A casting aluminum alloy modifier and a preparation process thereof

Abstract

The application provides a casting aluminum alloy modifier and a preparation process thereof, material components of the casting aluminum alloy modifier include Sb, Ti, B, V, La-Ce mixed rare earth and trace elements Be and Hf, and the preparation process includes smelting, refining, continuous rolling and test verification steps. The raw material and the preparation process of the casting aluminum alloy modifier provided by the application avoid the quality problems of aluminum alloy caused by the addition of Na, P and Sr elements in the aluminum alloy modifier, effectively improve the modification effect of the structure and performance of the casting aluminum alloy, improve the room temperature mechanical properties of the casting aluminum alloy, help to reduce the production cost, improve the production efficiency and product quality, realize batch production and high automation.

Description

Technical Field

[0001] This invention relates to the field of cast aluminum alloy technology, and in particular to a cast aluminum alloy modifier and its preparation process. Background Technology

[0002] Cast aluminum alloys possess excellent casting properties and are the most widely used aluminum alloy material in automobiles. Among them, aluminum-silicon alloys are the most extensively used, accounting for approximately 80% to 90% of the total cast aluminum alloy usage. Almost all aluminum alloy castings undergo one or more melting and solidification processes during their production. The quality of the alloy melt has a significant impact on subsequent processing and the final microstructure and properties of the product.

[0003] The number of eutectic silicon in aluminum-silicon alloys increases with the addition of silicon. When the eutectic silicon structure is not modified, it is in the form of coarse lamellar or needle-like structures. However, when the silicon content exceeds the eutectic composition, primary silicon is formed, which is generally in the form of coarse polygonal blocks. This affects the mechanical properties of the alloy, increases its brittleness, reduces its plasticity and machinability, and thus affects its application.

[0004] To address the aforementioned issues, modification treatment is typically performed on silicon-aluminum alloys in actual production. Current research has found that elements such as Na, K, Re, Ba, Sr, P, and Bi all have a modifying effect on eutectic silicon. These elements are usually added to the aluminum alloy melt in the form of pure metals, master alloys, or fluxes. Existing modifiers generally consist of elemental forms, composite master alloys, or compounds containing these elements. Modifiers containing P, Na, and Sr are the most common. P has a significant modifying effect on primary silicon, while Na and Sr have a significant modifying effect on eutectic silicon. However, during the modification treatment of silicon-aluminum alloys, the introduction of large amounts of P leads to a decrease in the alloy's properties, especially its plasticity and toughness. Na is chemically reactive and easily oxidizes and burns during modification treatment, resulting in a short modification time and easy corrosion damage to the crucible. Sr causes the silicon-aluminum alloy melt to readily absorb hydrogen, leading to porosity when degassing is incomplete, affecting the product's density and causing a decline in the alloy's performance.

[0005] Therefore, in order to produce high-performance, high-quality aluminum alloy castings, it is necessary to develop a modifier that has excellent refining effect, long-lasting modification effectiveness, is safe and environmentally friendly, and can be mass-produced. Summary of the Invention

[0006] The purpose of this invention is to provide a simple, low-cost, high-performance, and stable modifier for cast aluminum alloys and its preparation process.

[0007] The objective of this invention can be achieved through the following technical solutions:

[0008] In a first aspect, the present invention provides a casting aluminum alloy modifier, the material composition of which, by weight percentage, is: 5-20% Sb, 5-10% Ti, 1-2% B, 2-5% V, 1-3% La-Ce mixed rare earth, trace amounts of Be and Hf, and the balance being Al.

[0009] Preferably, the composition of the cast aluminum alloy modifier material by weight percentage is: 10% Sb, 5% Ti, 1% B, 3% V, 1% La-Ce mixed rare earth, 0.02% Be, 0.05% Hf, and the balance is Al.

[0010] Secondly, the present invention also provides a process for preparing a modifier for cast aluminum alloys, comprising the following steps:

[0011] S1. Weigh industrial pure aluminum and intermediate alloy raw materials to prepare aluminum alloy according to the material composition and weight percentage of each component of the cast aluminum alloy modifier.

