A heat-treatment-free aluminum alloy for new energy vehicle battery pack and preparation method thereof

Abstract

The present invention provides a heat-treatment-free aluminum alloy for a new energy vehicle battery pack and a preparation method thereof. The mass percentage of the aluminum alloy is: Si: 8.75-10.25wt.%, Mg: 0.03-0.27wt.%, Mn: 0.4-0.8wt.%, Cu: 0.01-0.11wt.%, Fe: 0.08-0.27wt.%, Ti: 0.06-0.13wt.%, Sr: 0.013-0.039wt.%, V: 0.015-0.07wt.%, Ga: 0.005-0.018wt.%, Sm: 0.003-0.15wt.%; the total amount of the remaining impurities is less than or equal to 0.2wt.%, and the balance is Al. The heat-treatment-free aluminum alloy of the present application can achieve higher yield strength and elongation without heat treatment, and meets the performance requirements of an integrated die-cast heat-treatment-free aluminum alloy for a new energy vehicle battery pack.

Description

Technical Field

[0001] The present invention belongs to the field of aluminum alloy materials, and relates to an aluminum alloy material having high strength and high toughness without requiring heat treatment, and a preparation method thereof. Background Art

[0002] In recent years, driven by the dual carbon goals, the design and manufacturing of components in the new energy vehicle industry has been rapidly evolving toward lightweighting and integration. The battery pack casing, as a support and protective structure for the power battery, plays a crucial role in the battery pack system. Currently, the heavy weight of traditional battery pack casings significantly hinders the improvement of the battery pack system's energy density and the lightweighting of new energy vehicles. Therefore, there is significant room for weight reduction and efficiency improvement.

[0003] An important means of lightweighting battery pack cases is to use lightweight materials, among which aluminum alloy is an excellent lightweight material for battery packs. For a long time, high-vacuum die-casting technology has been commonly used, combined with high-strength and tough heat-treatable AlSi10MnMg materials to manufacture battery packs. However, with the rapid development of energy-saving and emission-reducing vehicles, the lightweighting, integration, and large-scale development of aluminum alloy die-cast structural parts have put forward many new performance requirements for die-cast alloys, including good casting properties, fluidity, and the requirement for no heat treatment, and excellent strength and toughness in the cast state. For example, the Silafont-36 alloy of German Rheinland Corporation has good mechanical properties but requires special high-vacuum die-casting. It must undergo T6 heat treatment to achieve the requirements for improving the comprehensive mechanical properties of the casting. Heat treatment of die-cast parts increases the process flow and cost consumption, and heat treatment easily causes deformation of the casting, resulting in a low qualified rate of finished products. C611 alloy is a non-heat-treatable die-cast alloy developed by Alcoa. This material has good toughness and is suitable for the needs of certain automotive structural parts. However, the material has a low Si content and a low yield strength, which cannot meet the strength performance requirements of battery packs. Tianjin Xinlizhong Alloy Group Co., Ltd. has disclosed a high-strength and toughness heat-treatment-free material (patent publication number: CN114293058A). By adding refractory Nb elements and high-melting-point Cr elements, Ti elements, and B elements, it improves the overall comprehensive mechanical properties of the casting. Shanghai Yongmaotai Auto Parts Co., Ltd. has disclosed a high-strength and toughness die-cast aluminum alloy and its preparation method (patent publication number: CN109881056A). Mainly through the addition of rare earth composite modification, it can obtain a high-strength and high-toughness die-cast aluminum alloy with a yield strength of 160MPa, a tensile strength of 270MPa, and an elongation of 7%. Summary of the Invention

[0004] Against this backdrop, the objective of the present invention is to provide a heat-treatment-free aluminum alloy material for new energy vehicle battery packs. This material exhibits high strength and toughness without the need for heat treatment, addresses defects such as deformation and bulging in integrated thin-walled structural parts after heat treatment, and facilitates market application. Furthermore, research and development of new high-strength and toughness die-cast aluminum alloys with a higher tolerance for Fe elements will promote the use of recycled aluminum alloys in automotive die-cast structural parts. This will not only help control component costs but also significantly reduce carbon emissions during the raw material acquisition phase, thereby significantly enhancing product competitiveness.

[0005] The technical solution is as follows:

[0006] A heat-treatment-free aluminum alloy for a new energy vehicle battery pack, comprising the following alloy components in percentage by mass: Si: 8.75-10.25 wt.%, Mg: 0.03-0.27 wt.%, Mn: 0.4-0.8 wt.%, Cu: 0.01-0.11 wt.%, Fe: 0.08-0.27 wt.%, Ti: 0.06-0.13 wt.%, Sr: 0.013-0.039 wt.%, V: 0.015-0.07 wt.%, Ga: 0.005-0.018 wt.%, Sm: 0.003-0.15 wt.%; the total amount of other impurities is less than or equal to 0.2 wt.%, and the balance is Al.

[0007] A method for preparing a heat-treatment-free aluminum alloy for a new energy vehicle battery pack, the method comprising the following steps:

[0008] 1) Material preparation and preheating: Prepare the materials according to the alloy composition ratio, preheat the raw materials to be melted to 200-220℃ and dry them.

[0009] 2) Melting: Raise the temperature to 740-760°C, melt pure aluminum and industrial silicon first, then add Al-Cu master alloy, Al-Mn master alloy, Al-V master alloy, Al-Sr master alloy, Al-Ti master alloy, and Al-Sm master alloy respectively and melt them. After melting, cool to 700-720°C, add pure Mg, and press it into the bottom of the crucible with a tool to prevent Mg from burning on the liquid surface. Finally, wrap Ga in aluminum foil and press it into the bottom of the crucible with a tool to melt and stir.

[0010] 3) Refining and degassing: Keep the temperature at 720-730℃, use rotary spray degassing equipment, and introduce nitrogen with refining agent powder into the melt for powder spray refining. The amount of refining agent added is 0.1-0.5%, and the melt is refined and degassed for 8-10 minutes.

[0011] 4) Ingot casting: The casting sample is subjected to spectral composition analysis, and after the composition is qualified, it is cast into an ingot.

