Cast aluminum alloy and preparation method and application thereof

Abstract

The invention discloses a cast aluminum alloy and a preparation method and application thereof. A regenerated aluminum alloy material is adopted as a raw material, the content of each component in the regenerated aluminum alloy material is detected, the components and the content are blended according to a target formula of the cast aluminum alloy, after the components are qualified, melting is conducted, and a melt is obtained and cast forming is conducted; wherein in the process of detecting the content of each component in the regenerated aluminum alloy material, the detection content and the detection total content corresponding to zirconium and titanium elements are obtained; corresponding casting processes are selected according to different detected total contents; the method solves the problem of poor performance or large fluctuation when a regenerated aluminum alloy material containing microalloy elements, especially zirconium and titanium elements, is used as a raw material to prepare a cast aluminum alloy at present, and can be used for preparing an aluminum alloy product with excellent performance; and a reliable way is provided for the level use and even upgrading use of the renewable and recyclable aluminum.

Description

Technical Field

[0001] This invention relates to the field of aluminum alloy technology, and more particularly to cast aluminum alloys, specifically to a cast aluminum alloy, its preparation method, and its application. Background Technology

[0002] The aerospace, rail transportation, and automotive industries are all pursuing lightweighting, and aluminum alloys are widely used due to their lightweight and high strength. Al-Si casting alloys, in particular, are an important system for cast aluminum alloys due to their good filling properties, low hot cracking resistance, and excellent mechanical properties. With technological advancements, higher demands are being placed on the strength, toughness, corrosion resistance, and fatigue resistance of cast aluminum alloys. This has led to the widespread use of microalloying elements in current alloy formulations, making the formulations more complex. Elements such as Zr and Ti can refine grains, improve mechanical properties, enhance heat resistance and fatigue performance, and improve the microstructure of the alloy; they are widely used microalloying elements in aluminum alloys.

[0003] For example, CN118745541A describes a high-strength, high-toughness, heat-treasure-free die-cast aluminum alloy prepared by adding 0-0.3 wt.% Zr to refine grains and improve performance; CN115491552B discloses a method for improving the corrosion resistance of cast alloys by adding corrosion modifiers, including Zr and Cr, to Al-Si-Cu-Mg alloys to enhance corrosion resistance by forming a passivation film on the surface; CN114774741A discloses a heat-resistant casting... Aluminum alloys are improved by using Zr to form the Al3Zr heat-resistant dispersed phase. CN115261682B adds Zr with a mass fraction of (0.1-0.5)% and obtains a non-shear strengthening phase through appropriate heat treatment, giving the alloy high fatigue performance. Meanwhile, Ti plays an important role in heterogeneous nucleation and limiting grain growth. Al-10Ti, Al-5Ti-B, and Al-3Ti-B are currently widely used grain refiners for aluminum alloys in the industry. It is evident that many technical solutions employ Zr for microalloying, and Ti is also widely present in aluminum alloys. The extensive use of Zr, Ti, and Si in Al-Si casting alloys makes them difficult to avoid in recycled alloy ingots. However, in practice, such as for casting of molded automotive chassis structural parts, once the formula content is determined, it is generally believed that a fixed forming process can be selected, or different forming processes can be selected for casting in different scenarios. But once recycled aluminum alloy materials are used, the performance of the aluminum alloy products prepared is difficult to guarantee, and may even deteriorate significantly, thus causing problems for the parallel or even upgraded use of renewable aluminum.

[0004] It should be noted that the information disclosed in the background section above is only for understanding the background of this application. Therefore, the background section of this invention may include background information about the problems or environment of this invention, and is not necessarily a description of the prior art. Thus, the content included in the background section does not constitute an admission of the prior art by the applicant. Summary of the Invention

[0005] The purpose of this invention is to overcome one or more shortcomings in the prior art and provide an improved method for preparing cast aluminum alloys.

[0006] Furthermore, this method solves the problem of poor performance or large fluctuations in the current preparation of cast aluminum alloys using recycled aluminum alloys containing microalloying elements, especially zirconium and titanium, as raw materials. This method is applicable to the preparation of aluminum alloy products with excellent performance using recycled aluminum alloys containing microalloying elements, especially zirconium and titanium, as raw materials, and provides a reliable way for the equal use and even the upgraded use of renewable aluminum.

[0007] This invention also provides a cast aluminum alloy prepared by the above-mentioned method and its application in the preparation of aluminum alloy products such as automotive chassis structural parts, steering knuckles, shock absorber towers, etc.

