A high-strength piston aluminum alloy and its preparation method

Abstract

This invention relates to the field of aluminum alloy technology, specifically to a high-strength piston aluminum alloy. The raw material composition, by weight percentage, is as follows: Si: 11.5-12.0%, Cu: 4.35-4.55%, Ni: 2.2-2.6%, Mg: 1.0-1.15%, V: 0.08-0.11%, Ti: 0.08-0.11%, Zr: 0.06-0.09%, Fe: 0.3-0.4%, P: ≥0.0060%, with the remainder being Al. This invention also provides a method for preparing the high-strength piston aluminum alloy, comprising the following steps: S1, aluminum alloy melting; S2, aluminum liquid refining; S3, aluminum alloy piston heat treatment. The high-strength piston aluminum alloy prepared by this invention exhibits better tensile strength and plasticity, meeting the requirements for high-performance production of high-strength pistons.

Description

Technical Field

[0001] This invention relates to the field of aluminum alloy technology, specifically to a high-strength piston aluminum alloy and its preparation method. Background Technology

[0002] Aluminum and aluminum alloys possess numerous excellent properties, including lightweight, corrosion resistance, ease of formability, high specific strength, high electrical and thermal conductivity, and easy recyclability, making them widely used in various industries such as construction, automobiles, aircraft, shipbuilding, and defense. Multi-element Al-Si alloys containing alloying elements such as Cu, Ni, Mg, V, Ti, and Zr exhibit good casting properties and a low coefficient of linear expansion. Furthermore, the presence of intermetallic reinforcing phases enhances the alloy's hardness and strength, resulting in good wear resistance and corrosion resistance. These alloys meet the material requirements for density, high-temperature fatigue strength, coefficient of thermal expansion, thermal conductivity, heat resistance, and wear resistance, and are commonly used in the manufacture of lightweight, high-strength components such as internal combustion engine pistons.

[0003] The piston is the most demanding and structurally complex moving part in an internal combustion engine. Its main function is to withstand the combustion pressure in the cylinder and transmit this force to the crankshaft through the piston pin and connecting rod. Because the piston is in direct contact with high-temperature, high-pressure combustion gases, it bears significant thermal and mechanical loads. Simultaneously, the increasing engine power and torque lead to a substantial rise in combustion chamber pressure and temperature, requiring the piston to withstand higher thermomechanical loads. This places higher demands on the strength of aluminum alloy pistons: room temperature tensile strength ≥280MPa, room temperature elongation ≥1%, high temperature (350℃) tensile strength ≥90MPa, high temperature (350℃) elongation ≥7%, volumetric stability ≤0.01%D, linear expansion coefficient (20-400℃) ≤21.8x10-6 / ℃, and metallographic structure at the piston throat ≤4 grade. Previously, the requirements for aluminum alloy pistons were room temperature tensile strength ≥225MPa, room temperature elongation... Elongation ≥ 0.5%, high temperature (350℃) tensile strength ≥ 80MPa, high temperature (350℃) elongation ≥ 2%, volume stability ≤ 0.01%D, linear expansion coefficient (20-300℃) ≤ 21.5x10-6 / ℃, metallographic structure of piston throat ≤ grade 4; compared with the original piston performance requirements, the main improvement of aluminum alloy piston performance is in tensile strength and elongation. The minimum room temperature tensile strength is increased by 55MPa, the minimum room temperature elongation is increased by 0.5%, the minimum high temperature (350℃) tensile strength is increased by 10MPa, and the minimum high temperature (350℃) elongation is increased by 5%.

