A low pressure casting solution heat treatment free aluminum alloy and a preparation method thereof

Abstract

The application belongs to the field of metal materials, and particularly relates to a low-pressure casting solid-solution-free heat treatment aluminum alloy and a preparation method thereof. The aluminum alloy comprises the following components in percentage by mass: Si 5-8%, Mg 0.1-0.6%, Cr 0.02-0.5%, Cu 0.1-1.5%, Zn 0.1-0.8%, Fe 0.1-0.5%, Ti 0.02-0.5%, Sr 0.005-0.03%, unavoidable impurities ≤0.03%, and the balance of Al. The aluminum alloy has higher tensile strength and yield strength than the commercially available A356 aluminum alloy, exhibits the advantages of high strength and excellent elongation, and has wide application range and good economic and social benefits.

Description

Technical Field

[0001] This application relates to the field of metallic materials, and more specifically, to a low-pressure casting solution-free heat-treated aluminum alloy and its preparation method. Background Technology

[0002] Aluminum alloys, with their advantages of light weight and high strength, are widely used in the automotive and aircraft manufacturing industries. With increasing awareness of environmental protection and energy conservation, lightweight materials and processes for automobiles are becoming increasingly essential. Lightweight materials are a primary means of achieving lightweighting, and safety is a prerequisite. While optimizing traditional structures, higher performance requirements are being placed on aluminum alloys, demanding not only high strength but also good ductility. Therefore, developing a low-pressure casting, solution-free heat-treatment-free aluminum alloy is crucial for the lightweighting development of the automotive, aircraft, and communications industries.

[0003] In related technologies, rare earth elements such as cobalt, vanadium, and manganese are often selected for aluminum alloys to improve their fluidity and toughness. However, rare earth elements and cobalt are expensive, and high-pressure casting is often required, resulting in high energy consumption. If low-pressure casting is used, solution heat treatment followed by artificial aging is necessary. For some precision workpieces, solution heat treatment can cause deformation, altering their original dimensions and reducing their yield. Furthermore, solution heat treatment lengthens the production cycle, increases energy consumption, and places a greater burden on enterprises. Summary of the Invention

[0004] In order to reduce energy consumption and shorten the production cycle of aluminum alloys, this application provides a low-pressure casting aluminum alloy without solution heat treatment and its preparation method.

[0005] In a first aspect, this application provides a low-pressure casting aluminum alloy that does not require solution heat treatment, employing the following technical solution:

[0006] A low-pressure casting aluminum alloy without solution heat treatment, comprising the following components by mass percentage: Si 5-8%, Mg 0.1-0.6%, Cr 0.02-0.5%, Cu 0.1-1.5%, Zn 0.1-0.8%, Fe 0.1-0.5%, Ti 0.02-0.5%, Sr 0.005-0.03%, unavoidable impurities ≤0.03%, and the balance being Al.

[0007] By adopting the above technical solution, the aluminum alloy castings of this application, through the synergistic effect between raw materials, achieve a tensile strength of 245-350MPa, a yield strength of 154-203MPa, and an elongation of 6.8-11.5%, exhibiting the advantages of high strength and excellent elongation. The tensile strength and yield strength are superior to those of commercially available A356 aluminum alloy, and it has a wide range of applications and good economic and social benefits.

[0008] Preferably, the total mass percentage of Cu, Mg, and Zn in the aluminum alloy composition is 0.7-1.8%.

[0009] By adopting the above technical solution, the proportions of various raw materials were optimized, further improving the tensile strength, yield strength, and elongation of the aluminum alloy.

[0010] Secondly, this application provides a method for preparing the aforementioned low-pressure casting solution-free heat-treated aluminum alloy, employing the following technical solution:

[0011] A method for preparing the above-mentioned low-pressure casting solution-free heat-treated aluminum alloy includes the following steps:

[0012] S1: Weigh and prepare materials according to the alloy composition ratio. Alloying elements are added in the form of pure alloys and intermediate alloys to obtain a mixture.