[0012] 5) Die-casting: The aluminum alloy ingots are melted and then high-pressure die-casted. The die-casting process is carried out at a pressure of 350-500 bar, an injection speed of 4-6 m / s, a vacuum of 10-40 mbar, a die-casting temperature of 680-710°C, and a mold temperature of 180-220°C. The die-casting mold used is a flat die with a thickness close to the actual battery pack.

[0013] 6) Sampling test: The obtained casting flat plate mold is sampled and processed into rectangular cross-section test pieces by wire cutting, and the mechanical properties are tested using an electronic universal tensile testing machine.

[0014] The heat treatment-free aluminum alloy obtained by using the above components and preparation method has a tensile strength of 300-340 MPa, a yield strength of 145-175 MPa, and an elongation of 10-15% in the die-cast state.

[0015] Advantages and positive effects of the present invention:

[0016] Compared with the prior art, the present invention has the following advantages:

[0017] Through extensive testing and production of die-cast aluminum alloys, the inventors discovered that adding certain trace elements to the alloy can significantly optimize the mechanical properties of the alloy. The mechanism of action is as follows:

[0018] The addition of trace element Sm to the alloy has a good refining and modification effect on Al-Si alloy. The modification effect on eutectic Si makes it appear as small dots and short rods. At the same time, Sm added to the matrix can form rare earth phase Al 11 Sm3 acts as a substrate for α-Al nucleation, increasing the nucleation rate during solidification and achieving grain refinement. The addition of trace element Ga, as the Ga content increases, promotes the precipitation of Mg at grain boundaries, which in turn promotes the precipitation of the strengthening phase Mg2Si, effectively improving the mechanical properties of the alloy. The addition of trace element V can increase the tensile strength and elongation of aluminum alloys. V precipitates spherical AlFeSi(Mn+V) phases in the matrix, effectively reducing the lamellar iron-rich phases in the matrix, which helps improve the material's toughness and enable it to tolerate higher Fe contents.

[0019] The present invention creatively adds a certain proportion of V, Ga, and Sm to the aluminum alloy matrix, producing a synergistic strengthening effect on the alloy. The addition of Sm, already modified by Sr, further enhances the modification effect. The addition of V and Ga effectively improves the alloy's toughness, and the three elements work together to enhance the alloy's overall mechanical properties. Furthermore, the addition of an appropriate amount of Cu to the alloy provides solid solution strengthening, increasing the material's tensile strength.

[0020] This alloy ratio can effectively reduce the impact of high iron content on alloy performance, that is, it can tolerate a higher Fe content, thus meeting the conditions for using recycled aluminum in the future and complying with the requirements for the development of a green, low-carbon circular economy.

[0021] This aluminum alloy has excellent performance in the die-cast state and good die-casting performance. The yield strength in the die-cast state is 145-175MPa, the tensile strength is 300-340MPa, and the elongation is 10-15% (conventional commercial AlSi10MnMg alloy has a tensile strength of about 260MPa, a yield strength of about 130MPa, and an elongation of about 4% in the die-cast state).

[0022] In summary, the heat-treatment-free aluminum alloy for new energy vehicle battery packs prepared by the present invention has the characteristics of high strength and high toughness, meets the requirements of integrated die-cast heat-treatment-free aluminum alloy for new energy vehicle battery packs, and has great market application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 The microstructure morphology of the die-cast alloy of the present invention (×200).

[0024] Figure 2 The microstructure morphology (×500) of the die-cast alloy of the present invention (eutectic silicon in the structure is in the form of small dots and short rods).

[0025] Figure 3 This is a comparison chart of the room temperature tensile mechanical properties of the aluminum alloy materials prepared in Example 4 of the present invention and Comparative Example 6. DETAILED DESCRIPTION

[0026] Preferably, the heat-treatment-free aluminum alloy includes the following alloy components in mass percentage: Si: 8.75-9.5wt.%, Mg: 0.03-0.12wt.%, Mn: 0.4-0.6wt.%, Cu: 0.01-0.05wt.%, Fe: 0.08-0.12wt.%, Ti: 0.07-0.1wt.%, Sr: 0.013-0.03wt.%, V: 0.015-0.03wt.%, Ga: 0.005-0.01wt.%, Sm: 0.003-0.08wt.%; the total amount of other impurities is less than or equal to 0.2wt.%, and the balance is Al.

[0027] Preferably, the heat-treatment-free aluminum alloy includes the following alloy components in percentage by mass: Si: 9.5-9.8wt.%, Mg: 0.12-0.20wt.%, Mn: 0.4-0.6wt.%, Cu: 0.03-0.07wt.%, Fe: 0.12-0.18wt.%, Ti: 0.07-0.1wt.%, Sr: 0.02-0.035wt.%, V: 0.03-0.05wt.%, Ga: 0.008-0.012wt.%, Sm: 0.08-0.12wt.%; the total amount of other impurities is less than or equal to 0.2wt.%, and the balance is Al.

[0028] Preferably, the heat-treatment-free aluminum alloy includes the following alloy components in mass percentage: Si: 9.8-10.25wt.%, Mg: 0.20-0.27wt.%, Mn: 0.4-0.6wt.%, Cu: 0.05-0.11wt.%, Fe: 0.18-0.27wt.%, Ti: 0.07-0.1wt.%, Sr: 0.028-0.039wt.%, V: 0.05-0.07wt.%, Ga: 0.013-0.018wt.%, Sm: 0.09-0.15wt.%; the total amount of remaining impurities is less than or equal to 0.2wt.%, and the balance is Al.

[0029] Preferably, the heat-treatment-free aluminum alloy includes the following alloy components in the following mass percentages: Si: 9.15wt.%, Mg: 0.18wt.%, Mn: 0.5wt.%, Cu: 0.03wt.%, Fe: 0.11wt.%, Ti: 0.08wt.%, Sr: 0.035wt.%, V: 0.02wt.%, Ga: 0.008wt.%, Sm: 0.1wt.%; the total amount of remaining impurities is less than or equal to 0.2wt.%, and the balance is Al.

