Aluminum alloy and method of making same, method of crush testing aluminum alloy

Abstract

This invention relates to the field of alloy technology, and particularly to an aluminum alloy and its preparation method, as well as a crush test method for the aluminum alloy. The aluminum alloy, by mass percentage, comprises: La, 0.08% to 0.15%; Si, 0.55% to 0.65%; Mg, 0.48% to 0.58%; Fe, 0.15% to 0.25%; Mn, 0.15% to 0.25%; Cr, 0.06% to 0.12%; Ti, 0.05% to 0.10%; with the balance being Al. The addition of these elements improves the strength and plasticity of the aluminum alloy, enhances its overall performance, and improves its crush resistance.

Description

Technical Field

[0001] This invention relates to the field of alloy technology, and in particular to an aluminum alloy and its preparation method, as well as a crush test method for aluminum alloys. Background Technology

[0002] Aluminum alloys are one of the most widely used metal structural materials in industry.

[0003] During a collision, aluminum alloy structures typically need to be able to resist external impact forces. Summary of the Invention

[0004] The main objective of this invention is to provide an aluminum alloy that improves the crush resistance of aluminum alloys.

[0005] To achieve the above objectives, the present invention provides an aluminum alloy, comprising, by weight percentage:

[0006] La, 0.08% to 0.15%;

[0007] Si, 0.55% to 0.65%;

[0008] Mg, 0.48% to 0.58%;

[0009] Fe, 0.15% to 0.25%;

[0010] Mn, 0.15% to 0.25%;

[0011] Cr, 0.06% to 0.12%;

[0012] Ti, 0.05% to 0.10%;

[0013] The margin is Al.

[0014] Adding La within the above range can improve the deoxidation and impurity purification effects, improve the fluidity of aluminum alloy liquid, refine aluminum alloy grains, make the structure uniform, and improve the mechanical properties of aluminum alloy.

[0015] The addition of appropriate amounts of silicon (Si) can improve the casting performance and corrosion resistance of aluminum alloys. Improved casting performance leads to enhanced casting quality and performance. The addition of appropriate amounts of magnesium (Mg) improves the plasticity and crushability of aluminum alloys. Fe and Mn elements increase the recrystallization temperature of aluminum alloys and inhibit recrystallized grain growth. Controlling Fe content within the aforementioned range mitigates the problem of excessive Fe content negatively impacting product surface quality, while controlling Mn content within the same range mitigates the problem of excessive Mn content leading to the formation of coarse intermetallic compound primary crystals. Cr element inhibits recrystallization nucleation and growth. Ti element refines the casting microstructure. Through the addition of these elements, the strength and plasticity of aluminum alloys are improved, enhancing overall performance and crushability.

[0016] Understandably, the finer the grains, meaning the more grains per unit volume, the more grain boundaries there are, and the more tortuous the grain boundaries, the greater the resistance to dislocations, and the higher the strength. At the same time, under the same amount of plastic deformation, the deformation is distributed within more grains, resulting in more uniform deformation; fewer dislocations are piled up in each grain, reducing the chance of cracking due to stress concentration, and allowing it to withstand a greater amount of deformation before fracture.

[0017] Optionally, the mass percentage of La is 0.1% to 0.15%;

[0018] And / or, the mass percentage of Si is 0.57% to 0.62%;

[0019] And / or, the mass percentage of Mg is 0.5% to 0.55%;

[0020] And / or, the mass percentage of Fe is 0.15% to 0.2%;

[0021] And / or, the mass percentage of Mn is 0.19% to 0.24%;

[0022] And / or, the mass percentage of Cr is 0.08% to 0.12%;

[0023] And / or, the mass percentage of Ti is 0.06% to 0.10%;

[0024] And / or, the mass percentage of Zn in the aluminum alloy is ≤0.05%;

[0025] And / or, the mass percentage of Cu in the aluminum alloy is ≤0.05%.

[0026] To further improve the strength and plasticity of aluminum alloys, enhance their overall performance, and improve their crushability, the mass percentages of La are controlled as follows: 0.1% to 0.15%; Si: 0.57% to 0.62%; Mg: 0.5% to 0.55%; Fe: 0.15% to 0.2%; Mn: 0.19% to 0.24%; Cr: 0.08% to 0.12%; Ti: 0.06% to 0.10%; Zn: ≤0.05%; Cu: ≤0.05%. It is understood that higher Zn and Cu mass percentages increase strength, but increased strength reduces the crushability of the aluminum alloy. Furthermore, Zn and Cu are relatively expensive; therefore, their mass percentages are controlled within the aforementioned ranges.

[0027] This application also provides a method for preparing an aluminum alloy, comprising:

[0028] Prepare the formulation components of the aluminum alloy to obtain the raw materials;

[0029] The raw materials are melted, refined, degassed, slag removed, and cast to obtain aluminum alloy castings.

[0030] In the process of preparing aluminum alloys, the various components of the aluminum alloy are prepared to obtain raw materials; the raw materials are melted, refined, degassed, slag removed, and cast to obtain aluminum alloy castings.

[0031] Optionally, after melting, refining, degassing, removing slag, and casting the raw materials to obtain aluminum alloy castings, the process further includes the following steps:

[0032] The aluminum alloy casting is homogenized under the following conditions: holding temperature 575℃±10℃, holding time 6h to 8h.

[0033] Homogenization treatment, also known as homogenization annealing, is a process in which an alloy ingot is heated to near the unequilibrium solidus temperature and held at that temperature for a relatively long time, and then slowly cooled to room temperature. Its purpose is to eliminate or reduce the inhomogeneity of the intracrystalline chemical composition and structure of the alloy through the diffusion of alloy element atoms, improve the internal structure of the ingot, eliminate residual stress in the ingot, improve the machinability of the ingot, and at the same time improve plasticity, reduce deformation resistance, and improve the hot working properties of the alloy.

[0034] To improve the properties of the alloy, after obtaining the aluminum alloy casting, the alloy casting is also homogenized. Homogenization can improve the internal structure of the alloy, reduce residual stress, improve machinability, increase plasticity, reduce deformation resistance, and improve the processing performance of the alloy.

[0035] To improve the performance of aluminum alloy castings, the homogenization treatment was carried out at a holding temperature of 575℃±10℃ for 6 to 8 hours.

[0036] It is understandable that the diameter of aluminum alloy castings ranges from 90mm to 500mm, and the corresponding holding time is 6h to 8h. The larger the diameter, the longer the holding time, which improves the internal structure of the aluminum alloy rod, eliminates residual stress, and dissolves the primary strengthening phase Mg2Si.

[0037] Optionally, after homogenizing the aluminum alloy casting, a cooling step is further included, wherein the cooling conditions are: air cooling to greater than or equal to 200°C and less than 250°C, followed by water cooling to room temperature.

[0038] Room temperature refers to the current ambient temperature, which varies depending on the location, season, or workshop. There is no specific limit; for example, room temperature can range from 10°C to 50°C.

[0039] This application adopts a mist cooling method, which refers to generating atomized water vapor through a mist cooling device and spraying the atomized water vapor onto the aluminum alloy casting that needs to be cooled. This cooling method has a fast cooling speed, which is beneficial to preserving the microstructure of the aluminum alloy casting at high temperature. Rapid cooling can also shorten the processing time.

[0040] Optionally, the steps of melting, refining, degassing, removing slag, and casting the raw materials to obtain aluminum alloy castings include:

[0041] At a melting temperature of 710°C to 750°C, Al is melted in a melting furnace, and Fe, Mn, Cr, Si, and La are added and melted, and Mg is added and melted to obtain aluminum liquid A;

[0042] The aluminum liquid A is refined, degassed, and slag removed.

[0043] Aluminum-titanium wire is added and melted to obtain molten aluminum (B);

[0044] The aluminum liquid B is melted and cast.

[0045] The steps of melting, refining, degassing, removing slag, and casting the raw materials to obtain aluminum alloy castings include: melting Al in a melting furnace at a melting temperature of 710℃ to 750℃, adding Fe, Mn, Cr, Si, and La, and then adding Mg to obtain aluminum liquid A; refining, degassing, and removing slag from aluminum liquid A; adding aluminum-titanium wire to obtain aluminum liquid B; and casting aluminum liquid B.

[0046] This application employs a step-by-step feeding method for the raw materials into the melting furnace. The order in which the raw materials are fed not only affects the melting efficiency and alloy consumption but also directly impacts the quality of the molten aluminum alloy. By adopting the above-described feeding steps, melting efficiency can be improved and alloy consumption reduced.

[0047] Understandably, when charging the smelting furnace, small pieces or thin sheets of scrap are charged first, aluminum ingots and large pieces are charged in the middle, and master alloys are charged last. Easily oxidized master alloys are charged in the lower and middle layers. The charged materials should be evenly distributed in the molten pool to prevent uneven distribution. Charging small pieces or thin sheets in the lower layer of the molten pool reduces burn-off and protects the furnace from direct impact damage from large pieces. The Al-Mn master alloy added in this scheme has a relatively high melting point (750℃-800℃) and should be charged in the upper layer. The higher temperature in the upper part of the furnace facilitates melting and allows sufficient time for diffusion, resulting in a uniform distribution of the master alloy and facilitating control of the melt composition.

[0048] The furnace charge is leveled, ensuring a relatively uniform melting rate throughout, which prevents localized overheating caused by uneven weight distribution. This charging method not only reduces burn-off but also increases the melting rate, facilitating composition control. Furthermore, it minimizes temperature fluctuations within the furnace, provides good protection for the furnace bottom, and helps extend the furnace's lifespan.