[0012] S2. Check the materials and tools to ensure they are clean and dry. Put the pure aluminum ingot into the crucible and heat it until it is completely melted. Then add the intermediate alloy raw materials in batches and keep it for 25 minutes. Stir continuously during this period to accelerate the melting and diffusion of alloying elements.

[0013] S3. Adjust the temperature of the molten aluminum to 720-730℃, add Al-5Be master alloy and Al-2Hf master alloy, press them under the molten aluminum to melt, and after all the ingredients have melted, keep the temperature of the molten aluminum at 730℃ and stir and remove the slag.

[0014] S4. The melt undergoes two refining processes.

[0015] S5. After testing the composition of the molten aluminum and adjusting it to meet the requirements, keep it at a constant temperature and let it stand.

[0016] S6. Cast the prepared alloy melt into hexagonal or trapezoidal wire rods, and continuously roll them on a multi-stand rolling mill to form Φ9~10mm round wire rods and wind them into coils.

[0017] S7. The prepared cast aluminum alloy modifier was tested and verified.

[0018] Preferably, the intermediate alloy raw materials in step S1 are Al-10Sb intermediate alloy, Al-10Ti intermediate alloy, Al-5B intermediate alloy, Al-5V intermediate alloy, Al-10Sb intermediate alloy, La-Ce mixed rare earth intermediate alloy, Al-5Be intermediate alloy, and Al-2Hf intermediate alloy.

[0019] Preferably, the specific steps of S2 are as follows: the aluminum liquid is heated to 730°C, the surface slag is removed, and then the temperature is raised to 750-760°C, and Al-10Sb master alloy, Al-10Ti master alloy, Al-5B master alloy, Al-5V master alloy, Al-10Sb master alloy, and La-Ce mixed rare earth master alloy are added in batches.

[0020] Preferably, step S4 specifically includes:

[0021] First refining: The temperature of the molten aluminum is maintained at 720-730℃. The molten aluminum is purified by blowing air through a graphite rotary jet. The refining time is 8 minutes. After the refining is completed, let it stand for 2-3 minutes to thoroughly remove the slag.

[0022] Second refining: The temperature of the molten aluminum is maintained at 710-720℃. The molten aluminum is purified by blowing air through a graphite rotary jet. The refining time is 6 minutes. After the refining is completed, the mixture is left to stand for 2-3 minutes to thoroughly remove the slag.

[0023] Furthermore, the gas used in the blowing purification step in S4 is high-purity argon.

[0024] Preferably, the heat preservation temperature in S5 is 700-710℃, and the standing time is 20 minutes.

[0025] Preferably, in S6, the casting temperature is 690-710℃, the initial rolling temperature is 480-530℃, and the final rolling temperature is 250-280℃.

[0026] Preferably, the experimental verification step in S7 is as follows: 1-15% of the casting aluminum alloy modifier material of the present invention, accounting for the total mass of the corresponding aluminum alloy, is added to the AlSi10Mn aluminum melt for die casting production. After 24 hours, samples are taken from the casting body for microstructure analysis and performance testing.

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

[0028] (1) The modifier raw materials and preparation process for cast aluminum alloys provided by the present invention can effectively improve the modification effect of the microstructure and properties of cast aluminum alloys, so that the modification treatment of hypoeutectic cast aluminum-silicon alloys can achieve the best effect. It can simultaneously improve the problems of α-Al morphology and size, coarse eutectic silicon and Fe phase morphology and size in aluminum alloy melt, thereby improving the room temperature mechanical properties of cast aluminum alloys.

[0029] (2) The process for preparing modifiers for cast aluminum alloys provided by the present invention adopts a continuous casting and rolling process, which can greatly reduce material and labor costs in production, realize mass production and high automation, and produce high-quality modifiers for cast aluminum alloys.

[0030] (3) The modifier for casting aluminum alloy prepared by the present invention can be directly added online from the aluminum melt in the trough to the casting aluminum alloy melt to cast into a remelted ingot for use, or it can be directly put into the side furnace or centralized melting furnace of the casting aluminum alloy melt to be treated, so as to further improve the effect of modification treatment and production efficiency.

