Cast aluminum alloy alterant and preparation process

Abstract

The invention provides a cast aluminum alloy alterant and a preparation process thereof. The cast aluminum alloy alterant comprises Sb, Ti, B, V, La-Ce mixed rare earth and microelements Be and Hf. The preparation process comprises the steps of smelting, refining, continuous rolling and experimental verification. According to the alterant raw materials for the cast aluminum alloy and the preparation technology, the aluminum alloy quality problem caused by the fact that Na, P and Sr elements are added into an aluminum alloy alterant is avoided, the modification effect of the structure and performance of the cast aluminum alloy is effectively improved, and the room-temperature mechanical performance of the cast aluminum alloy is improved; the production cost is reduced, the production efficiency and the product quality are improved, and batch production and high automation are achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of cast aluminum alloys, and in particular to a cast aluminum alloy modifier and a preparation process thereof. Background Art

[0002] Cast aluminum alloys, with their excellent casting properties, are the most widely used aluminum alloy material in automobiles. Aluminum-silicon alloys are the most widely 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 manufacturing process. The quality of the alloy melt has a significant impact on subsequent processing and the final product structure and performance.

[0003] The amount of eutectics in aluminum-silicon alloys will increase with the increase of silicon addition. The eutectic silicon structure is in the form of coarse laths or needles without metamorphism. When the silicon content exceeds the eutectic composition, primary silicon will be formed, which is generally in the form of coarse polygonal blocks, affecting the mechanical properties of the alloy, increasing the brittleness of the alloy, reducing the plasticity and cutting performance of the alloy, and thus affecting its application.

[0004] To address these issues, silicon-aluminum alloys are typically subjected to a modification treatment 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 typically added to the aluminum alloy melt in the form of pure metals, master alloys, and fluxes. Existing modifiers typically consist of simple elements, 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 significant modifying effects on eutectic silicon. However, during the modification of silicon-aluminum alloys, the introduction of large amounts of P can lead to a decrease in the alloy's properties, particularly its plasticity and toughness. Na, due to its active chemical properties, is easily oxidized and burned during the modification process, resulting in a short modification time and the tendency to corrode and damage the crucible. Sr can easily absorb hydrogen into the silicon-aluminum alloy melt, creating pores when degassing is incomplete, affecting the product's density and leading to a decrease 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-term effectiveness, is safe and environmentally friendly, and can be produced on a large scale. Summary of the Invention

[0006] The purpose of the present invention is to provide a casting aluminum alloy modifier and a preparation process thereof with simple process, low cost, excellent performance and stability.

[0007] The purpose of the present invention can be achieved by the following technical solutions:

[0008] In a first aspect, the present invention provides a casting aluminum alloy modifier, the material components of which are calculated by weight percentage: 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 is Al.

[0009] Preferably, the cast aluminum alloy modifier material composition is calculated by weight as follows: 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] In a second aspect, the present invention further provides a process for preparing a cast aluminum alloy modifier, which is carried out according to the following steps:

[0011] S1. Weighing industrial pure aluminum and master alloy raw materials to prepare aluminum alloy ingredients according to the material components and weight percentages of the casting aluminum alloy modifier;

[0012] S2. Check the materials and tools to ensure they are clean and dry. Place the pure aluminum ingot into the crucible and heat it until it is completely melted. Then increase the temperature and add the intermediate alloy raw materials in batches. Keep stirring for 25 minutes to accelerate the dissolution and diffusion of the alloy elements.

[0013] S3. Adjust the aluminum liquid temperature to 720-730℃, add Al-5Be master alloy and Al-2Hf master alloy, press them into the bottom of the aluminum liquid to melt, and after all the ingredients are melted, maintain the aluminum liquid temperature at 730℃ and stir to skim off the slag;

[0014] S4, refining the melt twice;

[0015] S5. Check the composition of the aluminum liquid and adjust it to meet the requirements, then keep it warm and let it stand;

[0016] S6. Casting the prepared alloy melt into a hexagonal or trapezoidal wire billet, continuously rolling it on a rolling mill with multiple stands to form a round wire rod with a diameter of 9 to 10 mm and winding it into a coil;

[0017] S7. Conduct test verification on the prepared casting aluminum alloy modifier.

