Aluminum alloy, preparation method thereof and crushing test method of aluminum alloy

Abstract

The invention relates to the technical field of alloys, in particular to an aluminum alloy, a preparation method thereof and a crushing test method of the aluminum alloy. The aluminum alloy comprises the following components in percentage by mass: 0.08%-0.15% of La, 0.05%-0.15% of Al, and the balance of Al 0.55% to 0.65% of Si; 0.48% to 0.58% of Mg; from 0.15% to 0.25% of Fe; mn, 0.15% to 0.25%; cr, from 0.06% to 0.12%; ti, 0.05% to 0.10%; and the balance of Al. By adding the elements, the strength and plasticity of the aluminum alloy are improved, the comprehensive performance is improved, and the crushing performance of the aluminum alloy is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of alloys, and in particular to an aluminum alloy and a preparation method thereof, and a crushing test method of the aluminum alloy. Background Art

[0002] Aluminum alloy is the most widely used type of metal structural material in industry.

[0003] During a collision of an aluminum alloy structure, it is usually required to have the function of resisting external impact. Summary of the invention

[0004] The main purpose of the present invention is to provide an aluminum alloy, aiming to improve the anti-crushing performance of the aluminum alloy.

[0005] To achieve the above object, the present invention provides an aluminum alloy, which comprises, by mass 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 balance is Al.

[0014] The addition amount of La element in the above range can enhance the effect of deoxidation and purification of impurities, 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 amount of Si can improve the casting performance and corrosion resistance of aluminum alloy. The improved casting performance can improve the quality and performance of castings. The addition of appropriate amount of Mg can improve the plasticity of aluminum alloy and improve the crushing performance of aluminum alloy; Fe and Mn elements increase the recrystallization temperature of aluminum alloy and hinder the growth of recrystallized grains. Among them, the Fe element is controlled within the above range to improve the problem that the high mass content of Fe element is easy to affect the surface quality of the product; the Mn element is controlled within the above range to improve the problem that the high mass content of Mn element is easy to generate coarse primary crystals of intermetallic compounds; Cr element hinders the nucleation and growth of recrystallization; Ti element refines the casting structure; through the addition of the above elements, the strength and plasticity of aluminum alloy are improved, the comprehensive performance is improved, and its crushing performance is improved.

[0016] It is understandable that the finer the grains, that is, the more grains per unit volume, the more grain boundaries, the more tortuous the grain boundaries, the greater the barrier to dislocations, and the higher the strength. At the same time, under the same amount of plastic deformation, the deformation is dispersed in more grains, and the deformation is more uniform; there are fewer dislocations accumulated in each grain, and the chance of cracking due to stress concentration is less, and it can withstand a greater amount of deformation before breaking.

[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] In order to further improve the strength and plasticity of aluminum alloys, improve their comprehensive properties and improve their crushing properties, the mass percentage of La is controlled to be 0.1% to 0.15%; the mass percentage of Si is 0.57% to 0.62%; the mass percentage of Mg is 0.5% to 0.55%; the mass percentage of Fe is 0.15% to 0.2%; the mass percentage of Mn is 0.19% to 0.24%; the mass percentage of Cr is 0.08% to 0.12%; the mass percentage of Ti is 0.06% to 0.10%; the mass percentage of Zn in aluminum alloy is ≤0.05%; the mass percentage of Cu in aluminum alloy is ≤0.05%. It can be understood that the increase in the mass percentage of Zn and Cu will increase the strength, and the increase in strength will reduce the crushing properties of the aluminum alloy. At the same time, Zn and Cu are relatively expensive, so the mass percentages of Zn and Cu are controlled within the above range.

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

[0028] Preparing a formula component of an aluminum alloy to obtain a raw material;

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

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

[0031] Optionally, after the raw materials are melted, refined, degassed, deslagged, and cast to obtain an aluminum alloy casting, the following steps are further included:

[0032] The aluminum alloy casting is homogenized, and the homogenization conditions are: a holding temperature of 575°C±10°C and a holding time of 6h to 8h.

[0033] Homogenization treatment, also known as homogenization annealing, is a process in which the alloy ingot is heated to a temperature close to the unbalanced solidus temperature for a long time and then slowly cooled to room temperature. Its purpose is to eliminate or reduce the heterogeneity of the chemical composition and organization of the alloy through the diffusion of alloy element atoms, improve the internal organization of the ingot, eliminate the residual stress of the ingot, improve the mechanical processing performance of the ingot, and at the same time improve the plasticity, reduce the deformation resistance, and improve the thermal processing performance of the alloy.

[0034] In order to improve the performance of the alloy, after obtaining the aluminum alloy molten casting, the alloy molten casting is also homogenized. The homogenization treatment can improve the internal structure of the alloy, improve the residual stress, improve the mechanical processing performance, increase the plasticity, reduce the deformation resistance, and improve the processing performance of the alloy.

[0035] In order to improve the performance of aluminum alloy castings, the holding temperature of the homogenization treatment is 575℃±10℃, and the holding time is 6h to 8h.

[0036] It can be understood that the diameter of the aluminum alloy casting ranges from 90mm to 500mm, and the corresponding insulation time is 6h to 8h. The larger the diameter, the longer the insulation 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, and the cooling conditions are: wind and mist cooling to a temperature greater than or equal to 200° C. and less than 250° C., and then water cooling to room temperature.

[0038] Room temperature refers to the temperature of the current environment, which varies in each place, season, or workshop, and is not specifically limited. For example, the room temperature may be 10°C to 50°C.

[0039] The present application adopts a wind and mist cooling method. Wind and mist cooling refers to generating atomized water vapor through a wind and 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 retaining the structure of the aluminum alloy casting in a high temperature state. Rapid cooling can also shorten the processing time.

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

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

[0042] The A aluminum liquid is subjected to refining, degassing and deslagging treatments;

[0043] Aluminum titanium wire is added to melt to obtain aluminum liquid B;

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

[0045] The steps of melting, refining, degassing, deslagging and casting the raw materials to obtain aluminum alloy castings include: melting Al in a smelting furnace at a melting temperature of 710°C to 750°C, adding Fe, Mn, Cr, Si, La, and melting them, and adding Mg to melt them to obtain molten aluminum A; refining, degassing and deslagging the molten aluminum A; adding aluminum-titanium wire to melt it to obtain molten aluminum B; and casting the molten aluminum B.

[0046] In this application, the raw materials are fed into the smelting furnace in steps, and the order of feeding the raw materials not only affects the melting efficiency and alloy consumption, but also directly affects the quality of the aluminum alloy liquid. The above-mentioned feeding steps can improve the melting efficiency and reduce the alloy consumption.

[0047] It is understandable that when charging the smelting furnace, small pieces or thin sheets of waste materials are loaded first, aluminum ingots and large pieces are loaded in the middle, and the intermediate alloy is loaded last. The easily oxidized intermediate alloy is loaded in the middle and lower layers. The loaded furnace materials should be evenly distributed in the molten pool to prevent overweight. Small pieces or thin sheets of materials are loaded in the lower layer of the molten pool to reduce burnout and protect the furnace body from direct impact and damage of large pieces of materials. The Al-Mn intermediate alloy added in this scheme has a relatively high melting point (750℃-800℃) and should be loaded in the upper layer. The temperature in the upper part of the furnace is high and easy to melt, and there is also time to fully diffuse, so that the intermediate alloy is evenly distributed, which is conducive to the composition control of the solution.