[0031] (4) The modifier for casting aluminum alloy prepared by the present invention does not contain Na or P elements in the raw materials. It can significantly improve the strength and plasticity of casting aluminum alloy while refining the grains, and avoid the reduction of casting plasticity caused by Na and P modification. It does not contain Sr elements, which reduces the quality problem of melt gas absorption and hydrogen evolution caused by Sr in aluminum alloy, and avoids the poisoning effect caused by the mixing of Sr and B.

[0032] (5) The modifier for cast aluminum alloy prepared by the present invention contains Sb element in the raw material composition, which can inherit long-term modification and will not weaken the modification effect due to remelting; Hf element is added, which combines with Al to generate Al3Hf particles, which is conducive to heterogeneous nucleation, promotes grain refinement effect, and improves the strength and toughness of the alloy; La-Ce mixed rare earth is added, which purifies the quality of aluminum alloy melt and refines dendritic structure, inhibits the generation of coarse lamellar and long needle-like β-AlFeMnSi phase in aluminum alloy, and enhances the strength and plasticity of cast aluminum alloy. Attached Figure Description

[0033] The present invention will be further described with reference to the accompanying drawings, but the embodiments in the drawings do not constitute any limitation on the present invention. For those skilled in the art, other drawings can be obtained based on the following drawings without creative effort.

[0034] Figure 1 This is a schematic diagram of the continuous casting and rolling production process of the present invention;

[0035] Figure 2 These are OM and SEM tissue images from Embodiment 3 of the present invention;

[0036] Figure 3 These are OM and SEM tissue images of Comparative Example 1;

[0037] Figure 4 These are OM and SEM tissue images from Comparative Example 2;

[0038] Figure 5 These are OM and SEM tissue images of Comparative Example 3. Detailed Implementation

[0039] The embodiments of the present invention will be described in detail below. The embodiments described below are implemented based on the technical solution of the present invention, and detailed implementation methods and specific operation processes are given. However, the protection scope of the present invention is not limited to the embodiments described below.

[0040] Example 1

[0041] A casting aluminum alloy modifier, comprising, by weight percentage: 5% Sb, 5% Ti, 1% B, 2% V, 1% La-Ce mixed rare earth elements, trace elements 0.01% Be and 0.01% Hf, with the balance being Al. Its preparation process is carried out according to the following steps:

[0042] S1. According to the material composition and weight percentage of each component of the cast aluminum alloy modifier, weigh industrial pure aluminum, Al-10Sb master alloy, Al-10Ti master alloy, Al-5B master alloy, Al-5V master alloy, Al-10Sb master alloy, La-Ce mixed rare earth master alloy, Al-5Be master alloy and Al-2Hf master alloy raw materials to make aluminum alloy batching.

[0043] S2. Place the pure aluminum ingot into a crucible and heat it until it is completely melted. Then raise the temperature to 730°C, remove the surface slag, and raise the temperature to 750-760°C. Add Al-10Sb master alloy, Al-10Ti master alloy, Al-5B master alloy, Al-5V master alloy, Al-10Sb master alloy, and La-Ce mixed rare earth master alloy in batches. Keep it for 25 minutes, and stir continuously during the process to accelerate the melting and diffusion of alloying elements.

[0044] S3. Adjust the temperature of the molten aluminum to 720-730℃, add Al-5Be master alloy and Al-2Hf master alloy, press them under the molten aluminum to melt, and after all the ingredients have melted, keep the temperature of the molten aluminum at 730℃ and stir and remove the slag.

[0045] S4. The melt undergoes two refining processes:

[0046] First refining: The aluminum liquid is kept at 720-730℃. The aluminum liquid is purified by blowing air with a graphite rotary jet. High-purity argon is used for refining. The refining time is 8 minutes. After refining, let it stand for 2-3 minutes to thoroughly remove the slag.

[0047] Second refining: The aluminum liquid is kept at 710-720℃. The aluminum liquid is purified by graphite rotary blowing. High-purity argon is used for refining. The refining time is 6 minutes. After refining, let it stand for 2-3 minutes to thoroughly remove slag.

[0048] S5. After testing the composition of the molten aluminum and adjusting it to meet the requirements, set the molten aluminum to 700-710℃ and keep it standing for 20 minutes.