[0018] Preferably, the master alloy raw materials in step S1 are 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.

[0019] Preferably, the specific steps of S2 are: heating the aluminum liquid to 730°C, scraping off the surface slag, then heating it to 750-760°C, and adding 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.

[0020] Preferably, the specific steps of S4 are:

[0021] First refining: The aluminum liquid temperature is maintained at 720-730℃, and graphite rotary jet blowing is used to purify the aluminum liquid. The refining time is 8 minutes. After the refining is completed, it is left to stand for 2-3 minutes and the slag is completely removed;

[0022] Second refining: The aluminum liquid temperature is maintained at 710-720℃, and graphite rotary jet blowing is used to purify the aluminum liquid. The refining time is 6 minutes. After the end, it is left to stand for 2-3 minutes and the slag is completely removed.

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

[0024] Preferably, the holding temperature in S5 is 700-710° C., and the standing time is 20 min.

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

[0026] Preferably, the test verification step in S7 is: adding the casting aluminum alloy modifier material of the present invention accounting for 1 to 15% of the total mass of the corresponding aluminum alloy to the AlSi10Mn aluminum melt to produce die-cast products, and taking samples from the casting body after 24 hours for microstructure analysis and performance testing.

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

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

[0029] (2) The preparation process of the modifier for cast aluminum alloy provided by the present invention adopts a continuous casting and rolling process, which can greatly reduce the material and labor costs in production, realize batch production and high automation, and at the same time produce high-quality modifier for cast aluminum alloy.

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

[0031] (4) The modifier for cast aluminum alloy prepared by the present invention does not contain Na and P elements in the raw materials, which can significantly improve the strength and plasticity of the cast aluminum alloy while refining the grains, avoiding the reduction of the plasticity of the casting due to the modification of Na and P; does not contain Sr elements, reducing the quality problem of melt absorption and hydrogen evolution caused by Sr in the aluminum alloy, and at the same time avoiding the poisoning effect caused by the mixture of Sr and B.

[0032] (5) The modifier for cast aluminum alloy prepared by the present invention has Sb element added to the raw material composition, which can achieve long-term modification and will not weaken the modification effect due to remelting; Hf element is added to combine with Al to form Al3Hf particles, which is beneficial to the formation of heterogeneous nucleation, promotes grain refinement, and improves the strength and toughness of the alloy; La-Ce mixed rare earth is added to purify the quality of the aluminum alloy melt and refine the dendrite structure, inhibit the generation of coarse lamellar and long needle-shaped β-AlFeMnSi phases in the aluminum alloy, and enhance the strength and plasticity of the cast aluminum alloy. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The present invention is further described with reference to the accompanying drawings. However, the embodiments in the accompanying drawings do not constitute any limitation to the present invention. A person skilled in the art can obtain other drawings based on the following drawings without inventive effort.

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

[0035] Figure 2 OM and SEM images of Example 3 of the present invention;

[0036] Figure 3 OM and SEM images of comparative example 1;

[0037] Figure 4 OM and SEM images of comparative example 2;

[0038] Figure 5 These are the OM and SEM organization pictures of Comparative Example 3. DETAILED DESCRIPTION

[0039] The embodiments of the present invention are described in detail below. The following embodiments are implemented based on the technical solutions of the present invention, and provide detailed implementation methods and specific operating procedures. However, the protection scope of the present invention is not limited to the following embodiments.

[0040] Example 1

[0041] A cast aluminum alloy modifier comprises, by weight, 5% Sb, 5% Ti, 1% B, 2% V, 1% La-Ce mixed rare earth, 0.01% Be and 0.01% Hf as trace elements, with the balance being Al. The preparation process is as follows:

[0042] S1. According to the material components and weight percentages of the cast aluminum alloy modifier, 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 are weighed to prepare aluminum alloy ingredients;

[0043] S2. Place a pure aluminum ingot into a crucible and heat it until it is completely melted. Then raise the temperature to 730°C, scrape off the scum on the surface, and then 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 stirring for 25 minutes to accelerate the dissolution and diffusion of the alloying elements.

