High-toughness die-cast aluminum alloy with chromium element, and preparation method and product thereof

Abstract

The application discloses a high-toughness die-casting aluminum alloy with a chromium element and a preparation method and product thereof, and belongs to the technical field of aluminum alloys. The aluminum alloy comprises the following components in percentage by mass: 7.0-10.0 wt.% of silicon, 0.05-0.4 wt.% of magnesium, 0.3-0.7 wt.% of manganese, 0.01-0.2 wt.% of titanium, 0.015-0.03 wt.% of strontium, 0.01-0.08 wt.% of vanadium, not more than 0.07 wt.% of chromium, and other components being aluminum and inevitable impurity elements. The application further discloses a preparation method and product of the aluminum alloy. The application provides a high-toughness die-casting aluminum alloy with a chromium element and a preparation method and product thereof. The aluminum alloy not only has high strength and high toughness in a cast state, but also has good fluidity and a good solidification range in a die-casting process, thereby smoothly filling a mold cavity under pressure driving, and shortening the forming time of molten aluminum in the mold. The aluminum alloy can not only guarantee the preparation quality of the aluminum alloy die casting, but also guarantee the service life of the mold.

Description

Technical Field

[0001] This invention belongs to the field of aluminum alloy technology, specifically relating to a high-toughness die-cast aluminum alloy containing chromium, its preparation method, and the product thereof. Background Technology

[0002] Aluminum and aluminum alloys possess characteristics such as low density, high specific strength, good plasticity, excellent mechanical properties, low coefficient of thermal expansion, good corrosion resistance, excellent electrical and thermal conductivity, ease of processing, and recyclability. They are widely used in aerospace, automotive, machinery manufacturing, shipbuilding, chemical industry, and packaging, becoming one of the most widely used non-ferrous metal materials in modern industry (especially the automotive industry), and are also a green, environmentally friendly, and sustainable non-ferrous metal material. With the development of the automotive manufacturing industry, higher performance requirements are being placed on aluminum alloy materials. Developing new aluminum alloys with high strength, high plasticity, high toughness, and good processing and manufacturing properties is of significant research importance.

[0003] In existing technologies, aluminum alloys are gradually increasing their proportion in automotive parts due to their lightweight advantages. This has led to the concept of integrated die casting, which combines numerous parts into one large component. Integrated die casting can combine more than 70 parts into 1-2 large parts, reducing stamping processes and lowering manufacturing costs. However, large castings present challenges in heat treatment, such as low efficiency, high energy consumption, and susceptibility to deformation. Therefore, heat-treatment-free materials with high strength and toughness in the as-cast state are needed to enable integrated die casting to eliminate the need for heat treatment processes.

[0004] Currently, the main heat-free material used in mass production is Alcoa C611. While C611 has a simple elemental composition and good stability, it suffers from relatively low strength. This makes aluminum alloy products made from this material unsuitable for components requiring high strength. Furthermore, the low silicon content of Alcoa C611 results in it being far from its eutectic point and having a wide solidification range, leading to poor fluidity of the molten aluminum. In actual die-casting processes, to ensure the quality of the finished parts, it is necessary to increase the temperature of the molten aluminum and extend the solidification time in the mold cavity. However, the prolonged residence of the high-temperature molten aluminum in the mold cavity negatively impacts the lifespan of the die-casting mold.

[0005] A key characteristic of Alcoa's C611 aluminum alloy is the absence of specific strengthening elements. In contrast, high-strength, high-toughness aluminum alloys with specific strengthening elements typically employ a combination of two to three elements. For example, Rheinmetall's Castasil 37 aluminum alloy uses Mo and Zr as its specific strengthening elements; Shanghai Jiao Tong University's Peng Liming team's JDA1b aluminum alloy uses V and RE (rare earth elements); and Tsinghua University's Xiong Shoumei team's THAS-2 aluminum alloy uses V and Zr (both with a content greater than 0.1 wt.%). Summary of the Invention

[0006] To address one or more of the aforementioned deficiencies or improvement needs in existing technologies, this invention provides a high-toughness die-cast aluminum alloy containing chromium, its preparation method, and the resulting product. Through the strengthening effect of trace amounts of V and Cr (both less than 0.1 wt.%), it achieves high strength and high toughness mechanical properties in the as-cast state. During die casting, it exhibits good fluidity and a good solidification range, allowing for smooth filling of the mold cavity under pressure and shortening the forming time of molten aluminum in the mold. This not only ensures the quality of the die-cast aluminum alloy parts but also extends the service life of the mold.

[0007] To achieve the above objectives, the present invention provides a high-toughness die-cast aluminum alloy containing chromium, wherein the aluminum alloy comprises the following components in the following mass percentages: 7.0–10.0 wt.% silicon, 0.05–0.4 wt.% magnesium, 0.3–0.7 wt.% manganese, 0.01–0.2 wt.% titanium, 0.015–0.03 wt.% strontium, 0.01–0.08 wt.% vanadium, not more than 0.07 wt.% chromium, and the remainder being aluminum and unavoidable impurity elements.

[0008] As a further preferred embodiment of the present invention, the unavoidable impurity elements include copper, iron, zinc, and zirconium, wherein the content of iron is not greater than 0.2 wt.%, and the content of each of the other elements is not greater than 0.05 wt.%, and the total content is not greater than 0.3 wt.%.

[0009] As a further preferred embodiment of the present invention, the aluminum alloy comprises the following components in the following mass percentages: 7.0 to 10.0 wt.% silicon, 0.05 to 0.4 wt.% magnesium, 0.3 to 0.7 wt.% manganese, 0.01 to 0.2 wt.% titanium, 0.015 to 0.03 wt.% strontium, 0.01 to 0.08 wt.% vanadium, 0.07 wt.% chromium, with the remainder being aluminum and unavoidable impurity elements.

[0010] As a further preferred embodiment of the present invention, the aluminum alloy comprises the following components in the following mass percentages: 7.6 to 9.5 wt.% silicon, 0.05 to 0.4 wt.% magnesium, 0.3 to 0.7 wt.% manganese, 0.01 to 0.2 wt.% titanium, 0.015 to 0.03 wt.% strontium, 0.01 to 0.08 wt.% vanadium, 0.02 wt.% chromium, with the remainder being aluminum and unavoidable impurity elements.

