Aluminum alloy plate as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of aluminum alloy materials, and particularly relates to an aluminum alloy plate and a preparation method and application thereof. The aluminum alloy plate comprises, by mass, 0.10%-0.15% of copper, 0.40%-0.70% of magnesium, 0.40%-0.55% of silicon, 0.05%-0.10% of iron, 0.04%-0.10% of boron, inevitable impurities and the balance aluminum, the inevitable impurities comprise vanadium, titanium, chromium and manganese, and the total mass percentage of the inevitable impurities is 0.01%-0.03%. The yield strength of the aluminum alloy plate can reach 255 MPa and above, the tensile strength reaches 280 MPa and above, and the conductivity reaches 58.0% IACS and above.

Description

Technical Field

[0001] This invention belongs to the field of aluminum alloy material technology, specifically relating to an aluminum alloy sheet, its preparation method, and its application. Background Technology

[0002] In the power distribution systems of new energy vehicles and charging piles, aluminum alloys have shown significant advantages as a substitute for copper: they can achieve a weight reduction of about 30% and a cost reduction of about 50% for the same current carrying capacity, and also possess characteristics such as lightweight and easy recyclability. Among them, low-alloyed Al-Mg-Si alloys have become important conductive aluminum alloy products due to their combination of high strength, good conductivity, and low cost. However, with the rapid expansion of the new energy vehicle market and the popularization of high-voltage fast charging technology, the industry has placed higher demands on the strength and conductivity of Al-Mg-Si alloy sheets—aluminum alloys strengthened by traditional methods cannot simultaneously meet the requirements of high strength and high conductivity, and this contradiction has become a key technical challenge restricting its further application.

[0003] Currently, the performance regulation of Al-Mg-Si alloys is mainly achieved through melt purification, alloy element design, rare earth microalloying, and heat treatment. However, each method has its shortcomings: (1) Alloy element design: when Mg / Si≈1, the combination of strength and conductivity is better; when Mg / Si>2, the performance improvement is limited; and when Mg / Si<1, the window for improving strength and conductivity is narrow. (2) Boring treatment: by reacting with elements such as Ti and V to generate borides and then separating them, the Ti and V content in aluminum can be reduced. The content can be increased to improve electrical conductivity, but the effect on strength improvement is limited; (3) Rare earth microalloying: rare earth elements such as Ce and La can react with impurities to generate compounds, purify the melt and improve performance, but will significantly increase raw material costs and process control difficulty; (4) Heat treatment: although aging treatment can improve electrical conductivity, it will sacrifice strength; dual-stage aging treatment can promote the precipitation of small-sized, high-density β" phase, which can make the tensile strength reach 225MPa and the electrical conductivity reach 56.8%IACS, but still cannot meet the needs of higher performance scenarios.

[0004] Although existing technologies attempt to balance strength and conductivity through multi-dimensional regulation, the synergistic improvement of high strength and high conductivity has not yet broken through the bottleneck. Especially in scenarios with more stringent requirements for conductive material performance, such as high-voltage fast charging, the performance of traditional Al-Mg-Si alloys is no longer able to meet actual needs. There is an urgent need to develop a new aluminum alloy sheet technology that can achieve a dual improvement in mechanical properties and conductivity through optimized composition design and preparation process. Summary of the Invention

[0005] Based on this, by adjusting the Cu content in the Al-Mg-Si alloy sheet and performing medium-temperature rolling after conventional artificial aging treatment of the aluminum alloy sheet, and controlling the cooling rate of subsequent cooling to room temperature, an aluminum alloy sheet with excellent mechanical properties and electrical conductivity can be obtained.

[0006] To achieve the above objectives, the present invention can adopt the following technical solutions:

[0007] This invention provides an aluminum alloy sheet comprising, by mass percentage: 0.10%–0.15% copper, 0.40%–0.70% magnesium, 0.40%–0.55% silicon, 0.05%–0.10% iron, 0.04%–0.10% boron, and unavoidable impurities and the balance aluminum. The unavoidable impurities include vanadium, titanium, chromium, and manganese, and the total mass percentage of the unavoidable impurities is 0.01%–0.03%.

[0008] Preferably, the mass fraction of copper in the above-mentioned aluminum alloy sheet is 0.13% to 0.15%.

[0009] Preferably, the aluminum alloy sheet is selected from any one of the following:

[0010] (a1) Including, by mass percentage: 0.11% copper, 0.54% magnesium, 0.45% silicon, 0.07% iron, 0.08% boron, with an unavoidable impurity mass percentage totaling 0.024%, and the balance being aluminum;

[0011] (b1) Comprising, by mass percentage: 0.13% copper, 0.58% magnesium, 0.44% silicon, 0.06% iron, 0.07% boron, with unavoidable impurities totaling 0.028% by mass, and the balance being aluminum;

[0012] (c1) Including, by mass percentage: 0.15% copper, 0.57% magnesium, 0.44% silicon, 0.07% iron, 0.08% boron, with an unavoidable impurity mass percentage totaling 0.025%, and the balance being aluminum.

