluminum alloy components include, by mass percentage, 1.2-1.8% silicon (Si), 0.8-1.5% magnesium (Mg), 0.3-0.8% copper (Cu), 0.2-0.5% manganese (Mn), 0.05-0.15% titanium (Ti), and the balance being aluminum (Al) and unavoidable impurities.

[0005] The cross section of the profile is a rectangular frame structure, and the rectangular frame extends along the long side direction; a transverse rib is provided between the midpoints of the two short sides of the rectangular frame, and the transverse rib is parallel to the long side of the rectangular frame and has its two ends fixedly connected to the midpoints of the short sides of the rectangular frame;

[0006] The transverse ribs are provided with a plurality of equally spaced ring-shaped parts, and the transverse ribs divide each of the ring-shaped parts into two equal halves;

[0007] An X-shaped reinforcement rib is provided in the inner ring of each of the ring-shaped members, and the X-shaped reinforcement rib cooperates with the transverse rib to divide the ring-shaped member into 6 equal parts;

[0008] The X-shaped reinforcement rib has four extensions extending out of the ring-shaped member, the four extensions are respectively connected to the long sides of the rectangular frame, and there is a certain distance between the connection points of every two adjacent extensions and the long sides of the rectangular frame;

[0009] Every two adjacent ring-shaped parts are connected by two arc-shaped parts. The two arc-shaped parts are symmetrically distributed with the transverse rib as the symmetry axis, and the curvature of the two arc-shaped parts is convex toward the direction close to the transverse rib.

[0010] Preferably, a connecting rib is connected between the midpoint of each arc-shaped member and the adjacent long side of the rectangular frame, and the connecting rib is perpendicular to the long side connected to the rectangular frame.

[0011] Preferably, the four extensions of the X-shaped reinforcement ribs are connected to the long sides of the rectangular frame by welding or riveting.

[0012] Preferably, the arc-shaped member is connected to the ring-shaped member and the rectangular frame by integral molding or welding.

[0013] Preferably, the steps include:

[0014] Melting: Pure aluminum and various alloying elements are added to a melting furnace according to the proportion of aluminum alloy components. The temperature is raised to 720-760°C for melting. After the raw materials are completely melted, they are stirred for 15-25 minutes. A refining agent accounting for 0.1-0.3% of the melt mass is added to the melt. The melt is refined at 720-740°C for 20-30 minutes. After refining, the melt is allowed to stand for 10-15 minutes and the surface scum is removed. The aluminum alloy components include, by mass percentage, 1.2-1.8% silicon (Si), 0.8-1.5% magnesium (Mg), 0.3-0.8% copper (Cu), 0.2-0.5% manganese (Mn), 0.05-0.15% titanium (Ti), and the balance is aluminum (Al) and unavoidable impurities.

[0015] Casting: The refined aluminum alloy melt temperature is controlled at 680-720℃, and the melt is poured into a water-cooled crystallizer using a semi-continuous casting process. The casting speed is controlled at 60-80mm / min, and the cooling water flow rate is 8-12L / min to obtain an aluminum alloy ingot;

[0016] Homogenization treatment: heat the aluminum alloy ingot to 480-520℃, keep it at this temperature for 8-12 hours, and then cool it to room temperature with the furnace;

[0017] Extrusion molding: heating the homogenized ingot to 420-460° C., placing it in an extruder, and extruding it according to the profile structure of claim 1, with the extrusion speed controlled at 3-5 mm / s and the extrusion ratio at 20-30, to obtain a preliminarily formed aluminum alloy profile;

[0018] Solution treatment: Heat the extruded aluminum alloy profile to 500-540℃, keep it warm for 1-2 hours, then quickly put it into a water tank with a water temperature of 20-30℃ for water cooling quenching, with a cooling rate of not less than 50℃ / s;

[0019] Aging treatment: Place the aluminum alloy profile after solution treatment in an aging furnace, first age it at 120-140℃ for 6-8 hours, then raise the temperature to 160-180℃ and continue ageing for 4-6 hours;

[0020] Processing and inspection: The aluminum alloy profiles after aging treatment are mechanically processed to meet the dimensional requirements of automotive aluminum alloy components. The components are subjected to ultrasonic flaw detection, tensile testing and other tests to screen out products that meet the fracture toughness requirements.