[0004] Currently, aluminum alloy pistons are generally produced using gravity casting. Due to the slow cooling rate during solidification, the microstructure contains large blocky primary silicon and rod-shaped eutectic silicon. Additionally, the piston material contains impurities such as Fe, and Mn is added to improve Fe morphology. Both elements reduce the piston material's fatigue strength and thermal conductivity. While existing material composition and casting processes can generally meet requirements, they are no longer sufficient for increasingly stringent applications. Measures need to be taken to improve the overall performance of aluminum pistons, including material composition, alloy refinement, and piston heat treatment, to extend their service life. Summary of the Invention

[0005] The purpose of this invention is to provide an aluminum-silicon alloy material for pistons that has high strength, high elongation, and high fatigue strength, in order to address the problems and shortcomings of existing technologies.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A high-strength piston aluminum alloy, the raw materials are composed of the following components by weight percentage: Si: 11.5-12.0%, Cu: 4.35-4.55%, Ni: 2.2-2.6%, Mg: 1.0-1.15%, V: 0.08-0.11%, Ti: 0.08-0.11%, Zr: 0.06-0.09%, Fe: 0.3-0.4%, P: ≥0.0060%, with the remainder being Al.

[0008] A method for preparing a high-strength aluminum alloy piston includes the following preparation steps:

[0009] S1, Aluminum alloy smelting;

[0010] S2, aluminum liquid refining;

[0011] S3, heat treatment of aluminum alloy piston.

[0012] Specifically, step S1 includes the following sub-steps:

[0013] S11. Add silicon to the bottom of the industrial frequency furnace, then pour in the molten aluminum from the natural gas continuous melting furnace, then add copper and nickel, turn on the industrial frequency furnace to heat up, and when the temperature of the molten aluminum reaches 780℃±20℃, add magnesium alloy, aluminum-vanadium alloy, aluminum-titanium alloy, aluminum-zirconium alloy, and aluminum-phosphorus alloy.

[0014] S12. Continue heating to 900-930℃ for heat preservation and diffusion melting, with a heat preservation and diffusion time of 20-40 minutes;

[0015] S13. Take component samples and, after the components are qualified, proceed with the water effluent operation.

[0016] Specifically, step S2 includes the following sub-steps:

[0017] S21. Pretreatment of aluminum liquid to remove Ca: Pretreatment temperature: 770-790℃; Degasser speed controlled at 480-520 rpm, gas pressure controlled at 0.5-0.6MPa, gas flow rate controlled at 5-15L / min, add a certain amount of Ca removal flux, and degas for 5 minutes.

[0018] S22. Aluminum liquid refining treatment, refining temperature: 770-790℃; pour 60g-90g of refining agent into the aluminum liquid vortex along the edge of the vortex for refining treatment, and the refining and degassing time is 10 minutes.

[0019] S23. Aluminum liquid standing: After the aluminum liquid is refined, it should be left to stand for 10 minutes. The quality of the aluminum liquid should be tested with a density equivalent meter. If the density equivalent DI value is ≤0.6, the slag can be removed, the ladle opened, and the liquid poured.

[0020] Specifically, in step S21, the method for adding the Ca removal flux is as follows: the degassing rotor is placed in the center of the crucible (molten aluminum) and rotated. After the molten aluminum forms a relatively large vortex, a certain amount of Ca removal flux is poured into the molten aluminum vortex along the edge of the vortex, and the rotation continues to remove gas.

[0021] Specifically, the Ca-removing flux is FUSAL 1956.

[0022] Specifically, the refining agent is Pyroflux GR DR212.

[0023] Specifically, step S3 includes the following sub-steps:

[0024] S31. Casting and quenching treatment of aluminum piston skirt: The piston blank temperature shall not be less than 420℃. Take out the piston blank and immediately put it into the quenching box. The quenching position shall be with the stop facing downwards. The immersion depth shall not be lower than the center of the pin hole and not exceed the top of the pin hole.

[0025] S32. Two aging treatments: The first aging is 180℃×5h, with the furnace temperature ≤50℃ and the heating time ≥45 minutes. After that, the furnace is removed and air-cooled to room temperature before the second aging is performed. The second aging is 245℃×2h, with the furnace temperature ≤50℃ and the heating time ≥60 minutes.

[0026] Specifically, in step S31, the quenching temperature is 60-90℃.