[0030] Preferably, the heat-treatment-free aluminum alloy includes the following alloy components in mass percentage: Si: 9.83wt.%, Mg: 0.16wt.%, Mn: 0.5wt.%, Cu: 0.03wt.%, Fe: 0.25wt.%, Ti: 0.08wt.%, Sr: 0.038wt.%, V: 0.04wt.%, Ga: 0.015wt.%, Sm: 0.15wt.%; the total amount of remaining impurities is less than or equal to 0.2wt.%, and the balance is Al.

[0031] The technical solution of the present application is further described in detail below in conjunction with the specification, drawings and specific embodiments, so that the advantages and features of the present invention can be more easily understood by those skilled in the art, but the scope of application of the present invention is not limited.

[0032] Example 1:

[0033] The present embodiment relates to a heat-treatment-free aluminum alloy for new energy vehicle battery packs, wherein the mass percentages of its components are as follows: Si: 8.75%; Mn: 0.6%; Mg: 0.15%; Cu: 0.03%; Ti: 0.07%; Fe: 0.08%; Sr: 0.035%; V: 0.015%; Ga: 0.01%; Sm: 0.003%; impurities are equal to 0.08%, and the balance is aluminum.

[0034] A method for preparing a heat-treatment-free aluminum alloy for a new energy vehicle battery pack according to this embodiment includes the following steps:

[0035] 1) Material preparation and preheating: Prepare the materials according to the above alloy composition ratio, preheat the prepared raw materials pure aluminum, industrial silicon, pure Mg, Al-Mn master alloy, Al-Cu master alloy, Al-Sr master alloy, Al-V master alloy, Al-Ti master alloy, and Al-Sm master alloy to 220°C and dry them;

[0036] 2) Melting: Heat to 740°C, melt pure aluminum and industrial silicon first, then add Al-Cu master alloy, Al-Mn master alloy, Al-V master alloy, Al-Sm master alloy, and Al-Ti master alloy respectively and melt them. After melting, cool to 720°C, add pure Mg, and press it into the bottom of the crucible with a tool to prevent burning on the liquid surface. After Mg is completely melted, press Ga wrapped in aluminum foil into the bottom of the crucible with a tool to melt it;

[0037] 3) Refining and degassing: add 0.5% by weight of refining agent to the aluminum liquid, use argon gas rotary degassing equipment to degas the melt for 10 minutes, then scrape off the slag on the liquid surface and let it stand for 15 minutes; the refining agent used is the slag refining covering agent produced by Zhenjiang Zhenhua Flux Factory, the same below;

[0038] 4) Ingot casting: The casting sample is subjected to spectral component analysis, and after the components are qualified, it is cast into an ingot;

[0039] 5) Die-casting process: After melting the above aluminum alloy ingot, high-pressure die-casting is performed. The die-casting process adopts a die-casting pressure of 500 bar, an injection speed of 6 m / s, a vacuum degree of 15 mbar, a die-casting temperature of 690°C, and a mold temperature of 200°C. The die-casting mold used is a flat mold close to the actual thickness of the battery pack;

[0040] 6) Sampling test: The obtained casting body is sampled and processed into test pieces with rectangular cross-sections by wire cutting, and mechanical properties tests are performed on a universal tensile testing machine.

[0041] Example 2:

[0042] The present embodiment relates to a heat-treatment-free aluminum alloy for new energy vehicle battery packs, the weight percentages of its components are as follows: Si: 9.1%; Mn: 0.6%; Mg: 0.15%; Cu: 0.03%; Ti: 0.07%; Fe: 0.25%; Sr: 0.035%; V: 0.015%; Ga: 0.01%; Sm: 0.09%; impurities are equal to 0.08%, and the balance is aluminum.

[0043] A method for preparing a heat-treatment-free aluminum alloy for a new energy vehicle battery pack according to this embodiment includes the following steps:

[0044] 1) Material preparation and preheating: Prepare the materials according to the above alloy composition ratio, preheat the prepared raw materials pure aluminum, industrial silicon, pure Mg, Al-Mn master alloy, Al-Cu master alloy, Al-Sr master alloy, Al-V master alloy, Al-Ti master alloy, and Al-Sm master alloy to 220°C and dry them;

[0045] 2) Melting: Heat to 740°C, melt pure aluminum and industrial silicon first, then add Al-Cu master alloy, Al-Mn master alloy, Al-V master alloy, Al-Sm master alloy, and Al-Ti master alloy respectively and melt them. After melting, cool to 720°C, add pure Mg, and press it into the bottom of the crucible with a tool to prevent burning on the liquid surface. After Mg is completely melted, press Ga wrapped in aluminum foil into the bottom of the crucible with a tool to melt it;

[0046] 3) Refining and degassing: Add 0.5% by weight of refining agent to the aluminum liquid, use argon rotary degassing equipment to degas the melt for 10 minutes, then scrape off the slag on the liquid surface and let it stand for 15 minutes;

[0047] 4) Ingot casting: A sample is cast for spectral analysis. Once the composition is qualified, it is cast into an ingot. 5) Die-casting: The aluminum alloy ingot is melted and then high-pressure die-casted. The die-casting process uses a die-casting pressure of 500 bar, an injection speed of 6 m / s, a vacuum of 15 mbar, a die-casting temperature of 690°C, and a mold temperature of 200°C. The die-casting mold used is a flat mold close to the actual thickness of the battery pack.

[0048] 6) Sampling test: The obtained casting body is sampled and processed into test pieces with rectangular cross-sections by wire cutting, and mechanical properties tests are performed on a universal tensile testing machine.

[0049] Example 3:

[0050] The present embodiment relates to a heat-treatment-free aluminum alloy for new energy vehicle battery packs, the weight percentages of its components are as follows: Si: 9.5%; Mn: 0.6%; Mg: 0.18%; Cu: 0.03%; Ti: 0.07%; Fe: 0.08%; Sr: 0.035%; V: 0.02%; Ga: 0.015%; Sm: 0.08%; impurities are equal to 0.08%, and the balance is aluminum.