[0021] Preferably, the refining agent is hexachloroethane, carbon tetrachloride or one or more mixtures of hexachloroethane and carbon tetrachloride.

[0022] Preferably, in the semi-continuous casting process, the inner wall of the crystallizer is coated with graphite lubricant.

[0023] The present invention provides an automotive aluminum alloy component with excellent fracture toughness and a method for preparing the same, which has the following technical effects:

[0024] Alloy composition optimization: This invention optimizes the ratios of silicon, magnesium, copper, manganese, and titanium in the aluminum alloy to optimize their synergy. Silicon and magnesium form reinforcing phases, enhancing the alloy's strength; copper and manganese optimize the alloy's heat treatment properties; and titanium refines the grain size, effectively increasing the material's toughness. This, in turn, lays the foundation for improved fracture toughness at the alloy composition level.

[0025] Unique Structural Design: The unique cross-sectional design of automotive aluminum alloy components, including the rectangular frame, transverse ribs, rings, X-shaped reinforcements, curved elements, and connecting ribs, effectively disperses stress and enhances the overall strength and stability of the components. When subjected to external forces, this structure evenly distributes stress, preventing fracture caused by stress concentration and significantly improving the component's fracture toughness.

[0026] The rectangular frame serves as the underlying structure, providing a stable overall framework for the components. Extending along its long sides, the rectangular frame conforms to the longitudinal loads that automotive components endure in actual use, effectively carrying and transmitting external forces. The transverse reinforcements located between the midpoints of the short sides, parallel to the long sides and fixed at both ends, not only enhance the lateral stability of the rectangular frame but also divide the overall structure into multiple load-bearing units. When a component is impacted by an external force, the transverse reinforcements help the rectangular frame disperse stress, preventing stress concentration in a single location within the frame. This reduces the risk of component fracture due to excessive localized stress and lays the foundation for improved fracture toughness.

[0027] The ring-shaped parts on the transverse reinforcement are distributed at equal distances and are bisected by the transverse reinforcement, which forms multiple relatively independent and interrelated structural units in the cross section of the component. The X-shaped reinforcement ribs set in each ring-shaped part cooperate with the transverse reinforcement to divide the ring-shaped part into 6 equal parts. This structural design greatly increases the structural complexity and stability of the component. When external force acts on the component, the structure composed of the ring-shaped parts and X-shaped reinforcement ribs can disperse and absorb energy from multiple directions. The four extensions of the X-shaped reinforcement ribs are connected to the long sides of the rectangular frame, further transferring the stress to the entire frame, and there is a distance between the connection points of adjacent extensions, which avoids excessive concentration of stress at the connection part, so that the stress can be evenly distributed on the entire component, effectively improving the component's ability to resist fracture.

[0028] Adjacent ring-shaped members are connected by two curved members, symmetrically centered around the transverse reinforcement and projecting toward it. This curved structure allows for a certain degree of elastic deformation when subjected to stress, thereby absorbing and buffering external forces. Furthermore, connecting ribs, perpendicularly connected at the midpoint of the curved members to the long sides of the rectangular frame, further enhance the strength and stability of the connection between the curved members and the frame. When the component is impacted, the curved members and connecting ribs work together to absorb energy through deformation while reliably transmitting force to the rectangular frame through the connecting ribs. This creates an organic whole that resists external forces, prevents the initiation and propagation of cracks, and significantly improves the component's fracture toughness.

[0029] In the preparation method of this invention, the smelting process ensures the uniformity and purity of the alloy composition; semi-continuous casting, homogenization, and extrusion molding processes impart fine microstructure and structure to the components; and solution treatment and aging treatments further optimize the alloy's microstructure, precipitating fine, dispersed strengthening phases that effectively enhance both strength and fracture toughness. Through the synergistic effect of these process steps, the resulting automotive aluminum alloy components possess excellent fracture toughness, meeting the automotive industry's demand for high-performance aluminum alloy components.

