Homogenizing casting method for aluminum alloy super-large-diameter cast ingot

Abstract

The invention belongs to the technical field of alloy material preparation, and particularly relates to a homogenizing casting method for an aluminum alloy super-large-diameter cast ingot. The aluminum alloy super-large-diameter cast ingot homogenizing casting method comprises the following steps that S1, an Al ingot, an Al-Si alloy, an Al-Ti alloy, an Mg ingot, an Al-B alloy, an Al-Sr alloy and rare earth metal are fed and smelted, and a raw material melt is obtained; s2, the raw material melt is sequentially subjected to degassing treatment, filtering treatment and refining treatment, and alloy melt is obtained; and S3, the alloy melt is cast, and the aluminum alloy super-large-diameter cast ingot is obtained. By means of the method, homogenization of the cast ingot can be achieved, so that the good appearance is obtained, and the mechanical property of the material is improved.

Description

Technical Field

[0001] This invention belongs to the field of alloy material preparation technology, specifically relating to a homogenization melting and casting method for ultra-large diameter aluminum alloy ingots. Background Technology

[0002] Aluminum alloys possess advantages such as low density, high specific strength, high specific modulus, and good plasticity, and have long been used in aerospace, rail transportation, weaponry, and surface ships. Large-size, high-quality, high-strength aluminum alloy ingots are key pillar materials in the high-end aluminum alloy material processing and manufacturing field, representing the scientific and technological level of advanced manufacturing. Currently, heavy industries such as aerospace, rail transportation, weaponry, and surface ships are transitioning to a period of high-quality development. To reduce processing steps, extend service life, and lower costs, high-performance, large-scale, lightweight integral components are replacing assembled components, becoming the primary development trend. This has led to an increasingly strong demand for ultra-large diameter, high-quality aluminum alloy ingots.

[0003] Problems such as coarse and uneven grain size and macroscopic segregation in ultra-large diameter high-strength aluminum alloy ingots are formed and remain in the microstructure during the casting and solidification process. This causes inconsistencies in the deformation, recovery, and recrystallization behavior of grains in different regions, increasing the difficulty of processing and creating hidden dangers for crack initiation and fracture, even leading to cracking and scrapping. Therefore, stringent requirements are placed on the specifications and homogeneity of the ingot. As the size of the ingot increases, the problems of temperature and compositional inhomogeneity become more serious, and defects such as coarse and uneven microstructure, feathery grains, cracking, compositional segregation, shrinkage cavities, and non-metallic inclusions are more likely to occur.

[0004] Chinese patent (publication number CN111471878A) discloses a casting process for 4004 aluminum alloy ingots. The process includes: a) melting Al ingots, Al-Si alloy, and Al-Ti alloy in a furnace; heating to a first temperature and adding Mg ingots for further melting; continuing to heat to a second temperature and adding Al-B alloy and Al-Sr alloy for further melting to obtain a raw material solution; b) degassing and filtering the raw material solution online to obtain an alloy melt; c) refining the alloy melt online to obtain a refined melt; and d) casting the refined melt to obtain a 4004 aluminum alloy ingot. However, the aluminum alloy ingots prepared by this technology have slight defects in appearance, and their mechanical properties such as tensile strength and elongation need improvement, making them unsuitable for the production of ultra-large diameter ingots.

[0005] Therefore, there is an urgent need for a homogenization casting method for ultra-large diameter aluminum alloy ingots. By adding specific rare earth metals and working together with grain refiners, the ingots can be homogenized to obtain a good appearance and improve the mechanical properties of the material. Summary of the Invention

[0006] The purpose of this invention is to provide a homogenized melting and casting method for ultra-large diameter aluminum alloy ingots. This invention involves adding Al ingots, Al-Si alloys, Al-Ti alloys, Mg ingots, Al-B alloys, Al-Sr alloys, and rare earth metals to a raw material melt, which is then subjected to degassing and filtration processes. A compound grain refiner is then used for online refinement to obtain an alloy melt. Finally, the alloy melt is cast to obtain an ultra-large diameter aluminum alloy ingot. Through the synergistic effect of the components, the tensile strength and elongation of the ingot are significantly improved, and homogenization is achieved to obtain a good appearance.

[0007] To achieve the above objectives, the present invention provides the following technical solution: This invention provides a method for homogenizing the casting of ultra-large diameter aluminum alloy ingots, comprising the following steps: S1. Al ingots, Al-Si alloys, Al-Ti alloys, Mg ingots, Al-B alloys, Al-Sr alloys, and rare earth metals are added and smelted to obtain raw material melt; S2. The raw material melt is subjected to degassing, filtration and refining processes in sequence to obtain an alloy melt; S3. Cast the alloy melt to obtain an aluminum alloy ultra-large diameter ingot.

