A heat treatment free low pressure casting aluminum alloy, a preparation method and application thereof

Abstract

The application provides a heat treatment-free low-pressure casting aluminum alloy, a preparation method and application, and relates to the technical field of low-pressure casting.The heat treatment-free low-pressure casting aluminum alloy comprises the following components in percentage by weight: Si: 4.0-10.5%, Fe: 0-1.0%, Mn: 0.1-0.8%, Mg: 0-0.6%, La: 0.022-0.22%, V: 0.033-0.33%, B: 0.033-0.33%, and the balance of Al; the mass ratio of La, V and B is 2:3:3.The La, V and B elements can avoid the "silicon poisoning" of the high-silicon aluminum alloy, the nucleation efficiency of LaB6 and (V, Al)B2 particles will not be affected by the solute Si element, can directly serve as the heterogeneous nucleation point of alpha-Al, reduces the required supercooling degree of nucleation, improves the solidification efficiency of the alloy, promotes the refinement of the grains, and improves the mechanical properties of the alloy.

Description

Technical Field

[0001] This invention relates to the field of low-pressure casting technology, specifically to a heat-free low-pressure casting aluminum alloy, its preparation method, and its application. Background Technology

[0002] In an era of energy conservation, emission reduction, and low-carbon environmental protection, lightweighting has become a major theme in the global automotive industry. For every 100 kg reduction in weight of a gasoline-powered vehicle, fuel consumption can decrease by 0.3-0.6 liters per 100 kilometers; for every 10 kg reduction in weight of a pure electric vehicle, the driving range can increase by 2.5 kilometers. The carbon reduction effect brought about by weight reduction is considerable. Replacing steel with aluminum is one of the most effective methods for achieving automotive lightweighting, which has led to a continuous increase in the application of various components, particularly aluminum alloys, in automobiles.

[0003] Low-pressure casting is another aluminum alloy casting technology widely used in the automotive and aerospace industries, besides high-pressure casting. In addition to producing chassis structural components such as automotive wheel hubs, steering knuckles, and control arms, low-pressure casting can also be used to cast large, integrated castings, such as subframes and battery tray supports. The overall cost of equipment and molds for large, integrated low-pressure casting is only about one-tenth that of high-pressure casting, offering significant economic advantages. However, heat treatment of large, integrated low-pressure castings can lead to quality problems such as surface bubbles and product deformation, increasing the defect rate of aluminum castings and resulting in cost waste.

[0004] Currently, to prepare aluminum alloy castings that do not require heat treatment, modifiers such as strontium (Sr), scandium (Sc), and aluminum-titanium-boron (Al-Ti-B) alloys are typically added to the alloy composition. These modifiers have significant effects on improving the properties of aluminum alloys, such as refining grains and improving mechanical properties. However, in practice, the use of modifiers often leads to "silicon poisoning." This is because these elements may form stable compounds in alloys with high silicon content, resulting in uneven distribution of the silicon phase or grain coarsening, thus affecting the overall properties of the alloy.

[0005] Therefore, it is particularly important to develop a new type of heat-free aluminum alloy to avoid silicon poisoning and achieve the superior properties of aluminum alloy castings without compromising the quality of the silicon phase. Summary of the Invention

[0006] In view of the technical problems existing in the prior art, the present invention aims to provide a heat-free low-pressure casting aluminum alloy, its preparation method and application.

[0007] One objective of this invention is to provide a heat-free, low-pressure cast aluminum alloy, wherein the components of the heat-free, low-pressure cast aluminum alloy comprise, by weight percentage:

[0008] Si: 4.0-10.5%, Fe: 0-1.0%, Mn: 0.1-0.8%, Mg: 0-0.6%, La: 0.022-0.22%, V: 0.033-0.33%, B: 0.033-0.33%, balance Al;

[0009] The mass ratio of La, V, and B is 2:3:3.

[0010] Preferably, La, V, and B are added to the alloy in the form of Al-2La-3V-3B amorphous powder, with the Al-2La-3V-3B amorphous particle size being 20~30μm.

[0011] Preferably, the Al-2La-3V-3B amorphous powder is prepared by a spin-spinning method, the preparation method comprising:

[0012] Al-2La-3V-3B alloy foil was first prepared using a strip spinning machine, and then the alloy foil was ball-milled using a crusher to obtain Al-2La-3V-3B amorphous powder.