[0030] Additional aspects and advantages of the present invention will be set forth in part in the description which follows and, in part, will be obvious from the description which follows, or may be learned by practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a schematic diagram of the structure of the present invention;

[0032] Figure 2 It is a top view of the present invention.

[0033] Explanation of the numbers in the figure: 1. Rectangular frame; 2. Horizontal rib; 3. Ring-shaped part; 4. X-shaped reinforcement rib; 5. Arc-shaped part; 6. Connecting rib. DETAILED DESCRIPTION

[0034] The following describes embodiments of the present invention in detail. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar symbols throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended only to explain the present invention, and are not to be construed as limiting the present invention.

[0035] like Figure 1-Figure 2 An automotive aluminum alloy component with excellent fracture toughness is shown, and its aluminum alloy components include, by mass percentage, 1.2-1.8% silicon (Si), 0.8-1.5% magnesium (Mg), 0.3-0.8% copper (Cu), 0.2-0.5% manganese (Mn), 0.05-0.15% titanium (Ti), and the balance being aluminum (Al) and unavoidable impurities.

[0036] The cross-section of the profile is a rectangular frame 1 structure, which extends along the long side. A transverse rib 2 is provided between the midpoints of the two short sides of the rectangular frame 1. The transverse rib 2 is parallel to the long side of the rectangular frame 1 and has its ends fixedly connected to the midpoints of the short sides of the rectangular frame 1. A plurality of equally spaced ring-shaped parts 3 are provided on the transverse rib 2, which divide each ring-shaped part 3 into two halves. An X-shaped reinforcing rib 4 is provided in the inner circle of each ring-shaped part 3. The X-shaped reinforcing rib 4 cooperates with the transverse rib 2 to divide the ring-shaped part 3 into six parts. The X-shaped reinforcing rib 4 has four extensions extending from the ring-shaped part 3. The four extensions are respectively connected to the long sides of the rectangular frame 1, and there is a certain distance between each two adjacent extensions and the connection points of the long sides of the rectangular frame 1. Each two adjacent ring-shaped parts 3 are connected by two arc-shaped parts 5. The two arc-shaped parts 5 are symmetrically distributed with the transverse rib 2 as the axis of symmetry, and the curvature of the two arc-shaped parts 5 protrudes in the direction close to the transverse rib 2.

[0037] Furthermore, a connecting rib 6 connects the midpoint of each arc-shaped member 5 to the adjacent long side of the rectangular frame 1. The connecting rib 6 is perpendicular to the long side of the rectangular frame 1. The four extensions of the X-shaped reinforcing rib 4 are connected to the long side of the rectangular frame 1 by welding or riveting. The arc-shaped member 5 is connected to the ring-shaped member 3 and the rectangular frame 1 by integral molding or welding.

[0038] The present invention also provides a method for preparing an automotive aluminum alloy component with excellent fracture toughness, comprising the following steps:

[0039] Melting: Pure aluminum and the alloying elements are added to a melting furnace according to the aforementioned alloy composition ratios. The furnace is heated to 720-760°C for melting. Once the raw materials are completely melted, they are stirred for 15-25 minutes to ensure thorough mixing of the alloy components. A refining agent (hexachloroethane, carbon tetrachloride, or a mixture of hexachloroethane and carbon tetrachloride) is then added at 0.1-0.3% by weight. The melt is then refined at 720-740°C for 20-30 minutes to remove gases and inclusions. After refining, the melt is allowed to stand for 10-15 minutes, and surface scum is removed.

[0040] The melting temperature is precisely controlled at 720-760°C and stirred for 15-25 minutes to ensure that the pure aluminum and various alloying elements are fully melted and evenly mixed, so that the aluminum alloy composition precisely meets the designed proportions. A refining agent (hexachloroethane, carbon tetrachloride, etc.) is added at a rate of 0.1-0.3% of the melt mass, and the melt is refined at 720-740°C for 20-30 minutes to effectively remove gases and inclusions from the melt, reduce defects such as pores and impurities within the component, and improve the purity of the aluminum alloy, providing a good foundation for subsequent processes and component performance, avoiding stress concentration caused by impurities and gases, and thus improving fracture toughness.