[0051] A method for preparing a heat-treatment-free aluminum alloy for a new energy vehicle battery pack according to this embodiment includes the following steps:

[0052] 1) Material preparation and preheating: Prepare the materials according to the above alloy composition ratio, preheat the prepared raw materials pure aluminum, industrial silicon, pure Mg, Al-Mn master alloy, Al-Cu master alloy, Al-Sr master alloy, Al-V master alloy, Al-Ti master alloy, and Al-Sm master alloy to 220°C and dry them;

[0053] 2) Melting: Heat to 740°C, melt pure aluminum and industrial silicon first, then add Al-Cu master alloy, Al-Mn master alloy, Al-V master alloy, Al-Sm master alloy, and Al-Ti master alloy respectively and melt them. After melting, cool to 720°C, add pure Mg, and press it into the bottom of the crucible with a tool to prevent burning on the liquid surface. After Mg is completely melted, press Ga wrapped in aluminum foil into the bottom of the crucible with a tool to melt it;

[0054] 3) Refining and degassing: Add 0.5% by weight of refining agent to the aluminum liquid, use argon rotary degassing equipment to degas the melt for 10 minutes, then scrape off the slag on the liquid surface and let it stand for 15 minutes;

[0055] 4) Ingot casting: A sample is cast for spectral analysis. Once the composition is qualified, it is cast into an ingot. 5) Die-casting: The aluminum alloy ingot is melted and then high-pressure die-casted. The die-casting process uses a die-casting pressure of 500 bar, an injection speed of 6 m / s, a vacuum of 15 mbar, a die-casting temperature of 690°C, and a mold temperature of 200°C. The die-casting mold used is a flat mold close to the actual thickness of the battery pack.

[0056] 6) Sampling test: The obtained casting body is sampled and processed into test pieces with rectangular cross-sections by wire cutting, and mechanical properties tests are performed on a universal tensile testing machine.

[0057] Example 4:

[0058] The present embodiment relates to a heat-treatment-free aluminum alloy for new energy vehicle battery packs, the weight percentages of its components are as follows: Si: 9.8%; Mn: 0.6%; Mg: 0.18%; Cu: 0.03%; Ti: 0.07%; Fe: 0.15%; Sr: 0.035%; V: 0.02%; Ga: 0.015%; Sm: 0.1%; impurities are equal to 0.08%, and the balance is aluminum.

[0059] A method for preparing a heat-treatment-free aluminum alloy for a new energy vehicle battery pack according to this embodiment includes the following steps:

[0060] 1) Material preparation and preheating: Prepare the materials according to the above alloy composition ratio, preheat the prepared raw materials pure aluminum, industrial silicon, pure Mg, Al-Mn master alloy, Al-Cu master alloy, Al-Sr master alloy, Al-V master alloy, Al-Ti master alloy, and Al-Sm master alloy to 220°C and dry them;

[0061] 2) Melting: Heat to 740°C, melt pure aluminum and industrial silicon first, then add Al-Cu master alloy, Al-Mn master alloy, Al-V master alloy, Al-Sm master alloy, and Al-Ti master alloy respectively and melt them. After melting, cool to 720°C, add pure Mg, and press it into the bottom of the crucible with a tool to prevent burning on the liquid surface. After Mg is completely melted, press Ga wrapped in aluminum foil into the bottom of the crucible with a tool to melt it;

[0062] 3) Refining and degassing: Add 0.5% by weight of refining agent to the aluminum liquid, use argon rotary degassing equipment to degas the melt for 10 minutes, then scrape off the slag on the liquid surface and let it stand for 15 minutes;

[0063] 4) Ingot casting: A sample is cast for spectral analysis. Once the composition is qualified, it is cast into an ingot. 5) Die-casting: The aluminum alloy ingot is melted and then high-pressure die-casted. The die-casting process uses a die-casting pressure of 500 bar, an injection speed of 6 m / s, a vacuum of 15 mbar, a die-casting temperature of 690°C, and a mold temperature of 200°C. The die-casting mold used is a flat mold close to the actual thickness of the battery pack.

[0064] 6) Sampling test: The obtained casting body is sampled and processed into test pieces with rectangular cross-sections by wire cutting, and mechanical properties tests are performed on a universal tensile testing machine.

[0065] Example 5:

[0066] The present embodiment relates to a heat-treatment-free aluminum alloy for new energy vehicle battery packs, the weight percentages of its components are as follows: Si: 9.8%; Mn: 0.6%; Mg: 0.18%; Cu: 0.03%; Ti: 0.07%; Fe: 0.25%; Sr: 0.035%; V: 0.02%; Ga: 0.015%; Sm: 0.1%; impurities are equal to 0.08%, and the balance is aluminum.

[0067] A method for preparing a heat-treatment-free aluminum alloy for a new energy vehicle battery pack according to this embodiment includes the following steps:

[0068] 1) Material preparation and preheating: Prepare the materials according to the above alloy composition ratio, preheat the prepared raw materials pure aluminum, industrial silicon, pure Mg, Al-Mn master alloy, Al-Cu master alloy, Al-Sr master alloy, Al-V master alloy, Al-Ti master alloy, and Al-Sm master alloy to 220°C and dry them;

[0069] 2) Melting: Heat to 740°C, melt pure aluminum and industrial silicon first, then add Al-Cu master alloy, Al-Mn master alloy, Al-V master alloy, Al-Sm master alloy, and Al-Ti master alloy respectively and melt them. After melting, cool to 720°C, add pure Mg, and press it into the bottom of the crucible with a tool to prevent burning on the liquid surface. After Mg is completely melted, press Ga wrapped in aluminum foil into the bottom of the crucible with a tool to melt it;

[0070] 3) Refining and degassing: Add 0.5% by weight of refining agent to the aluminum liquid, use argon rotary degassing equipment to degas the melt for 10 minutes, then scrape off the slag on the liquid surface and let it stand for 15 minutes;

[0071] 4) Ingot casting: The casting sample is subjected to spectral component analysis, and after the components are qualified, it is cast into an ingot;

[0072] 5) Die-casting process: After melting the above aluminum alloy ingot, high-pressure die-casting is performed. The die-casting process adopts a die-casting pressure of 500 bar, an injection speed of 6 m / s, a vacuum degree of 15 mbar, a die-casting temperature of 690°C, and a mold temperature of 200°C. The die-casting mold used is a flat mold close to the actual thickness of the battery pack;

[0073] 6) Sampling test: The obtained casting body is sampled and processed into test pieces with rectangular cross-sections by wire cutting, and mechanical properties tests are performed on a universal tensile testing machine.