[0008] To achieve the above objectives, the present invention employs the following technical solution: A method for preparing a cast aluminum alloy, the method comprising: Recycled aluminum alloy material is used as raw material and the content of each component in the recycled aluminum alloy material is tested. The composition and content are adjusted according to the target formula of the cast aluminum alloy. After the composition is qualified, it is melted and cast into shape. In the process of detecting the content of each component in the recycled aluminum alloy material, the detection content of zirconium and titanium elements respectively and the total detection content of the two are obtained. When the total content detected is less than 0.25 wt.%, the casting process employs low-pressure casting, gravity casting, squeeze casting, or high-pressure casting; when the total content detected is greater than or equal to 0.25 wt.% and less than 0.35 wt.%, the casting process employs low-pressure casting, gravity casting, or high-pressure casting; when the total content detected is greater than or equal to 0.35 wt.% and less than 0.6 wt.%, the casting process employs high-pressure casting.

[0009] In this invention, the casting methods of "low-pressure casting, gravity casting, squeeze casting, and high-pressure casting" are all commonly used casting processes in the field, and their definitions and operation methods are well known in the field. Generally speaking, (1) gravity casting refers to the casting process that uses the Earth's gravity as the sole or main driving force to allow molten metal to flow naturally into a pre-made mold cavity (sand mold, metal mold, etc.) under the action of gravity, and cool and solidify in the cavity to form a casting.

[0010] (2) Low-pressure casting refers to a casting process in which molten metal in a sealed crucible is slowly "pushed" (from bottom to top through a riser pipe) to the mold cavity using low-pressure dry gas (e.g., 0.02-0.15 MPa) as the driving force. After filling, the pressure is maintained until the molten metal completely solidifies, and the casting is finally obtained. During the casting process, the filling speed is slow and the pressure is controllable, which can reduce molten metal splashing and air entrapment.

[0011] (3) Extrusion casting (also known as "liquid die forging") refers to the process of directly injecting a quantitative amount of molten metal into the cavity of a metal mold and immediately applying a high mechanical pressure (e.g., 10-150 MPa) to rapidly fill the mold under pressure and solidify under continuous high pressure, accompanied by slight plastic deformation (to compensate for solidification shrinkage) to finally form a dense casting.

[0012] (4) High pressure casting (abbreviated as "die casting") refers to a high-efficiency casting process that uses high mechanical pressure (e.g., 30-150MPa, or even up to 300MPa) and extremely fast filling speed (e.g., 0.5-50m / s) as the core to rapidly press molten metal into the cavity of a metal mold (die casting mold). The molten metal instantly fills the cavity under high pressure and solidifies rapidly. Then the mold is opened and the casting is taken out.

[0013] In this invention, the graded values ​​“0.25wt.%”, “0.35wt.%”, and “0.6wt.%” involved in detecting the total content are obtained by the following method: combining ternary and quaternary alloy phase diagrams such as Al-Si-Zr, Al-Si-Ti, and Al-Si-Zr-Ti, the critical values ​​are obtained by observing the microstructure of the castings under different graded values, conducting performance tests, and statistically analyzing the results.

[0014] In some embodiments of the present invention, the cast aluminum alloy is an aluminum-silicon alloy containing zirconium and titanium.

[0015] Furthermore, in the target formulation of the aluminum-silicon alloy, the zirconium content is 0.01wt.%-0.50wt.% and the titanium content is 0.05wt.%-0.30wt.%.

[0016] In this invention, the zirconium content is in the range of 0.01wt.%-0.50wt.%, where "0.01wt.%-0.40wt.%" can be 0.01wt.%, 0.02wt.%, 0.03wt.%, 0.04wt.%, 0.05wt.%, 0.06wt.%, 0.07wt.%, 0.08wt.%, 0.09wt.%, 0.1wt.%, 0.12wt.%, 0.15wt.%, 0.16wt.%, 0.18wt.%, 0.2wt.%, 0.22wt.%, 0.25wt.%, 0.28wt.%, 0.3wt.%, 0.32wt.%, 0.35wt.%, 0.38wt.%, 0.40wt.%, 0.42wt.%, 0.45wt.%, 0.48wt.%, etc.

[0017] In this invention, the titanium content is in the range of 0.05wt.%-0.30wt.%, where "0.05wt.%-0.30wt.%" can be 0.05wt.%, 0.06wt.%, 0.07wt.%, 0.08wt.%, 0.09wt.%, 0.1wt.%, 0.12wt.%, 0.15wt.%, 0.16wt.%, 0.18wt.%, 0.2wt.%, 0.22wt.%, 0.25wt.%, 0.28wt.%, 0.3wt.%, etc.

