Aluminum alloy for liquid die forging, preparation method of aluminum alloy and manufacturing application of liquid die forging workpiece

Abstract

The invention relates to the technical field of aluminum alloy materials and casting, and provides an aluminum alloy for liquid die forging, a preparation method of the aluminum alloy and liquid die forging workpiece manufacturing application, and the aluminum alloy for liquid die forging comprises, by mass, 6.0%-10.0% of Si, 0.3%-1.0% of Mg, 0.05%-0.8% of Mn, 0.05%-0.6% of Cr, 0.005%-0.05% of Ga, 0.01%-0.2% of Hf, 0.01%-0.2% of W, 0.03%-0.4% of Y, 0.03%-0.4% of Nd, 0.03%-0.4% of Er and the balance aluminum. The aluminum alloy comprises the following components in percentage by weight: less than or equal to 1.0% of Fe, less than or equal to 0.25% of Hf and W elements, 0.2-0.8% of Y, Nd and Er elements, less than or equal to 0.03% of other inevitable single impurity elements, less than or equal to 0.15% of impurity elements and the balance of aluminum. The aluminum alloy for liquid die forging effectively solves the problems that the formability and the mechanical property of an existing material are difficult to consider at the same time and the cost controllability is poor, and has remarkable comprehensive advantages.

Description

Technical Field

[0001] This invention relates to the field of aluminum alloy materials and casting technology, specifically to an aluminum alloy for liquid forging, its preparation method, and its application in the manufacture of liquid forged workpieces. Background Technology

[0002] Liquid forging is a composite forming process that combines the advantages of casting and forging. Its core principle is to directly pour a measured amount of molten metal into a mold cavity, and apply high mechanical pressure through a punch, causing the liquid or semi-liquid metal to complete filling, solidification, and plastic deformation under pressure, ultimately forming the target part. This technology, through the synergistic effect of pressure and deformation, can significantly optimize the internal quality of aluminum alloy products. It can not only refine grains and improve microstructure density, but also effectively reduce casting defects such as porosity, looseness, and shrinkage cavities, giving the workpiece excellent comprehensive mechanical properties of both high strength and high plasticity.

[0003] Leveraging these advantages, liquid forging technology is widely used in the manufacturing of parts with stringent requirements for airtightness and pressure resistance, particularly in automotive components such as brake calipers, steering knuckles, hydraulic joints, engine pistons, and wheel hubs, as well as industrial components like hydraulic valve blocks, pump bodies, and cylinder end caps. Furthermore, this technology exhibits excellent compatibility with wrought aluminum alloys that suffer from poor liquid flowability and casting fillability, covering the processing of wrought aluminum alloys in multiple systems, including 2024, 3003, 6061, 6082, and 7075. It fills the technological gap between the low performance of traditional casting and the limited shape possibilities of traditional forging, becoming an important component of advanced manufacturing. In the current industrial context of pursuing lightweighting, high performance, and sustainable development, the application prospects of liquid forging technology are increasingly broad.

[0004] Aluminum alloys have become a key material in the automotive industry, especially in the field of new energy vehicles, where the application rate of aluminum products is significantly higher than in traditional vehicles. With consumers' increasing demands for vehicle safety, economy, and lightweighting, the automotive industry's need for high-performance aluminum alloys is becoming increasingly urgent, leading to significant industry attention on liquid forging technology. However, the aluminum alloys commonly used in current liquid forging processes are mainly aluminum-silicon cast aluminum alloys such as A356, A380, and ADC12. While these materials possess excellent castability and can achieve good mechanical properties after heat treatment, they generally suffer from poor plasticity, making it difficult to meet the automotive industry's further lightweighting needs.

[0005] In addition to the plasticity issues of mainstream materials, existing liquid forged aluminum alloy materials also have many limitations: some formulations that rely on scrap aluminum as raw material are prone to iron enrichment and coarse iron-rich phases due to repeated recycling of scrap aluminum, which directly reduces the mechanical properties of the workpiece; while some alloys that pursue high strength achieve this goal by increasing the copper and magnesium content, but this leads to a sharp decrease in plasticity. In automotive parts subjected to alternating loads, this can easily cause unpredictable brittle fracture accidents, seriously affecting service reliability.

[0006] Therefore, developing high-performance aluminum alloy materials that combine complex shape formability, high yield strength, excellent plasticity, and controllable cost has become a key technological requirement to support the development of the automotive industry, especially the new energy vehicle industry. Summary of the Invention

[0007] In view of the above-mentioned shortcomings of the existing technology, the present invention provides an aluminum alloy for liquid forging, its preparation method and its application in the manufacture of liquid forging workpieces.

[0008] To achieve the above objectives, the present invention provides the following technical solution: In a first aspect, an aluminum alloy for liquid forging is provided, comprising, by mass percentage: Si: 6.0%–10.0%, Mg: 0.3%–1.0%, Mn: 0.05%–0.8%, Cr: 0.05%–0.6%, Ga: 0.005%–0.05%, Hf: 0.01%–0.2%, W: 0.01%–0.2%, Y: 0.03%–0.4%, Nd: 0.03%–0.4%, Er: 0.03%–0.4%; The composition is as follows: Fe ≤ 1.0%, total Hf and W ≤ 0.25%, total Y, Nd and Er range from 0.2% to 0.8%, other unavoidable single impurity elements ≤ 0.03%, total impurity elements ≤ 0.15%, and the balance is aluminum.

