Al-Mg-Si alloy and preparation method and application thereof

Abstract

The invention discloses an Al-Mg-Si alloy as well as a preparation method and application of the Al-Mg-Si alloy. The Al-Mg-Si series alloy is prepared from the following components in percentage by mass: 0.8 percent to 1.1 percent of Mg, 0.7 percent to 0.9 percent of Si, less than 0.15 percent of Fe, 0.6 percent to 0.8 percent of Cu, 0.10 percent to 0.30 percent of Mn, 0.10 percent to 0.15 percent of Cr, less than 0.05 percent of Zn, 0.004 percent to 0.008 percent of Ti and the balance of Al and inevitable impurities. According to the invention, Mg, Si, Fe, Cu, Mn, Cr, Zn, Ti and Al are limited in the range of the invention, and through reasonable matching and synergistic effect, the Al-Mg-Si alloy has high strength, good corrosion resistance and high fatigue resistance.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of alloy materials, in particular to an Al-Mg-Si alloy and a preparation method and application thereof. BACKGROUND

[0002] In recent years, with the development and maturity of the agricultural unmanned aerial vehicle market, lightweight and reliability have become the key to the competition in the agricultural unmanned aerial vehicle market. By reducing the empty weight, the energy consumption of the unmanned aerial vehicle can be reduced, the operation efficiency can be improved, the damage to crops can be reduced, and the unmanned aerial vehicle is more easy to control and less likely to be damaged. At the same time, as the application scenarios of the agricultural unmanned aerial vehicle are continuously expanded, the load capacity is continuously improved, the influence of corrosive medium and alternating load needs to be considered, the service conditions are more and more severe, and higher requirements are put forward for the safety of the main load-bearing parts of the unmanned aerial vehicle.

[0003] Therefore, it is of great significance to develop an alloy material with high strength, high corrosion resistance and high fatigue strength for application in the main structural parts of the agricultural unmanned aerial vehicle, so as to improve the lightweight, service life and environmental adaptability of the agricultural unmanned aerial vehicle. SUMMARY

[0004] The present application aims at at least solving one of the problems existing in the prior art. To this end, the present application provides, in a first aspect, an Al-Mg-Si alloy having high strength, corrosion resistance and high fatigue performance.

[0005] The present application provides, in a second aspect, a preparation method of the Al-Mg-Si alloy.

[0006] The present application provides, in a third aspect, an application of the Al-Mg-Si alloy.

[0007] According to an embodiment of the first aspect of the present application, an Al-Mg-Si alloy is provided, comprising the following components calculated by mass percentage:

[0008] Mg: 0.8% to 1.1%, Si: 0.70% to 0.9%, Fe <0.15%, Cu: 0.6% to 0.8%, Mn: 0.10% to 0.30%, Cr: 0.10% to 0.15%, Zn <0.05%, Ti: 0.004% to 0.008%, and the rest is Al and unavoidable impurities.

[0009] According to a preferred embodiment of the present application, the mass ratio of Mg and Si is 0.89 to 1.57. Thus, when the mass ratio of Mg and Si is within the above range, the strength can be improved without reducing the corrosion resistance.

[0010] The Al-Mg-Si alloy according to the embodiment of the present application has at least the following beneficial effects:

[0011] The present application limits Mg, Si, Fe, Cu, Mn, Cr, Zn, Ti and Al within the range of the present application, and through reasonable collocation and synergistic effect, the Al-Mg-Si alloy of the present application has high strength, good corrosion resistance and high fatigue resistance.

[0012] Further, the present application controls the content of Mg at 0.8% to 1.1% and the content of Si at 0.7% to 0.91%, which can ensure high strength and corrosion resistance.

[0013] Further, the Al-Mg-Si alloy in the present application adds proper Cu element, which can ensure high alloy strength without reducing corrosion resistance.

[0014] Further, Mn can convert AlFeSi phase into stable sub-micron size α-AlMnFeSi phase, which has non-coherent relationship with the matrix and is difficult to dissolve, can effectively pin the grain boundary, inhibit recrystallization, reduce the proportion of large-angle grain boundaries, increase the resistance of fatigue crack propagation along the grain boundary, and improve the fatigue performance of the alloy.

[0015] The addition of Cr can also refine the grain, consume Mn and Fe in the alloy, form Al7(CrFe) and Al 12 (CrMn) compounds, pin the grain boundary and inhibit dynamic recrystallization.

[0016] Therefore, the combined addition of Mn and Cr and the limitation of Mn content at 0.1% to 0.30% and Cr content at 0.10% to 0.15% can more effectively inhibit recrystallization and improve the tensile strength and intergranular corrosion resistance of the alloy.