[0013] Preferably, the rotation speed of the tape spinning machine is 2200~2800 r / min, and the thickness of the prepared alloy foil tape is 20~30μm and the width is 1.8~2.2mm.

[0014] Preferably, the crusher ball mills the alloy foil belt under argon gas conditions, and the crusher speed is 2500~3500 r / min.

[0015] A second objective of this invention is to provide a method for preparing a heat-free, low-pressure cast aluminum alloy, the method comprising:

[0016] S1 alloy smelting: According to the composition, the raw materials are batched by weight percentage. First, pure aluminum ingots are melted. The temperature of the aluminum liquid is raised to 750~760℃. Pure silicon and aluminum-manganese alloy are added in sequence and kept for 25 minutes. The temperature of the aluminum liquid is adjusted to 720~730℃. Pure magnesium ingots are added and the mixture is melted to aluminum liquid I.

[0017] S2 Refining: Using the graphite rotary blowing method, refining agent and high-purity argon are added to aluminum liquid I at 720-730℃ to obtain aluminum liquid II;

[0018] S3 modification treatment: Adjust the temperature of aluminum liquid II to 710~720℃, and add Al-2La-3V-3B amorphous material to aluminum liquid II using the graphite rotary blowing method. After the addition is complete, continue to pass argon gas and stir for 5~8 minutes to obtain aluminum liquid III.

[0019] S4 low-pressure casting: The pressure is 500-1000 mbar, which produces aluminum alloy castings.

[0020] Preferably, the amount of refining agent used is 2% of the total weight of aluminum liquid II, the blowing time is 6 minutes, after refining, it is left to stand for 2-3 minutes, and the refining process is repeated twice.

[0021] Preferably, the refining agent includes one or more of Lande High Aluminum Alloy Refining Agent-AJ2A, Yili Aluminum Alloy Powdered Refining and Slag Removal Agent DLJ-5, or Promag Refining Agent.

[0022] Preferably, during the low-pressure casting process, when the molten aluminum III enters the mold, the temperature of the molten aluminum is 700~710℃, the temperature of the mold cavity is 300~350℃, and the temperature of the gate and the flow divider cone is 450~500℃.

[0023] The third objective of this invention is to provide an application of heat-free, low-pressure cast aluminum alloy in battery trays for new energy vehicles.

[0024] Beneficial effects of this invention:

[0025] This invention provides a heat-free, low-pressure cast aluminum alloy, the composition of which by weight percentage includes: Si: 4.0-10.5%, Fe: 0-1.0%, Mn: 0.1-0.8%, Mg: 0-0.6%, La: 0.022-0.22%, V: 0.033-0.33%, B: 0.033-0.33%, with the balance being Al; wherein the mass ratio of La, V, and B is 2:3:3.

[0026] On the one hand, the addition of La, V, and B elements can avoid the "silicon poisoning" phenomenon that occurs when using modifiers such as strontium (Sr), scandium (Sc), and aluminum-titanium-boron (Al-Ti-B) alloys with Si content greater than 8.0%. On the other hand, La reacts with B to form LaB6, and V reacts with Al and B to form (V,Al)B2. These LaB6 and (V,Al)B2 particles exhibit high stability in Al-Si alloy melts and have low lattice mismatch, meaning that a stable interface is formed between the particles and the matrix, reducing interfacial energy. This characteristic enhances the bonding strength between the particles and the matrix, improving the hardness and strength of the alloy. LaB6 and (V,Al)B2 particles directly serve as heterogeneous nucleation sites for α-Al, reducing the supercooling required for nucleation. This effect not only improves the solidification efficiency of the alloy but also promotes grain refinement. Furthermore, the nucleation efficiency of LaB6 and (V,Al)B2 particles is not affected by the solute Si element, thus exhibiting excellent grain refinement in high-silicon aluminum alloys to improve the mechanical properties of the alloy.

[0027] Due to the heterogeneous nucleation effect and grain refinement effect of the particles, the low-pressure cast aluminum alloy prepared by this invention can achieve high strength and toughness without heat treatment, with a yield strength of >160MPa, a tensile strength of >300MPa, and an elongation of >8%. It can replace steel as a battery tray material for new energy vehicles and meet the lightweight requirements of new energy vehicles. Detailed Implementation

[0028] According to a first aspect of this invention, a heat-free low-pressure cast aluminum alloy is provided, wherein the components of the heat-free low-pressure cast aluminum alloy comprise, by weight percentage:

[0029] Si: 4.0-10.5%, Fe: 0-1.0%, Mn: 0.1-0.8%, Mg: 0-0.6%, La: 0.022-0.22%, V: 0.033-0.33%, B: 0.033-0.33%, balance Al;

[0030] The mass ratio of La, V, and B is 2:3:3.