[0008] As a preferred embodiment, the feeding and melting step in step S1 is as follows: by weight, 50-60 parts of Al ingot, 40-50 parts of Al-Si20 alloy, and 0.5-0.9 parts of Al-Ti5 alloy are mixed and heated to melt at 715-725°C. Then, the temperature is raised to 740-750°C and 1.5-2.5 parts of Mg ingot are added and melted for 8-12 minutes. Then, the temperature is raised to 800-820°C and 0.4-0.6 parts of Al-B3 alloy, 0.4-0.6 parts of Al-Sr10 alloy, and 1.2-1.4 parts of rare earth metal are added and stirred for 15-20 minutes to obtain the raw material melt.

[0009] As a preferred embodiment, the weight parts of the Al ingots in this invention can be 50 parts, 52 parts, 54 parts, 56 parts, 58 parts, or 60 parts, etc.

[0010] As a preferred embodiment, the Al-Si2O alloy described in this invention can be in the following weight proportions: 40 parts, 42 parts, 44 parts, 46 parts, 48 ​​parts, or 50 parts, etc.

[0011] As a preferred embodiment, the Al-Ti5 alloy described in this invention can be in the following weight proportions: 0.5 parts, 0.6 parts, 0.7 parts, 0.8 parts, or 0.9 parts, etc.

[0012] As a preferred embodiment, the weight parts of the Mg ingots in this invention can be 1.5 parts, 1.7 parts, 1.9 parts, 2.1 parts, 2.3 parts, or 2.5 parts, etc.

[0013] As a preferred embodiment, the Al-B3 alloy described in this invention may be in the form of 0.4 parts, 0.5 parts, or 0.6 parts by weight, etc.

[0014] As a preferred embodiment, the Al-Sr10 alloy described in this invention may be in the form of 0.4 parts, 0.5 parts, or 0.6 parts by weight, etc.

[0015] As a preferred embodiment, the melting point of the rare earth metal is ≤820℃.

[0016] As a preferred embodiment, the rare earth metal is cerium.

[0017] The rare earth metal selected in this invention is cerium, a metal with a low melting point. This ensures that cerium can interact with the aluminum alloy ingot matrix during the casting process at a temperature not exceeding 820°C, ensuring its full dissolution and uniform distribution, which is beneficial to improving the overall performance of the material.

[0018] As a preferred embodiment, the weight percentage of the rare earth metal in this invention may be 1.2 parts, 1.3 parts, or 1.4 parts, etc.

[0019] This invention improves the overall performance of ultra-large diameter aluminum alloy ingots by controlling the appropriate amount of rare earth metal cerium. If too much cerium is used, the amount of cerium will increase dramatically and the distribution will be uneven, which will hinder the feeding channels and increase micro-shrinkage porosity. At the same time, some cerium and its compounds are prone to segregation at the grain boundaries and weaken the grain boundary bonding force. If too little cerium is used, the number of nucleation cores will decrease, and the as-cast structure will still be coarse dendrites, which cannot significantly refine the grains.

[0020] As a preferred embodiment, the degassing conditions in step S2 are: argon atmosphere, gas flow rate of 4-5 m³ / h. 3 / h.

[0021] As a preferred embodiment, the refining process in step S2 involves adding 1.2 to 1.8 parts of grain refiner to refine the melt online.

[0022] As a preferred embodiment, the grain refiner is an Al-Ti3-B1 grain refiner and a titanium aluminum carbide grain refiner.

[0023] The grain refiner of this invention is selected from Al-Ti3-B1 and titanium aluminum carbide. Al-Ti3-B1 is an aluminum-based master alloy containing Ti and B, while titanium aluminum carbide has a layered hexagonal structure and combines the properties of metal and ceramic. By controlling the mass ratio of the two, they have a synergistic refining effect in the melting and casting process of ultra-large diameter aluminum alloy ingots, thereby improving the comprehensive performance of the material.

[0024] As a preferred embodiment, the mass ratio of Al-Ti3-B1 grain refiner to titanium aluminum carbide grain refiner in the grain refiner is (1~2):1.

[0025] This invention improves the overall performance of materials by controlling the appropriate mass ratio of Al-Ti3-B1 and titanium aluminum carbide. If the amount of Al-Ti3-B1 is too large, the dispersion strengthening of TiC in titanium aluminum carbide is insufficient, resulting in poor mechanical properties. If the amount of titanium aluminum carbide is too large, Al-Ti3-B1 cannot provide enough Al3Ti and TiB2 heterogeneous nucleation cores, resulting in poor homogenization effect, easy appearance of cracks, and reduced mechanical properties.