[0013] Preferably, the above-mentioned aluminum alloy sheet has a yield strength ≥255MPa, a tensile strength ≥280MPa, and an electrical conductivity ≥58.0%IACS.

[0014] More preferably, the yield strength of the aluminum alloy sheet is 255MPa to 290MPa, the tensile strength is 280MPa to 310MPa, and the electrical conductivity is 58.0% IACS to 60.0% IACS.

[0015] Another aspect of the present invention provides a method for preparing the above-mentioned aluminum alloy sheet, the method comprising:

[0016] (1) Prepare the raw materials according to the proportions;

[0017] (2) Melt the raw materials and cast them to obtain ingots;

[0018] (3) The ingot is homogenized, hot-rolled and cold-rolled in sequence to obtain cold-rolled sheet material;

[0019] (4) The cold-rolled sheet is subjected to solution treatment, aging treatment, medium-temperature rolling and slow cooling in sequence to obtain aluminum alloy sheet; wherein the temperature of medium-temperature rolling is lower than the recrystallization temperature of the cold-rolled sheet and higher than the aging treatment temperature.

[0020] Preferably, in the above preparation method,

[0021] The temperature for medium-temperature rolling is 150℃~280℃; and / or

[0022] The reduction in medium-temperature rolling is ≥50%; and / or

[0023] The sheet material, after being rolled at medium temperature, is slowly cooled to room temperature to obtain an aluminum alloy sheet.

[0024] More preferably, in the above preparation method,

[0025] The reduction in medium-temperature rolling is 56%–65%; and / or

[0026] The slow cooling rate is 10℃ / h to 15℃ / h.

[0027] Preferably, the above preparation method satisfies one or more of the following conditions:

[0028] (a2) The solution treatment temperature is 500℃~550℃;

[0029] (b2) Under the conditions of (a2), the solution treatment time is 40s to 80s;

[0030] (c2) The aging treatment temperature is 70℃~180℃;

[0031] (d2) Under the conditions of (c2), the aging treatment time is 3h to 12h;

[0032] In another aspect, the present invention provides the application of the above-mentioned aluminum alloy sheet or the aluminum alloy sheet prepared by the above-mentioned preparation method in the conductive system of new energy vehicles and the power distribution system of charging piles.

[0033] The beneficial effects of this invention include:

[0034] This invention controls the Cu content (0.10%–0.15%) in Al-Mg-Si alloys, allowing copper atoms to enter the β" strengthening phase and occupy characteristic atomic positions during artificial aging. This promotes the nucleation and precipitation of the β" phase and enhances its precipitation strengthening effect, thereby improving the alloy's mechanical properties. Subsequently, medium-temperature rolling deformation introduces a large number of vacancies and dislocations. Dislocations can play a role in deformation strengthening and, together with vacancies, assist in the diffusion of Mg and Si solute atoms, promoting the growth and coarsening of the β" phase formed during aging. The density of the precipitated phase is reduced, increasing the electrical conductivity. Simultaneously, due to the effects of intermediate temperature conditions and crystal defects such as vacancies and dislocations, the remaining supersaturated solid solution atoms in the matrix continue to precipitate during slow cooling, forming fine β" phases. This strengthens the alloy's strength and further enhances its electrical conductivity. Based on this, the Al-Mg-Si alloy sheet provided by this invention can achieve a yield strength of 255 MPa or higher (e.g., 255 MPa to 280 MPa), a tensile strength of 280 MPa or higher, and an electrical conductivity of 58.0% IACS or higher. Detailed Implementation

[0035] The embodiments described are provided to better illustrate the present invention, but are not intended to limit the scope of the invention to the embodiments described. Therefore, non-essential improvements and adjustments made to the embodiments by those skilled in the art based on the above description are still within the scope of protection of the present invention.

[0036] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit this disclosure. Singular expressions include plural expressions unless they have a distinct meaning in the context. As used herein, it should be understood that terms such as “comprising,” “having,” “including,” are intended to indicate the presence of features, numbers, operations, components, parts, elements, materials, or combinations thereof. The terminology of the invention is disclosed in the specification and is not intended to exclude the possibility that one or more other features, numbers, operations, components, parts, elements, materials, or combinations thereof may be present or added. As used herein, “ / ” may be interpreted as “and” or “or,” depending on the context.

