Easily-demoulded high-strength cast aluminum alloy material and preparation method thereof

Abstract

The invention discloses an easy-to-demould high-strength cast aluminum alloy material and a preparation method thereof, and belongs to the technical field of motors for new energy automobiles. The cast aluminum alloy material is prepared from the following components in parts by weight: 0.4 to 0.8 weight percent of Mg, 0.7 to 1.0 weight percent of Si, 0.15 to 0.4 weight percent of VIII group elements and the balance of Al and inevitable impurities. The cast aluminum alloy material prepared in the invention is easy to demold during molding and demolding, adhesion between molten aluminum liquid and a mold is reduced, the quality and demolding efficiency of a cast aluminum rotor adopting the alloy material are improved, meanwhile, the influence on the mold can be reduced, and the service life of the mold is prolonged.

Description

Technical Field

[0001] This application relates to an easily demolded, high-strength cast aluminum alloy material and its preparation method, belonging to the field of motor technology for new energy vehicles. Background Technology

[0002] As motor speeds continue to increase, higher demands are placed on the strength and conductivity of cast aluminum alloy materials. Currently, aluminum alloys used for cast aluminum rotors have high nickel and copper content, and most achieve improved rotor performance through the combination of five or more elements. However, such formulations not only increase production costs but also make the molten aluminum difficult to melt due to the excessive element composition, leading to adhesion of the mold and thus affecting the performance of the cast aluminum rotor.

[0003] Since cast aluminum rotors are used in new energy vehicles, and with the public's pursuit of low energy consumption in new energy vehicles, the lightweighting of cast aluminum rotors has become a current research hotspot. Currently, the lightweighting of cast aluminum rotors is mainly achieved by preparing thin-walled cast aluminum rotors. However, when demolding thin-walled cast aluminum rotors, the aluminum liquid contains a large number of elements that are prone to precipitation, causing the aluminum liquid to stick to the mold, which in turn affects the quality of the cast aluminum rotor and also reduces the mold life.

[0004] Therefore, there is an urgent need for a cast aluminum alloy material that is easy to demold and has high strength for preparing thin-walled materials. Summary of the Invention

[0005] To address the aforementioned issues, a high-strength cast aluminum alloy material that is easy to demold is provided. This material facilitates demolding during the fabrication of thin-walled cast aluminum rotors, ensuring the quality and shape of the rotors while maintaining their strength, thus guaranteeing their stability and safety in use.

[0006] According to one aspect of this application, a high-strength cast aluminum alloy material that is easy to demold is provided, comprising, by weight: Mg: 0.4~0.8wt%, Si: 0.7~1.0wt%, Group VIII elements: 0.15~0.4wt%, with the balance being Al and unavoidable impurities.

[0007] In this application, Mg is added to the cast aluminum alloy material for three reasons: First, Mg has a certain solid solubility in the aluminum matrix. When Mg enters the aluminum lattice, it causes lattice distortion, and the resulting stress field hinders dislocation movement, thereby improving the strength and hardness of the alloy. Second, Mg can form the Mg2Si phase with Si, which significantly improves the strength of the aluminum alloy through precipitation strengthening mechanism. Third, Mg can form a dense oxide film on the alloy surface, preventing the intrusion of external corrosive media and improving the corrosion resistance of the aluminum alloy.

[0008] The addition of Si can form a eutectic structure with Al with a low melting point. At the casting temperature, the eutectic structure can melt before the matrix, thereby filling various parts of the casting, reducing casting defects, and improving the quality and dimensional accuracy of the casting. At the same time, Si reacts with Mg to form the Mg2Si phase, which further enhances the strength of the alloy.

[0009] Adding Group VIII elements, such as Ni and Fe, helps improve the high-temperature hardness and strength of aluminum alloys, enabling cast aluminum rotors made from this material to maintain good mechanical properties in high-temperature environments and meet their usage requirements under specific working conditions.

[0010] Optionally, the cast aluminum alloy material comprises, by mass fraction, Mg, Si and Group VIII elements in a weight ratio of (1.5-1.8):(2.0-2.5):1.