[0027] Based on the above technical solution, the embodiments of the present invention can produce at least the following technical effects:

[0028] (1) The present invention provides a high-strength piston aluminum alloy, wherein the Cu content is selected in the range of 4.35-4.55%, the Mg content is selected in the range of 1.0-1.15%, and the Ni content is selected in the range of 2.2-2.6%. The main purpose is to utilize the good strengthening and hardening effects of Cu, Mg and Ni in this range to improve the mechanical strength performance of the piston.

[0029] (2) The present invention provides a high-strength piston aluminum alloy. Generally, Al-Si alloys used for cast pistons contain Mn, mainly to improve the needle-like and fishbone-like morphology formed by Fe. However, the present invention does not add Mn when reducing Fe impurities in the alloy. This is mainly to improve the thermal conductivity of the Al-Si alloy piston, allowing the heat generated in the combustion chamber of the piston head to be transferred quickly, thus enhancing the piston's fatigue resistance. Si is selected at the lower limit of Al-Si alloys; the present invention selects Si in the range of 11.5-12.0%, mainly to reduce the probability of primary silicon precipitation and reduce the hot cracking tendency of the Al-Si alloy. The addition of trace elements such as V, Ti, and Zr to the Al-Si alloy refines the as-cast structure, inhibits grain growth during recrystallization, refines primary silicon, and improves the alloy's tensile strength and plasticity.

[0030] (3) The present invention provides a method for preparing a high-strength piston aluminum alloy by adding an aluminum-phosphorus alloy modifier in the aluminum alloy smelting process, and holding the melting process at a high temperature of 900-930℃ for 20-40 minutes. While the alloy homogenization effect is good, the main function is to increase the content of free P element. Free P plays a role in inhibiting the growth of silicon phase and promoting the refinement of primary silicon.

[0031] (4) The present invention provides a method for preparing a high-strength piston aluminum alloy, which involves on-site pretreatment of molten aluminum to remove Ca and control of the amount of Ca-removing flux added. When the Ca content in the melt increases, it is easy to form high-melting-point AlCa compounds, which reduces the fluidity and feeding performance of the aluminum alloy. At the same time, it may also form a compound phase that is insoluble in the aluminum matrix (such as Al4Ca), thereby affecting the performance of the aluminum alloy after heat treatment. Excess Ca can also react with Al and Si to form coarse plate-like Al2Si2Ca phase. Moreover, the presence of Ca can also lead to the rupture of the Al2O3 oxide film, increase the hydrogen content of the molten aluminum and the probability of porosity and looseness in the casting, affecting the surface and internal quality of the product. Studies have shown that the lower the Ca content in the alloy, the more significant the modification effect of P and the smaller the average size of the primary silicon crystals. According to the Ca content in the molten aluminum, the corresponding Ca-removing flux is added. When Ca ≤ 0.001% and ≥ 0.006%, the modification effect of the molten aluminum is the best.

[0032] (5) The present invention provides a method for preparing a high-strength piston aluminum alloy by means of two sets of aging treatments. The first aging is 180℃×5h, which improves the aging strengthening effect and hardness of the Al-Si alloy piston and increases the tensile strength of the piston. The second aging is 245℃×2h, which improves the volume stability of the piston. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be described in detail below. The described embodiments are merely some embodiments of this invention, and not all embodiments. The invention will be further described in detail below with reference to the embodiments.

[0034] This invention provides a method for preparing a high-strength aluminum alloy piston, comprising an optimized aluminum alloy smelting process, an optimized aluminum liquid refining process, and an optimized aluminum alloy piston heat treatment process, specifically including the following steps:

[0035] 1. The aluminum alloy smelting process is carried out according to the following steps:

[0036] a) First, add silicon to the bottom of the industrial frequency furnace, then pour in the molten aluminum from the natural gas continuous melting furnace, then add copper and nickel, turn on the industrial frequency furnace to raise the temperature, and when the temperature of the molten aluminum reaches 780℃±20℃, add magnesium alloy, aluminum-vanadium alloy, aluminum-titanium alloy, aluminum-zirconium alloy, and aluminum-phosphorus alloy.

