Al-si-cu-fe aluminum alloy with high fe content and a method of manufacturing the same

Abstract

The application provides an Al-Si-Cu-Fe aluminum alloy with high Fe content and a preparation method thereof, and belongs to the technical field of aluminum alloy materials. The Al-Si-Cu-Fe aluminum alloy is composed of the following components in percentage by mass: Si: 7-10%; Cu: 0.2-1.3%; Fe: 0.2-1.0%; Mg: 0.15-0.4%; Mn: 0.2-1.0%; Cr: 0.1-0.5%; Ni: 0.03-0.15%; Nb: 0.03-0.15%; RE: 0.05-0.2%; Ti: 0.08-0.2%; Sr: 0.008-0.02%; and the rest is aluminum. The application controls the molar ratio of key elements, improves the solubility of Fe in the aluminum alloy matrix, makes most of the Fe to be dissolved or form fine nanoparticles, reduces harmful Fe-rich phases, thereby improves the upper limit of the Fe content while ensuring the performance, reduces the cost and carbon emission of the product.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of aluminum alloy material preparation, in particular to an Al-Si-Cu-Fe aluminum alloy with high Fe content and a preparation method thereof. BACKGROUND

[0002] Using a high proportion of recycled aluminum can significantly reduce the cost and carbon emissions of aluminum alloy parts. Aluminum alloy wheels are important load-bearing parts of automobiles and motorcycles, and their mechanical properties and reliability not only affect the comfort and stability during driving, but also are related to the safety of the vehicle itself. There are three main forming methods for wheels, namely gravity casting, low-pressure casting and forging. The cost of forged wheels is relatively high, and their large-scale use is limited, mainly used in heavy-duty wheels and high-end vehicles. Gravity casting accounts for more than 90% of motorcycle wheel production due to its lower production cost, but the production efficiency is low, while automobile wheels are mostly produced by low-pressure casting. A356 aluminum alloy is used for wheel casting. In order to ensure the strength and toughness of the wheel, it needs to be treated by T6 solid solution and aging, and the Fe content in A356 aluminum alloy needs to be controlled within 0.2%. This is mainly due to the fact that the Fe-rich phase in A356 alloy is in the form of needles, and a large number of needle-shaped Fe phases can easily break the matrix, reducing the elongation A of the castings, causing impact and fatigue fracture of the wheel.

[0003] It is well known that the Fe content in recycled aluminum is generally high. For example, the Fe content in recycled cans exceeds 0.8% due to the mixing of iron cans and iron parts contained in the cans themselves. After removing Fe by magnetic separation, the Fe content is still more than 0.4%. The Fe content in industrial scrap materials purchased on the market is generally more than 0.25%, even more than 0.35%. The Fe content in primary aluminum, especially in die-cast aluminum alloy, is even higher, for example, the Fe content in ADC12 aluminum alloy housing is 0.9% to 1.3%. Generally speaking, as the Fe content increases, the elongation A of the aluminum alloy decreases. For example, the elongation A of ADC12 aluminum alloy with 1.0% Fe is only 1% to 3%. This limits the application of recycled aluminum in load-bearing parts such as automobile wheels with elongation A ≥ 7% and motorcycle wheels with elongation A ≥ 4%. In order to control the Fe content, A356 aluminum alloy and the publicly disclosed heat-treatment-free aluminum alloy can only be prepared using 100% pure aluminum ingots or primary aluminum, or prepared by adding primary aluminum such as industrial profiles, white materials and aluminum wires with low Fe content and high cost. It is impossible to add a large amount of primary aluminum such as ADC12 housing and other die-cast parts with higher Fe content and lower cost. In order to meet the needs of future industry development, the materials and forming methods of load-bearing parts such as wheels need to be reformed.

[0004] Due to the advantages of high efficiency, high dimensional accuracy, excellent mechanical properties, and suitability for mass production, die casting has become a trend in the production of load-bearing components for automobiles and motorcycles, such as wheels. However, the aluminum alloy materials currently used in die casting, such as ADC12 or heat-free aluminum alloys with Fe content not exceeding 0.2%, produce parts with low strength or toughness and high cost, which limits the development of die-cast aluminum alloy wheels. Chinese patent CN115233046A discloses a non-heat-treated Al-Si-Mg-Fe aluminum alloy based on recycled aluminum with high iron content and its preparation method. It proposes to strictly control the ratio of La, Ce, Zr, and Cr elements, refine and spheroidize the Fe-rich phase in the aluminum-silicon alloy, and refine the blocky Fe-rich phase Al(FeMnCr)Si with a diameter between 2μm and 10μm into fine granular Al(FeMnCr)Cu phase. Its technical features lie in the precise control of the ratio of La, Ce, Ti, Zr elements to Fe, Mn, and Cr elements. This ratio, combined with the shearing effect of electromagnetic stirring, promotes the transformation of the acicular and blocky Fe-rich phases in the aluminum-silicon alloy, which affect the elongation after fracture (A), into fine-grained granular phases. The Al-Si-Mg-Fe aluminum alloy provided by this invention uses recycled aluminum as the melt, expanding the application range of recycled aluminum, increasing the upper limit of Fe content in high-strength and tough aluminum alloy materials, and significantly improving the strength and toughness of the product.

[0005] However, there are still problems such as insufficient performance of die-cast wheels, high manufacturing costs, and environmental unfriendliness. At the same time, it has not been able to further break through the upper limit of Fe content in load-bearing components such as automobile and motorcycle wheels. Summary of the Invention

[0006] One object of the present invention is to provide a high-strength, high-toughness, heat-free Al-Si-Cu-Fe aluminum alloy with high Fe content.

[0007] Al-Si-Cu-Fe aluminum alloy is composed of the following components by mass percentage: Si: 7%–10%; Cu: 0.2%–1.3%; Fe: 0.2%–1.0%; Mg: 0.15%–0.4%; Mn: 0.2%–1.0%; Cr: 0.1%–0.5%; Ni: 0.03%–0.15%; Nb: 0.03%–0.15%; RE: 0.05%–0.2%; Ti: 0.08%–0.2%; Sr: 0.008%–0.02%; the remainder is aluminum.

[0008] Furthermore, the aluminum component raw materials are derived from recycled aluminum and other aluminum materials. The recycled aluminum includes one or more combinations of waste engine casings, beverage cans, profiles, aluminum wire, or scrapped automotive aluminum. The mass of the recycled aluminum accounts for 30% to 100% of the Al-Si-Cu-Fe aluminum alloy mass. The recycled aluminum includes ADC12 and other waste engine casings, beverage cans, profiles, aluminum wire, or scrapped automotive aluminum. The Fe content in the recycled aluminum is 0.25% to 1.3% by mass, with the Fe content of ADC12 waste engine casings and other raw aluminum being 0.9% to 1.3%; the Fe content of magnetically separated beverage cans being 0.4% to 0.5%; and the Fe content of other profiles being 0.25% to 0.4%. The recycled aluminum is mainly composed of ADC12 waste engine casings and other raw aluminum, mixed with a certain amount of refined aluminum such as beverage cans and scrap profiles, and pure aluminum ingots or primary aluminum. When the Fe content increases from 0.6% to 1.0%, the proportion of raw aluminum can be increased from below 40% to above 55%; while the proportion of aluminum ingots can be reduced from above 36% to 0%. This not only expands the sources and proportions of recycled aluminum, but also reduces costs and carbon emissions.

[0009] Furthermore, the Fe mass percentage is 0.5% to 0.8%, and the mass of recycled aluminum accounts for 70% to 90% of the mass of the Al-Si-Cu-Fe aluminum alloy.

[0010] Furthermore, the Fe content is 0.8% to 1.0% by mass, and the recycled aluminum material accounts for 90% to 100% of the Al-Si-Cu-Fe aluminum alloy by mass. This breaks through the upper limit of Fe content, significantly reducing product costs and increasing the source of recycled aluminum material.

[0011] Furthermore, the aluminum alloy is composed of the following components by mass percentage: Si: 7%–10%; Cu: 0.2%–1.3%; Fe: 0.2%–0.8%; Mg: 0.15%–0.4%; Mn: 0.2%–1.0%; Cr: 0.1%–0.5%; Ni: 0.03%–0.07%; Nb: 0.03%–0.07%; RE: 0.05%–0.15%; Ti: 0.08%–0.2%; Sr: 0.008%–0.02%; the remainder being aluminum.