[0011] The amount of Si added in the cast aluminum alloy material of this application is higher than that of Mg and Group VIII elements. At this ratio, the strength of the aluminum alloy can be effectively enhanced. At the same time, the eutectic structure formed by Si and Al melts before the matrix, which facilitates the demolding of the cast aluminum rotor using the alloy material, reduces casting defects, and improves the quality of the cast aluminum rotor.

[0012] If the amount of Si added is higher than the above ratio, it will easily cause the aluminum liquid to contain more free silicon. Free silicon exists in the aluminum matrix in the form of block or needle-like crystals. When subjected to external force, the stress is easily concentrated at the edges or interfaces of the free silicon crystals, forming microcracks. This causes the material to fracture under low stress, which greatly reduces the impact resistance and fatigue resistance of the cast aluminum rotor, making it unable to withstand the vibration and load when the motor is running at high speed.

[0013] If the amount of Mg added is higher than the above ratio, a large number of coarse β-Mg2Si will be formed. When subjected to impact, vibration or high temperature load, cracks are easily generated from these structures and propagate rapidly, causing brittle fracture of the rotor, which cannot withstand the working intensity of the motor.

[0014] Optionally, the group VIII elements include at least one of Fe, Co, Ni, and Ir.

[0015] Among them, Fe can form the α-AlFeSi phase with Al and Si. This phase has moderate hardness and is evenly distributed, which can avoid stress concentration. Secondly, it can refine the primary grains in the aluminum liquid, reduce dendrite segregation during solidification, and make the aluminum liquid fill the mold more smoothly.

[0016] Co can stabilize the alloy structure at high temperatures, preventing strength degradation. Co can form Al9Co2 and Al2O3 with Al and Si elements. 13Co4 and other Al-Co-Si ternary intermetallic compounds have melting points exceeding 800℃ and are not easily coarsened at high temperatures, enabling the rotor to maintain high resistance to deformation under high speed and high temperature conditions.

[0017] The Al3Ni phase formed by Ni and Al can significantly improve the high-temperature hardness and creep resistance of the rotor, preventing the rotor from deforming due to creep under long-term high temperature.

[0018] Ir and Al can form AlIr2 intermetallic compounds. These phases have high thermal stability and can maintain structural stability and non-coarsening at high temperatures, which can ensure the stability of the rotor's mechanical properties at high temperatures. At the same time, they can not only refine the grains during casting solidification, but also effectively inhibit grain growth and recrystallization during subsequent heat treatment or long-term high-temperature use, fundamentally ensuring the long-term stability of the rotor structure.

[0019] Optionally, the group VIII elements include Fe and Ni in a weight ratio of 1:(1.5-1.8).

[0020] At the above-mentioned addition ratios, blocky or granular α-AlFeSi phases can be formed, which can avoid brittle fracture caused by stress concentration and will not affect subsequent processing. At the same time, the presence of Fe can inhibit the excessive formation of coarse Al3Ni phases by Ni. The synergy of the two allows the Al3Ni phase to precipitate in a finer and more dispersed state, which retains the strengthening effect and avoids the decrease in material plasticity caused by coarse Ni phases, thus significantly improving the rotor's resistance to deformation and fatigue at high temperatures.

[0021] Optionally, the group VIII elements include Fe, Ni, and Co in a weight ratio of 1:(1.5-1.8):(0.1-0.15).

[0022] At the aforementioned ratios, Fe can refine α-Al grains. Co has a similar effect; it promotes the precipitation of the α-Al phase, increasing its quantity in the microstructure. Furthermore, with increasing Co content, the size and distribution of the α-Al phase become more uniform, thus refining the overall grain structure of the cast aluminum alloy. In addition, Ni, working synergistically with Fe, can transform the easily formed needle-like β-AlFeSi phase in molten aluminum into blocky or granular α-AlFeSi phases, reducing their cutting effect on the matrix. Simultaneously, Co can inhibit the precipitation of the β-Al5FeSi phase, reducing its quantity and resulting in a more uniform distribution of intermetallic compounds, thus improving material properties.