[0049] S6. Cast the prepared alloy melt into hexagonal or trapezoidal wire rods at 690-710℃, and continuously roll them on a multi-stand rolling mill with an entry rolling temperature of 480-530℃ and a final rolling temperature of 250-280℃ to form Φ9~10mm round wire rods and wind them into coils.

[0050] S7. Test and verify the prepared casting aluminum alloy modifier: Add 5% of the casting aluminum alloy modifier material, which accounts for 5% of the total mass of the corresponding aluminum alloy, into AlSi10Mn aluminum melt, and carry out die casting production. After 24 hours, take samples from the casting body for microstructure analysis and performance testing.

[0051] Example 2

[0052] A casting aluminum alloy modifier, the material composition by weight percentage is: 10% Sb, 10% Ti, 2% B, 5% V, 3% La-Ce mixed rare earth, trace elements 0.02% Be and 0.05% Hf, with the balance being Al. The preparation process is the same as in Example 1.

[0053] Example 3

[0054] A casting aluminum alloy modifier, the material composition by weight percentage is: 10% Sb, 5% Ti, 1% B, 3% V, 1% La-Ce mixed rare earth, trace elements 0.01% Be and 0.02% Hf, with the balance being Al. The preparation process is the same as in Example 1.

[0055] Example 4

[0056] A casting aluminum alloy modifier, whose material composition and preparation process steps S1-S6 are the same as those in Example 3, except that in S7, 1% of the casting aluminum alloy modifier material accounting for the total mass of the corresponding aluminum alloy is added to the AlSi10Mn aluminum melt for die casting production. After 24 hours, samples are taken from the casting body for microstructure analysis and performance testing.

[0057] Example 5

[0058] A casting aluminum alloy modifier, whose material composition and preparation process steps S1-S6 are the same as those in Example 3, except that in S7, 10% of the casting aluminum alloy modifier material accounting for the total mass of the corresponding aluminum alloy is added to the AlSi10Mn aluminum melt for die casting production. After 24 hours, samples are taken from the casting body for microstructure analysis and performance testing.

[0059] Example 6

[0060] A casting aluminum alloy modifier, whose material composition and preparation process steps S1-S6 are the same as those in Example 3, except that in S7, 15% of the casting aluminum alloy modifier material accounting for the total mass of the corresponding aluminum alloy is added to the AlSi10Mn aluminum melt for die casting production. After 24 hours, samples are taken from the casting body for microstructure analysis and performance testing.

[0061] Comparative Example 1

[0062] Add 5% of the total mass of the corresponding aluminum alloy, Ai-5Ti-B alloy material, to the AlSi10Mn aluminum melt for die casting. After 24 hours, samples are taken from the casting body for microstructure analysis and performance testing.

[0063] Comparative Example 2

[0064] Add 5% of the total mass of the corresponding aluminum alloy, Ai-10Sr alloy material, to the AlSi10Mn aluminum melt for die casting. After 24 hours, samples are taken from the casting body for microstructure analysis and performance testing.

[0065] Comparative Example 3

[0066] No modifiers or refiners were added to the AlSi10Mn aluminum melt, and die-casting products were produced directly. After 24 hours, samples were taken from the casting body for microstructure analysis and performance testing.

[0067] The AlSi10Mn die-cast aluminum alloys obtained in Examples 1-6 and Comparative Examples 1-3 were subjected to modification treatment, and the mechanical property test results are shown in Table 1.

[0068] Table 1

[0069]

[0070] As can be seen from the mechanical property test results in Table 1, compared with the comparative examples of AlSi10Mn die-cast aluminum alloy without any modifiers and with Ai-5Ti-B and Ai-10Sr, the addition of casting aluminum alloy modifiers to the AlSi10Mn die-cast aluminum alloy in the examples significantly improved its as-cast mechanical properties, and the improvement effect was better. The performance improvement became more significant with increasing element content. Example 6 showed a maximum tensile strength of 290 MPa, a maximum yield strength of 145 MPa, and a maximum elongation of 10.5%.

[0071] The AlSi10Mn die-cast aluminum alloys obtained in Examples 1-6 and Comparative Examples 1-3 were subjected to modification treatment, and the microstructure analysis results are shown in Table 2.