[0074] Example 6:

[0075] The present embodiment relates to a heat-treatment-free aluminum alloy for new energy vehicle battery packs, and the weight percentages of its components are as follows: Si: 10.2%; Mn: 0.6%; Mg: 0.18%; Cu: 0.03%; Ti: 0.07%; Fe: 0.12%; Sr: 0.035%; V: 0.02%; Ga: 0.005%; Sm: 0.09%; impurities are equal to 0.08%, and the balance is aluminum.

[0076] A method for preparing a heat-treatment-free aluminum alloy for a new energy vehicle battery pack according to this embodiment includes the following steps:

[0077] 1) Material preparation and preheating: Prepare the materials according to the above alloy composition ratio, preheat the prepared raw materials pure aluminum, industrial silicon, pure Mg, Al-Mn master alloy, Al-Cu master alloy, Al-Sr master alloy, Al-V master alloy, Al-Ti master alloy, and Al-Sm master alloy to 220°C and dry them;

[0078] 2) Melting: Heat to 740°C, melt pure aluminum and industrial silicon first, then add Al-Cu master alloy, Al-Mn master alloy, Al-V master alloy, Al-Sm master alloy, and Al-Ti master alloy respectively and melt them. After melting, cool to 720°C, add pure Mg, and press it into the bottom of the crucible with a tool to prevent burning on the liquid surface. After Mg is completely melted, press Ga wrapped in aluminum foil into the bottom of the crucible with a tool to melt it;

[0079] 3) Refining and degassing: Add 0.5% by weight of refining agent to the aluminum liquid, use argon rotary degassing equipment to degas the melt for 10 minutes, then scrape off the slag on the liquid surface and let it stand for 15 minutes;

[0080] 4) Ingot casting: The casting sample is subjected to spectral component analysis, and after the components are qualified, it is cast into an ingot;

[0081] 5) Die-casting process: After melting the above aluminum alloy ingot, high-pressure die-casting is performed. The die-casting process adopts a die-casting pressure of 500 bar, an injection speed of 6 m / s, a vacuum degree of 15 mbar, a die-casting temperature of 690°C, and a mold temperature of 200°C. The die-casting mold used is a flat mold close to the actual thickness of the battery pack;

[0082] 6) Sampling test: The obtained casting body is sampled and processed into test pieces with rectangular cross-sections by wire cutting, and mechanical properties tests are performed on a universal tensile testing machine.

[0083] Example 7:

[0084] The present embodiment relates to a heat-treatment-free aluminum alloy for new energy vehicle battery packs, and the weight percentages of its components are as follows: Si: 10.2%; Mn: 0.6%; Mg: 0.18%; Cu: 0.03%; Ti: 0.07%; Fe: 0.12%; Sr: 0.035%; V: 0.02%; Ga: 0.015%; Sm: 0.1%; impurities are equal to 0.08%, and the balance is aluminum.

[0085] A method for preparing a heat-treatment-free aluminum alloy for a new energy vehicle battery pack according to this embodiment includes the following steps:

[0086] 1) Material preparation and preheating: Prepare the materials according to the above alloy composition ratio, preheat the prepared raw materials pure aluminum, industrial silicon, pure Mg, Al-Mn master alloy, Al-Cu master alloy, Al-Sr master alloy, Al-V master alloy, Al-Ti master alloy, and Al-Sm master alloy to 220°C and dry them;

[0087] 2) Melting: Heat to 740°C, melt pure aluminum and industrial silicon first, then add Al-Cu master alloy, Al-Mn master alloy, Al-V master alloy, Al-Sm master alloy, and Al-Ti master alloy respectively and melt them. After melting, cool to 720°C, add pure Mg, and press it into the bottom of the crucible with a tool to prevent burning on the liquid surface. After Mg is completely melted, press Ga wrapped in aluminum foil into the bottom of the crucible with a tool to melt it;

[0088] 3) Refining and degassing: Add 0.5% by weight of refining agent to the aluminum liquid, use argon rotary degassing equipment to degas the melt for 10 minutes, then scrape off the slag on the liquid surface and let it stand for 15 minutes;

[0089] 4) Ingot casting: A sample is cast for spectral analysis. Once the composition is qualified, it is cast into an ingot. 5) Die-casting: The aluminum alloy ingot is melted and then high-pressure die-casted. The die-casting process uses a die-casting pressure of 500 bar, an injection speed of 6 m / s, a vacuum of 15 mbar, a die-casting temperature of 690°C, and a mold temperature of 200°C. The die-casting mold used is a flat mold close to the actual thickness of the battery pack.

[0090] 6) Sampling test: The obtained casting body is sampled and processed into test pieces with rectangular cross-sections by wire cutting, and mechanical properties tests are performed on a universal tensile testing machine.

[0091] Example 8:

[0092] The present embodiment relates to a heat-treatment-free aluminum alloy for new energy vehicle battery packs, the weight percentages of its components are as follows: Si: 9.8%; Mn: 0.6%; Mg: 0.18%; Cu: 0.15%; Ti: 0.07%; Fe: 0.12%; Sr: 0.035%; V: 0.02%; Ga: 0.015%; Sm: 0.12%; impurities are equal to 0.08%, and the balance is aluminum.

