A high-strength and high-toughness 6xxx series aluminum-magnesium-silicon alloy and its preparation method

Abstract

The application discloses a high-strength and high-toughness 6xxx series aluminum-magnesium-silicon alloy and a preparation method thereof, and belongs to the technical field of high-strength and high-toughness aluminum alloy preparation. The alloy composition is optimally designed by adding La, Sc and Zr elements, and the optimal performance of the strength and toughness of the 6xxx series aluminum-magnesium-silicon alloy is realized by combining the preparation method. The preparation method comprises the following steps: sequentially performing smelting, casting, homogenization treatment, high-temperature solid solution and rapid cooling cycle treatment, pre-aging treatment and artificial aging treatment on the aluminum-magnesium-silicon alloy. The application is high-strength and high-toughness rare earth 6xxx series aluminum-magnesium-silicon alloy with ideal Mg-Si atomic clusters and precipitated phases, which is obtained by adding specific La, Sc and Zr elements and combining specific high-temperature solid solution and rapid cooling cycle, pre-aging treatment and artificial aging treatment processes.

Description

Technical Field

[0001] The present invention belongs to the technical field of high-strength and high-toughness aluminum alloy preparation, and specifically relates to a high-strength and high-toughness 6xxx series aluminum-magnesium-silicon alloy and a preparation method thereof. Background Art

[0002] 6xxx series aluminum alloys offer a high strength-to-weight ratio, excellent formability, good corrosion resistance, no stress corrosion cracking, good weldability, and moderate strength. They are widely used as structural materials in transportation and marine environments. However, the development of modern industry has placed higher demands on the strength and toughness of 6xxx series aluminum alloys.

[0003] Invention patent CN101100717A introduces a method for producing a high-strength aluminum-magnesium-silicon alloy with excellent forgeability. By adding iron additives, manganese additives, chromium additives, and titanium-boron refiners to the alloy, and then melting, furnace-deforming, purifying, casting into rods, homogenizing the rods, and forced water cooling, the aluminum-magnesium-silicon alloy has high strength and tensile strength, is not easy to deform or break, and can meet the requirements of automotive control arms.

[0004] Patent CN109593996A introduces a squeeze-cast high-strength and toughness aluminum-magnesium-silicon-chromium alloy material prepared using squeeze casting technology and a T6 heat treatment process. By adding chromium and iron elements to the alloy and undergoing solid solution and aging processes, the alloy has high strength and toughness, a low tendency to stick to the mold, and good forming performance, making it suitable for manufacturing parts or components with lightweight requirements.

[0005] Patent CN1085754256A introduces a non-heat-treatment strengthened high-strength and high-toughness die-cast aluminum-magnesium-silicon alloy and its preparation method. By adding Mn, Ti, Be, Ca, V, Zr, and RE elements and undergoing smelting, refining, metamorphism, pouring, die-casting and other processes, the aluminum-magnesium-silicon alloy obtained by non-heat treatment has the characteristics of high strength and high toughness under cast conditions, and can achieve good die-casting performance, meeting the application needs of large thin-walled body structural parts in the automotive industry.

[0006] The aluminum alloy material obtained by the above process forms different microstructures through various heat treatments such as solutionizing and aging, as well as non-heat treatments, improving the alloy's strength, tensile strength, and formability. However, the improvement in strength and toughness is still unsatisfactory. Therefore, it is necessary to provide a processing technology to improve the strength and toughness of 6xxx series aluminum-magnesium-silicon alloys, further expanding the application of 6xxx series aluminum-magnesium-silicon alloys in transportation and marine environments. Summary of the Invention

[0007] In view of the above-mentioned defects of the prior art, the present application provides a high-strength and high-toughness 6xxx series aluminum-magnesium-silicon alloy and a preparation method thereof. The present application adds La, Sc and Zr elements, and combines high-temperature solid solution and rapid cooling cycles, pre-aging treatment and artificial aging treatment processes to obtain the required Mg-Si atomic clusters and precipitated phases to improve the strength and toughness of the 6xxx series aluminum-magnesium-silicon alloy.