[0023] Optionally, the group VIII elements include Fe, Ni, and Ir in a weight ratio of 1:(1.5-1.8):(0.05-0.1):.

[0024] At the above ratio, stress can be transmitted more evenly in the grain boundaries and matrix, reducing stress concentration. It also reduces the generation of microcracks on the material surface and the formation of internal residual stress, thereby improving the fatigue resistance of the cast aluminum rotor and extending its service life.

[0025] Another aspect of this application provides a method for preparing a high-strength cast aluminum alloy material that is easy to demold, comprising the following steps: S1: Pre-treat the Al raw material to obtain the pre-treated Al raw material; S2: Place the Al raw material into the melting furnace, heat it to 700-720℃, add the weighed Si and Mg elements, stir evenly after complete dissolution, add the refining agent for the first refining, keep it at the temperature for 10-15 minutes, let it stand and remove the slag to obtain intermediate liquid A. S3: Heat intermediate liquid A to 720-730℃, add the weighed Group VIII element, add the refining agent again for a second refining, keep warm for 20-30 minutes, let stand and remove the slag to obtain intermediate liquid B; S4: Preheat the casting mold, then cool the intermediate liquid B to 720℃ and pour it into the casting mold for centrifugation. After the alloy material solidifies, the casting equipment stops rotating and cools naturally for 60-100 seconds. Then, air cool to room temperature to obtain the casting. S5: The casting is heat-treated and then naturally cooled to room temperature to obtain the final product.

[0026] Optionally, the preprocessing includes the following steps: S10: Soak the Al raw material in 5-8 times its volume of oxalic acid solution for 20-30 minutes; S20: Dry the Al raw material obtained in S10 to obtain the treated Al raw material.

[0027] Soaking Al raw materials in oxalic acid has several advantages. First, oxalic acid reacts with and removes some impurities in the Al raw materials, reducing their impact on the smelting process and product quality. Second, it helps remove the oxide film on the surface, increasing the bonding force between alloying elements and the Al matrix during subsequent smelting, resulting in a more uniform alloy composition. Third, it allows for faster and more uniform melting, reducing smelting time and energy consumption, and improving production efficiency. Fourth, during the smelting process, the oxalic acid on the surface of the Al raw materials decomposes at high temperatures to generate CO gas. CO readily undergoes a redox reaction with active hydrogen, thus efficiently removing active hydrogen from the high-temperature molten aluminum.

[0028] Optionally, the centrifugation speed in step (3) is 180-200 r / min and the centrifugation time is 20-25 s.

[0029] Optionally, in the casting mold, the temperature of the upper mold is 560-580℃, and the temperature of the lower mold is 400-420℃.

[0030] Optionally, during the first refining process, the injection rate of the refining agent is controlled at 0.5-0.6 kg / min, and during the second refining process, the injection rate of the refining agent is controlled at 0.7-0.9 kg / min.

[0031] Controlling the injection speed of the refining agent can promote the uniformity of the reaction between the refining agent and the molten aluminum. This allows the refining agent to be evenly dispersed in the molten aluminum as fine particles, maximizing the contact interface between the refining agent and the molten aluminum. This accelerates the core refining reactions such as desulfurization, dephosphorization, and deoxidation, thereby improving the quality and refining efficiency of cast aluminum alloy materials. If the injection speed is too fast, the refining agent is prone to agglomerate on the surface of the molten aluminum, and some of the refining agent cannot be integrated into the interior of the molten aluminum in time, only reacting locally on the surface, resulting in incomplete reaction. Conversely, if the speed is too slow, the diffusion range of the refining agent in the molten aluminum is limited, the overall reaction rate is significantly reduced, and the refining processing time is prolonged, reducing product production efficiency.

[0032] Optionally, the refining agent is cryolite.