[0037] b) Continue heating to 900-930℃ for heat-holding diffusion melting, with a heat-holding diffusion time of 20-40 minutes;

[0038] c) Take component samples, and after the components meet the requirements, proceed with the effluent operation;

[0039] 2. The aluminum liquid refining process is carried out according to the following steps:

[0040] a) On-site pretreatment for removing Ca from molten aluminum: ① Pretreatment temperature: 770-790℃; ② When the degasser speed is controlled at 480-520 rpm, the gas pressure at 0.5-0.6 MPa, and the gas flow rate at 5-15 L / min, add a certain amount of Ca-removing flux and degas for 5 minutes; ③ Method of adding Ca-removing flux: Place the degasser rotor in the center of the crucible (molten aluminum) and rotate. After the molten aluminum forms a relatively large vortex, take a certain amount of Ca-removing flux and pour it into the vortex along the edge of the vortex, and continue rotating for degassing. The amount of Ca-removing flux added is shown in the table below:

[0041]

[0042] b) Aluminum liquid refining treatment: ① Refining temperature: 770-790℃; ② Pour 60g-90g of Pyroflux GR DR212 refining agent into the aluminum liquid vortex along the edge of the vortex for refining treatment; ③ Aluminum liquid refining degassing time: 10 minutes.

[0043] c) Aluminum liquid settling: After the aluminum liquid is refined, it should be settling for 10 minutes. The quality of the aluminum liquid should be tested with a density equivalent meter. If the density equivalent DI value is ≤0.6, the slag can be removed, the ladle opened, and the liquid poured.

[0044] 3. The heat treatment process for aluminum alloy pistons shall be carried out according to the following steps:

[0045] a) Casting and quenching treatment of aluminum piston skirt: Take out the piston blank and immediately put it into the quenching box. The temperature of the piston blank should not be less than 420℃. The quenching position should be with the stop facing down. The immersion depth should not be lower than the center of the pin hole and not exceed the top of the pin hole. The quenching temperature is 60-90℃.

[0046] b) Two aging treatments: The first aging is 180℃×5h, the furnace temperature is ≤50℃, and the heating time is ≥45 minutes. Then, the furnace is removed and air-cooled to room temperature before the second aging is performed. The second aging is 245℃×2h, the furnace temperature is ≤50℃, and the heating time is ≥60 minutes.

[0047] Example 1 1.1

[0049] Prepare 300 kg of molten aluminum alloy according to the above-mentioned aluminum alloy composition control requirements, and smelt the molten aluminum alloy according to the above-mentioned aluminum alloy smelting process requirements. Analyze the alloy composition. The composition of each component in the aluminum alloy is as follows: Si 11.72%, Cu 4.38%, Ni 2.45%, Mg 1.18%, V 0.085%, Ti 0.87%, Zr 0.08%, Fe 0.34%, P 0.0103%, Ca 0.0035%, with the remainder being Al. 1.2

[0051] The aluminum liquid refining process is carried out according to the above-mentioned requirements. The aluminum liquid refining process is as follows:

[0052] a) On-site aluminum liquid degassing pretreatment: The temperature of the aluminum liquid in the on-site holding furnace was measured to be 785℃. One quantitative ladle (80g) of FUSAL 1956 degassing flux was added, and the mixture was rotated to degas for 5 minutes.

[0053] b) Aluminum liquid refining treatment: The temperature of the pretreated aluminum liquid was detected to be 776℃. 65g of Pyroflux GRDR212 refining agent was added for refining and degassing treatment for 10 minutes.

[0054] c) Aluminum liquid standing: After the aluminum liquid is refined, it is left to stand for 10 minutes. The density equivalent DI value of the aluminum liquid is measured by a density equivalent meter and is 0.3.