[0018] In some embodiments of the present invention, when the casting process is carried out using low-pressure casting or gravity casting, the cooling rate is controlled to be greater than or equal to 0.3 K / s (Kelvin per second) and less than 10 K / s.

[0019] In some embodiments of the present invention, when the casting process is performed by extrusion casting, the cooling rate is controlled to be greater than or equal to 10 K / s and less than 70 K / s.

[0020] In some embodiments of the present invention, when the casting process is performed using high-pressure casting, the cooling rate is controlled to be greater than or equal to 70 K / s and less than 200 K / s.

[0021] In some embodiments of the present invention, in the target formulation of the cast aluminum alloy, the target weight content of zirconium is expressed as [Zr]% and the target weight content of titanium is expressed as [Ti]%; [Zr]% max The percentage represents the maximum allowable amount of zirconium added in the target formulation. When the casting process employs squeeze casting, [Zr]×[Ti]≤1.45×10 -2 ; When the casting process employs low-pressure casting or gravity casting, [Zr] max =0.35-1.2×[Ti]; When the casting process employs high-pressure casting, [Zr] max =0.6-1.2×[Ti].

[0022] In this invention, the above-mentioned "[Zr], [Ti], [Zr]" max The relationship between "" was discovered by the inventors of this invention during a large number of experimental studies. Specifically, during the research process, castings of aluminum alloys with different Zr and Ti contents were prepared using different casting processes. The microstructure of the Al-Si-Zr-Ti second phase in the casting body was observed, and the morphology, size, and distribution of the second phase were statistically analyzed. Combined with the mechanical property test results, the Zr and Ti contents, microstructure, and properties were linked together, and the above formula was obtained through curve fitting.

[0023] In some embodiments of the present invention, the recycled aluminum alloy material accounts for 1 wt.%-70 wt.%, or 20 wt.%-70 wt.%, or 40 wt.%-70 wt.% of the melt.

[0024] Furthermore, the numerical range "1wt.%-70wt.%" includes, but is not limited to, 1wt.%, 5wt.%, 10wt.%, 15wt.%, 20wt.%, 25wt.%, 28wt.%, 30wt.%, 32wt.%, 35wt.%, 38wt.%, 40wt.%, 42wt.%, 45wt.%, 50wt.%, 55wt.%, 58wt.%, 60wt.%, 62wt.%, 65wt.%, 68wt.%, 70wt.%, etc.

[0025] In some embodiments of the present invention, the methods for detecting the content of each component in the recycled aluminum alloy material include laser-induced breakdown spectroscopy, spark direct reading spectroscopy, or inductively coupled plasma atomic emission spectrometry.

[0026] In some embodiments of the present invention, the recycled aluminum alloy material is replaced with virgin aluminum alloy material.

[0027] In this invention, "recycled aluminum alloy material" (also known as recycled aluminum alloy ingot or recycled aluminum ingot) refers to aluminum alloy waste that has been recycled twice.

[0028] In this invention, "new aluminum alloy material" refers to aluminum alloy ingots used for the first time.

[0029] Another technical solution provided by the present invention: a cast aluminum alloy prepared by the above-described method for preparing cast aluminum alloy.

[0030] According to the present invention, the alloy microstructure of the cast aluminum alloy comprises an Al-Si-Zr-Ti second phase, wherein the average size of the Al-Si-Zr-Ti second phase is less than or equal to 2 μm.

[0031] Another technical solution provided by the present invention: an aluminum alloy product, wherein the aluminum alloy product is made of a cast aluminum alloy comprising the above-described material.

[0032] Due to the application of the above technical solution, the present invention has the following advantages compared with the prior art: This invention solves the problem of agglomerated needle-like Al-Si-Zr-Ti phase formation caused by Zr / Ti composition fluctuations in cast aluminum alloys, and the resulting performance degradation. The method of this invention transforms Zr / Ti fluctuations in recycled aluminum from a risk factor into a strengthening resource. The average size of the Al-Si-Zr-Ti second phase can be reduced to below 2 μm, and the size of harmful phases is significantly reduced, even by more than 92%. The agglomerated needle-like distribution is changed to a scattered blocky distribution, essentially eliminating the adverse effects of the second phase. Simultaneously, it transforms the phase into a dispersed Al-Si-Zr-Ti phase beneficial to the alloy's fatigue and heat resistance properties. This increases the utilization rate of recycled aluminum (compared to primary aluminum ingots, the parallel or even upgraded use of recycled aluminum can significantly reduce carbon emissions, meeting the development direction of green and low-carbon aluminum; therefore, achieving efficient utilization of recycled aluminum is of great significance), improves alloy fatigue performance, reduces alloy production costs, and provides fundamental material technology support for automotive lightweighting. Attached Figure Description