[0048] The charge is leveled, and the melting speeds of different places are similar, which can prevent local metal overheating caused by heavy loads. The above charging method not only reduces the burning loss, but also increases the melting speed, which is beneficial to the composition control. At the same time, the temperature fluctuation in the furnace is not large, which has a good protection effect on the furnace bottom and is beneficial to increase the furnace life.

[0049] Optionally, the refining conditions are: using argon and a sodium-free refining agent for refining, the amount of the sodium-free refining agent used is 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 conditions are: online degassing using a dual-rotor degassing box;

[0051] And / or, the condition for removing slag is: filtering and removing slag by using a filter plate.

[0052] Optionally, the conditions for the melting and casting are: the B aluminum liquid is molded and cast by a hot top casting machine. During the casting process, the temperature of the B aluminum liquid reaching the casting plate is controlled at 700°C to 720°C, and the casting speed of the casting machine is 100mm / min to 130mm / min.

[0053] Refining is the process of removing impurities from the melt. It is understandable that the slag and gas content of the Al liquid increases, and the chemical composition changes, resulting in pinholes, oxidation slag, shrinkage and unqualified chemical composition in the casting, affecting the quality of the casting. In order to obtain qualified aluminum alloy castings, the above refining conditions are adopted. Furnace refining is mainly achieved by using granular refining agents to absorb slag inclusions and float them to the surface of the aluminum solution, making the aluminum liquid purer and reducing defects such as pores, slag inclusions, and looseness in the aluminum rod.

[0054] It is understandable that the sodium-free refining agent in the present application is not specifically limited, and includes, for example, 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 double-rotor degassing box.

[0056] Aluminum alloys absorb hydrogen during the melting process. For example, the source of hydrogen includes the reaction between aluminum alloy liquid and water vapor. Hydrogen absorption causes pinholes in aluminum alloy castings, reduces air tightness and mechanical properties. In order to improve the performance of aluminum alloy castings, hydrogen is removed through a degassing step. Refining aluminum alloys by blowing argon, for example, using online degassing, using a double-rotor degassing box to rotate and blow argon to refine aluminum alloys, can remove hydrogen and slag inclusions, purify aluminum liquid, and achieve the purpose of eliminating pinholes in castings.

[0057] Its working principle is that when the motor drives the rotor to rotate (usually the speed is 380 rpm-450 rpm), argon gas (flow rate is 0.5m 3 / hour -1.5m 3 / hour) is beaten into very small bubbles. The existence of these small bubbles reduces the concentration of hydrogen in the aluminum liquid and the partial pressure on its surface, thereby reducing the concentration of hydrogen in the aluminum liquid, so that the hydrogen is brought to the surface of the aluminum liquid by argon and burned and consumed on the liquid surface.

[0058] When the small argon bubbles move from the bottom of the aluminum liquid to the surface, the hydrogen dissolved in the aluminum liquid changes from a dissolved state to an adsorbed state when it hits the argon-aluminum liquid interface. The gas atoms in the adsorption layer react to generate hydrogen molecules, which rise to the surface of the aluminum liquid and burn as the bubbles grow. In addition, when the small argon bubbles move from the bottom of the aluminum liquid to the surface, the suspended inclusion particles in the aluminum liquid are stirred, and the inclusions collide, aggregate and grow. When the inclusions reach a certain size, they may collide with the floating bubbles, be captured, and then be brought to the liquid surface to achieve the effect of slag removal. Reduce defects such as pores, slag inclusions, and looseness in aluminum bars.

[0059] The conditions for removing slag are: using a filter plate to filter and remove slag.

[0060] Aluminum alloy raw materials will absorb gas and oxidize during the melting process, forming oxidized slag inside or on the surface of the aluminum alloy liquid. The oxidized slag is easily adsorbed by the gas in the aluminum alloy liquid, making it difficult for the gas to precipitate from the aluminum alloy liquid. The presence of gas and oxidized slag in the aluminum alloy liquid leads to defects such as pores and slag inclusions in the aluminum alloy castings. In order to improve the performance of aluminum alloy castings, the slag in the aluminum alloy liquid is removed through a slag removal process. For example, a 40-60 mesh double-stage filter plate can be used for filtration.

[0061] The casting conditions are as follows: the B aluminum liquid is molded and cast through a hot top casting machine. During the casting process, the temperature of the B aluminum liquid reaching the casting plate is controlled at 700°C to 720°C, and the casting speed of the casting machine is 100mm / min to 130mm / min.

[0062] Melting and casting refers to making aluminum alloy liquid into a solid alloy of a certain shape under certain conditions. For example, the aluminum alloy liquid is poured into a mold for casting; the mold is equipped with a water cooling system, the cooling speed can be controlled during the casting process, argon gas protection is used during the casting process, and the mold after casting is cooled and formed to obtain an aluminum alloy casting. In order to eliminate the problems of uneven structure, coarse grains, and component segregation of aluminum alloy castings, the above-mentioned melting and casting conditions are adopted.

[0063] Optionally, the average grain size range of the cast structure grains of the aluminum alloy obtained after the melting and casting is ≤150um.

[0064] As-cast structure refers to the microstructure formed when the metal (mostly alloy) material is transformed from a molten metal to a solid during the smelting process. Through the above process conditions, the average grain size range of the as-cast structure grains of the aluminum alloy obtained after melting and casting is within the above range. The as-cast structure grains are fine, which helps to improve the strength and plasticity of the aluminum alloy and improve the crushing performance of the aluminum alloy during impact extrusion.

[0065] Optionally, after the raw materials are melted, refined, degassed, deslagged, and cast to obtain an aluminum alloy casting, the process further includes:

[0066] The aluminum alloy molten 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 plastic, aluminum, fiberglass, etc.) through rolling, extrusion, casting and other processes.

[0068] In order to obtain aluminum alloy profiles with suitable size and performance, the prepared aluminum alloy molten casting can be heated, extruded, quenched and cut to obtain aluminum alloy profiles.

[0069] The heating step is to soften the aluminum alloy casting to facilitate subsequent extrusion deformation. The extrusion step is to hot extrude the heated aluminum alloy casting through an extruder to form it into a certain shape. Quenching refers to a metal heat treatment process in which a metal workpiece is heated to a certain temperature and maintained for a period of time, and then immersed in a quenching medium for rapid cooling. Quenching can improve the performance of aluminum alloys. Cutting refers to using cutting tools to cut aluminum alloys into aluminum alloy profiles of a certain size.

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

[0071] The aluminum alloy casting is heated, extruded, quenched, stretched, straightened and cut to obtain aluminum alloy profiles.

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

[0073] After stretching and straightening treatment, the internal stress of aluminum alloy can be improved, thereby improving the strength, stress corrosion resistance and structural dimensional stability of aluminum alloy.

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

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

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

[0077] In order to improve the toughness of aluminum alloy and improve the problem of easy rupture and failure of aluminum alloy during extrusion, the aluminum alloy is subjected to aging treatment after cutting. That is, in order to eliminate the residual stress generated inside the aluminum alloy profile, stabilize its shape, size, strength and hardness, and stably improve the final mechanical properties of the aluminum alloy profile.