[0049] Optionally, the refining conditions are as follows: refining is carried out using argon gas and a sodium-free refining agent, with the amount of sodium-free refining agent used being 1.8 kg to 2.2 kg per ton of Al; the refining temperature is 730°C to 750°C, and the refining time is 15 min to 20 min.

[0050] And / or, the degassing condition is: online degassing using a dual-rotor degassing box;

[0051] And / or, the slag removal condition is: slag removal is performed by using a filter plate.

[0052] Optionally, the casting conditions are as follows: the aluminum B liquid is formed and cast using a hot-top casting machine, and during the casting process, the temperature of the aluminum B liquid reaching the casting pan is controlled at 700°C to 720°C, and the casting speed of the casting machine is 100 mm / min to 130 mm / min.

[0053] Refining is the process of removing impurities from the molten aluminum. It's understood that increased slag and gas content in the molten aluminum alters its chemical composition, leading to pinholes, oxide inclusions, shrinkage porosity, and substandard chemical composition in the castings, thus affecting casting quality. To obtain qualified aluminum alloy castings, the aforementioned refining conditions are employed. In-furnace refining primarily involves using granular refining agents to adsorb inclusions and float them to the surface of the molten aluminum, making the molten aluminum purer and reducing defects such as porosity, inclusions, and looseness in the aluminum rods.

[0054] It is understood that the sodium-free refining agent in this application is not specifically limited, and may include, but is not limited to, calcium fluoride, potassium fluorosilicate, potassium chloride, lithium chloride, magnesium chloride, calcium oxide, titanium dioxide powder, and carbon powder.

[0055] The degassing conditions are: online degassing using a dual-rotor degassing box.

[0056] During the melting process, aluminum alloys absorb hydrogen gas, for example, through reactions between the molten aluminum alloy and water vapor. Hydrogen absorption leads to pinholes in the aluminum alloy castings, reducing their airtightness and mechanical properties. To improve the performance of aluminum alloy castings, hydrogen is removed through a degassing process. Refining aluminum alloys using argon gas injection, for example, employing online degassing with a dual-rotor degassing box to rotaryly inject argon gas, can remove hydrogen and inclusions, purify the molten aluminum, and eliminate pinholes in the castings.

[0057] Its working principle is that when the motor drives the rotor to rotate (usually at a speed of 380-450 rpm), argon gas (flow rate of 0.5 m³ / min) is released. 3 / hour -1.5m 3 The hydrogen is broken into very small bubbles (per hour). The presence of these small bubbles reduces the concentration of hydrogen in the molten aluminum and its surface partial pressure, thereby reducing the concentration of hydrogen in the molten aluminum. This causes the hydrogen to be carried out of the molten aluminum surface by argon gas and burned off on the surface.

[0058] Furthermore, as argon gas bubbles move from the bottom of the molten aluminum to the surface, the hydrogen dissolved in the aluminum changes from a dissolved state to an adsorbed state upon encountering the argon-aluminum interface. Gas atoms in the adsorbed layer react to generate hydrogen molecules, which rise to the surface of the molten aluminum and burn off as the bubbles grow larger. Additionally, as the argon gas bubbles move from the bottom of the molten aluminum to the surface, suspended particles in the aluminum are agitated, colliding, aggregating, and growing. When these inclusions reach a certain size, they may collide with rising bubbles, be captured, and brought to the surface, thus achieving slag removal. This reduces defects such as porosity, slag inclusions, and looseness in aluminum rods.

[0059] The conditions for slag removal are: using a filter plate for slag removal.

[0060] During the melting process, aluminum alloy raw materials absorb gas and oxidize, forming oxide inclusions inside or on the surface of the molten aluminum alloy. These inclusions are easily adsorbed by gases within the molten aluminum alloy, making it difficult for these gases to escape. The presence of both gas and oxide inclusions in the molten aluminum alloy leads to defects such as porosity and inclusions in the aluminum alloy castings. To improve the performance of aluminum alloy castings, slag removal processes are used to remove slag from the molten aluminum alloy. For example, a two-stage filter plate with a mesh size of 40 to 60 mesh can be used.

[0061] The casting conditions are as follows: the aluminum B liquid is formed and cast by a hot-top casting machine. During the casting process, the temperature of the aluminum B liquid reaching the casting pan is controlled at 700℃ to 720℃, and the casting speed of the casting machine is 100mm / min to 130mm / min.

[0062] Melting and casting refers to the process of shaping molten aluminum alloy into a solid alloy of a specific shape under certain conditions. For example, molten aluminum alloy is poured into a mold for casting; the mold is equipped with a water-cooling system to control the cooling rate during casting, and argon gas is used for protection during pouring. The mold is then cooled and solidified to obtain the molten aluminum alloy casting. The aforementioned melting and casting conditions are used to eliminate problems such as uneven microstructure, coarse grains, and compositional segregation in molten aluminum alloy castings.

[0063] Optionally, the average grain size range of the as-cast microstructure of the aluminum alloy obtained after melting and casting is ≤150 μm.

[0064] As-cast microstructure refers to the microstructure formed when a metallic (mostly alloy) material transforms from a molten metal into a solid during the smelting process. By applying the aforementioned process conditions, the average grain size of the as-cast aluminum alloy is within the range described above. Fine as-cast grains contribute to improved strength and plasticity of the aluminum alloy, and enhance its crushing performance during impact and extrusion processes.

[0065] Optionally, after melting, refining, degassing, removing slag, and casting the raw materials to obtain aluminum alloy castings, the process further includes:

[0066] The aluminum alloy casting is heated, extruded, quenched, and cut to obtain an aluminum alloy profile.

[0067] Profiles are objects with a certain geometric shape made of iron or steel and materials with a certain strength and toughness (such as plastics, aluminum, glass fiber, etc.) through processes such as rolling, extrusion, and casting.

[0068] To obtain aluminum alloy profiles with suitable dimensions and performance, the prepared aluminum alloy castings can be heated, extruded, quenched, and cut to obtain aluminum alloy profiles.

[0069] The heating step softens the aluminum alloy casting, facilitating subsequent extrusion deformation. The extrusion step involves hot-extending the heated aluminum alloy casting using an extrusion press to shape it into a specific form. Quenching is a metal heat treatment process that involves heating a metal workpiece to a suitable temperature and holding it for a period of time, followed by rapid cooling in a quenching medium. Quenching can improve the properties of aluminum alloys. Cutting refers to using cutting tools to cut the aluminum alloy into profiles of a specific size.

[0070] Optionally, the step of heating, extruding, quenching, and cutting the aluminum alloy casting to obtain the aluminum alloy profile includes:

[0071] Aluminum alloy castings are heated, extruded, quenched, stretched, straightened, and cut to obtain aluminum alloy profiles.

[0072] Tensile straightening refers to the process of clamping both ends of an aluminum alloy with two clamping devices and generating tensile force to cause plastic deformation of the aluminum alloy, thereby achieving the purpose of tension straightening.

[0073] Stretching and straightening can improve the internal stress of aluminum alloys, thereby improving their strength, resistance to stress corrosion, and structural dimensional stability.

[0074] Optionally, the steps of heating, extruding, quenching, and cutting the aluminum alloy casting to obtain the aluminum alloy profile include:

[0075] The aluminum alloy casting is heated, extruded, quenched, cut, and aged to obtain an aluminum alloy profile.

[0076] Aging is a heat treatment process in which supersaturated solid solution alloys are heated to room temperature or held at a certain temperature to enrich solute components or precipitate a second phase. Aging at room temperature is called natural aging. Aging at temperatures above room temperature is called artificial aging. The phenomenon of strengthening by the precipitation of a second phase during aging is called age strengthening. Aging below or above the peak strengthening temperature is called sub-aging and over-aging treatment, respectively.

[0077] To improve the toughness of aluminum alloys and address their tendency to fracture during extrusion, an aging treatment is performed on the aluminum alloy after cutting. This process eliminates residual stress within the aluminum alloy profile, stabilizes its shape, dimensions, strength, and hardness, and ultimately enhances the overall mechanical properties of the aluminum alloy profile.

[0078] Optionally, the heating and extrusion conditions for the aluminum alloy casting are as follows: heating the extrusion die to 470°C to 500°C and holding it at that temperature for 4 hours to 12 hours, and then heating the aluminum alloy casting to 460°C to 500°C and extruding it at an extrusion speed of 1.5 mm / s to 5.0 mm / s.

[0079] In order to soften the aluminum alloy castings to facilitate subsequent extrusion deformation and to achieve a certain solution treatment effect, the aluminum alloy castings are heated to a temperature of 460℃ to 500℃.

[0080] To refine the extruded microstructure grains, the extrusion conditions are as follows: heating the extrusion die to 470°C to 500°C and holding it at that temperature for 4 to 12 hours; heating the aluminum alloy casting to 460°C to 500°C and extruding at an extrusion speed of 1.5 mm / s to 5.0 mm / s.

[0081] Optionally, the quenching conditions are: quenching temperature range of 500℃ to 535℃, and cooling intensity ≥8℃ / s;

[0082] And / or, the quenching method includes spray cooling or water cooling.

[0083] To ensure the strength and toughness of the profile, the quenching temperature range is 500℃ to 535℃, and the cooling intensity is ≥8℃ / s.

[0084] The quenching methods include spray cooling or water cooling.