[0093] A method for preparing a heat-treatment-free aluminum alloy for a new energy vehicle battery pack according to this embodiment includes the following steps:

[0094] 1) Material preparation and preheating: Prepare the materials according to the above alloy composition ratio, preheat the prepared raw materials pure aluminum, industrial silicon, pure Mg, Al-Mn master alloy, Al-Cu master alloy, Al-Sr master alloy, Al-V master alloy, Al-Ti master alloy, and Al-Sm master alloy to 220°C and dry them;

[0095] 2) Melting: Heat to 740°C, melt pure aluminum and industrial silicon first, then add Al-Cu master alloy, Al-Mn master alloy, Al-V master alloy, Al-Sm master alloy, and Al-Ti master alloy respectively and melt them. After melting, cool to 720°C, add pure Mg, and press it into the bottom of the crucible with a tool to prevent burning on the liquid surface. After Mg is completely melted, press Ga wrapped in aluminum foil into the bottom of the crucible with a tool to melt it;

[0096] 3) Refining and degassing: Add 0.5% by weight of refining agent to the aluminum liquid, use argon rotary degassing equipment to degas the melt for 10 minutes, then scrape off the slag on the liquid surface and let it stand for 15 minutes;

[0097] 4) Ingot casting: The casting sample is subjected to spectral composition analysis, and after the composition is qualified, it is cast into an ingot.

[0098] 5) Die-casting process: After melting the above aluminum alloy ingot, high-pressure die-casting is performed. The die-casting process adopts a die-casting pressure of 500 bar, an injection speed of 6 m / s, a vacuum degree of 15 mbar, a die-casting temperature of 690°C, and a mold temperature of 200°C. The die-casting mold used is a flat mold close to the actual thickness of the battery pack;

[0099] 6) Sampling test: The obtained casting body is sampled and processed into test pieces with rectangular cross-sections by wire cutting, and mechanical properties tests are performed on a universal tensile testing machine.

[0100] Example 9:

[0101] The present embodiment relates to a heat-treatment-free aluminum alloy for new energy vehicle battery packs, the weight percentages of its components are as follows: Si: 9.8%; Mn: 0.6%; Mg: 0.18%; Cu: 0.25%; Ti: 0.07%; Fe: 0.12%; Sr: 0.035%; V: 0.02%; Ga: 0.015%; Sm: 0.1%; impurities are equal to 0.08%, and the balance is aluminum.

[0102] A method for preparing a heat-treatment-free aluminum alloy for a new energy vehicle battery pack according to this embodiment includes the following steps:

[0103] 1) Material preparation and preheating: Prepare the materials according to the above alloy composition ratio, preheat the prepared raw materials pure aluminum, industrial silicon, pure Mg, Al-Mn master alloy, Al-Cu master alloy, Al-Sr master alloy, Al-V master alloy, Al-Ti master alloy, and Al-Sm master alloy to 220°C and dry them;

[0104] 2) Melting: Heat to 740°C, melt pure aluminum and industrial silicon first, then add Al-Cu master alloy, Al-Mn master alloy, Al-V master alloy, Al-Sm master alloy, and Al-Ti master alloy respectively and melt them. After melting, cool to 720°C, add pure Mg, and press it into the bottom of the crucible with a tool to prevent burning on the liquid surface. After Mg is completely melted, press Ga wrapped in aluminum foil into the bottom of the crucible with a tool to melt it;

[0105] 3) Refining and degassing: Add 0.5% by weight of refining agent to the aluminum liquid, use argon rotary degassing equipment to degas the melt for 10 minutes, then scrape off the slag on the liquid surface and let it stand for 15 minutes;

[0106] 4) Ingot casting: A sample is cast for spectral analysis. Once the composition is qualified, it is cast into an ingot. 5) Die-casting: The aluminum alloy ingot is melted and then high-pressure die-casted. The die-casting process uses a die-casting pressure of 500 bar, an injection speed of 6 m / s, a vacuum of 15 mbar, a die-casting temperature of 690°C, and a mold temperature of 200°C. The die-casting mold used is a flat mold close to the actual thickness of the battery pack.

[0107] 6) Sampling test: The obtained casting body is sampled and processed into test pieces with rectangular cross-sections by wire cutting, and mechanical properties tests are performed on a universal tensile testing machine.

[0108] Example 10:

[0109] The present embodiment relates to a heat-treatment-free aluminum alloy for new energy vehicle battery packs, the weight percentages of its components are as follows: Si: 9.8%; Mn: 0.6%; Mg: 0.18%; Cu: 0.03%; Ti: 0.07%; Fe: 0.15%; Sr: 0.035%; V: 0.06%; Ga: 0.018%; Sm: 0.15%; impurities are equal to 0.08%, and the balance is aluminum.

[0110] A method for preparing a heat-treatment-free aluminum alloy for a new energy vehicle battery pack according to this embodiment includes the following steps:

[0111] 1) Material preparation and preheating: Prepare the materials according to the above alloy composition ratio, preheat the prepared raw materials pure aluminum, industrial silicon, pure Mg, Al-Mn master alloy, Al-Cu master alloy, Al-Sr master alloy, Al-V master alloy, Al-Ti master alloy, and Al-Sm master alloy to 220°C and dry them;

[0112] 2) Melting: Heat to 740°C, melt pure aluminum and industrial silicon first, then add Al-Cu master alloy, Al-Mn master alloy, Al-V master alloy, Al-Sm master alloy, and Al-Ti master alloy respectively and melt them. After melting, cool to 720°C, add pure Mg, and press it into the bottom of the crucible with a tool to prevent burning on the liquid surface. After Mg is completely melted, press Ga wrapped in aluminum foil into the bottom of the crucible with a tool to melt it;

[0113] 3) Refining and degassing: Add 0.5% by weight of refining agent to the aluminum liquid, use argon rotary degassing equipment to degas the melt for 10 minutes, then scrape off the slag on the liquid surface and let it stand for 15 minutes;

[0114] 4) Ingot casting: The casting sample is subjected to spectral component analysis, and after the components are qualified, it is cast into an ingot;

[0115] 5) Die-casting process: After melting the above aluminum alloy ingot, high-pressure die-casting is performed. The die-casting process adopts a die-casting pressure of 500 bar, an injection speed of 6 m / s, a vacuum degree of 15 mbar, a die-casting temperature of 690°C, and a mold temperature of 200°C. The die-casting mold used is a flat mold close to the actual thickness of the battery pack;

[0116] 6) Sampling test: The obtained casting body is sampled and processed into test pieces with rectangular cross-sections by wire cutting, and mechanical properties tests are performed on a universal tensile testing machine.