[0037] Currently, the performance regulation of Al-Mg-Si alloys is mainly achieved through melt purification, alloy element design, rare earth microalloying, and heat treatment. However, each method has its shortcomings: (1) Alloy element design: When Mg / Si < 1, the window for improving the strength and electrical conductivity of Al-Mg-Si alloys is narrow; when Mg / Si > 2, the improvement on mechanical properties is limited; when Mg / Si ≈ 1 is controlled, the strength and electrical conductivity are relatively superior; (2) Boration treatment: Borides are generated by adding B elements and reacting with Ti, V, and other elements, and then separated. (2) Reduce the Ti and V content in aluminum to improve electrical conductivity, but have limited effect on strength improvement; (3) Rare earth microalloying: rare earth elements such as Ce and La can react with impurities to generate compounds, purify the melt and improve performance, but will significantly increase raw material costs and process control difficulty; (4) Heat treatment: aging treatment can improve electrical conductivity, but will sacrifice strength; dual-stage aging treatment can promote the precipitation of small-sized, high-density β" phase, which can make the tensile strength reach 225MPa and the electrical conductivity reach 56.8%IACS, but still cannot meet the needs of higher performance scenarios.

[0038] To solve the above problems, the following technical solutions can be adopted:

[0039] In a first aspect, embodiments of the present invention provide an aluminum alloy sheet comprising, by mass percentage: 0.10%–0.15% copper, 0.40%–0.70% magnesium, 0.40%–0.55% silicon, 0.05%–0.10% iron, 0.04%–0.10% boron, and unavoidable impurities and the balance aluminum. The unavoidable impurities include vanadium, titanium, chromium, and manganese, and the total mass percentage of the unavoidable impurities is 0.01%–0.03%.

[0040] It should be noted that by controlling the content of various elements in the aluminum alloy, aluminum alloy sheets with excellent mechanical properties and high electrical conductivity can be prepared in this invention. In particular, the content of Cu is crucial. Adding too little Cu does not significantly improve mechanical properties, while adding too much Cu, although improving mechanical properties, significantly reduces electrical conductivity. Therefore, the mass percentage of copper in this invention is 0.1% to 0.15%, for example, 0.11%, 0.12%, 0.13%, or 0.14%.

[0041] In some specific examples, the mass fraction of copper in the aforementioned aluminum alloy sheet is 0.13% to 0.15%.

[0042] It should be noted that the mass fraction of copper in this invention is preferably 0.13% to 0.15%, such as 0.135%, 0.14%, or 0.145%.

[0043] In some specific examples, the aluminum alloy sheet is selected from any of the following:

[0044] (a1) Including, by mass percentage: 0.11% copper, 0.54% magnesium, 0.45% silicon, 0.07% iron, 0.08% boron, with an unavoidable impurity mass percentage totaling 0.024%, and the balance being aluminum;

[0045] (b1) Comprising, by mass percentage: 0.13% copper, 0.58% magnesium, 0.44% silicon, 0.06% iron, 0.07% boron, with unavoidable impurities totaling 0.028% by mass, and the balance being aluminum;

[0046] (c1) Including, by mass percentage: 0.15% copper, 0.57% magnesium, 0.44% silicon, 0.07% iron, 0.08% boron, with an unavoidable impurity mass percentage totaling 0.025%, and the balance being aluminum.

[0047] It should be noted that the aluminum alloy sheet in this invention can preferably be one of the aluminum alloy sheets listed above. The yield strength of the aluminum alloy sheet listed above can reach 255MPa or above, the tensile strength can reach 280MPa or above, and the electrical conductivity can reach 58.0% IACS or above.

[0048] In some specific examples, the yield strength of the above-mentioned aluminum alloy sheet is ≥255MPa, the tensile strength is ≥280MPa, and the electrical conductivity is ≥58.0%IACS.

[0049] It should be noted that, as described above, the aluminum alloy sheet of the present invention possesses excellent mechanical properties (e.g., yield strength and tensile strength) and electrical properties (e.g., electrical conductivity). Specifically, the yield strength of the aforementioned aluminum alloy sheet can be ≥255MPa, the tensile strength can be ≥280MPa, and the electrical conductivity can be ≥58.0%IACS.

[0050] In some specific examples, the yield strength of the above-mentioned aluminum alloy sheet is 255MPa to 290MPa, the tensile strength is 280MPa to 310MPa, and the electrical conductivity is 58.0% IACS to 60.0% IACS.

[0051] It should be noted that the yield strength of the aluminum alloy sheet in this invention can be 255MPa to 290MPa, for example 260MPa, 265MPa, 270MPa, 275MPa, 280MPa or 285MPa, etc.; the tensile strength can be 280MPa to 310MPa, for example 285MPa, 290MPa, 295MPa, 300MPa or 305MPa, etc.; and the electrical conductivity can be 58.0%IACS to 60.0%IACS, for example 58.5%IACS, 59%IACS or 59.5%IACS, etc.