[0085] Spray cooling can be an online quenching method. Online quenching refers to quenching while extruding, while offline quenching is quenching after extrusion. This application does not limit the quenching method, but online quenching is preferred because it can reduce costs and improve efficiency.

[0086] The quenching method can be spray cooling or water cooling. Among them, water cooling is preferred according to the profile structure. Water cooling has high cooling intensity, good cooling effect and short cooling time. This process can inhibit grain growth and help improve the performance of aluminum alloy.

[0087] Understandably, the quenching temperature at the discharge port is controlled by a combination of heating temperature and extrusion speed. To ensure production efficiency, the extrusion speed is generally increased as much as possible within the limits allowed by the extrusion die. The faster the speed, the higher the frictional heat generated between metals and between metals and the die (extrusion temperature rise), and the higher the discharge port temperature will be. Excessive temperature can lead to coarse grains in the profile structure and even cracking. Therefore, it is necessary to appropriately reduce the heating temperature of the aluminum alloy casting to balance the quenching temperature at the discharge port. For this purpose, the heating temperature is 460℃ to 500℃.

[0088] Optionally, the average grain size of the extruded microstructure ranges from 80 μm to 120 μm.

[0089] Through the above steps, the average grain size of the extruded microstructure in this application meets the aforementioned range. Refined extruded microstructure grains help improve the strength and plasticity of the aluminum alloy, and enhance its crushing performance during impact extrusion.

[0090] Optionally, during the stretching and straightening process, the elongation rate of the stretch is 0.5% to 1.3%.

[0091] Stretch straightening can improve the internal stress of aluminum alloys. To improve performance, the elongation rate during stretch straightening is 0.5 to 1.3 times. Elongation rate = (length after stretching - length before stretching) / length before stretching * 100%. Stretch straightening can eliminate longitudinal shape irregularities and reduce residual stress. The elongation rate range is 0.5% to 1.3%. If the elongation rate is too low, it will not have the effect of straightening and eliminating internal stress. If the elongation rate is too high, it will cause a decrease in the plasticity of the profile, orange peel surface, local thinning, or dimensional deviations from tolerance.

[0092] Optionally, the aging treatment conditions include over-aging treatment, wherein the over-aging treatment temperature is 205°C to 210°C and the holding time is 4.5h to 6h.

[0093] To improve the toughness of aluminum alloys, aging treatment conditions include over-aging, with over-aging temperatures ranging from 205℃ to 210℃ and holding times ranging from 4.5h to 6h. Under certain temperature conditions, when the aging holding time exceeds the peak aging time or the holding temperature exceeds the peak holding temperature, the precipitated phases inside the material begin to grow, and the spacing increases. Macroscopically, this manifests as a decrease in the material's strength, but an improvement in its ductility and toughness.

[0094] This application also provides a method for testing the crushability of aluminum alloys, including:

[0095] The aluminum alloy is fixed to the supporting structure;

[0096] The impact member is controlled to extrude along the surface of the aluminum alloy profile, the impact member applies extrusion force to the aluminum alloy in a first direction, and the support structure is used to provide constraint reaction force to the aluminum alloy; the aluminum alloy includes the aluminum alloy as described above, or the aluminum alloy includes the aluminum alloy obtained by the method for preparing the aluminum alloy as described above.

[0097] Crushing performance refers to a test that uses an impactor with a certain kinetic energy to impact and crush a material of a certain shape in a certain direction to study the deformation of the material.

[0098] To test the crushing performance of aluminum alloys, the aluminum alloy is fixed to a supporting structure. An impactor is controlled to compress along the surface of the aluminum alloy profile, applying compressive force to the aluminum alloy in a first direction. The supporting structure provides constraint reaction force to the aluminum alloy. In this way, the aluminum alloy is sandwiched between the supporting structure and the impactor and subjected to compressive force. After the aluminum alloy is subjected to compressive force, its shape can be observed to evaluate its crushing performance.

[0099] Optionally, in the step of fixing the aluminum alloy to the support structure, the support structure includes a platform and a support plate erected on the platform, the aluminum alloy is disposed on the platform and abuts against the support plate, and the aluminum alloy is fixed to the platform and / or the support plate.

[0100] To effectively secure the aluminum alloy, the support structure includes a platform and a support plate erected on the platform. The two surfaces of the aluminum alloy can rest against the platform and the support plate, improving the stability of the aluminum alloy installation. This is especially important when the aluminum alloy has an irregular shape and is difficult to secure; the limiting effect of the two surfaces enhances the installation stability of the aluminum alloy.

[0101] Optionally, in the step of controlling the extrusion of the impact member along the surface of the aluminum alloy, the extrusion direction of the impact member is toward the platform or the support plate.

[0102] To test the crushing properties of multiple surfaces of an aluminum alloy, for example, the impactor can be controlled to compress the aluminum alloy towards the platform, subjecting the alloy to compression by both the platform and the impactor, thus achieving a crushing test on the surface of the aluminum alloy parallel to the platform. Alternatively, the impactor can be controlled to compress the aluminum alloy towards the support plate, subjecting the alloy to compression by both the support plate and the impactor, thus achieving a crushing test on the surface of the aluminum alloy parallel to the support plate.

[0103] In particular, when aluminum alloys are used in automotive profiles, to simulate the crushing force during a car collision, the side of the profile is usually subjected to impact compression. To simulate the compression of the aluminum alloy side, the side of the aluminum alloy can be oriented towards the compression direction of the impacting component.

[0104] Optionally, the end of the impact member facing the aluminum alloy is provided with a first pressure sensor;

[0105] And / or, the portion of the platform used to set the aluminum alloy is provided with a second pressure sensor;

[0106] And / or, the portion of the support plate used to mount the aluminum alloy is provided with a third pressure sensor.

[0107] To facilitate the recording of the extrusion pressure of the impact component, a first pressure sensor is provided at the end of the impact component facing the aluminum alloy. The extrusion pressure can be obtained from the first pressure sensor during the extrusion process.

[0108] Of course, a second pressure sensor can also be installed on the part of the platform where the aluminum alloy is placed. When the impactor extrudes the aluminum alloy in the direction of the platform, the extrusion force can also be obtained from the second pressure sensor.

[0109] A third pressure sensor can also be installed on the support plate where the aluminum alloy is placed. When the impactor extrudes the aluminum alloy in the direction of the support plate, the extrusion pressure can also be obtained from the third pressure sensor.

[0110] Optionally, the displacement distance of the surface of the extruded part of the aluminum alloy before and after extrusion is defined as H1, the extrusion force is defined as F1, the extrusion force-displacement distance data of the test is extracted, the extrusion force and displacement distance curve is obtained on the x and y coordinate axes, the area enclosed between the curve and the x-axis is calculated, and the energy absorption value is obtained.

[0111] Energy absorption performance refers to the ability of aluminum alloys to absorb a large amount of impact energy when wrinkled at the crushed area during a crush test. In essence, energy-absorbing design utilizes structural deformation to dissipate energy. Upon impact, the deformation of the energy-absorbing zone dissipates some of the energy, ensuring that the energy transmitted to the passenger compartment or battery cell area is less than the structure's structural capacity, thus preventing deformation and better guaranteeing passenger or battery cell safety.

[0112] After extrusion, the extruded part of the aluminum alloy will be deformed under stress. In order to calculate the energy absorption performance of the aluminum alloy, the displacement distance of the surface of the extruded part of the aluminum alloy before and after extrusion is H1, and the extrusion force is F1. The extrusion force-displacement distance data of the test is extracted, and the extrusion force and displacement distance curve is obtained on the x and y coordinate axes. The area enclosed between the curve and the x-axis is calculated to obtain the energy absorption value.

[0113] Optionally, the impact head of the impact member is spherical or hemispherical;

[0114] And / or, the loading speed of the impact member ranges from 50 mm / min to 100 mm / min.

[0115] This application does not limit the shape of the impact head of the impact component. However, in order to avoid damage to the aluminum alloy by the impact head with sharp edges during the extrusion process, the shape of the impact head is preferably spherical or hemispherical.

[0116] The aluminum alloy of this application, by mass percentage, comprises: La, 0.08-0.15%; Si, 0.55% to 0.65%; Mg, 0.48% to 0.58%; Fe, 0.15% to 0.25%; Mn, 0.15% to 0.25%; Cr, 0.06% to 0.12%; Ti, 0.05% to 0.10%; with the balance being Al. The addition of an appropriate amount of Si can improve the casting performance and corrosion resistance of the aluminum alloy, and the improved casting performance can improve the quality and performance of the castings. The addition of an appropriate amount of Mg improves the plasticity and crushability of the aluminum alloy; the addition of La within the above range can improve the deoxidation and impurity removal effect, improve the fluidity of the molten aluminum alloy, refine the aluminum alloy grains, make the microstructure uniform, and improve the mechanical properties of the aluminum alloy. Fe and Mn elements increase the recrystallization temperature of aluminum alloys and inhibit recrystallized grain growth. Controlling Fe content within the aforementioned range mitigates the problem of excessive Fe content negatively impacting product surface quality. Similarly, controlling Mn content within the aforementioned range mitigates the problem of excessive Mn content leading to the formation of coarse intermetallic compound primary crystals. Cr element inhibits recrystallization nucleation and growth. Ti element refines the casting microstructure. The addition of these elements improves the strength and plasticity of aluminum alloys, enhancing their overall performance and compressibility. Attached Figure Description

[0117] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0118] Figure 1 This is a schematic diagram of a method for preparing an aluminum alloy according to an embodiment of this application;

[0119] Figure 2 This is a schematic diagram of an aluminum alloy crush test according to an embodiment of this application;

[0120] Figure 3 This is a schematic diagram of an aluminum alloy crush test according to an embodiment of this application;

[0121] Figure 4 This is a curve showing the extrusion force and displacement distance according to an embodiment of this application;

[0122] Figure 5 This is a schematic diagram of the crush test in Embodiment 1 of this application.