[0033] Figure 1 This is a safety window diagram for Zr and Ti at different cooling rates in embodiments of the present invention; Figure 2 Microscopic image of the microstructure of the steering knuckle obtained in Example 1 after heat treatment (scale bar is 10 μm); Figure 3 Micrograph of the microstructure of the steering knuckle obtained in Example 1 after heat treatment (scale bar is 500 nm). Figure 4 Microscopic image of the microstructure of the steering knuckle obtained in Comparative Example 1; Figure 5 The fracture surface micrograph of the steering knuckle obtained in Comparative Example 1 is shown. Figure 6 The image shows a micrograph of the tissue structure of the H-arm obtained in Comparative Example 2. Detailed Implementation

[0034] Hypoeutectic Al-Si alloys exhibit a narrow solid-liquid crystallization temperature range, good fluidity and feeding properties, excellent casting performance, low production costs, virtually no casting cracks, low coefficient of thermal expansion, good corrosion resistance, good wear resistance, and machinability, making them widely used. Meanwhile, Zr and Ti elements are extensively used in Al-Si alloys due to their role in microalloying, heterogeneous nucleation, and limiting grain growth. Consequently, when recycling these aluminum alloys, Zr, Ti, and Si elements are almost unavoidable components. However, in practice, when these alloys are reused as recycled materials, the performance of the processed products cannot be guaranteed, and may even deteriorate significantly. This hinders the recycling of recycled materials, limits the increase in their addition ratio, and creates difficulties for the horizontal and even upgraded use of recyclable aluminum.

[0035] Based on extensive experimental research, the inventors of this invention unexpectedly discovered that even a difference of only 0.05 wt.% in the total amount of Al-Si-rich Zr+Ti elements in the Al-Si-Zr-Ti quaternary system can produce Al-Si-Zr-Ti quaternary intermetallic compounds. These compounds typically have a lamellar or needle-like morphology, with a size ranging from 20 μm to 100 μm, concentrated in the 30 μm to 60 μm range. This significantly reduces the fillability of the alloy and deteriorates its properties, thus posing a greater challenge to the microstructure control of the alloy.

[0036] Meanwhile, in practice, different forming processes have completely different solidification pressures and cooling rates. Even with the same alloy composition, the microstructure can vary significantly, leading to inconsistent alloy properties. Therefore, the optimal alloy composition window differs for different forming processes.

[0037] Based on the above, the inventors of this invention innovatively proposed to classify the total amount of Zr+Ti elements in recycled aluminum alloy materials, with different levels corresponding to their respective suitable casting methods (in fact, the applicable processes are not entirely the same for different total amounts of Zr+Ti elements in recycled aluminum alloy materials), and adjust the Zr and Ti element content of recycled aluminum alloy materials to the target value content through dynamic compensation, thereby solving the problems existing in the prior art.

[0038] Furthermore, in the preparation process of this invention, the choice of casting method is also affected by the target content of zirconium and titanium elements in the target formula of the cast aluminum alloy. Different casting methods correspond to different target content relationships of zirconium and titanium elements. In other words, the alloy composition windows of different forming processes are incompatible, and the maximum allowable addition amount of Zr and Ti microalloying elements is different. A single composition scheme cannot meet the requirements of fast cooling / slow cooling processes.

[0039] Furthermore, this invention adjusts the corresponding cooling rate according to different casting methods, thereby constructing a dynamic matching model of "cooling rate-composition-recycled material". This process, which dynamically and in real time adjusts the appropriate and matching process based on the real-time composition content data of recycled aluminum alloy material, constructs a preparation method that can be directly applied, laying the foundation for the direct application of recycled aluminum alloy materials with different compositions and contents.

[0040] See Figure 1 As shown, this is a safety window diagram for Zr and Ti at different cooling rates in an embodiment of the present invention. It can be seen from the diagram that the safety window area corresponding to the cold rate process of extrusion casting is very narrow, and different cooling rates correspond to different safe contents of Zr and Ti.