[0033] Optionally, the heat treatment process in step S5 is as follows: S100: Heat the casting to 300-320℃ at a heating rate of 5-10℃ / min and hold for 2-3 hours. Then heat to 380-400℃ at a heating rate of 20-30℃ and hold for 1-2 hours. S200: The heat-insulated cast aluminum alloy material is placed in a coolant to cool to room temperature. The coolant contains 5-15wt% control agent and the remainder is water. The cooling rate of the coolant is 15-25℃ / s in the range of 300-400℃ and 40-80℃ / s below 300℃. S300: Heat to 150-160℃ at a heating rate of 5℃ / min and hold for 5 hours.

[0034] Optionally, the control agent is selected from polyvinyl alcohol, sodium alginate and sulfonated cellulose in a weight ratio of 5:2:1.

[0035] Optionally, the molecular weight of polyvinyl alcohol is 200,000-250,000, the molecular weight of sodium alginate is 300,000-350,000, and the molecular weight of sulfonated cellulose is 20,000-40,000.

[0036] The beneficial effects of this application include, but are not limited to: 1. The high-strength cast aluminum alloy material of this application is easy to demold, which reduces the adhesion between molten aluminum and the mold, improves the quality and demolding efficiency of the cast aluminum rotor, and also reduces the impact on the mold and extends the service life of the mold.

[0037] 2. The easy-to-demold, high-strength cast aluminum alloy material according to this application is better suited for the production of thin-walled products, enabling thin-walled products to maintain high strength and toughness while reducing thickness. It can achieve lightweighting of cast aluminum rotors while ensuring normal operation of rotors at speeds of 18,000-25,000 rpm, improving operational safety and preventing breakage and damage to cast aluminum rotors during use.

[0038] 3. The easy-to-demold, high-strength cast aluminum alloy material of this application can refine the grains and improve the uniformity of grain distribution by adding Si, Mg and Group VIII elements, thereby improving the strength and hardness of the cast aluminum rotor.

[0039] 4. According to the easy-to-demold high-strength cast aluminum alloy material of this application, the addition of group VIII elements can not only refine the grains and the uniformly distributed phase structure, enabling stress to be transmitted more evenly in the grain boundaries and matrix, reducing stress concentration, but also reduce the generation of microcracks on the material surface and the formation of internal residual stress, thereby improving the fatigue resistance of the cast aluminum rotor and extending its service life. Detailed Implementation

[0040] The present application is described in detail below with reference to the embodiments, but the present application is not limited to these embodiments.

[0041] Unless otherwise specified, the raw materials used in the embodiments and comparative examples of this application were all purchased commercially.

[0042] Unless otherwise specified, the methods used in the embodiments and comparative examples of this application are conventional methods in the prior art. The control agents used in the following embodiments and comparative examples are all commercially available products, and the preparation methods of sulfonated cellulose are also existing methods in the prior art. They can be purchased directly or prepared directly by referring to existing technologies, such as patent CN119638854A.

[0043] Example 1 This embodiment relates to an easy-to-demold, high-strength cast aluminum alloy material, which, by weight, comprises: Mg: 0.4wt%, Si: 0.7wt%, Fe: 0.15wt%, with the balance being Al and unavoidable impurities.