[0078] Optionally, the conditions for heating and extruding the aluminum alloy casting are: heating the extrusion die to 470°C to 500°C, keeping it warm for 4h to 12h, heating the aluminum alloy casting to 460°C to 500°C and extruding it at an extrusion speed of 1.5mm / s to 5.0mm / s.

[0079] In order to soften the aluminum alloy casting to facilitate subsequent extrusion deformation and to achieve a certain solid solution effect, the aluminum alloy casting is heated to a temperature of 460°C to 500°C.

[0080] In order to refine the grain size of the extruded structure, the extrusion conditions are as follows: heating the extrusion die to 470°C to 500°C, keeping it warm for 4h to 12h, and heating the aluminum alloy casting to 460°C to 500°C and extruding it at an extrusion speed of 1.5mm / s to 5.0mm / s.

[0081] Optionally, the quenching conditions are: the quenching temperature range is 500° C. to 535° C., and the cooling intensity is ≥ 8° C. / s;

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

[0083] In order 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 method includes spray cooling or water cooling.

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

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

[0087] It is understandable that the heating temperature and extrusion speed comprehensively control the quenching temperature of the discharge port. In order to ensure production efficiency, the extrusion speed is generally accelerated as much as possible under the premise that the extrusion die allows. The faster the speed, the higher the friction heat between metal and metal, metal and die (extrusion temperature rise), the higher the discharge port temperature will be. Too high a temperature will cause the profile structure to be coarse grains or even cracks. Therefore, it is necessary to appropriately reduce the heating temperature of the aluminum alloy casting to balance the quenching temperature of the discharge port. For this purpose, the heating temperature is 460℃ to 500℃.

[0088] Optionally, the average grain size of the grains in the extruded structure after extrusion ranges from 80 μm to 120 μm.

[0089] Through the above steps, the average grain size of the extruded grains of the present invention after extrusion meets the above range. The refined extruded grains help to improve the strength and plasticity of the aluminum alloy and improve the crushing performance of the aluminum alloy during impact extrusion.

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

[0091] Stretching and straightening can improve the internal stress of aluminum alloy. In order to improve the performance, the elongation of stretching and straightening is 0.5 to 1.3 times. Elongation = (length after stretching - length before stretching) / length before stretching * 100%. Stretching and straightening can eliminate the irregular shape in the longitudinal direction and reduce its residual stress. The elongation range is 0.5% to 1.3%. If the elongation is too low, it will not have the effect of straightening and eliminating internal stress. If the elongation is too high, it will cause the plasticity of the profile to decrease, the surface will be orange peel, local thinning or the size will exceed the tolerance range.

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

[0093] In order to improve the toughness of aluminum alloy, the aging treatment conditions include over-aging treatment, the over-aging treatment temperature is 205℃ to 210℃, and the holding time is 4.5h to 6h. Under certain temperature conditions, the aging holding time exceeds the peak aging time, or the holding temperature exceeds the peak holding temperature, the precipitated phase inside the material begins to grow, the spacing becomes larger, and the macroscopic performance is that the strength of the material is reduced and the plastic toughness is improved.

[0094] The present application also provides a crush test method for aluminum alloy, comprising:

[0095] Fixing the aluminum alloy to the supporting structure;

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

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

[0098] In order to test the crushing performance of aluminum alloy, the aluminum alloy is fixed on the support structure, and the impact piece is controlled to be extruded along the surface of the aluminum alloy profile. The impact piece applies extrusion force to the aluminum alloy along the first direction, and the support structure is used to provide a restraining reaction force for the aluminum alloy. In this way, the aluminum alloy can be sandwiched between the support structure and the impact piece and subjected to the extrusion force. After the aluminum alloy is subjected to the extrusion force, the shape of the aluminum alloy can be observed to judge the crushing performance of the aluminum alloy.

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

[0100] In order to effectively fix the aluminum alloy, the supporting structure includes a platform and a supporting plate erected on the platform. The two surfaces of the aluminum alloy can be against the platform and the supporting plate to improve the stability of the installation of the aluminum alloy. Especially when the shape of the aluminum alloy is irregular and difficult to fix, the installation stability of the aluminum alloy is improved by limiting the two surfaces.

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

[0102] In order to test the crushing performance of multiple surfaces of the aluminum alloy, for example, the impact piece can be controlled to extrude the aluminum alloy in the direction where the platform is located, so that the aluminum alloy is squeezed by the platform and the impact piece, and the crushing test of the aluminum alloy surface parallel to the platform is realized. Of course, the impact piece can also be controlled to extrude the aluminum alloy in the direction where the support plate is located, so that the aluminum alloy is squeezed by the support plate and the impact piece, and the crushing test of the aluminum alloy surface parallel to the support plate is realized.

[0103] In particular, when aluminum alloy is used in automobile profiles, the crushability during a car collision is simulated. Generally, the side of the profile is squeezed by the collision. In order to simulate the extrusion of the side of the aluminum alloy, the side of the aluminum alloy can be facing the extrusion direction of the impact part.

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

[0105] And / or, a second pressure sensor is provided at a position of the platform where the aluminum alloy is provided;

[0106] And / or, a third pressure sensor is provided at a portion of the support plate where the aluminum alloy is provided.

[0107] In order to conveniently record the extrusion pressure of the impact piece, a first pressure sensor is provided at the end of the impact piece facing the aluminum alloy, and the extrusion pressure can be obtained from the first pressure sensor during the extrusion process.

[0108] Of course, a second pressure sensor may also be provided at the position of the platform where the aluminum alloy is provided, and when the impact member extrude the aluminum alloy toward the direction where the platform is located, the extrusion force may also be obtained from the second pressure sensor.

[0109] A third pressure sensor may also be provided at a portion of the support plate where the aluminum alloy is provided, and when the impact member extrude the aluminum alloy toward the direction where the support plate is located, the extrusion force may 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 pressure is defined as F1, the extrusion pressure-displacement distance data of the test is extracted, the extrusion pressure and displacement distance curves are 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 fact that in the crush test of aluminum alloy, wrinkles are produced at the extruded part, which can absorb a large amount of impact energy. In fact, the design of energy absorption is to consume energy by using the deformation of the structure. When a collision occurs, the deformation of the energy absorption area consumes part of the energy, ensuring that the energy transmitted to the driving area or the battery area is less than the bearing capacity of the structure without deformation, so as to better ensure the safety of passengers or batteries.

[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 obtained as H1, and the extrusion force is F1. The extrusion force-displacement distance data of the test is extracted, and the extrusion pressure and displacement distance curves are 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 piece is spherical or hemispherical;

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

[0115] The present application does not limit the shape of the impact head of the impact piece. In order to prevent the angular impact head from damaging the aluminum alloy during the extrusion process, the impact head is preferably spherical or hemispherical.