[0011] In addition, the present invention also provides a method for preparing a high-toughness die-cast aluminum alloy containing chromium, which is used to prepare the above-mentioned high-toughness die-cast aluminum alloy containing chromium, including the following steps: S1, weighing aluminum raw materials, silicon raw materials, magnesium raw materials, Al-Mn master alloy, Al-Ti master alloy, Al-V master alloy, Al-Cr master alloy, and Al-Sr master alloy according to the weight ratio.

[0012] S2. The weighed metal raw materials are added to the smelting furnace in batches to obtain molten aluminum liquid;

[0013] S3. After all the metal in the molten aluminum has melted, let the molten aluminum stand and analyze whether its chemical composition meets the requirements; if yes, proceed to step S5; otherwise, proceed to step S4.

[0014] S4. Determine the composition adjustment plan and materials based on the analysis of the chemical composition, and then proceed to step S2;

[0015] S5. The molten aluminum liquid is preliminarily refined, and the preliminarily refined molten aluminum liquid is injected into a transfer bag;

[0016] S6. The molten aluminum liquid that has been initially refined in the transfer package is subjected to secondary refining, and powdered Al-Ti-B master alloy is added to obtain refined aluminum liquid;

[0017] S7. Perform quality testing on the refined aluminum liquid to determine whether the refined aluminum liquid meets the quality requirements; if yes, proceed to step S9; otherwise, proceed to step S8.

[0018] S8. Determine the quality adjustment plan and materials based on the quality inspection, and then proceed to step S2;

[0019] S9. The refined aluminum liquid is injected into a die-casting machine for die casting to obtain a high-toughness die-cast aluminum alloy product with chromium.

[0020] As a further preferred embodiment of the present invention, S2 includes the following steps:

[0021] S21. The aluminum raw material is added to the melting furnace, and then the temperature in the melting furnace is raised to 680°C and maintained until the aluminum raw material is completely melted.

[0022] S22. The temperature in the melting furnace is raised to 720℃~750℃, and then silicon raw materials, Al-Mn master alloy, Al-V master alloy, Al-Zr master alloy, and Al-Sr master alloy are added, and the temperature in the melting furnace is maintained until the master alloys and silicon raw materials are completely melted.

[0023] S23. Reduce the temperature of the smelting furnace to 690℃~720℃, then press the magnesium raw material into the melt and maintain the temperature in the smelting furnace until the magnesium raw material is completely melted.

[0024] As a further preferred embodiment of the present invention, the aluminum raw material is one or more of pure aluminum or aluminum ingots for remelting with a quality of not less than Al99.80, and / or the silicon raw material is one or more of pure silicon or industrial silicon with a quality of not less than Si4410.

[0025] As a further preferred embodiment of the present invention, the quality detection in S2 includes one or more of chemical composition detection, density detection, and slag content detection.

[0026] As a further preferred embodiment of the present invention, in step S9, the refined aluminum liquid in the transfer bag is transferred into a heat-preserving furnace located on one side of the die-casting machine for heat preservation.

[0027] In addition, the present invention also discloses a high-toughness die-cast aluminum alloy product containing chromium, wherein the aluminum alloy product has the high-toughness die-cast aluminum alloy containing chromium described above.

[0028] Or the aluminum alloy product described above is a high-toughness die-cast aluminum alloy with chromium element prepared by the above-described method for preparing high-toughness die-cast aluminum alloy with chromium element.

[0029] Or at least a portion of the aluminum alloy product is obtained by reprocessing the high-toughness die-cast aluminum alloy containing chromium described above;

[0030] Alternatively, at least a portion of the aluminum alloy product may be obtained by further processing a high-toughness die-cast aluminum alloy containing chromium prepared by the above-described method for preparing high-toughness die-cast aluminum alloy containing chromium.

[0031] The aforementioned technical features can be combined with each other as long as they do not conflict with each other.

[0032] In summary, the beneficial effects of the above-described technical solutions conceived by this invention compared with the prior art include:

[0033] (1) This invention provides a high-toughness die-cast aluminum alloy containing chromium. By using 7.0–10.0 wt.% silicon, the molten aluminum is ensured to have excellent fluidity, while the aluminum alloy material exhibits better elongation. This ensures that the molten aluminum alloy can quickly, smoothly, and accurately fill the die-casting machine cavity, thereby guaranteeing the forming quality of the die-cast parts. The requirements for demolding and high toughness of the aluminum alloy castings are balanced by reducing the iron content and correspondingly increasing the manganese content. Furthermore, to improve the yield strength of the aluminum alloy material, magnesium is added at a mass percentage of 0.05–0.4 wt.%; simultaneously, vanadium is added at a mass percentage of 0.01–0.08 wt.% to promote element nucleation and refine grain size. Additionally, by adding no more than 0.07 wt.% chromium, trace amounts of Al are formed. 13 Cr4Si4 promotes crystallization. Furthermore, appropriate amounts of strontium are added to improve the morphology of the eutectic silicon. Aluminum alloy products made from this alloy exhibit as-cast mechanical properties with tensile strength of 250–280 MPa, yield strength of 115–135 MPa, and elongation of 14–19%, demonstrating leading toughness among AlSi-based cast aluminum alloys.

[0034] (2) The present invention provides a high-toughness die-cast aluminum alloy with chromium element. By adjusting the content of iron, manganese and chromium in the aluminum alloy material, the slag-forming factor of the aluminum alloy material is always kept in the range of slightly greater than 0.2wt.%, and the aluminum liquid is used in time within 8 hours. This not only avoids the deposition of slag due to excessive slag-forming factor, but also forms intermediate nuclei to promote formation. When the chromium element is kept in trace amounts, the toughness of the material can also be optimized. Thus, while reducing the cost of die castings, the applicability of aluminum alloy die castings can be significantly improved.