[0044] The method for preparing cast aluminum rotors using this easily demolded, high-strength cast aluminum alloy material includes the following steps: S1: Pre-treat the Al raw material to obtain the pre-treated Al raw material; the pre-treatment includes the following steps: S10: Soak the Al raw material in 5 times the amount of 1wt% oxalic acid solution for 20 minutes; S20: Dry the Al raw material obtained in S10 to obtain the treated Al raw material; S2: Place the Al raw material into a melting furnace, heat it to 700℃, add the weighed Si and Mg elements, stir evenly after complete dissolution, add cryolite refining agent, control the injection speed of the refining agent to 0.5kg / min for the first refining, keep it at the temperature for 10min, let it stand and remove the slag to obtain intermediate liquid A. S3: Heat intermediate liquid A to 720℃, add the weighed Fe element, add cryolite refining agent again, control the injection rate of refining agent to 0.7kg / min for the second refining, keep warm for 20min, let stand and remove slag to obtain intermediate liquid B; S4: Preheat the casting mold, with the upper mold at 560℃ and the lower mold at 400℃. Then pour the intermediate liquid B at 720℃ into the casting mold for centrifugation at 180r / min for 20s. After the rotor solidifies, the casting equipment stops rotating and is allowed to cool naturally for 60s. Then, it is air-cooled to room temperature to obtain the casting. S5: The casting is heat-treated and then naturally cooled to room temperature to obtain the final product; the specific heat treatment process is as follows: S100: Heat the casting to 320℃ at a heating rate of 5℃ / min, hold for 3 hours, then heat to 400℃ at a heating rate of 20℃, and hold for 2 hours. S200: The heat-insulated rotor is placed in a coolant to cool to room temperature. The coolant contains 5 wt% control agent and the remainder is water. The control agent is selected from polyvinyl alcohol (molecular weight 250,000), sodium alginate (molecular weight 350,000), and sulfonated cellulose (molecular weight 20,000) in a weight ratio of 5:2:1. The cooling rate of the coolant is 15℃ / s in the range of 300-400℃ and 40℃ / s below 300℃. S300: Heat to 160℃ at a heating rate of 5℃ / min and hold for 5 hours.

[0045] Example 2 This embodiment relates to a high-strength cast aluminum alloy material that is easy to demold, comprising, by weight: Mg: 0.8wt%, Si: 1.0wt%, Fe: 0.4wt%, with the balance being Al and unavoidable impurities.

[0046] The method for preparing cast aluminum rotors using this easily demolded, high-strength cast aluminum material includes the following steps: S1: Pre-treat the Al raw material to obtain the pre-treated Al raw material; the pre-treatment includes the following steps: S10: Soak the Al raw material in 8 times its volume of 1wt% oxalic acid solution for 30 minutes; S20: Dry the Al raw material obtained in S10 to obtain the treated Al raw material; S2: Place the Al raw material into the melting furnace, heat it to 720℃, add the weighed Si and Mg elements, stir evenly after complete dissolution, add cryolite refining agent, control the injection rate of the refining agent to 0.6 kg / min for the first refining, after 20 min of treatment, let it stand and remove the slag to obtain intermediate liquid A. S3: Heat intermediate liquid A to 730℃, add the weighed Fe element, add cryolite refining agent again, control the injection rate of refining agent to 0.9kg / min for the second refining, keep warm for 15min, let stand and remove slag to obtain intermediate liquid B; S4: Preheat the casting mold, with the upper mold at 580℃ and the lower mold at 420℃. Then, cool the intermediate liquid B to 720℃ and pour it into the casting mold for centrifugation at 200r / min for 25s. After the rotor solidifies, stop the casting equipment and allow it to cool naturally for 100s. Then, air-cool it to room temperature to obtain the casting. S5: The casting is heat-treated and then naturally cooled to room temperature to obtain the final product; the specific heat treatment process is as follows: S100: Heat the casting to 300℃ at a heating rate of 10℃ / min, hold for 2 hours, then heat to 380℃ at a heating rate of 30℃, and hold for 1 hour. S200: The heat-insulated rotor is placed in a coolant to cool to room temperature. The coolant contains 15wt% control agent and the remainder is water. The control agent is selected from polyvinyl alcohol (molecular weight 200,000), sodium alginate (molecular weight 300,000), and sulfonated cellulose (molecular weight 40,000) in a weight ratio of 5:2:1. The cooling rate of the coolant is 25℃ / s in the range of 300-400℃ and 80℃ / s below 300℃. S300: Heat to 150℃ at a heating rate of 5℃ / min and hold for 5 hours.

[0047] Example 3 This embodiment relates to an easy-to-demold, high-strength cast aluminum alloy material, which, by weight, comprises: Mg: 0.6wt%, Si: 0.8wt%, Fe: 0.20wt%, Ni: 0.15wt%, with the balance being Al and unavoidable impurities.

