High-strength anti-cracking aluminum alloy and casting process thereof

Abstract

The high-strength anti-cracking aluminum alloy is prepared from the following components in percentage by mass: 4.2 to 5.8 percent of Si, 2.2 to 2.5 percent of Mg, 2.1 to 2.5 percent of Cu, 1.3 to 1.5 percent of Zn, 0.2 to 0.3 percent of Zr, 0.2 to 0.3 percent of V, 0.1 to 0.2 percent of Sb, 0.06 to 0.08 percent of Ta, 0.05 to 0.07 percent of Sn, 0.05 to 0.07 percent of Nb, 0.03 to 0.05 percent of Sr, 0.03 to 0.05 percent of Ce, 0.03 to 0.05 percent of Y, 0.02 to 0.03 percent of Yb, no more than 0.20 percent of other inevitable impurity elements in total and the balance of Al. The chemical components and the casting process are optimized, the strength of the aluminum alloy is greatly improved, cracks are reduced, and the aluminum alloy can be used for machining automobile hubs.

Description

Technical Field

[0001] This invention belongs to the field of aluminum alloy casting technology, specifically relating to a high-strength crack-resistant aluminum alloy and its casting process. Background Technology

[0002] With increasingly strong demands for lightweight and low-cost products, aluminum alloys are gaining more and more attention due to their significant advantages in both aspects. Aluminum alloys are alloys composed of aluminum as a base and other elements, and are commonly used materials in structural engineering. Aluminum alloys possess advantages such as low density, high specific strength, high specific stiffness, good thermal conductivity, good electrical conductivity, excellent processing performance, environmental friendliness, and recyclability, making them widely used in many fields including automotive, aerospace, chemical, shipbuilding, and electronics.

[0003] Die-cast aluminum alloys are aluminum alloys obtained through pressure casting. They can be used to produce complex-shaped workpieces, achieving one-time molding of complex structures, and have significant advantages in terms of process simplicity and operability. Aluminum-silicon and aluminum-magnesium alloys are the most common die-cast aluminum alloys. Aluminum-silicon die-cast parts often exhibit graying or blackening of the surface after chemical treatment, and have poor mechanical properties and high brittleness. Aluminum-magnesium die-cast parts have poor die-casting performance, easily exhibiting defects such as sticking, hot cracking, incomplete filling, cold shuts, and porosity, and also have low mechanical properties and hardness. Overall, traditional die-cast aluminum alloys have poor anodizing performance, low strength, poor corrosion resistance, and their fluidity cannot meet the material requirements of the products. During the smelting process of aluminum and its alloys, contaminants such as alumina and hydrogen are present, affecting the purity of the melt and leading to defects such as bubbles, porosity, inclusions, and porosity in the ingots. These defects make the ingots very prone to deformation and even fracture, failing to meet the working requirements of mechanical parts that need to withstand large dynamic loads.

[0004] In recent years, with the rapid development of the automotive industry, the application of aluminum alloy wheels has become increasingly common. Compared with steel wheels, aluminum alloy wheels significantly reduce non-load-bearing weight, thereby improving grip, acceleration, and braking performance, and increasing rigidity. The high hardness of aluminum wheels significantly reduces tire or wheel tilt during cornering, improving the cooling effect of the braking system. Furthermore, some metals in aluminum alloys are excellent heat conductors, facilitating the rapid release of heat generated during braking and reducing brake failure due to overheating. Moreover, the greater flexibility in the design of aluminum alloy wheels allows for more effective cooling through airflow directed into the braking system. However, aluminum alloys are brittle and prone to small, easily visible cracks, and their strength is not as high as that of steel. Therefore, improving existing aluminum alloy casting processes is essential to meet the application requirements of automotive wheels.