[0041] In some cases, the method for preparing the cast aluminum alloy of the present invention includes: using recycled aluminum alloy material as raw material and detecting the content of each component in the recycled aluminum alloy material; adjusting the composition and content according to the target formula of the cast aluminum alloy; melting and casting after the composition is qualified. In the process of detecting the content of each component in recycled aluminum alloy material, the corresponding detection content of zirconium and titanium elements and the total detection content of the two were obtained. When the total content is less than 0.25 wt.%, low-pressure casting, gravity casting, squeeze casting, or high-pressure casting is used for casting. When the total content is greater than or equal to 0.25 wt.% and less than 0.35 wt.%, low-pressure casting, gravity casting, or high-pressure casting is used for casting. When the total content is greater than or equal to 0.35 wt.% and less than 0.6 wt.%, high-pressure casting is used for casting.

[0042] The cast aluminum alloy is an aluminum-silicon alloy containing zirconium and titanium. Further, in the target formulation of the aluminum-silicon alloy, the zirconium content is 0.01 wt.%-0.40 wt.%, and the titanium content is 0.05 wt.%-0.30 wt.%.

[0043] Furthermore, when low-pressure casting or gravity casting is used, the cooling rate is controlled to be greater than or equal to 0.3 K / s (Kelvin per second) and less than 10 K / s; when extrusion casting is used, the cooling rate is controlled to be greater than or equal to 10 K / s and less than 70 K / s; when high-pressure casting is used, the cooling rate is controlled to be greater than or equal to 70 K / s and less than 200 K / s.

[0044] Furthermore, in the target formulation of the cast aluminum alloy, the target weight content of zirconium is expressed as [Zr]% and the target weight content of titanium is expressed as [Ti]%; [Zr]% max The percentage represents the maximum allowable amount of zirconium added in the target formulation. When squeeze casting is used, [Zr]×[Ti]≤1.45×10 -2 ; When low-pressure casting or gravity casting is used for casting, [Zr] max =0.35-1.2×[Ti]; When high-pressure casting is used for molding, [Zr] max =0.6-1.2×[Ti].

[0045] This invention reduces or even eliminates the formation of micron-sized (20μm~100μm) Al-Si-Zr-Ti second phases, allowing more elements to dissolve in the aluminum matrix and subsequently precipitate as dispersed phases of 50-200nm, thus improving the alloy's fatigue resistance and heat resistance. It addresses the pain point of multi-process co-line production of automotive chassis components, increases the proportion of recycled aluminum used, enhances alloy fatigue performance, reduces alloy production costs, and provides fundamental material technology support for automotive lightweighting. Furthermore, it significantly improves the fatigue life of chassis castings and the utilization rate of recycled aluminum.

[0046] The above-mentioned solution will be further described below with reference to specific embodiments; it should be understood that these embodiments are used to illustrate the basic principles, main features and advantages of the present invention, and the present invention is not limited to the scope of the following embodiments; the implementation conditions used in the embodiments can be further adjusted according to specific requirements, and the implementation conditions not specified are usually the conditions in conventional experiments.

[0047] Unless otherwise specified in the following examples, all raw materials are commercially available or prepared by conventional methods in the art. Example 1:

[0048] This example provides a cast aluminum alloy and its preparation method. The target formulation of the cast aluminum alloy is: Si: 7wt.%, Cu: 0.5wt.%, Mg: 0.34wt.%, Mn: 0.2wt.%, Cr: 0.15wt.%, Ti: 0.08wt.%, Zr: 0.12wt.%, Fe: 0.3wt.%, Sr: 0.02wt.%, impurity content ≤0.2wt.%, and the balance is Al.

[0049] This alloy was used to manufacture steering knuckles.

[0050] Preparation methods include: S1 Melting: First, preheat the crucible to 200℃ and hold for 30 minutes. Then, set the melting temperature to 760℃ and add recycled aluminum ingots. After the aluminum ingots are completely melted, use laser-induced breakdown spectroscopy to detect the content of each component in the recycled aluminum ingots online. Use Al-10Si, Al-10Mn, Al-10Cr master alloys, Cu wire, and Mg blocks to adjust the composition to the target content. The Ti and Zr contents in the recycled aluminum ingot are: Ti: 0.06 wt.%, Zr: 0.07 wt.%; the calculated total Ti and Zr content is 0.13 wt.%; using Al-10Ti and Al-10Zr master alloys, the Ti and Zr contents are Ti: 0.08 wt.% and Zr: 0.12 wt.%, respectively. S2: Modification: When the alloy melt temperature reaches 730℃, Al-10Sr modifier is added and the temperature is held for 10 minutes before casting a mushroom-shaped sample with qualified composition. After the composition is qualified, a uniform melt is obtained. S3 Refining: The melt is refined using rotary argon injection and external refining agents to remove inclusions and gases from the melt. A general-purpose refining agent is added using a rotary argon injection process for refining and slag removal, with the processing temperature controlled at 720℃, followed by settling and slag removal. The refining agent is FL-228, and its addition amount is 0.1% of the alloy melt weight. The argon purity is 99.99%, the height of the degassing graphite rotor from the bottom of the crucible is 20mm, the rotation speed is 450r / min, the argon flow rate is 20L / min, and the refining time is 20min.