[0031] In this invention, the addition of La, V, and B elements avoids the "silicon poisoning" phenomenon that occurs in high-silicon aluminum alloys with a Si content greater than 8.0% when using modifiers such as strontium (Sr), scandium (Sc), and aluminum-titanium-boron (Al-Ti-B). La reacts with B to form LaB6, and V reacts with Al and B to form (V,Al)B2. These LaB6 and (V,Al)B2 particles exhibit high stability in Al-Si alloy melts and have low lattice mismatch, meaning that the particles form a stable interface with the matrix, reducing interfacial energy. This characteristic enhances the bonding strength between the particles and the matrix, improving the hardness and strength of the alloy. LaB6 and (V,Al)B2 particles directly serve as heterogeneous nucleation sites for α-Al, reducing the supercooling required for nucleation. This effect not only improves the solidification efficiency of the alloy but also promotes grain refinement. Furthermore, the nucleation efficiency of LaB6 and (V,Al)B2 particles is not affected by the solute Si element, thus exhibiting excellent grain refinement in high-silicon aluminum alloys to improve the mechanical properties of the alloy.

[0032] In this invention, the addition of Mn can transform the acicular iron-containing phase into the Chinese character-shaped or fine spherical α-Fe phase, greatly mitigating the adverse effects of Fe and improving the toughness and corrosion resistance of the alloy.

[0033] In this invention, the weight percentage of Si is, for example, 4.0%, 4.5%, 5.0%, 5.5%, 6.0%, 6.5%, 7.0%, 7.5%, 8.0%, 8.5%, 9.0%, 9.5%, 10.0%, or 10.5%; and the weight percentage of Fe is, for example, 0.03%, 0.05%, 0.10%, 0.20%, 0.30%, 0.40%, 0.50%, 0.60%, 0.70%, 0.80%, 0.90%, or 1.0%. The weight percentages of Mn are, for example, 0.10%, 0.15%, 0.2%, 0.25%, 0.30%, 0.35%, 0.40%, 0.45%, 0.50%, 0.55%, 0.60%, 0.65%, 0.70%, 0.75%, or 0.80%; the weight percentages of Mg are, for example, 0.05%, 0.10%, 0.15%, 0.2%, 0.25%, 0.30%, 0.35%, 0.40%, 0.45%, 0.5%. 0%, 0.55%, or 0.60%; the weight percentage of La is, for example, 0.022%, 0.025%, 0.030%, 0.035%, 0.040%, 0.045%, 0.050%, 0.055%, 0.060%, 0.065%, 0.070%, 0.075%, 0.080%, 0.085%, 0.090%, 0.095%, 0.10%, 0.11%, 0.15%, 0.17%, 0.19%, 0 0.20% or 0.22% by weight; the weight percentage of V is, for example, 0.033%, 0.066%, 0.099%, 0.132%, 0.165%, 0.198%, 0.231%, 0.264%, 0.297% or 0.33% by weight; the weight percentage of B is, for example, 0.033%, 0.066%, 0.099%, 0.132%, 0.165%, 0.198%, 0.231%, 0.264%, 0.297% or 0.33%.

[0034] In a preferred embodiment of the present invention, La, V and B are added to the alloy in the form of Al-2La-3V-3B amorphous powder, and the particle size of Al-2La-3V-3B amorphous powder is 20~30μm.

[0035] In this invention, amorphous materials have low melting points, are easy to cast, and possess a uniformly distributed microstructure and isotropic internal structure. When added to aluminum alloys in the form of amorphous powder, the aluminum alloys exhibit excellent mechanical and processing properties. The amorphous structure also possesses higher stability and uniformity, enabling better dispersion of added elements La, V, and B, effectively preventing the aggregation of added elements in the aluminum alloy, and avoiding the formation of localized high-concentration areas. This results in a more uniform composition distribution and superior performance improvement within the aluminum alloy.

[0036] In a preferred embodiment of the present invention, the Al-2La-3V-3B amorphous powder is prepared by a spin-spinning method, the preparation method comprising:

[0037] Al-2La-3V-3B alloy foil was first prepared using a strip spinning machine, and then Al-2La-3V-3B amorphous powder was obtained by ball milling the alloy foil using a crusher.