[0005] Patent CN102676885B discloses an aluminum alloy ingot with added strontium, which effectively improves the strength and toughness of the ingot. Furthermore, the addition of titanium and boron elements enables excellent grain refinement in the die-cast product, effectively overcoming casting cracks, improving the appearance of the casting, and enhancing the surface quality of the ingot. In particular, it reduces cold shuts in the ingot and effectively increases the impact toughness of the aluminum alloy ingot by 15%–20% without compromising strength. This patented technology primarily optimizes performance through adjustments to the chemical element composition, but in practice, its improvement on the performance of aluminum alloys is very limited. Summary of the Invention

[0006] In view of the shortcomings of the existing technology, the purpose of this invention is to provide a high-strength crack-resistant aluminum alloy and its casting process.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] A high-strength, crack-resistant aluminum alloy is composed of the following components by mass percentage: Si 4.2–5.8%, Mg 2.2–2.5%, Cu 2.1–2.5%, Zn 1.3–1.5%, Zr 0.2–0.3%, V 0.2–0.3%, Sb 0.1–0.2%, Ta 0.06–0.08%, Sn 0.05–0.07%, Nb 0.05–0.07%, Sr 0.03–0.05%, Ce 0.03–0.05%, Y 0.03–0.05%, Yb 0.02–0.03%, with the total content of other unavoidable impurity elements not exceeding 0.20%, and the balance being Al.

[0009] Preferably, the content of any other unavoidable impurity element is no more than 0.04%.

[0010] The casting process for the aforementioned high-strength, crack-resistant aluminum alloy comprises the following specific steps:

[0011] (1) First, high-purity niobium powder, high-purity strontium powder, high-purity cerium powder, high-purity yttrium powder, and high-purity ytterbium powder are used as raw materials, and intermediate alloy powder is prepared by discharge plasma sintering;

[0012] (2) Then add the pure aluminum ingot into the preheated melting furnace, heat it to 800-850℃, keep it at the temperature for 30-40 minutes, and then add high-purity silicon powder, high-purity magnesium powder, high-purity copper powder, high-purity zinc powder, high-purity zirconium powder, high-purity vanadium powder, high-purity antimony powder, high-purity tantalum powder and high-purity tin powder under stirring conditions, keep it at the temperature and stir for 40-50 minutes, continue to add intermediate alloy powder, keep it at the temperature and stir for 20-30 minutes, cool it down to 730-750℃ to obtain aluminum alloy melt, refine it, let it stand, die-cast it, demold it to obtain die-cast parts;

[0013] (3) The die casting is subjected to supersonic particle bombardment, pulsed laser treatment, deep cryogenic treatment, aging treatment and air cooling in sequence to obtain the high-strength crack-resistant aluminum alloy.

[0014] Preferably, in step (1), the intermediate alloy powder is prepared by the following method: mixing and ball milling high-purity niobium powder, high-purity strontium powder, high-purity cerium powder, high-purity yttrium powder and high-purity ytterbium powder to obtain mixed powder, sintering by discharge plasma, and pulverizing and sieving to obtain the powder.

[0015] More preferably, 10mm diameter zirconia balls are used during ball milling, the ball-to-material ratio (mass) is 7-9:1, the ball milling speed is 60-80 r / min, and the ball milling time is 7-9 hours.

[0016] Further preferred, the discharge plasma sintering conditions are: temperature 1050~1100℃, pressure 70~80MPa, and time 20~30 minutes.

[0017] More preferably, the particle size of the obtained intermediate alloy powder is less than 10 μm.

[0018] Preferably, in step (2), sodium chloride is added for refining. The amount of sodium chloride is 0.3% of the mass of the aluminum alloy melt. The refining temperature is 730-750℃, the refining time is 10-15 minutes, argon gas is introduced for degassing refining, and the refining is completed after the composition is tested and found to be qualified.

[0019] Preferably, in step (2), the temperature is allowed to drop to 680-690°C.

[0020] Preferably, in step (2), the die-casting method is as follows: molten aluminum alloy is injected into a mold preheated to 230-240°C. At the beginning of filling, the flow rate of molten aluminum alloy is controlled at 0.4-0.5 m / s, and the casting pressure is 50-55 MPa. When the filling rate reaches 55-60%, the flow rate of molten aluminum alloy is controlled at 1.8-2 m / s, and the casting pressure is 68-72 MPa. After die-casting, the pressure is held for 100-120 seconds, the pressure is released, and the mold is demolded.

[0021] Preferably, the die-cast part obtained in step (2) is cylindrical with a diameter of 50-55cm and a height of 25-30cm.

[0022] Preferably, in step (3), α-Al₂O₃ with a particle size of 30–40 μm is used for supersonic particle bombardment. The specific conditions are: nitrogen as the carrier gas, 90° injection angle, 30–35 mm distance between the nozzle and the sample, 1–2 MPa injection pressure of the carrier gas, and 3–4 s / cm bombardment time. 2 .