[0052] Secondly, embodiments of the present invention provide a method for preparing the above-mentioned aluminum alloy sheet, the method comprising:

[0053] (1) Prepare the raw materials according to the proportions;

[0054] (2) Melt the raw materials and cast them to obtain ingots;

[0055] (3) The ingot is homogenized, hot-rolled and cold-rolled in sequence to obtain cold-rolled sheet material;

[0056] (4) The cold-rolled sheet is subjected to solution treatment, aging treatment, medium-temperature rolling and slow cooling in sequence to obtain aluminum alloy sheet; wherein the temperature of medium-temperature rolling is lower than the recrystallization temperature of the cold-rolled sheet and higher than the aging treatment temperature.

[0057] It should be noted that this invention introduces a large number of vacancies and dislocation defects through medium-temperature rolling deformation. Dislocations can play a role in deformation strengthening and, together with vacancies, assist in the diffusion of Mg and Si solute atoms, promoting the growth and coarsening of the β" phase formed during aging treatment, reducing the density of precipitated phases, and improving electrical conductivity. Simultaneously, due to the combined effect of medium-temperature conditions and crystal defects such as dislocations, the remaining supersaturated solid solution atoms continue to precipitate during slow cooling, forming fine β" phases, thereby strengthening the alloy's strength and further improving electrical conductivity. Based on this, the magnesium-silicon-based aluminum alloy sheet provided by this invention can achieve a yield strength of 255 MPa or higher, a tensile strength of 280 MPa or higher, and an electrical conductivity of 58.0% IACS or higher.

[0058] It should also be noted that the temperature of the medium-temperature rolling in this invention is lower than the recrystallization temperature and higher than the aging treatment temperature. On the one hand, this ensures the forming of the plate and avoids cracking; on the other hand, it avoids the rapid growth and coarsening of the already formed β" phase, which reduces mechanical properties, and allows the remaining supersaturated solid solution atoms in the matrix to continue to precipitate, thereby strengthening the alloy.

[0059] In some specific examples, the temperature of the medium-temperature rolling process in the above preparation method is 150℃~280℃.

[0060] It should be noted that the temperature of the medium-temperature rolling in this invention can preferably be between 150℃ and 280℃, such as 170℃, 200℃, 230℃, 250℃, or 270℃. Furthermore, the reduction amount during medium-temperature rolling is preferably ≥50%, as alloy sheets prepared with this reduction amount exhibit superior performance.

[0061] In some specific examples, the reduction during medium-temperature rolling is ≥50% in the above preparation method.

[0062] It should be noted that if the reduction during medium-temperature rolling is less than 50% in this invention, a high density of dislocations may not be obtained to achieve work hardening, thus failing to enhance mechanical properties. If the cooling rate after medium-temperature deformation is too fast, the remaining supersaturated solid solution atoms in the matrix will not have enough time to precipitate, which will have an adverse effect on both strength and electrical conductivity.

[0063] In some specific examples, the reduction during medium-temperature rolling in the above preparation method is 56% to 65%.

[0064] It should be noted that the reduction amount of the medium-temperature rolling in this invention can be further preferably 56% to 65%, such as 58%, 60% or 63%.

[0065] In some specific examples, in the above preparation method, the plate after medium-temperature rolling is slowly cooled to room temperature to obtain an aluminum alloy plate.

[0066] In some specific examples, the slow cooling rate in the above preparation method is 10℃ / h to 15℃ / h.

[0067] It should be noted that the slow cooling rate in this invention can be 10℃ / h to 15℃ / h, for example, 11℃ / h, 12℃ / h, 13℃ / h, or 14℃ / h. Furthermore, it should be understood that the cooling method is well-known to those skilled in the art, such as water cooling, mist cooling, or air cooling.

[0068] In some specific examples, the above preparation method satisfies one or more of the following conditions:

[0069] (a2) The solution treatment temperature is 500℃~550℃;

[0070] (b2) Under the conditions of (a2), the solution treatment time is 40s to 80s;

[0071] (c2) The aging treatment temperature is 70℃~180℃;

[0072] (d2) Under the conditions of (c2), the aging treatment time is 3h to 12h;

[0073] It should be noted that, in conditions (a2) and (b2) above, the solution treatment temperature can preferably be 500℃~550℃, such as 510℃, 520℃, 530℃ or 540℃, etc. At this temperature, the solution treatment time can be 40s~80s, such as 50s, 60s or 70s, etc. Under this solution treatment temperature and time, the prepared aluminum alloy sheet has better performance. In addition, in conditions (c2) and (d2) above, the aging treatment temperature can preferably be 70℃~180℃, such as 100℃, 130℃, 150℃ or 170℃, etc. At this temperature, the aging treatment time can be 3h~12h, such as 5h, 8h or 10h, etc. Under this aging treatment temperature and time, the prepared aluminum alloy sheet has better performance.