[0009] In some embodiments, the composition, by mass percentage, includes: Si: 6.5%–8.5%, Mg: 0.4%–0.8%, Mn: 0.1%–0.6%, Cr: 0.08%–0.4%, Ga: 0.008%–0.04%, Hf: 0.03%–0.18%, W: 0.03%–0.18%, Y: 0.05%–0.3%, Nd: 0.05%–0.3%, Er: 0.05%–0.3%. Among them, Fe≤0.8%, the total amount of Hf and W elements≤0.25%, the total amount of Y, Nd and Er elements ranges from 0.2% to 0.8%, other unavoidable single impurity elements≤0.03%, the total amount of impurity elements≤0.15%, and the balance is aluminum.

[0010] In some embodiments, the Fe element content is ≤0.8%, wherein the Fe introduced by the raw materials does not exceed 0.8%, and the additional Fe added is 0.

[0011] Secondly, a method for preparing an aluminum alloy for liquid forging is provided, comprising: Weigh the raw materials according to the formula; The raw materials are refined multiple times, with stirring during the process, until the content of all elements reaches the content required by the formula, to obtain a refined melt. The refined melt is subjected to a two-stage filtration process and then cast to obtain the liquid forging aluminum alloy ingot.

[0012] In some embodiments, the operating parameters for the multiple refining processes include: The first refining process uses high-purity argon gas to inject a remelting refining agent. The amount of the remelting refining agent is 0.1% to 0.5% of the total amount of material in the furnace. The refining time is 20 min to 40 min, and the refining temperature is 720℃ to 860℃. The second refining process uses high-purity argon gas to inject a remelting refining agent. The amount of the remelting refining agent is 0.1% to 0.3% of the total amount of material in the furnace. The refining time is 10 min to 30 min, and the refining temperature is 700℃ to 800℃. Thirdly, a method for manufacturing a liquid forged workpiece is provided, comprising: The liquid forging aluminum alloy is heated, remelted, and stirred to obtain a remelted melt. The liquid forging aluminum alloy is prepared by the preparation method of liquid forging aluminum alloy described in any of the above embodiments. The remelted melt is refined, allowed to stand, slag is removed, and the melt is kept warm to obtain a refined melt. The refined melt is liquid-forged into shape, and after being removed and cooled, a workpiece prepared by liquid forging is obtained; The workpiece prepared by liquid forging is subjected to solution treatment and artificial aging treatment. After the treatment, it is taken out and cooled to room temperature by strong air cooling to obtain the liquid forged workpiece.

[0013] In some embodiments, the operating parameters of the liquid forging process include: The temperature of the molten aluminum is 650℃~720℃, the temperature of the mold is 200℃~300℃, the specific pressure is 50MPa~200MPa, the filling speed of the molten aluminum is 0.01m / s~0.50m / s, and the holding time is 8s~40s.

[0014] In some embodiments, the operating parameters of the solution treatment include: The heating rate is 1℃ / min to 10℃ / min, the holding temperature is 500℃ to 600℃, the holding time is 1h to 8h, the cooling method is water cooling, and the cooling water temperature is 40℃ to 80℃.

[0015] In some embodiments, the operating parameters of the manual aging process include: The heating rate is 1℃ / min to 10℃ / min, the holding temperature is 120℃ to 200℃, and the holding time is 2h to 14h.

[0016] Fourthly, the application of the aluminum alloy for liquid forging described in any of the above embodiments in liquid forging is provided.

[0017] Compared with the prior art, the beneficial effects of the present invention are: by optimizing the composition ratio, the Si element in the alloy forms a hypoeutectic alloy of Al-Si system, which exhibits excellent fluidity and low thermal shrinkage rate in the liquid state, thereby accurately filling cavities with various complex shapes and drastic changes in wall thickness, and greatly improving the molding integrity and pass rate of complex parts. In terms of mechanical properties, Mg can form a metastable β” phase with Si during artificial aging, precipitating from the supersaturated solid solution. Hf and W can form intermediate phases in the alloy, acting as grain boundaries and thus improving the strength of the aluminum alloy. Y, Nd, and Er can form intermediate phases such as Al3Y, Al3Nd, and Al3Er in the aluminum alloy. The crystal structure of these intermediate phases is the same as that of α-Al, which is face-centered cubic, thus refining the grains. Furthermore, under the high cooling rate provided by liquid forging, Y, Nd, and Er will generate supersaturation within the matrix grains, forming nanoscale precipitates, which can hinder dislocation slip. Therefore, by utilizing the dispersed precipitation of strengthening phases during aging, the grain boundary pinning and grain refinement effects of specific intermediate phases, and the nanoscale precipitates generated within the matrix under the high cooling conditions of liquid forging, a high yield strength is achieved. Simultaneously, the addition of Mn and Cr elements allows the β-AlFeSi phase formed by high Fe content to transform into the α-Al(Fe,Mn,Cr)Si phase, thereby changing its morphology and reducing its cutting effect on the matrix. Ga element can also modify the eutectic Si, transforming the needle-like eutectic Si into fine fibrous Si, further weakening its cutting effect on the matrix alloy. Thus, by improving the morphology of harmful impurity phases and optimizing the eutectic microstructure, the cutting effect of phase structure on the matrix in traditional materials is eliminated, significantly enhancing the alloy's plasticity and achieving a synergistic match between strength and plasticity. Furthermore, the material is compatible with the recycling of waste materials, eliminating the need for strict control of impurity content, effectively reducing raw material costs, and balancing economic efficiency and environmental friendliness. It fully meets the requirements of the automotive and other fields for lightweight, high-strength, and reliable components. Therefore, it can be seen that the liquid forging aluminum alloy of this invention effectively solves the problems of difficulty in balancing formability and mechanical properties and poor cost control in existing materials, possessing significant comprehensive advantages. Attached Figure Description

[0018] Figure 1 This is a 500x metallographic diagram of the liquid forging workpiece provided by the present invention; Figure 2 This is a 1000x metallographic diagram of the liquid forging workpiece provided by the present invention; Figure 3 The stress-strain curve of the liquid forging workpiece provided by the present invention. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. The described embodiments are some, but not all, of the embodiments of the present invention.