[0023] Preferably, in step (3), the pulsed laser processing conditions are: laser wavelength 360-365nm, laser spot diameter 1-2mm, average laser energy 0.8-1W, frequency 40-45kHz, and laser marking rate 300-350mm / s.

[0024] Preferably, in step (3), the specific method of cryogenic treatment is to immerse the die-casting part in liquid nitrogen at -197℃ for 6 to 8 hours.

[0025] Preferably, in step (3), the aging treatment temperature is 170-190℃ and the aging treatment time is 3-4 hours.

[0026] The aforementioned application of a high-strength, crack-resistant aluminum alloy in automobile wheel hubs.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] This invention provides a high-strength, crack-resistant aluminum alloy and its casting process, composed of the following components by mass percentage: Si 4.2–5.8%, Mg 2.2–2.5%, Cu 2.1–2.5%, Zn 1.3–1.5%, Zr 0.2–0.3%, V 0.2–0.3%, Sb 0.1–0.2%, Ta 0.06–0.08%, Sn 0.05–0.07%, Nb 0.05–0.07%, Sr 0.03–0.05%, Ce 0.03–0.05%, Y 0.03–0.05%, Yb 0.02–0.03%, with the total content of other unavoidable impurity elements not exceeding 0.20%, and the balance being Al. This invention optimizes the chemical composition and casting process, significantly improving the strength of the aluminum alloy and reducing crack formation, making it suitable for automotive wheel hub processing.

[0029] The applicant stabilized grain boundaries, reduced grain coarsening, and refined the eutectic structure by optimizing and adjusting the chemical composition, thereby ensuring high strength of the aluminum alloy and reducing crack formation.

[0030] In the casting and processing of aluminum alloys, high-purity niobium powder, high-purity strontium powder, high-purity cerium powder, high-purity yttrium powder, and high-purity ytterbium powder are first used as raw materials and sintered by discharge plasma to prepare intermediate alloy powder. Then, pure aluminum ingots are added to a preheated melting furnace and heated to 800-850℃, held for 30-40 minutes. Next, high-purity silicon powder, high-purity magnesium powder, high-purity copper powder, high-purity zinc powder, high-purity zirconium powder, high-purity vanadium powder, high-purity antimony powder, high-purity tantalum powder, and high-purity tin powder are added under stirring conditions, and the mixture is held and stirred for 40-50 minutes. The intermediate alloy powder is then added, and the mixture is held and stirred for 20-30 minutes. The temperature is then lowered to 730-750℃ to obtain aluminum alloy melt. This melt is then refined, allowed to stand, die-cast, and demolded to obtain a die-cast part. The die-cast part is then subjected to supersonic particle bombardment, pulsed laser treatment, deep cryogenic treatment, aging treatment, and air cooling to obtain the final product. The casting process of this invention effectively removes gas and inclusions from the molten aluminum alloy, improves the purity of the molten metal, and, combined with the post-treatment of the die-cast parts, further improves the strength of the aluminum alloy and reduces the generation of cracks. Detailed Implementation

[0031] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0032] Unless otherwise specified, all products in this invention were purchased through market channels.

[0033] Example 1

[0034] A high-strength, crack-resistant aluminum alloy is composed of the following components by mass percentage: Si 4.2%, Mg 2.2%, Cu 2.1%, Zn 1.3%, Zr 0.2%, V 0.2%, Sb 0.1%, Ta 0.06%, Sn 0.05%, Nb 0.05%, Sr 0.03%, Ce 0.03%, Y 0.03%, Yb 0.02%, with the total content of other unavoidable impurity elements not exceeding 0.20%, and the balance being Al.

[0035] Other unavoidable impurity elements have a single component content of no more than 0.04%.

[0036] The casting process for the aforementioned high-strength, crack-resistant aluminum alloy comprises the following specific steps:

[0037] (1) First, high-purity niobium powder, high-purity strontium powder, high-purity cerium powder, high-purity yttrium powder, and high-purity ytterbium powder are used as raw materials, and intermediate alloy powder is prepared by discharge plasma sintering;

[0038] (2) Then add the pure aluminum ingot into the preheated melting furnace, heat it to 800°C, keep it at that temperature for 30 minutes, and then add high-purity silicon powder, high-purity magnesium powder, high-purity copper powder, high-purity zinc powder, high-purity zirconium powder, high-purity vanadium powder, high-purity antimony powder, high-purity tantalum powder and high-purity tin powder under stirring conditions. Keep it at that temperature and stir for 40 minutes, then add intermediate alloy powder, keep it at that temperature and stir for 20 minutes, and then cool it down to 730°C to obtain aluminum alloy melt. Refine it, let it stand, die-cast it, demold it, and obtain the die-cast part.