[0123] Explanation of icon numbers:

[0124] label name label name 10 Support structure 30 Aluminum alloy profiles 11 platform 31 A surface 13 support plate 32 Another surface 20 Impact components

[0125] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0126] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0127] The following detailed description, with appropriate reference to the accompanying drawings, discloses embodiments of the aluminum alloy and its preparation method, as well as the crush test method for the aluminum alloy. However, unnecessary details may be omitted. For example, detailed descriptions of well-known matters and repetitive descriptions of essentially identical structures may be omitted. This is to avoid unnecessarily lengthy descriptions and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided to enable those skilled in the art to fully understand this application and are not intended to limit the subject matter of the claims.

[0128] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a specific parameter, it is expected that ranges of 60-110 and 80-120 are also included. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this application, unless otherwise stated, the numerical range "ab" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed in this article; "0-5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0129] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.

[0130] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.

[0131] Unless otherwise specified, all steps in this application may be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), indicating that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order. For example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc.

[0132] Aluminum alloys are one of the most widely used metal structural materials in industry.

[0133] During a collision, aluminum alloy structures typically need to be able to resist external impact forces.

[0134] For example, safety collision components need to possess excellent crush resistance. Taking automobiles as an example, in the event of a collision, aluminum alloys can absorb the impact energy to protect the safety of the driver and passengers. For battery-powered new energy vehicles, it is also necessary to prevent external forces from damaging the battery pack and to avoid secondary injuries such as fires caused by battery compression. Therefore, there are very high performance requirements for automotive collision safety components, especially crush resistance.

[0135] To improve the crushing properties of aluminum alloys, this application provides an aluminum alloy comprising, by mass percentage: La, 0.08% to 0.15%; Si, 0.55% to 0.65%; Mg, 0.48% to 0.58%; Fe, 0.15% to 0.25%; Mn, 0.15% to 0.25%; Cr, 0.06% to 0.12%; Ti, 0.05% to 0.10%; with the balance being Al.

[0136] An alloy is a mixture of two or more metals and metals or non-metals synthesized by a certain method, which has metallic properties.

[0137] La is a rare earth element. When the amount of La added is within the above range, it can improve the deoxidation and impurity purification effect, improve the fluidity of aluminum alloy liquid, refine the aluminum alloy grains, make the structure uniform, and improve the mechanical properties of aluminum alloy.

[0138] The addition of appropriate amounts of silicon (Si) can improve the casting performance and corrosion resistance of aluminum alloys. Improved casting performance leads to enhanced casting quality and performance. The addition of appropriate amounts of magnesium (Mg) improves the plasticity and crushability of aluminum alloys. Fe and Mn elements increase the recrystallization temperature of aluminum alloys and inhibit recrystallized grain growth. Controlling Fe content within the aforementioned range mitigates the problem of excessive Fe content negatively impacting product surface quality, while controlling Mn content within the same range mitigates the problem of excessive Mn content leading to the formation of coarse intermetallic compound primary crystals. Cr element inhibits recrystallization nucleation and growth. Ti element refines the casting microstructure. Through the addition of these elements, the strength and plasticity of aluminum alloys are improved, enhancing overall performance and crushability.

[0139] The values ​​in the range of 0.08% to 0.15% include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Specific examples include, but are not limited to, the point values ​​in the embodiments, and 0.08%, 0.09%, 0.10%, 0.11%, 0.12%, 0.13%, 0.14%, 0.15%, etc., as well as the range values ​​between any two of the above point values.

[0140] The values ​​in the range of 0.55% to 0.65% include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Specific examples include, but are not limited to, the point values ​​in the embodiments, and 0.55%, 0.57%, 0.59%, 0.60%, 0.62%, 0.64%, 0.65%, etc., as well as the range values ​​between any two of the above point values.

[0141] The values ​​in the range of 0.48% to 0.58% include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Specific examples include, but are not limited to, the point values ​​in the embodiments, and 0.48%, 0.49%, 0.50%, 0.51%, 0.52%, 0.53%, 0.54%, 0.55%, 0.56%, 0.57%, 0.58, etc., as well as the range values ​​between any two of the above point values.

[0142] The values ​​in the range of 0.15% to 0.25% include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Specific examples include, but are not limited to, the point values ​​in the embodiments, and 0.15%, 0.16%, 0.17%, 0.18%, 0.19%, 0.20%, 0.21%, 0.22%, 0.23%, 0.24%, 0.25, etc., as well as the range values ​​between any two of the above point values.

[0143] The values ​​in the range of 0.06% to 0.12% include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Specific examples include, but are not limited to, the point values ​​in the embodiments, and 0.06%, 0.07%, 0.08%, 0.09%, 0.10%, 0.11%, 0.12%, etc., as well as the range values ​​between any two of the above point values.

[0144] The values ​​in the range of 0.05% to 0.10% include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Specific examples include, but are not limited to, the point values ​​in the embodiments, and 0.05%, 0.06%, 0.07%, 0.08%, 0.09%, 0.10%, etc., as well as the range values ​​between any two of the above point values.

[0145] In one embodiment, the mass percentage of La is 0.1% to 0.15%; and / or, the mass percentage of Si is 0.57% to 0.62%; and / or, the mass percentage of Mg is 0.5% to 0.55%; and / or, the mass percentage of Fe is 0.15% to 0.2%; and / or, the mass percentage of Mn is 0.19% to 0.24%; and / or, the mass percentage of Cr is 0.08% to 0.12%; and / or, the mass percentage of Ti is 0.06% to 0.10%; and / or, the mass percentage of Zn in the aluminum alloy is ≤0.05%; and / or, the mass percentage of Cu in the aluminum alloy is ≤0.05%.

[0146] To further improve the strength and plasticity of aluminum alloys, enhance their overall performance, and improve their crushability, the mass percentages of La are controlled as follows: 0.1% to 0.15%; Si: 0.57% to 0.62%; Mg: 0.5% to 0.55%; Fe: 0.15% to 0.2%; Mn: 0.19% to 0.24%; Cr: 0.08% to 0.12%; Ti: 0.06% to 0.10%; Zn: ≤0.05%; Cu: ≤0.05%. It is understood that higher Zn and Cu mass percentages increase strength, but increased strength reduces the crushability of the aluminum alloy. Furthermore, Zn and Cu are relatively expensive; therefore, their mass percentages are controlled within the aforementioned ranges.

[0147] Ti is added online in the form of Al-Ti wire or Al-Ti-B wire before casting, where B is an impurity element with a content of ≤0.05%, forming TiAl3, which becomes a non-spontaneous nucleus during crystallization and refines the casting structure.

[0148] Understandably, the finer the grains, meaning the more grains per unit volume, the more grain boundaries there are, and the more tortuous the grain boundaries, the greater the resistance to dislocations, and the higher the strength. At the same time, under the same amount of plastic deformation, the deformation is distributed within more grains, resulting in more uniform deformation; fewer dislocations are piled up in each grain, reducing the chance of cracking due to stress concentration, and allowing it to withstand a greater amount of deformation before fracture.

[0149] There is a contradictory relationship between the strength and crushability of aluminum alloys. During their manufacturing process, high strength often corresponds to low folding performance, and high folding performance often corresponds to low strength. By adding appropriate amounts of the aforementioned elements, it is possible to improve both the strength and crushability of aluminum alloys; that is, to improve crushability while meeting structural strength requirements.

[0150] like Figure 1 As shown, this application also provides a method for preparing an aluminum alloy, comprising: preparing the formulation components of the aluminum alloy to obtain raw materials; melting, refining, degassing, removing slag from the raw materials, and casting them to obtain an aluminum alloy casting.

[0151] In the process of preparing aluminum alloys, the various components of the aluminum alloy are prepared to obtain raw materials; the raw materials are melted, refined, degassed, slag removed, and cast to obtain aluminum alloy castings.

[0152] Cast aluminum alloys have a strong hydrogen absorption capacity, resulting in numerous needle-like porosity defects. Furthermore, the casting process itself introduces inclusions, shrinkage cavities, and other defects. These casting defects severely reduce the physical, chemical, and mechanical properties of the cast aluminum alloys. To overcome these defects, after the raw materials are melted, refining, degassing, and slag removal processes are performed to reduce or eliminate casting porosity.

[0153] In one embodiment, after melting, refining, degassing, removing slag, and casting the raw materials to obtain an aluminum alloy casting, the process further includes the following step: homogenizing the aluminum alloy casting under the following conditions: holding temperature 575℃±10℃, holding time 6h to 8h.

[0154] Homogenization treatment, also known as homogenization annealing, is a process in which an alloy ingot is heated to near the unequilibrium solidus temperature and held at that temperature for a relatively long time, and then slowly cooled to room temperature. Its purpose is to eliminate or reduce the inhomogeneity of the intracrystalline chemical composition and structure of the alloy through the diffusion of alloy element atoms, improve the internal structure of the ingot, eliminate residual stress in the ingot, improve the machinability of the ingot, and at the same time improve plasticity, reduce deformation resistance, and improve the hot working properties of the alloy.