[0017] According to the second aspect of the present application, a method for preparing the Al-Mg-Si alloy according to the first aspect of the present application is provided, which comprises the following steps:

[0018] Mg, Si, Fe, Cu, Mn, Cr, Zn, Ti and Al are mixed, smelted, cast, homogenized, extruded, quenched in line and artificially aged to obtain the Al-Mg-Si alloy.

[0019] According to a preferred embodiment of the present application, the smelting temperature is 700°C to 780°C.

[0020] According to a preferred embodiment of the present application, the temperature of the melting is 700℃, 710℃, 720℃, 730℃, 740℃, 750℃, 760℃, 770℃, 780℃ or a sub-range consisting of any two of them.

[0021] According to a preferred embodiment of the present application, the casting is semi-continuous casting.

[0022] According to a preferred embodiment of the present application, the temperature of the casting is 690℃-710℃.

[0023] According to a preferred embodiment of the present application, the temperature of the casting is 690℃, 695℃, 700℃, 705℃, 710℃ or a sub-range consisting of any two of them.

[0024] According to a preferred embodiment of the present application, the speed of the casting is 55-70mm / min.

[0025] According to a preferred embodiment of the present application, the speed of the casting is 55mm / min, 60mm / min, 65mm / min, 70mm / min or a sub-range consisting of any two of them.

[0026] According to a preferred embodiment of the present application, the homogenization treatment is performed in two stages, the first stage at 530℃-540℃ and the second stage at 565℃-575℃.

[0027] According to a preferred embodiment of the present application, the first stage homogenization treatment is performed for ≥2h. For example, 2h, 3h, 4h, 5h, 6h, 8h, 9h, 10h.

[0028] According to a preferred embodiment of the present application, the second stage homogenization treatment is performed for ≥18h. For example, 18h, 19h, 20h, 21h, 22h, 23h, 24h, 25h.

[0029] According to a preferred embodiment of the present application, the cooling method during the homogenization treatment includes air cooling and water mist.

[0030] According to a preferred embodiment of the present application, the extrusion forming conditions include at least:

[0031] (1) the temperature of the aluminum rod is 550℃-570℃;

[0032] (2) the temperature of the mold is 480℃-490℃;

[0033] (3) the outlet temperature is 540℃-570℃;

[0034] (4) the extrusion ratio is 70-100;

[0035] (5) the extrusion speed is 7-9 m / min.

[0036] Therefore, when the extrusion ratio is limited within the range of the application, the as-cast structure can be effectively eliminated, the grain is refined, and the fatigue strength of the profile is improved.

[0037] According to a preferred embodiment of the application, the extrusion ratio is 70, 75, 80, 85, 90, 95, 100 or a sub-range consisting of any two of the values.

[0038] According to a preferred embodiment of the application, the online quenching is by water immersion cooling.

[0039] According to a preferred embodiment of the application, the artificial aging temperature is 170-200℃. Therefore, the strength is good.

[0040] According to a preferred embodiment of the application, the artificial aging temperature is 170℃, 180℃, 185℃, 190℃, 195℃, 200℃ or a sub-range consisting of any two of the values.

[0041] According to a preferred embodiment of the application, the artificial aging time is 8-12 h.

[0042] According to a preferred embodiment of the application, the artificial aging time is 8 h, 9 h, 10 h, 11 h, 12 h or a sub-range consisting of any two of the values.

[0043] The preparation method of the Al-Mg-Si alloy according to the embodiments of the application has at least the following beneficial effects:

[0044] The application can improve the strength, corrosion resistance and high fatigue resistance after the six steps of sequentially passing each component through melting, casting, homogenization treatment, extrusion molding, online quenching and artificial aging.

[0045] The third aspect of the application provides an application of the Al-Mg-Si alloy according to the first aspect of the application in the preparation of unmanned aerial vehicle products.

[0046] Other features and advantages of the application will be described in the following description, and some will become apparent from the description, or will be understood through implementation of the application. DETAILED DESCRIPTION

[0047] The following are specific embodiments of the application, and the technical solutions of the application are further described in combination with the embodiments, but the application is not limited to these embodiments.

[0048] The reagents, methods and apparatus employed in the present application are those conventional in the art unless otherwise specified.

[0049] The raw materials used in the examples and comparative examples are shown in the following table, all of which are commercially available:

[0050]

[0051]

[0052] Example 1

[0053] This example provides an Al-Mg-Si alloy, the content of each component of which is shown in Table 1, and the preparation steps are as follows:

[0054] S1, after the components are thoroughly mixed, melting is carried out at 740±40℃, after complete melting, thorough stirring and refining, the mixture is left to stand for 80 min, and then on-line degassing and deslagging treatment is carried out. Casting is carried out by semi-continuous casting at a casting speed of 62.5±7.5 mm / min at a temperature of 700±10℃ to obtain an aluminum alloy round bar with a diameter of 178 mm;

[0055] S2, the aluminum alloy round bar is subjected to two-stage homogenization treatment (the first stage homogenization treatment temperature is 535℃, and the holding time is 2h; the second stage homogenization treatment temperature is 570℃, and the holding time is 18h), and the cooling method is strong wind + water mist.