[0039] (3) The die casting is subjected to supersonic particle bombardment, pulsed laser treatment, deep cryogenic treatment, aging treatment and air cooling in sequence to obtain the high-strength crack-resistant aluminum alloy.

[0040] In step (1), the intermediate alloy powder is prepared by the following method: high-purity niobium powder, high-purity strontium powder, high-purity cerium powder, high-purity yttrium powder and high-purity ytterbium powder are mixed and ball-milled to obtain a mixed powder, which is then sintered by discharge plasma, pulverized and sieved to obtain the final product.

[0041] The ball milling process used 10mm diameter zirconia balls with a ball-to-material ratio (mass) of 7:1, a milling speed of 60r / min, and a milling time of 7 hours.

[0042] The conditions for discharge plasma sintering were: temperature 1050℃, pressure 70MPa, and time 20 minutes.

[0043] The resulting intermediate alloy powder has a particle size of less than 10 μm.

[0044] In step (2), sodium chloride is added for refining. The amount of sodium chloride is 0.3% of the mass of the aluminum alloy melt. The refining temperature is 730℃ and the refining time is 10 minutes. Argon gas is introduced for degassing and refining. The refining is completed after the composition is tested and found to be qualified.

[0045] In step (2), the mixture is left to stand until the temperature drops to 680°C.

[0046] In step (2), the die casting method is as follows: the molten aluminum alloy is injected into the mold preheated to 230°C. When the filling begins, the flow rate of the molten aluminum alloy is controlled at 0.4 m / s and the casting pressure is 50 MPa. When the filling rate reaches 55%, the flow rate of the molten aluminum alloy is controlled at 1.8 m / s and the casting pressure is 68 MPa. After the die casting is completed, the pressure is held for 100 seconds, the pressure is released, and the mold is demolded.

[0047] The die-cast part obtained in step (2) is cylindrical, with a diameter of 50cm and a height of 25cm.

[0048] In step (3), supersonic particle bombardment was performed using α-Al₂O₃ with a particle size of 30 μm. The specific conditions were: nitrogen as the carrier gas, a 90° injection angle, a 30 mm distance between the nozzle and the sample, a 1 MPa injection carrier gas pressure, and a bombardment time of 3 s / cm.2 .

[0049] In step (3), the pulsed laser processing conditions are: laser wavelength 360nm, laser spot diameter 1mm, average laser energy 0.8W, frequency 40kHz, and laser marking rate 300mm / s.

[0050] In step (3), the specific method of cryogenic treatment is as follows: immerse the die-casting part in liquid nitrogen at -197℃ and cryogenically treat it for 6 hours.

[0051] In step (3), the aging treatment temperature is 170℃ and the aging treatment time is 3 hours.

[0052] Example 2

[0053] A high-strength, crack-resistant aluminum alloy is composed of the following components by mass percentage: Si 5.8%, Mg 2.5%, Cu 2.5%, Zn 1.5%, Zr 0.3%, V 0.3%, Sb 0.2%, Ta 0.08%, Sn 0.07%, Nb 0.07%, Sr 0.05%, Ce 0.05%, Y 0.05%, Yb 0.03%, with the total content of other unavoidable impurity elements not exceeding 0.20%, and the balance being Al.

[0054] Other unavoidable impurity elements have a single component content of no more than 0.04%.

[0055] The casting process for the aforementioned high-strength, crack-resistant aluminum alloy comprises the following specific steps:

[0056] (1) First, high-purity niobium powder, high-purity strontium powder, high-purity cerium powder, high-purity yttrium powder, and high-purity ytterbium powder are used as raw materials, and intermediate alloy powder is prepared by discharge plasma sintering;

[0057] (2) Then add the pure aluminum ingot into the preheated melting furnace, heat it to 850°C, keep it at that temperature for 40 minutes, and then add high-purity silicon powder, high-purity magnesium powder, high-purity copper powder, high-purity zinc powder, high-purity zirconium powder, high-purity vanadium powder, high-purity antimony powder, high-purity tantalum powder and high-purity tin powder under stirring conditions. Keep it at that temperature and stir for 50 minutes, then add intermediate alloy powder, keep it at that temperature and stir for 30 minutes, and then cool it down to 750°C to obtain aluminum alloy melt. Refine it, let it stand, die-cast it, demold it, and obtain the die-cast part.