[0012] Another object of the present invention is to provide a method for preparing a high-strength, high-toughness, heat-free Al-Si-Cu-Fe aluminum alloy with high Fe content using the above-described preparation method.

[0013] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0014] (1) After preheating the pretreated recycled aluminum material and other aluminum materials, add them to the melting furnace and heat them to 740℃~750℃ to melt them and obtain the basic aluminum liquid;

[0015] (2) According to the raw material ratio, add preheated Al-Si and Al-Cu master alloys, 75% to 77% manganese agent and 74% to 76% chromium agent to aluminum liquid at 740℃ to 750℃, stir manually for 10 to 15 minutes, and then keep at 740℃ to 750℃ for 15 to 20 minutes; then add Al-Ti, Al-Ni, Al-Nb master alloys and RE to aluminum liquid, stir manually for 10 to 15 minutes, and then take a sample for chemical composition detection;

[0016] (3) After the alloy chemical composition is qualified, the refining agent is evenly sprayed into the aluminum liquid at 740℃~750℃ and refined for 10 minutes~15 minutes. After refining, it is left to stand for 15 minutes~20 minutes to allow the refining agent to fully react and float. The slag formed on the surface of the aluminum liquid is removed. The temperature of the aluminum liquid is reduced to 720℃~730℃, and inert gas is introduced into the aluminum liquid for degassing treatment for 10 minutes~15 minutes. After degassing, the surface slag is removed. Preheated pure magnesium ingots and Al-Sr master alloy are added to the aluminum liquid. The frequency of electromagnetic stirring is 20Hz~30Hz. After electromagnetic stirring for 10 minutes~15 minutes, it is left to stand for 15 minutes~20 minutes. The surface slag is removed and samples are taken to test the chemical composition.

[0017] (4) Cool the aluminum liquid from step (3) to 680℃~700℃, and then use the die casting machine to perform high pressure casting to form a die casting product of Al-Si-Cu-Fe aluminum alloy with high Fe content.

[0018] In step (1), the pretreatment of recycled aluminum includes sorting, crushing, iron removal, and paint removal.

[0019] In step (1), the recycled aluminum material and other aluminum materials are preheated to 180℃~200℃.

[0020] In step (2), the intermediate alloy, manganese agent, chromium agent and mixed rare earth RE are preheated to 180℃~200℃.

[0021] In step (3), the inert gas is either nitrogen or argon.

[0022] In step (3), the preheating temperature of the pure magnesium block and intermediate alloy is 180℃~200℃.

[0023] In step (4), the ultrasonic vibration frequency is 20KHz~25KHz, the power is 2000W~3000W, and the stirring time is generally 15s~30s.

[0024] In step (4), the high-pressure casting is vacuum die casting. During vacuum die casting, the vacuum degree in the mold cavity is less than 100 mbar to reduce the porosity in the casting. The mold temperature is 150℃~200℃ and the aluminum liquid temperature is 680℃~700℃.

[0025] It is common knowledge that Fe in aluminum alloys readily forms acicular β-Al5FeSi phases with Al and Si, deteriorating the toughness of the alloy and castings. Adding elements such as Mn and Cr can promote the transformation of long, acicular Fe-rich phases into skeletal or blocky α-Al(FeMn)Si, mitigating the detrimental effect of Fe-rich phases on alloy toughness. However, when Fe exceeds 0.2%, the presence of numerous large, short, rod-shaped, skeletal, or blocky Fe-rich phases in the aluminum alloy will also reduce the elongation at break (A) of the casting.

[0026] The key technical feature of the Al-Si-Cu-Fe aluminum alloy provided by this invention is that it uses a mixture of recycled aluminum and pure aluminum ingots or recycled aluminum as the base melt. By strictly controlling the molar ratio of Ni, Nb, and RE elements with Fe, Mn, and Cr elements, and combining the strong shearing effect of ultrasonic waves with the rapid cooling effect of vacuum die casting, the interaction between Fe, Mn, and Cr elements and Ni, Nb, and RE elements is promoted. This increases the solubility of Fe elements in the α-Al matrix, ensuring that most Fe elements exist in the matrix in the form of solid solution atoms, and reducing the probability of Fe elements accumulating at grain boundaries to form needle-like, skeletal, or blocky Fe-rich phases. In addition, the Fe-rich phase remaining at the grain boundaries transforms from the larger Al(FeMn / Cr)Si phase into the smaller blocky or granular Al(FeMnCrNi)SiCu phase, with a size of about 500 nm to 3 μm. The molar ratio of Fe:Mn:Cr:Ni:Si:Cu in this phase is (19 to 22):(18 to 29):(8 to 11):(1.5 to 3):(28 to 38):(1 to 2).

[0027] The tensile properties of the Al-Si-Cu-Fe aluminum alloy provided by this invention at room temperature are shown in Table 1. The specified plastic elongation strength R is given when 0.2% ≤ Fe < 0.3%. p0.2 The tensile strength is 132MPa to 140MPa, and the tensile strength R is... m For a strength of 275 MPa to 290 MPa and an elongation at break (A) of 14% to 15%; when 0.3% ≤ Fe < 0.6%, the specified plastic extension strength (R) is... p0.2 The tensile strength R is between 135 MPa and 161 MPa. m For a strength of 280 MPa to 310 MPa and an elongation at break (A) of 11% to 14%; when 0.6% ≤ Fe < 0.8%, the specified plastic extension strength (R) is... p0.2 Tensile strength R is 150MPa~166MPa. mFor a strength of 269 MPa to 315 MPa and an elongation at break (A) of 7% to 12%; when 0.8% ≤ Fe ≤ 1.0%, the specified plastic extension strength (R) is... p0.2 The tensile strength is 155MPa to 169MPa, and the tensile strength R is... m The strength is 264 MPa to 280 MPa and the elongation after fracture (A) is 7% to 9%.

[0028] The tensile properties of the Al-Si-Cu-Fe aluminum alloy provided by this invention at 150℃ are shown in Table 2. The specified plastic elongation strength R is given when 0.2% ≤ Fe < 0.3%. p0.2 The tensile strength is 125MPa to 134MPa, and the tensile strength R is... m For a strength of 258 MPa to 269 MPa and an elongation at break (A) of 15% to 16%; when 0.3% ≤ Fe < 0.6%, the specified plastic extension strength (R) is... p0.2 The tensile strength is 130MPa to 152MPa, and the tensile strength R is... m For a strength of 270 MPa to 285 MPa and an elongation at break (A) of 11% to 14%; when 0.6% ≤ Fe < 0.8%, the specified plastic tensile strength (R) is... p0.2 The tensile strength is 147MPa to 156MPa, and the tensile strength R is... m For a strength of 265 MPa to 290 MPa and an elongation at break (A) of 8% to 11%; when 0.8% ≤ Fe ≤ 1.0%, the specified plastic extension strength (R) is... p0.2 The tensile strength R is 153MPa to 162MPa. m The strength is 258 MPa to 272 MPa and the elongation after fracture (A) is 6% to 9%.

[0029] As the Fe content increases, the elongation at break (A) of the Al-Si-Cu-Fe aluminum alloy provided by this invention gradually decreases, which is consistent with common sense; while the specified plastic elongation strength (R) p0.2 The value gradually increases. The improved mechanical properties of the Al-Si-Cu-Fe aluminum alloy of this invention are mainly due to the combined effects of solid solution strengthening, grain refinement strengthening, Fe-rich particle phase strengthening, and self-aging strengthening, among which solid solution strengthening also includes the contribution of Fe. With the increase of Fe content, more Fe element dissolves into the aluminum alloy matrix, resulting in a better solid solution strengthening effect; at the same time, the nanoscale Fe-rich phase particles formed at the grain boundaries can also hinder dislocation movement, thereby improving the specified plastic elongation strength R. p0.2 Especially when 0.8%≤Fe≤1.0%, the comprehensive mechanical properties of the Al-Si-Cu-Fe aluminum alloy provided by this invention are significantly better than those of commercially available die-cast aluminum alloys such as ADC12 and publicly disclosed heat-free aluminum alloys. The elongation after fracture (A) and strength can meet the requirements of wheel hub products.

[0030] Furthermore, die-cast products require baking after painting and / or powder coating to improve their strength.

[0031] Furthermore, the baking temperature for painting die-cast products is 150℃~160℃, and the time is 35 minutes~50 minutes.

[0032] Furthermore, the powder coating baking temperature for die-cast products is 170℃~180℃, and the time is 35 minutes~50 minutes.