[0035] (3) The present invention provides a high-toughness die-cast aluminum alloy with chromium. Its aluminum alloy composition is simple, with only vanadium and chromium as special strengthening elements. It achieves a tensile strength of 250 MPa, a yield strength of 115 MPa, and an elongation of 12% in terms of mechanical properties. Furthermore, while meeting the performance requirements of structural components, its performance test results from samples taken at different locations are stable. Therefore, it can also be used for die-casting shock-absorbing towers, longitudinal beams, and other traditional high-strength and tough structural components. Moreover, compared to other high-strength and toughness aluminum alloys in China, it uses fewer strengthening elements, resulting in lower production costs. It also reduces the heat treatment process and deformation during heat treatment, and can be quickly implemented on existing die-casting production lines without significant investment.

[0036] (4) The high-toughness die-cast aluminum alloy containing chromium in this invention, its preparation method, and the product thereof have excellent material properties, convenient preparation process, and wide applicability. By adding appropriate amounts of vanadium and chromium to the aluminum alloy material, the aluminum alloy material, during the solidification process, not only will not produce obvious slag in the die-casting parts due to slag-forming factors, but it can also promote the formation of fine Al. 13 Cr4Si4, thus promoting nucleation during the die-casting process. Furthermore, the addition of trace amounts of chromium can combine with Fe and Mn to form Al(FeMnCr)Si compounds, reducing the adverse effects of acicular iron phase fragmentation on the specific microstructure and enhancing the toughness of aluminum alloy die-castings. This significantly reduces the manufacturing cost of aluminum alloy materials while ensuring that aluminum alloy die-castings possess excellent casting performance and high strength and toughness, meeting the mechanical performance requirements of automotive chassis structures. It enables one-time die-casting of the rear floor, consolidating numerous parts into one, reducing stamping processes, improving manufacturing efficiency, and reducing the weight of the rear floor to meet the automotive industry's lightweighting requirements of replacing steel with aluminum, demonstrating excellent economic benefits and promotional value. Attached Figure Description

[0037] Figure 1 This is a flowchart of the method for preparing high-toughness die-cast aluminum alloy with chromium element according to the present invention. Detailed Implementation

[0038] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0039] The high-toughness die-cast aluminum alloy containing chromium in the preferred embodiment of this application, its preparation method, and the product not only possess high strength and high toughness mechanical properties in the as-cast state, but also have good fluidity and a good solidification range during the die-casting process. This allows it to smoothly fill the mold cavity under pressure and shorten the forming time of molten aluminum in the mold. This not only ensures the preparation quality of the aluminum alloy die-casting parts, but also ensures the service life of the mold.

[0040] Specifically, in the preferred embodiment of this application, the high-toughness die-cast aluminum alloy containing chromium comprises the following components by mass percentage: 7.0–10.0 wt.% silicon, 0.05–0.4 wt.% magnesium, 0.3–0.7 wt.% manganese, 0.01–0.2 wt.% titanium, 0.015–0.03 wt.% strontium, 0.01–0.08 wt.% vanadium, and no more than 0.07 wt.% chromium, with the remainder being aluminum and unavoidable impurity elements. Aluminum alloy products prepared using this alloy exhibit as-cast mechanical properties reaching a tensile strength of 250–280 MPa, a yield strength of 115–135 MPa, and an elongation of 14–19%, demonstrating leading toughness performance among AlSi-based cast aluminum alloys.

[0041] More specifically, in the aforementioned high-toughness die-cast aluminum alloy containing chromium, the weight percentage of silicon is controlled within the range of 7.0–10.0 wt.%, ensuring excellent fluidity of the molten aluminum and enabling the alloy to possess better elongation. In practical applications, this ensures that the molten aluminum alloy can quickly, smoothly, and accurately fill the die-casting machine cavity, thereby guaranteeing the molding quality of the die-cast parts. To facilitate easy demolding of the die-cast parts, 0.3–0.7 wt.% manganese is added to the aluminum alloy to form a release agent after die-casting, facilitating demolding.

[0042] Meanwhile, to ensure the yield strength of the aluminum alloy, 0.05–0.4 wt.% magnesium is added to the aluminum alloy material, ensuring that the yield strength of the aluminum alloy material can be stably maintained above 115 MPa in any die-cast product. This ensures that the aluminum alloy material has a wider range of applications and significantly enhances its economic value. Elongation is also one of the key indicators of aluminum alloy materials. The aluminum alloy material contains an Al-Ti-B master alloy, 0.01–0.08 wt.% vanadium, and no more than 0.07 wt.% chromium. The Al-Ti-B master alloy refines the alloy crystal structure, while the 0.01–0.08 wt.% vanadium promotes the formation of nuclei in the aluminum alloy melt during solidification as Al3V particles. Combined with the no more than 0.07 wt.% chromium added to the aluminum alloy material, proprecipitates can form in the aluminum alloy melt during solidification, which promotes the crystallization of the aluminum alloy melt. Furthermore, in order to improve the morphology of eutectic silicon in aluminum alloys, 0.015 to 0.03 wt.% of strontium was added to the aluminum alloys, thereby improving the performance of the die-cast aluminum alloy products.

[0043] Furthermore, in the preferred embodiment of this application, unavoidable impurity elements include copper, iron, zinc, and zirconium. The content of iron is no greater than 0.2 wt.%, and the content of each of the other elements is no greater than 0.05 wt.%, with a total content of no greater than 0.3 wt.%. Since the atomic mass of iron, manganese, and chromium is much larger than that of aluminum, slag will form in the smelting furnace during the aluminum alloy smelting process. In the die-cast aluminum alloy molten metal, the element mass fraction SF (slag-forming factor) is generally controlled to satisfy: SF = Fe + 2Mn + 3Cr, 0.3 wt.% > SF > 0.2 wt.%.

[0044] Further preferably, in a preferred embodiment of this application, the aluminum alloy comprises the following components in weight percentages: 7.0–10.0 wt.% silicon, 0.05–0.4 wt.% magnesium, 0.3–0.7 wt.% manganese, 0.01–0.2 wt.% titanium, 0.015–0.03 wt.% strontium, 0.01–0.08 wt.% vanadium, 0.07 wt.% chromium, with the remainder being aluminum and unavoidable impurity elements. Preferably, the aluminum alloy contains 0.1 wt.% iron, 0.05 wt.% manganese, and 0.07 wt.% chromium, such that the slag-forming factor of the aluminum alloy is slightly greater than 0.2 wt.%.