[0056] S3, the aluminum bar is preheated at 560±10℃ before extrusion, and the die is preheated at 485±5℃. The extrusion speed used in the extrusion process is 8±1 m / min, and the extrusion ratio is 70. The outlet temperature of the extruded material is 555±15℃; and then on-line quenching is carried out by water immersion cooling.

[0057] S4, the extruded material is then subjected to artificial aging treatment, the aging temperature is 185℃, and the aging time is 10h.

[0058] Examples 2-5

[0059] Examples 2-5 provide a series of Al-Mg-Si alloys, the content of each component of which is shown in Table 1, and the preparation method is the same as that of Example 1.

[0060] Table 1 Examples 1-5

[0061] Example 1 Example 2 Example 3 Example 4 Example 5 Mg 0.8％ 0.85％ 1.1％ 0.85％ 0.85％ Si 0.9％ 0.72％ 0.70％ 0.72％ 0.72％ Fe 0.08％ 0.07％ 0.08％ 0.07％ 0.07％ Cu 0.63％ 0.63％ 0.63％ 0.72％ 0.63％ Mn 0.11％ 0.11％ 0.12％ 0.11％ 0.28％ Cr 0.11％ 0.12％ 0.12％ 0.12％ 0.15％ Zn 0.01％ 0.01％ 0.01％ 0.01％ 0.01％ Ti 0.005％ 0.004％ 0.007％ 0.008％ 0.006％ Al balance balance balance balance balance Mg / Si mass ratio 0.89 1.18 1.57 1.18 1.18

[0062] Comparative Examples 1-4

[0063] Comparative Examples 1-4 provide a series of Al-Mg-Si alloys, the content of each component is shown in Table 2, and the preparation method is the same as Example 1.

[0064] Table 2 Comparative Examples 1-4

[0065] Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Mg 0.85％ 0.85％ 0.85％ 0.85％ Si 0.60％ 0.72％ 0.72％ 0.72％ Fe 0.06％ 0.07％ 0.08％ 0.10％ Cu 0.63％ 0.63％ 0.63％ 0.01％ Mn 0.11％ 0.11％ 0.04％ 0.11％ Cr 0.12％ 0.02％ 0.12％ 0.12％ Zn 0.003％ 0.01％ 0.01％ 0.008％ Ti 0.006％ 0.005％ 0.006％ 0.007％ Al balance balance balance balance Mg / Si mass ratio 1.42 1.18 1.18 1.18

[0066] Performance test

[0067] The Al-Mg-Si alloys prepared in Examples 1-5 and Comparative Examples 1-4 of the present application were subjected to the following tests, respectively; and recorded in Table 3.

[0068] Tensile properties: The mechanical properties of the alloys were tested according to GB / T 228.1-2010 Metallic materials-Tensile testing-Part 1: Method of test at room temperature. The tensile specimens were sampled along the extrusion direction, with a size of 200x20mm, and were machined into A50 specimens. The tensile test was performed on a LEGEND 2382 universal testing machine, with an original gauge length of 50mm and a tensile speed of 5mm / min.

[0069] Intergranular corrosion: The intergranular corrosion sensitivity of the alloys was tested according to GB / T 7998-2023 Evaluation method for intergranular corrosion sensitivity of aluminum alloys. The test sample was sampled along the extrusion direction, with a size of 40x25mm. The etchant was prepared by mixing hydrofluoric acid (p=1.15g / mL), hydrochloric acid (p=1.19g / mL), nitric acid (p=1.40g / mL) and water in a volume ratio of (2+3+5+190), and stirring well. After pretreatment, the sample was immersed in a 100ml beaker, ensuring that the sample did not contact the container, and the upper end was at least 25mm from the interface of the test solution. The test temperature was 30±1℃, and the test time was 6h. After the test, the sample was taken out, and the corrosion depth at the most severely corroded position was recorded.

[0070] Exfoliation corrosion: The exfoliation corrosion sensitivity of the alloys was tested by full immersion according to GB / T 22639-2022 Exfoliation corrosion test method for aluminum alloy products. The test sample was sampled along the extrusion direction, with a size of 100x50mm. The etchant was prepared by dissolving 234g of sodium chloride and 50g of potassium nitrate in water, adding 6.7mL of nitric acid, stirring well, and then diluting with water to 1000mL. This solution contains 4.0mol of sodium chloride, 0.5mol of potassium nitrate and 0.1mol of nitric acid, and the pH value of the solution is about 0.4. After pretreatment, the sample was placed in a beaker with the test surface facing upwards and horizontally, and the test surface was at least 25mm from the interface of the test solution. The test temperature was 25±3℃, and the test time was 48h. At 48h, the sample was inspected for corrosion, and the rating results were recorded.