[0117] Comparative Example 1:

[0118] The weight percentages of the components of the aluminum alloy prepared in Comparative Example 1 are as follows: Si: 9.8%; Mn: 0.6%; Mg: 0.18%; Cu: 0.03%; Ti: 0.07%; Fe: 0.15%; Sr: 0.035%; V: 0.02%; impurities are equal to 0.08%, and the balance is aluminum.

[0119] The aluminum alloy preparation method of this comparative example is the same as that of the above embodiment.

[0120] Comparative Example 2:

[0121] The weight percentages of the components of the aluminum alloy prepared in Comparative Example 2 are as follows: Si: 9.8%; Mn: 0.6%; Mg: 0.18%; Cu: 0.03%; Ti: 0.07%; Fe: 0.15%; Sr: 0.035%; Ga: 0.015%; impurities are equal to 0.08%, and the balance is aluminum.

[0122] The aluminum alloy preparation method of this comparative example is the same as that of the above embodiment.

[0123] Comparative Example 3:

[0124] The weight percentages of the components of the aluminum alloy prepared in Comparative Example 3 are as follows: Si: 9.8%; Mn: 0.6%; Mg: 0.18%; Cu: 0.03%; Ti: 0.07%; Fe: 0.15%; Sr: 0.035%; Sm: 0.1%; impurities are equal to 0.08%, and the balance is aluminum.

[0125] The aluminum alloy preparation method of this comparative example is the same as that of the above embodiment.

[0126] Comparative Example 4:

[0127] The weight percentages of the components of the aluminum alloy prepared in Comparative Example 4 are as follows: Si: 9.8%; Mn: 0.6%; Mg: 0.18%; Cu: 0.03%; Ti: 0.07%; Fe: 0.15%; Sr: 0.035%; impurities are equal to 0.08%, and the balance is aluminum.

[0128] The aluminum alloy preparation method of this comparative example is the same as that of the above embodiment.

[0129] Comparative Example 5:

[0130] The weight percentages of the components of the aluminum alloy prepared in Comparative Example 5 are as follows: Si: 9.8%; Mn: 0.6%; Mg: 0.18%; Cu: 0.03%; Ti: 0.07%; Fe: 0.28%; Sr: 0.035%; impurities equal to 0.08%, and the balance is aluminum.

[0131] The aluminum alloy preparation method of this comparative example is the same as that of the above embodiment.

[0132] Comparative Example 6:

[0133] The weight percentages of the components of the aluminum alloy prepared in Comparative Example 6 are as follows: Si: 10.7%; Mn: 0.6%; Mg: 0.33%; Ti: 0.07%; Fe: 0.22%; Sr: 0.02%; and the balance is aluminum.

[0134] The aluminum alloy preparation method of this comparative example is the same as that of the above embodiment.

[0135] The relevant results of the above embodiments and comparative examples are shown in Table 1 and Table 2.

[0136] Table 1 (mass fraction wt%)

[0137]

[0138] Table 2 (Mechanical properties of die-cast aluminum alloy)

[0139]

[0140]

[0141] Table 1 shows the mass fractions of the aluminum alloy materials of Examples 1-10 and Comparative Examples 1-6, and Table 2 shows the mechanical properties of the die-cast aluminum alloys corresponding to Table 1. Based on the results of the Examples and Comparative Examples in Tables 1 and 2, it can be seen that when Example 4 is compared with Comparative Examples 1, 2, 3, and 4, the overall mechanical properties of the alloy are poorer when no V, Ga, or Sm elements are added to the alloy than when one of these elements is added. When the three elements are added to the alloy in a certain proportion (Example 4) compared to when no V, Ga, or Sm elements are added (Comparative Example 4), the tensile strength increases by approximately 40 MPa, the yield strength increases by approximately 27 MPa, and the elongation increases by approximately 4%, indicating that the addition of V, Ga, and Sm elements has a significant effect on improving the mechanical properties of the alloy. Furthermore, when the element addition amount is high (Example 10), there is no significant effect on improving the mechanical properties.

[0142] Comparisons of Examples 4 and 5 with Comparative Examples 4 and 5 show that when V, Ga, and Sm are added to the alloy, the elongation of the alloy changes little as the Fe content in the alloy increases, maintaining good plasticity. In contrast, the elongation of the alloy without V, Ga, and Sm decreases significantly. This demonstrates that V, Ga, and Sm can mitigate the deterioration of alloy properties caused by Fe, indicating that the aluminum alloy of the present invention can tolerate higher Fe contents without compromising the alloy's mechanical properties.

[0143] Figure 1 、 Figure 2It can be seen that the microstructure of the alloy of the present invention is uniform, well-formed, and has fine grains. The eutectic Si in the alloy structure appears as small dots and short rods, indicating a significant modification effect on the alloy. This is confirmed by the mechanical properties shown in Table 2. This shows that adding a certain proportion of V, Ga, and Sm to aluminum alloys can effectively improve the microstructure and enhance the overall mechanical properties of the alloy. Figure 3 3 is a comparison chart of the room temperature tensile mechanical properties of Example 4 and Comparative Example 6. Comparative Example 6 is a conventional commercial AlSi10MnMg alloy. It can be seen that the mechanical properties of the alloy of the present invention are more excellent.

[0144] The present invention adds certain proportions of V, Ga, and Sm to an aluminum alloy matrix, primarily improving the alloy's mechanical properties through synergistic strengthening. Sm and Sr produce a complex modification and grain refinement effect, while V and Ga effectively improve the alloy's toughness. Together, these three elements enhance the alloy's overall mechanical properties. Furthermore, this alloy reduces the impact of high iron content on alloy performance and can tolerate higher Fe contents, meeting the requirements for future production of automotive die-castings using recycled aluminum and complying with the requirements of green, low-carbon, and circular development.

[0145] The above embodiments of the present invention are described in detail. However, the above contents are only preferred embodiments of the present invention and should not be considered to limit the scope of the present invention. Any equivalent changes and improvements made within the scope of the present invention should still fall within the scope of this patent.