[0038] In this invention, the strip-spinning method can achieve rapid cooling and refinement by stripping. The LaB6 and (V,Al)B2 particles in the Al-2La-3V-3B amorphous material obtained by this method are more uniform and smaller in size, which can be quickly added into the aluminum alloy melt and distributed more evenly in the matrix, avoiding the problem of La element not being able to be added.

[0039] In a preferred embodiment of the present invention, the rotation speed of the strip spinning machine is 2200~2800 r / min, and the thickness of the prepared alloy foil strip is 20~30μm and the width is 1.8~2.2mm;

[0040] In this invention, the thickness of the prepared alloy foil strip is, for example, 20μm, 21μm, 22μm, 23μm, 24μm, 25μm, 26μm, 27μm, 28μm, 29μm or 30μm; and the width is, for example, 1.8mm, 1.9mm, 2.0mm, 2.1mm or 2.2mm.

[0041] In a preferred embodiment of the present invention, the crusher ball mills the alloy foil belt under argon gas conditions, and the crusher speed is 2500~3500 r / min.

[0042] In this invention, the crusher ball mills the alloy foil belt under argon gas conditions, and the crusher speed is 2500 r / min, 2600 r / min, 2700 r / min, 2800 r / min, 2900 r / min, 3000 r / min, 3100 r / min, 3200 r / min, 3300 r / min, 3400 r / min or 3500 r / min.

[0043] In this invention, the preparation of Al-2La-3V-3B amorphous powder by the belt-spinning method specifically includes:

[0044] First, cut pure aluminum ingots, Al-10La, Al-5V, and Al-3B master alloys into uniform small pieces and pack them into a custom-made quartz tube with a φ3mm hole at the bottom. Adjust the position of the quartz tube so that the master alloys are centered on the induction coil. Adjust the height of the quartz tube from the surface of the copper roller to 3-5mm, and polish the surface of the copper roller with fine sandpaper and metal polishing compound until it is shiny. Then, evacuate the chamber of the belt spinning machine to a 3×10⁻⁶ vacuum. -3The process involves creating a vacuum state (Pa); adjusting the copper roller speed to 2200~2800 r / min, controlling the pressure difference between the cavity and the spray gun to 20~40 Pa, starting the high-frequency induction power supply, adjusting the induction coil current to 20A, and adjusting the melting temperature to 1050℃; after the alloy is completely melted, maintaining the temperature for 30 min, then turning on the spray switch, using the pressure difference to spray the melt onto the copper roller, forming an alloy foil strip under rapid cooling at high speed, and collecting the alloy foil strip sample using a collecting cylinder. Under these working conditions, the alloy foil strip sample prepared by the strip spinning machine is generally about 20~30 μm thick and 1.8~2.2 mm wide. The alloy foil strip sample prepared by the strip spinning machine is placed in a crusher in an argon-filled glove box and ball-milled at a speed of 2500~3500 r / min for 15 min to remove the powder, thus obtaining Al-2La-3V-3B amorphous material.

[0045] According to a second aspect of this invention, a method for preparing a heat-treasure-free low-pressure cast aluminum alloy is provided, the method comprising:

[0046] S1 alloy smelting: According to the composition, the raw materials are batched by weight percentage. First, pure aluminum ingots are melted. The temperature of the aluminum liquid is raised to 750~760℃. Pure silicon and aluminum-manganese alloy are added in sequence and kept for 25 minutes. The temperature of the aluminum liquid is adjusted to 720~730℃. Pure magnesium ingots are added and the mixture is melted to aluminum liquid I.

[0047] S2 Refining: Using the graphite rotary blowing method, refining agent and high-purity argon are added to aluminum liquid I at 720-730℃ to obtain aluminum liquid II;

[0048] S3 modification treatment: Adjust the temperature of aluminum liquid II to 710~720℃, and add Al-2La-3V-3B amorphous material to aluminum liquid II using the graphite rotary blowing method. After the addition is complete, continue to pass argon gas and stir for 5~8 minutes to obtain aluminum liquid III.

[0049] S4 low-pressure casting: The pressure is 500-1000 mbar, which produces aluminum alloy castings.

[0050] In a preferred embodiment of the present invention, the amount of refining agent is 2% of the total weight of aluminum liquid II, the blowing time is 6 minutes, after refining, it is left to stand for 2 to 3 minutes, and the refining process is repeated twice.