[0020] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0021] This invention provides an aluminum alloy for liquid forging, comprising, by mass percentage: Si: 6.0%–10.0%, Mg: 0.3%–1.0%, Mn: 0.05%–0.8%, Cr: 0.05%–0.6%, Ga: 0.005%–0.05%, Hf: 0.01%–0.2%, W: 0.01%–0.2%, Y: 0.03%–0.4%, Nd: 0.03%–0.4%, Er: 0.03%–0.4%; wherein Fe ≤ 1.0%, the total amount of Hf and W ≤ 0.25%, the total amount of Y, Nd, and Er ranges from 0.2% to 0.8%, other unavoidable single impurity elements ≤ 0.03%, the total amount of impurity elements ≤ 0.15%, and the balance is aluminum.

[0022] The specific content of each element is determined based on actual production needs and is not limited here.

[0023] Further, an aluminum alloy for liquid forging comprises, by mass percentage: Si: 6.5%–8.5%, Mg: 0.4%–0.8%, Mn: 0.1%–0.6%, Cr: 0.08%–0.4%, Ga: 0.008%–0.04%, Hf: 0.03%–0.18%, W: 0.03%–0.18%, Y: 0.05%–0.3%, Nd: 0.05%–0.3%, Er: 0.05%–0.3%, wherein Fe ≤ 0.8%, the total amount of Hf and W ≤ 0.25%, the total amount of Y, Nd, and Er ranges from 0.2% to 0.8%, other unavoidable single impurity elements ≤ 0.03%, the total amount of impurity elements ≤ 0.15%, and the balance is aluminum.

[0024] The rule that no additional Fe element is added during the alloy preparation process, and that its content is specified, is to accommodate the production method that uses scrap aluminum as raw material.

[0025] It is worth noting that the roles of various chemical elements in this invention are mainly divided into three categories. The first category consists of main alloying elements, including Si and Mg; the second category consists of elements that mainly play a modifying role, including Mn, Cr, Sr, and Ga; and the third category consists of microalloying elements, which are divided into two types: Hf and W, and Y, Nd, and Er rare earth elements. The specific roles of each element are as follows: Main alloying element: Si is the main alloying element. The hypoeutectic alloy of the Al-Si system has good fluidity and low thermal shrinkage in the liquid state, which can fill the casting mold well and has excellent casting filling performance. The role of Mg is mainly to form a metastable β” phase with Si during artificial aging, which precipitates out from the supersaturated solid solution and becomes the main strengthening phase. In addition, Fe is not added in this invention. Its high content range is mainly to make it possible to use recycled aluminum: on the one hand, recycled aluminum will more or less bring in some iron parts, resulting in an increase in Fe content; on the other hand, Fe will gradually accumulate during repeated remelting of aluminum alloy, and its content will gradually increase with the volatilization of the base element Al.

[0026] The modifying elements, Mn and Cr, primarily function to modify the iron-rich phase. Without Mn and Cr, the high Fe content in aluminum alloys leads to the formation of needle-like β-AlFeSi phases during casting, which can fracture the alloy matrix and reduce its mechanical properties. This invention adjusts the Mn and Cr content to transform the β-AlFeSi phase into the α-Al(Fe,Mn,Cr)Si phase, changing its morphology from needle-like to short rod-like, thus reducing the fracture effect on the matrix. Ga modifies the eutectic Si, transforming the needle-like eutectic Si into fine fibrous structures, thereby weakening its fracture effect on the matrix alloy.

[0027] Microalloying elements: Hf and W are high-melting-point metallic elements. Their main function is to form a certain intermediate phase in aluminum alloys. The phase is small in size, uniformly distributed, and mostly distributed along the grain boundaries, which plays a role in "pinning" the grain boundaries, thereby improving the strength of aluminum alloy materials. Y, Nd, and Er are rare earth elements, playing two main roles: First, in aluminum alloys, Y, Nd, and Er can form intermediate phases such as Al3Y, Al3Nd, and Al3Er. These intermediate phases have a face-centered cubic crystal structure similar to α-Al, with similar lattice constants, indicating low mismatch. This provides high-quality heterogeneous nucleation sites for α-Al grains, promoting their formation and macroscopically refining the grain size. Second, under the high cooling rate provided by liquid forging, Y, Nd, and Er can become supersaturated within the matrix grains. During subsequent heat treatment, these supersaturated elements slowly precipitate from the matrix, forming nanoscale precipitates that hinder dislocation slip, effectively "pinning" dislocations and thus improving the mechanical properties of the alloy.