[0074] It should also be noted that the preparation method in this invention can satisfy any one of conditions (a2) to (d2), and preferably all of the above conditions are satisfied at the same time.

[0075] In some specific examples, the above preparation method also satisfies one or more of the following conditions:

[0076] (a3) Smelting includes: adding pure aluminum ingots and aluminum intermediate alloy ingots into a smelting furnace and heating and melting them according to the alloy ratio, with a melting temperature of 730℃~750℃. After refining, slag removal and degassing, they are semi-continuously cast into flat ingots with a casting temperature of 690℃~710℃.

[0077] (b3) Homogenization includes: removing defects at the head and tail of the flat ingot, as well as surface segregation and coarse grain layer by sawing and milling. Then, the flat ingot is placed in a vertical pusher heating furnace for homogenization heat treatment. The homogenization temperature is 540℃~560℃ and the holding time is 6h~12h.

[0078] (c3) Hot rolling includes: hot rolling the homogenized flat ingot at a hot rolling temperature of 500℃~530℃ and a final rolling temperature of 300℃~350℃ to obtain hot rolled coil.

[0079] (c4) Cold rolling includes: cold rolling the hot-rolled coil to obtain a cold-rolled coil that meets the thickness requirements.

[0080] It should be noted that the preparation method in this invention can satisfy any one of conditions (a3) ​​to (d4), preferably all of the above conditions are satisfied at the same time; more preferably all of conditions (a2) to (d2) and (a3) ​​to (d4) are satisfied at the same time.

[0081] Thirdly, embodiments of the present invention provide an application of the above-mentioned aluminum alloy sheet or the aluminum alloy sheet prepared by the above-mentioned preparation method in the conductive system of new energy vehicles and the power distribution system of charging piles.

[0082] It should be noted that, as mentioned above, the aluminum alloy sheet in this invention can achieve a strength of 255 MPa or higher, a tensile strength of 280 MPa or higher, and an electrical conductivity of 58.0% IACS or higher; that is, the aluminum alloy sheet in this invention has both excellent mechanical properties and electrical conductivity, and can well replace copper, and can be used in the conductive system of new energy vehicles and the power distribution system of charging piles.

[0083] To better understand the present invention, specific examples are provided below to further illustrate the content of the present invention, but the content of the present invention is not limited to the examples below.

[0084] In the following examples, the rolling reduction is the reduction rate, which is (original thickness before rolling - thickness after rolling) / original thickness before rolling.

[0085] Example 1

[0086] (1) Prepare raw materials according to the proportions; wherein, the raw material formula is as follows by mass percentage: copper 0.11%, magnesium 0.54%, silicon 0.45%, iron 0.07%, boron 0.08%, unavoidable impurities (vanadium, titanium, chromium and manganese) totaling 0.024% by mass, with the balance being aluminum;

[0087] (2) The raw materials are melted and cast to obtain ingots; wherein the melting temperature is 739℃ and the casting temperature is 701℃.

[0088] (3) The ingot is homogenized, hot-rolled, and cold-rolled in sequence to form a plate; wherein the homogenization temperature is 548℃ and the holding time is 8h; the hot rolling temperature is 515℃; the final rolling temperature is 320℃ to obtain hot-rolled coil; then the hot-rolled coil is cold-rolled to obtain a cold-rolled coil that meets the thickness requirements.

[0089] (4) The plate is subjected to solution treatment, aging treatment, medium-temperature rolling and cooling in sequence to obtain a high-conductivity and high-strength Al-Mg-Si-Cu alloy plate; wherein, the solution treatment is to hold the plate at 530℃ for 60s; the aging treatment is to hold the plate after solution treatment at 180℃ for 5h; the medium-temperature rolling is to roll the plate after aging treatment at 250℃ with a rolling reduction of 56%; after medium-temperature rolling, the plate is air-cooled to 25℃ with a cooling rate of about 11.5℃ / h.

[0090] Example 2

[0091] Example 2 is largely the same as Example 1, except that the raw material formulation is different. Otherwise, it is the same as Example 1, and a high-conductivity and high-strength Al-Mg-Si-Cu alloy plate is prepared. In Example 2, the raw material formulation by mass percentage is as follows: copper 0.13%, magnesium 0.58%, silicon 0.44%, iron 0.06%, boron 0.07%, and the total mass percentage of unavoidable impurities (vanadium, titanium, chromium and manganese) is 0.028%, with the balance being aluminum.