[0041] Casting: The refined aluminum alloy melt is controlled at a temperature of 680-720°C and poured into a water-cooled crystallizer using a semi-continuous casting process. The casting speed is controlled at 60-80 mm / min, and the cooling water flow rate is 8-12 L / min, resulting in an aluminum alloy ingot. During the semi-continuous casting process, the inner wall of the crystallizer is coated with graphite lubricant to reduce friction between the ingot and the crystallizer, ensuring the quality of the ingot.

[0042] By controlling the aluminum alloy melt temperature at 680-720°C and employing a semi-continuous casting process, coupled with a casting speed of 60-80 mm / min and a cooling water flow rate of 8-12 L / min, the aluminum alloy melt solidifies rapidly and evenly in the water-cooled crystallizer, forming a dense ingot. A graphite lubricant is applied to the inner wall of the crystallizer to reduce friction between the ingot and the mold, preventing cracks and defects on the ingot surface. This ensures the quality of the ingot and provides high-quality billet for subsequent processing. Good ingot quality contributes to improved overall performance and fracture toughness of the final component.

[0043] Homogenization treatment: Heat the aluminum alloy ingot to 480-520℃ and keep it warm for 8-12 hours to eliminate the component segregation inside the ingot and make the alloy structure homogenized, and then cool it to room temperature with the furnace.

[0044] The ingot is heated to 480-520°C and held for 8-12 hours to eliminate internal component segregation caused by the casting process and achieve uniform alloy structure. This uniform structure ensures stable and consistent performance across all parts of the component during subsequent processing and use, avoiding weak spots caused by local composition differences, thereby improving the overall strength and fracture toughness of the component.

[0045] Extrusion molding: The homogenized ingot is heated to 420-460°C, placed in an extruder, and extruded according to the profile structure of the above-mentioned automotive aluminum alloy component. The extrusion speed is controlled at 3-5 mm / s and the extrusion ratio is 20-30 to obtain a preliminarily formed aluminum alloy profile.

[0046] The homogenized ingot is heated to 420-460°C for extrusion molding. This temperature range imparts excellent plasticity to the aluminum alloy, facilitating the molding of complex profiles according to the design. An extrusion speed of 3-5 mm / s and an extrusion ratio of 20-30 ensure that the aluminum alloy fully fills the mold, resulting in a profile with precise dimensions and a complete shape. Furthermore, the plastic deformation during the extrusion process refines the grain size, further improving the strength and toughness of the profile, making the component less susceptible to fracture when subjected to external forces.

[0047] Solution treatment: Heat the extruded aluminum alloy profile to 500-540℃ and keep it warm for 1-2 hours to allow the alloy elements to fully dissolve in the aluminum matrix. Then quickly place it in a water tank with a water temperature of 20-30℃ for water quenching. The cooling rate should be no less than 50℃ / s to obtain a supersaturated solid solution.

[0048] Aging treatment: Place the aluminum alloy profile after solution treatment in an aging furnace, first age it at 120-140℃ for 6-8 hours, then raise the temperature to 160-180℃ and continue ageing for 4-6 hours. The aging treatment allows fine and dispersed strengthening phases to precipitate in the aluminum alloy, thereby increasing the strength and further improving the fracture toughness.

[0049] During solution treatment, the profile is heated to 500-540°C, held for 1-2 hours, and then rapidly water-quenched to fully dissolve the alloying elements in the aluminum matrix, forming a supersaturated solid solution. The subsequent aging treatment, initially at 120-140°C for 6-8 hours, then raised to 160-180°C for another 4-6 hours, promotes the precipitation of fine, dispersed strengthening phases in the aluminum alloy. These strengthening phases are evenly distributed in the aluminum matrix, enhancing component strength while hindering dislocation motion and suppressing crack initiation and propagation, thereby significantly improving the component's fracture toughness.