[0028] Therefore, it can be seen that the liquid forging aluminum alloy prepared by the formula of the present invention has the advantages of excellent comprehensive performance, excellent process performance, and low tendency to hot cracking. It is suitable for the production of aluminum alloy castings with various complex shapes and drastic changes in wall thickness, and can provide a practical solution for lightweighting in the traditional automobile industry and the new energy vehicle industry.

[0029] This invention provides a method for preparing aluminum alloys for liquid forging, comprising the following steps: S110, Weigh the raw materials according to the formula.

[0030] Specifically, the raw materials aluminum ingots, scrap aluminum, industrial silicon, magnesium ingots, aluminum-manganese master alloys, aluminum-chromium master alloys, aluminum-gallium master alloys, aluminum-hafnium master alloys, aluminum-tungsten master alloys, aluminum-yttrium master alloys, aluminum-neodymium master alloys, and aluminum-erbium master alloys are weighed according to their main components.

[0031] S120 involves refining the raw materials multiple times, with stirring during the process, until the content of all elements reaches the required level in the formula, resulting in a refined melt.

[0032] The specific steps can be as follows: (1) First, aluminum ingots, scrap aluminum, industrial silicon, aluminum-manganese master alloy, aluminum-chromium master alloy, aluminum-hafnium master alloy, aluminum-tungsten master alloy, aluminum-yttrium master alloy, aluminum-neodymium master alloy, and aluminum-erbium master alloy are loaded into a melting and holding furnace and heated to melt. The furnace is then held at a set temperature of 720℃~860℃. During the holding period, mechanical stirring is applied to the melt to make the alloy elements uniform. (2) Then, the first refining process is carried out. The first refining is carried out by injecting high-purity argon gas to blow remelting refining agent. The amount of remelting refining agent is 0.1% to 0.5% of the total amount of material in the furnace. The refining time is 20 min to 40 min, such as 20 min, 30 min or 40 min. The refining temperature is 720℃ to 860℃. After completion, the slag is removed after standing for a period of time. (3) Then add magnesium ingots and aluminum-gallium master alloy and heat and melt at a temperature of 700℃~800℃. During this period, mechanical stirring is applied to the melt. Then take a small amount of sample from the high temperature melt for chemical composition analysis. If there is a deviation in composition, adjust the composition and take samples again for analysis until all elements reach the expected index. (4) Then a second refining process is carried out. The second refining is carried out by injecting high-purity argon gas to purge the remelting agent. The amount of remelting agent is 0.1% to 0.3% of the total amount of material in the furnace. The refining time is 10 min to 30 min, such as 10 min, 20 min or 30 min. The refining temperature is 700℃ to 800℃. After the process is completed, the slag is removed after standing for a period of time. After the refining is completed, the sample is taken again for analysis. If the composition is still within the expected index range, no further processing is required. If the composition deviates, the composition is adjusted until all elements reach the expected composition range. Only then can the refined melt be obtained and proceed to the next process.

[0033] Furthermore, the total time for the two refining processes is 30 to 60 minutes.

[0034] S130 involves casting refined melt after undergoing a two-stage filtration process to obtain liquid forging aluminum alloy ingots.

[0035] Specifically, after the refined melt undergoes a two-stage filtration process, it is released from the bottom of the furnace and enters an automatic ingot casting machine for casting, resulting in a liquid forging aluminum alloy ingot.

[0036] The first stage of the dual-stage filtration process uses a 60-mesh filter plate, while the second stage uses an 80-mesh filter plate.

[0037] The casting temperature of aluminum alloy melt is 640℃~740℃.

[0038] This invention provides the application of the above-mentioned aluminum alloy for liquid forging in liquid forging, and provides a method for manufacturing liquid forged workpieces, including the following steps: S210, the liquid forging aluminum alloy is heated and remelted and stirred to obtain a remelted melt. The liquid forging aluminum alloy is prepared by the above-mentioned preparation method of liquid forging aluminum alloy.

[0039] Specifically, the prepared liquid aluminum alloy ingot for forging is placed in an aluminum melting furnace, heated, remelted, and stirred. The remelting holding temperature is 650℃~780℃, and an aluminum strontium intermediate is added to ensure that the Sr element addition amount is 0.01%~0.25% by mass. Further, the Sr element addition amount can be 0.01%~0.2%, specifically 0.01%, 0.11%, or 0.2% by mass. After stirring evenly, a remelted melt is obtained. Sr element can modify eutectic Si, having the same effect as Ga element.

[0040] S220 is used to refine the remelted melt. After standing, the slag is removed and the melt is kept warm to obtain a refined melt.

[0041] Specifically, the remelted melt is refined using a high-purity argon gas injection method with a remelting refining agent. The amount of the remelting refining agent is 0.1% to 0.3% of the total material in the furnace. The refining time is set to 10 to 30 minutes, and the refining temperature is 650℃ to 780℃. After settling, the slag is removed, and the melt is kept at a certain temperature range.

[0042] S230 involves liquid forging a refined melt, removing it, and cooling it to obtain a workpiece prepared by liquid forging.

[0043] Specifically, a robotic arm is used to transfer the refined melt to a liquid forging machine for liquid forging, and the workpiece is obtained after cooling.

[0044] The temperature of the molten aluminum in liquid forging is 650℃~720℃, the temperature of the die is 200℃~300℃, the specific pressure is 50MPa~200MPa, the filling speed of the molten aluminum is 0.01m / s~0.50m / s, and the holding time is 8s~40s.

[0045] S240 involves treating the workpiece prepared by liquid forging with solution treatment and artificial aging treatment. After the treatment, the workpiece is removed and cooled to room temperature by strong air cooling to obtain the liquid forged workpiece.