[0058] (3) The die casting is subjected to supersonic particle bombardment, pulsed laser treatment, deep cryogenic treatment, aging treatment and air cooling in sequence to obtain the high-strength crack-resistant aluminum alloy.

[0059] In step (1), the intermediate alloy powder is prepared by the following method: high-purity niobium powder, high-purity strontium powder, high-purity cerium powder, high-purity yttrium powder and high-purity ytterbium powder are mixed and ball-milled to obtain a mixed powder, which is then sintered by discharge plasma, pulverized and sieved to obtain the final product.

[0060] The ball milling process used 10mm diameter zirconia balls with a ball-to-material ratio (mass) of 9:1, a milling speed of 80r / min, and a milling time of 9 hours.

[0061] The conditions for discharge plasma sintering were: temperature 1100℃, pressure 80MPa, and time 30 minutes.

[0062] The resulting intermediate alloy powder has a particle size of less than 10 μm.

[0063] In step (2), sodium chloride is added for refining. The amount of sodium chloride is 0.3% of the mass of the aluminum alloy melt. The refining temperature is 750℃ and the refining time is 15 minutes. Argon gas is introduced for degassing and refining. The refining is completed after the composition is tested and found to be qualified.

[0064] In step (2), the mixture is left to stand until the temperature drops to 690°C.

[0065] In step (2), the die casting method is as follows: the aluminum alloy melt is injected into the mold preheated to 240°C. When the filling begins, the flow rate of the aluminum alloy melt is controlled at 0.5 m / s and the casting pressure is 55 MPa. When the filling rate reaches 60%, the flow rate of the aluminum alloy melt is controlled at 2 m / s and the casting pressure is 72 MPa. After the die casting is completed, the pressure is held for 120 seconds, the pressure is released, and the mold is demolded.

[0066] The die-cast part obtained in step (2) is cylindrical, with a diameter of 55cm and a height of 30cm.

[0067] In step (3), α-Al₂O₃ particles with a diameter of 40 μm were used for supersonic particle bombardment. The specific conditions were: nitrogen as the carrier gas, a spray angle of 90°, a distance of 35 mm between the nozzle and the sample, a spray carrier gas pressure of 2 MPa, and a bombardment time of 4 s / cm. 2 .

[0068] In step (3), the pulsed laser processing conditions are: laser wavelength 365nm, laser spot diameter 2mm, average laser energy 1W, frequency 45kHz, and laser marking rate 350mm / s.

[0069] In step (3), the specific method of cryogenic treatment is as follows: immerse the die-casting part in liquid nitrogen at -197℃ and cryogenically treat it for 8 hours.

[0070] In step (3), the aging treatment temperature is 190℃ and the aging treatment time is 4 hours.

[0071] Example 3

[0072] A high-strength, crack-resistant aluminum alloy is composed of the following components by mass percentage: Si 5.1%, Mg 2.3%, Cu 2.2%, Zn 1.4%, Zr 0.25%, V 0.25%, Sb 0.15%, Ta 0.07%, Sn 0.06%, Nb 0.06%, Sr 0.04%, Ce 0.04%, Y 0.04%, Yb 0.02%, with the total content of other unavoidable impurity elements not exceeding 0.20%, and the balance being Al.

[0073] Other unavoidable impurity elements have a single component content of no more than 0.04%.

[0074] The casting process for the aforementioned high-strength, crack-resistant aluminum alloy comprises the following specific steps:

[0075] (1) First, high-purity niobium powder, high-purity strontium powder, high-purity cerium powder, high-purity yttrium powder, and high-purity ytterbium powder are used as raw materials, and intermediate alloy powder is prepared by discharge plasma sintering;

[0076] (2) Then add the pure aluminum ingot into the preheated melting furnace, heat it to 820°C, keep it at that temperature for 35 minutes, and then add high-purity silicon powder, high-purity magnesium powder, high-purity copper powder, high-purity zinc powder, high-purity zirconium powder, high-purity vanadium powder, high-purity antimony powder, high-purity tantalum powder and high-purity tin powder under stirring conditions. Keep it at that temperature and stir for 45 minutes, then add intermediate alloy powder, keep it at that temperature and stir for 25 minutes, and then cool it down to 740°C to obtain aluminum alloy melt. Refine it, let it stand, die-cast it, demold it, and obtain the die-cast part.