[0092] Example 3

[0093] Example 2 is largely the same as Example 1, except that the raw material formulation is different. Otherwise, it is the same as Example 1, and a high-conductivity and high-strength Al-Mg-Si-Cu alloy plate is prepared. In Example 2, the raw material formulation by mass percentage is as follows: copper 0.15%, magnesium 0.57%, silicon 0.44%, iron 0.07%, boron 0.08%, and the total mass percentage of unavoidable impurities (vanadium, titanium, chromium and manganese) is 0.025%, with the balance being aluminum.

[0094] Example 4

[0095] Example 4 is largely the same as Example 1, except that the aging treatment parameters in step (4) are different. Otherwise, it is the same as Example 1. A high-conductivity and high-strength Al-Mg-Si-Cu alloy plate is prepared. The aging treatment parameters in Example 4 are: heat treatment at 120℃ for 10h.

[0096] Example 5

[0097] Example 5 is largely the same as Example 1, except that the aging treatment parameters in step (4) are different. Otherwise, it is the same as Example 1. A high-conductivity and high-strength Al-Mg-Si-Cu alloy plate is prepared. The aging treatment parameters in Example 4 are: 80℃ for 12h.

[0098] Example 6

[0099] Example 6 is largely the same as Example 1, except that the medium-temperature rolling parameters in step (4) are different. Otherwise, it is the same as Example 1. A high-conductivity and high-strength Al-Mg-Si-Cu alloy plate is prepared. The medium-temperature rolling parameters in Example 6 are: rolling at 250℃ with a rolling reduction of 65%.

[0100] Example 7

[0101] Example 7 is largely the same as Example 1, except that the medium-temperature rolling and cooling parameters in step (4) are different. Otherwise, it is the same as Example 1. A high-conductivity and high-strength Al-Mg-Si-Cu alloy plate is prepared. The medium-temperature rolling parameters in Example 7 are: rolling at 200°C with a rolling reduction of 55%; the cooling parameters are: air cooling to 25°C after medium-temperature rolling with a cooling rate of about 12.5°C / h.

[0102] Example 8

[0103] Example 8 is largely the same as Example 1, except that the medium-temperature rolling and cooling parameters in step (4) are different. Otherwise, it is the same as Example 1. A high-conductivity and high-strength Al-Mg-Si-Cu alloy plate is prepared. The medium-temperature rolling parameters in Example 8 are: rolling at 170°C with a rolling reduction of 55%; the cooling parameters are: air cooling to 25°C after medium-temperature rolling with a cooling rate of about 12.1°C / h.

[0104] Comparative Example 1

[0105] Comparative Example 1 is largely the same as Example 1, except that the raw material formulation is different. Otherwise, it is the same as Example 1, and an Al-Mg-Si-Cu alloy plate is prepared. The raw material formulation in Comparative Example 1 is as follows by mass percentage: copper 0.03%, magnesium 0.56%, silicon 0.47%, iron 0.05%, boron 0.07%, and the total mass percentage of unavoidable impurities (vanadium, titanium, chromium and manganese) is 0.022%, with the balance being aluminum.

[0106] Comparative Example 2

[0107] Comparative Example 2 is largely the same as Example 1, except that the raw material formulation is different. Otherwise, it is the same as Example 1, and an Al-Mg-Si-Cu alloy plate is prepared. The raw material formulation in Comparative Example 2 is as follows by mass percentage: copper 0.08%, magnesium 0.54%, silicon 0.45%, iron 0.07%, boron 0.08%, and the total mass percentage of unavoidable impurities (vanadium, titanium, chromium and manganese) is 0.024%, with the balance being aluminum.

[0108] Comparative Example 3

[0109] Comparative Example 3 is largely the same as Example 1, except that the raw material formulation is different. Otherwise, it is the same as Example 1, and an Al-Mg-Si-Cu alloy plate is prepared. The raw material formulation of Comparative Example 3, by mass percentage, is as follows: copper 0.17%, magnesium 0.54%, silicon 0.45%, iron 0.07%, boron 0.08%, and the total mass percentage of unavoidable impurities (vanadium, titanium, chromium and manganese) is 0.024%, with the balance being aluminum.

[0110] Comparative Example 4

[0111] Comparative Example 4 is largely the same as Example 1, except for step (4). The rest is the same as Example 1, and Al-Mg-Si-Cu alloy plates are prepared. In Comparative Example 4, in step (4), medium-temperature rolling is not performed. After aging treatment, the plates are directly cooled, and the cooling rate is the same as in Example 1.