[0046] The specific steps are as follows: (1) The workpiece prepared by liquid forging is subjected to solution treatment, that is, the workpiece is placed in a heating furnace and heated and kept at a certain temperature for a certain time, and then the workpiece is taken out and water-cooled quenched.

[0047] The working parameters for solution treatment include: heating rate of 1℃ / min to 10℃ / min, holding temperature of 500℃ to 600℃, holding time of 1h to 8h, cooling method of water cooling, and cooling water temperature of 40℃ to 80℃. (2) The workpiece after solution treatment is subjected to artificial aging treatment. The working parameters of artificial aging treatment include: heating rate of 1℃ / min to 10℃ / min, holding temperature of 120℃ to 200℃, and holding time of 2h to 14h. After the treatment, the workpiece is taken out and cooled to room temperature by strong air cooling.

[0048] It is worth noting that the aluminum alloy material involved in this invention, after being liquid forged and subsequently heat-treated, possesses both high strength and plasticity, exhibiting excellent comprehensive mechanical properties and enabling weight reduction of parts.

[0049] Example 1 An aluminum alloy for liquid forging comprises, by mass percentage: Si: 7.8%, Mg: 0.56%, Fe: 0.65%, Mn: 0.60%, Cr: 0.23%, Ga: 0.016%, Hf: 0.11%, W: 0.12%, Y: 0.11%, Nd: 0.27%, Er: 0.19%, other unavoidable single impurity elements ≤0.03%, total impurity elements ≤0.15%, and the balance being aluminum.

[0050] A method for preparing an aluminum alloy for liquid forging includes the following steps: Weigh the raw materials according to the above components; First, aluminum ingots, scrap aluminum, industrial silicon, aluminum-manganese master alloy, aluminum-chromium master alloy, aluminum-hafnium master alloy, aluminum-tungsten master alloy, aluminum-yttrium master alloy, aluminum-neodymium master alloy, and aluminum-erbium master alloy are loaded into a melting and holding furnace and heated to 820°C. The furnace is then held at this temperature, and mechanical stirring is applied during the process to ensure uniform composition. When the temperature reaches 780℃, refining is carried out by argon gas injection of remelting refining agent. The amount of refining agent is 0.2% of the total material weight, the duration is 40 minutes, and the slag is removed after standing for 30 minutes. Magnesium ingots and aluminum-gallium master alloy were added at 760°C, and mechanical stirring was applied during the process to ensure uniform composition. Subsequently, samples were taken to analyze the chemical composition. After the composition meets the requirements, a second refining process is carried out at a temperature of 760℃ using an argon-injected remelting agent. The amount of refining agent used is 0.2% of the total material weight, and the process lasts for 20 minutes. After standing for 30 minutes, the slag is removed. After refining, samples are taken again for analysis. If the composition is still within the expected range, no further action is required. If there is a deviation in the composition, the composition is adjusted until all elements reach the expected range, thus obtaining the refined melt. When the temperature of the refined melt drops to 720°C, the molten aluminum is released for casting. After passing through a double-stage filtration process of 60 mesh and 80 mesh, it is poured into an aluminum ingot mold in sequence. After cooling, a liquid forging aluminum alloy ingot is obtained.

[0051] A method for manufacturing a liquid forged workpiece includes the following steps: The prepared liquid aluminum alloy ingot for forging is placed in an aluminum melting furnace, heated and remelted, and held at 730°C. During this period, mechanical stirring is applied to make the composition uniform. Then, an aluminum-strontium master alloy is added so that the amount of Sr added is 0.04% by mass, and the remelted melt is obtained. The remelted melt was refined for 20 minutes under a holding temperature of 720℃. High-purity argon gas was used to inject a remelting refining agent. The amount of refining agent was 0.15% of the total amount of material in the furnace. After standing, the slag was removed to obtain the refined melt. The refined melt is then transferred to a liquid forging machine using a robotic arm for liquid forging. After cooling, the workpiece prepared by liquid forging is obtained. The temperature of the aluminum melt is maintained at 680℃~700℃, the mold temperature is controlled at 230℃~250℃, the specific pressure is set to 100MPa, the aluminum melt filling speed is 0.25m / s, and the holding time is 25 seconds. The workpiece prepared by liquid forging is placed in a quenching furnace and heated to 540°C at a heating rate of 3°C / min and held at that temperature for 3 hours. After the holding time is completed, the workpiece is taken out and immersed in water at 60°C~70°C for cooling and quenching, which is to perform solution treatment. The solution-treated workpiece is then subjected to artificial aging treatment: it is placed in an annealing furnace and heated to 155°C at a heating rate of 3°C / minute, and held at this temperature for 5 hours. After the holding period, the workpiece is taken out and cooled to room temperature by strong air cooling to obtain the liquid forged workpiece.

[0052] Example 2 An aluminum alloy for liquid forging comprises, by mass percentage: Si: 8.0%, Mg: 0.59%, Fe: 0.62%, Mn: 0.48%, Cr: 0.22%, Ga: 0.02%, Hf: 0.10%, W: 0.09%, Y: 0.25%, Nd: 0.11%, Er: 0.16%, other unavoidable single impurity elements ≤0.03%, total impurity elements ≤0.15%, and the balance being aluminum.