[0033] Furthermore, when die-cast products require two treatments, powder coating and painting, the powder coating baking temperature is 170℃~180℃ and the time is 35 minutes~50 minutes, while the painting baking temperature is 150℃~160℃ and the time is 35 minutes~50 minutes.

[0034] Furthermore, die-cast products require relevant heat treatment to improve strength and elongation after fracture (A), and simple aging treatment is added to improve product strength.

[0035] Annealing and post-aging treatments can also be performed to improve the elongation at break (A) of die-cast products.

[0036] The simple aging treatment is performed by holding at 160℃ to 200℃ for 60 to 180 minutes. The annealing treatment is performed by holding at 320℃ to 350℃ for 5 to 10 minutes, followed by the aging treatment by holding at 160℃ to 200℃ for 180 to 240 minutes.

[0037] The Al-Si-Cu-(0.5%~0.8%)Fe aluminum alloy die-cast wheel hub product provided by this invention has a specified plastic elongation strength R at room temperature after painting and baking. p0.2 ≥165MPa, tensile strength R m ≥300MPa, elongation after fracture A≥7.5%.

[0038] The Al-Si-Cu-(0.5%~0.8%)Fe aluminum alloy die-cast wheel hub product provided by this invention has a specified plastic elongation strength R at room temperature after powder spraying and baking. p0.2 ≥168MPa, tensile strength R m ≥310MPa, elongation after fracture A≥7.5%.

[0039] The Al-Si-Cu-(0.5%~0.8%)Fe aluminum alloy provided by this invention, after simple aging treatment, exhibits a specified ductile elongation strength R at room temperature. p0.2 ≥180MPa, tensile strength R m ≥320MPa, elongation after fracture A≥6%.

[0040] The Al-Si-Cu-(0.8%~1.0%)Fe aluminum alloy die-cast wheel hub product provided by this invention has a specified plastic elongation strength R at room temperature after painting and baking. p0.2 ≥171MPa, tensile strength R m ≥305MPa, elongation after fracture A≥7%.

[0041] The Al-Si-Cu-(0.8%~1.0%)Fe aluminum alloy die-cast wheel hub product provided by this invention has a specified plastic elongation strength R at room temperature after powder spraying and baking. p0.2 ≥173MPa, tensile strength R m ≥310MPa, elongation after fracture A≥7%.

[0042] The Al-Si-Cu-(0.8%~1.0%)Fe aluminum alloy provided by this invention, after simple aging treatment, exhibits a specified ductile elongation strength R at room temperature. p0.2 ≥181MPa, tensile strength R m ≥314MPa, elongation after fracture A≥6%.

[0043] The technical features related to this invention, especially the process flow and parameters of the preparation process, are one of the key links to ensure the solubility of Fe in the aluminum matrix. These process flows and related parameters are matched with the composition ratio of the alloy, which can improve the solid solubility of Fe and refine the Fe-rich phase, thereby ensuring the strength and toughness of high Fe heat-free aluminum alloy materials.

[0044] As is well known, rare earth elements can significantly reduce the hydrogen, oxygen, and sulfur content in aluminum alloys, playing a role in refining and purifying them. RE mixed rare earth elements can also improve the mechanical properties of aluminum alloys through solid solution strengthening, grain refinement strengthening, and second-phase strengthening. While mixed rare earth elements are relatively inexpensive, and Nb and Ni elements are more expensive, their addition amounts are relatively small, with the optimal ratio controlled below 0.1%. Furthermore, the tolerance for Fe in heat-treated aluminum alloys can be increased to 1.0%, ensuring that 50%–100% recycled aluminum can be added to the raw materials. This not only expands the source of recycled aluminum and reduces the overall cost of aluminum alloy materials but also reduces carbon emissions from materials and structural components. Compared to existing heat-treated aluminum alloys with low Fe content (no more than 0.2%) produced from pure aluminum ingots or primary aluminum, this method offers significant cost and carbon emission advantages. This invention uses lower-priced raw aluminum materials, such as ADC12 and other waste machine casings, to replace some of the refined aluminum materials, such as industrial profiles and beverage cans. It can even eliminate the need for pure aluminum ingots or primary aluminum, which not only expands the sources of raw materials but also reduces procurement costs and achieves zero carbon emissions from raw materials.

[0045] The beneficial effects of this invention are as follows:

[0046] (1) Using recycled aluminum as the main raw material, the tolerance of Fe element in high-performance aluminum alloy materials has been improved, up to a maximum of 1.0%, which reduces the amount of aluminum materials such as wrought aluminum, aluminum ingots, and primary aluminum with relatively high costs, thereby reducing carbon emissions and production costs. It expands the application of recycled aluminum in high-strength and tough die-cast aluminum alloy materials and load-bearing components in automobiles, motorcycles, and aerospace.

[0047] (2) The molar fraction ratio of Ni, Nb and RE elements to Mn and Cr elements was optimized. Using this ratio, the solubility of Fe element in the aluminum matrix in high Fe content aluminum-silicon alloy was significantly improved and the Fe-rich phase at the grain boundary was refined, thereby significantly improving the strength and elongation after fracture A of Al-Si-Cu-Fe aluminum alloy, meeting the mechanical performance requirements of load-bearing components such as automobile and motorcycle wheel hubs.

[0048] (3) Using recycled aluminum with a high Fe content as the main material, and without the need for heat treatment, such as the solution treatment plus aging treatment included in T6 treatment, a higher dispersion strengthening effect can be achieved. This method reduces the adverse effects of acicular, skeletal, and blocky Fe on the strength and toughness of aluminum alloy materials and castings, while avoiding problems such as deformation and surface blistering of die-cast products during high-temperature solution treatment, thus providing a material basis for the industrial application of die-cast wheels. Therefore, this alloy has extremely high market application value.

[0049] (4) The present invention provides an Al-Si-Cu-Fe aluminum alloy prepared by the above-mentioned preparation process, which can use recycled aluminum materials with high Fe content, such as ADC12 raw aluminum, with an Fe content of 0.9% to 1.3%. When the Fe content reaches 0.8% to 1.0%, the material and die-cast products still have a high elongation after fracture of A7% to 8%, which expands the raw materials of recycled aluminum and can be used for load-bearing components such as automobile and motorcycle wheel hubs. Compared with the traditional A356 aluminum alloy used in low-pressure and gravity wheel hubs, it has obvious comprehensive cost advantages and carbon emission advantages. Attached Figure Description

[0050] Figure 1(a) is a micrograph of the Fe element distribution in the Al-Si-Cu-0.6%Fe aluminum alloy of Example 4, specifically a superimposed distribution diagram of elements such as Fe, Ni, Nb, Al and Si;

[0051] Figure 1(b) is a micrograph of the Fe element distribution in the Al-Si-Cu-0.6%Fe aluminum alloy of Example 4, specifically a single Fe element distribution diagram;

[0052] Figure 2(a) is a micrograph of the Fe element distribution in the Al-Si-Cu-0.6%Fe aluminum alloy of Comparative Example 1, specifically a superimposed distribution diagram of elements such as Fe, Nb, Al and Si;

[0053] Figure 2(b) is a micrograph of the Fe element distribution in the Al-Si-Cu-0.6%Fe aluminum alloy of Comparative Example 1, specifically the distribution diagram of the corresponding single Fe element.

[0054] Fe content (%) The image shows a 1000X SEM image of the Al-Si-Cu-0.6%Fe aluminum alloy of Example 4.

[0055] Tensile strength Rm (MPa) The image shows a 15000X SEM image of the Al-Si-Cu-0.6%Fe aluminum alloy of Example 4.

[0056] Elongation at break A (%) The image shows a 1000X SEM image of the Al-Si-Cu-0.6%Fe aluminum alloy of Comparative Example 1.

[0057] Fe content (%) The image shows the microstructure (SEM) of the tensile fracture surface of the Al-Si-Cu-0.8%Fe aluminum alloy in Example 4.

[0058] Tensile strength Rm (MPa) The image shows the microstructure (SEM) of the tensile fracture surface of the Al-Si-Cu-0.6%Fe aluminum alloy in Comparative Example 1. Detailed Implementation

[0059] To better understand the above-mentioned objectives, features, and advantages of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in these embodiments can be combined with each other.

[0060] The following embodiments will help those skilled in the art to further understand the present invention. However, the present invention can also be implemented in other ways different from those described herein, therefore the scope of protection of the present invention is not limited to the specific embodiments disclosed below. It should be noted that those skilled in the art can make several modifications and improvements without departing from the concept of the present invention. These all fall within the scope of protection of the present invention.