[0055] d) Piston composition analysis: After refining the aluminum liquid, a sample was taken to analyze the piston composition. The composition of each component of the aluminum liquid alloy is as follows: Si 11.55%, Cu 4.35%, Ni 2.42%, Mg 1.07%, V 0.085%, Ti 0.09%, Zr 0.075%, Fe 0.35%, P 0.0064%, Ca 0.0003%, and the remainder is Al. 1.3

[0057] Aluminum piston casting was performed, with specific piston models used for casting example verification: The selected product model was NKM974ZL-B piston, cylinder diameter Φ138, and the casting machine was a ZG1400-Ⅱ lower core-pulling casting machine.

[0058] a) Casting process for the Φ138 cylinder diameter piston blank: casting temperature 760-780℃, shrinkage time 190 seconds, mold cooling process: outer mold 30 seconds of water rinsing 140 seconds; inner mold core continuous water rinsing; top mold 170 seconds of water rinsing 10 seconds; pin 10 seconds of water rinsing 30 seconds.

[0059] b) Perform skirt casting and quenching treatment according to the above aluminum piston skirt casting and quenching process, with a quenching temperature of 60-90℃. 1.4

[0061] Aging heat treatment of aluminum pistons:

[0062] a) The heat treatment furnace is a box-type resistance furnace, model RXS-90-3.

[0063] b) Perform two sets of aging treatments on the aluminum piston according to the above heat treatment aging process requirements.

[0064] Example 2 2.1

[0066] Prepare 300 kg of molten aluminum alloy according to the above-mentioned aluminum alloy composition control requirements, and smelt the molten aluminum alloy according to the above-mentioned aluminum alloy smelting process requirements. Analyze the alloy composition. The composition of each component in the aluminum alloy is as follows: Si 11.95%, Cu 4.58%, Ni 2.53%, Mg 1.15%, V 0.075%, Ti 0.10%, Zr 0.75%, Fe 0.38%, P 0.0108%, Ca 0.0068%, with the remainder being Al. 2.2

[0068] The aluminum liquid refining process is carried out according to the above-mentioned requirements. The aluminum liquid refining process is as follows:

[0069] a) On-site aluminum liquid degassing pretreatment: The temperature of the aluminum liquid in the on-site holding furnace was detected to be 788℃. Two quantitative ladles (160g) of FUSAL 1956 degassing flux were added, and the mixture was rotated to degas for 5 minutes.

[0070] b) Aluminum liquid refining treatment: The temperature of the pretreated aluminum liquid was detected to be 778℃. 70g of Pyroflux GRDR212 refining agent was added for refining and degassing treatment for 10 minutes.

[0071] c) Aluminum liquid standing: After the aluminum liquid is refined, it is left to stand for 10 minutes. The density equivalent DI value of the aluminum liquid is measured by a density equivalent meter and is 0.2.

[0072] d) Piston composition analysis: After refining the aluminum liquid, a sample was taken to analyze the piston composition. The composition of each component of the aluminum liquid alloy is as follows: Si 11.75%, Cu 4.52%, Ni 2.50%, Mg 1.04%, V 0.072%, Ti 0.093%, Zr 0.71%, Fe 0.37%, P 0.0068%, Ca 0.0002%, and the remainder is Al. 2.3

[0074] Aluminum piston casting: Selected piston model for casting example verification: Product model selected is YC4110ZLQ piston, cylinder diameter Φ110, casting machine model is ZG1400-Ⅱ lower core pulling casting machine.

[0075] a) Casting process for the Φ110 cylinder diameter piston blank: casting temperature 760-780℃, shrinkage time 140 seconds, mold cooling process: outer mold 30 seconds of water rinsing for 90 seconds; core continuous water rinsing; top mold 120 seconds of water rinsing for 10 seconds; pin air cooling.