[0051] S4 Molding: The casting process of the steering knuckle is extrusion casting, with a cooling rate of 50K / s; the mold temperature controller is used to control the cooling rate of the casting at 50k / s, and the holding pressure is 110MPa.

[0052] S5 heat treatment: 535℃ holding for 8 hours + water quenching + aging at 170℃ for 12 hours. After cooling, samples are taken from the ingot for microstructure observation and performance testing. Example 2:

[0053] This example provides a cast aluminum alloy and its preparation method. The target formula of the cast aluminum alloy is: Si: 8wt.%, Mn: 0.5wt.%, Mg: 0.4wt.%, Cr: 0.2wt.%, Ti: 0.2wt.%, Zr: 0.25wt.%, Fe: 0.3wt.%, Sr: 0.015wt.%, impurity content ≤0.2wt.%, and balance Al.

[0054] This alloy was used to manufacture vibration damping towers.

[0055] Preparation methods include: Recycled aluminum ingots were used as raw materials, and the content of each component in the recycled aluminum ingots was determined online using laser-induced breakdown spectroscopy. The results showed that Ti was 0.18 wt.% and Zr was 0.19 wt.%. The total amount of Ti and Zr was calculated to be 0.37 wt.%. The composition and content of the cast aluminum alloy were adjusted according to the target formula, with Al-10Ti and Al-10Zr master alloys added respectively, so that the Ti and Zr contents were Ti: 0.2 wt.% and Zr: 0.25 wt.%. The target formulation of the cast aluminum alloy does not contain copper, therefore, there is no need to adjust the content using Cu wire; the casting process of the shock absorber tower is high-pressure casting with a cooling rate of 100K / s; the vacuum degree is 60mbar, the mold temperature is controlled at 200℃, and the casting pressure is 80MPa. This material is a heat-free aluminum alloy and does not require heat treatment. The remaining preparation process is the same as in Example 1. Example 3:

[0056] This example provides a cast aluminum alloy and its preparation method. The target formulation of the cast aluminum alloy is: Si: 7wt.%, Cu: 0.5wt.%, Mg: 0.4wt.%, Mn: 0.3wt.%, Cr: 0.15wt.%, Ti: 0.14wt.%, Zr: 0.17wt.%, Fe: 0.3wt.%, Sr: 0.015wt.%, impurity content ≤0.2wt.%, and the balance is Al.

[0057] Hollow H-arms were prepared using this alloy.

[0058] Preparation methods include: Recycled aluminum ingots were used as raw materials, and the content of each component in the recycled aluminum ingots was determined online using laser-induced breakdown spectroscopy. The results showed that Ti was 0.13 wt.% and Zr was 0.16 wt.%. The total amount of Ti and Zr was calculated to be 0.29 wt.%. The composition and content of the cast aluminum alloy were adjusted according to the target formula, with Al-5Ti-1B and Al-10Zr master alloys added respectively, so that the Ti and Zr contents were Ti: 0.14 wt.% and Zr: 0.17 wt.%. The hollow H-arm is formed by low-pressure semi-metallic mold casting, with a cooling rate of 8K / s, a mold temperature of 200℃, and a casting pressure of 0.5MPa.

[0059] The remaining preparation process is the same as in Example 1.

[0060] Comparative Example 1: This example provides a cast aluminum alloy and its preparation method. The target formulation of the cast aluminum alloy is: Si: 7.1 wt.%, Cu: 0.5 wt.%, Mg: 0.34 wt.%, Mn: 0.2 wt.%, Cr: 0.15 wt.%, Ti: 0.13 wt.%, Zr: 0.12 wt.%, Fe: 0.3 wt.%, Sr: 0.02 wt.%, impurity content ≤ 0.2 wt.%, and the balance is Al.

[0061] This alloy was used to manufacture steering knuckles.