[0008] To achieve the above-mentioned object, the technical solution adopted by the present application is as follows:

[0009] The present application provides a high-strength and high-toughness 6xxx series aluminum-magnesium-silicon alloy and a preparation method thereof. The present application adds La, Sc and Zr elements, and combines high-temperature solid solution and rapid cooling cycles, pre-aging treatment and artificial aging treatment processes to obtain the required Mg-Si atomic clusters and precipitated phases to improve the strength and toughness of the 6xxx series aluminum-magnesium-silicon alloy.

[0010] (1) Melting, casting and homogenization treatment of the aluminum-magnesium-silicon alloy;

[0011] (2) High-temperature solid solution and rapid cooling cycle treatment of the homogenized aluminum-magnesium-silicon alloy; the cycle number is not less than 10 times, and the interval time of each cycle is not less than 5 minutes;

[0012] (3) Pre-aging treatment and then artificial aging treatment of the high-temperature solid solution and rapid cooling cycle treated aluminum-magnesium-silicon alloy to obtain the high-strength and high-toughness 6xxx series aluminum-magnesium-silicon alloy;

[0013] In the step (1), the aluminum-magnesium-silicon alloy comprises the following components with the mass percentage: 0.6-1.5% Mg, 0.5-1.7% Si, 0.05-0.2% La, 0.1-0.7% Sc, 0.1-0.8% Zr, and the balance of Al and inevitable impurities.

[0014] As a preferred embodiment of the present application, the solid solution treatment specifically comprises: rapidly heating the aluminum-magnesium-silicon alloy to 565-580℃ at a speed of 150℃ / s, performing high-temperature solid solution treatment, controlling the temperature range within 10℃, and the solid solution time being 10-30 minutes.

[0015] As a preferred embodiment of the present application, the rapid cooling specifically comprises: spraying the aluminum-magnesium-silicon alloy with a water flow of 0.1Mpa-0.3MPa to cool it at a speed of 300℃ / s.

[0016] As a preferred embodiment of the present application, in the high-temperature solid solution and rapid cooling cycle treatment, the first high-temperature solid solution temperature is 580℃, the solid solution time is 20-30 minutes, the rapid cooling is to 20℃, and the cycle is more than 10 times, and the solid solution time of each cycle is gradually decreased to ensure that the aluminum alloy has an ideal cavity density.

[0017] As a preferred embodiment of the present invention, the pre-aging treatment temperature is 80-100° C. and the holding time is 30 min, so that the alloy obtains solute atomic clusters with a Mg / Si ratio of 1, which can provide excellent heterogeneous nucleation sites for subsequent artificial aging precipitation phases, facilitating nucleation.

[0018] As a preferred embodiment of the present invention, the artificial aging treatment temperature is 200-230°C and the aging time is 30-50 minutes to ensure that the aluminum alloy obtains the required precipitation phase sequence and the precipitation phase that enhances the strength and toughness of the alloy, thereby obtaining a high-strength and high-toughness aluminum alloy.

[0019] As a preferred embodiment of the present invention, in step (1), the mass ratio of Mg to Si in the aluminum-magnesium-silicon alloy is 1.

[0020] The present invention also claims protection for the high-strength and high-toughness 6xxx series aluminum-magnesium-silicon alloy prepared by the preparation method of the high-strength and high-toughness 6xxx series aluminum-magnesium-silicon alloy.

[0021] The principle of the preparation method of high-strength and high-toughness 6xxx series aluminum-magnesium-silicon alloy is:

[0022] The present invention uses a cycle of rapid heating to the solution temperature + rapid cooling and water quenching to retain a very high vacancy concentration in the aluminum-magnesium-silicon alloy matrix, repeatedly transporting solute atoms through the vacancies, greatly promoting the formation of Mg-Si clusters. At the same time, the addition of La, Sc and Zr elements significantly improves the degree of crystal refinement. Pre-aging treatment is then used to provide favorable heterogeneous nucleation sites for the precipitate phase required for subsequent artificial aging precipitation, thereby suppressing the effects of natural aging on the aluminum-magnesium-silicon alloy. Through the synergistic effect of the above-mentioned processes, the present invention enables the aluminum-magnesium-silicon alloy material to have high strength and toughness.