[0116] The aluminum alloy of the present application includes, by mass percentage: 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%; the balance is 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 casting. The addition of an appropriate amount of Mg improves the plasticity of the aluminum alloy and improves the crushing performance of the aluminum alloy; the addition of the La element within the above range can improve the effect of deoxidation and purification of impurities, improve the fluidity of the aluminum alloy liquid, refine the aluminum alloy grains, make the structure uniform, and improve the mechanical properties of the aluminum alloy. Fe and Mn elements increase the recrystallization temperature of aluminum alloy and hinder the growth of recrystallized grains. Among them, Fe element is controlled in the above range to improve the problem that too high Fe content easily affects the surface quality of the product; Mn element is controlled in the above range to improve the problem that too high Mn content easily generates coarse primary crystals of intermetallic compounds; Cr element hinders the nucleation and growth of recrystallization; Ti element refines the casting structure; through the addition of the above elements, the strength and plasticity of aluminum alloy are improved, the comprehensive performance is improved, and its crushing performance is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0117] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0118] Figure 1 A schematic diagram of a method for preparing an aluminum alloy according to an embodiment of the present application;

[0119] Figure 2 This is a schematic structural diagram of an aluminum alloy crushing test according to an embodiment of the present application;

[0120] Figure 3 This is a schematic structural diagram of an aluminum alloy crushing test according to an embodiment of the present application;

[0121] Figure 4 The extrusion force and displacement distance curve of an embodiment of the present application;

[0122] Figure 5 This is a schematic diagram of the crush test of Example 1 of the present application.

[0123] Description of Figure Numbers:

[0124] Label name Label name 10 Support structure 30 Aluminum alloy profiles 11 platform 31 One surface 13 Support plate 32 The other surface 20 Impact parts

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

[0126] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0127] Hereinafter, the aluminum alloy and its preparation method, and the implementation method of the crushing test method of the aluminum alloy of the present application are specifically disclosed in detail with appropriate reference to the drawings. However, there may be cases where unnecessary detailed descriptions are omitted. For example, there are cases where detailed descriptions of well-known matters and repeated descriptions of actually the same structures are omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate the understanding of those skilled in the art. In addition, the drawings and the following descriptions are provided for those skilled in the art to fully understand the present application, and are not intended to limit the subject matter described in the claims.

[0128] "Scope" disclosed in the present application is limited in the form of lower limit and upper limit, and a given range is limited by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundary of a special range. The scope limited in this way can be including end values ​​or not including end values, and can be arbitrarily combined, that is, any lower limit can be combined with any upper limit to form a scope. For example, if the scope of 60-120 and 80-110 is listed for a specific parameter, it is understood that the scope of 60-110 and 80-120 is also expected. In addition, if the minimum range values ​​1 and 2 are listed, and if the maximum range values ​​3, 4 and 5 are listed, the following scope can be all expected: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In the present application, unless otherwise specified, the numerical range "ab" represents the abbreviation of any real number combination between a and b, wherein a and b are real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" are listed in this document, and "0-5" is just an abbreviation of these numerical combinations. In addition, when a parameter is expressed as an integer ≥ 2, it is equivalent to disclosing that the parameter is, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0129] Unless otherwise specified, all embodiments and optional embodiments of the present application can be combined with each other to form a new technical solution.

[0130] Unless otherwise specified, all technical features and optional technical features of this application can be combined with each other to form a new technical solution.

[0131] If there is no special explanation, all steps of the present application can be performed sequentially or randomly, preferably sequentially. For example, the method includes steps (a) and (b), which means that the method may include steps (a) and (b) performed sequentially, or may include steps (b) and (a) performed sequentially. For example, the method may further include step (c), which means that step (c) may be added to the method in any order. For example, the method may include steps (a), (b) and (c), or may include steps (a), (c) and (b), or may include steps (c), (a) and (b), etc.

[0132] Aluminum alloy is the most widely used type of metal structural material in industry.

[0133] During a collision of an aluminum alloy structure, it is usually required to have the function of resisting external impact.

[0134] For example, the profile of safety collision parts needs to have good crushing performance. Take cars as an example. When a car collides, aluminum alloy can absorb the impact energy of the outside world on the car 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 to avoid secondary damage such as fire after the battery is squeezed. Therefore, there are very high performance requirements for automobile anti-collision safety collision parts, especially crushing performance.

[0135] In order to improve the crushing performance of aluminum alloys, the present application provides an aluminum alloy, which includes, 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%; and the balance is Al.

[0136] An alloy is a mixture with metallic properties that is synthesized by a certain method from two or more metals and metals or non-metals.

[0137] La is a metallic rare earth element. The addition amount of La element within the above range can improve the effect of deoxidation and purification of impurities, improve the fluidity of aluminum alloy liquid, refine the aluminum alloy grains, make the organization uniform, and improve the mechanical properties of the aluminum alloy.

[0138] The addition of appropriate amount of Si can improve the casting performance and corrosion resistance of aluminum alloy. The improved casting performance can improve the quality and performance of castings. The addition of appropriate amount of Mg can improve the plasticity of aluminum alloy and improve the crushing performance of aluminum alloy; Fe and Mn elements increase the recrystallization temperature of aluminum alloy and hinder the growth of recrystallized grains. Among them, the Fe element is controlled within the above range to improve the problem that the high mass content of Fe element is easy to affect the surface quality of the product; the Mn element is controlled within the above range to improve the problem that the high mass content of Mn element is easy to generate coarse primary crystals of intermetallic compounds; Cr element hinders the nucleation and growth of recrystallization; Ti element refines the casting structure; through the addition of the above elements, the strength and plasticity of aluminum alloy are improved, the comprehensive performance is improved, and its crushing performance is improved.

[0139] In the above 0.08% to 0.15%, the values ​​include the minimum and maximum values ​​of the range, and 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] In the above 0.55% to 0.65%, the values ​​include the minimum and maximum values ​​of the range, and 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] In the above 0.48% to 0.58%, the values ​​include the minimum and maximum values ​​of the range, and 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., and the range values ​​between any two of the above point values.

[0142] In the above 0.15% to 0.25%, the values ​​include the minimum and maximum values ​​of the range, and 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%, 025, etc., and the range values ​​between any two of the above point values.

[0143] In the above 0.06% to 0.12%, the values ​​include the minimum and maximum values ​​of the range, and 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] In the above 0.05% to 0.10%, the values ​​include the minimum and maximum values ​​of the range, and 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] In order to further improve the strength and plasticity of aluminum alloys, improve their comprehensive properties and improve their crushing properties, the mass percentage of La is controlled to be 0.1% to 0.15%; the mass percentage of Si is 0.57% to 0.62%; the mass percentage of Mg is 0.5% to 0.55%; the mass percentage of Fe is 0.15% to 0.2%; the mass percentage of Mn is 0.19% to 0.24%; the mass percentage of Cr is 0.08% to 0.12%; the mass percentage of Ti is 0.06% to 0.10%; the mass percentage of Zn in aluminum alloy is ≤0.05%; the mass percentage of Cu in aluminum alloy is ≤0.05%. It can be understood that the increase in the mass percentage of Zn and Cu will increase the strength, and the increase in strength will reduce the crushing properties of the aluminum alloy. At the same time, Zn and Cu are relatively expensive, so the mass percentages of Zn and Cu are controlled within the above range.

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

[0148] It is understandable that the finer the grains, that is, the more grains per unit volume, the more grain boundaries, the more tortuous the grain boundaries, the greater the barrier to dislocations, and the higher the strength. At the same time, under the same amount of plastic deformation, the deformation is dispersed in more grains, and the deformation is more uniform; there are fewer dislocations accumulated in each grain, and the chance of cracking due to stress concentration is less, and it can withstand a greater amount of deformation before breaking.

[0149] The strength and crushing performance of aluminum alloys are contradictory. In the preparation process, high strength often corresponds to low folding effect, and high folding effect often corresponds to low strength. The strength and crushing performance are contradictory. By adding appropriate amounts of the above elements, the crushing performance can be improved while improving the strength of the aluminum alloy, that is, the crushing performance can be improved while meeting the structural strength requirements.