[0051] In a preferred embodiment of the present invention, the refining agent includes one or more of Lande high aluminum alloy refining agent-AJ2A, Yili aluminum alloy powder spraying refining and slag removal agent DLJ-5, or Promag refining agent.

[0052] In this invention, the refining agent includes, for example, Lande high-alumina alloy refining agent-AJ2A, Yili aluminum alloy powder spraying refining and slag removal agent DLJ-5, Promag refining agent, Lande high-alumina alloy refining agent-AJ2A and Yili aluminum alloy powder spraying refining and slag removal agent DLJ-5, Lande high-alumina alloy refining agent-AJ2A and Promag refining agent, or a combination of Yili aluminum alloy powder spraying refining and slag removal agent DLJ-5 and Promag refining agent.

[0053] In a preferred embodiment of the present invention, during the low-pressure casting process, when the aluminum liquid III enters the mold, the temperature of the aluminum liquid is 700~710℃, the temperature of the mold cavity is 300~350℃, and the temperature of the gate and the flow divider cone is 450~500℃.

[0054] In this invention, the preparation method of heat-free low-pressure casting aluminum alloy specifically includes:

[0055] (1) Preparation of Al-2La-3V-3B amorphous powder

[0056] First, pure aluminum ingots, Al-10La, Al-5V, and Al-3B master alloys are cut into uniform small pieces and placed into a custom-made quartz tube with a φ3mm hole at the bottom. The position of the quartz tube is adjusted so that the master alloys are centered on the induction coil. The height of the quartz tube from the surface of the copper roller is adjusted to 4mm, and the surface of the copper roller is polished to a bright shine using fine sandpaper and metal polishing compound. Then, the chamber of the belt spinning machine is evacuated to a 3×10⁻⁶ vacuum. -3 The process involves a vacuum state (Pa); adjusting the copper roller speed to 2500 r / min, controlling the pressure difference between the cavity and the spray gun to 30 Pa, starting the high-frequency induction power supply, adjusting the induction coil current to 20 A, and adjusting the melting temperature to 1050℃; after the alloy is completely melted, maintaining the temperature for 30 min, then turning on the spray switch, using the pressure difference to spray the melt onto the copper roller, forming an alloy foil strip under rapid cooling at high speed, and collecting the alloy foil strip sample using a collecting cylinder. Under these working conditions, the alloy foil strip sample prepared by the strip spinning machine is generally about 25 μm thick and 2.0 mm wide. The alloy foil strip sample prepared by the strip spinning machine is placed in a crusher in an argon-filled glove box and ball-milled at 3000 r / min for 15 min to remove the powder, thus obtaining Al-2La-3V-3B amorphous material.

[0057] (2) Alloy smelting:

[0058] ①According to the material composition and weight percentage of each component of the heat-free low-pressure casting aluminum alloy material, industrial pure aluminum, industrial crystalline silicon, pure magnesium ingot, aluminum-manganese alloy, and Al-2La-3V-3B amorphous material are weighed as raw materials to prepare aluminum alloy.

[0059] ②Inspect the materials and tools to ensure they are clean and dry, then put the pure aluminum ingots into the crucible and heat them by electricity.

[0060] ③ After all the pure aluminum ingots have melted, the temperature is raised to 730℃ and the surface slag is removed.

[0061] ④ Heat the aluminum liquid to 750~760℃, add pure silicon, aluminum manganese and other alloys in batches, maintain for 25 minutes, and stir continuously during the process to accelerate the melting and diffusion of alloying elements.

[0062] ⑤ Adjust the temperature of the molten aluminum to 720~730℃, add pure magnesium ingots, and press them under the molten aluminum to melt.

[0063] ⑥ After all the above ingredients have melted, the aluminum liquid temperature is 730℃, and the mixture is stirred and the slag is removed.

[0064] (3) Melt treatment:

[0065] ① First refining: The temperature of the aluminum liquid is 720-730℃. The aluminum liquid is purified by graphite rotary jet blowing and powder blowing. The refining gas is high-purity argon. The amount of refining agent is 2% of the total weight of the aluminum liquid. The refining time is 6 minutes. After the refining is completed, let it stand for 2-3 minutes and remove the slag completely.

