An aluminum alloy and aluminum alloy structural components

Abstract

This application provides an aluminum alloy comprising, by mass percentage: 8%–11% Si, 0.01%–0.4% Cr, 0.001%–0.01% P, 0.001%–0.05% Sr, <0.12% Fe, <0.005% Mn, and 87.515%–91.988% Al. By strictly controlling the contents of Mn and Fe, and including specific amounts of Si, Cr, P, and Sr, this application achieves an aluminum alloy with ultra-high elongation while maintaining good die-casting properties. This aluminum alloy exhibits ultra-high elongation without heat treatment, making it suitable for various structural components requiring high elongation.

Description

Technical Field

[0001] This invention relates to the field of alloys, and more specifically to an aluminum alloy and an aluminum alloy structural component. Background Technology

[0002] Aluminum alloys have excellent comprehensive properties. Their low density, high strength, good electrical and thermal conductivity, and simple processing make them well-suited to meet the requirements of product structure and heat dissipation. Therefore, they are widely used in the automotive, electronics, and communications industries.

[0003] With the rise of the new energy vehicle industry, the automotive industry is facing increasing pressure to reduce costs. The urgent need for cost reduction through lightweighting has made one-piece die casting a reality. The die casting process can turn multiple parts into one, resulting in a shorter production cycle and making it more suitable for mass production.

[0004] Currently, the most widely used aluminum alloy for die casting automotive structural components is Silafont-36 aluminum alloy, known in the industry as AlSi10MnMg aluminum alloy (US grade A365). Die castings made from this alloy material require T6 or T7 heat treatment to improve elongation before they can meet performance requirements. However, high-temperature heat treatment can cause changes in the dimensions of die castings, especially for large die castings. Therefore, high-temperature heat treatment should be avoided for large die castings. Currently, the mature AlSi10MnMg aluminum alloys on the market can no longer meet performance requirements. Summary of the Invention

[0005] This application aims to at least partially solve one of the technical problems in the related art. Therefore, the purpose of this application is to provide an aluminum alloy and an aluminum alloy structural component.

[0006] In one aspect of this application, an aluminum alloy is provided, comprising, by mass percentage, the following components: Si content of 8% to 11%, Cr content of 0.01% to 0.4%, P content of 0.001% to 0.01%, Sr content of 0.001% to 0.05%, Fe content of <0.12%, Mn content of <0.005%, and Al content of 87.515% to 91.988%.

[0007] In another aspect of this application, an aluminum alloy structural component is provided, at least a portion of which is formed of the aforementioned aluminum alloy.

[0008] To prevent aluminum alloys from sticking to the mold during die casting, traditional die-casting typically adds a certain amount of Fe or Mn elements. However, Fe and Mn can form needle-like phases or large-sized precipitates, severely impairing the elongation of the aluminum alloy. This application, to achieve ultra-high elongation, employs a technical solution that strictly controls the content of Mn and Fe elements, enabling the aluminum alloy to achieve high elongation in the die-cast state. This allows large die-cast parts to meet usage requirements without heat treatment. However, during the die-casting process, the content of Mn and Fe elements is strictly controlled. When the high-temperature molten aluminum alloy comes into contact with the mold steel under high pressure, it easily reacts to form a monoclinic β-Fe phase (Al5FeSi). The β-Fe phase has a needle-like morphology, and as it grows, it easily adheres to the molten aluminum, causing sticking to the mold. To further address the adhesion problem caused by strict control of Mn and Fe content, this application's aluminum alloy contains a certain amount of Cr, which forms a tetragonal α-Fe phase (Al-Cr-Fe-Si) and inhibits the formation of the β-Fe phase, thus improving adhesion. The α-Fe phase, being a polyhedral structure, is less prone to adhesion. Furthermore, the aluminum alloy contains certain amounts of Sr and P, which further enhance elongation. Therefore, by strictly controlling the Mn and Fe content and including specific amounts of Si, Cr, P, and Sr, this application achieves an aluminum alloy with ultra-high elongation while maintaining good die-casting properties. This aluminum alloy exhibits ultra-high elongation without heat treatment and is suitable for various structural components requiring high elongation. Detailed Implementation

[0009] The embodiments of this application are described in detail below. The embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all conventional products that can be obtained commercially.

[0010] In one aspect of this application, an aluminum alloy is provided, comprising, by mass percentage, the following components: Si content of 8% to 11%, Cr content of 0.01% to 0.4%, P content of 0.001% to 0.01%, Sr content of 0.001% to 0.05%, Fe content of <0.12%, Mn content of <0.005%, and Al content of 87.515% to 91.988%.