[0077] (3) The die casting is subjected to supersonic particle bombardment, pulsed laser treatment, deep cryogenic treatment, aging treatment and air cooling in sequence to obtain the high-strength crack-resistant aluminum alloy.

[0078] In step (1), the intermediate alloy powder is prepared by the following method: high-purity niobium powder, high-purity strontium powder, high-purity cerium powder, high-purity yttrium powder and high-purity ytterbium powder are mixed and ball-milled to obtain a mixed powder, which is then sintered by discharge plasma, pulverized and sieved to obtain the final product.

[0079] During ball milling, 10mm diameter zirconia balls were used, the ball-to-material ratio (by mass) was 8:1, the ball milling speed was 70r / min, and the ball milling time was 8 hours.

[0080] The conditions for discharge plasma sintering were: temperature 1080℃, pressure 75MPa, and time 25 minutes.

[0081] The resulting intermediate alloy powder has a particle size of less than 10 μm.

[0082] In step (2), sodium chloride is added for refining. The amount of sodium chloride is 0.3% of the mass of the aluminum alloy melt. The refining temperature is 740℃ and the refining time is 12 minutes. Argon gas is introduced for degassing and refining. The refining is completed after the composition is tested and found to be qualified.

[0083] In step (2), the mixture is left to stand until the temperature drops to 685°C.

[0084] In step (2), the die casting method is as follows: the aluminum alloy melt is injected into the mold preheated to 235°C. When the filling begins, the flow rate of the aluminum alloy melt is controlled at 0.4 m / s and the casting pressure is 52 MPa. When the filling rate reaches 58%, the flow rate of the aluminum alloy melt is controlled at 1.9 m / s and the casting pressure is 70 MPa. After the die casting is completed, the pressure is held for 110 seconds, the pressure is released, and the mold is demolded.

[0085] The die-cast part obtained in step (2) is cylindrical, with a diameter of 52cm and a height of 28cm.

[0086] In step (3), supersonic particle bombardment was performed using α-Al₂O₃ with a particle size of 35 μm. The specific conditions were: nitrogen as the carrier gas, a spray angle of 90°, a distance of 32 mm between the nozzle and the sample, a spray carrier gas pressure of 1.5 MPa, and a bombardment time of 4 s / cm. 2 .

[0087] In step (3), the pulsed laser processing conditions are: laser wavelength 365nm, laser spot diameter 2mm, average laser energy 0.9W, frequency 42kHz, and laser marking rate 330mm / s.

[0088] In step (3), the specific method of cryogenic treatment is as follows: immerse the die-casting part in liquid nitrogen at -197℃ for 7 hours.

[0089] In step (3), the aging treatment temperature is 180℃ and the aging treatment time is 3 hours.

[0090] Comparative Example 1

[0091] Nb in the chemical composition is omitted;

[0092] The rest is the same as in Example 1.

[0093] Comparative Example 2

[0094] Yb is omitted from the chemical composition;

[0095] The rest is the same as in Example 1.

[0096] Comparative Example 3

[0097] An aluminum alloy is composed of the following components in mass percentage: Si 4.2%, Mg 2.2%, Cu 2.1%, Zn 1.3%, Zr 0.2%, V 0.2%, Sb 0.1%, Ta 0.06%, Sn 0.05%, Nb 0.05%, Sr 0.03%, Ce 0.03%, Y 0.03%, Yb 0.02%, with the total content of other unavoidable impurity elements not exceeding 0.20%, and the balance being Al.

[0098] Other unavoidable impurity elements have a single component content of no more than 0.04%.