[0066] ② Second refining: The temperature of the aluminum liquid is 720-730℃. The aluminum liquid is purified by graphite rotary jet blowing and powder blowing. The refining gas is high-purity argon. The amount of refining agent is 2% of the total weight of the aluminum liquid. The refining time is 6 minutes. After the refining is completed, let it stand for 2-3 minutes and remove the slag completely.

[0067] ③ When the aluminum liquid temperature is 710~720℃, Al-2La-3V-3B amorphous powder is added by graphite rotary jetting. After the amorphous powder is added, argon gas is continuously passed through and the mixture is stirred for 5~8 minutes to accelerate the melting and diffusion of alloying elements.

[0068] ④ Test the composition of the molten aluminum. If it is qualified, let the molten aluminum stand for 20 minutes.

[0069] (4) Casting production

[0070] ① Mold preparation: The surface of the mold cavity needs to be cleaned. Place it in the mold heating furnace and heat it for 2 hours at a temperature of 250℃. After the mold comes out of the furnace, spray the heat-insulating coating on the aluminum liquid gating channel and riser. Spray the heat-conducting coating inside the product cavity. Then put it back into the mold heating furnace and keep it warm for 30 minutes.

[0071] ② Casting production: The temperature of the molten aluminum is controlled at 700~710℃. A professional mold heating device is used to heat the mold, controlling the temperature of the mold cavity at 300~350℃. The mold inlet and runner cone are heated to 450~500℃. When the mold is opened for the first time, all cooling water pipes are closed. When producing the fifth mold, two 20-mesh filters are placed at the riser, all cooling water pipes are opened, and the cooling water temperature is controlled at 28~30℃, the cooling water pressure at 0.4~0.55MPa, and the cooling gas pressure at 0.6~0.8MPa. The low-pressure casting machine is set to 700mbar, the pressurization time is 30s, and the pressure is held for 120s to obtain the low-pressure aluminum alloy casting.

[0072] ③ Post-processing: The produced low-pressure aluminum alloy castings are placed in a cooling water tank at 30~35℃ for 15 seconds and then removed. The gating gates and flash are then removed.

[0073] (5) Tensile test: After the treated low-pressure aluminum alloy casting is placed for 24 hours, test bars are prepared for tensile test.

[0074] The third objective of this invention is to provide an application of the heat-free, low-pressure cast aluminum alloy described above in the battery tray of new energy vehicles.

[0075] Example 1

[0076] (1) Alloy smelting:

[0077] ①According to the material composition and weight percentage of each component of the heat-free low-pressure casting aluminum alloy material, Si: 8.5%, Fe < 0.05%, Mn: 0.5%, Mg: 0.35%, La: 0.11%, V: 0.165% and B: 0.165%, with the balance being Al, industrial pure aluminum, industrial crystalline silicon, pure magnesium ingots, aluminum-manganese alloy, and Al-2La-3V-3B amorphous material are weighed as raw materials to prepare the aluminum alloy.

[0078] ②Inspect the materials and tools to ensure they are clean and dry, then put the pure aluminum ingots into the crucible and heat them by electricity.

[0079] ③ After all the pure aluminum ingots have melted, the temperature is raised to 730℃ and the surface slag is removed.

[0080] ④ Heat the aluminum liquid to 750~760℃, add pure silicon, aluminum manganese and other alloys in batches, maintain for 25 minutes, and stir continuously during the process to accelerate the melting and diffusion of alloying elements.

[0081] ⑤ Adjust the temperature of the molten aluminum to 720~730℃, add pure magnesium ingots, and press them under the molten aluminum to melt.

[0082] ⑥ After all the above ingredients have melted, the aluminum liquid temperature is 730℃, and the mixture is stirred and the slag is removed.

[0083] (2) Melt treatment:

[0084] ① First refining: The temperature of the aluminum liquid is 720-730℃. The aluminum liquid is purified by graphite rotary jet blowing and powder blowing. The refining gas is high-purity argon. The amount of refining agent is 2% of the total weight of the aluminum liquid. The refining time is 6 minutes. After the refining is completed, let it stand for 2-3 minutes and remove the slag completely.

[0085] ② Second refining: The temperature of the aluminum liquid is 720-730℃. The aluminum liquid is purified by graphite rotary jet blowing and powder blowing. The refining gas is high-purity argon. The amount of refining agent is 2% of the total weight of the aluminum liquid. The refining time is 6 minutes. After the refining is completed, let it stand for 2-3 minutes and remove the slag completely.