[0011] To prevent aluminum alloys from sticking to the mold during die casting, traditional die-casting typically adds a certain amount of Fe or Mn elements. However, Fe and Mn can form needle-like phases or large-sized precipitates, severely impairing the elongation of the aluminum alloy. This application, to achieve ultra-high elongation, employs a technical solution that strictly controls the content of Mn and Fe elements, enabling the aluminum alloy to achieve high elongation in the die-cast state. This allows large die-cast parts to meet usage requirements without heat treatment. However, during the die-casting process, the content of Mn and Fe elements is strictly controlled. When the high-temperature molten aluminum alloy comes into contact with the mold steel under high pressure, it easily reacts to form a monoclinic β-Fe phase (Al5FeSi). The β-Fe phase has a needle-like morphology, and as it grows, it easily adheres to the molten aluminum, causing sticking to the mold. To further address the adhesion problem caused by strict control of Mn and Fe element content, the aluminum alloy of this application contains a certain amount of Cr element, which can form a tetragonal α-Fe phase (Al-Cr-Fe-Si), suppressing the formation of the β-Fe phase and thus improving adhesion. The α-Fe phase has a polyhedral structure, making it less prone to adhesion. The inventors of this application found that Cr element significantly improves adhesion compared to Mn element; adding 0.3% Cr element has a similar effect on improving adhesion as adding 0.6% Mn. However, adding too much Cr element can also form large-size precipitate phases, thereby impairing elongation. Extensive research by the inventors of this application has shown that controlling the Cr content in the aluminum alloy within the range of 0.05% to 0.4% can improve the adhesion problem without affecting the elongation performance of the aluminum alloy. According to some embodiments of this application, the Cr content in the aluminum alloy is 0.1% to 0.3%.

[0012] In the aluminum alloy of this application, the content of phosphorus (P) is 0.001% to 0.01%, and the content of sr is 0.001% to 0.05%. Sr can modify eutectic silicon, changing its structure from needle-like or lath-like to flocculent, thereby improving the elongation of the aluminum alloy. P can suppress the formation of bulk primary silicon, reducing the content of primary silicon in the aluminum alloy matrix to further improve the elongation. The aluminum alloy of this application contains both Sr and P, which can further improve the elongation. In the aluminum alloy of this application, the content of P can be 0.001%, 0.003%, 0.005%, 0.008%, 0.01%, etc., and the content of Sr can be 0.001%, 0.005%, 0.01%, 0.03%, 0.05%, etc. According to some embodiments of this application, the content of Sr in the aluminum alloy is 0.01% to 0.04%.

[0013] According to some embodiments of this application, the Sr content in the aluminum alloy is greater than the P content, and the ratio of Sr content to P content is ≥6. Since P in the aluminum alloy may form compounds with Sr, which is detrimental to the modification of eutectic silicon by Sr, the inventors of this application have discovered through extensive research that a ratio of Sr content to P content greater than 6 can achieve better elongation.

[0014] In the aluminum alloy of this application, the Si content is 8% to 11%, such as 8%, 9%, 10%, or 11%. According to some embodiments of this application, the Si content is 9% to 10.5%.

[0015] According to some embodiments of this application, the aluminum alloy further contains Ti, with a Ti content of 0.05% to 0.2%. The presence of 0.05% to 0.2% Ti in the aluminum alloy can refine the grain structure and further improve the strength of the aluminum alloy.

[0016] According to some embodiments of this application, the aluminum alloy further contains Mo and / or Zr, wherein the Mo content is 0.001% to 0.3% and the Zr content is 0.001% to 0.3%. Specifically, the Mo content can be 0.05%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, etc., and the Zr content can be 0.05%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, etc. The presence of Mo and / or Zr in the aluminum alloy can further improve the strength without significantly affecting the elongation. According to some embodiments of this application, when the Mo content in the aluminum alloy is 0.05% to 0.15% and the Zr content is 0.05% to 0.15%, the overall performance of the aluminum alloy is better.

[0017] According to some embodiments of this application, the content of Cu in the aluminum alloy is <0.05% and the content of Zn is <0.05%. Because Cu, Zn, and Al have a large potential difference, electrochemical corrosion is easily formed locally. Although Cu and Zn can improve the strength of the aluminum alloy, they will impair its corrosion resistance. This application strictly controls the content of Cu and Zn elements in the aluminum alloy, enabling the aluminum alloy to have excellent corrosion resistance.

[0018] According to some embodiments of this application, the Mg content in the aluminum alloy is <0.1%. Although Mg can significantly improve the strength of the aluminum alloy, it severely damages the elongation. In order to obtain an aluminum alloy with high elongation, the aluminum alloy of this application should avoid containing Mg.

[0019] According to some embodiments of this application, the aluminum alloy meets the following conditions: yield strength ≥ 120 MPa, tensile strength ≥ 260 MPa, and elongation ≥ 14%. The aluminum alloy has a certain strength and extremely high elongation, while maintaining good die-castability.

[0020] According to some embodiments of this application, the aluminum alloy has a yield strength of 140-180 MPa, a tensile strength of 260-320 MPa, and an elongation of 15-18%.