[0053] A method for preparing an aluminum alloy for liquid forging includes the following steps: Weigh the raw materials according to the above components; First, aluminum ingots, scrap aluminum, industrial silicon, aluminum-manganese master alloy, aluminum-chromium master alloy, aluminum-hafnium master alloy, aluminum-tungsten master alloy, aluminum-yttrium master alloy, aluminum-neodymium master alloy, and aluminum-erbium master alloy are loaded into a melting and holding furnace and heated to 840°C. The furnace is then held at this temperature, and mechanical stirring is applied during the process to ensure uniform composition. When the temperature reaches 770℃, refining is carried out by argon gas injection of remelting refining agent. The amount of refining agent is 0.25% of the total material weight, the duration is 40 minutes, and the slag is removed after standing for 30 minutes. Magnesium ingots and aluminum-gallium master alloy were added at 750°C, and mechanical stirring was applied during the process to make the composition uniform. Then, samples were taken to test the chemical composition. After the composition meets the requirements, a second refining process is carried out at a temperature of 750℃ using an argon-injected remelting agent. The amount of refining agent used is 0.25% of the total material weight, and the process lasts for 20 minutes. After standing for 30 minutes, the slag is removed. After refining, samples are taken again for analysis. If the composition is still within the expected range, no further action is required. If there is a deviation in the composition, the composition is adjusted until all elements reach the expected range, thus obtaining the refined melt. When the temperature of the refined melt drops to 710℃, the molten aluminum is released for casting. After passing through a double-stage filtration process of 60 mesh and 80 mesh, it is poured into an aluminum ingot mold in sequence. After cooling, a liquid aluminum alloy ingot for die forging is obtained.

[0054] A method for manufacturing a liquid forged workpiece includes the following steps: The prepared liquid aluminum alloy ingot for forging is placed in an aluminum melting furnace, heated and remelted, and held at 720°C. During this period, mechanical stirring is applied to make the composition uniform. Then, an aluminum-strontium master alloy is added so that the amount of Sr added is 0.04% by mass, and the remelted melt is obtained. The remelted melt was refined for 20 minutes under a holding temperature of 720℃. High-purity argon gas was used to inject a remelting refining agent. The amount of refining agent was 0.2% of the total amount of material in the furnace. After standing, the slag was removed to obtain the refined melt. The refined melt is then transferred to a liquid forging machine using a robotic arm for liquid forging. After cooling, the workpiece prepared by liquid forging is obtained. The temperature of the aluminum melt is maintained at 660℃~680℃, the mold temperature is controlled at 230℃~250℃, the specific pressure is set at 120MPa, the aluminum melt filling speed is 0.15m / s, and the holding time is 20 seconds. The workpiece prepared by liquid forging is placed in a quenching furnace and heated to 530°C at a heating rate of 5°C / min and held at this temperature for 3.5 hours. After the holding time is completed, the workpiece is taken out and immersed in water at 60°C~70°C for cooling and quenching, which is to perform solution treatment. The solution-treated workpiece is then subjected to artificial aging treatment: it is placed in an annealing furnace and heated to 175°C at a heating rate of 5°C / minute, and held at this temperature for 4 hours. After the holding period, the workpiece is taken out and cooled to room temperature by strong air cooling to obtain the liquid forged workpiece.

[0055] Example 3 An aluminum alloy for liquid forging comprises, by mass percentage: Si: 8.4%, Mg: 0.62%, Fe: 0.73%, Mn: 0.57%, Cr: 0.13%, Ga: 0.01%, Hf: 0.08%, W: 0.08%, Y: 0.10%, Nd: 0.25%, Er: 0.25%, other unavoidable single impurity elements ≤0.03%, total impurity elements ≤0.15%, and the balance being aluminum.

[0056] A method for preparing an aluminum alloy for liquid forging includes the following steps: Weigh the raw materials according to the above components; First, aluminum ingots, scrap aluminum, industrial silicon, aluminum-manganese master alloy, aluminum-chromium master alloy, aluminum-hafnium master alloy, aluminum-tungsten master alloy, aluminum-yttrium master alloy, aluminum-neodymium master alloy, and aluminum-erbium master alloy are loaded into a melting and holding furnace and heated to 850°C. The furnace is then held at this temperature, and mechanical stirring is applied during the process to ensure uniform composition. When the temperature reaches 760℃, refining is carried out by argon gas injection of remelting refining agent. The amount of refining agent is 0.25% of the total material weight, the duration is 40 minutes, and the slag is removed after standing for 30 minutes. Magnesium ingots and aluminum-gallium master alloy were added at 740°C, and mechanical stirring was applied during the process to ensure uniform composition. Subsequently, samples were taken to analyze the chemical composition. After the composition meets the requirements, a second refining process is carried out at a temperature of 740℃ using an argon-injected remelting agent. The amount of refining agent used is 0.25% of the total material weight, and the process lasts for 20 minutes. After standing for 30 minutes, the slag is removed. After refining, samples are taken again for analysis. If the composition is still within the expected range, no further action is required. If there is a deviation in the composition, the composition is adjusted until all elements reach the expected range, thus obtaining the refined melt. When the temperature of the refined melt drops to 720°C, the molten aluminum is released for casting. After passing through a double-stage filtration process of 60 mesh and 80 mesh, it is poured into an aluminum ingot mold in sequence. After cooling, a liquid forging aluminum alloy ingot is obtained.