[0044] S3. Adjust the aluminum liquid temperature to 720-730℃, add Al-5Be master alloy and Al-2Hf master alloy, press them into the bottom of the aluminum liquid to melt, and after all the ingredients are melted, maintain the aluminum liquid temperature at 730℃ and stir to skim off the slag;

[0045] S4, refining the melt twice:

[0046] First refining: The aluminum liquid is maintained at 720-730℃, and graphite rotary jet blowing is used to purify the aluminum liquid. High-purity argon is used as the refining gas. The refining time is 8 minutes. After the refining is completed, it is allowed to stand for 2-3 minutes and the slag is completely removed.

[0047] Second refining: The aluminum liquid is maintained at 710-720℃, and graphite rotary jet blowing is used to purify the aluminum liquid. High-purity argon is used as the refining gas. The refining time is 6 minutes. After the refining is completed, it is allowed to stand for 2-3 minutes and the slag is completely removed.

[0048] S5. After testing the aluminum liquid composition and adjusting it to meet the requirements, the aluminum liquid is kept at 700-710℃ and allowed to stand for 20 minutes.

[0049] S6. Casting the prepared alloy melt into a hexagonal or trapezoidal wire billet at 690-710° C., performing continuous rolling on a rolling mill with multiple stands, with a feed temperature of 480-530° C. and a finishing temperature of 250-280° C., into a Φ9-10 mm round wire rod and winding it into a coil;

[0050] S7. Test and verify the prepared casting aluminum alloy modifier: add the casting aluminum alloy modifier material accounting for 5% of the total mass of the corresponding aluminum alloy to the AlSi10Mn aluminum melt to produce die-cast products. After 24 hours, samples are taken from the casting body for microstructure analysis and performance testing.

[0051] Example 2

[0052] A cast aluminum alloy modifier comprises the following components by weight: 10% Sb, 10% Ti, 2% B, 5% V, 3% La-Ce mixed rare earth, 0.02% Be and 0.05% Hf as trace elements, and the balance being Al. The preparation process is the same as that of Example 1.

[0053] Example 3

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

[0055] Example 4

[0056] A casting aluminum alloy modifier, whose material composition and preparation process S1-S6 steps are the same as those in Example 3, except that in S7, a casting aluminum alloy modifier material accounting for 1% of the total mass of the corresponding aluminum alloy is added to an AlSi10Mn aluminum melt to produce a die-cast product. 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 S1-S6 steps are the same as those in Example 3, except that in S7, a casting aluminum alloy modifier material accounting for 10% of the total mass of the corresponding aluminum alloy is added to an AlSi10Mn aluminum melt to produce a die-cast product. 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 S1-S6 steps are the same as those in Example 3, except that in S7, a casting aluminum alloy modifier material accounting for 15% of the total mass of the corresponding aluminum alloy is added to an AlSi10Mn aluminum melt to produce a die-cast product. After 24 hours, samples are taken from the casting body for microstructure analysis and performance testing.

[0061] Comparative Example 1

[0062] Ai-5Ti-B alloy material accounting for 5% of the total mass of the corresponding aluminum alloy was added to the AlSi10Mn aluminum melt to produce die-cast products. Samples were taken from the casting body after 24 hours for microstructure analysis and performance testing.

[0063] Comparative Example 2

[0064] Ai-10Sr alloy material accounting for 5% of the total mass of the corresponding aluminum alloy was added to the AlSi10Mn aluminum melt to produce die-cast products. Samples were taken from the casting body after 24 hours for microstructure analysis and performance testing.

[0065] Comparative Example 3

[0066] No modifier or refiner is added to the AlSi10Mn aluminum melt, and die-cast products are directly produced. Samples are taken from the casting body after 24 hours for microstructure analysis and performance testing.

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

[0068] Table 1

[0069]

[0070] The mechanical property test results in Table 1 show that, compared to the comparative examples without any modifiers and with the addition of Ai-5Ti-B and Ai-10Sr, the addition of the casting aluminum alloy modifier material to the AlSi10Mn die-cast aluminum alloy in Example 6 significantly improves its as-cast mechanical properties, with good improvement. The performance improvement becomes more significant with increasing element content. Example 6 achieves 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 prepared in Examples 1 to 6 and Comparative Examples 1 to 3 were subjected to modification treatment, and the microstructure analysis results are shown in Table 2.