[0150] like Figure 1 As shown, the present application also provides a method for preparing an aluminum alloy, comprising: preparing a formula component of the aluminum alloy to obtain a raw material; melting, refining, degassing, deslagging, and casting the raw material to obtain an aluminum alloy molten casting.

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

[0152] Cast aluminum alloys have strong hydrogen absorption capacity, resulting in more needle-shaped pore defects. At the same time, during the casting process, defects such as inclusions, shrinkage cavities, and shrinkage porosity will also be produced. These casting defects seriously reduce the physical, chemical and mechanical properties of cast aluminum alloys. In order to overcome these casting defects, after the raw materials are melted, they will be refined, degassed, and deslag treated to reduce or eliminate casting pores.

[0153] In one embodiment, after the raw materials are melted, refined, degassed, deslagged, and cast to obtain an aluminum alloy casting, the following steps are also included: homogenizing the aluminum alloy casting, and the homogenization conditions are: a holding temperature of 575°C±10°C and a holding time of 6h to 8h.

[0154] Homogenization treatment, also known as homogenization annealing, is a process in which the alloy ingot is heated to a temperature close to the unbalanced solidus temperature for a long time and then slowly cooled to room temperature. Its purpose is to eliminate or reduce the heterogeneity of the chemical composition and organization of the alloy through the diffusion of alloy element atoms, improve the internal organization of the ingot, eliminate the residual stress of the ingot, improve the mechanical processing performance of the ingot, and at the same time improve the plasticity, reduce the deformation resistance, and improve the thermal processing performance of the alloy.

[0155] In order to improve the performance of the alloy, after obtaining the aluminum alloy molten casting, the alloy molten casting is also homogenized. The homogenization treatment can improve the internal structure of the alloy, improve the residual stress, improve the mechanical processing performance, increase the plasticity, reduce the deformation resistance, and improve the processing performance of the alloy.

[0156] In order to improve the performance of aluminum alloy castings, the holding temperature of the homogenization treatment is 575℃±10℃, and the holding time is 6h to 8h.

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

[0158] In the above 6h to 8h, the values ​​include the minimum and maximum values ​​of the range, and every value between the minimum and maximum values. Specific examples include but are not limited to the point values ​​in the embodiments and 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 the aluminum alloy casting is homogenized, a cooling step is further included, and the cooling conditions are: wind and mist cooling to a temperature greater than or equal to 200° C. and less than 250° C., and then water cooling to room temperature. Room temperature refers to the temperature of the current environment, which varies according to each place, season, or workshop, and is not specifically limited. For example, the room temperature can be 10° C. to 50° C.

[0160] The present application adopts a wind and mist cooling method. Wind and mist cooling refers to generating atomized water vapor through a wind and 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 retaining the structure of the aluminum alloy casting in a high temperature state. Rapid cooling can also shorten the processing time.

[0161] In the above-mentioned temperature greater than or equal to 200°C and less than 250°C, the values ​​include the minimum and maximum values ​​of the range, and 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., and the range values ​​between any two of the above-mentioned point values.

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

[0163] The steps of melting, refining, degassing, deslagging and casting the raw materials to obtain aluminum alloy castings include: melting Al in a smelting furnace at a melting temperature of 710°C to 750°C, adding Fe, Mn, Cr, Si, La, and melting them, and adding Mg to melt them to obtain molten aluminum A; refining, degassing and deslagging the molten aluminum A; adding aluminum-titanium wire to melt it to obtain molten aluminum B; and casting the molten aluminum B.

[0164] In this application, the raw materials are fed into the smelting furnace in steps, and the order of feeding the raw materials not only affects the melting efficiency and alloy consumption, but also directly affects the quality of the aluminum alloy liquid. The above-mentioned feeding steps can improve the melting efficiency and reduce the alloy consumption.

[0165] When charging the smelting furnace, first load small pieces or thin sheets of waste, then load aluminum ingots and large pieces in the middle, and finally load the master alloy. The easily oxidized master alloy is loaded in the middle and lower layers. The loaded furnace charge should be evenly distributed in the molten pool to prevent overweight. The small pieces or thin sheets of waste are loaded in the lower layer of the molten pool to reduce burning loss and protect the furnace body from direct impact and damage of large pieces. It can be understood that when adding Fe, Mn, Cr, Si, and La to the smelting furnace, these metals can be added in the form of alloys, such as Al-Fe, Al-Mn, Al-Cr, Al-Si, and Al-La. The Al-Mn master alloy added in this scheme has a relatively high melting point (750℃-800℃) and should be loaded in the upper layer. The temperature in the upper part of the furnace is high and easy to melt, and there is also time to fully diffuse, so that the master alloy is evenly distributed, which is conducive to the control of the composition of the solution.

[0166] The charge is leveled, and the melting speeds of different places are similar, which can prevent local metal overheating caused by heavy loads. The above charging method not only reduces the burning loss, but also increases the melting speed, which is beneficial to the composition control. At the same time, the temperature fluctuation in the furnace is not large, which has a good protection effect on the furnace bottom and is beneficial to increase the furnace life.

[0167] In the above-mentioned 710℃ to 750℃, the values ​​include the minimum and maximum values ​​of the range, and 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-mentioned point values.

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

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

[0170] Refining is the process of removing impurities from the melt. It is understandable that the slag and gas content of the Al liquid increases, and the chemical composition changes, resulting in pinholes, oxidation slag, shrinkage and unqualified chemical composition in the casting, affecting the quality of the casting. In order to obtain qualified aluminum alloy castings, the above refining conditions are adopted. Furnace refining is mainly achieved by using granular refining agents to absorb slag inclusions and float them to the surface of the aluminum solution, making the aluminum liquid purer and reducing defects such as pores, slag inclusions, and looseness in the aluminum rod.

[0171] It is understandable that the sodium-free refining agent in the present application is not specifically limited, and includes, for example, 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 double-rotor degassing box.

[0173] Aluminum alloys absorb hydrogen during the melting process. For example, the source of hydrogen includes the reaction between aluminum alloy liquid and water vapor. Hydrogen absorption causes pinholes in aluminum alloy castings, reduces air tightness and mechanical properties. In order to improve the performance of aluminum alloy castings, hydrogen is removed through a degassing step. Refining aluminum alloys by blowing argon, for example, using online degassing, using a double-rotor degassing box to rotate and blow argon to refine aluminum alloys, can remove hydrogen and slag inclusions, purify aluminum liquid, and achieve the purpose of eliminating pinholes in castings.

[0174] Its working principle is that when the motor drives the rotor to rotate (usually the speed is 380 rpm-450 rpm), argon gas (flow rate is 0.5m3 / hour -1.5m 3 / hour) is beaten into very small bubbles. The existence of these small bubbles reduces the concentration of hydrogen in the aluminum liquid and the partial pressure on its surface, thereby reducing the concentration of hydrogen in the aluminum liquid, so that the hydrogen is brought to the surface of the aluminum liquid by argon and burned and consumed on the liquid surface.