[0021] In another aspect, this application provides an aluminum alloy structural component, at least a portion of which is formed from the aforementioned aluminum alloy. This aluminum alloy structural component can be applied to various large automotive structural components and other applications requiring high elongation, such as shock absorber towers, battery trays, and rear floor frames for automobiles.

[0022] The embodiments and comparative examples of the present invention are described in detail below.

[0023] According to the aluminum alloy compositions shown in Table 1 (examples and comparative examples), various elemental and alloy raw materials were prepared. The required mass of each intermediate alloy or elemental metal was calculated based on the mass content of the aluminum alloy composition in each example and comparative example. Then, the various intermediate alloys or elemental metals were added to a melting furnace for melting and stirring to obtain a uniform aluminum alloy liquid. The content of each element was tested and adjusted until it reached the required range. A slag remover was added to remove slag, and a refining agent was used for refining and degassing. After completion, the slag was removed, the mixture was allowed to stand, and then cooled and cast into ingots. After the ingots cooled, they were die-cast, and after demolding, die-cast aluminum alloy was obtained.

[0024] Table 1

[0025]

[0026]

[0027] Performance testing:

[0028] Mechanical properties: Standard tensile test bars with a diameter of 6.4 mm were prepared by vacuum high-pressure die casting at a vacuum level of 20 mbar, a casting temperature of 690℃, and an injection speed of 1.9 m / s. Tensile testing was performed using a uniaxial quasi-static tensile test with an extensometer span of 50 mm and a test displacement rate of 2 mm / min. Yield strength, tensile strength, and elongation were then measured.

[0029] Anti-sticking property: Observe whether the aluminum alloy sticks to the mold and is difficult to remove during demolding after die casting: If the aluminum alloy does not stick to the mold and is difficult to remove during demolding, the aluminum alloy has excellent anti-sticking property; if the aluminum alloy occasionally sticks to the mold and is difficult to remove during demolding, the aluminum alloy has good anti-sticking property; if the aluminum alloy frequently sticks to the mold and is difficult to remove during demolding, the aluminum alloy has poor anti-sticking property.

[0030] Flowability: The flowability of aluminum alloys is evaluated using spiral (mosquito coil) samples. The length of the spiral sample flow is measured, and the ratio F of the length of the spiral sample flow to that of the common material ADC12 is used as an evaluation of the material's flowability. When F > 90%, the material's flowability is excellent; when 80% ≤ F ≤ 90%, the flowability is good; when 60% ≤ F < 80%, the flowability is medium; and when F < 60%, the flowability is poor.

[0031] Corrosion resistance: Neutral salt spray test, neutral salt spray concentration is 5±1%, temperature is room temperature 35±2℃, resistance to neutral salt spray for more than 480 hours is excellent, resistance to neutral salt spray for less than 480 hours is good.

[0032] The test results are shown in Table 2:

[0033] Table 2

[0034]

[0035]

[0036] As can be seen from the test results in Table 2, the aluminum alloy provided by the present invention can achieve high elongation in the die-cast state without heat treatment, thus meeting the application requirements. Furthermore, the aluminum alloy has good strength and anti-sticking properties.

[0037] In the description of this specification, references to terms such as "some embodiments" indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0038] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. An aluminum alloy, characterized in that, It includes the following components by mass percentage: The Si content is 8%~11%. The Cr content is 0.01%~0.4%. The content of phosphorus (P) is 0.001%~0.01%. The Sr content is 0.001%~0.05%. The Fe content is <0.12%. The Mn content is <0.005%. The Ti content is 0.05%~0.2%. The Al content is 87.515%~91.988%; wherein, the ratio of Sr content to P content in the aluminum alloy is ≥6, and the sum of all elements in the aluminum alloy is 100%.

2. The aluminum alloy according to claim 1, characterized in that, The aluminum alloy contains 9% to 10.5% Si.

3. The aluminum alloy according to claim 1, characterized in that, The Cr content in the aluminum alloy is 0.1% to 0.3%.

4. The aluminum alloy according to claim 1, characterized in that, The Sr content in the aluminum alloy is 0.01%~0.04%.

5. The aluminum alloy according to claim 1, characterized in that, The aluminum alloy also contains Mo, with a Mo content of 0.001% to 0.3%.

6. The aluminum alloy according to claim 1, characterized in that, The aluminum alloy also contains Zr, with a Zr content of 0.001% to 0.3%.

7. The aluminum alloy according to claim 1, characterized in that, The aluminum alloy contains <0.05% Cu, <0.05% Zn, and <0.1% Mg.

8. The aluminum alloy according to claim 1, characterized in that, The aluminum alloy meets the following conditions: yield strength ≥ 120 MPa, tensile strength ≥ 260 MPa, elongation ≥ 14%.

9. An aluminum alloy structural component, characterized in that, At least a portion of the aluminum alloy structural component is formed of the aluminum alloy as described in any one of claims 1 to 8.

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