[0023] Compared with the prior art, the present invention has the following advantages: Compared with conventional aluminum-magnesium-silicon alloy production processes, the present invention, on the one hand, refines the alloy's grain size and suppresses the formation of coarse grains by adding rare earth elements; on the other hand, through a specific high-temperature solution treatment, solution treatment time, rapid heating + rapid cooling cycle, pre-aging, and artificial aging treatment process, it ensures the formation of Mg-Si atomic clusters and promotes the formation of the desired precipitation phase. The present invention achieves a high-strength and high-toughness rare earth 6xxx aluminum-magnesium-silicon alloy with ideal Mg-Si atomic clusters and precipitation phases by adding specific La, Sc, and Zr elements, combined with a specific high-temperature solution treatment and rapid cooling cycle, pre-aging treatment, and artificial aging treatment process. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a flow chart for the preparation process of high-strength and high-toughness 6xxx series aluminum-magnesium-silicon alloys. DETAILED DESCRIPTION

[0025] In order to better illustrate the purpose, technical solutions and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments.

[0026] Example 1

[0027] A method for preparing a high-strength and high-toughness 6xxx series aluminum-magnesium-silicon alloy comprises the following steps:

[0028] (1) The aluminum-magnesium-silicon alloy with the chemical composition shown in Table 1 was smelted, cast, and homogenized. The alloy was heated to 800°C to 850°C and melted. After the alloy was completely melted, it was stirred, refined, and impurity-removed to obtain a molten alloy. The molten alloy was then held at 750°C for 30 minutes and then poured into a preheated mold to form an aluminum alloy ingot with a thickness of 100 mm. The aluminum alloy ingot was homogenized at 460°C for 12 hours to obtain a homogenous ingot.

[0029] (2) After completion, the as-cast aluminum alloy was rapidly heated from 150°C to 565°C for 30 minutes of high-temperature solution treatment to uniformly distribute all elements. It was then cooled at a rate of 300°C / s using a 0.1 MPa water jet. This high-temperature solution treatment + rapid cooling cycle was repeated 10 times with a 5-minute interval between each cycle. The alloy was then immediately subjected to a 30-minute holding time, a pre-aging treatment at 80°C, and then an artificial aging treatment with aging parameters of 30 minutes × 200°C. The tensile strength and elongation of the resulting aluminum alloy are shown in Table 2.

[0030] Table 1

[0031]

[0032] Table 2

[0033] Yield strength / MPa Tensile strength / MPa Elongation 355 382 21％

[0034] Example 2

[0035] A method for preparing a high-strength and high-toughness 6xxx series aluminum-magnesium-silicon alloy comprises the following steps:

[0036] (1) The aluminum-magnesium-silicon alloy with the chemical composition shown in Table 3 was smelted, cast, and homogenized. The alloy was heated to 800°C to 850°C and melted. After the alloy was completely melted, it was stirred, refined, and impurity-removed to obtain a molten alloy. The molten alloy was then held at 750°C for 30 minutes and then poured into a preheated mold to form an aluminum alloy ingot with a thickness of 100 mm. The aluminum alloy ingot was homogenized at 460°C for 12 hours to obtain a homogenous ingot.

[0037] (2) After completion, the as-cast aluminum alloy was rapidly heated from 150°C to 570°C for 25 minutes of high-temperature solution treatment to uniformly distribute all elements. It was then cooled at a rate of 320°C / s using a 0.15 MPa water jet. This high-temperature solution treatment + rapid cooling cycle was repeated 12 times with a 7-minute interval between each cycle. The alloy was then immediately subjected to a 30-minute holding time, a pre-aging treatment at 90°C, and then an artificial aging treatment with aging parameters of 35 minutes × 210°C. The tensile strength and elongation of the resulting aluminum alloy are shown in Table 4.