[0045] Preferably, in this preferred embodiment, the molten aluminum is used within 8 hours, thereby not only avoiding the formation of significant deposited slag, but also forming fine Al particles. 13 The Cr4Si4 mesophase promotes nucleation without reducing the material's toughness.

[0046] Further, in another preferred embodiment of this application, the aluminum alloy comprises the following components in the indicated mass percentages: 7.6–9.5 wt.% silicon, 0.05–0.4 wt.% magnesium, 0.3–0.7 wt.% manganese, 0.01–0.2 wt.% titanium, 0.015–0.03 wt.% strontium, 0.01–0.08 wt.% vanadium, 0.02 wt.% chromium, with the remainder being aluminum and unavoidable impurity elements. Preferably, the aluminum alloy contains 0.1 wt.% Fe, 0.05 wt.% manganese, and a trace amount of 0.02 wt.% chromium, which not only enables the formation of fine Al... 13 The Cr4Si4 intermediate phase promotes nucleation and can also combine with Fe elements to form Al(FeMnCr)Si compounds, reducing the acicular iron phase compounds and thus optimizing the toughness of aluminum alloy materials.

[0047] Furthermore, such as Figure 1 As shown in the figure, this application also discloses a method for preparing a high-toughness die-cast aluminum alloy containing chromium, which includes the following steps:

[0048] S1. Weigh aluminum raw materials, silicon raw materials, magnesium raw materials, Al-Mn master alloy, Al-Ti master alloy, Al-V master alloy, Al-Cr master alloy, and Al-Sr master alloy according to the weight ratio.

[0049] Preferably, the aluminum raw material is one or more of pure aluminum (pure aluminum ingots or pure aluminum powder) or remelting aluminum ingots with a quality of not less than Al99.80, and / or the silicon raw material is one or more of pure silicon or industrial silicon with a quality of not less than Si4410. More preferably, the magnesium raw material is pure magnesium ingot.

[0050] S2. The weighed metal raw materials are added to the smelting furnace in batches to obtain molten aluminum liquid;

[0051] Preferably, S2 includes the following steps:

[0052] S21. Add aluminum raw material to the melting furnace, then raise the temperature in the melting furnace to 680°C and maintain the temperature in the melting furnace until all the aluminum raw material is melted.

[0053] S22. Raise the temperature in the melting furnace to 720℃~750℃, then add silicon raw materials, Al-Mn master alloy, Al-Ti master alloy, Al-V master alloy, Al-Cr master alloy, and Al-Sr master alloy, and maintain the temperature in the melting furnace until the master alloys and silicon raw materials are completely melted.

[0054] S23. Reduce the temperature of the smelting furnace to 690℃~720℃, then press the magnesium raw material into the melt and maintain the temperature in the smelting furnace until the pure magnesium ingot is completely melted.

[0055] S3. After all the metal in the molten aluminum has melted, let the molten aluminum stand and analyze whether its chemical composition meets the requirements; if yes, proceed to step S5; otherwise, proceed to step S4.

[0056] S4. Determine the composition adjustment plan and materials based on the analysis of chemical composition, and then proceed to step S2;

[0057] S5. Perform preliminary refining on the molten aluminum and inject the preliminary refined molten aluminum into the transfer bag;

[0058] S6. The preliminarily refined molten aluminum in the transfer package is further refined, and an Al-Ti-B master alloy is added to obtain refined aluminum liquid.

[0059] S7. Perform quality inspection on the refined aluminum liquid to determine whether the refined aluminum liquid meets the quality requirements; if yes, proceed to step S9; otherwise, proceed to step S8.

[0060] Preferably, the quality test includes chemical composition testing, density testing, and slag content testing, wherein the K modulus value is not greater than 0 / 20, that is, the slag content is zero.

[0061] S8. Determine the quality adjustment plan and materials based on the quality inspection, and then proceed to step S2;

[0062] S9. The refined aluminum liquid is injected into the die casting machine for die casting to obtain a high-toughness die-cast aluminum alloy product with chromium.

[0063] Preferably, the refined aluminum liquid in the transfer package is transferred to a holding furnace located on one side of the die-casting machine for heat preservation, and the temperature in the holding furnace is maintained between 690°C and 720°C.

[0064] More preferably, the ingate speed is 3 m / s, the casting pressure is 80 MPa, the release agent ratio is 1:80, the mold temperature is 180-230℃, and the vacuum degree is above 30 mbar.

[0065] Furthermore, in a preferred embodiment of this application, the preliminary refining and / or secondary refining are carried out by introducing gas and adding solid refining agents. Preferably, the gas is argon or nitrogen.

[0066] Further, in a preferred embodiment of this application, the preliminary refining specifically includes the following steps: introducing gas at a flow rate of 16-22 L / min and adding 0.1-0.3% solid refining agent by weight of the melt, with a gas pressure of 0.2-0.4 MPa, and a slag and gas removal time of 5-30 min, followed by removing surface slag.

[0067] Accordingly, in the preferred embodiment of this application, the secondary refining specifically includes the following steps: after removing the slag from the surface of the molten aluminum, add 5 kg / ton of Al-Ti-B refining agent, press it into the melt and stir to dissolve it. Then, introduce nitrogen gas and 150-200 g / ton of solid refining agent at a flow rate of 25-30 L / min, and then perform rotary refining for 5 minutes to remove slag and gas at a speed of 450-550 r / min, followed by slag removal.

[0068] Furthermore, in a preferred embodiment of this application, a high-toughness die-cast aluminum alloy product containing chromium is also disclosed. Specifically, the high-toughness die-cast aluminum alloy product containing chromium has the aforementioned high-toughness die-cast aluminum alloy containing chromium.

[0069] Or the high-toughness die-cast aluminum alloy product containing chromium has the high-toughness die-cast aluminum alloy containing chromium prepared by the above-mentioned method for preparing high-toughness die-cast aluminum alloy containing chromium.

[0070] Alternatively, at least a portion of the high-toughness die-cast aluminum alloy product containing chromium is obtained by reprocessing the aforementioned high-toughness die-cast aluminum alloy containing chromium.

[0071] Alternatively, at least a portion of the high-toughness die-cast aluminum alloy product containing chromium is obtained by further processing a high-toughness die-cast aluminum alloy containing chromium prepared by the above-mentioned method for preparing high-toughness die-cast aluminum alloy containing chromium.