[0076] b) Perform skirt casting and quenching treatment according to the above aluminum piston skirt casting and quenching process, with a quenching temperature of 60-90℃. 2.4

[0078] Aging heat treatment of aluminum pistons:

[0079] a) The heat treatment furnace is a box-type resistance furnace, model RXS-90-3.

[0080] b) Perform two sets of aging treatments on the aluminum piston according to the above heat treatment aging process requirements.

[0081] Example 3 3.1

[0083] Prepare 300 kg of molten aluminum alloy according to the above-mentioned aluminum alloy composition control requirements, and smelt the molten aluminum alloy according to the above-mentioned aluminum alloy smelting process requirements. Analyze the alloy composition. The composition of each component in the aluminum alloy is as follows: Si 11.86%, Cu 4.47%, Ni 2.35%, Mg 1.13%, V 0.088%, Ti 0.95%, Zr 0.85%, Fe 0.32%, P 0.0105%, Ca 0.0053%, with the remainder being Al. 3.2

[0085] The aluminum liquid refining process is carried out according to the above-mentioned requirements. The aluminum liquid refining process is as follows:

[0086] a) On-site aluminum liquid degassing pretreatment: The temperature of the aluminum liquid in the on-site holding furnace was measured to be 784℃. 1.5 metering scoops (120g) of FUSAL 1956 degassing flux was added and the mixture was rotated to degas for 5 minutes.

[0087] b) Aluminum liquid refining treatment: The temperature of the pretreated aluminum liquid was detected to be 775℃. 85g of Pyroflux GRDR212 refining agent was added for refining and degassing treatment for 10 minutes.

[0088] c) Aluminum liquid standing: After the aluminum liquid is refined, it is left to stand for 10 minutes. The density equivalent DI value of the aluminum liquid is measured by a density equivalent meter and is 0.3.

[0089] d) Piston composition analysis: After refining the aluminum liquid, a sample was taken to analyze the piston composition. The composition of each component of the aluminum liquid alloy is as follows: Si 11.66%, Cu 4.38%, Ni 2.25%, Mg 1.07%, V 0.082%, Ti 0.86%, Zr 0.78%, Fe 0.32%, P 0.0065%, Ca 0.0003%, and the remainder is Al. 3.3

[0091] Aluminum piston casting was performed, with specific piston models used for casting example verification: The product model selected was YN27CRE piston, cylinder diameter Φ90, and the casting machine was a ZG1400-Ⅱ lower core-pulling casting machine.

[0092] a) Casting process for the Φ90 cylinder diameter piston blank: casting temperature 760-780℃, shrinkage time 70 seconds, mold cooling process: outer mold 30 seconds of water rinsing, core mold continuous water rinsing, top mold 55 seconds of water rinsing, pin air cooling.

[0093] b) Perform skirt casting and quenching treatment according to the above aluminum piston skirt casting and quenching process, with a quenching temperature of 60-90℃. 2.4

[0095] Aging heat treatment of aluminum pistons:

[0096] a) The heat treatment furnace is a box-type resistance furnace, model RXS-90-3.

[0097] b) Perform two sets of aging treatments on the aluminum piston according to the above heat treatment aging process requirements.

[0098] Test case

[0099] Sampling locations for performance test samples: Samples for room temperature tensile strength, high temperature tensile strength, and coefficient of linear expansion were taken from the head area above the piston pin hole; metallographic analysis was performed from the combustion chamber throat area above the pin hole. Performance test data are shown in the table below:

[0100]

[0101] The test data in the table above shows that the aluminum alloy used to prepare high-strength pistons can achieve the following: room temperature tensile strength ≥280MPa, room temperature elongation ≥1%, high temperature (350℃) tensile strength ≥90MPa, high temperature (350℃) elongation ≥7%, volume stability ≤0.01%D, coefficient of linear expansion (20-400℃) ≤21.8x10-6 / ℃, and metallographic structure of the piston throat ≤4 grade, which meets the requirements for producing high-strength pistons.