[0175] When the small argon bubbles move from the bottom of the aluminum liquid to the surface, the hydrogen dissolved in the aluminum liquid changes from a dissolved state to an adsorbed state when it hits the argon-aluminum liquid interface. The gas atoms in the adsorption layer react to generate hydrogen molecules, which rise to the surface of the aluminum liquid and burn as the bubbles grow. In addition, when the small argon bubbles move from the bottom of the aluminum liquid to the surface, the suspended inclusion particles in the aluminum liquid are stirred, and the inclusions collide, aggregate and grow. When the inclusions reach a certain size, they may collide with the floating bubbles, be captured, and then be brought to the liquid surface to achieve the effect of slag removal. Reduce defects such as pores, slag inclusions, and looseness in aluminum bars.

[0176] The conditions for removing slag are: using a filter plate to filter and remove slag.

[0177] Aluminum alloy raw materials will absorb gas and oxidize during the melting process, forming oxidized slag inside or on the surface of the aluminum alloy liquid. The oxidized slag is easily adsorbed by the gas in the aluminum alloy liquid, making it difficult for the gas to precipitate from the aluminum alloy liquid. The presence of gas and oxidized slag in the aluminum alloy liquid leads to defects such as pores and slag inclusions in the aluminum alloy castings. In order to improve the performance of aluminum alloy castings, the slag in the aluminum alloy liquid is removed through a slag removal process. For example, a 40-60 mesh double-stage filter plate can be used for filtration.

[0178] The casting conditions are as follows: the B aluminum liquid is molded and cast through a hot top casting machine. During the casting process, the temperature of the B aluminum liquid reaching the casting plate is controlled at 700°C to 720°C, and the casting speed of the casting machine is 100mm / min to 130mm / min.

[0179] Melting and casting refers to making aluminum alloy liquid into a solid alloy of a certain shape under certain conditions. For example, the aluminum alloy liquid is poured into a mold for casting; the mold is equipped with a water cooling system, the cooling speed can be controlled during the casting process, argon gas protection is used during the casting process, and the mold after casting is cooled and formed to obtain an aluminum alloy casting. In order to eliminate the problems of uneven structure, coarse grains, and component segregation of aluminum alloy castings, the above-mentioned melting and casting conditions are adopted.

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

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

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

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

[0184] In the above 100mm / min to 130mm / min, the values ​​include the minimum and maximum values ​​of the range, and every value between the minimum and maximum values. Specific examples include but are not limited to the point values ​​in the embodiments and 100mm / min, 110mm / min, 120mm / min, 130mm / 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 cast structure grains of the aluminum alloy obtained after the melting and casting is ≤150um.

[0186] As-cast structure refers to the microstructure formed when the metal (mostly alloy) material is transformed from a molten metal to a solid during the smelting process. Through the above process conditions, the average grain size range of the as-cast structure grains of the aluminum alloy obtained after melting and casting is within the above range. The as-cast structure grains are fine, which helps to improve the strength and plasticity of the aluminum alloy and improve the crushing performance of the aluminum alloy during impact extrusion.

[0187] Measurement of organizational grains: Refer to GB / T 3246.1 Organization test methods for deformed aluminum and aluminum alloy products Part 1: Microstructure test methods.

[0188] In one embodiment, after the raw material is melted, refined, degassed, deslaged, and cast 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 plastic, aluminum, fiberglass, etc.) through rolling, extrusion, casting and other processes.

[0190] In order to obtain aluminum alloy profiles with suitable size and performance, the prepared aluminum alloy molten casting can be heated, extruded, quenched and cut to obtain aluminum alloy profiles.

[0191] The heating step is to soften the aluminum alloy casting to facilitate subsequent extrusion deformation. The extrusion step is to hot extrude the heated aluminum alloy casting through an extruder to form it into a certain shape. Quenching refers to a metal heat treatment process in which a metal workpiece is heated to a certain temperature and maintained for a period of time, and then immersed in a quenching medium for rapid cooling. Quenching can improve the performance of aluminum alloys. Cutting refers to using cutting tools to cut aluminum alloys into aluminum alloy profiles of a certain size.

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

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

[0194] After stretching and straightening treatment, the internal stress of aluminum alloy can be improved, thereby improving the strength, stress corrosion resistance and structural dimensional stability of aluminum alloy.

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

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

[0197] In order to improve the toughness of aluminum alloy and improve the problem of easy rupture and failure of aluminum alloy during extrusion, the aluminum alloy is subjected to aging treatment after cutting. That is, in order to eliminate the residual stress generated inside the aluminum alloy profile, stabilize its shape, size, strength and hardness, and stably improve the final mechanical properties of the aluminum alloy profile.

[0198] In one embodiment, the conditions for heating and extruding the aluminum alloy casting are: heating the extrusion die to 470°C to 500°C, keeping it warm for 4h to 12h, heating the aluminum alloy casting to 460°C to 500°C and extruding it at an extrusion speed of 1.5mm / s to 5.0mm / s.

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

[0200] In order to refine the grain size of the extruded structure, the extrusion conditions are as follows: heating the extrusion die to 470°C to 500°C, keeping it warm for 4h to 12h, and heating the aluminum alloy casting to 460°C to 500°C and extruding it at an extrusion speed of 1.5mm / s to 5.0mm / s.

[0201] It is understandable that the heating temperature and extrusion speed comprehensively control the quenching temperature of the discharge port. In order to ensure production efficiency, the extrusion speed is generally accelerated as much as possible under the premise of the mold allowing. The faster the speed, the higher the friction heat between metal and metal, metal and mold (extrusion temperature rise), the higher the discharge port temperature will be. Too high a temperature will cause the profile structure to be coarse grains or even cracks. Therefore, it is necessary to appropriately reduce the heating temperature of the aluminum alloy casting to balance the quenching temperature of the discharge port. For this purpose, the heating temperature is 460℃ to 500℃.

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

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

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

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

[0206] In one embodiment, the average grain size of the grains in the extruded structure after extrusion ranges from 80 μm to 120 μm.

[0207] In the above-mentioned 80μm to 120μm, the values ​​include the minimum and maximum values ​​of the range, and 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-mentioned point values.

[0208] Through the above steps, the average grain size of the extruded grains of the present invention after extrusion meets the above range. The refined extruded grains help to improve the strength and plasticity of the aluminum alloy and improve the crushing performance of the aluminum alloy during impact extrusion.

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

[0210] In order 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 method includes spray cooling or water cooling.

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

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

[0214] It can be understood that water-through cooling refers to cooling by a water-through cooling device, which includes a water cooling box with water inlet and outlet pipes. Cooling water is sprayed out from the water inlet pipe, collected by the water cooling box, and discharged through the drain port at the lower end of the water cooling box, thereby realizing circulation and preventing the water temperature in the water cooling box from being too high and affecting the quenching effect.

[0215] In the above-mentioned 500℃ to 535℃, the values ​​include the minimum and maximum values ​​of the range, and 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-mentioned point values.

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

[0217] Stretching and straightening can improve the internal stress of aluminum alloy. In order to improve the performance, the elongation of stretching and straightening is 0.5 to 1.3 times. Elongation = (length after stretching - length before stretching) / length before stretching * 100%. Stretching and straightening can eliminate the irregular shape in the longitudinal direction and reduce its residual stress. The elongation range is 0.5% to 1.3%. If the elongation is too low, it will not have the effect of straightening and eliminating internal stress. If the elongation is too high, it will cause the plasticity of the profile to decrease, the surface will be orange peel, local thinning or the size will exceed the tolerance range.