[0062] Preparation methods include: Recycled aluminum ingots were used as raw materials, and the content of each component in the recycled aluminum ingots was determined online using laser-induced breakdown spectroscopy. The results showed that Ti was 0.11 wt.% and Zr was 0.07 wt.%. The total amount of Ti and Zr was calculated to be 0.18 wt.%. The composition and content of the cast aluminum alloy were adjusted according to the target formula, with Al-5Ti-1B and Al-10Zr master alloys added respectively, so that the Ti and Zr contents were Ti: 0.13wt.% and Zr: 0.12wt.% respectively. The steering knuckle is formed by extrusion casting with a cooling rate of 50 K / s; the casting cooling rate is controlled by a mold temperature controller at 50 K / s, and the holding pressure is 110 MPa.

[0063] The remaining preparation process is the same as in Example 1.

[0064] Comparative Example 2: This example provides a cast aluminum alloy and its preparation method. The target formulation of the cast aluminum alloy is: Si: 7wt.%, Cu: 0.5wt.%, Mg: 0.34wt.%, Mn: 0.2wt.%, Cr: 0.15wt.%, Ti: 0.16wt.%, Zr: 0.25wt.%, Fe: 0.3wt.%, Sr: 0.02wt.%, impurity content ≤0.2wt.%, and the balance is Al.

[0065] H-arms were prepared using this alloy.

[0066] Preparation methods include: Recycled aluminum alloy was used as raw material, and the content of each component in the recycled aluminum alloy was detected online using laser-induced breakdown spectroscopy. The results showed that Ti was 0.16 wt.% and Zr was 0.25 wt.%, with a calculated total content of 0.41 wt.%. The composition and content are adjusted according to the target formula of the cast aluminum alloy; The H-arm is cast using a low-pressure semi-metallic mold casting process, with a cooling rate of 8K / s, a mold temperature of 200℃, and a casting pressure of 0.5MPa.

[0067] The remaining preparation process is the same as in Example 1.

[0068] Performance testing: (1) See the microstructure diagram of the steering knuckle obtained in Example 1. Figure 2 As shown, the average size of the Al-Si-Zr-Ti second phase is approximately 1.8 μm, exhibiting a scattered, blocky distribution. Simultaneously, the dissolved Zr and Ti elements precipitate as dispersed phases. Figure 3 As shown; The steering knuckle body was tested under the following conditions: stress ratio R = -1, frequency = 40Hz, and cycle period = 10. 7 The ultimate fatigue strength is 112 MPa.

[0069] In the microstructure of the damping tower obtained in Example 2, the average size of the Al-Si-Zr-Ti second phase is approximately 1.7 μm, exhibiting a scattered blocky distribution. The test conditions were a stress ratio R of -1, a frequency of 40 Hz, and a cycle period of 10. 7 The ultimate fatigue strength is 103 MPa.

[0070] In the hollow H-arm microstructure obtained in Example 3, the average size of the Al-Si-Zr-Ti second phase is approximately 2 μm, exhibiting a scattered blocky distribution. The test conditions were a stress ratio R of -1, a frequency of 40 Hz, and a cycle period of 10. 7 The ultimate fatigue strength is 110 MPa.

[0071] (2) See the microstructure diagram of the steering knuckle obtained in Comparative Example 1. Figure 4 As shown, see the fracture surface. Figure 5 As shown, the average size of the Al-Si-Zr-Ti second phase is approximately 25 μm, exhibiting an agglomerated needle-like distribution; the test conditions were a stress ratio R of -1, a frequency of 40 Hz, and a cycle period of 10. 7 The ultimate fatigue strength is 100 MPa. Therefore, when the target Ti and Zr contents in the cast aluminum alloy formulation are Ti: 0.13 wt.% and Zr: 0.12 wt.%, respectively, 0.13 × 0.12 = 1.56 × 10⁻⁶ MPa. -2 The product is greater than 1.45 × 10 -2 At this point, squeeze casting cannot achieve good performance.

[0072] See the tissue structure diagram of the H-arm obtained in Comparative Example 2. Figure 6 As shown, the average size of the Al-Si-Zr-Ti second phase is approximately 20 μm, exhibiting an agglomerated needle-like distribution; the test conditions were a stress ratio R of -1, a frequency of 40 Hz, and a cycle period of 10. 7The ultimate fatigue strength is 95 MPa. It can be seen that when the total amount of Ti and Zr in the recycled aluminum ingot is 0.41 wt.%, only high-pressure casting is suitable. Furthermore, when the target formulation content of the cast aluminum alloy is Ti: 0.16 wt.% and Zr: 0.25 wt.%, [Zr]... max =0.35-1.2×[Ti]=0.158. The Zr content in the target formulation is 0.25wt.% which is significantly higher than 0.158. Therefore, the ideal performance cannot be obtained by low-pressure casting.