[0038] Table 3

[0039]

[0040] Table 4

[0041] Yield strength / MPa Tensile strength / MPa Elongation 359 386 23％

[0042] Example 3

[0043] A method for preparing a high-strength and high-toughness 6xxx series aluminum-magnesium-silicon alloy comprises the following steps:

[0044] (1) The aluminum-magnesium-silicon alloy with the chemical composition shown in Table 5 was smelted, cast, and homogenized. The alloy was heated to 800°C to 850°C and melted. After the alloy was completely melted, it was stirred, refined, and impurity-removed to obtain a molten alloy. The molten alloy was then held at 750°C for 30 minutes and then poured into a preheated mold to form an aluminum alloy ingot with a thickness of 100 mm. The aluminum alloy ingot was homogenized at 460°C for 12 hours to obtain a homogenous ingot.

[0045] (2) After completion, the as-cast aluminum alloy was rapidly heated from 150°C to 570°C for 10 minutes of high-temperature solution treatment to uniformly distribute all elements. It was then cooled at a rate of 350°C / s using a 0.3 MPa water jet. This high-temperature solution treatment + rapid cooling cycle was repeated 15 times with a 10-minute interval. The alloy was then immediately subjected to a 30-minute holding time, a pre-aging treatment at 90°C, and then an artificial aging treatment with aging parameters of 45 minutes × 220°C. The tensile strength and elongation of the resulting aluminum alloy are shown in Table 6.

[0046] Table 5

[0047]

[0048]

[0049] Table 6

[0050] Yield strength / MPa Tensile strength / MPa Elongation 380 400 23.5％

[0051] Example 4

[0052] A method for preparing a high-strength and high-toughness 6xxx series aluminum-magnesium-silicon alloy comprises the following steps:

[0053] (1) The aluminum-magnesium-silicon alloy having the chemical composition shown in Table 7 was smelted, cast, and homogenized. The alloy was heated to 800°C to 850°C and melted. After the alloy was completely melted, it was stirred, refined, and impurity-removed to obtain a molten alloy. The molten alloy was then held at 750°C for 30 minutes and then poured into a preheated mold to form an aluminum alloy ingot with a thickness of 100 mm. The aluminum alloy ingot was homogenized at 460°C for 12 hours to obtain a homogenous ingot.

[0054] (2) After completion, the as-cast aluminum alloy was rapidly heated from 150°C to 580°C for 30 minutes of high-temperature solution treatment to uniformly distribute all elements. It was then cooled at a rate of 340°C / s using a 0.25 MPa water jet. This high-temperature solution treatment + rapid cooling cycle was repeated 12 times with a 10-minute interval between each cycle. Immediately thereafter, the alloy was subjected to a 30-minute holding time, a pre-aging treatment at 100°C, and then an artificial aging treatment with aging parameters of 45 minutes × 230°C. The tensile strength and elongation of the resulting aluminum alloy are shown in Table 8.

[0055] Table 7

[0056]

[0057] Table 8

[0058] Yield strength / MPa Tensile strength / MPa Elongation 358 386 24％

[0059] Example 5

[0060] A method for preparing a high-strength and high-toughness 6xxx series aluminum-magnesium-silicon alloy comprises the following steps:

[0061] (1) The aluminum-magnesium-silicon alloy with the chemical composition shown in Table 1 was smelted, cast, and homogenized. The alloy was heated to 800°C to 850°C and melted. After the alloy was completely melted, it was stirred, refined, and impurity-removed to obtain a molten alloy. The molten alloy was then held at 750°C for 30 minutes and then poured into a preheated mold to form an aluminum alloy ingot with a thickness of 100 mm. The aluminum alloy ingot was homogenized at 460°C for 12 hours to obtain a homogenous ingot.

[0062] (2) After completion, the as-cast aluminum alloy was rapidly heated from 150°C to 565°C for 30 minutes of high-temperature solution treatment to uniformly distribute all elements. It was then cooled at a rate of 300°C / s using a 0.1 MPa water jet. The high-temperature solution treatment + rapid cooling cycle was repeated 10 times with a 5-minute interval between each cycle. The high-temperature heat treatment time was reduced by 2 minutes for each cycle. Immediately thereafter, the alloy was subjected to a 30-minute holding time, a pre-aging treatment at 80°C, and then an artificial aging treatment with an aging parameter of 30 minutes × 200°C. The tensile strength and elongation of the final aluminum alloy are shown in Table 9.