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

[0219] In order to improve the toughness of aluminum alloy, the aging treatment conditions include over-aging treatment, the over-aging treatment temperature is 205℃ to 210℃, and the holding time is 4.5h to 6h. Under certain temperature conditions, the aging holding time exceeds the peak aging time, or the holding temperature exceeds the peak holding temperature, the precipitated phase inside the material begins to grow, the spacing becomes larger, and the macroscopic performance is that the strength of the material is reduced and the plastic toughness is improved.

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

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

[0222] The present application also provides a crush test method for aluminum alloys, comprising: fixing the aluminum alloy on a support structure; controlling an impact piece to extrude along the surface of the aluminum alloy profile, the impact piece applying an extrusion force to the aluminum alloy along a first direction, and the support structure being used to provide a restraining reaction force for the aluminum alloy; the aluminum alloy includes the aluminum alloy as described above, or the aluminum alloy includes an aluminum alloy obtained by the aluminum alloy preparation method as described above.

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

[0224] like Figure 2 As shown, in order to test the crushing performance of the aluminum alloy, the aluminum alloy profile 30 is fixed to the support structure 10, and the impact piece 20 is controlled to be extruded along the surface of the aluminum alloy profile 30. The impact piece 20 applies an extrusion force to the aluminum alloy profile 30 along a first direction, and the support structure 10 is used to provide a restraining reaction force for the aluminum alloy. In this way, the aluminum alloy profile can be sandwiched between the support structure 10 and the impact piece 20 and subjected to the extrusion force. After the aluminum alloy profile 20 is subjected to the extrusion force, the shape of the aluminum alloy profile can be observed to judge the crushing performance of the aluminum alloy profile.

[0225] In one embodiment, in the step of fixing the aluminum alloy on the support structure, the support structure includes a platform and a support plate erected on the platform, the aluminum alloy is arranged 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 be against the platform 11 and the support plate 13 to improve the stability of the installation of the aluminum alloy profile. 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, in the step of controlling the impact piece to extrude along the surface of the aluminum alloy, the extrusion direction of the impact piece is toward the platform or the support plate.

[0228] In order to test the crushing properties of multiple surfaces of aluminum alloy profiles, for example Figure 3As shown, the impact piece 20 can be controlled to extrude the aluminum alloy profile 30 toward the direction where the platform 11 is located, so that the aluminum alloy profile 30 is extruded by the platform 11 and the impact piece 20, and the crushability test of the aluminum alloy profile parallel to a surface 31 of the platform 11 is realized. Figure 2 As shown, the impact piece 20 can also be controlled to extrude the aluminum alloy profile toward the direction of the support plate 13, so that the aluminum alloy profile 30 is extruded by the support plate 13 and the impact piece 20, thereby achieving a crushability test of the aluminum alloy profile parallel to the other surface 32 of the support plate 13.

[0229] In particular, when aluminum alloy is used in automobile profiles, the crushability during a car collision is simulated. Generally, the side of the profile is squeezed by the collision. In order to simulate the extrusion of the side of the aluminum alloy, the side of the aluminum alloy can be facing the extrusion direction of the impact part.

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

[0231] In order to conveniently record the extrusion pressure of the impact piece, a first pressure sensor is provided at the end of the impact piece facing the aluminum alloy, and the extrusion pressure can be obtained from the first pressure sensor during the extrusion process. Of course, a second pressure sensor can also be provided at the portion of the platform where the aluminum alloy is set, and when the impact piece extrude the aluminum alloy in the direction where the platform is located, the extrusion pressure can also be obtained from the second pressure sensor. A third pressure sensor can also be provided at the portion of the support plate where the aluminum alloy is set, and when the impact piece extrude the aluminum alloy in the direction where the support plate is located, the extrusion pressure can also be obtained from the third pressure sensor.

[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, the extrusion pressure is defined as F1, the extrusion pressure-displacement distance data of the test is extracted, the extrusion pressure-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.

[0233] Energy absorption performance refers to the fact that in the crush test of aluminum alloy, wrinkles are produced at the extruded part, which can absorb a large amount of impact energy. In fact, the design of energy absorption is to consume energy by using the deformation of the structure. When a collision occurs, the deformation of the energy absorption area consumes part of the energy, ensuring that the energy transmitted to the driving area or the battery area is less than the bearing capacity of the structure without deformation, so as to better ensure the safety of passengers or batteries.

[0234] After aluminum alloy is extruded, the extruded part will be deformed under stress. In order to calculate the energy absorption performance of aluminum alloy, the displacement distance of the surface of the extruded part of aluminum alloy before and after extrusion is obtained as H1, and the extrusion force is F1. The extrusion force and displacement distance data of the test are 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. Figure 4 As shown, it is an extrusion force-displacement distance curve in one embodiment, and the area enclosed between the 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 is in a range of 50 mm / min to 100 mm / min.

[0236] The present application does not limit the shape of the impact head of the impact piece. In order to prevent the angular impact head from damaging the aluminum alloy during the extrusion process, the impact head is preferably spherical or hemispherical.

[0237] The loading speed of the impact piece in the present application ranges from 50 mm / min to 100 mm / min.

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

[0239] Example

[0240] Example 1

[0241] Prepare raw materials: Al, Mg, Al-Si master alloy, La, Fe, Cr, Ti, Mn, according to the alloy composition. The final alloy is La: 0.12%, Si: 0.6%, Mg: 0.5%, Fe: 0.2%, Mn: 0.2%, Cr: 0.1%, Ti: 0.07%, and the rest is Al. The individual content of other inevitable impurities is less than 0.05%, and the total amount is less than 0.15%.

[0242] Aluminum alloy preparation process steps:

[0243] When the smelting temperature is 725°C, Al is melted in a smelting furnace, and Fe, Mn, Cr, the Si, the La are added to melt, and the Mg is added to melt to obtain molten aluminum A; the molten aluminum A is refined, degassed, and deslag treated; aluminum-titanium wire is added to melt to obtain molten aluminum B; the molten aluminum B is melted and cast.

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

[0245] The double rotor degassing box is used for online degassing, the rotor speed is 400 rpm, and the argon flow rate is 1m 3 / hour. A 50-mesh filter plate was used to filter and remove slag. The B aluminum liquid was cast by a hot top casting machine. During the casting process, the temperature of the B aluminum liquid reaching the casting plate was controlled at 710°C, and the casting speed of the casting machine was 115 mm / min.

[0246] The aluminum alloy castings obtained after melting and casting are homogenized under the following conditions: insulation temperature of 575°C ± 10°C for 7 hours, followed by wind and mist cooling to 220°C and water cooling to 25°C.

[0247] The aluminum alloy casting after homogenization is heated at a heating temperature of 480°C.

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

[0249] Then quenching is performed, and the quenching steps are: spray cooling is adopted, the quenching temperature range is 510°C, and the cooling intensity is 8°C / s.

[0250] Then, stretching and straightening are performed, and the elongation of the stretching and straightening is 1.0%.

[0251] Then cut.

[0252] Then carry out aging treatment, the aging treatment steps are: the aging treatment temperature is 205℃, and the insulation time is 4h.

[0253] Example 2 to Example 3

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

[0255] Example 4

[0256] Based on Example 1, no aging treatment was performed.

[0257] Example 5

[0258] On the basis of Example 1, no stretching and straightening was performed.

[0259] Example 6

[0260] On the basis of Example 1, no homogenization treatment was performed and the mixture was cooled naturally.