[0013] S2: Heat the mixture to 100~300℃, preheat for 5~10 minutes, then heat to 750~760℃ and hold for 15~25 minutes to obtain the first alloy liquid;

[0014] S3: Refining agent is added to the first alloy liquid for refining, and after degassing and impurity removal treatment, the second alloy liquid is obtained;

[0015] S4: Cast the second alloy liquid into shape to obtain an aluminum alloy.

[0016] By adopting the above technical solution, good strength can be achieved without solid solution heat treatment during the alloy preparation process, which solves the problem that most alloys can only achieve good performance after solid solution heat treatment.

[0017] Furthermore, in step S4, after casting, the aluminum alloy is subjected to a heat treatment at a temperature of 160-180℃ for 100-120 minutes to obtain the aluminum alloy.

[0018] Preferably, in step S1, Si is added in the form of Al-12Si alloy; Ti is added in the form of elemental or Al-5Ti-1B alloy; Sr is added in the form of elemental or Al-10Sr alloy; Cr is added in the form of elemental or Al-10Cr alloy; Fe is added in the form of elemental or Al-10Fe alloy; and Mg, Cu, and Zn are added in the form of elemental.

[0019] By adopting the above technical solution, Al-5Ti-B grain refiner is used to refine the grains during smelting, and Al-10Sr modifier is used to refine the eutectic silicon grains. The addition of Cu and Zn can refine the eutectic silicon to the submicron level, which greatly improves the strength and toughness of the aluminum alloy. At the same time, it can combine solid solution strengthening and dispersion strengthening to give the aluminum alloy excellent mechanical properties.

[0020] Preferably, in step S3, the refining temperature is 710~750℃ and the refining time is 20~50min.

[0021] By adopting the above technical solutions, the appropriate temperature range for refining can be controlled, saving energy while achieving better refining results.

[0022] Preferably, the refining agent is hexachloroethane, and the amount of refining agent added is 2-5% of the total weight of the first alloy liquid.

[0023] By adopting the above technical solutions, the amount of refining agent used can be reasonably controlled, thus saving raw material costs.

[0024] Preferably, in step S3, the degassing and impurity removal method is one or both of the following: rotary jet degassing method and ultrasonic degassing method.

[0025] By adopting the above technical solution, residual gas or impurities in the first alloy liquid are removed, the fineness of the product is improved, thereby enhancing the performance of the aluminum alloy.

[0026] Preferably, the gas required for the rotary jet degassing method is argon, with a gas pressure of 0.3~0.5MPa, a gas flow rate of 20~40L / min, and a time of 10~15min.

[0027] By adopting the above technical solution, the impurity gas in the first alloy liquid is reduced after rotary blowing degassing, which is beneficial to the subsequent process.

[0028] Preferably, the ultrasonic degassing method uses an ultrasonic frequency of 25~30kHz and a duration of 30~60s.

[0029] By adopting the above technical solution, ultrasonic degassing further improves the quality of the first alloy liquid, which is beneficial to the subsequent process.

[0030] Preferably, in step S4, the casting method is low-pressure casting, the temperature is 700~730℃, the injection pressure is 1~2 bar, and the holding pressure is 3~4 bar.

[0031] By adopting the above technical solutions, low-pressure casting and solution-free heat treatment greatly reduce energy consumption in the process and shorten the processing cycle, while the produced aluminum alloy has excellent mechanical properties.

[0032] In summary, this application has the following beneficial effects:

[0033] 1. This invention achieves low-pressure casting and solution-free heat treatment while ensuring excellent mechanical properties of the aluminum alloy, significantly reducing energy consumption and shortening the processing cycle. The low-pressure casting, solution-free heat-treated aluminum alloy of this invention exhibits significantly improved strength, with a tensile strength of 245-350 MPa and a yield strength of 154-203 MPa. This low-pressure casting, solution-free heat-treated aluminum alloy fully meets the requirements of the automotive, aerospace, and telecommunications industries for structural components with a tensile strength ≥240 MPa and an elongation ≥6%.