[0086] ③ When the aluminum liquid temperature is 710~720℃, Al-2La-3V-3B amorphous powder is added by graphite rotary jetting. After the amorphous powder is added, argon gas is continuously passed through and the mixture is stirred for 5-8 minutes to accelerate the melting and diffusion of alloying elements.

[0087] ④ Test the composition of the molten aluminum. If it is qualified, let the molten aluminum stand for 20 minutes.

[0088] (3) Casting production

[0089] ① Mold preparation: The surface of the mold cavity needs to be cleaned. Place it in the mold heating furnace and heat it for 2 hours at a temperature of 250℃. After the mold comes out of the furnace, spray the heat-insulating coating on the aluminum liquid gating channel and riser. Spray the heat-conducting coating inside the product cavity. Then put it back into the mold heating furnace and keep it warm for 30 minutes.

[0090] ② Casting production: The temperature of the molten aluminum is controlled at 700~710℃. A professional mold heating device is used to heat the mold, controlling the temperature of the mold cavity at 300~350℃. The mold inlet and runner cone are heated to 450~500℃. When the mold is opened for the first time, all cooling water pipes are closed. When producing the fifth mold, two 20-mesh filters are placed at the riser, all cooling water pipes are opened, and the cooling water temperature is controlled at 28~30℃, the cooling water pressure at 0.4~0.55MPa, and the cooling gas pressure at 0.6~0.8MPa. The low-pressure casting machine is set to 700mbar, the pressurization time is 30s, and the pressure is held for 120s to obtain the low-pressure aluminum alloy casting.

[0091] ③ Post-processing: The produced low-pressure aluminum alloy castings are placed in a cooling water tank at 30~35℃ for 15 seconds and then removed. The gating gates and flash are then removed.

[0092] (5) Tensile test: After the treated low-pressure aluminum alloy casting is placed for 24 hours, test bars are prepared for tensile test.

[0093] Example 2

[0094] ①According to the material composition and weight percentage of each component of the heat-free low-pressure casting aluminum alloy material, Si: 6.0%, Fe < 0.05%, Mn: 0.35%, Mg: 0.35%, La: 0.022%, V: 0.033% and B: 0.033%, with the balance being Al, industrial pure aluminum, industrial crystalline silicon, pure magnesium ingots, aluminum-manganese alloy, and Al-2La-3V-3B amorphous material are weighed as raw materials to prepare the aluminum alloy.

[0095] The remaining steps and parameters are the same as in Example 1.

[0096] Example 3

[0097] According to the material composition and weight percentage of each component of the heat-free low-pressure casting aluminum alloy material, Si: 10.5%, Fe < 0.05%, Mn: 0.60%, Mg: 0.35%, La: 0.22%, V: 0.33% and B: 0.33%, with the balance being Al, industrial pure aluminum, industrial crystalline silicon, pure magnesium ingots, aluminum-manganese alloy, and Al-2La-3V-3B amorphous material were weighed as raw materials for aluminum alloy batching.

[0098] The remaining steps and parameters are the same as in Example 1.

[0099] Comparative Example 1

[0100] According to the material composition and weight percentage of each component in the heat-free low-pressure casting aluminum alloy material, Si: 8.5%, Fe < 0.05%, Mn: 0.50% and Mg: 0.35%, with the balance being Al, industrial pure aluminum, industrial crystalline silicon, pure magnesium ingots, and aluminum-manganese alloy are weighed as raw materials for aluminum alloy batching.

[0101] The remaining steps and parameters are the same as in Example 1.

[0102] Comparative Example 2

[0103] According to the material composition and weight percentage of each component of the heat-free low-pressure casting aluminum alloy material, Si: 8.5%, Fe < 0.05%, Mn: 0.50%, Mg: 0.35%, Sr: 0.10%, and the balance being Al, aluminum alloy is batched.

[0104] The remaining steps and parameters are the same as in Example 1.

[0105] Comparative Example 3

[0106] According to the material composition and weight percentage of each component of the heat-free low-pressure casting aluminum alloy material, Si: 8.5%, Fe < 0.05%, Mn: 0.50%, Mg: 0.35%, Al-Ti-B: 0.10%, and the balance being Al, the aluminum alloy is batched.

[0107] The remaining steps and parameters are the same as in Example 1.