[0099] The specific steps of the aforementioned aluminum alloy casting process are as follows:

[0100] (1) Add pure aluminum ingots to a preheated melting furnace, heat to 800°C, keep warm for 30 minutes, then add high-purity silicon powder, high-purity magnesium powder, high-purity copper powder, high-purity zinc powder, high-purity zirconium powder, high-purity vanadium powder, high-purity antimony powder, high-purity tantalum powder, and high-purity tin powder under stirring conditions, keep warm and stir for 40 minutes, then add high-purity niobium powder, high-purity strontium powder, high-purity cerium powder, high-purity yttrium powder, and high-purity ytterbium powder, keep warm and stir for 20 minutes, cool down to 730°C to obtain aluminum alloy melt, refine, let stand, die-cast, demold, and obtain die-cast parts;

[0101] (2) The die casting is subjected to supersonic particle bombardment, pulsed laser treatment, deep cryogenic treatment, aging treatment and air cooling in sequence to obtain the aluminum alloy mentioned above.

[0102] In step (1), sodium chloride is added for refining. The amount of sodium chloride is 0.3% of the mass of the aluminum alloy melt. The refining temperature is 730℃ and the refining time is 10 minutes. Argon gas is introduced for degassing and refining. The refining is completed after the composition is tested and found to be qualified.

[0103] In step (1), the mixture is left to stand until the temperature drops to 680°C.

[0104] In step (1), the die casting method is as follows: the molten aluminum alloy is injected into the mold preheated to 230°C. When the filling begins, the flow rate of the molten aluminum alloy is controlled at 0.4 m / s and the casting pressure is 50 MPa. When the filling rate reaches 55%, the flow rate of the molten aluminum alloy is controlled at 1.8 m / s and the casting pressure is 68 MPa. After the die casting is completed, the pressure is held for 100 seconds, the pressure is released, and the mold is demolded.

[0105] The die-cast part obtained in step (1) is cylindrical, with a diameter of 50cm and a height of 25cm.

[0106] In step (2), supersonic particle bombardment was performed using α-Al₂O₃ with a particle size of 30 μm. The specific conditions were: nitrogen as the carrier gas, a 90° injection angle, a 30 mm distance between the nozzle and the sample, a 1 MPa injection carrier gas pressure, and a bombardment time of 3 s / cm. 2 .

[0107] In step (2), the pulsed laser processing conditions are: laser wavelength 360nm, laser spot diameter 1mm, average laser energy 0.8W, frequency 40kHz, and laser marking rate 300mm / s.

[0108] In step (2), the specific method of cryogenic treatment is as follows: immerse the die-casting part in liquid nitrogen at -197℃ for 6 hours.

[0109] In step (2), the aging treatment temperature is 170℃ and the aging treatment time is 3 hours.

[0110] Comparative Example 4

[0111] Supersonic particle bombardment is omitted;

[0112] The rest is the same as in Example 1.

[0113] Comparative Example 5

[0114] Pulse laser processing is omitted;

[0115] The rest is the same as in Example 1.

[0116] Comparative Example 6

[0117] Cryotherapy is omitted;

[0118] The rest is the same as in Example 1.

[0119] The aluminum alloys obtained in Examples 1-3 and Comparative Examples 1-6 were subjected to performance tests, including:

[0120] 1. Mechanical property testing: The elongation and yield strength were tested using an electronic universal testing machine (DM8000-B, Yangzhou Dongming Testing Instruments).

[0121] 2. Pinhole: The pinhole of aluminum alloys is examined in accordance with GB / T 10851-2021 "Method for evaluating the pinhole of cast aluminum alloys".

[0122] 3. Crack resistance: Visually inspect the cracks on the aluminum alloy surface, and observe the cracks again after heating at 350℃ for 2 hours.

[0123] The test results are shown in Table 1.

[0124] Table 1. Performance Test Results

[0125]

[0126] As shown in Table 1, the aluminum alloys obtained in Examples 1 to 3 have excellent mechanical properties, high strength, and no cracks.

[0127] Comparative Example 1 omitted Nb in its chemical composition, Comparative Example 2 omitted Yb, Comparative Example 3 did not prepare intermediate alloy powder, Comparative Example 4 omitted supersonic particle bombardment, Comparative Example 5 omitted pulsed laser treatment, and Comparative Example 6 omitted cryogenic treatment. The strength of the aluminum alloy was significantly reduced, and cracks appeared. This shows that the chemical composition, preparation of intermediate alloy powder, and specific post-treatment methods of the present invention work synergistically to improve the performance of aluminum alloy.

[0128] The present invention has been illustrated through the above embodiments, but the present invention is not limited to the above embodiments, that is, it does not mean that the present invention must rely on the above embodiments to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions of individual raw materials in the product of the present invention, addition of auxiliary components, selection of specific methods, etc., are all within the protection scope and disclosure scope of the present invention.