[0071] Stress corrosion: according to the stress corrosion sensitivity test method of GB / T 22640-2022, the stress corrosion sensitivity of the alloy is tested by slow strain rate tensile method, and the test sample is sampled along the extrusion direction. Corrosion medium (3.5%): dissolve 3.5g±0.1g (accurate to 0.1g) sodium chloride in 96.5mL water (the mass fraction of this sodium chloride solution is 3.5%), adjust the pH of this test solution to 6.4-7.2 with sodium hydroxide solution (50g / L) or hydrochloric acid solution (1+1). Slow strain rate test is used, the sample is a tensile sample with a size of 200x20mm, and is machined into an A50 sample, the sample is immersed in the corrosion medium, the tensile rate is 1x10 -6 s -1 , and the test is carried out to fracture. The stress corrosion sensitivity index is calculated according to the tensile test results.

[0072] Bench fatigue test: cycle fatigue test is carried out according to the internal bench test standard, until the sample reaches 700,000 cycles or cracks, and the cracking cycle number of the sample is recorded.

[0073] Table 3

[0074]

[0075] From the data in Table 3, within the alloy composition range of the present application, the performance of the alloy changes with the content of Mg, Si, Cu and Mn, Cr elements; but always remains in the following range:

[0076] Tensile strength≥375MPa, elongation≥9%, intergranular corrosion≤5, exfoliation corrosion is above PC level, stress corrosion sensitivity index (plasticity loss) F(δ)≤0.4, fatigue test cycle number≥3 million times.

[0077] In Comparative Example 1, the Si content is low, and the strength is reduced; in Comparative Examples 2 and 3, Cr and Mn are added respectively, and due to the weakening of grain refinement effect, the fatigue resistance is significantly reduced; in Comparative Example 4, Cu is cancelled, and the intergranular corrosion resistance is greatly improved, but the strength is reduced. It can be seen that when the composition exceeds, it cannot meet the performance requirements at the same time.

[0078] In summary, according to the alloy composition of the present application and the matched preparation process, an aluminum alloy extruded profile with high strength and excellent corrosion resistance and fatigue resistance can be obtained, which can be used for key structural parts of agricultural unmanned aerial vehicles.

[0079] The above is a detailed description combined with the embodiments of the present application, but the present application is not limited to the above embodiments, and various changes can be made within the scope of knowledge possessed by those skilled in the art without departing from the purpose of the present application.

Claims

1. An Al-Mg-Si alloy, characterized in that, Includes the following components calculated as a percentage by mass: Mg: 0.8%–1.1%, Si: 0.70%–0.9%, Fe < 0.15%, Cu: 0.6%–0.8%, Mn: 0.10%–0.30%, Cr: 0.10%–0.15%, Zn < 0.05%, Ti: 0.004%–0.008%, with the remainder being Al and unavoidable impurities.

2. The Al-Mg-Si alloy according to claim 1, characterized in that, The mass ratio of Mg to Si is 0.89 to 1.

57.

3. A method for preparing the Al-Mg-Si alloy as described in claim 1 or 2, characterized in that, Includes the following steps: The product is obtained by mixing, melting, casting, homogenizing, extruding, quenching online, and artificially aging Mg, Si, Fe, Cu, Mn, Cr, Zn, Ti, and Al.

4. The preparation method according to claim 3, characterized in that, The melting temperature is 700℃~780℃.

5. The preparation method according to claim 3, characterized in that, The casting temperature is 690℃~710℃.

6. The preparation method according to claim 3, characterized in that, The homogenization process is as follows: first, a first-stage homogenization process is performed at a temperature of 530℃~540℃; then, a second-stage homogenization process is performed at a temperature of 565℃~575℃.

7. The preparation method according to claim 3, characterized in that, The conditions for extrusion molding include at least the following: (1) The temperature of the aluminum rod is 550℃~570℃; (2) The mold temperature is 480℃~490℃; (3) The outlet temperature is 540℃~570℃; (4) The extrusion ratio is 70-100; (5) The extrusion speed is 7-9 m / min.

8. The preparation method according to claim 3, characterized in that, The temperature for artificial aging is 170–200°C.

9. The preparation method according to claim 3, characterized in that, The artificial aging time is 8h to 12h.

10. The application of the Al-Mg-Si alloy according to claim 1 or 2 in the manufacture of unmanned aerial vehicle (UAV) products.

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