[0048] The method for preparing cast aluminum rotors using this easily demolded, high-strength cast aluminum alloy material includes the following steps: S1: Pre-treat the Al raw material to obtain the pre-treated Al raw material; the pre-treatment includes the following steps: S10: Soak the Al raw material in 7 times its volume of 1wt% oxalic acid solution for 25 minutes; S20: Dry the Al raw material obtained in S10 to obtain the treated Al raw material; S2: Place the Al raw material into the melting furnace, heat it to 710℃, add the weighed Si and Mg elements, stir evenly after complete dissolution, add cryolite refining agent, control the injection rate of the refining agent to 0.55kg / min for the first refining, after 15min of treatment, let it stand and remove the slag to obtain intermediate liquid A. S3: Heat intermediate liquid A to 730℃, add weighed Fe and Ni elements, add cryolite refining agent again, control the injection rate of refining agent to 0.8kg / min for a second refining, keep warm for 13min, let stand and remove slag to obtain intermediate liquid B; S4: Preheat the casting mold, with the upper mold temperature at 570℃ and the lower mold temperature at 410℃. Then, cool the intermediate liquid B to 720℃ and pour it into the casting mold for centrifugation at a speed of 190r / min for 23s. After the rotor solidifies, the casting equipment stops rotating and is allowed to cool naturally for 80s. Then, it is air-cooled to room temperature to obtain the casting. S5: The casting is heat-treated and then naturally cooled to room temperature to obtain the final product; the specific heat treatment process is as follows: S100: Heat the casting to 310℃ at a heating rate of 8℃ / min, hold for 2.5h, then heat to 390℃ at a heating rate of 25℃, and hold for 1.5h. S200: The heat-insulated rotor is placed in a coolant to cool to room temperature. The coolant contains 10 wt% control agent and the remainder is water. The control agent is selected from polyvinyl alcohol (molecular weight 220,000), sodium alginate (molecular weight 320,000), and sulfonated cellulose (molecular weight 30,000) in a weight ratio of 5:2:1. The cooling rate of the coolant is 20℃ / s in the range of 300-400℃ and 60℃ / s below 300℃. S300: Heat to 155℃ at a heating rate of 5℃ / min and hold for 5 hours.

[0049] Example 4 The difference between this embodiment and Embodiment 3 is that the Fe element content is 0.15wt%.

[0050] Example 5 The difference between this embodiment and Embodiment 3 is that the cast aluminum rotor also includes 0.1wt% Co.

[0051] Example 6 The difference between this embodiment and Embodiment 3 is that the cast aluminum rotor also includes 0.1wt% Ir element.

[0052] Example 7 The difference between this embodiment and embodiment 3 is that the temperature is raised to 800°C in step S2.

[0053] Example 8 The difference between this embodiment and embodiment 3 is that step S3 is not performed.

[0054] Example 9 The difference between this embodiment and embodiment 3 is that the centrifugation speed in step S4 is 100 r / min.

[0055] Example 10 The difference between this embodiment and embodiment 3 is that acrylamide is used instead of sulfonated cellulose in step S200 of step S5.

[0056] Example 11 The difference between this embodiment and embodiment 3 is that step S1 is not performed.

[0057] Comparative Example 1 The difference between this comparative example and Example 3 is that 0.20 wt% Cu was used instead of Fe.

[0058] Comparative Example 2 The difference between this comparative example and Example 3 is that 0.15wt% Zn is used to replace Ni.

[0059] Comparative Example 3 The difference between this comparative example and Example 3 is that the amount of Fe added is 0.7 wt%.

[0060] Comparative Example 4 The difference between this comparative example and Example 3 is that the amount of Ni added is 0.05 wt%.

[0061] Comparative Example 5 The difference between this comparative example and Example 3 is that the amount of Mg added is 1.2 wt%.

[0062] Comparative Example 6 The difference between this comparative example and Example 3 is that the amount of Mg added is 0.3 wt%.

[0063] Comparative Example 7 The difference between this comparative example and Example 3 is that the amount of Si element added is 0.5 wt%.