[0155] To improve the properties of the alloy, after obtaining the aluminum alloy casting, the alloy casting is also homogenized. Homogenization can improve the internal structure of the alloy, reduce residual stress, improve machinability, increase plasticity, reduce deformation resistance, and improve the processing performance of the alloy.

[0156] To improve the performance of aluminum alloy castings, the homogenization treatment was carried out at a holding temperature of 575℃±10℃ for 6 to 8 hours.

[0157] It is understandable that the diameter of aluminum alloy castings ranges from 90mm to 500mm, and the corresponding holding time is 6h to 8h. The larger the diameter, the longer the holding time, which improves the internal structure of the aluminum alloy rod, eliminates residual stress, and dissolves the primary strengthening phase Mg2Si.

[0158] The values ​​in the range of 6h to 8h include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Specific examples include, but are not limited to, the point values ​​in the embodiments, as well as 6h, 6.5h, 7h, 7.5h, 8h, etc., and the range values ​​between any two of the above point values.

[0159] In one embodiment, after homogenizing the aluminum alloy casting, a cooling step is further included. The cooling conditions are: air cooling to a temperature greater than or equal to 200°C and less than 250°C, followed by water cooling to room temperature. Room temperature refers to the current ambient temperature, which varies depending on the location, season, or workshop. It is not specifically limited; for example, room temperature can range from 10°C to 50°C.

[0160] This application adopts a mist cooling method, which refers to generating atomized water vapor through a mist cooling device and spraying the atomized water vapor onto the aluminum alloy casting that needs to be cooled. This cooling method has a fast cooling speed, which is beneficial to preserving the microstructure of the aluminum alloy casting at high temperature. Rapid cooling can also shorten the processing time.

[0161] The values ​​in the range of 200°C or higher and less than 250°C include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Specific examples include, but are not limited to, the point values ​​in the embodiments, and 200°C, 210°C, 220°C, 230°C, 240°C, 245°C, etc., as well as the range values ​​between any two of the above point values.

[0162] In one embodiment, the steps of melting, refining, degassing, removing slag, and casting the raw materials to obtain aluminum alloy castings include: melting Al in a melting furnace at a melting temperature of 710°C to 750°C, adding Fe, Mn, Cr, Si, and La, and then adding Mg to obtain aluminum liquid A; refining, degassing, and removing slag from the aluminum liquid A; adding aluminum-titanium wire to melt the aluminum liquid B; and casting the aluminum liquid B.

[0163] The steps of melting, refining, degassing, removing slag, and casting the raw materials to obtain aluminum alloy castings include: melting Al in a melting furnace at a melting temperature of 710℃ to 750℃, adding Fe, Mn, Cr, Si, and La, and then adding Mg to obtain aluminum liquid A; refining, degassing, and removing slag from aluminum liquid A; adding aluminum-titanium wire to obtain aluminum liquid B; and casting aluminum liquid B.

[0164] This application employs a step-by-step feeding method for the raw materials into the melting furnace. The order in which the raw materials are fed not only affects the melting efficiency and alloy consumption but also directly impacts the quality of the molten aluminum alloy. By adopting the above-described feeding steps, melting efficiency can be improved and alloy consumption reduced.

[0165] When charging the smelting furnace, small pieces or thin sheets of scrap are charged first, followed by aluminum ingots and larger pieces. Master alloys are charged last, with easily oxidized master alloys placed in the lower layers. The charged material should be evenly distributed in the molten pool to prevent uneven distribution. Placing small pieces or thin sheets in the lower layer reduces burn-off and protects the furnace from direct impact from larger pieces. It is understandable that when adding Fe, Mn, Cr, Si, and La to the smelting furnace, these metals can be added in alloy form, such as Al-Fe, Al-Mn, Al-Cr, Al-Si, and Al-La. The Al-Mn master alloy used in this design has a relatively high melting point (750℃-800℃) and should be placed in the upper layer. The higher temperature in the upper part of the furnace facilitates melting and allows sufficient time for diffusion, resulting in a more uniform distribution of the master alloy and better control of the melt composition.

[0166] The furnace charge is leveled, ensuring a relatively uniform melting rate throughout, which prevents localized overheating caused by uneven weight distribution. This charging method not only reduces burn-off but also increases the melting rate, facilitating composition control. Furthermore, it minimizes temperature fluctuations within the furnace, provides good protection for the furnace bottom, and helps extend the furnace's lifespan.

[0167] The values ​​in the range of 710℃ to 750℃ include the minimum and maximum values ​​of this range, as well as every value between the minimum and maximum values. Specific examples include, but are not limited to, the point values ​​in the embodiments, and 710℃, 720℃, 730℃, 740℃, 750℃, etc., as well as the range values ​​between any two of the above point values.

[0168] In one embodiment, the refining conditions are as follows: refining is carried out using argon gas and a sodium-free refining agent, with the amount of sodium-free refining agent used being 1.8 kg to 2.2 kg per ton of Al; the refining temperature is 730°C to 750°C, and the refining time is 15 min to 20 min; and / or, the degassing conditions are as follows: online degassing is carried out using a dual-rotor degassing box; and / or, the slag removal conditions are as follows: slag removal is carried out using a filter plate.

[0169] In one embodiment, the casting conditions are as follows: the aluminum B liquid is formed and cast using a hot-top casting machine. During the casting process, the temperature of the aluminum B liquid reaching the casting pan is controlled at 700°C to 720°C, and the casting speed of the casting machine is 100 mm / min to 130 mm / min.

[0170] Refining is the process of removing impurities from the molten aluminum. It's understood that increased slag and gas content in the molten aluminum alters its chemical composition, leading to pinholes, oxide inclusions, shrinkage porosity, and substandard chemical composition in the castings, thus affecting casting quality. To obtain qualified aluminum alloy castings, the aforementioned refining conditions are employed. In-furnace refining primarily involves using granular refining agents to adsorb inclusions and float them to the surface of the molten aluminum, making the molten aluminum purer and reducing defects such as porosity, inclusions, and looseness in the aluminum rods.

[0171] It is understood that the sodium-free refining agent in this application is not specifically limited, and may include, but is not limited to, calcium fluoride, potassium fluorosilicate, potassium chloride, lithium chloride, magnesium chloride, calcium oxide, titanium dioxide powder, and carbon powder.

[0172] The degassing conditions are: online degassing using a dual-rotor degassing box.

[0173] During the melting process, aluminum alloys absorb hydrogen gas, for example, through reactions between the molten aluminum alloy and water vapor. Hydrogen absorption leads to pinholes in the aluminum alloy castings, reducing their airtightness and mechanical properties. To improve the performance of aluminum alloy castings, hydrogen is removed through a degassing process. Refining aluminum alloys using argon gas injection, for example, employing online degassing with a dual-rotor degassing box to rotaryly inject argon gas, can remove hydrogen and inclusions, purify the molten aluminum, and eliminate pinholes in the castings.

[0174] Its working principle is that when the motor drives the rotor to rotate (usually at a speed of 380-450 rpm), argon gas (flow rate of 0.5 m³ / min) is released.3 / hour -1.5m 3 The hydrogen is broken into very small bubbles (per hour). The presence of these small bubbles reduces the concentration of hydrogen in the molten aluminum and its surface partial pressure, thereby reducing the concentration of hydrogen in the molten aluminum. This causes the hydrogen to be carried out of the molten aluminum surface by argon gas and burned off on the surface.

[0175] Furthermore, as argon gas bubbles move from the bottom of the molten aluminum to the surface, the hydrogen dissolved in the aluminum changes from a dissolved state to an adsorbed state upon encountering the argon-aluminum interface. Gas atoms in the adsorbed layer react to generate hydrogen molecules, which rise to the surface of the molten aluminum and burn off as the bubbles grow larger. Additionally, as the argon gas bubbles move from the bottom of the molten aluminum to the surface, suspended particles in the aluminum are agitated, colliding, aggregating, and growing. When these inclusions reach a certain size, they may collide with rising bubbles, be captured, and brought to the surface, thus achieving slag removal. This reduces defects such as porosity, slag inclusions, and looseness in aluminum rods.

[0176] The conditions for slag removal are: using a filter plate for slag removal.

[0177] During the melting process, aluminum alloy raw materials absorb gas and oxidize, forming oxide inclusions inside or on the surface of the molten aluminum alloy. These inclusions are easily adsorbed by gases within the molten aluminum alloy, making it difficult for these gases to escape. The presence of both gas and oxide inclusions in the molten aluminum alloy leads to defects such as porosity and inclusions in the aluminum alloy castings. To improve the performance of aluminum alloy castings, slag removal processes are used to remove slag from the molten aluminum alloy. For example, a two-stage filter plate with a mesh size of 40 to 60 mesh can be used.

[0178] The casting conditions are as follows: the aluminum B liquid is formed and cast by a hot-top casting machine. During the casting process, the temperature of the aluminum B liquid reaching the casting pan is controlled at 700℃ to 720℃, and the casting speed of the casting machine is 100mm / min to 130mm / min.

[0179] Melting and casting refers to the process of shaping molten aluminum alloy into a solid alloy of a specific shape under certain conditions. For example, molten aluminum alloy is poured into a mold for casting; the mold is equipped with a water-cooling system to control the cooling rate during casting, and argon gas is used for protection during pouring. The mold is then cooled and solidified to obtain the molten aluminum alloy casting. The aforementioned melting and casting conditions are used to eliminate problems such as uneven microstructure, coarse grains, and compositional segregation in molten aluminum alloy castings.