[0063] Table 9

[0064] Yield strength / MPa Tensile strength / MPa Elongation 425 410 25％

[0065] Since the solution time of each cycle decreases gradually in the high-temperature solution + rapid cooling cycle of Example 5, it is beneficial to ensure that the aluminum alloy has an ideal vacancy density, and then repeatedly transport solute atoms through vacancies, which greatly promotes the formation of Mg-Si clusters and can play a role in refining grains, so that the aluminum-magnesium-silicon alloy material has high strength and toughness.

[0066] Comparative Example 1

[0067] A method for preparing a high-strength and high-toughness 6xxx series aluminum-magnesium-silicon alloy comprises the following steps:

[0068] (1) The aluminum-magnesium-silicon alloy with the chemical composition shown in Table 1 was smelted, cast, and homogenized. The alloy was heated to 800°C to 850°C and melted. After the alloy was completely melted, it was stirred, refined, and impurity-removed to obtain a molten alloy. The molten alloy was then held at 750°C for 30 minutes and then poured into a preheated mold to form an aluminum alloy ingot with a thickness of 100 mm. The aluminum alloy ingot was homogenized at 460°C for 12 hours to obtain a homogenous ingot.

[0069] (2) After completion, the as-cast aluminum alloy was rapidly heated from 150°C to 570°C for 5 hours of high-temperature solution treatment to uniformly distribute all elements. It was then cooled at a rate of 200°C / s using a 0.05 MPa water jet. The alloy was immediately subjected to a 30-min holding time and pre-aging treatment at 85°C, followed by artificial aging treatment with aging parameters of 30 minutes × 200°C. The tensile strength and elongation of the resulting aluminum alloy are shown in Table 10.

[0070] Table 10

[0071] Yield strength / MPa Tensile strength / MPa Elongation 330 352 18％

[0072] By comparison with Example 1, it can be seen that the shorter the solution time and the faster high-temperature solution + rapid cooling cycle treatment can significantly improve the strength and toughness of the material. This is because compared with the longer solution time in Comparative Example 1 and the lack of rapid heating high-temperature solution + rapid cooling cycle treatment, the solution time in Example 1 is relatively short and the subsequent number of clusters formed is relatively large. The rapid heating high-temperature solution + rapid cooling cycle increases the vacancy concentration, thereby increasing the subsequent formation of clusters, obtaining the desired precipitation phase, and thus increasing the strength and toughness of the aluminum alloy.

[0073] Comparative Example 2

[0074] A method for preparing a high-strength and high-toughness 6xxx series aluminum-magnesium-silicon alloy comprises the following steps:

[0075] (1) The aluminum-magnesium-silicon alloy with the chemical composition shown in Table 3 was smelted, cast, and homogenized. The alloy was heated to 800°C to 850°C and melted. After the alloy was completely melted, it was stirred, refined, and impurity-removed to obtain a molten alloy. The molten alloy was then held at 750°C for 30 minutes and then poured into a preheated mold to form an aluminum alloy ingot with a thickness of 100 mm. The aluminum alloy ingot was homogenized at 460°C for 12 hours to obtain a homogenous ingot.

[0076] (2) After completion, the as-cast aluminum alloy was rapidly heated from 150°C to 570°C for 25 minutes of high-temperature solution treatment to uniformly distribute all elements. The alloy was then cooled at a rate of 320°C / s using a 0.15 MPa water jet. This high-temperature solution treatment followed by rapid cooling was repeated 12 times, with a 7-minute interval between each cycle. The alloy was then artificially aged at 210°C for 5 hours. The tensile strength and elongation of the resulting aluminum alloy are shown in Table 11.