[0050] Processing and Inspection: After aging treatment, the aluminum alloy profiles are machined to meet the dimensional requirements of automotive aluminum alloy components. Finally, the components are subjected to ultrasonic testing, tensile testing, and other tests to select products that meet the fracture toughness requirements.

[0051] Machining ensures that components achieve precise dimensional requirements, meeting the assembly and operational demands of automotive parts. Rigorous testing methods, such as ultrasonic flaw detection and tensile testing, screen out products with internal defects or substandard performance, ensuring that the final automotive aluminum alloy components leaving the factory are of reliable quality and meet high standards for properties such as fracture toughness.

[0052] Example 1

[0053] Aluminum alloy composition: According to mass percentage, weigh 1.2% of silicon (Si), 0.8% of magnesium (Mg), 0.3% of copper (Cu), 0.2% of manganese (Mn), 0.05% of titanium (Ti), and the balance is aluminum (Al) and inevitable impurities.

[0054] Preparation method

[0055] Melting: Add the above raw materials to a melting furnace and heat to 720°C for melting. After the raw materials are completely melted, stir for 15 minutes. Add 0.1% hexachloroethane refining agent to the melt and refine at 720°C for 20 minutes. After refining, let it stand for 10 minutes and remove the surface scum.

[0056] Casting: The temperature of the refined aluminum alloy melt is controlled at 680°C, and the melt is poured into a water-cooled crystallizer using a semi-continuous casting process. The casting speed is controlled at 60 mm / min and the cooling water flow rate is 8 L / min to obtain an aluminum alloy ingot.

[0057] Homogenization treatment: heat the aluminum alloy ingot to 480℃, keep it at this temperature for 8 hours, and then cool it to room temperature with the furnace.

[0058] Extrusion molding: The homogenized ingot is heated to 420° C., placed in an extruder, and extruded according to the profile structure of claim 1. The extrusion speed is controlled at 3 mm / s and the extrusion ratio is 20 to obtain a preliminarily formed aluminum alloy profile.

[0059] Solution treatment: Heat the extruded aluminum alloy profile to 500℃, keep it warm for 1 hour, and then quickly place it in a water tank with a water temperature of 20℃ for water quenching at a cooling rate of 50℃ / s.

[0060] Aging treatment: Place the aluminum alloy profile after solution treatment in an aging furnace, first age it at 120°C for 6 hours, then raise the temperature to 160°C and continue ageing for 4 hours.

[0061] Processing and Inspection: The aging-treated aluminum alloy profiles are machined to meet the dimensional requirements for automotive aluminum alloy components. Ultrasonic flaw detection and tensile testing are performed on the components, and the test results show that the fracture toughness of the components meets the expected requirements.

[0062] Example 2

[0063] Aluminum alloy composition: According to mass percentage, weigh 1.8% of silicon (Si), 1.5% of magnesium (Mg), 0.8% of copper (Cu), 0.5% of manganese (Mn), 0.15% of titanium (Ti), and the balance is aluminum (Al) and inevitable impurities.

[0064] Preparation method

[0065] Melting: Add the raw materials to the melting furnace and heat to 760℃ for melting. After the raw materials are completely melted, stir for 25 minutes. Add 0.3% of the melt weight of carbon tetrachloride refining agent to the melt and refine at 740℃ for 30 minutes. After refining, let it stand for 15 minutes and remove the surface scum.

[0066] Casting: The temperature of the refined aluminum alloy melt is controlled at 720°C. The melt is poured into a water-cooled crystallizer using a semi-continuous casting process. The casting speed is controlled at 80 mm / min and the cooling water flow rate is 12 L / min to obtain an aluminum alloy ingot.

[0067] Homogenization treatment: heat the aluminum alloy ingot to 520℃, keep it at this temperature for 12 hours, and then cool it to room temperature in the furnace.

[0068] Extrusion molding: The homogenized ingot is heated to 460° C., placed in an extruder, and extruded according to the profile structure of claim 1. The extrusion speed is controlled at 5 mm / s and the extrusion ratio is 30 to obtain a preliminarily formed aluminum alloy profile.