[0057] A method for manufacturing a liquid forged workpiece includes the following steps: The prepared liquid aluminum alloy ingot for forging is placed in an aluminum melting furnace, heated and remelted, and held at 730°C. During this period, mechanical stirring is applied to make the composition uniform. Then, an aluminum-strontium master alloy is added so that the amount of Sr added is 0.04% by mass, and the remelted melt is obtained. The melt was remelted and refined for 20 minutes under a holding temperature of 730℃. High-purity argon gas was used to inject a remelting refining agent, with the amount of refining agent being 0.15% of the total amount of material in the furnace. After standing, the slag was removed to obtain the refined melt. The refined melt is then transferred to a liquid forging machine using a robotic arm for liquid forging. After cooling, the workpiece prepared by liquid forging is obtained. The temperature of the aluminum melt is maintained at 690℃~710℃, the mold temperature is controlled at 230℃~250℃, the specific pressure is set at 150MPa, the aluminum melt filling speed is 0.10m / s, and the holding time is 20 seconds. The workpiece prepared by liquid forging is placed in a quenching furnace and heated to 550°C at a heating rate of 2°C / min and held at that temperature for 4 hours. After the holding time is completed, the workpiece is taken out and immersed in water at 60°C~70°C for cooling and quenching, which is to perform solution treatment. The solution-treated workpiece is then subjected to artificial aging treatment: it is placed in an annealing furnace and heated to 195°C at a heating rate of 2°C / minute, and held at this temperature for 4 hours. After the holding period, the workpiece is taken out and cooled to room temperature by strong air cooling to obtain the liquid forged workpiece.

[0058] Comparative Example 1 Comparatively, liquid forged parts produced using A356 aluminum alloy are used. A356 aluminum alloy, by mass percentage, includes: Si: 6.9%, Mg: 0.32%, Ti: 0.02%, Sr: 0.02%, Fe: 0.13%, other unavoidable single impurity elements ≤0.03%, total impurity elements ≤0.15%, and the balance is aluminum.

[0059] The liquid forging temperature of A356 aluminum alloy is 660℃, the die temperature is 230℃, the specific pressure is 130MPa, the aluminum liquid filling speed is 0.18m / s, and the holding time is 15 seconds. The solution treatment temperature is 530℃, the holding time is 2.5 hours, and the cooling method is water quenching at 70℃. The artificial aging temperature is 160℃, and the holding time is 3.5 hours.

[0060] Comparative Example 2 Comparison was made with liquid forging workpieces produced using ADC12 aluminum alloy. ADC12 aluminum alloy, by mass percentage, includes: Si: 10.5%, Mg: 0.19%, Cu: 1.5%, Mn: 0.46%, Zn: 0.18%, Ti: 0.03%, Fe: 0.87%, other unavoidable single impurity elements ≤0.03%, total impurity elements ≤0.15%, and the balance being aluminum.

[0061] The temperature for liquid forging of ADC12 aluminum alloy is 70℃, the mold temperature is 230℃, the specific pressure is 140MPa, the aluminum liquid filling speed is 0.15m / s, and the holding time is 16 seconds. The solution treatment temperature is 540℃, the holding time is 3 hours, and the cooling method is water quenching at 70℃. The artificial aging temperature is 170℃, and the holding time is 4 hours.

[0062] Performance testing The liquid forged workpieces prepared in Examples 1 to 3 and the liquid forged workpieces prepared in Comparative Examples 1 and 2 were tested as follows: 1. Mechanical property testing According to GB / T 228.1-2010 "Metallic materials, tensile testing - Part 1: Test at room temperature", samples of the liquid forged workpieces prepared in Examples 1 to 3 and Comparative Examples 1 and 2 were taken for mechanical property testing to examine their yield strength, tensile strength, and elongation after fracture. The results are shown in Table 1.

[0063] Table 1 Mechanical performance test results As can be seen from Table 1, the liquid forged workpieces prepared in Examples 1 to 3 of the present invention have significantly better yield strength, tensile strength and Brinell hardness than Comparative Example 1 (A356 aluminum alloy) and Comparative Example 2 (ADC12 aluminum alloy); the elongation after fracture is comparable to that of A356 aluminum alloy and significantly improved compared with ADC12 aluminum alloy. Overall, they exhibit comprehensive mechanical property advantages of "high strength, high hardness and excellent plasticity", which meets the requirements of automotive parts for the combination of strength and plasticity.

[0064] The core beneficial effects of this invention can be further verified by referring to the accompanying drawings: refer to Figure 1 (500x metallographic view of the liquid forged workpiece of this invention) and Figure 2 (1000x metallographic analysis of the liquid forged workpiece of this invention) The liquid forged workpiece of this invention exhibits fine and uniform grains, a dense overall structure, and no obvious casting defects such as porosity or looseness. Simultaneously, the second phase is distributed in the matrix in a fine and dispersed form, without the needle-like or flaky harmful phases commonly found in traditional aluminum alloys. This microstructure benefits from the synergistic effect of composition optimization and the liquid forging process, effectively reducing the probability of forming defects such as hot cracking, ensuring the forming qualification rate of complex-shaped parts, and avoiding the cutting of the matrix by harmful phases, thus laying the foundation for the synergistic improvement of strength and plasticity.

[0065] refer to Figure 3 The stress-strain curves intuitively reflect the mechanical properties of the material: the curves have a clear yield stage and a reasonable plastic deformation extension section, indicating that the material has both high yield / tensile strength (significantly increased peak stress) and good plastic deformation capacity (no brittle fracture drop after the peak). Therefore, it can be seen that the present invention has successfully solved the contradiction of "strength increase leads to a sharp drop in plasticity" in traditional aluminum alloys, and can meet the service reliability requirements of automotive parts under alternating loads.