[0180] The values ​​in the range of 730°C to 750°C include the minimum and maximum values ​​of this range, as well as every value between the minimum and maximum values. Specific examples include, but are not limited to, the point values ​​in the embodiments, as well as 730°C, 740°C, 750°C, etc., and the range values ​​between any two of the above point values.

[0181] The values ​​in the range of 1.8kg to 2.2kg include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Specific examples include, but are not limited to, the point values ​​in the embodiments, as well as 1.8kg, 1.9kg, 2kg, 2.1kg, 2.2kg, etc., and the range values ​​between any two of the above point values.

[0182] The values ​​within the range of 15 min to 20 min include the minimum and maximum values ​​of that range, as well as every value between the minimum and maximum values. Specific examples include, but are not limited to, the point values ​​in the embodiments, and 15 min, 16 min, 17 min, 18 min, 19 min, 20 min, etc., as well as the range values ​​between any two of the above point values.

[0183] The values ​​in the range of 700℃ to 720℃ include the minimum and maximum values ​​of this range, as well as every value between the minimum and maximum values. Specific examples include, but are not limited to, the point values ​​in the embodiments, as well as 700℃, 710℃, 720℃, etc., and the range values ​​between any two of the above point values.

[0184] The values ​​in the range of 100 mm / min to 130 mm / min include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Specific examples include, but are not limited to, the point values ​​in the embodiments, as well as 100 mm / min, 110 mm / min, 120 mm / min, 130 mm / min, etc., and the range values ​​between any two of the above point values.

[0185] In one embodiment, the average grain size range of the as-cast microstructure of the aluminum alloy obtained after melting and casting is ≤150 μm.

[0186] As-cast microstructure refers to the microstructure formed when a metallic (mostly alloy) material transforms from a molten metal into a solid during the smelting process. By applying the aforementioned process conditions, the average grain size of the as-cast aluminum alloy is within the range described above. Fine as-cast grains contribute to improved strength and plasticity of the aluminum alloy, and enhance its crushing performance during impact and extrusion processes.

[0187] Measurement of grain size: Refer to GB / T 3246.1 Inspection methods for microstructure of wrought aluminum and aluminum alloy products - Part 1: Inspection methods for microstructure.

[0188] In one embodiment, after melting, refining, degassing, removing slag, and casting the raw material to obtain an aluminum alloy casting, the process further includes heating, extruding, quenching, and cutting the aluminum alloy casting to obtain an aluminum alloy profile.

[0189] Profiles are objects with a certain geometric shape made of iron or steel and materials with a certain strength and toughness (such as plastics, aluminum, glass fiber, etc.) through processes such as rolling, extrusion, and casting.

[0190] To obtain aluminum alloy profiles with suitable dimensions and performance, the prepared aluminum alloy castings can be heated, extruded, quenched, and cut to obtain aluminum alloy profiles.

[0191] The heating step softens the aluminum alloy casting, facilitating subsequent extrusion deformation. The extrusion step involves hot-extending the heated aluminum alloy casting using an extrusion press to shape it into a specific form. Quenching is a metal heat treatment process that involves heating a metal workpiece to a suitable temperature and holding it for a period of time, followed by rapid cooling in a quenching medium. Quenching can improve the properties of aluminum alloys. Cutting refers to using cutting tools to cut the aluminum alloy into profiles of a specific size.

[0192] In one embodiment, the step of heating, extruding, quenching, and cutting the aluminum alloy casting to obtain an aluminum alloy profile includes: heating, extruding, quenching, stretching and straightening, and cutting the aluminum alloy casting to obtain an aluminum alloy profile.

[0193] Tensile straightening refers to the process of clamping both ends of an aluminum alloy with two clamping devices and generating tensile force to cause plastic deformation of the aluminum alloy, thereby achieving the purpose of tension straightening.

[0194] Stretching and straightening can improve the internal stress of aluminum alloys, thereby improving their strength, resistance to stress corrosion, and structural dimensional stability.

[0195] In one embodiment, the step of heating, extruding, quenching, and cutting the aluminum alloy casting to obtain an aluminum alloy profile includes: heating, extruding, quenching, cutting, and aging the aluminum alloy casting to obtain the aluminum alloy profile.

[0196] Aging is a heat treatment process in which supersaturated solid solution alloys are heated to room temperature or held at a certain temperature to enrich solute components or precipitate a second phase. Aging at room temperature is called natural aging. Aging at temperatures above room temperature is called artificial aging. The phenomenon of strengthening by the precipitation of a second phase during aging is called age strengthening. Aging below or above the peak strengthening temperature is called sub-aging and over-aging treatment, respectively.

[0197] To improve the toughness of aluminum alloys and address their tendency to fracture during extrusion, an aging treatment is performed on the aluminum alloy after cutting. This process eliminates residual stress within the aluminum alloy profile, stabilizes its shape, dimensions, strength, and hardness, and ultimately enhances the overall mechanical properties of the aluminum alloy profile.

[0198] In one embodiment, the heating and extrusion conditions of the aluminum alloy casting are as follows: heating the extrusion die to 470°C to 500°C and holding it at that temperature for 4 hours to 12 hours, and then heating the aluminum alloy casting to 460°C to 500°C and extruding it at an extrusion speed of 1.5 mm / s to 5.0 mm / s.

[0199] In order to soften the aluminum alloy castings to facilitate subsequent extrusion deformation and to achieve a certain solution treatment effect, the heating temperature is 460℃ to 500℃.

[0200] To refine the extruded microstructure grains, the extrusion conditions are as follows: heating the extrusion die to 470°C to 500°C and holding it at that temperature for 4 to 12 hours; heating the aluminum alloy casting to 460°C to 500°C and extruding at an extrusion speed of 1.5 mm / s to 5.0 mm / s.

[0201] Understandably, the quenching temperature at the discharge port is controlled by a combination of heating temperature and extrusion speed. To ensure production efficiency, the extrusion speed is generally increased as much as possible within the limits of the mold. The faster the speed, the higher the frictional heat generated between metals and between metals and the mold (extrusion temperature rise), and the higher the discharge port temperature will be. Excessive temperature can lead to coarse grains in the profile structure and even cracking. Therefore, it is necessary to appropriately reduce the heating temperature of the aluminum alloy casting to balance the quenching temperature at the discharge port. For this purpose, the heating temperature is 460℃ to 500℃.

[0202] The values ​​in the range of 470℃ to 500℃ include the minimum and maximum values ​​of this range, as well as every value between the minimum and maximum values. Specific examples include, but are not limited to, the point values ​​in the embodiments, as well as 470℃, 480℃, 490℃, 500℃, etc., and the range values ​​between any two of the above point values.

[0203] The values ​​in the range of 460°C to 500°C include the minimum and maximum values ​​of this range, as well as every value between the minimum and maximum values. Specific examples include, but are not limited to, the point values ​​in the embodiments, as well as 460°C, 470°C, 480°C, 490°C, 500°C, etc., and the range values ​​between any two of the above point values.

[0204] The values ​​in the range 4h to 12h include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Specific examples include, but are not limited to, the point values ​​in the embodiments, as well as 4h, 5h, 6h, 7h, 8h, 9h, 10h, 11h, 12h, etc., and the range values ​​between any two of the above point values.

[0205] The values ​​in the range of 1.5 mm / s to 5.0 mm / s include the minimum and maximum values ​​of this range, as well as every value between the minimum and maximum values. Specific examples include, but are not limited to, the point values ​​in the embodiments, and 1.5 mm / s, 2 mm / s, 2.5 mm / s, 3 mm / s, 3.5 mm / s, 4 mm / s, 4.5 mm / s, 5.0 mm / s, etc., as well as the range values ​​between any two of the above point values.

[0206] In one embodiment, the average grain size of the extruded microstructure ranges from 80 μm to 120 μm.

[0207] The values ​​in the range of 80μm to 120μm include the minimum and maximum values ​​of this range, as well as every value between the minimum and maximum values. Specific examples include, but are not limited to, the point values ​​in the embodiments, and 80μm, 85μm, 90μm, 95μm, 100μm, 110μm, 115μm, 120μm, etc., as well as the range values ​​between any two of the above point values.

[0208] Through the above steps, the average grain size of the extruded microstructure in this application meets the aforementioned range. Refined extruded microstructure grains help improve the strength and plasticity of the aluminum alloy, and enhance its crushing performance during impact extrusion.

[0209] In one embodiment, the quenching conditions are: a quenching temperature range of 500°C to 535°C, and a cooling intensity ≥8°C / s; and / or, the quenching method includes spray cooling or water cooling.

[0210] To ensure the strength and toughness of the profile, the quenching temperature range is 500℃ to 535℃, and the cooling intensity is ≥8℃ / s.

[0211] The quenching methods include spray cooling or water cooling.

[0212] Spray cooling can be an online quenching method. Online quenching refers to quenching while extruding, while offline quenching is quenching after extrusion. This application does not limit the quenching method, but online quenching is preferred because it can reduce costs and improve efficiency.

[0213] The quenching method can be spray cooling or water cooling. Among them, water cooling is preferred according to the profile structure. Water cooling has high cooling intensity, good cooling effect and short cooling time. This process can inhibit grain growth and help improve the performance of aluminum alloy.