[0061] During material feeding, the weights of the intermediate alloy and flux additives are calculated based on the expected total alloy mass, the set element content ratios in the aluminum alloy, and the percentage content of each element in the intermediate alloy. This is a method known to those skilled in the art.

[0062] Example 1

[0063] The present invention provides a method for preparing a heat-free Al-Si-Cu-0.2%Fe aluminum alloy based on recycled aluminum and pure aluminum ingots. Recycled aluminum accounts for 30% of the total mass of the raw materials, which are aluminum cans with an Fe content of 0.42%. Pure aluminum ingots account for 70% of the mass and have an Fe content of 0.1%. The target chemical composition of the alloy, by mass percentage, is 9.0% Si, 1.0% Cu, 0.2% Fe, 0.3% Mg, 0.6% Mn, 0.4% Cr, 0.1% Ti, 0.03% Ni, 0.03% Nb, 0.05% RE, and 0.01% Sr, with the balance being Al and unavoidable impurity elements. The preparation process is as follows:

[0064] (1) 330 kg of pretreated aluminum cans (i.e., those with iron removed by magnetic separation) were mixed with 715 kg of pure aluminum ingots (with a yield of approximately 98%) in a resistance furnace after considering burn-off. The mixture was heated to 750 °C and, after complete melting, stirred and a sample was taken from 20 cm below the liquid surface for composition analysis. The composition by mass percentage was 0.21% Fe and 0.11% Mg. Some magnesium was lost due to burn-off, and the remainder consisted of Al and unavoidable impurities. Other elements such as Cr and Mn were negligible. The surface dross was removed, yielding approximately 1000 kg of basic aluminum liquid. The poor quality was mainly due to burn-off, which was removed as surface dross.

[0065] (2) According to the alloy raw material ratio requirements, add 429 kg of Al-30Si master alloy, 50 kg of Al-30Cu master alloy, 12 kg of 75% manganese agent and 8 kg of 75% chromium agent preheated to 180℃ to the aluminum liquid at 750℃. After all the alloy raw materials are melted, stir manually for 10 minutes and keep warm at 740℃ for 15 minutes. Add 15 kg of Al-10Ti master alloy, 4.6 kg of Al-10Ni master alloy and 4.6 kg of Al-10Nb master alloy preheated to 180℃ and 0.8 kg of RE mixed rare earth to the aluminum liquid. The RE is lanthanum-cerium mixed rare earth. After all the alloy raw materials are melted, stir manually for 10 minutes and take samples for chemical composition analysis.

[0066] (3) After refining the molten aluminum at 740℃ for 10 minutes, let it stand for 15 minutes and remove the dross formed on the surface of the molten aluminum. Lower the temperature of the molten aluminum to 720℃ and introduce inert gas for degassing for 10 minutes; after degassing, remove the surface dross. Add 3.5 kg of pure magnesium ingot and 1.5 kg of Al-10Sr master alloy to the molten aluminum, melt it, and stir the molten aluminum with an electromagnetic field of 20 Hz for 15 minutes, then let it stand for 20 minutes and remove the surface dross. Take a composition test sample to test the composition.

[0067] (4) After the chemical composition is qualified, the actual composition is 9.16% Si, 0.94% Cu, 0.22% Fe, 0.32% Mg, 0.58% Mn, 0.40% Cr, 0.092% Ti, 0.034% Ni, 0.032% Nb, 0.05% RE and 0.013% Sr, with the balance being Al and unavoidable impurity elements. The aluminum liquid is cooled to 700℃ and transferred to the die-casting machine's side furnace via a transfer ladle. The aluminum liquid in the die-casting machine's ladle is ultrasonically stirred at 20KHz for 30s. Tensile test bars are formed on a 400T die-casting machine, with each piece using approximately 1kg of aluminum, resulting in 30 tensile test specimens. Die-cast wheel hubs are also formed on a 1250T die-casting machine, with each piece using approximately 6kg of aluminum, resulting in 50 wheel hubs. Finally, the formed parts are painted or powder-coated and baked.

[0068] The Al-Si-Cu-0.2%Fe aluminum alloy prepared in this embodiment was tested according to the standard ASTM B557-06. It was die-cast into a 6.4 mm diameter round bar with a gauge length of 64 mm for tensile testing. The average specified plastic elongation strength R at room temperature was... p0.2 The average tensile strength is 132 MPa, and the average tensile strength R is... m The strength is 285 MPa, and the average elongation after fracture (A) is 15.3%. For die-cast wheel hubs and other products, direct sampling and testing were conducted on the product itself, and the average specified plastic extension strength (R) at room temperature was... p0.2 The average tensile strength is 129 MPa, and the average tensile strength R is... m The average elongation after fracture (A) is 14%; the average specified plastic extension strength (R) of painted wheel hubs and other products is 268 MPa. p0.2 The average tensile strength is 143 MPa, and the average tensile strength R is... m The strength is 279 MPa, and the average elongation after fracture (A) is 8.6%.

[0069] Example 2

[0070] The present invention provides a method for preparing a heat-free Al-Si-Cu-0.4Fe aluminum alloy based on recycled aluminum and pure aluminum ingots. The recycled aluminum raw materials used include aluminum cans after magnetic separation to remove iron, with an iron content of 0.44%, and ADC12 waste casings after crushing and degreasing treatment, wherein the iron content is 1.05%, the silicon content is 10.5%, and the copper content is 1.86%. The target chemical composition of the alloy, by mass percentage, is 9.0% Si, 1.0% Cu, 0.4% Fe, 0.3% Mg, 0.6% Mn, 0.4% Cr, 0.1% Ti, 0.04% Ni, 0.04% Nb, 0.1% RE, and 0.01% Sr, with the balance being Al and unavoidable impurity elements.

[0071] This embodiment uses the same preparation method as Example 1, but the ratio of recycled aluminum to aluminum ingots and the amount of related elements added are different. Recycled aluminum accounts for 60% of the total mass of raw materials, of which aluminum cans account for 40% and ADC12 waste casings account for 20%. The final actual chemical composition by mass percentage is 8.82% Si, 1.08% Cu, 0.43% Fe, 0.28% Mg, 0.64% Mn, 0.42% Cr, 0.11% Ti, 0.043% Ni, 0.037% Nb, 0.11% RE, and 0.009% Sr, with the balance being Al and unavoidable impurity elements.

[0072] Example 3

[0073] The present invention provides a method for preparing a heat-free Al-Si-Cu-0.5Fe aluminum alloy based on recycled aluminum and pure aluminum ingots. The target chemical composition of the alloy, by mass percentage, is 9.0% Si, 1.0% Cu, 0.5% Fe, 0.3% Mg, 0.6% Mn, 0.4% Cr, 0.1% Ti, 0.06% Ni, 0.05% Nb, 0.1% RE, and 0.01% Sr, with the balance being Al and unavoidable impurity elements.

[0074] This embodiment uses the same preparation method as Example 1, but the ratio of recycled aluminum to aluminum ingots and the amount of related elements added are different. Recycled aluminum accounts for 60% of the total mass of raw materials, of which aluminum cans account for 30% and ADC12 waste casings account for 30%. The content of Ni and Nb elements is increased to 0.06% and 0.05%, respectively. The final actual chemical composition by mass percentage is 8.97% Si, 1.14% Cu, 0.49% Fe, 0.32% Mg, 0.60% Mn, 0.41% Cr, 0.092% Ti, 0.058% Ni, 0.049% Nb, 0.094% RE, and 0.013% Sr, with the balance being Al and unavoidable impurity elements.

[0075] Example 4

[0076] The present invention provides a method for preparing a heat-free Al-Si-Cu-0.6Fe aluminum alloy based on recycled aluminum and pure aluminum ingots. The target chemical composition of the alloy, by mass percentage, is 9.0% Si, 1.0% Cu, 0.6% Fe, 0.3% Mg, 0.6% Mn, 0.4% Cr, 0.01% Ti, 0.06% Ni, 0.05% Nb, 0.1% RE, and 0.01% Sr, with the balance being Al and unavoidable impurity elements.