[0072] More specifically, in the preferred embodiment of this application, the aluminum alloy passed small-batch trial production of an integrated front compartment. In areas with good filling, its performance meets the performance requirements of automotive chassis structural components and can be applied to the production of integrated rear floor, front engine compartment, battery tray, and other structural components. Furthermore, it passed performance verification of the integrated die-cast front compartment parts. In areas with good filling, the sampled yield strength was 115–135 MPa, tensile strength was 255–270 MPa, and elongation was 14–19%. While meeting structural requirements, the performance test results from samples taken at different locations remained stable, making it suitable for structural components with high requirements for collision energy absorption performance.

[0073] The present invention will now be described with reference to specific embodiments. It should be noted that these embodiments are merely descriptive and do not limit the present invention in any way.

[0074] Example 1

[0075] The high-toughness die-cast aluminum alloy containing chromium has the following components by weight percentage: silicon: 8.5 wt.%, magnesium: 0.25 wt.%, manganese: 0.5 wt.%, titanium: 0.03 wt.%, strontium: 0.02 wt.%, vanadium: 0.02 wt.%, chromium: 0.07 wt.%, iron not more than 0.2 wt.%, and other unavoidable impurities other than iron, each not more than 0.05 wt.%, totaling not more than 0.25 wt.%, with the remainder being aluminum.

[0076] The preparation method of this high-toughness die-cast aluminum alloy containing chromium includes the following steps:

[0077] S1. Weigh out 15 kg each of Al99.80 aluminum ingot, Si4410 industrial silicon, pure magnesium ingot, Al-Mn master alloy, Al-Ti master alloy, Al-V master alloy, Al-Cr master alloy, Al-Sr master alloy and A-Ti-B refining agent according to the weight ratio, for a total of 3000 kg.

[0078] S2. The weighed metal raw materials are added to the smelting furnace in batches to obtain molten aluminum liquid;

[0079] S2 includes the following steps:

[0080] S21. Add pure aluminum ingots to the melting furnace, then raise the temperature in the melting furnace to 680°C and maintain the temperature in the melting furnace until all the pure aluminum ingots are melted.

[0081] S22. Raise the temperature in the melting furnace to 720℃~750℃, then add Si4410 industrial silicon, Al-Mn master alloy, Al-Ti master alloy, Al-V master alloy, Al-Cr master alloy, and Al-Sr master alloy, and maintain the temperature in the melting furnace until the master alloy and Si4410 industrial silicon are completely melted.

[0082] S23. Reduce the temperature of the smelting furnace to 720°C, then press the pure magnesium ingot into the melt and maintain the temperature in the smelting furnace until the pure magnesium ingot is completely melted.

[0083] S3. After all the metal in the molten aluminum melts, maintain the temperature between 700℃ and 730℃ and let the molten aluminum melt stand for 10 minutes, and analyze whether its chemical composition meets the requirements; if yes, proceed to step S5; otherwise, proceed to step S4.

[0084] S4. Determine the composition adjustment plan and materials based on the analysis of chemical composition, and then proceed to step S2;

[0085] S5. Nitrogen gas is introduced into the molten aluminum liquid at a pressure of 0.4 MPa and 9 kg of solid refining agent is added. The refining is carried out for 10 minutes to remove slag and gas from the molten aluminum liquid. Then, the surface slag is removed to complete the preliminary refining. The preliminary refined molten aluminum liquid is then injected into a 1.5-ton capacity transfer bag.

[0086] S6. After removing the slag from the surface of the molten aluminum, add 15kg of Al-Ti-B refining agent, press it into the melt and stir for 1 minute to melt it. Then, introduce nitrogen and 150g of solid refining agent at a pressure of 0.4MPa and perform rotary refining for 5 minutes to remove slag and gas. After that, remove the slag to obtain refined molten aluminum.

[0087] S7. Perform quality inspection on the refined aluminum liquid to determine whether the refined aluminum liquid meets the quality requirements; if yes, proceed to step S9; otherwise, proceed to step S8.

[0088] S8. Determine the quality adjustment plan and materials based on the quality inspection, and then proceed to step S2;

[0089] S9. Under the following conditions, die casting is carried out: aluminum liquid temperature 680~700℃, casting pressure 75MPa, release agent ratio 1:80, mold temperature 200℃, vacuum degree 30mbar, and ingate speed 87m / s. The die casting mold has two cavities and produces a die-cast plate of high toughness die-cast aluminum alloy with chromium element with a size of 200*210mm.

[0090] Example 2

[0091] The weight percentages of the components in a high-toughness die-cast aluminum alloy of this embodiment are as follows: silicon: 8.0 wt.%, magnesium: 0.25 wt.%, manganese: 0.5 wt.%, titanium: 0.03%, strontium: 0.02 wt.%, vanadium: 0.02 wt.%, chromium: 0.02 wt.%, iron not more than 0.2 wt.%, other unavoidable impurities other than iron not more than 0.05 wt.% of each individual element, and not more than 0.25 wt.% in total, with the remainder being aluminum.

[0092] The preparation method in this embodiment is the same as that in Example 1, except that the ingredients are different.

[0093] Example 3

[0094] The weight percentages of the components in a high-toughness die-cast aluminum alloy of this embodiment are as follows: silicon: 7.0 wt.%, magnesium: 0.05 wt.%, manganese: 0.3 wt.%, titanium: 0.01%, strontium: 0.015 wt.%, vanadium: 0.01 wt.%, iron not more than 0.2 wt.%, other unavoidable impurities other than iron not more than 0.05 wt.% of each individual element, and not more than 0.25 wt.% in total, with the remainder being aluminum.

[0095] The preparation method in this embodiment is the same as that in Example 1, except that the ingredients are different.

[0096] Example 4

[0097] The weight percentages of the components in this embodiment of a high-toughness die-cast aluminum alloy are as follows: silicon: 10.0 wt.%, magnesium: 0.4 wt.%, manganese: 0.7 wt.%, titanium: 0.2%, strontium: 0.03 wt.%, vanadium: 0.08 wt.%, chromium: 0.07 wt.%, iron not more than 0.2 wt.%, and other unavoidable impurities other than iron, each not more than 0.05 wt.%, totaling not more than 0.25 wt.%, with the remainder being aluminum.