[0102] It is understood that the present invention has been described through some embodiments, and those skilled in the art will recognize that various changes or equivalent substitutions can be made to these features and embodiments without departing from the spirit and scope of the invention. Furthermore, under the teachings of the present invention, these features and embodiments can be modified to adapt to specific situations and materials without departing from the spirit and scope of the invention. Therefore, the present invention is not limited to the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are within the protection scope of the present invention.

Claims

1. A method for preparing a high-strength piston aluminum alloy, characterized in that, The preparation steps include the following: S1. Aluminum alloy smelting, including the following sub-steps: S11. Add silicon to the bottom of the industrial frequency furnace, then pour in the molten aluminum from the natural gas continuous melting furnace, followed by copper and nickel. Turn on the industrial frequency furnace to raise the temperature until the molten aluminum reaches 780℃. Magnesium alloy, aluminum-vanadium alloy, aluminum-titanium alloy, aluminum-zirconium alloy, and aluminum-phosphorus alloy are added at 20℃. S12. Continue heating to 900-930℃ for heat preservation and diffusion melting, with a heat preservation and diffusion time of 20-40 minutes; S13. Take component samples and, after the components are qualified, proceed with the water effluent operation; S2. Aluminum liquid refining, including the following sub-steps: S21. Pretreatment of aluminum liquid to remove Ca: Pretreatment temperature: 770-790℃; Degasser speed controlled at 480-520 rpm, gas pressure controlled at 0.5-0.6 MPa, gas flow rate controlled at 5-15 L / min, add a certain amount of Ca removal flux, and degas for 5 minutes; The method of adding Ca removal flux is as follows: place the degasser rotor in the center of the aluminum liquid in the crucible and rotate it. After the aluminum liquid forms a relatively large vortex, take a certain amount of Ca removal flux and pour it into the aluminum liquid vortex along the edge of the vortex, and continue to degas by rotating. S22. Refining of molten aluminum, refining temperature: 770-790℃; pour 60g-90g of refining agent into the molten aluminum vortex along the edge of the vortex for refining, and the refining and degassing time is 10 minutes. S23. Aluminum liquid standing: After the aluminum liquid is refined, it should be left to stand for 10 minutes. The quality of the aluminum liquid should be tested with a density equivalent meter. If the density equivalent DI value is ≤0.6, the slag can be removed, the ladle opened, and the liquid poured. S3, heat treatment of aluminum alloy piston; The composition of the raw materials for the prepared high-strength piston aluminum alloy, by weight percentage, is as follows: Si: 11.5-12.0%, Cu: 4.35-4.55%, Ni: 2.2-2.6%, Mg: 1.0-1.15%, V: 0.08-0.11%, Ti: 0.08-0.11%, Zr: 0.06-0.09%, Fe: 0.3-0.4%, P: ≥0.0060%, with the remainder being Al.

2. The method for preparing a high-strength piston aluminum alloy according to claim 1, characterized in that, The Ca removal flux is FUSAL 1956.

3. The method for preparing a high-strength piston aluminum alloy according to claim 1, characterized in that, The refining agent is Pyroflux GR DR212.

4. The method for preparing a high-strength piston aluminum alloy according to claim 1, characterized in that, Step S3 includes the following sub-steps: S31. Casting and quenching treatment of aluminum piston skirt: The piston blank temperature shall not be less than 420℃. Take out the piston blank and immediately put it into the quenching box. The quenching position shall be with the stop facing downwards. The immersion depth shall not be lower than the center of the pin hole and not exceed the top of the pin hole. S32. Two aging treatments: The first aging is 180℃×5h, with the furnace temperature ≤50℃ and the heating time ≥45 minutes. After that, the furnace is removed and air-cooled to room temperature before the second aging is performed. The second aging is 245℃×2h, with the furnace temperature ≤50℃ and the heating time ≥60 minutes.

5. The method for preparing a high-strength piston aluminum alloy according to claim 4, characterized in that, In step S31, the quenching temperature is 60-90℃.

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