[0108] Comparative Example 4

[0109] A common commercial A356 low-pressure casting aluminum alloy material is prepared by batching aluminum alloy according to the material composition and weight percentage of each component of the heat-free low-pressure casting aluminum alloy material: Si: 7.0%, Fe < 1.5%, Ti: 0.10% and Mg: 0.30%, with the balance being Al.

[0110] The remaining steps and parameters are the same as in Example 1.

[0111] Performance testing

[0112] Performance testing was conducted in accordance with GB / T 228.1 "Metallic materials - Tensile testing - Part 1: Test methods at room temperature - Tensile testing of metallic materials".

[0113] Table 1 Mechanical property testing of die-cast aluminum alloys in Examples 1-3 and Comparative Examples 1-4

[0114]

Claims

1. A heat-treasure-free low-pressure cast aluminum alloy, characterized in that, The heat-free, low-pressure cast aluminum alloy components, by weight percentage, include: Si: 4.0~10.5%, Fe: 0.03~1.0%, Mn: 0.1~0.8%, Mg: 0.05~0.6%, La: 0.022~0.22%, V: 0.033~0.33%, B: 0.033~0.33%, balance Al; The mass ratio of La, V, and B is 2:3:

3.

2. The heat-free, low-pressure cast aluminum alloy as described in claim 1, characterized in that, The La, V, and B are added to the alloy in the form of Al-2La-3V-3B amorphous powder, with the Al-2La-3V-3B amorphous particle size being 20~30μm.

3. The heat-free, low-pressure cast aluminum alloy as described in claim 2, characterized in that, The preparation method of the Al-2La-3V-3B amorphous powder includes: firstly, preparing Al-2La-3V-3B alloy foil by spinning, and then ball milling the alloy foil with a crusher to obtain Al-2La-3V-3B amorphous powder.

4. The heat-free, low-pressure cast aluminum alloy as described in claim 3, characterized in that, The Al-2La-3V-3B alloy foil strip was prepared using a strip spinning machine with a speed of 2200~2800 r / min. The prepared alloy foil strip had a thickness of 20~30μm and a width of 1.8~2.2mm.

5. The heat-free, low-pressure cast aluminum alloy as described in claim 3, characterized in that, The crusher ball mills the alloy foil belt under argon gas conditions, and the crusher speed is 2500~3500 r / min.

6. A method for preparing a heat-free, low-pressure cast aluminum alloy as described in any one of claims 1 to 5, characterized in that, The preparation method includes: S1 alloy smelting: According to the composition, the raw materials are batched by weight percentage. First, pure aluminum ingots are melted. The temperature of the aluminum liquid is raised to 750~760℃. Pure silicon and aluminum-manganese alloy are added in sequence and kept for 25 minutes. The temperature of the aluminum liquid is adjusted to 720~730℃. Pure magnesium ingots are added and the mixture is melted to aluminum liquid I. S2 Refining: Using the graphite rotary blowing method, refining agent and high-purity argon are added to aluminum liquid I at 720-730℃ to obtain aluminum liquid II; S3 modification treatment: Adjust the temperature of aluminum liquid II to 710~720℃, and add Al-2La-3V-3B amorphous material to aluminum liquid II using the graphite rotary blowing method. After the addition is complete, continue to pass argon gas and stir for 5~8 minutes to obtain aluminum liquid III. S4 low-pressure casting: The pressure is 500-1000 mbar, which produces aluminum alloy castings.

7. The method for preparing heat-free low-pressure cast aluminum alloy as described in claim 6, characterized in that, The amount of refining agent used is 2% of the total weight of aluminum liquid II, the blowing time is 6 minutes, after refining, let it stand for 2-3 minutes, and the refining process is repeated twice.

8. The method for preparing heat-free low-pressure cast aluminum alloy as described in claim 6, characterized in that, The refining agent includes one or more of the following: Lande High Aluminum Alloy Refining Agent-AJ2A, Yili Aluminum Alloy Powdered Refining and Slag Removal Agent DLJ-5, or Promag Refining Agent.

9. The method for preparing heat-free low-pressure cast aluminum alloy as described in claim 6, characterized in that, During the low-pressure casting process, when the molten aluminum III enters the mold, the temperature of the molten aluminum is 700~710℃, the temperature of the mold cavity is 300~350℃, and the temperature of the gate and the flow divider cone is 450~500℃.

10. The application of a heat-free, low-pressure cast aluminum alloy as described in any one of claims 1 to 5 in a battery tray for new energy vehicles.

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