[0069] Solution treatment: Heat the extruded aluminum alloy profile to 540℃, keep it warm for 2 hours, and then quickly place it in a water tank with a water temperature of 30℃ for water quenching at a cooling rate of 60℃ / s.

[0070] Aging treatment: Place the aluminum alloy profile after solution treatment in an aging furnace, first age it at 140°C for 8 hours, then raise the temperature to 180°C and continue ageing for 6 hours.

[0071] Processing and Inspection: The aging-treated aluminum alloy profiles are machined to meet the dimensional requirements for automotive aluminum alloy components. Ultrasonic flaw detection and tensile testing are performed on the components, and the test results indicate that the components have excellent fracture toughness, meeting the requirements of the automotive industry.

[0072] Example 3

[0073] Aluminum alloy composition: According to mass percentage, weigh 1.5% silicon (Si), 1.2% magnesium (Mg), 0.6% copper (Cu), 0.3% manganese (Mn), 0.1% titanium (Ti), and the balance is aluminum (Al) and inevitable impurities.

[0074] Preparation method

[0075] Melting: Add the raw materials to the melting furnace and heat to 740°C for melting. After the raw materials are completely melted, stir for 20 minutes. Add a refining agent of a mixture of hexachloroethane and carbon tetrachloride (mass ratio 1:1) accounting for 0.2% of the melt mass to the melt. Refine at 730°C for 25 minutes. After refining, let it stand for 12 minutes and remove the surface scum.

[0076] Casting: The temperature of the refined aluminum alloy melt is controlled at 700°C, and the melt is poured into a water-cooled crystallizer using a semi-continuous casting process. The casting speed is controlled at 70 mm / min and the cooling water flow rate is 10 L / min to obtain an aluminum alloy ingot.

[0077] Homogenization treatment: heat the aluminum alloy ingot to 500℃, keep it at this temperature for 10 hours, and then cool it to room temperature in the furnace.

[0078] Extrusion molding: The homogenized ingot is heated to 440° C., placed in an extruder, and extruded according to the profile structure of claim 1. The extrusion speed is controlled at 4 mm / s and the extrusion ratio is 25 to obtain a preliminarily formed aluminum alloy profile.

[0079] Solution treatment: Heat the extruded aluminum alloy profile to 520℃, keep it warm for 1.5 hours, and then quickly place it in a water tank with a water temperature of 25℃ for water quenching at a cooling rate of 55℃ / s.

[0080] Aging treatment: The aluminum alloy profile after solution treatment is placed in an aging furnace, first aged at 130°C for 7 hours, then heated to 170°C for another 5 hours.

[0081] Processing and Inspection: The aging-treated aluminum alloy profiles were machined to meet the dimensional requirements for automotive aluminum alloy components. Ultrasonic flaw detection and tensile testing were performed on the components, and the test results showed that the components performed well in all performance indicators, with fracture toughness meeting expectations.

[0082] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solution and inventive concept of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. An automotive aluminum alloy component with excellent fracture toughness, characterized in that: The aluminum alloy components include, by mass percentage, silicon (Si) 1.2-1.8%, magnesium (Mg) 0.8-1.5%, copper (Cu) 0.3-0.8%, manganese (Mn) 0.2-0.5%, titanium (Ti) 0.05-0.15%, and the balance being aluminum (Al) and unavoidable impurities; The cross section of the profile is a rectangular frame (1) structure, and the rectangular frame (1) extends along the long side direction; a transverse rib (2) is provided between the midpoints of the two short sides of the rectangular frame (1), and the transverse rib (2) is parallel to the long side of the rectangular frame (1) and has two ends fixedly connected to the midpoints of the short sides of the rectangular frame (1); The transverse rib (2) is provided with a plurality of ring-shaped parts (3) distributed at equal distances, and the transverse rib (2) divides each of the ring-shaped parts (3) into two equal halves; An X-shaped reinforcement rib (4) is provided in the inner ring of each of the ring-shaped members (3), and the X-shaped reinforcement rib (4) cooperates with the transverse rib (2) to divide the ring-shaped member (3) into 6 equal parts; The X-shaped reinforcement rib (4) has four extensions extending out of the ring-shaped member (3), the four extensions are respectively connected to the long sides of the rectangular frame (1), and there is a certain distance between the connection points of each two adjacent extensions and the long sides of the rectangular frame (1); Every two adjacent ring-shaped parts (3) are connected by two arc-shaped parts (5), and the two arc-shaped parts (5) are axially symmetrically distributed with the transverse rib (2) as the symmetry axis, and the curvature of the two arc-shaped parts (5) is convex in the direction close to the transverse rib (2).