[0077] Table 11

[0078] Yield strength / MPa Tensile strength / MPa Elongation 342 365 21％

[0079] By comparison with Example 2, it can be seen that pre-aging and relatively shortened artificial aging time can significantly improve the strength and toughness of the material. This is because, compared with the lack of pre-aging treatment and long artificial aging time in Comparative Example 2, the pre-aging treatment in Example 2 effectively inhibits the natural aging process of the alloy, reduces the negative effects of natural aging, and significantly promotes subsequent artificial aging. The longer the artificial aging time, the less conducive it is to the precipitation of the desired β-precipitate phase. When pre-aging treatment and a shorter artificial aging time are present, the strength and toughness of the aluminum alloy are increased.

[0080] Comparative Example 3

[0081] The preparation method of the high-strength and high-toughness 6xxx series aluminum-magnesium-silicon alloy described in this comparative example differs from that in Example 3 only in the chemical composition of the aluminum-magnesium-silicon alloy. The chemical composition of the alloy in this comparative example is shown in Table 12. The tensile strength and elongation of the resulting aluminum alloy are shown in Table 13.

[0082] Table 12

[0083]

[0084] Table 13

[0085] Yield strength / MPa Tensile strength / MPa Elongation 352 365 19％

[0086] By comparison with Example 3, it can be seen that the strength and toughness of the aluminum alloy sample without the addition of La, Sc and Zr rare earth elements are lower than those with La, Sc and Zr rare earth elements. This is because the presence of La, Sc and Zr rare earth elements significantly refines the grains of the aluminum-magnesium-silicon alloy; and the residual rare earth elements are enriched at the grain boundaries, inhibiting the diffusion of other elements and slowing down the growth rate of the α-Al matrix, thereby improving the strength and toughness of the alloy.

[0087] Comparative Example 4

[0088] The method for preparing the high-strength and high-toughness 6xxx series aluminum-magnesium-silicon alloy described in this comparative example differs from that in Example 4 only in the chemical composition of the aluminum-magnesium-silicon alloy. The chemical composition of the alloy in this comparative example is shown in Table 14. The tensile strength and elongation of the resulting aluminum alloy are shown in Table 15.

[0089] Table 14

[0090]

[0091] Table 15

[0092] Yield strength / MPa Tensile strength / MPa Elongation 330 350 19％

[0093] By comparison with Example 4, it can be seen that the further the Mg / Si ratio deviates from 1, the lower the strength and toughness. This is because when the Mg / Si ratio is approximately 1, Mg-Si atomic clusters are formed, providing excellent heterogeneous nucleation sites for the β-precipitation phase during subsequent artificial aging. However, when the Mg / Si ratio deviates from 1, these clusters cannot serve as nucleation sites for the β-precipitation phase during subsequent artificial aging, resulting in a decrease in strength during the subsequent aging process. When the Mg / Si content is approximately 1, the strength and toughness of the alloy are improved.

[0094] Comparative Example 5

[0095] The preparation method of the high-strength and high-toughness 6xxx series aluminum-magnesium-silicon alloy described in this comparative example differs from that in Example 3 only in the chemical composition of the aluminum-magnesium-silicon alloy. The chemical composition of the alloy in this comparative example is shown in Table 16. The tensile strength and elongation of the resulting aluminum alloy are shown in Table 17.

[0096] Table 16

[0097]

[0098] Table 17

[0099] Yield strength / MPa Tensile strength / MPa Elongation 350 362 18％

[0100] The addition of Sc element can form stable and fine phase particles ScMg2Si2 with Mg and Si. These particles are distributed at the grain boundaries, hindering the slip of dislocations and the activity of grain boundaries, and can also play a role in refining the grains in the alloy, making the particle size in the alloy smaller, thereby effectively improving the strength and toughness of the alloy.

[0101] Comparative Example 6

[0102] The preparation method of the high-strength and high-toughness 6xxx series aluminum-magnesium-silicon alloy described in this comparative example differs from that in Example 3 only in the chemical composition of the aluminum-magnesium-silicon alloy. The chemical composition of the alloy in this comparative example is shown in Table 16. The tensile strength and elongation of the resulting aluminum alloy are shown in Table 17.