[0034] 2. This invention addresses existing Al-Si alloys by adding Cu, Mg, and Zn elements to form strengthening phases Mg2Si, Al2Cu, and MgZn2, which significantly improves the tensile strength and yield strength of the alloy without affecting its toughness. Good strength can be achieved without solution heat treatment during alloy preparation, solving the problem that most alloys currently require solution heat treatment to achieve good performance.

[0035] 3. In this invention, the Si element is selected at a dosage of 5-8% to keep the aluminum-silicon alloy in the hypoeutectic range, giving it good fluidity and filling ability, while also having good shrinkage, which can reduce the amount of material used for feeding and is suitable for large thin-walled parts and complex structural parts.

[0036] 4. In the aluminum alloy smelting process of the present invention, Al-Ti-B grain refiner is used to refine the grains, and Al-Sr modifier is used to refine the eutectic silicon grains. The addition of Cu and Zn can refine the eutectic silicon to the submicron level, which greatly improves the strength and toughness of the aluminum alloy. At the same time, it can combine solid solution strengthening and dispersion strengthening to give the aluminum alloy excellent mechanical properties.

[0037] 5. The aluminum alloy of this invention does not contain rare earth or cobalt, which are high-cost alloying elements, thus reducing the cost of the alloy and greatly improving its market competitiveness. Attached Figure Description

[0038] Figure 1 This is a microstructure diagram of Embodiment 1 of this application.

[0039] Figure 2This is a microstructure diagram of Embodiment 2 of this application.

[0040] Figure 3 This is a microstructure diagram of Embodiment 3 of this application. Detailed Implementation

[0041] The present application will be further described in detail below with reference to the embodiments. Example

[0042] Example 1

[0043] S1: Taking 25kg as an example, based on the following composition: Si 5%, Mg 0.4%, Cr 0.1%, Cu 0.8%, Zn 0.4%, Fe 0.1%, Ti 0.1%, Sr 0.01%, unavoidable impurities ≤0.03%, and the balance being Al, calculate the mass of the intermediate alloy, prepare the materials, and obtain the mixture.

[0044] Si was added in the form of Al-12Si alloy; Ti was added in the form of Al-5Ti-1B alloy; Sr was added in the form of Al-10Sr alloy; Cr was added in the form of Al-10Cr alloy; Fe was added in elemental form; and Mg, Cu, and Zn were added in elemental form.

[0045] S2: Heat the mixture to 300℃, preheat for 10 minutes, then heat to 760℃, melt the mixture and stir evenly, hold for 20 minutes to obtain the first alloy liquid.

[0046] S3: Hexachloroethane was added as a refining agent to the first alloy liquid for refining. The amount of hexachloroethane added was 3% of the total amount of the first alloy liquid. The refining temperature was 750℃, and the refining time was 30 min. After refining, argon gas was introduced to degas the rotor at a pressure of 0.5 MPa and a flow rate of 40 L / min for 15 min. Then, ultrasonic degassing and impurity removal were performed at a frequency of 25 kHz for 60 s. After standing for 5 min, the slag was removed to obtain the second alloy liquid.

[0047] S4: The second alloy liquid is placed into a J451 low-pressure casting machine for casting. The mold preheating temperature is 300℃, the injection pressure is 2 bar, the holding pressure is 3 bar, and the casting temperature is 730℃. Then, the temperature is cooled to 25℃, and then aged at 180℃ for 120 minutes to obtain the aluminum alloy. The aluminum alloy is in the form of a round bar with a diameter of 4cm and a length of 20cm.

[0048] Example 2

[0049] S1: Taking 25kg as an example, based on the following composition: Si 8.0%, Mg 0.6%, Cr 0.02%, Cu 0.1%, Zn 0.3%, Fe 0.1%, Ti 0.05%, Sr 0.03%, unavoidable impurities ≤0.03%, and the balance being Al, calculate the mass of the intermediate alloy, prepare the materials, and obtain the mixture.