[0072] Table 2

[0073]

[0074] Based on the tissue analysis results in Table 2 and the appendix Figure 2-5 It can be seen that, compared with the comparative example of no modifier and the addition of Ai-5Ti-B and Ai-10Sr, the matrix structure of the embodiment has more uniform and finer α-Al size, eutectic Si is granular, and Fe phase is spherical. The refining effect is more obvious with the increase of the amount added.

[0075] The preferred embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.

Claims

1. A modifier for cast aluminum alloys, characterized in that, Its material composition by weight percentage is: 10% Sb, 5% Ti, 1% B, 3% V, 1% La-Ce mixed rare earth, and trace elements 0.01% Be and 0.02% Hf, with the balance being Al.

2. The process for preparing a casting aluminum alloy modifier according to claim 1, characterized in that, Follow these steps: S1. Weigh industrial pure aluminum and intermediate alloy raw materials to prepare aluminum alloy according to the material composition and weight percentage of each component of the cast aluminum alloy modifier. S2. Check the materials and tools to ensure they are clean and dry. Put the pure aluminum ingot into the crucible and heat it until it is completely melted. Then add the intermediate alloy raw materials in batches and keep it for 25 minutes. Stir continuously during this period to accelerate the melting and diffusion of alloying elements. S3. Adjust the temperature of the molten aluminum to 720~730℃, add Al-5Be master alloy and Al-2Hf master alloy, press them under the molten aluminum to melt, and after all the ingredients have melted, keep the temperature of the molten aluminum at 730℃ and stir and remove the slag. S4. The melt undergoes two refining processes. S5. After testing the composition of the molten aluminum and adjusting it to meet the requirements, keep it at a constant temperature and let it stand. S6. Cast the prepared alloy melt into hexagonal or trapezoidal wire rods, and continuously roll them on a multi-stand rolling mill to form round wire rods with a diameter of 9~10mm and wind them into coils. S7. The prepared casting aluminum alloy modifier was tested and verified. The specific steps of S4 are as follows: First refining: The temperature of the molten aluminum is maintained at 720-730℃. The molten aluminum is purified by blowing air through a graphite rotary jet. The refining time is 8 minutes. After the refining is completed, let it stand for 2-3 minutes to thoroughly remove the slag. Second refining: The temperature of the molten aluminum is maintained at 710-720℃. The molten aluminum is purified by rotating graphite jets. The refining time is 6 minutes. After the refining is completed, the molten aluminum is left to stand for 2-3 minutes to thoroughly remove the slag.

3. The process for preparing the casting aluminum alloy modifier according to claim 2, characterized in that, The intermediate alloy raw materials in step S1 are Al-10Sb intermediate alloy, Al-10Ti intermediate alloy, Al-5B intermediate alloy, Al-5V intermediate alloy, La-Ce mixed rare earth intermediate alloy, Al-5Be intermediate alloy, and Al-2Hf intermediate alloy.

4. The process for preparing the casting aluminum alloy modifier according to claim 3, characterized in that, The specific steps of S2 are as follows: the aluminum liquid is heated to 730°C, the surface slag is removed, and then the temperature is raised to 750~760°C. Al-10Sb master alloy, Al-10Ti master alloy, Al-5B master alloy, Al-5V master alloy and La-Ce mixed rare earth master alloy are added in batches.

5. The process for preparing the casting aluminum alloy modifier according to claim 2, characterized in that, The gas used in the gas blowing purification step is high-purity argon.

6. The process for preparing the casting aluminum alloy modifier according to claim 2, characterized in that, The heat preservation temperature in S5 is 700-710℃, and the standing time is 20 minutes.

7. The process for preparing the casting aluminum alloy modifier according to claim 2, characterized in that, The casting temperature in S6 is 690-710℃, the initial rolling temperature is 480-530℃, and the final rolling temperature is 250-280℃.

8. The process for preparing the modifier for cast aluminum alloys according to claim 2, characterized in that, The experimental verification step in S7 is as follows: 1-15% of the casting aluminum alloy modifier material, accounting for the total mass of the corresponding aluminum alloy, is added to the AlSi10Mn aluminum melt for die casting production. After 24 hours, samples are taken from the casting body for microstructure analysis and performance testing.

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