2. The automotive aluminum alloy component with excellent fracture toughness according to claim 1, characterized in that: A connecting rib (6) is connected between the midpoint of each arc-shaped member (5) and the adjacent long side of the rectangular frame (1), and the connecting rib (6) is perpendicular to the long side connected to the rectangular frame (1).

3. The automotive aluminum alloy component with excellent fracture toughness according to claim 1, characterized in that: The four extensions of the X-shaped reinforcement rib (4) are connected to the long sides of the rectangular frame (1) by welding or riveting.

4. The automotive aluminum alloy component with excellent fracture toughness according to claim 1, characterized in that: The arc-shaped member (5), the ring-shaped member (3) and the rectangular frame (1) are connected by integral molding or welding.

5. A method for preparing an automotive aluminum alloy component with excellent fracture toughness, characterized in that: The following steps are involved: Melting: Pure aluminum and various alloying elements are added to a melting furnace according to the proportion of aluminum alloy components. The temperature is raised to 720-760°C for melting. After the raw materials are completely melted, they are stirred for 15-25 minutes. A refining agent accounting for 0.1-0.3% of the melt mass is added to the melt. The melt is refined at 720-740°C for 20-30 minutes. After refining, the melt is allowed to stand for 10-15 minutes and the surface scum is removed. The aluminum alloy components include, by mass percentage, 1.2-1.8% silicon (Si), 0.8-1.5% magnesium (Mg), 0.3-0.8% copper (Cu), 0.2-0.5% manganese (Mn), 0.05-0.15% titanium (Ti), and the balance is aluminum (Al) and unavoidable impurities. Casting: The refined aluminum alloy melt temperature is controlled at 680-720℃, and the melt is poured into a water-cooled crystallizer using a semi-continuous casting process. The casting speed is controlled at 60-80mm / min, and the cooling water flow rate is 8-12L / min to obtain an aluminum alloy ingot; Homogenization treatment: heat the aluminum alloy ingot to 480-520℃, keep it at this temperature for 8-12 hours, and then cool it to room temperature with the furnace; Extrusion molding: heating the homogenized ingot to 420-460° C., placing it in an extruder, and extruding it according to the profile structure of claim 1, with the extrusion speed controlled at 3-5 mm / s and the extrusion ratio at 20-30, to obtain a preliminarily formed aluminum alloy profile; Solution treatment: Heat the extruded aluminum alloy profile to 500-540℃, keep it warm for 1-2 hours, then quickly place it in a water tank with a water temperature of 20-30℃ for water quenching, with a cooling rate of not less than 50℃ / s; Aging treatment: Place the aluminum alloy profile after solution treatment into an aging furnace, first age it at 120-140℃ for 6-8 hours, then raise the temperature to 160-180℃ and continue ageing for 4-6 hours; Processing and inspection: The aluminum alloy profiles after aging treatment are mechanically processed to meet the dimensional requirements of automotive aluminum alloy components. The components are subjected to ultrasonic flaw detection, tensile testing and other tests to screen out products that meet the fracture toughness requirements.

6. The method for preparing an automotive aluminum alloy component with excellent fracture toughness according to claim 4, characterized in that: The refining agent is hexachloroethane, carbon tetrachloride or one or more mixtures of hexachloroethane and carbon tetrachloride.

7. The method for preparing an automotive aluminum alloy component with excellent fracture toughness according to claim 4, characterized in that: In the semi-continuous casting process, the inner wall of the crystallizer is coated with graphite lubricant.

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