[0112] Comparative Example 5

[0113] Comparative Example 5 is largely the same as Example 1, except for step (4). The rest is the same as Example 1, and Al-Mg-Si-Cu alloy plates are prepared. In Comparative Example 5, the intermediate temperature rolling is not performed in step (4), and the aging treatment parameters are: holding at 200°C for 8 hours, and the cooling rate is the same as in Example 1.

[0114] Comparative Example 6

[0115] Comparative Example 6 is largely the same as Example 1, except for the rolling temperature in step (4). Otherwise, it is the same as Example 1, and Al-Mg-Si-Cu alloy plates are prepared. In Comparative Example 6, the rolling temperature in step (4) is 100°C, and the cooling rate is the same as in Example 1.

[0116] Performance testing

[0117] Yield strength: The yield strength of Al-Mg-Si-Cu alloy plates prepared in each embodiment and each comparative example was tested according to GB / T 228.1-2021 Part 1: Room temperature test method. The test results are shown in Table 1.

[0118] Tensile strength: The tensile strength of Al-Mg-Si-Cu alloy plates prepared in each embodiment and each comparative example was tested according to GB / T 228.1-2021 Part 1: Room temperature test method. The test results are shown in Table 1.

[0119] Electrical conductivity: The electrical conductivity of Al-Mg-Si-Cu alloy plates prepared in each embodiment and each comparative example was tested according to the test method of GB / T 12966-2022. The test results are shown in Table 1.

[0120] Table 1 Mechanical properties and electrical conductivity of Al-Mg-Si-Cu alloy plates prepared in the examples / comparative examples

[0121] Implementation / Comparative Example Yield strength / MPa Tensile strength / MPa Conductivity / % IACS Example 1 279 293 59.2 Example 2 286 305 58.5 Example 3 290 310 58.2 Example 4 272 291 58.7 Example 5 258 281 58.4 Example 6 275 290 58.4 Example 7 268 288 58.6 Example 8 276 295 58.3 Comparative Example 1 244 267 59.3 Comparative Example 2 249 272 59.0 Comparative Example 3 297 315 57.7 Comparative Example 4 239 258 57.8 Comparative Example 5 245 267 58.7 Comparative Example 6 295 320 56.2

[0122] Note: Conductivity / %IACS refers to the ratio of the conductivity of Al-Mg-Si-Cu alloy sheet to that of annealed pure copper, while 100%IACS refers to the conductivity of annealed pure copper at 20℃.

[0123] From Table 1 above, we can see that:

[0124] Among them, the Al-Mg-Si-Cu alloy plates prepared in Examples 1 to 8 have better comprehensive properties such as yield strength, tensile strength and electrical conductivity than the Al-Mg-Si-Cu alloy plates prepared in Comparative Examples 1 to 7; and the yield strength of the Al-Mg-Si-Cu alloy plates prepared in the examples can reach 255 MPa or above, the tensile strength can reach 280 MPa or above, and the electrical conductivity can reach 58.0% IACS;

[0125] Furthermore, a comparison of Example 1 with Comparative Examples 1 to 3 reveals that:

[0126] Firstly, in Comparative Example 1, the mass percentage of Cu was reduced to 0.03%, which is far lower than the Cu content (0.10%–0.15%) in this invention. The results showed that, compared to the Al-Mg-Si-Cu alloy sheet prepared in Example 1, the Al-Mg-Si-Cu alloy sheet prepared in Comparative Example 1 showed no significant change in electrical conductivity, but its yield strength and tensile strength decreased significantly.

[0127] Secondly, in Comparative Example 2, the mass percentage of Cu was reduced to 0.08%, which is lower than the Cu content (0.1% to 0.15%) in this invention. The results showed that, compared with the Al-Mg-Si-Cu alloy plate prepared in Example 1, the electrical conductivity of the Al-Mg-Si-Cu alloy plate prepared in Comparative Example 2 did not change significantly, but the yield strength and tensile strength decreased significantly.

[0128] Third, in Comparative Example 3, the mass percentage of Cu was increased to 0.17%, which is higher than the Cu content (0.1% to 0.15%) in this invention. The results showed that, compared with the Al-Mg-Si-Cu alloy plate prepared in Example 1, the Al-Mg-Si-Cu alloy plate prepared in Comparative Example 3 had higher mechanical properties, but the electrical conductivity was significantly reduced and was lower than 58.0% IACS.

[0129] Furthermore, comparing Example 1 with Comparative Examples 4 and 5 reveals that:

[0130] Firstly, in Comparative Example 4, after aging treatment, the material was directly cooled without undergoing medium-temperature rolling. Other steps and raw material ratios were the same as in Example 1. The results showed that, compared with the Al-Mg-Si-Cu alloy sheet prepared in Example 1, the mechanical properties and electrical conductivity of the Al-Mg-Si-Cu alloy sheet prepared in Comparative Example 4 were significantly reduced.