[0077] This embodiment uses the same preparation method as Example 1, but the ratio of recycled aluminum to aluminum ingots and the amount of related elements added are different. Recycled aluminum accounts for 70% of the total mass of raw materials, of which aluminum cans account for 20% and ADC12 waste casings account for 50%. The final actual chemical composition by mass percentage is 9.2% Si, 1.06% Cu, 0.63% Fe, 0.33% Mg, 0.61% Mn, 0.43% Cr, 0.097% Ti, 0.063% Ni, 0.052% Nb, 0.11% RE, and 0.011% Sr, with the balance being Al and unavoidable impurity elements.

[0078] Example 5

[0079] The present invention provides a method for preparing a heat-free Al-Si-Cu-0.7Fe aluminum alloy based on recycled aluminum and pure aluminum ingots. The target chemical composition of the alloy, by mass percentage, is 9.0% Si, 1.0% Cu, 0.7% Fe, 0.3% Mg, 0.6% Mn, 0.4% Cr, 0.01% Ti, 0.06% Ni, 0.05% Nb, 0.1% RE and 0.01% Sr, with the balance being Al and unavoidable impurity elements.

[0080] This embodiment uses the same preparation method as Example 1, but the ratio of recycled aluminum to aluminum ingots and the amount of related elements added are different. Recycled aluminum accounts for 80% of the total mass of raw materials, of which aluminum cans account for 20% and ADC12 waste casings account for 60%. The final actual chemical composition by mass percentage is 8.96% Si, 1.02% Cu, 0.72% Fe, 0.32% Mg, 0.58% Mn, 0.43% Cr, 0.098% Ti, 0.061% Ni, 0.052% Nb, 0.098% RE, and 0.009% Sr, with the balance being Al and unavoidable impurity elements.

[0081] Example 6

[0082] The present invention provides a method for preparing a heat-free Al-Si-Cu-0.8Fe aluminum alloy based on recycled aluminum and pure aluminum ingots. The target chemical composition of the alloy, by mass percentage, is 9.0% Si, 1.0% Cu, 0.8% Fe, 0.3% Mg, 0.6% Mn, 0.4% Cr, 0.1% Ti, 0.07% Ni, 0.07% Nb, 0.12% RE and 0.01% Sr, with the balance being Al and unavoidable impurity elements.

[0083] This embodiment uses the same preparation method as Example 1, but with adjustments to the raw material ratio and element addition amounts. Recycled aluminum accounts for 95% of the total raw material mass, of which aluminum cans account for 30% and ADC12 waste casings account for 65%. The final actual chemical composition by mass percentage is 9.12% Si, 1.1% Cu, 0.79% Fe, 0.33% Mg, 0.62% Mn, 0.40% Cr, 0.11% Ti, 0.072% Ni, 0.068% Nb, 0.12% RE, and 0.013% Sr, with the balance being Al and unavoidable impurity elements.

[0084] Example 7

[0085] The present invention provides a method for preparing a heat-free Al-Si-Cu-1.0Fe aluminum alloy based on recycled aluminum. The target chemical composition of the alloy, by mass percentage, is 9.0% Si, 1.2% Cu, 1.0% Fe, 0.3% Mg, 0.8% Mn, 0.6% Cr, 0.1% Ti, 0.1% Ni, 0.08% Nb, 0.15% RE, and 0.01% Sr, with the balance being Al and unavoidable impurity elements.

[0086] This embodiment uses the same preparation method as Example 1, but uses recycled aluminum as the raw material, accounting for 100% of the total raw material mass. Of this, aluminum cans account for 35%, and ADC12 waste casings account for 65%. 20% of the aluminum can raw material was not magnetically separated. The amounts of relevant elements added were adjusted accordingly. The final actual chemical composition, by mass percentage, is 9.24% Si, 1.24% Cu, 1.08% Fe, 0.29% Mg, 0.83% Mn, 0.58% Cr, 0.092% Ti, 0.096% Ni, 0.073% Nb, 0.16% RE, and 0.012% Sr, with the balance being Al and unavoidable impurity elements.

[0087] Example 8

[0088] The present invention provides a method for preparing a heat-free Al-Si-Cu-0.6Fe aluminum alloy based on recycled aluminum and pure aluminum ingots. The target chemical composition of the alloy, by mass percentage, is 9.0% Si, 0.5% Cu, 0.6% Fe, 0.3% Mg, 0.6% Mn, 0.4% Cr, 0.1% Ti, 0.06% Ni, 0.05% Nb, 0.1% RE and 0.01% Sr, with the balance being Al and unavoidable impurity elements.

[0089] This embodiment uses the same preparation method as Example 1, and the chemical composition of the aluminum alloy prepared in Example 4 is similar, except that the Cu content is reduced from 1% to 0.5%, while other components remain unchanged. To ensure that the Cu content is close to 0.5%, recycled aluminum accounts for 75% of the total mass of the raw materials, of which aluminum cans account for 45% and ADC12 waste casings account for 30%. The final actual chemical composition by mass percentage is 8.99% Si, 0.53% Cu, 0.59% Fe, 0.33% Mg, 0.61% Mn, 0.40% Cr, 0.098% Ti, 0.061% Ni, 0.053% Nb, 0.113% RE, and 0.013% Sr, with the balance being Al and unavoidable impurity elements.

[0090] Example 9

[0091] The present invention provides a method for preparing a heat-free Al-Si-Cu-0.6Fe aluminum alloy based on recycled aluminum and pure aluminum ingots. The target chemical composition of the alloy, by mass percentage, is 9.0% Si, 1.0% Cu, 0.60% Fe, 0.3% Mg, 0.4% Mn, 0.4% Cr, 0.1% Ti, 0.06% Ni, 0.05% Nb, 0.1% RE, and 0.01% Sr, with the balance being Al and unavoidable impurity elements.

[0092] This embodiment uses the same preparation method as Example 1, and the chemical composition of the aluminum alloy prepared in Example 4 is similar, except that the Mn content is reduced from 0.6% to 0.4%, while other components remain unchanged. The final actual chemical composition by mass percentage is 9.18% Si, 0.97% Cu, 0.60% Fe, 0.29% Mg, 0.43% Mn, 0.42% Cr, 0.103% Ti, 0.062% Ni, 0.049% Nb, 0.105% RE, and 0.011% Sr, with the balance being Al and unavoidable impurity elements.

[0093] Example 10

[0094] The present invention provides a method for preparing a heat-free Al-Si-Cu-0.6Fe aluminum alloy based on recycled aluminum and pure aluminum ingots. The target chemical composition of the alloy, by mass percentage, is 9.0% Si, 1.0% Cu, 0.60% Fe, 0.3% Mg, 0.6% Mn, 0.2% Cr, 0.1% Ti, 0.06% Ni, 0.05% Nb, 0.1% RE, and 0.01% Sr, with the balance being Al and unavoidable impurity elements.

[0095] This embodiment uses the same preparation method as Example 1, and the chemical composition of the aluminum alloy prepared in Example 4 is similar, except that the Cr content is reduced from 0.4% to 0.2%, while the other components remain unchanged. The final actual chemical composition by mass percentage is 9.21% Si, 1.12% Cu, 0.63% Fe, 0.35% Mg, 0.57% Mn, 0.18% Cr, 0.12% Ti, 0.063% Ni, 0.054% Nb, 0.12% RE, and 0.089% Sr, with the balance being Al and unavoidable impurity elements.

[0096] Example 11

[0097] The present invention provides a method for preparing a heat-free Al-Si-Cu-0.6Fe aluminum alloy based on recycled aluminum and pure aluminum ingots. The target chemical composition of the alloy, by mass percentage, is 9.0% Si, 1.0% Cu, 0.60% Fe, 0.3% Mg, 0.6% Mn, 0.4% Cr, 0.1% Ti, 0.04% Ni, 0.03% Nb, 0.1% RE, and 0.01% Sr, with the balance being Al and unavoidable impurity elements.

[0098] This embodiment uses the same preparation method as Example 1, and the chemical composition of the aluminum alloy prepared in Example 4 is similar, except that the Ni content is reduced from 0.06% to 0.04%, and the Nb content is reduced from 0.05% to 0.03%, while other components remain unchanged. The final actual chemical composition, by mass percentage, is 8.82% Si, 0.94% Cu, 0.57% Fe, 0.31% Mg, 0.65% Mn, 0.38% Cr, 0.11% Ti, 0.037% Ni, 0.033% Nb, 0.96% RE, and 0.013% Sr, with the balance being Al and unavoidable impurity elements.