[0214] As is understandable, water cooling refers to the use of a water cooling device for cooling. This device includes a water-cooled box with inlet and outlet water pipes. Cooling water is sprayed out from the inlet pipe, collected in the water-cooled box, and discharged through the drain outlet at the bottom of the box, thus achieving circulation and preventing the water temperature inside the box from becoming too high and affecting the quenching effect.

[0215] The values ​​in the range of 500℃ to 535℃ include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Specific examples include, but are not limited to, the point values ​​in the embodiments, and 500℃, 510℃, 515℃, 520℃, 525℃, 530℃, 535℃, etc., as well as the range values ​​between any two of the above point values.

[0216] In one embodiment, during the stretching and straightening process, the elongation rate of the stretch is 0.5% to 1.3%.

[0217] Stretch straightening can improve the internal stress of aluminum alloys. To improve performance, the elongation rate during stretch straightening is 0.5 to 1.3 times. Elongation rate = (length after stretching - length before stretching) / length before stretching * 100%. Stretch straightening can eliminate longitudinal shape irregularities and reduce residual stress. The elongation rate range is 0.5% to 1.3%. If the elongation rate is too low, it will not have the effect of straightening and eliminating internal stress. If the elongation rate is too high, it will cause a decrease in the plasticity of the profile, orange peel surface, local thinning, or dimensional deviations from tolerance.

[0218] In one embodiment, the aging treatment conditions include over-aging treatment, wherein the over-aging treatment temperature is 205°C to 210°C and the holding time is 4.5h to 6h.

[0219] To improve the toughness of aluminum alloys, aging treatment conditions include over-aging, with over-aging temperatures ranging from 205℃ to 210℃ and holding times ranging from 4.5h to 6h. Under certain temperature conditions, when the aging holding time exceeds the peak aging time or the holding temperature exceeds the peak holding temperature, the precipitated phases inside the material begin to grow, and the spacing increases. Macroscopically, this manifests as a decrease in the material's strength, but an improvement in its ductility and toughness.

[0220] The values ​​in the range of 205℃ to 210℃ include the minimum and maximum values ​​of this range, as well as every value between the minimum and maximum values. Specific examples include, but are not limited to, the point values ​​in the embodiments, as well as 205℃, 206℃, 207℃, 208℃, 209℃, 210℃, etc., and the range values ​​between any two of the above point values.

[0221] The values ​​in 4.5h to 6h include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Specific examples include, but are not limited to, the point values ​​in the embodiments, as well as 4.5h, 5h, 5.5h, 6h, etc., and the range values ​​between any two of the above point values.

[0222] This application also provides a crush test method for aluminum alloy, comprising: fixing the aluminum alloy to a support structure; controlling an impactor to compress along the surface of the aluminum alloy profile, the impactor applying a compressive force to the aluminum alloy in a first direction, the support structure being used to provide a constraint reaction force for the aluminum alloy; the aluminum alloy comprising the aluminum alloy as described above, or the aluminum alloy comprising the aluminum alloy obtained by the aluminum alloy preparation method described above.

[0223] Crushing performance refers to a test that uses an impactor with a certain kinetic energy to impact and crush a material of a certain shape in a certain direction to study the deformation of the material.

[0224] like Figure 2 As shown, to test the crushing performance of aluminum alloy, an aluminum alloy profile 30 is fixed to a support structure 10. An impact member 20 is controlled to compress along the surface of the aluminum alloy profile 30, applying compressive force to the profile in a first direction. The support structure 10 provides constraint reaction force to the aluminum alloy. In this way, the aluminum alloy profile is sandwiched between the support structure 10 and the impact member 20 and subjected to compressive force. After the aluminum alloy profile 20 is subjected to compressive force, its shape can be observed to evaluate its crushing performance.

[0225] In one embodiment, in the step of fixing the aluminum alloy to the support structure, the support structure includes a platform and a support plate erected on the platform, the aluminum alloy is disposed on the platform and abuts against the support plate, and the aluminum alloy is fixed to the platform and / or the support plate.

[0226] In order to effectively fix the aluminum alloy profile, the support structure 10 includes a platform 11 and a support plate 13 erected on the platform 11. The two surfaces of the aluminum alloy profile can abut against the platform 11 and the support plate 13 to improve the stability of the aluminum alloy profile installation. In particular, when the shape of the aluminum alloy profile is irregular and difficult to fix, the installation stability of the aluminum alloy profile is improved by limiting the two surfaces.

[0227] In one embodiment, during the step of controlling the extrusion of the impact member along the surface of the aluminum alloy, the extrusion direction of the impact member is toward the platform or support plate.

[0228] To test the crushing performance of multiple surfaces of aluminum alloy profiles, for example, such as Figure 3As shown, the impact member 20 can be controlled to compress the aluminum alloy profile 30 in the direction of the platform 11, so that the aluminum alloy profile 30 is subjected to compression by the platform 11 and the impact member 20, thereby achieving a crushability test on a surface 31 of the aluminum alloy profile parallel to the platform 11. Of course, as... Figure 2 As shown, the impact member 20 can also be controlled to extrude the aluminum alloy profile in the direction of the support plate 13, so that the aluminum alloy profile 30 is extruded by the support plate 13 and the impact member 20, thereby achieving the crushability test of the aluminum alloy profile parallel to the other surface 32 of the support plate 13.

[0229] In particular, when aluminum alloys are used in automotive profiles, to simulate the crushing force during a car collision, the side of the profile is usually subjected to impact compression. To simulate the compression of the aluminum alloy side, the side of the aluminum alloy can be oriented towards the compression direction of the impacting component.

[0230] In one embodiment, the end of the impact member facing the aluminum alloy is provided with a first pressure sensor and / or the portion of the platform used to set the aluminum alloy is provided with a second pressure sensor; and / or the portion of the support plate used to set the aluminum alloy is provided with a third pressure sensor.

[0231] To facilitate the recording of the extrusion pressure of the impactor, a first pressure sensor is installed at the end of the impactor facing the aluminum alloy. The extrusion pressure can be obtained from the first pressure sensor during the extrusion process. Alternatively, a second pressure sensor can be installed at the part of the platform where the aluminum alloy is placed. The extrusion pressure can also be obtained from the second pressure sensor when the impactor extrudes the aluminum alloy in the direction towards the platform. A third pressure sensor can also be installed at the part of the support plate where the aluminum alloy is placed. The extrusion pressure can also be obtained from the third pressure sensor when the impactor extrudes the aluminum alloy in the direction towards the support plate.

[0232] In one embodiment, the displacement distance of the surface of the extruded part of the aluminum alloy before and after extrusion is defined as H1, and the extrusion force is F1. The extrusion force-displacement distance data of the test is extracted, and the extrusion force-displacement distance curve is obtained on the x and y coordinate axes. The area enclosed between the curve and the x-axis is calculated to obtain the energy absorption value.

[0233] Energy absorption performance refers to the ability of aluminum alloys to absorb a large amount of impact energy when wrinkled at the crushed area during a crush test. In essence, energy-absorbing design utilizes structural deformation to dissipate energy. Upon impact, the deformation of the energy-absorbing zone dissipates some of the energy, ensuring that the energy transmitted to the passenger compartment or battery cell area is less than the structure's structural capacity, thus preventing deformation and better guaranteeing passenger or battery cell safety.

[0234] After extrusion, the extruded part of the aluminum alloy undergoes deformation under stress. To calculate the energy absorption performance of the aluminum alloy, the displacement distance H1 of the surface of the extruded part before and after extrusion is obtained, and the extrusion force F1 is taken. The tested extrusion force and displacement distance data are extracted, and the extrusion force-displacement distance curve is obtained on the x and y coordinate axes. The area enclosed by the curve and the x-axis is calculated to obtain the energy absorption value. Figure 4 As shown, this is a pressure-displacement distance curve in one embodiment. The area enclosed between this curve and the x-axis is the energy absorption value.

[0235] In one embodiment, the impact head of the impact member is spherical or hemispherical; and / or, the loading speed of the impact member ranges from 50 mm / min to 100 mm / min.

[0236] This application does not limit the shape of the impact head of the impact component. However, in order to avoid damage to the aluminum alloy by the impact head with sharp edges during the extrusion process, the shape of the impact head is preferably spherical or hemispherical.

[0237] The loading speed range of the impact component in this application is 50 mm / min to 100 mm / min.

[0238] The values ​​in the range of 50 mm / min to 100 mm / min include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Specific examples include, but are not limited to, the point values ​​in the embodiments, and 50 mm / min, 60 mm / min, 70 mm / min, 80 mm / min, 90 mm / min, 100 mm / min, etc., as well as the range values ​​between any two of the above point values.

[0239] Example

[0240] Example 1

[0241] Raw material preparation: Prepare Al, Mg, Al-Si master alloy, La, Fe, Cr, Ti, and Mn according to the alloy composition. The final alloy should meet the following requirements: La: 0.12%, Si: 0.6%, Mg: 0.5%, Fe: 0.2%, Mn: 0.2%, Cr: 0.1%, Ti: 0.07%, with the remainder being Al. Unavoidable impurities should have an individual content of <0.05% and a total content of <0.15%.

[0242] The manufacturing process steps of aluminum alloy:

[0243] At a melting temperature of 725°C, Al is melted in a melting furnace, and Fe, Mn, Cr, Si, and La are added and melted, and Mg is added and melted to obtain aluminum liquid A; aluminum liquid A is refined, degassed, and slag removed; aluminum-titanium wire is added and melted to obtain aluminum liquid B; aluminum liquid B is then cast.