[0073] As used throughout the specification and claims, the term "comprising" is an open-ended term and should be interpreted as "comprising but not limited to." "Substantially" means that within an acceptable margin of error, those skilled in the art can solve the technical problem and substantially achieve the technical effect. It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a product or system comprising a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a product or system. Without further limitations, an element defined by the phrase "comprising one" does not exclude the presence of other identical elements in the product or system comprising said element.

[0074] The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

[0075] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

Claims

1. A method for producing a cast aluminum alloy, characterized by, The preparation method comprises: The recycled aluminum alloy material is used as raw material, and the content of each component in the recycled aluminum alloy material is detected, the components and contents are adjusted according to the target formula of the cast aluminum alloy, and after the components are qualified, melting is performed to obtain a melt and cast into a product; In the process of detecting the content of each component in the recycled aluminum alloy material, the detection content of zirconium and titanium elements respectively and the total detection content of zirconium and titanium are obtained; When the total detection content is less than 0.25wt.%, the casting is performed by low-pressure casting, gravity casting, extrusion casting or high-pressure casting; when the total detection content is greater than or equal to 0.25wt.% and less than 0.35wt.%, the casting is performed by low-pressure casting, gravity casting or high-pressure casting; when the total detection content is greater than or equal to 0.35wt.% and less than 0.6wt.%, the casting is performed by high-pressure casting.

2. The method of producing a cast aluminum alloy according to claim 1, characterized by, The cast aluminum alloy is an aluminum-silicon aluminum alloy containing zirconium and titanium.

3. The method of producing a cast aluminum alloy according to claim 2, characterized by, In the target formula of the aluminum-silicon aluminum alloy, the content of zirconium is 0.01wt.% to 0.50wt.%, and the content of titanium is 0.05wt.% to 0.30wt.%.

4. The method of producing a cast aluminum alloy according to claim 1, characterized by, When the casting is performed by low-pressure casting or gravity casting, the cooling speed is controlled to be greater than or equal to 0.3K / s and less than 10K / s; and / or, When the casting is performed by extrusion casting, the cooling speed is controlled to be greater than or equal to 10K / s and less than 70K / s; and / or, When the casting is performed by high-pressure casting, the cooling speed is controlled to be greater than or equal to 70K / s and less than 200K / s.

5. The method of producing a cast aluminum alloy according to claim 1, characterized by, In the cast aluminum alloy target formulation, a target weight content of zirconium is expressed as [Zr]%, a target weight content of titanium is expressed as [Ti]%, and [Zr] is a maximum allowable addition amount of zirconium in the target formulation. max % is a maximum allowable addition amount of zirconium in the target formulation. When the cast forming employs squeeze casting, [Zr] x [Ti] < 1.45 x 10 -2 ; When the cast forming employs low pressure casting or gravity casting, [Zr] max = 0.35 - 1.2 x [Ti]; When the cast forming employs high pressure casting, [Zr] max = 0.6 - 1.2 x [Ti].

6. The method of producing a cast aluminum alloy according to claim 1, characterized by, In the melt, the recycled aluminum alloy material accounts for 1wt.% to 70wt.%, or 20wt.% to 70wt.%, or 40wt.% to 70wt.%; and / or, The method for detecting the content of each component in the recycled aluminum alloy material comprises laser-induced breakdown spectroscopy, spark direct-reading spectroscopy or inductively coupled plasma emission spectroscopy.

7. The method of producing a cast aluminum alloy according to any one of claims 1 to 6, characterized in that, The recycled aluminum alloy material is replaced by a primary aluminum alloy material.

8. A cast aluminum alloy prepared by the preparation method of the cast aluminum alloy according to any one of claims 1 to 7.

9. The cast aluminum alloy of claim 8, wherein, The alloy structure of the cast aluminum alloy comprises Al-Si-Zr-Ti second phases, and the average size of the Al-Si-Zr-Ti second phases is less than or equal to 2μm.

10. An aluminum alloy product characterized by, The aluminum alloy product is prepared by the cast aluminum alloy according to claim 8 or 9. The aluminum alloy product is prepared by the cast aluminum alloy according to claim 8 or 9.

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