[0050] Si was added in the form of Al-12Si alloy; Ti was added in the form of Al-5Ti-1B alloy; Sr was added in the form of Al-10Sr alloy; Cr was added in the form of Al-10Cr alloy; Fe was added in elemental form; and Mg, Cu, and Zn were added in elemental form.

[0051] S2: Heat the mixture to 100℃, preheat for 10 minutes, then heat to 750℃, melt the mixture and stir evenly, hold for 25 minutes to obtain the first alloy liquid.

[0052] S3: Hexachloroethane was added as a refining agent to the first alloy liquid for refining. The amount of hexachloroethane added was 1% of the total amount of the first alloy liquid. The refining temperature was 750℃, and the refining time was 20 min. After refining, argon gas was introduced to degas the rotor at a pressure of 0.4 MPa and a flow rate of 30 L / min for 10 min. Then, ultrasonic degassing and impurity removal were performed at a frequency of 25 kHz for 40 s. After standing for 5 min, the slag was removed to obtain the second alloy liquid.

[0053] S4: The second alloy liquid is placed into a J451 low-pressure casting machine for casting. The mold preheating temperature is 300℃, the injection pressure is 1.5 bar, the holding pressure is 3 bar, and the casting temperature is 730℃. Then, the temperature is cooled to 25℃, and then aged at 160℃ for 100 minutes to obtain the aluminum alloy. The aluminum alloy is in the form of a round bar with a diameter of 4cm and a length of 20cm.

[0054] Example 3

[0055] S1: Taking 25kg as an example, based on the following composition: Si 5.0%, Mg 0.1%, Cr 0.15%, Cu 1.0%, Zn 0.8%, Fe 0.5%, Ti 0.02%, Sr 0.005%, unavoidable impurities ≤0.03%, and the balance being Al, calculate the mass of the intermediate alloy, prepare the materials, and obtain the mixture.

[0056] Si is added in the form of Al-Si alloy; Ti is added in the form of elemental or Al-5Ti-1B alloy; Sr is added in the form of Al-10Sr alloy; Cr is added in the form of Al-10Cr alloy; Fe is added in the form of Al-10Fe alloy; Mg, Cu, and Zn are added in the form of elemental.

[0057] S2: Heat the mixture to 200℃, preheat for 5 minutes, then heat to 760℃, melt the mixture and stir evenly, hold for 15 minutes to obtain the first alloy liquid.

[0058] S3: Hexachloroethane was added as a refining agent to the first alloy liquid for refining. The amount of hexachloroethane added was 5% of the total amount of the first alloy liquid. The refining temperature was 710℃, and the refining time was 50 min. After refining, argon gas was introduced to degas the rotor at a pressure of 0.3 MPa and a flow rate of 40 L / min for 15 min. Then, ultrasonic degassing and impurity removal were performed at a frequency of 30 kHz for 40 s. After standing for 5 min, the slag was removed to obtain the second alloy liquid.

[0059] S4: The second alloy liquid is placed into a J451 low-pressure casting machine for casting. The mold preheating temperature is 300℃, the injection pressure is 2 bar, the holding pressure is 4 bar, and the casting temperature is 720℃. Then, the temperature is cooled to 25℃, and then aged at 180℃ for 100 minutes to obtain the aluminum alloy. The aluminum alloy is in the form of a round bar with a diameter of 4cm and a length of 20cm.

[0060] Example 4

[0061] S1: Taking 25kg as an example, based on the following composition: Si 7.0%, Mg 0.2%, Cr 0.5%, Cu 1.5%, Zn 0.1%, Fe 0.1%, Ti 0.05%, Sr 0.02%, unavoidable impurities ≤0.03%, and the balance being Al, calculate the mass of the intermediate alloy, prepare the materials, and obtain the mixture.