[0064] Comparative Example 8 The difference between this comparative example and Example 3 is that the amount of Si added is 1.3 wt%.

[0065] Test Example 1 Mechanical properties and electrical conductivity tests were conducted on end face samples of the cast aluminum rotors prepared in the above embodiments and comparative examples. The electrical conductivity test specimens met the requirements of GB / T12966-2008 and were tested for electrical conductivity. The mechanical property test specimens met the standard of ASTM E8 and were analyzed for tensile properties. The impact resistance was tested using a cantilever beam impact strength tester in accordance with GB / T1843-2008. The demolding force was tested by setting a pressure sensor in the mold and monitoring the ejection force of the ejection unit when the product was demolded to quantitatively measure the demolding force of the product. The specific structure can be referred to the structure disclosed in CN204094106. The results are shown in Table 1.

[0066] Table 1

[0067] The above description is merely an embodiment of this application, and the scope of protection of this application is not limited to these specific embodiments, but is determined by the claims of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the technical concept and principles of this application should be included within the scope of protection of this application.

Claims

1. A high-strength cast aluminum alloy material that is easy to demold, characterized in that, By weight, it includes: Mg: 0.4~0.8wt%, Si: 0.7~1.0wt%, Group VIII elements: 0.15%~0.4wt%, with the balance being Al and unavoidable impurities.

2. The easily demolded, high-strength cast aluminum alloy material according to claim 1, characterized in that, The weight ratio of Mg, Si and Group VIII elements, by mass fraction, is (1.5-1.8):(2.0-2.5):

1.

3. The easily demolded, high-strength cast aluminum alloy material according to claim 1, characterized in that, The group VIII elements include at least one of Fe, Co, Ni, and Ir.

4. The easily demolded, high-strength cast aluminum alloy material according to claim 1, characterized in that, The group VIII elements include Fe and Ni in a weight ratio of 1:(1.5-1.8).

5. The easily demolded, high-strength cast aluminum alloy material according to claim 1, characterized in that, The group VIII elements include Fe, Ni, and Co in a weight ratio of 1:(1.5-1.8):(0.1-0.15).

6. The easily demolded, high-strength cast aluminum alloy material according to claim 1, characterized in that, The group VIII elements include Fe, Ni, and Ir in a weight ratio of 1:(1.5-1.8):(0.05-0.1):.

7. A method for preparing an easily demolded, high-strength cast aluminum alloy material according to any one of claims 1 to 6, characterized in that, The preparation method includes the following steps: S1: Pre-treat the Al raw material to obtain the pre-treated Al raw material; S2: Place the Al raw material into the melting furnace, heat it to 700-720℃, add the weighed Si and Mg elements, stir evenly after complete dissolution, add the refining agent for the first refining, keep it at the temperature for 10-15 minutes, let it stand and remove the slag to obtain intermediate liquid A. S3: Heat intermediate liquid A to 720-730℃, add the weighed Group VIII element, add the refining agent again for a second refining, keep warm for 20-30 minutes, let stand and remove the slag to obtain intermediate liquid B; S4: Preheat the casting mold, then cool the intermediate liquid B to 720℃ and pour it into the casting mold for centrifugation. After the alloy material solidifies, the casting equipment stops rotating and cools naturally for 60-100 seconds. Then, air cool to room temperature to obtain the casting. S5: The casting is heat-treated and then naturally cooled to room temperature to obtain the final product.

8. The preparation method according to claim 7, characterized in that, In step S4, the centrifugation speed is 180-200 r / min and the centrifugation time is 20-25 s.

9. The preparation method according to claim 7, characterized in that, In the casting mold, the temperature of the upper mold is 560-580℃, and the temperature of the lower mold is 400-420℃.

10. The preparation method according to claim 7, characterized in that, During the first refining process, the injection rate of the refining agent is controlled at 0.5-0.6 kg / min. During the second refining process, the injection rate of the refining agent is controlled at 0.7-0.9 kg / min.

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