Claims

1. A heat-treatment-free aluminum alloy for new energy vehicle battery packs, characterized in that: The heat-treatment-free aluminum alloy has the following alloy components in percentage by mass: Si: 8.75-10.25wt.%, Mg: 0.03-0.27wt.%, Mn: 0.4-0.8wt.%, Cu: 0.01-0.11wt.%, Fe: 0.08-0.27wt.%, Ti: 0.06-0.13wt.%, Sr: 0.013-0.039wt.%, V: 0.015-0.07wt.%, Ga: 0.005-0.018wt.%, Sm: 0.003-0.15wt.%; the total amount of remaining impurities is less than or equal to 0.2wt.%, and the balance is Al.

2. The heat-treatment-free aluminum alloy for new energy vehicle battery pack according to claim 1, characterized in that: The heat-treatment-free aluminum alloy has the following alloy components in percentage by mass: Si: 8.75-9.5wt.%, Mg: 0.03-0.12wt.%, Mn: 0.4-0.6wt.%, Cu: 0.01-0.05wt.%, Fe: 0.08-0.12wt.%, Ti: 0.07-0.1wt.%, Sr: 0.013-0.03wt.%, V: 0.015-0.03wt.%, Ga: 0.005-0.01wt.%, Sm: 0.003-0.08wt.%; the total amount of other impurities is less than or equal to 0.2wt.%, and the balance is Al.

3. The heat-treatment-free aluminum alloy for new energy vehicle battery pack according to claim 1, characterized in that: The heat-treatment-free aluminum alloy has the following alloy components in percentage by mass: Si: 9.5-9.8wt.%, Mg: 0.12-0.20wt.%, Mn: 0.4-0.6wt.%, Cu: 0.03-0.07wt.%, Fe: 0.12-0.18wt.%, Ti: 0.07-0.1wt.%, Sr: 0.02-0.035wt.%, V: 0.03-0.05wt.%, Ga: 0.008-0.012wt.%, Sm: 0.08-0.12wt.%; the total amount of remaining impurities is less than or equal to 0.2wt.%, and the balance is Al.

4. The heat-treatment-free aluminum alloy for new energy vehicle battery pack according to claim 1, characterized in that: The heat-treatment-free aluminum alloy has the following alloy components in percentage by mass: Si: 9.8-10.25wt.%, Mg: 0.20-0.27wt.%, Mn: 0.4-0.6wt.%, Cu: 0.05-0.11wt.%, Fe: 0.18-0.27wt.%, Ti: 0.07-0.1wt.%, Sr: 0.028-0.039wt.%, V: 0.05-0.07wt.%, Ga: 0.013-0.018wt.%, Sm: 0.09-0.15wt.%; the total amount of remaining impurities is less than or equal to 0.2wt.%, and the balance is Al.

5. The heat-treatment-free aluminum alloy for new energy vehicle battery pack according to claim 1, characterized in that: The heat-treatment-free aluminum alloy has the following alloy components in the following mass percentages: Si: 9.15wt.%, Mg: 0.18wt.%, Mn: 0.5wt.%, Cu: 0.03wt.%, Fe: 0.11wt.%, Ti: 0.08wt.%, Sr: 0.035wt.%, V: 0.02wt.%, Ga: 0.008wt.%, Sm: 0.1wt.%; the total amount of remaining impurities is less than or equal to 0.2wt.%, and the balance is Al.

6. The heat-treatment-free aluminum alloy for new energy vehicle battery pack according to claim 1, characterized in that: The heat-treatment-free aluminum alloy has the following alloy components in the following mass percentages: Si: 9.83wt.%, Mg: 0.16wt.%, Mn: 0.5wt.%, Cu: 0.03wt.%, Fe: 0.25wt.%, Ti: 0.08wt.%, Sr: 0.038wt.%, V: 0.04wt.%, Ga: 0.015wt.%, Sm: 0.15wt.%; the total amount of remaining impurities is less than or equal to 0.2wt.%, and the balance is Al.

7. A method for preparing a heat-treatment-free aluminum alloy for a new energy vehicle battery pack, for preparing a heat-treatment-free aluminum alloy for a new energy vehicle battery pack according to any one of claims 1 to 6, characterized in that: The preparation method comprises the following steps: 1) Material preparation and preheating: Prepare the materials according to the alloy composition ratio, preheat the raw materials to be melted to 200-220℃ and dry them; 2) Melting: Raise the temperature to 740-760°C, melt pure aluminum and industrial silicon, then add Al-Cu master alloy, Al-Mn master alloy, Al-V master alloy, Al-Sr master alloy, Al-Ti master alloy, and Al-Sm master alloy respectively and melt them. After melting, cool to 700-720°C, add pure Mg, and press it into the bottom of the crucible with a tool to prevent Mg from burning on the liquid surface. Finally, wrap Ga in aluminum foil and press it into the bottom of the crucible with a tool to melt and stir. 3) Refining and degassing: Keep the temperature at 720-730℃, use rotary spray degassing equipment, and introduce nitrogen with refining agent powder into the melt for powder spray refining. The amount of refining agent added is 0.1-0.5%, and the melt refining and degassing is 8-10 minutes; 4) Ingot casting: The casting sample is subjected to spectral component analysis, and after the components are qualified, it is cast into an ingot; 5) Die-casting process: After melting the above aluminum alloy ingot, high-pressure die-casting is performed. The die-casting process is as follows: die-casting pressure 350-500 bar, injection speed 4-6 m / s, vacuum degree 10-40 mbar, die-casting temperature 680-710°C, and mold temperature 180-220°C. The die used for die-casting is a flat die close to the actual thickness of the battery pack. 6) Sampling test: The obtained casting flat plate mold is sampled and processed into rectangular cross-section test pieces by wire cutting, and the mechanical properties are tested using an electronic universal tensile testing machine.

8. The method for preparing a heat-treatment-free aluminum alloy for a new energy vehicle battery pack according to claim 7, wherein: The heat treatment-free aluminum alloy obtained by the preparation method has a tensile strength of 300-340 MPa, a yield strength of 145-175 MPa, and an elongation of 10-15% in the die-cast state.

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