Claims

1. A high-strength, crack-resistant aluminum alloy, characterized in that, It is composed of the following components by mass percentage: Si 4.2–5.8%, Mg 2.2–2.5%, Cu 2.1–2.5%, Zn 1.3–1.5%, Zr 0.2–0.3%, V 0.2–0.3%, Sb 0.1–0.2%, Ta 0.06–0.08%, Sn 0.05–0.07%, Nb 0.05–0.07%, Sr 0.03–0.05%, Ce 0.03–0.05%, Y 0.03–0.05%, Yb 0.02–0.03%, and other unavoidable impurity elements totaling no more than 0.20%, with the balance being Al.

2. The casting process for a high-strength, crack-resistant aluminum alloy as described in claim 2, characterized in that, The specific steps are as follows: (1) First, high-purity niobium powder, high-purity strontium powder, high-purity cerium powder, high-purity yttrium powder, and high-purity ytterbium powder are used as raw materials, and intermediate alloy powder is prepared by discharge plasma sintering; (2) Then add the pure aluminum ingot into the preheated melting furnace, heat it to 800-850℃, keep it at the temperature for 30-40 minutes, and then add high-purity silicon powder, high-purity magnesium powder, high-purity copper powder, high-purity zinc powder, high-purity zirconium powder, high-purity vanadium powder, high-purity antimony powder, high-purity tantalum powder and high-purity tin powder under stirring conditions, keep it at the temperature and stir for 40-50 minutes, continue to add intermediate alloy powder, keep it at the temperature and stir for 20-30 minutes, cool it down to 730-750℃ to obtain aluminum alloy melt, refine it, let it stand, die-cast it, demold it to obtain die-cast parts; (3) The die casting is subjected to supersonic particle bombardment, pulsed laser treatment, deep cryogenic treatment, aging treatment and air cooling in sequence to obtain the high-strength crack-resistant aluminum alloy.

3. The casting process according to claim 2, characterized in that, In step (1), the intermediate alloy powder is prepared by the following method: high-purity niobium powder, high-purity strontium powder, high-purity cerium powder, high-purity yttrium powder and high-purity ytterbium powder are mixed and ball-milled to obtain a mixed powder, which is then sintered by discharge plasma, pulverized and sieved to obtain the final product.

4. The casting process according to claim 2, characterized in that, In step (2), sodium chloride is added for refining. The amount of sodium chloride is 0.3% of the mass of the aluminum alloy melt. The refining temperature is 730-750℃ and the refining time is 10-15 minutes. Argon gas is introduced for degassing and refining. The refining is completed after the composition is found to be qualified.

5. The casting process according to claim 2, characterized in that, In step (2), the die-casting method is as follows: molten aluminum alloy is injected into a mold preheated to 230-240°C. At the beginning of filling, the flow rate of molten aluminum alloy is controlled at 0.4-0.5 m / s, and the casting pressure is 50-55 MPa. When the filling rate reaches 55-60%, the flow rate of molten aluminum alloy is controlled at 1.8-2 m / s, and the casting pressure is 68-72 MPa. After die-casting, the pressure is held for 100-120 seconds, the pressure is released, and the mold is demolded.

6. The casting process according to claim 2, characterized in that, In step (3), supersonic particle bombardment is performed using α-Al₂O₃ with a particle size of 30–40 μm. The specific conditions are: nitrogen as the carrier gas, a 90° injection angle, a distance of 30–35 mm between the nozzle and the sample, an injection carrier gas pressure of 1–2 MPa, and a bombardment time of 3–4 s / cm. 2 .

7. The casting process according to claim 2, characterized in that, In step (3), the pulsed laser processing conditions are: laser wavelength 360-365nm, laser spot diameter 1-2mm, average laser energy 0.8-1W, frequency 40-45kHz, and laser marking rate 300-350mm / s.

8. The casting process according to claim 2, characterized in that, In step (3), the specific method of cryogenic treatment is to immerse the die-casting part in liquid nitrogen at -197℃ for 6 to 8 hours.

9. The casting process according to claim 2, characterized in that, In step (3), the aging treatment temperature is 170-190℃ and the aging treatment time is 3-4 hours.

10. The application of the high-strength crack-resistant aluminum alloy as described in claim 1 in automobile wheel hubs.

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