[0244] Argon gas and sodium-free refining agent are used for refining. The amount of sodium-free refining agent used is 2.0 kg per ton of A1 (40 parts potassium chloride, 30 parts potassium fluoroaluminate, 15 parts potassium fluorotitanate, 10 parts potassium fluoroborate, 10 parts potassium carbonate, and 5 parts aluminum fluoride). The refining temperature is 740℃ and the refining time is 20 min.

[0245] Online degassing is achieved using a dual-rotor degassing box with a rotor speed of 400 rpm and an argon flow rate of 1 m³ / min. 3 / hour. A 50-mesh filter plate is used for slag removal. The B-type aluminum liquid is formed and cast using a hot-top casting machine. During the casting process, the temperature of the B-type aluminum liquid reaching the casting pan is controlled at 710℃, and the casting speed of the casting machine is 115mm / min.

[0246] The aluminum alloy castings obtained after melting and casting are subjected to homogenization treatment. The conditions for homogenization treatment are: holding temperature 575℃±10℃, holding time 7h, followed by air cooling to 220℃ and water cooling to 25℃.

[0247] The homogenized aluminum alloy casting is heated to a temperature of 480℃.

[0248] Then, extrusion is performed. The extrusion steps are as follows: heat the extrusion die to 480°C and keep it at that temperature for 8 hours. Then, heat the aluminum alloy casting to 480°C and extrude it at an extrusion speed of 3 mm / s.

[0249] Then, quenching is performed. The quenching steps are as follows: spray cooling is used, the quenching temperature range is 510℃, and the cooling intensity is 8℃ / s.

[0250] Then, stretch straightening is performed, with the elongation rate of the stretch straightening being 1.0%.

[0251] Then cut it.

[0252] Then, an aging treatment is performed. The aging treatment steps are as follows: the aging temperature is 205℃ and the holding time is 4 hours.

[0253] Examples 2 to 3

[0254] Based on Example 1, the raw material formula was adjusted according to Table 1 to obtain the corresponding Examples 2 to 3.

[0255] Example 4

[0256] Based on Example 1, no over-aging process is performed.

[0257] Example 5

[0258] Based on Example 1, no stretching or straightening is performed.

[0259] Example 6

[0260] Based on Example 1, no homogenization process was performed, and the mixture was allowed to cool naturally.

[0261] Comparative Examples 1 to 3

[0262] Comparative Examples 1 to 3 were obtained by adjusting the raw materials based on Example 1.

[0263] Performance testing

[0264] Energy absorption performance:

[0265] like Figure 5 As shown, the prepared aluminum alloy profile was fixed to the support structure, and the impactor was controlled to extrude along the side of the aluminum alloy profile. The loading speed of the impactor (indenter) was 100 mm / min. The displacement distance of the extruded part of the aluminum alloy profile before and after extrusion was measured as H1, and the extrusion force was F1. The force and displacement data were extracted. In this test, the fixed displacement distance was set to 35 mm. The extrusion force-displacement distance curve was obtained on the x and y coordinate axes. The area enclosed between the curve and the x-axis was calculated to obtain the energy absorption value. The extrusion force was measured using a strain gauge force sensor, and the sensor error did not exceed 2% within the range. The deformation results and force-displacement data were observed and recorded, and the surface condition of the wrinkled position of the crushed sample was also observed and recorded.

[0266] Table 1. List of Experimental Data

[0267]

[0268]

[0269] As can be seen from the table above, the energy absorption performance of the aluminum alloy prepared by the aluminum alloy formulation of this application is improved.

[0270] The above are merely preferred embodiments of the present invention and do not limit the scope of the patent. Any equivalent structural transformations made using the contents of the specification and drawings of the present invention under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the scope of patent protection of the present invention.

Claims

1. An aluminum alloy, characterized in that, By mass percentage, including: La, 0.08% to 0.15%; Si, 0.55% to 0.65%; Mg, 0.48% to 0.58%; Fe, 0.15% to 0.25%; Mn, 0.15% to 0.25%; Cr, 0.06% to 0.12%; Ti, 0.05% to 0.10%; The balance is Al; The method for preparing the aluminum alloy includes: Prepare the formulation components of the aluminum alloy to obtain the raw materials; The raw materials are melted, refined, degassed, slag removed, and cast to obtain aluminum alloy castings; The aluminum alloy casting is homogenized under the following conditions: holding temperature 575℃±10℃, holding time 6h to 8h. After homogenizing the aluminum alloy casting, a cooling step is also included. The cooling conditions are: air cooling to a temperature greater than or equal to 200°C and less than 250°C, followed by water cooling to room temperature.

2. The aluminum alloy as described in claim 1, characterized in that, The mass percentage of La is 0.1% to 0.15%; And / or, the mass percentage of Si is 0.57% to 0.62%; And / or, the mass percentage of Mg is 0.5% to 0.55%; And / or, the mass percentage of Fe is 0.15% to 0.2%; And / or, the mass percentage of Mn is 0.19% to 0.24%; And / or, the mass percentage of Cr is 0.08% to 0.12%; And / or, the mass percentage of Ti is 0.06% to 0.10%; And / or, the mass percentage of Zn in the aluminum alloy is ≤0.05%; And / or, the mass percentage of Cu in the aluminum alloy is ≤0.05%.

3. The method for preparing the aluminum alloy as described in claim 1 or 2, characterized in that, include: Prepare the formulation components of the aluminum alloy to obtain the raw materials; The raw materials are melted, refined, degassed, slag removed, and cast to obtain aluminum alloy castings; The aluminum alloy casting is homogenized under the following conditions: holding temperature 575℃±10℃, holding time 6h to 8h. After homogenizing the aluminum alloy casting, a cooling step is also included. The cooling conditions are: air cooling to a temperature greater than or equal to 200°C and less than 250°C, followed by water cooling to room temperature.

4. The method for preparing the aluminum alloy as described in claim 3, characterized in that, The steps of melting, refining, degassing, removing slag, and casting the raw materials to obtain aluminum alloy castings include: At a melting temperature of 710°C to 750°C, Al is melted in a melting furnace, and Fe, Mn, Cr, Si, and La are added and melted, and Mg is added and melted to obtain aluminum liquid A; The aluminum liquid A is refined, degassed, and slag removed. Aluminum-titanium wire is added and melted to obtain molten aluminum (B); The aluminum liquid B is melted and cast.

5. The method for preparing the aluminum alloy as described in claim 3 or 4, characterized in that, The refining conditions are as follows: refining is carried out using argon gas and sodium-free refining agent, with the amount of sodium-free refining agent used being 1.8 kg to 2.2 kg per ton of Al; the refining temperature is 730°C to 750°C, and the refining time is 15 min to 20 min. And / or, the degassing condition is: online degassing using a dual-rotor degassing box; And / or, the slag removal condition is: slag removal is performed by using a filter plate.

6. The method for preparing the aluminum alloy as described in claim 4, characterized in that, The casting conditions are as follows: the aluminum B liquid is formed and cast using a hot-top casting machine. During the casting process, the temperature of the aluminum B liquid reaching the casting pan is controlled at 700℃ to 720℃, and the casting speed of the casting machine is 100mm / min to 130mm / min.

7. The method for preparing the aluminum alloy according to any one of claims 3 to 6, characterized in that, The average grain size range of the as-cast microstructure of the aluminum alloy obtained after melting and casting is ≤150um.

8. The method for preparing the aluminum alloy according to any one of claims 3 to 7, characterized in that, After melting, refining, degassing, removing slag, and casting the raw materials to obtain aluminum alloy castings, the process further includes: The aluminum alloy casting is heated, extruded, quenched, and cut to obtain an aluminum alloy profile.

9. The method for preparing the aluminum alloy as described in claim 8, characterized in that, The steps of heating, extruding, quenching, and cutting the aluminum alloy casting to obtain the aluminum alloy profile include: Aluminum alloy castings are heated, extruded, quenched, stretched, straightened, and cut to obtain aluminum alloy profiles.

10. The method for preparing the aluminum alloy as described in claim 8 or 9, characterized in that, The steps of heating, extruding, quenching, and cutting aluminum alloy castings to obtain aluminum alloy profiles include: The aluminum alloy casting is cut and then subjected to aging treatment to obtain aluminum alloy profiles.

11. The method for preparing the aluminum alloy according to any one of claims 8 to 10, characterized in that, The conditions for heating and extruding the aluminum alloy casting are as follows: heating the extrusion die to 470°C to 500°C and holding it at that temperature for 4 to 12 hours, and then heating the aluminum alloy casting to 460°C to 500°C and extruding it at an extrusion speed of 1.5 mm / s to 5.0 mm / s.

12. The method for preparing the aluminum alloy according to any one of claims 8 to 11, characterized in that, The average grain size of the extruded microstructure ranges from 80 μm to 120 μm.

13. The method for preparing the aluminum alloy according to any one of claims 8 to 12, characterized in that, The quenching conditions are: quenching temperature range of 500℃ to 535℃, and cooling intensity ≥8℃ / s; And / or, the quenching method includes spray cooling or water cooling.

14. The method for preparing the aluminum alloy as described in claim 9, characterized in that, During the stretching and straightening process, the elongation rate is 0.5% to 1.3%.

15. The method for preparing the aluminum alloy as described in claim 10, characterized in that, The aging treatment conditions include over-aging treatment, wherein the over-aging treatment temperature is 205°C to 210°C and the holding time is 4.5h to 6h.

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