[0072] Table 2

[0073]

[0074] According to the organizational analysis results in Table 2 and the attached Figure 2-5 It can be seen that compared with the comparative examples without adding any modifier and adding Ai-5Ti-B and Ai-10Sr, the α-Al size in the matrix structure of the embodiment is more uniform and fine, the eutectic Si is granular, and the Fe phase is spherical. As the addition amount increases, the refinement effect is more obvious.

[0075] The above describes in detail the preferred embodiments of the present invention. It should be understood that numerous modifications and variations based on the concepts of the present invention can be made by those skilled in the art without inventive effort. Therefore, any technical solution that can be derived by those skilled in the art based on the concepts of the present invention through logical analysis, reasoning, or limited experimentation based on the existing technology should be within the scope of protection defined by the claims.

Claims

1. A cast aluminum alloy modifier, characterized in that: The material components thereof are calculated by weight percentage as follows: 5-20% Sb, 5-10% Ti, 1-2% B, 2-5% V, 1-3% La-Ce mixed rare earth, and trace elements 0.01-0.02% Be and 0.01-0.05% Hf, and the balance is Al.

2. The cast aluminum alloy modifier according to claim 1, characterized in that: The casting aluminum alloy modifier material components are calculated by weight percentage: 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.

3. The process for preparing a casting aluminum alloy modifier according to claim 1, characterized in that: Follow these steps: S1. According to the material components of the cast aluminum alloy modifier and the weight percentage of each component, industrial pure aluminum and master alloy raw materials are weighed to prepare aluminum alloy ingredients; 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 increase the temperature and add the intermediate alloy raw materials in batches. Keep stirring for 25 minutes to accelerate the melting and diffusion of the alloy elements. S3. Adjust the aluminum liquid temperature to 720-730°C, add Al-5Be master alloy and Al-2Hf master alloy, press them under the aluminum liquid to melt, and after all the ingredients are melted, keep the aluminum liquid temperature at 730°C and stir to remove slag; S4, refining the melt twice; S5. Check the aluminum liquid composition and adjust it to the qualified level, then keep it warm and let it stand; S6, casting the prepared alloy melt into a hexagonal or trapezoidal wire billet, and continuously rolling it on a rolling mill on multiple sets of stands to roll it into a round wire rod of Φ9-10 mm and wind it into a coil; S7. Conduct test verification on the prepared casting aluminum alloy modifier.

4. The process for preparing a casting aluminum alloy modifier according to claim 3, characterized in that: The master alloy raw materials in step S1 are 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.

5. The process for preparing a casting aluminum alloy modifier according to claim 3, characterized in that: The specific steps of S2 are: heating the aluminum liquid to 730° C., scraping off the surface scum, then heating it to 750-760° C., and adding 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.

6. The process for preparing a casting aluminum alloy modifier according to claim 3, characterized in that: The specific steps of S4 are: First refining: The aluminum liquid temperature is maintained at 720-730℃, and graphite rotary jet is used to purify the aluminum liquid. The refining time is 8 minutes. After the refining is completed, it is left to stand for 2-3 minutes and the slag is completely removed; Second refining: The aluminum liquid temperature is maintained at 710-720℃, and graphite rotary jet blowing is used to purify the aluminum liquid. The refining time is 6 minutes. After the refining is completed, it is left to stand for 2-3 minutes and the slag is completely removed.

7. The process for preparing a casting aluminum alloy modifier according to claim 6, characterized in that: The gas used in the purge step is high-purity argon.

8. The process for preparing a casting aluminum alloy modifier according to claim 3, characterized in that: The insulation temperature in S5 is 700-710° C., and the standing time is 20 minutes.

9. The process for preparing a casting aluminum alloy modifier according to claim 3, characterized in that: In the S6, the casting temperature is 690-710°C, the rolling temperature is 480-530°C, and the final rolling temperature is 250-280°C.

10. The process for preparing a casting aluminum alloy modifier according to claim 3, characterized in that: The test verification steps in S7 are: adding the casting aluminum alloy modifier material of the present invention accounting for 1 to 15% of the total mass of the corresponding aluminum alloy to the AlSi10Mn aluminum melt to produce die-cast products, and taking samples from the casting body after 24 hours for tissue analysis and performance testing.

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