[0062] Si is added in the form of Al-Si alloy; Ti is added in the form of elemental or Al-5Ti-1B alloy; Sr is added in the form of Al-10Sr alloy; Cr is added in the form of Al-10Cr alloy; Fe is added in the form of Al-10Fe alloy; Mg, Cu, and Zn are added in the form of elemental.

[0063] S2: Heat the mixture to 300℃, preheat for 10 minutes, then heat to 750℃, melt the mixture and stir evenly, hold for 15 minutes to obtain the first alloy liquid.

[0064] S3: Hexachloroethane was added as a refining agent to the first alloy liquid for refining. The amount of hexachloroethane added was 2% of the total amount of the first alloy liquid. The refining temperature was 740℃, and the refining time was 30 min. After refining, argon gas was introduced to degas the rotor at a pressure of 0.5 MPa and a flow rate of 25 L / min for 10 min. Then, ultrasonic degassing and impurity removal were performed at a frequency of 30 kHz for 30 s. After standing for 5 min, the slag was removed to obtain the second alloy liquid.

[0065] S4: The second alloy liquid is placed into a J451 low-pressure casting machine for casting. The mold preheating temperature is 300℃, the injection pressure is 1.5 bar, the holding pressure is 3 bar, and the casting temperature is 730℃. Then, the temperature is reduced to 25℃ to obtain an aluminum alloy. The aluminum alloy is in the form of a round bar with a diameter of 4cm and a length of 20cm.

[0066] Example 5

[0067] S1: Taking 25kg as an example, based on the following composition: Si 7.0%, Mg 0.2%, Cr 0.05%, Cu 1.0%, Zn 0.1%, Fe 0.1%, Ti 0.05%, Sr 0.02%, unavoidable impurities ≤0.03%, and the balance being Al, calculate the mass of the intermediate alloy, prepare the materials, and obtain the mixture.

[0068] Si is added in the form of Al-Si alloy; Ti is added in the form of elemental or Al-5Ti-1B alloy; Sr is added in the form of Al-10Sr alloy; Cr is added in the form of Al-10Cr alloy; Fe is added in the form of Al-10Fe alloy; Mg, Cu, and Zn are added in the form of elemental.

[0069] S2: Heat the mixture to 250℃, preheat for 10 minutes, then heat to 760℃, melt the mixture and stir evenly, hold for 20 minutes to obtain the first alloy liquid.

[0070] S3: Hexachloroethane, a refining agent, is added to the first alloy liquid for refining. The amount of hexachloroethane added is 3% of the total volume of the first alloy liquid. The refining temperature is 750℃, and the refining time is 30 min. After refining, argon gas is introduced to degas the rotor at a pressure of 0.4 MPa and a flow rate of 30 L / min for 15 min. Then, ultrasonic degassing and impurity removal are performed at a frequency of 25 kHz for 30 s. After standing for 5 min, the slag is removed to obtain the second alloy liquid.

[0071] S4: The second alloy liquid is placed into a high-pressure casting machine for casting. The mold preheating temperature is 300℃, the clamping force is 200 tons, the injection pressure is 60MPa, the injection rate is 2.8m / s, and the casting temperature is 730℃. Then, the temperature is cooled to 25℃ to obtain an aluminum alloy. The aluminum alloy is in the form of a round bar with a diameter of 4cm and a length of 20cm.

[0072] Comparative Example

[0073] Comparative Example 1

[0074] An aluminum alloy, specifically a commercially available A356 aluminum alloy.

[0075] Performance testing

[0076] (1) The aluminum alloys obtained in Examples 1-3 were taken as samples, and their microstructure was observed using a scanning electron microscope. The microstructure of Example 1 is shown in [reference needed]. Figure 1 The microstructure of Example 2 is shown in [reference needed]. Figure 2 The microstructure of Example 3 is shown in [reference needed]. Figure 3 .

[0077] (2) The aluminum alloys obtained in Examples 1-5 and Comparative Example 1 were used as samples. The following performance tests were performed on the samples using a hardness tester and in accordance with GB / T228.1-2010. The average values ​​of the test results are shown in Table 1.