[0098] The preparation method in this embodiment is the same as that in Example 1, except that the ingredients are different.

[0099] Example 5

[0100] The weight percentages of the components in this embodiment of a high-toughness die-cast aluminum alloy are as follows: silicon: 9.0 wt.%, magnesium: 0.25 wt.%, manganese: 0.5 wt.%, titanium: 0.10%, strontium: 0.025 wt.%, vanadium: 0.04 wt.%, chromium: 0.05 wt.%, iron: 0.08 wt.%, and other unavoidable impurities other than iron, with each individual element not exceeding 0.05 wt.% and the total not exceeding 0.25 wt.%, with the remainder being aluminum.

[0101] The preparation method in this embodiment is the same as that in Example 1, except that the ingredients are different.

[0102] Example 6

[0103] The weight percentages of the components in this embodiment of a high-toughness die-cast aluminum alloy are as follows: silicon: 9.0 wt.%, magnesium: 0.30 wt.%, manganese: 0.6 wt.%, titanium: 0.05%, strontium: 0.025 wt.%, vanadium: 0.06 wt.%, chromium: 0.03 wt.%, iron: 0.20 wt.%, and other unavoidable impurities other than iron, with each individual element not exceeding 0.05 wt.% and the total not exceeding 0.25 wt.%, with the remainder being aluminum.

[0104] The preparation method in this embodiment is the same as that in Example 1, except that the ingredients are different.

[0105] Example 7

[0106] The weight percentages of the components in a high-toughness die-cast aluminum alloy of this embodiment are as follows: silicon: 9.0 wt.%, magnesium: 0.20 wt.%, manganese: 0.4 wt.%, titanium: 0.05%, strontium: 0.025 wt.%, vanadium: 0.04 wt.%, chromium: 0.03 wt.%, iron: 0.12 wt.%, copper: 0.05 wt.%, and other unavoidable impurities other than iron and copper, with each individual element not exceeding 0.05 wt.% and the total not exceeding 0.20 wt.%, with the remainder being aluminum.

[0107] The preparation method in this embodiment is the same as that in Example 1, except that the ingredients are different.

[0108] Example 8

[0109] The weight percentages of the components in a high-toughness die-cast aluminum alloy of this embodiment are as follows: silicon: 9.0 wt.%, magnesium: 0.20 wt.%, manganese: 0.3 wt.%, titanium: 0.05%, strontium: 0.025 wt.%, vanadium: 0.03 wt.%, chromium: 0.03 wt.%, iron: 0.10 wt.%, copper: 0.05 wt.%, zinc: 0.05 wt.%, and other unavoidable impurities other than iron, copper, and zinc, with each individual element not exceeding 0.05 wt.% and the total not exceeding 0.15 wt.%, with the remainder being aluminum.

[0110] The preparation method in this embodiment is the same as that in Example 1, except that the ingredients are different.

[0111] Example 9

[0112] The weight percentages of the components in this embodiment of a high-toughness die-cast aluminum alloy are as follows: silicon: 9.0 wt.%, magnesium: 0.25 wt.%, manganese: 0.3 wt.%, titanium: 0.05%, strontium: 0.025 wt.%, vanadium: 0.02 wt.%, chromium: 0.02 wt.%; iron: 0.10 wt.%, copper: 0.05 wt.%, zinc: 0.05 wt.%, zirconium: 0.05 wt.%, and other unavoidable impurities other than iron, copper, zinc, and zirconium, with each individual element not exceeding 0.05 wt.% and the total not exceeding 0.10 wt.%, with the remainder being aluminum.

[0113] The preparation method in this embodiment is the same as that in Example 1, except that the ingredients are different.

[0114] Example 10

[0115] The weight percentages of the components in this embodiment of a high-toughness die-cast aluminum alloy are as follows: silicon: 8.0 wt.%, magnesium: 0.25 wt.%, manganese: 0.3 wt.%, titanium: 0.05%, strontium: 0.025 wt.%, vanadium: 0.02 wt.%, chromium: 0.02 wt.%; iron: 0.10 wt.%, copper: 0.03 wt.%, zinc: 0.02 wt.%, zirconium: 0.02 wt.%, and other unavoidable impurities other than iron, copper, zinc, and zirconium, with each individual element not exceeding 0.05 wt.% and the total not exceeding 0.10 wt.%, with the remainder being aluminum.

[0116] The preparation method in this embodiment is the same as that in Example 1, except that the ingredients are different.

[0117] Example 11

[0118] The weight percentages of the components in this embodiment of a high-toughness die-cast aluminum alloy are as follows: silicon: 8.0 wt.%, magnesium: 0.25 wt.%, manganese: 0.3 wt.%, titanium: 0.05%, strontium: 0.025 wt.%, vanadium: 0.02 wt.%, chromium: 0.02 wt.%; iron: 0.10 wt.%, copper: 0.03 wt.%, zinc: 0.02 wt.%, zirconium: 0.02 wt.%, and other unavoidable impurities other than iron, copper, zinc, and zirconium, with each individual element not exceeding 0.05 wt.% and the total not exceeding 0.10 wt.%, with the remainder being aluminum.

[0119] The preparation method in this embodiment is the same as that in Example 1, except that the ingredients are different.

[0120] The obtained plate was placed in a heat treatment experimental furnace at 170℃ for 20 minutes and then air-cooled; then at 150℃ for 20 minutes and then air-cooled; then at 140℃ for 20 minutes and then air-cooled.

[0121] Example 12

[0122] The weight percentages of the components in this embodiment of a high-toughness die-cast aluminum alloy are as follows: silicon: 8.0 wt.%, magnesium: 0.25 wt.%, manganese: 0.3 wt.%, titanium: 0.05%, strontium: 0.025 wt.%, vanadium: 0.02 wt.%, chromium: 0.02 wt.%; iron: 0.10 wt.%, copper: 0.03 wt.%, zinc: 0.02 wt.%, zirconium: 0.02 wt.%, and other unavoidable impurities other than iron, copper, zinc, and zirconium, with each individual element not exceeding 0.05 wt.% and the total not exceeding 0.10 wt.%, with the remainder being aluminum.