[0099] Example 12

[0100] The present invention provides a method for preparing a heat-free Al-Si-Cu-0.6Fe aluminum alloy based on recycled aluminum and pure aluminum ingots. The target chemical composition of the alloy, by mass percentage, is 9.0% Si, 1.0% Cu, 0.60% Fe, 0.3% Mg, 0.6% Mn, 0.4% Cr, 0.1% Ti, 0.06% Ni, 0.05% Nb, 0.06% RE, and 0.01% Sr, with the balance being Al and unavoidable impurity elements.

[0101] This embodiment uses the same preparation method as Example 1, and the chemical composition of the aluminum alloy prepared in Example 4 is similar, except that the RE content is reduced from 0.1% to 0.06%, while other components remain unchanged. The final actual chemical composition by mass percentage is 9.38% Si, 1.13% Cu, 0.59% Fe, 0.31% Mg, 0.64% Mn, 0.44% Cr, 0.12% Ti, 0.064% Ni, 0.049% Nb, 0.057% RE, and 0.095% Sr, with the balance being Al and unavoidable impurity elements.

[0102] Example 13

[0103] The present invention provides a method for preparing a heat-free Al-Si-Cu-0.8Fe aluminum alloy based on recycled aluminum and pure aluminum ingots. The target chemical composition of the alloy, by mass percentage, is 9.0% Si, 1.0% Cu, 0.80% Fe, 0.3% Mg, 0.6% Mn, 0.4% Cr, 0.1% Ti, 0.06% Ni, 0.06% Nb, 0.1% RE, and 0.01% Sr, with the balance being Al and unavoidable impurity elements.

[0104] This embodiment uses the same preparation method as Example 1. Compared with the aluminum alloy prepared in Example 6, the Ni and Nb content decreased from 0.07% to 0.05%, and the RE content decreased from 0.12% to 0.1%, while other components remained unchanged. The final actual chemical composition by mass percentage is 9.05% Si, 0.98% Cu, 0.83% Fe, 0.33% Mg, 0.63% Mn, 0.41% Cr, 0.10% Ti, 0.062% Ni, 0.059% Nb, 0.095% RE, and 0.011% Sr, with the balance being Al and unavoidable impurity elements.

[0105] Example 14

[0106] The present invention provides a method for preparing a heat-free Al-Si-Cu-1.0Fe aluminum alloy based on recycled aluminum. The target chemical composition of the alloy, by mass percentage, is 9.0% Si, 1.2% Cu, 1.0% Fe, 0.3% Mg, 0.8% Mn, 0.5% Cr, 0.1% Ti, 0.07% Ni, 0.08% Nb, 0.1% RE, and 0.01% Sr, with the balance being Al and unavoidable impurity elements.

[0107] This embodiment uses the same preparation method as Example 1. Compared with the aluminum alloy prepared in Example 7, the Ni content is reduced from 1.0% to 0.7%, the RE content is reduced from 0.15% to 0.1%, and other components remain unchanged. The final actual chemical composition by mass percentage is 9.4% Si, 1.25% Cu, 1.08% Fe, 0.34% Mg, 0.74% Mn, 0.48% Cr, 0.13% Ti, 0.067% Ni, 0.082% Nb, 1.03% RE, and 0.012% Sr, with the balance being Al and unavoidable impurity elements.

[0108] Comparative Example 1

[0109] The present invention provides a method for preparing a heat-free Al-Si-Cu-0.6Fe aluminum alloy based on recycled aluminum and pure aluminum ingots. The target chemical composition of the alloy, by mass percentage, is 9.0% Si, 1.0% Cu, 0.6% Fe, 0.3% Mg, 0.6% Mn, 0.4% Cr, 0.1% Ti, 0.05% Nb, 0.1% RE and 0.01% Sr, with the balance being Al and unavoidable impurity elements.

[0110] This comparative example uses the same preparation method as Example 1, and its chemical composition is similar to that of the aluminum alloy prepared in Example 4, except that the Ni content is reduced from 0.06% to 0%, i.e., no Ni is added; the other components remain unchanged. The final actual chemical composition, by mass percentage, is 9.08% Si, 0.96% Cu, 0.57% Fe, 0.28% Mg, 0.64% Mn, 0.43% Cr, 0.093% Ti, 0.053% Nb, 0.12% RE, and 0.01% Sr, with the balance being Al and unavoidable impurity elements.

[0111] Comparative Example 2

[0112] The present invention provides a method for preparing a heat-free Al-Si-Cu-0.6Fe aluminum alloy based on recycled aluminum and pure aluminum ingots. The target chemical composition of the alloy, by mass percentage, is 9.0% Si, 1.0% Cu, 0.6% Fe, 0.3% Mg, 0.6% Mn, 0.4% Cr, 0.1% Ti, 0.06% Ni, 0.1% RE and 0.01% Sr, with the balance being Al and unavoidable impurity elements.

[0113] This comparative example uses the same preparation method as Example 1, and its chemical composition is similar to that of the aluminum alloy prepared in Example 4. The only difference is that the Nb content is reduced from 0.05% to 0%, meaning no Nb is added; all other components remain unchanged. The final actual chemical composition, by mass percentage, is 9.06% Si, 1.07% Cu, 0.63% Fe, 0.34% Mg, 0.61% Mn, 0.44% Cr, 0.11% Ti, 0.059% Ni, 0.107% RE, and 0.011% Sr, with the balance being Al and unavoidable impurity elements.

[0114] Comparative Example 3

[0115] The present invention provides a method for preparing a heat-free Al-Si-Cu-0.6Fe aluminum alloy based on recycled aluminum and pure aluminum ingots. The target chemical composition of the alloy, by mass percentage, is 9.0% Si, 1.0% Cu, 0.6% Fe, 0.3% Mg, 0.6% Mn, 0.4% Cr, 0.1% Ti, 0.06% Ni, 0.05% Nb, and 0.01% Sr, with the balance being Al and unavoidable impurity elements.

[0116] This comparative example uses the same preparation method as Example 1, and its chemical composition is similar to that of the aluminum alloy prepared in Example 4. The only difference is that the RE element content is reduced from 0.1% to 0%, meaning no RE element is added; other components remain unchanged. The final actual chemical composition, by mass percentage, is 8.89% Si, 1.1% Cu, 0.58% Fe, 0.32% Mg, 0.58% Mn, 0.41% Cr, 0.12% Ti, 0.063% Ni, 0.05% Nb, and 0.009% Sr, with the balance being Al and unavoidable impurity elements.

[0117] Comparative Example 4

[0118] The present invention provides a method for preparing a heat-free Al-Si-Cu-0.6Fe aluminum alloy based on recycled aluminum and pure aluminum ingots. The target chemical composition of the alloy, by mass percentage, is 9.0% Si, 1.0% Cu, 0.6% Fe, 0.3% Mg, 0.6% Mn, 0.4% Cr, 0.1% Ti, 0.1% Ni, 0.05% Nb, 0.04% RE and 0.01% Sr, with the balance being Al and unavoidable impurity elements.

[0119] This comparative example uses the same preparation method as Example 1 and has a similar chemical composition to the aluminum alloy prepared in Example 4. The only differences are a reduction in the RE content from 0.1% to 0.04% and an increase in the Ni content from 0.06% to 0.1%, while other components remain unchanged. The final actual chemical composition, by mass percentage, is 8.93% Si, 1.2% Cu, 0.64% Fe, 0.31% Mg, 0.58% Mn, 0.38% Cr, 0.11% Ti, 0.098% Ni, 0.049% Nb, 0.037% RE, and 0.01% Sr, with the balance being Al and unavoidable impurity elements.

[0120] Comparative Example 5

[0121] The present invention provides a method for preparing a heat-free Al-Si-Cu-0.8Fe aluminum alloy based on recycled aluminum and pure aluminum ingots. The target chemical composition of the alloy, by mass percentage, is 9.0% Si, 1.0% Cu, 0.8% Fe, 0.3% Mg, 0.6% Mn, 0.4% Cr, 0.1% Ti, 0.15% Ni, 0.03% Nb, 0.04% RE and 0.01% Sr, with the balance being Al and unavoidable impurity elements.

[0122] This comparative example uses the same preparation method as Example 1. Compared with the aluminum alloy prepared in Example 6, only the Nb content was reduced from 0.07% to 0.03% and the RE content was reduced from 0.12% to 0.04%, while the Ni content was increased from 0.07% to 0.15%. Other components remained unchanged. The final actual chemical composition by mass percentage was 8.87% Si, 1.1% Cu, 0.82% Fe, 0.27% Mg, 0.66% Mn, 0.43% Cr, 0.13% Ti, 0.146% Ni, 0.031% Nb, 0.046% RE, and 0.014% Sr, with the balance being Al and unavoidable impurity elements.