[0131] Secondly, in Comparative Example 5, the material was directly cooled after aging treatment without undergoing medium-temperature rolling, and the aging treatment temperature and time were increased. The results showed that, compared with the Al-Mg-Si-Cu alloy sheet prepared in Example 1, the electrical conductivity of the Al-Mg-Si-Cu alloy sheet prepared in Comparative Example 5 was only slightly reduced, but the yield strength and tensile strength were significantly reduced.

[0132] In addition, a comparison between Example 1 and Comparative Example 6 reveals that:

[0133] Comparative Example 6 reduced the rolling temperature (100°C) to below the aging treatment temperature (180°C) based on Example 1, while keeping other conditions the same as in Example 1. The results showed that the Al-Mg-Si-Cu alloy sheet prepared in Comparative Example 6 had higher mechanical properties than the Al-Mg-Si-Cu alloy sheet prepared in Example 1, but its electrical conductivity decreased significantly.

[0134] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. An aluminum alloy sheet, characterized in that, The components, by mass percentage, include: copper 0.10%–0.15%, magnesium 0.40%–0.70%, silicon 0.40%–0.55%, iron 0.05%–0.10%, boron 0.04%–0.10%, unavoidable impurities, and the balance aluminum. Unavoidable impurities include vanadium, titanium, chromium, and manganese, with a total mass percentage of 0.01%–0.03%.

2. The aluminum alloy sheet according to claim 1, characterized in that, The mass fraction of copper is 0.13% to 0.15%.

3. The aluminum alloy sheet according to claim 1, characterized in that, The aluminum alloy sheet is selected from any of the following: (a1) Including, by mass percentage: 0.11% copper, 0.54% magnesium, 0.45% silicon, 0.07% iron, 0.08% boron, with an unavoidable impurity mass percentage totaling 0.024%, and the balance being aluminum; (b1) Comprising, by mass percentage: 0.13% copper, 0.58% magnesium, 0.44% silicon, 0.06% iron, 0.07% boron, with unavoidable impurities totaling 0.028% by mass, and the balance being aluminum; (c1) Including, by mass percentage: 0.15% copper, 0.57% magnesium, 0.44% silicon, 0.07% iron, 0.08% boron, with an unavoidable impurity mass percentage totaling 0.025%, and the balance being aluminum.

4. The aluminum alloy sheet according to any one of claims 1 to 3, characterized in that, The aluminum alloy sheet has a yield strength ≥255MPa, a tensile strength ≥280MPa, and an electrical conductivity ≥58.0%IACS.

5. The aluminum alloy sheet according to claim 4, characterized in that, The yield strength of the aluminum alloy sheet is 255MPa~290MPa, the tensile strength is 280MPa~310MPa, and the electrical conductivity is 58.0%IACS~60.0%IACS.

6. The method for preparing aluminum alloy sheet according to any one of claims 1 to 5, characterized in that, Preparation methods include: (1) Prepare the raw materials according to the proportions; (2) Melt the raw materials and cast them to obtain ingots; (3) The ingot is homogenized, hot-rolled and cold-rolled in sequence to obtain cold-rolled sheet material; (4) The cold-rolled sheet is subjected to solution treatment, aging treatment, medium-temperature rolling and slow cooling in sequence to obtain aluminum alloy sheet; wherein the temperature of medium-temperature rolling is lower than the recrystallization temperature of the cold-rolled sheet and higher than the aging treatment temperature.

7. The preparation method according to claim 6, characterized in that, The temperature for medium-temperature rolling is 150℃~280℃; and / or The reduction in medium-temperature rolling is ≥50%; and / or The sheet material, after being rolled at medium temperature, is slowly cooled to room temperature to obtain an aluminum alloy sheet.

8. The preparation method according to claim 7, characterized in that, The reduction in medium-temperature rolling is 56%–65%; and / or The slow cooling rate is 10℃ / h to 15℃ / h.

9. The preparation method according to any one of claims 6 to 8, characterized in that, The preparation method satisfies one or more of the following conditions: (a2) The solution treatment temperature is 500℃~550℃; (b2) Under the conditions of (a2), the solution treatment time is 40s to 80s; (c2) The aging treatment temperature is 70℃~180℃; (d2) Under the conditions of (c2), the aging treatment time is 3h to 12h.

10. The application of the aluminum alloy sheet according to any one of claims 1 to 5 or the aluminum alloy sheet prepared by any one of claims 6 to 9 in the conductive system of new energy vehicles and the power distribution system of charging piles.