[0123] The molten aluminum material is transferred to the machine-side holding furnace and then injected into a 7000T die-casting machine for die casting. After removing the gating system and slag bag, the weight of the casting body is 57kg.

[0124] Example 13

[0125] The flat plate of Example 2 was placed in a muffle oven and baked at 170°C for 20 minutes, cooled, and then kept at 150°C for 20 minutes, and then kept at 140°C for 20 minutes.

[0126] Comparative Example 1

[0127] The AlSi10MnMg aluminum alloy of this comparative example has the following weight percentages: silicon: 10.0 wt.%, magnesium: 0.3 wt.%, manganese: 0.5 wt.%, titanium: 0.07%, strontium: 0.02 wt.%, iron: 0.12 wt.%, and other unavoidable impurities, with each individual element not exceeding 0.05 wt.% and the total not exceeding 0.15 wt.%, with the remainder being aluminum.

[0128] The preparation method of this comparative example is the same as that of Example 1, except that the ingredients are different.

[0129] In Comparative Example 1, AlSi10MnMg is an EU aluminum alloy grade, which is a heat-treatable die-cast alloy disclosed in patent US6364970B1.

[0130] Comparative Example 2

[0131] The AlSi10MnMg aluminum alloy of this comparative example has the following weight percentages: silicon: 10.0 wt.%, magnesium: 0.4 wt.%, manganese: 0.6 wt.%, titanium: 0.07%, strontium: 0.02 wt.%, iron: 0.10 wt.%, copper: 0.03 wt.%, and other unavoidable impurities, with each individual element not exceeding 0.05 wt.% and the total not exceeding 0.15 wt.%, with the remainder being aluminum.

[0132] The preparation method of this comparative example is the same as that of Example 1, except that the ingredients are different.

[0133] Comparative Example 3

[0134] The weight percentages of the components in this comparative example of ADC12 aluminum alloy are as follows: silicon: 10.5 wt.%, copper: 2.5 wt.%, magnesium: 0.2 wt.%, iron: 1.0 wt.%, manganese: 0.4 wt.%, titanium: 0.05%, zinc: 0.5 wt.%, nickel: 0.05 wt.%, tin: 0.05 wt.%, lead: 0.05 wt.%. Other unavoidable impurities are present in quantities no greater than 0.05 wt.% for each individual element and no greater than 0.15 wt.% in total, with the remainder being aluminum.

[0135] The preparation method of this comparative example is the same as that of Example 1, except that the ingredients are different.

[0136] In Comparative Example 3, ADC12 is a Japanese grade, also known as No. 12 aluminum material. It is an Al-Si-Cu alloy and a type of die-cast aluminum alloy.

[0137] Table 1 Chemical composition (wt.%) of die-cast aluminum alloy in the examples

[0138]

[0139] Table 2. Chemical composition (wt.%) of comparative die-cast aluminum alloys

[0140]

[0141] Table 3 Properties of Die-cast Aluminum Alloys

[0142] Group Implementation Features Tensile strength / MPa Yield strength / MPa Elongation / % Example 1 The upper limit of Cr content in this invention 258.14 117.84 19.25 Example 2 Typical content of core elements in this invention 261.97 118.60 17.51 Example 3 Lower limit of core elements of this invention 257.74 118.29 17.30 Example 4 Upper limit of core elements of this invention 268.32 132.26 12.41 Example 5 This invention limits the lower limit of Fe content. 266.40 121.95 17.67 Example 6 This invention limits the upper limit of Fe content. 268.64 123.65 13.44 Example 7 The upper limit of Cu impurity content in this invention 267.88 119.33 14.76 Example 8 The upper limit of Cu and Zn impurity content in this invention 267.03 122.58 14.97 Example 9 The upper limit of Cu, Zn, and Zr impurity content in this invention 266.24 125.60 15.47 Example 10 Typical components of this invention in as-cast state 258.71 115.92 18.47 Example 11 Typical components of this invention in baked state 264.76 140.78 15.08 Example 12 This invention relates to a large aluminum alloy die-cast structural component. 264.50 136.38 9.95 Example 13 Baking test pieces of the present invention 268.15 145.71 16.11 Comparative Example 1 Silafont 36 / AlSi10MnMg 279.61 144.94 9.64. Comparative Example 2 Silafont 36 / AlSi10MnMg 283.49 152.13 8.29 Comparative Example 3 ADC12 343.60 185.58 3.22

[0143] According to the table above, the cast plates prepared with aluminum alloy materials in Examples 1 to 10 of this application can achieve a yield strength of 115-135 MPa, a tensile strength of 250-280 MPa, and an elongation of 14-19%. In particular, the elongation of the plate prepared with aluminum alloy material in Example 1 of this application can reach 19.25%. Meanwhile, in Examples 4 and 6 of this application, even with high contents of some core elements other than aluminum, the plates prepared with aluminum alloy materials still maintain a high elongation of 12%. Compared to the 5-10% elongation of plates prepared with Silafont 36 alloy using the same process, the plates prepared in any of the embodiments of this application have a significant advantage in elongation, resulting in die-cast parts prepared with the die-cast aluminum alloy materials in these embodiments having excellent impact energy absorption performance. This enables the fabrication of structural components with high impact energy absorption requirements, such as integrated die-cast fore-chambers.

[0144] Meanwhile, since most automotive parts need to be baked before they can be used, in Example 13 of this application, the baked test piece prepared using the aluminum alloy ratio disclosed in Example 13 has a yield strength of 130-150 MPa, a tensile strength of 260-275 MPa, and an elongation of 13-17% after tensile mechanical property testing. The yield strength of the baked test piece is significantly increased compared to the yield strength of the cast plate, while the elongation of the baked test piece remains at a high level.