[0123] Table 1 shows the tensile properties of the Al-Si-Cu-Fe aluminum alloy provided by this invention at room temperature with different Fe contents.

[0124] Elongation at break A (%) <![CDATA[Specified plastic extension strength R p0.2 (MPa)]]> Fe content (%) Tensile strength Rm (MPa) 0.2～0.3 132～140 275～290 14～15 0.3～0.6 135～161 280～310 11～14 0.6～0.8 150～166 269～315 7～12 0.8～1.0 155～169 264～280 7～9

[0125] Table 2 shows the tensile properties of the Al-Si-Cu-Fe aluminum alloy provided by this invention at 150℃ with different Fe contents.

[0126] Elongation at break A (%) <![CDATA[Specified plastic extension strength R p0.2 (MPa)]]> Example 1 Example 2 0.2～0.3 125～134 258～269 15～16 0.3～0.6 130～152 270～285 11～14 0.6～0.8 147～156 265～290 8～11 0.8～1.0 153～162 258～272 6～9

[0127] Table 3 shows the tensile properties of Examples 1-14 and Comparative Examples 1-5 provided by the present invention at room temperature.

[0128] Example 3 <![CDATA[Specified plastic extension strength R p0.2 (MPa)]]> Example 4 Example 5 Example 6 0.2% 132 285 15.3 Example 7 0.4% 140 287 14.1 Example 8 0.5% 152 294 12.6 Example 9 0.6% 161 315 11.0 Example 10 0.7% 162 283 8.3 Example 11 0.8% 166 279 7.9 Example 12 1.0% 169 280 7.7 Example 13 0.6% 142 273 12 Example 14 0.6% 150 275 9.1 Comparative Example 1 0.6% 153 278 8.2 Comparative Example 2 0.6% 152 269 7.5 Comparative Example 3 0.6% 151 277 8.4 Comparative Example 4 0.8% 155 269 6.9 Comparative Example 5 1.0% 159 264 6.8 Figure 3 0.6% 135 242 2.6 Figure 4 0.6% 130 233 3.0 Figure 5 0.6% 140 248 3.5 Figure 6 0.6% 129 236 3.3 Figure 7 0.8% 134 241 2.2

[0129] As can be seen from Examples 1-14, the solution of the present invention significantly improves the strength and elongation after fracture (A) of Al-Si-Cu-Fe aluminum alloy. Even when the Fe content reaches 0.8% to 1.0%, the material and die-cast products still have high toughness, specifically manifested as good elongation after fracture (A), which expands the application of recycled aluminum raw materials in load-bearing components such as automobile and motorcycle wheel hubs.

[0130] Taking Example 4 as an example, Figure 1(a) and Figure 1(b) Figure 6 and Figure 7 This image shows the Fe element distribution and microstructure of the Al-Si-Cu-0.6%Fe aluminum alloy prepared according to this invention, as captured by microscopy (SEM). It is clearly observed that most of the Fe element in the high-Fe content aluminum-silicon alloy prepared by this invention is dissolved in the aluminum matrix as solid-solution atoms, while a small portion exists as fine nano-sized Fe-rich phase particles at the grain boundaries. No acicular Fe phases, large-sized skeletal or blocky Fe phases were observed in the alloy microstructure. Obviously, the large amount of Fe dissolved in the matrix not only reduces the presence of acicular, skeletal, or blocky Fe-rich phases that affect toughness, thus improving the elongation at break (A) of the aluminum alloy and castings, but also provides better solid-solution strengthening, enhancing the strength of the aluminum alloy and castings.

[0131] Examples 1-7 show that the microstructures of Al-Si-Cu-Fe aluminum alloys with different Fe contents ranging from 0.2% to 1.0% are similar, with the Fe element phase mainly existing as solid solution atoms and fine granular Fe-rich phases; as the Fe content increases, the specified ductile elongation strength R of the alloy increases. p0.2 The strength is significantly improved, mainly due to the increase in tensile strength R. m Due to the solid solution strengthening effect of Fe and the strengthening effect of fine Fe-rich phases, the elongation after fracture (A) decreases slightly; while the elongation at break (R) shows a trend of first increasing and then decreasing. This is mainly because the plastic extension strength (R) is specified. p0.2 This is the result of the combined effect of elongation at break (A). Furthermore, the proportion of recycled aluminum added increased from 30% to 100%, with the proportion of raw aluminum, such as ADC12 waste casings which have relatively low procurement costs and are widely available, increasing from 0% to 65%, while the proportion of refined aluminum, such as aluminum cans, decreased from 40% to 20%. Since refined aluminum typically contains little or no Cu, increasing the proportion of Cu-containing raw aluminum reduces the amount of higher-cost Cu added, lowering raw material procurement costs and expanding the range of recycled aluminum raw material sources.

[0132] Compared to Example 4, Example 8 reduced the Cu content while maintaining the same process parameters. Cu primarily strengthens Al-Si aluminum alloys through solid solution treatment and precipitation of the Al₂Cu phase. Reducing the Cu content has little impact on the alloy's elongation at break (A), while the alloy's specified ductile strength (R) remains unchanged. p0.2 and tensile strength R m Then it decreased.

[0133] Compared to Example 4, Examples 9-10 show a reduction in Mn or Cr content, while the process parameters remain unchanged. Mn and Cr can transform the acicular β-Al5FeSi phase into the blocky α-Al(FeMnCr)Si phase in Al-Si aluminum alloys. In this invention, the main role of Mn and Cr is to interact with Fe, Ni, and other elements to form granular Al(FeMnCrNi)SiCu phase. When the Mn or Cr content decreases, the alloy's specified ductile elongation strength R... p0.2 Tensile strength R m Both the elongation at break (A) and the elongation after fracture decreased.

[0134] Compared with Examples 4, 6, and 7, Examples 11-14 show reduced Ni, Nb, or RE content, while the process parameters remain unchanged. In this invention, the main role of Ni, Nb, and RE is to interact with elements such as Mn and Cr, promoting Fe to dissolve in the aluminum matrix as solid atoms or exist as particulate compounds at grain boundaries. Reducing the Ni, Nb, or RE content affects the alloy's specified ductile elongation strength R. p0.2 Tensile strength R m Both the elongation after fracture (A) and the tensile strength (F) are affected. On the one hand, the solid solution strengthening effect of Fe atoms and the strengthening effect of granular phase decrease. On the other hand, a small amount of blocky Fe-rich phase that affects the toughness of the alloy is generated, leading to a decrease in the mechanical properties of the alloy.

[0135] As can be seen from Comparative Example 1 and Example 4, when the composition of other elements remains unchanged, without the addition of Ni, Nb, or RE elements, even using the same preparation process, the solubility of Fe in the α-Al matrix of the Al-Si alloy prepared in Comparative Example 1 is significantly reduced, as shown in Figures 2(a) and 2(b). Although a small amount of fine blocky or granular Fe-rich phases were also found at the grain boundaries, Fe mainly exists in the form of large-sized skeletal and blocky Al(FeMnCr)Si phases with sizes ranging from 5 μm to 20 μm, as shown in Figures 2(a) and 2(b). ​ These larger Fe-rich phases can easily reduce the toughness and strength of die-cast aluminum alloys, causing fracture failure of aluminum alloy structural components and limiting the application of high Fe-content aluminum-silicon alloys in load-bearing components such as automobile and motorcycle wheels. ​ and ​The tensile fracture morphologies of the Al-Si-Cu-0.6%Fe aluminum alloys prepared in Example 4 and Comparative Example 1 are shown, respectively. It is clearly visible that the alloy prepared in Example 4 exhibits a large number of dimples in its tensile fracture surface. ​ Based on morphology, the fracture mode of the Al-Si-Cu-0.6Fe aluminum alloy prepared in Example 4 is mainly ductile fracture, corresponding to a relatively good elongation after fracture (A) greater than or equal to 10%. In contrast, the fracture mode of the Al-Si-Cu-0.6Fe alloy prepared in Comparative Example 1 is mainly quasi-dissociative fracture, consistent with the characteristics of brittle fracture. Besides the presence of large-area river patterns, dissociation steps, and Fe-rich phases in the fracture surface, see... ​ Simultaneously, obvious secondary cracks appeared. During deformation, stress concentration easily formed on the skeletal or blocky Fe-rich phases, causing cracking of the Fe-rich phases, thus leading to a drop in elongation at break (A) to below 4%. Comparative Examples 1-3 confirm that when elements such as Ni, Nb, and RE are lacking or their proportions are altered, the solubility of Fe in the α-Al matrix of Al-Si-Cu-Fe aluminum alloys significantly decreases. Conversely, a large number of large skeletal or blocky Al(FeMnCr)Si phases are formed in the alloy. These skeletal and blocky Fe phases easily deteriorate the strength and toughness of high-Fe-content aluminum alloys.