[0261] Comparative Example 1 to Comparative Example 3

[0262] Comparative Examples 1 to 3 are 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 is fixed on the support structure, and the impact piece is controlled to extrude along the side of the aluminum alloy profile. The loading speed of the impact piece (pressure head) is 100mm / min. The displacement distance of the surface of the extruded part of the aluminum alloy profile before and after extrusion is measured as H1, and the extrusion force is F1. The force and displacement data of the test are extracted. The fixed displacement distance of this test is set to 35mm, 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. The extrusion force is measured using a strain sensor, and the sensor error does not exceed 2% within the range. Observe and record the deformation results and force-displacement data, and observe and record the surface conditions of the wrinkle position of the crushed sample.

[0266] Table 1 Experimental data list

[0267]

[0268]

[0269] It can be seen from the above table that the energy absorption performance of the aluminum alloy prepared by the aluminum alloy formula of the present application is improved.

[0270] The above are only preferred embodiments of the present invention, and are not intended to limit the patent scope of the present invention. All equivalent structural changes made using the contents of the present invention's specification and drawings, or directly / indirectly applied in other related technical fields, are included in the patent protection scope of the present invention.

Claims

1. An aluminum alloy, characterized in that: Calculated 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.

2. The aluminum alloy according to 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 according to claim 1 or 2, characterized in that: include: Preparing a formula component of an aluminum alloy to obtain a raw material; The raw materials are melted, refined, degassed, deslagged, and cast to obtain aluminum alloy castings.

4. The method for preparing an aluminum alloy according to claim 3, characterized in that: After the raw materials are melted, refined, degassed, deslagged, and cast to obtain aluminum alloy castings, the following steps are also included: The aluminum alloy casting is homogenized, and the homogenization conditions are: a holding temperature of 575°C±10°C and a holding time of 6h to 8h.

5. The method for preparing an aluminum alloy according to claim 4, characterized in that: After the aluminum alloy casting is homogenized, a cooling step is also included. The cooling conditions are: wind and mist cooling to a temperature greater than or equal to 200° C. and less than 250° C., and then water cooling to room temperature.

6. The method for preparing an aluminum alloy according to any one of claims 3 to 5, characterized in that: The steps of melting, refining, degassing, deslagging and casting the raw materials to obtain aluminum alloy castings include: When the smelting temperature is 710° C. to 750° C., the Al is melted in a smelting furnace, and the Fe, Mn, Cr, Si, and La are added and melted, and the Mg is added and melted to obtain aluminum liquid A; The A aluminum liquid is subjected to refining, degassing and deslagging treatments; Aluminum titanium wire is added to melt to obtain aluminum liquid B; The B aluminum liquid is melted and cast.

7. The method for preparing an aluminum alloy according to any one of claims 3 to 6, characterized in that: The refining conditions are: using argon and sodium-free refining agent for refining, the amount of sodium-free refining agent used is 1.8kg to 2.2kg 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: online degassing using a dual-rotor degassing box; And / or, the condition for removing slag is: filtering and removing slag by using a filter plate.

8. The method for preparing an aluminum alloy according to claim 6, wherein: The conditions for the melting and casting are: the B aluminum liquid is molded and cast by a hot top casting machine. During the casting process, the temperature of the B aluminum liquid reaching the casting plate is controlled at 700°C to 720°C, and the casting speed of the casting machine is 100mm / min to 130mm / min.

9. The method for preparing an aluminum alloy according to any one of claims 3 to 8, characterized in that: The average grain size range of the cast structure grains of the aluminum alloy obtained after melting and casting is ≤150um.

10. The method for preparing an aluminum alloy according to any one of claims 3 to 9, characterized in that: After the raw materials are melted, refined, degassed, deslagged, and cast to obtain aluminum alloy castings, the method further includes: The aluminum alloy molten casting is heated, extruded, quenched and cut to obtain an aluminum alloy profile.

11. The method for preparing an aluminum alloy according to claim 10, characterized in that: The step of heating, extruding, quenching and cutting the aluminum alloy casting to obtain an aluminum alloy profile comprises: The aluminum alloy casting is heated, extruded, quenched, stretched, straightened and cut to obtain aluminum alloy profiles.

12. The method for preparing an aluminum alloy according to claim 10 or 11, characterized in that: The steps of heating, extruding, quenching and cutting the aluminum alloy casting to obtain the aluminum alloy profile include: The aluminum alloy casting is heated, extruded, quenched, cut, and subjected to aging treatment to obtain an aluminum alloy profile.

13. The method for preparing an aluminum alloy according to any one of claims 10 to 12, characterized in that: The conditions for heating and extruding the aluminum alloy casting are: heating the extrusion die to 470° C. to 500° C., keeping it warm for 4 h to 12 h, 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.

14. The method for preparing an aluminum alloy according to any one of claims 10 to 13, characterized in that: The average grain size of the grains in the extruded state structure after extrusion ranges from 80 μm to 120 μm.

15. The method for preparing an aluminum alloy according to any one of claims 10 to 14, characterized in that: The quenching conditions are: the quenching temperature range is 500°C to 535°C, and the cooling intensity is ≥8°C / s; And / or, the quenching method includes spray cooling or water cooling.

16. The method for preparing an aluminum alloy according to claim 11, characterized in that: During the stretching and straightening process, the stretching elongation is 0.5% to 1.3%.

17. The method for preparing an aluminum alloy according to claim 12, wherein: The aging treatment conditions include over-aging treatment, the over-aging treatment temperature is 205° C. to 210° C., and the insulation time is 4.5 h to 6 h.

18. A crush test method for aluminum alloy, characterized in that: include: Fixing the aluminum alloy to the supporting structure; Controlling the impact piece to extrude along the surface of the aluminum alloy, the impact piece applies an extrusion force to the aluminum alloy along a first direction, and the support structure is used to provide a restraining reaction force for the aluminum alloy; The aluminum alloy includes the aluminum alloy as claimed in claim 1 or 2, or the aluminum alloy includes the aluminum alloy obtained by the method for preparing the aluminum alloy according to any one of claims 3 to 17.

19. The crush test method for aluminum alloy according to claim 18, characterized in that: In the step of fixing the aluminum alloy on the support structure, the support structure includes a platform and a support plate erected on the platform, the aluminum alloy is arranged on the platform and abuts against the support plate, and the aluminum alloy is fixed to the platform and / or the support plate.

20. The crush test method for aluminum alloy according to claim 18 or 19, characterized in that: In the step of controlling the impact piece to extrude along the surface of the aluminum alloy, the extrusion direction of the impact piece is toward the platform or the support plate.

21. The crush test method for an aluminum alloy according to any one of claims 18 to 20, characterized in that: The end of the impact piece facing the aluminum alloy is provided with a first pressure sensor; And / or, a second pressure sensor is provided at a position of the platform where the aluminum alloy is provided; And / or, a third pressure sensor is provided at a portion of the support plate where the aluminum alloy is provided.

22. The crush test method for an aluminum alloy according to any one of claims 18 to 21, characterized in that: 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 pressure is defined as F1. The extrusion pressure and displacement distance data of the test are extracted, and the extrusion pressure and displacement distance curves are 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.

23. The crush test method for an aluminum alloy according to any one of claims 18 to 22, characterized in that: The impact head of the impact piece is spherical or hemispherical; And / or, the loading speed of the impact piece ranges from 50 mm / min to 100 mm / min.

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