[0145] This invention discloses a high-toughness die-cast aluminum alloy containing chromium, its preparation method, and the resulting product. The alloy exhibits excellent material properties, a convenient preparation process, and a wide range of applications. By adding appropriate amounts of vanadium and chromium to the aluminum alloy material, the solidification process not only avoids the formation of significant slag in the die-cast parts due to slag-forming factors, but also promotes the formation of fine Al particles. 13 Cr4Si4, thus promoting nucleation during the die-casting process. Furthermore, the addition of trace amounts of chromium can also combine with Fe to form Al(FeMnCr)Si compounds, reducing the acicular structure of the iron phase and optimizing the toughness of the aluminum alloy. This invention can significantly reduce the manufacturing cost of aluminum alloy materials while ensuring that the die-cast aluminum alloy parts possess good casting performance and high strength and toughness, meeting the mechanical performance requirements of automotive chassis structures. It enables one-time die-casting of the front compartment and rear floor, merging numerous parts into one, reducing stamping processes, improving manufacturing efficiency, and reducing the weight of the front compartment and rear floor to meet the automotive industry's lightweighting requirements of replacing steel with aluminum. It has excellent economic benefits and promotional value.

[0146] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A high-toughness die-cast aluminum alloy containing chromium, characterized in that, The aluminum alloy comprises the following components in the following mass percentages: 7.0~10.0 wt.% silicon, 0.05~0.4 wt.% magnesium, 0.3~0.7 wt.% manganese, 0.01~0.2 wt.% titanium, 0.015~0.03 wt.% strontium, 0.01~0.08 wt.% vanadium, not more than 0.07 wt.% chromium, and the remainder being aluminum and unavoidable impurity elements; The unavoidable impurity elements include copper, iron, zinc, and zirconium, with iron content not exceeding 0.2 wt.% and the remaining elements individually not exceeding 0.05 wt.%, totaling not exceeding 0.3 wt.%. Furthermore, the slag-forming factor SF satisfies: SF = Fe + 2Mn + 3Cr, 1.81 wt.% > SF > 0.6 wt.%; The molten aluminum alloy is used within 8 hours to form fine Al particles. 13 The Cr4Si4 mesophase promotes nucleation and avoids the formation of sedimentary slag; A method for preparing high-toughness die-cast aluminum alloys containing chromium, comprising the following steps: S1. Weigh aluminum raw materials, silicon raw materials, magnesium raw materials, Al-Mn master alloy, Al-Ti master alloy, Al-V master alloy, Al-Cr master alloy, and Al-Sr master alloy according to the weight ratio. S2. The weighed metal raw materials are added to the smelting furnace in batches to obtain molten aluminum liquid; S3. After all the metal in the molten aluminum has melted, let the molten aluminum stand and analyze whether its chemical composition meets the requirements; if yes, proceed to step S5; otherwise, proceed to step S4. S4. Determine the composition adjustment plan and materials based on the analysis of the chemical composition, and then proceed to step S2; S5. The molten aluminum liquid is preliminarily refined, and the preliminarily refined molten aluminum liquid is injected into a transfer bag; S6. The molten aluminum liquid that has been initially refined in the transfer package is subjected to secondary refining, and powdered Al-Ti-B master alloy is added to obtain refined aluminum liquid; S7. Perform quality testing on the refined aluminum liquid to determine whether the refined aluminum liquid meets the quality requirements; if yes, proceed to step S9; otherwise, proceed to step S8. S8. Determine the quality adjustment plan and materials based on the quality inspection, and then proceed to step S2; S9. The refined aluminum liquid is injected into a die-casting machine for die casting to obtain a high-toughness die-cast aluminum alloy product with chromium.

2. The high-toughness die-cast aluminum alloy containing chromium according to claim 1, wherein, The aluminum alloy comprises the following components in the following weight percentages: 7.0 to 10.0 wt.% silicon, 0.05 to 0.4 wt.% magnesium, 0.3 to 0.7 wt.% manganese, 0.01 to 0.2 wt.% titanium, 0.015 to 0.03 wt.% strontium, 0.01 to 0.08 wt.% vanadium, 0.07 wt.% chromium, with the remainder being aluminum and unavoidable impurity elements.

3. The high-toughness die-cast aluminum alloy containing chromium according to claim 1, wherein, The aluminum alloy comprises the following components in the following weight percentages: 7.6 to 9.5 wt.% silicon, 0.05 to 0.4 wt.% magnesium, 0.3 to 0.7 wt.% manganese, 0.01 to 0.2 wt.% titanium, 0.015 to 0.03 wt.% strontium, 0.01 to 0.08 wt.% vanadium, 0.02 wt.% chromium, with the remainder being aluminum and unavoidable impurity elements.

4. The high-toughness die-cast aluminum alloy containing chromium according to claim 1, wherein, S2 includes the following steps: S21. The aluminum raw material is added to the melting furnace, and then the temperature in the melting furnace is raised to 680°C and maintained until the aluminum raw material is completely melted. S22. The temperature in the melting furnace is raised to 720℃~750℃, and then silicon raw materials, Al-Mn master alloy, Al-Ti master alloy, Al-V master alloy, Al-Cr master alloy, and Al-Sr master alloy are added, and the temperature in the melting furnace is maintained until the master alloys and silicon raw materials are completely melted. S23. Reduce the temperature of the smelting furnace to 690℃~720℃, then press the magnesium raw material into the melt and maintain the temperature in the smelting furnace until the magnesium raw material is completely melted.

5. The high-toughness die-cast aluminum alloy containing chromium according to claim 1, wherein, The aluminum raw material is one or more of pure aluminum or aluminum ingots for remelting with a quality of not less than Al99.80, and / or the silicon raw material is one or more of pure silicon or industrial silicon with a quality of not less than Si4410.

6. The method for preparing a high-toughness die-cast aluminum alloy containing chromium according to any one of claims 1, 4, and 5, wherein, The quality inspection in S7 includes one or more of the following: chemical composition inspection, density inspection, and slag content inspection.

7. The method for preparing a high-toughness die-cast aluminum alloy containing chromium according to any one of claims 1, 4, and 5, wherein, In step S9, the refined aluminum liquid in the transfer package is transferred into a heat-preserving furnace located on one side of the die-casting machine for heat preservation.

8. A high-toughness die-cast aluminum alloy product containing chromium, characterized in that, The aluminum alloy product comprises a high-toughness die-cast aluminum alloy containing chromium as described in any one of claims 1 to 3; Or at least a portion of the aluminum alloy article is obtained by reprocessing a high-toughness die-cast aluminum alloy containing chromium as described in any one of claims 1 to 3.

Images