[0136] Comparative Example 4 and Example 4 show that the Al-Si-Cu-0.6Fe aluminum alloy material prepared without the addition of the grain refiner Al-Ti alloy has insufficient grain refinement strengthening effect, which also leads to a decrease in the alloy's specified plastic elongation strength R. p0.2 Tensile strength R m The elongation after fracture (A) is relatively low.

[0137] The microstructure and tensile properties of the Al-Si-Cu-0.6Fe aluminum alloy prepared in Comparative Example 5 were similar to those of the aluminum alloy prepared in Comparative Example 1. Despite the increased Ni content, when the Nb and RE contents decreased to below 0.03% and 0.05%, respectively, the solubility of Fe in the aluminum matrix was insufficient. The Fe-rich phase in the alloy still existed in large quantities with a large-sized skeletal or blocky morphology, making it difficult for the alloy's elongation at fracture (A) to reach more than 3%.

[0138] In the description of this specification, the terms "one embodiment," "some embodiments," etc., refer to specific features, structures, materials, or characteristics described in connection with an embodiment or example that are included in at least one embodiment or example of the present invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0139] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made using the present invention, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A high-Fe-content Al-Si-Cu-Fe aluminum alloy, characterized in that, The Al-Si-Cu-Fe aluminum alloy consists of the following components by mass percentage Composition: Si: 7%–10%; Cu: 0.2%–1.3%; Fe: 0.2%~1.0%; Mg: 0.15% ~ 0.4%; Mn: 0.2% ~ 1.0%; Cr: 0.1% ~ 0.5%; Ni: 0.03%~0.15%; Nb: 0.03%~0.15%; RE: 0.05%~0.2%; Ti: 0.08%~0.2%; Sr: 0.008%~0.02%; the remainder is aluminum; Where 0.2% ≤ Fe < 0.3%, the specified plastic elongation strength R of the aluminum alloy is... p0.2 The tensile strength is 132MPa to 140MPa, and the tensile strength R is... m The specified ductile tensile strength R of the aluminum alloy is 275MPa~290MPa and the elongation after fracture A is 14%~15%; when 0.3%≤Fe<0.6%, the specified ductile tensile strength R of the aluminum alloy is... p0.2 The tensile strength R is between 135 MPa and 161 MPa. m The specified ductile tensile strength R of the aluminum alloy is 280MPa~310MPa and the elongation after fracture A is 11%~14%; when 0.6%≤Fe<0.8%, the specified ductile tensile strength R of the aluminum alloy is... p0.2 Tensile strength R is 150MPa~166MPa. m The specified ductile tensile strength R of the aluminum alloy is 269 MPa to 315 MPa and the elongation after fracture A is 7% to 12%; when 0.8% ≤ Fe ≤ 1.0%, the specified ductile tensile strength R of the aluminum alloy is... p0.2 The tensile strength is 155MPa to 169MPa, and the tensile strength R is... m The strength is 264 MPa to 280 MPa and the elongation after fracture (A) is 7% to 9%.

2. The Al-Si-Cu-Fe aluminum alloy with high Fe content according to claim 1, characterized in that, The aluminum is derived from recycled aluminum and other aluminum materials. The recycled aluminum materials include one or more combinations of waste machine housings, beverage cans, profiles, aluminum wires, or scrapped aluminum materials from automobiles. The mass of the recycled aluminum materials accounts for 30% to 100% of the mass of the Al-Si-Cu-Fe aluminum alloy.

3. The Al-Si-Cu-Fe aluminum alloy with high Fe content according to claim 2, characterized in that, The Fe mass percentage is 0.5% to 0.8%, and the mass of recycled aluminum accounts for 70% to 90% of the mass of the Al-Si-Cu-Fe aluminum alloy.

4. The Al-Si-Cu-Fe aluminum alloy with high Fe content according to claim 2, characterized in that, The mass percentage of Fe is 0.8% to 1.0%.

5. The Al-Si-Cu-Fe aluminum alloy with high Fe content according to claim 4, characterized in that, The recycled aluminum material accounts for 90% to 100% of the mass of the Al-Si-Cu-Fe aluminum alloy.

6. The Al-Si-Cu-Fe aluminum alloy with high Fe content according to claim 1, characterized in that, The aluminum alloy consists of the following components by mass percentage Composition: Si: 7%–10%; Cu: 0.2%–1.3%; Fe: 0.2%~0.8%; Mg: 0.15% ~ 0.4%; Mn: 0.2% ~ 1.0%; Cr: 0.1% ~ 0.5%; Ni: 0.03% ~ 0.07%; Nb: 0.03% ~ 0.07%; RE: 0.05% ~ 0.15%; Ti: 0.08% ~ 0.2%; Sr: 0.008%~0.02%; the remainder is aluminum.

7. A method for preparing a high-Fe-content Al-Si-Cu-Fe aluminum alloy according to any one of claims 1-6, characterized in that, The method includes the following steps: (1) After preheating the pretreated recycled aluminum material and other aluminum materials, add them to the melting furnace and heat them to 740℃~750℃ to melt them and obtain the basic aluminum liquid; (2) According to the raw material ratio, add preheated Al-Si and Al-Cu master alloys, 75% to 77% manganese agent and 74% to 76% chromium agent to aluminum liquid at 740℃ to 750℃, stir manually for 10 to 15 minutes, and then keep at 740℃ to 750℃ for 15 to 20 minutes; then add Al-Ti, Al-Ni, Al-Nb master alloys and RE to aluminum liquid, stir manually for 10 to 15 minutes, and then take a sample for chemical composition detection; (3) After the alloy chemical composition is qualified, the refining agent is evenly sprayed into the aluminum liquid at 740℃~750℃ and refined for 10 minutes~15 minutes. After refining, it is left to stand for 15 minutes~20 minutes to allow the refining agent to fully react and float. The slag formed on the surface of the aluminum liquid is removed. The temperature of the aluminum liquid is reduced to 720℃~730℃, and inert gas is introduced into the aluminum liquid for degassing treatment for 10 minutes~15 minutes. After degassing, the surface slag is removed. Preheated pure magnesium ingots and Al-Sr master alloy are added to the aluminum liquid. The frequency of electromagnetic stirring is 20Hz~30Hz. After electromagnetic stirring for 10 minutes~15 minutes, it is left to stand for 15 minutes~20 minutes. The surface slag is removed and samples are taken to test the chemical composition. (4) Cool the aluminum liquid from step (3) to 680℃~700℃, and then use the die casting machine to perform high pressure casting to form the aluminum liquid in the ladle for 15s~30s. The die casting product of Al-Si-Cu-Fe aluminum alloy with high Fe content as described in any one of claims 1-6 is obtained.

8. The method for preparing the high Fe content Al-Si-Cu-Fe aluminum alloy according to claim 7, characterized in that, The preparation method further includes step (5), which involves coating the die-cast product of the high Fe content Al-Si-Cu-Fe aluminum alloy, including painting and / or powder coating and subsequent baking. The painting baking is carried out at 150℃~160℃ for 35 minutes to 50 minutes; the powder coating baking is carried out at 170℃~180℃ for 35 minutes to 50 minutes.

9. The method for preparing the high Fe content Al-Si-Cu-Fe aluminum alloy according to claim 8, characterized in that, In step (4), the ultrasonic stirring frequency is 20KHz~25KHz, the power is 2000W~3000W, the casting process is vacuum die casting, the vacuum pressure in the cavity is less than 100mbar, the die casting temperature is 680℃~700℃, and the mold temperature is 150℃~200℃; between steps (4) and (5) of the preparation method, there is also a simple aging treatment, which is to keep the temperature at 160℃~200℃ for 60 minutes~180 minutes.

10. The application of a high-Fe-content Al-Si-Cu-Fe aluminum alloy according to any one of claims 1-6 in load-bearing components.

Images