[0078] Table 1 Test Results

[0079]

[0080] As can be seen from Table 1, the aluminum alloy of the present invention has high tensile strength, ranging from 245 to 350 MPa, and also has high yield strength, ranging from 154 to 203 MPa. It also has good elongation, ranging from 6.8 to 11.5%, exhibiting the advantages of high strength and excellent elongation. It has a wide range of applications and good economic and social benefits.

[0081] The aluminum alloy of this invention achieves excellent strength and toughness after simple aging treatment without solution heat treatment. In conjunction with Example 4, low-pressure casting without aging treatment yields an aluminum alloy with superior tensile and yield strength compared to commercially available A356 aluminum alloy. Furthermore, in conjunction with Example 5, high-pressure casting without aging treatment also yields an aluminum alloy with excellent tensile and yield strength.

[0082] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A low-pressure casting aluminum alloy that does not require solution heat treatment, characterized in that: By mass percentage, the aluminum alloy comprises the following components: Si 5–8%, Mg 0.1–0.6%, Cr 0.02–0.5%, Cu 0.1–1.5%, Zn 0.1–0.8%, Fe 0.1–0.5%, Ti 0.02–0.5%, Sr 0.005–0.03%, unavoidable impurities ≤0.03%, and the balance being Al; furthermore, the total mass percentage of Cu, Mg, and Zn in the aluminum alloy composition is 0.7–1.8%. return Includes the following steps: S1: Weigh and prepare materials according to the alloy composition ratio. Alloying elements are added in the form of pure alloys and intermediate alloys to obtain a mixture. S2: Heat the mixture to 100~300℃, preheat for 5~10 minutes, then heat to 750~760℃ and hold for 15~25 minutes to obtain the first alloy liquid; S3: Refining agent is added to the first alloy liquid for refining, and after degassing and impurity removal treatment, the second alloy liquid is obtained; S4: Cast the second alloy liquid into shape to obtain an aluminum alloy.

2. A method for preparing a low-pressure casting solution-free heat-treated aluminum alloy as described in claim 1, characterized in that: In step S1, Si is added in the form of Al-12Si alloy; Ti is added in the form of elemental or Al-5Ti-1B alloy; Sr is added in the form of elemental or Al-10Sr alloy; Cr is added in the form of elemental or Al-10Cr alloy; Fe is added in the form of elemental or Al-10Fe alloy; Mg, Cu, and Zn are added in the form of elemental.

3. The method for preparing a low-pressure casting solution-free heat-treated aluminum alloy according to claim 2, characterized in that: In step S3, the refining temperature is 710~750℃ and the refining time is 20-50min.

4. The method for preparing a low-pressure casting aluminum alloy without solution heat treatment according to claim 2, characterized in that: The refining agent is hexachloroethane, and the amount of refining agent added is 2-5% of the total weight of the first alloy liquid.

5. The method for preparing a low-pressure casting aluminum alloy without solution heat treatment according to claim 2, characterized in that: In step S3, the degassing and impurity removal methods are one or both of the following: rotary jet degassing and ultrasonic degassing.

6. The method for preparing a low-pressure casting aluminum alloy without solution heat treatment according to claim 5, characterized in that: The gas required for the rotary jet degassing method is argon, with a gas pressure of 0.3~0.5MPa, a gas flow rate of 20~40L / min, and a time of 10~15min.

7. The method for preparing a low-pressure casting aluminum alloy without solution heat treatment according to claim 5, characterized in that: The ultrasonic degassing method uses an ultrasonic frequency of 25~30kHz and a duration of 30~60s.

8. The method for preparing a low-pressure casting aluminum alloy without solution heat treatment according to claim 2, characterized in that: In step S4, the casting method is low-pressure casting, the temperature is 700~730℃, the injection pressure is 1~2 bar, and the holding pressure is 3~4 bar.

Images