[0066] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0067] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this invention is in use. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention. In addition, the terms "first," "second," "third," etc., are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0068] Furthermore, terms such as "horizontal," "vertical," and "sag" do not imply that components must be absolutely horizontal or suspended, but rather that they can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," not that the structure must be completely horizontal, but can be slightly tilted.

[0069] In this invention, unless otherwise expressly specified and limited, "above or below" a first feature may include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on" the first feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the first feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0070] Although the description of the invention has been given in conjunction with the specific embodiments described above, it will be apparent to those skilled in the art that many substitutions, modifications, and variations can be made based on the foregoing. Therefore, all such substitutions, modifications, and variations are included within the spirit and scope of the appended claims.

Claims

1. An aluminum alloy for liquid die forging, characterized by comprising, in mass %, The composition by mass percentage includes: Si: 6.0%–10.0%, Mg: 0.3%–1.0%, Mn: 0.05%–0.8%, Cr: 0.05%–0.6%, Ga: 0.005%–0.05%, Hf: 0.01%–0.2%, W: 0.01%–0.2%, Y: 0.03%–0.4%, Nd: 0.03%–0.4%, Er: 0.03%–0.4%. The composition is as follows: Fe ≤ 1.0%, total Hf and W ≤ 0.25%, total Y, Nd and Er range from 0.2% to 0.8%, other unavoidable single impurity elements ≤ 0.03%, total impurity elements ≤ 0.15%, and the balance is aluminum.

2. The aluminum alloy for liquid forging according to claim 1, characterized in that, In terms of mass percentage Including: Si: 6.5% ~ 8.5%, Mg: 0.4% ~ 0.8%, Mn: 0.1% ~ 0.6%, Cr: 0.08% ~ 0.4%, Ga: 0.008% ~ 0.04% , Hf: 0.03% ~ 0.18%, W: 0.03% ~ 0.18%, Y: 0.05% ~ 0.3%, Nd: 0.05% ~ 0.3%, Er: 0.05% ~ 0.3%, Among them, Fe≤0.8%, the total amount of Hf and W elements≤0.25%, the total amount of Y, Nd and Er elements ranges from 0.2% to 0.8%, other unavoidable single impurity elements≤0.03%, the total amount of impurity elements≤0.15%, and the balance is aluminum.

3. The aluminum alloy for liquid forging according to claim 2, characterized in that, The Fe element content is ≤0.8%, of which the Fe introduced from the raw materials does not exceed 0.8%, and the additional Fe added is 0.

4. A method for preparing an aluminum alloy for liquid forging, characterized in that, include: Weigh the raw materials according to the formula; The raw materials are refined multiple times, with stirring during the process, until the content of all elements reaches the content required by the formula, to obtain a refined melt. The refined melt is subjected to a two-stage filtration process and then cast to obtain the liquid forging aluminum alloy ingot.

5. The method for preparing aluminum alloy for liquid forging according to claim 4, characterized in that, The working parameters for the multiple refining processes include: The first refining process uses high-purity argon gas to inject a remelting refining agent. The amount of the remelting refining agent is 0.1% to 0.5% of the total amount of material in the furnace. The refining time is 20 min to 40 min, and the refining temperature is 720℃ to 860℃. The second refining process uses high-purity argon gas to inject a remelting refining agent. The amount of the remelting refining agent is 0.1% to 0.3% of the total amount of material in the furnace. The refining time is 10 min to 30 min, and the refining temperature is 700℃ to 800℃.

6. A method for manufacturing a liquid forged workpiece, characterized in that, include: The liquid forging aluminum alloy is heated, remelted, and stirred to obtain a remelted melt, wherein the liquid forging aluminum alloy is prepared by the preparation method of the liquid forging aluminum alloy according to any one of claims 4 to 5; The remelted melt is refined, allowed to stand, slag is removed, and the melt is kept warm to obtain a refined melt. The refined melt is liquid-forged into shape, and after being removed and cooled, a workpiece prepared by liquid forging is obtained. The workpiece prepared by liquid forging is subjected to solution treatment and artificial aging treatment. After the treatment, it is taken out and cooled to room temperature by strong air cooling to obtain the liquid forged workpiece.

7. The method for manufacturing a liquid forged workpiece according to claim 6, characterized in that, The working parameters for the liquid forging process include: The temperature of the molten aluminum is 650℃~720℃, the temperature of the mold is 200℃~300℃, the specific pressure is 50MPa~200MPa, the filling speed of the molten aluminum is 0.01m / s~0.50m / s, and the holding time is 8s~40s.

8. The method for manufacturing a liquid forged workpiece according to claim 6, characterized in that, The operating parameters for the solution treatment include: The heating rate is 1℃ / min to 10℃ / min, the holding temperature is 500℃ to 600℃, the holding time is 1h to 8h, the cooling method is water cooling, and the cooling water temperature is 40℃ to 80℃.

9. The method for manufacturing a liquid forged workpiece according to claim 6, characterized in that, The working parameters for the artificial aging process include: The heating rate is 1℃ / min to 10℃ / min, the holding temperature is 120℃ to 200℃, and the holding time is 2h to 14h.

10. The application of the aluminum alloy for liquid forging as described in claims 1 to 3 in liquid forging.

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