[0103] Table 16

[0104]

[0105] Table 17

[0106] Yield strength / MPa Tensile strength / MPa Elongation 346 358 17％

[0107] The increase of La element can form a stable phase LaMg2Si2 with Mg and Si. These particles will hinder the movement of dislocations and form LaSi2 compounds with Si, which plays a role in refining grains, thereby effectively improving the strength and toughness of the alloy.

[0108] Comparative Example 7

[0109] The preparation method of the high-strength and high-toughness 6xxx series aluminum-magnesium-silicon alloy described in this comparative example differs from that in Example 3 only in the chemical composition of the aluminum-magnesium-silicon alloy. The chemical composition of the alloy in this comparative example is shown in Table 18. The tensile strength and elongation of the resulting aluminum alloy are shown in Table 19.

[0110] Table 18

[0111]

[0112] Table 19

[0113] Yield strength / MPa Tensile strength / MPa Elongation 355 370 19％

[0114] The addition of Zr element can form ZrSi2 compound with Si on one hand, which can refine the grain, and the fine grain can improve the strength and toughness of the alloy, and on the other hand, ZrMg2Si2 phase is formed, which can hinder the dislocation slip, has the effect of pinning the grain boundary, hinders the migration of the grain boundary, and improves the strength and hardness of the alloy.

[0115] Finally, it should be noted that the above examples are only used to illustrate the technical solutions of the present application, and are not intended to limit the scope of protection of the present application. Although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can be modified or replaced by equivalents without departing from the essence and scope of the technical solutions of the present application.

Claims

1. A method for preparing a high-strength and high-toughness 6xxx series aluminum-magnesium-silicon alloy, characterized in that: By adding La, Sc and Zr elements, the alloy composition is optimized, combined with high temperature solution and rapid cooling cycles, pre-aging treatment and artificial aging treatment processes, to achieve the best performance in strength and toughness of 6xxx series Al-Mg-Si alloys, including the following steps: (1) Smelting, casting and homogenizing aluminum-magnesium-silicon alloy; (2) The aluminum-magnesium-silicon alloy after homogenization treatment is subjected to high-temperature solid solution and rapid cooling cycle treatment; the number of cycles is not less than 10, and the interval between each cycle treatment is not less than 5 minutes; (3) Pre-aging the recycled aluminum-magnesium-silicon alloy and then artificially aging it to obtain a high-strength and high-toughness 6xxx series aluminum-magnesium-silicon alloy; In the step (1), the aluminum-magnesium-silicon alloy comprises the following components in percentage by mass: 0.6-1.5% Mg, 0.5-1.7% Si, 0.05-0.2% La, 0.1-0.7% Sc, 0.1-0.8% Zr, and the remainder is Al and unavoidable impurities; The high-temperature solid solution specifically includes: heating the aluminum-magnesium-silicon alloy to 565-580°C at a rate of 150°C / s for a solid solution time of 10-30 minutes; The rapid cooling specifically includes: spraying the aluminum-magnesium-silicon alloy with a water flow of 0.1 MPa to 0.3 MPa to cool it at a rate of 300°C / s; The pre-aging treatment temperature is 80-100°C and the holding time is 30 minutes; The temperature of the artificial aging treatment is 200-230° C., and the aging time is 30-50 minutes.

2. The method for preparing the high-strength and high-toughness 6xxx series aluminum-magnesium-silicon alloy according to claim 1, wherein: In the high-temperature solution and rapid cooling cycle treatment, the temperature of the first high-temperature solution is 580° C., the solution time is 20-30 minutes, and the solution is rapidly cooled to 20° C. The cycle is repeated more than 10 times, and the solution time of each cycle decreases gradually.

3. The method for preparing the high-strength and high-toughness 6xxx series aluminum-magnesium-silicon alloy according to claim 1, wherein: In the step (1), the mass ratio of Mg to Si in the aluminum-magnesium-silicon alloy is 1.

0.

4. A high-strength and high-toughness 6xxx series aluminum-magnesium-silicon alloy prepared by the method for preparing a high-strength and high-toughness 6xxx series aluminum-magnesium-silicon alloy according to any one of claims 1 to 3.

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