[0026] As a preferred embodiment, the casting temperature in step S3 is 740~760℃.

[0027] As a preferred embodiment, the casting speed is 50~60 mm / min.

[0028] As a preferred embodiment, the cooling water flow rate for casting is 40~50m³. 3 / h.

[0029] As a preferred embodiment, the casting in step S3 is carried out under electromagnetic stirring.

[0030] As a preferred embodiment, the electromagnetic stirring conditions are: frequency of 25~30Hz, current of 440~460A, and commutation time of 6~8s.

[0031] Compared with the prior art, the advantages and beneficial effects of the present invention are as follows: (1) This invention uses Al ingots, Al-Si alloys, Al-Ti alloys, Mg ingots, Al-B alloys, and Al-Sr alloys as the main raw materials, and adds low-melting-point rare earth metal cerium for modification treatment. It is combined with a composite grain refiner composed of Al-Ti3-B1 and titanium aluminum carbide. Through the synergistic effect of each component, the homogenization of aluminum alloy ultra-large diameter ingots is achieved, which improves tensile strength and elongation while ensuring that the appearance of the ingot is free of obvious defects.

[0032] (2) The cerium of the present invention can effectively inhibit grain growth during the solidification process of aluminum alloy, promote the formation of equiaxed crystals and reduce columnar crystal regions, thereby obtaining a more uniform and fine microstructure, which helps to reduce casting defects such as surface cracks, shrinkage porosity and gas pores, and improve the surface finish of the ingot; the dispersed intermetallic compounds formed by cerium can pin dislocations and grain boundaries, hinder plastic deformation and improve the tensile strength of the material; the grain refining effect of cerium makes plastic deformation more uniform, reduces local necking and deformation, thereby improving the overall elongation.

[0033] (3) The grain refiner of the present invention provides a large amount of Al-Ti3-B1. and Heterogeneous nucleation nuclei promote uniform nucleation of α-Al, effectively reducing defects on the material surface; TiB2 of Al-Ti3-B1 and TiC of titanium aluminum carbide are dispersed in the matrix during solidification, hindering dislocation slip and improving tensile strength through dispersion strengthening; Al-Ti3-B1 and titanium aluminum carbide increase nucleation density through multiphase nucleation mechanism, obtaining finer and rounder grains, which is beneficial to the coordination of plastic deformation, thereby obtaining good elongation. Detailed Implementation

[0034] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0035] The sources of some components in the examples and comparative examples are as follows: Al-Si alloy, Al-Si20, purchased from Sichuan Lande High-Tech Industry Co., Ltd.; Al-Ti alloy, Al-Ti5, purchased from Sichuan Lande High-Tech Industry Co., Ltd.; Al-B alloy, Al-B3, purchased from Sichuan Lande High-Tech Industry Co., Ltd.; Al-Sr alloy, Al-Sr10, purchased from Sichuan Lande High-Tech Industry Co., Ltd.; Metallic cerium, CAS No. 7440-45-1, melting point 795°C, purchased from Shanghai Maclean Biochemical Technology Co., Ltd. Lanthanum metal, CAS No. 7439-91-0, melting point 920°C, purchased from Shanghai Maclean Biochemical Technology Co., Ltd. Al-Ti3-B1 refining agent was purchased from Sichuan Lande High-Tech Industry Co., Ltd. Titanium aluminate carbide refining agent, product number T463084, purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0036] Example 1 This embodiment provides a method for homogenizing the casting of ultra-large diameter aluminum alloy ingots, including the following steps: S1. By weight, first mix 55 parts Al ingot, 50 parts Al-Si20 alloy, and 0.5 parts Al-Ti5 alloy and heat to melt at 720℃. Then, raise the temperature to 745℃ and add 1.6 parts Mg ingot to melt for 10 minutes. Then, raise the temperature to 810℃ and add 0.5 parts Al-B3 alloy, 0.5 parts Al-Sr10 alloy, and 1.3 parts metallic cerium and stir for 18 minutes to obtain the raw material melt. S2. The raw material melt is subjected to degassing treatment sequentially (under an argon atmosphere, with a gas flow rate of 4.5 m³ / h). 3 The melt is subjected to online refining treatment by adding 1.8 parts of grain refiner (1.2 parts of Al-Ti3-B1 and 0.6 parts of titanium aluminum carbide) to obtain alloy melt. S3. The alloy melt is cast under electromagnetic stirring (frequency 28Hz, current 450A, reversal time 7s) (temperature 750℃, speed 55mm / min, cooling water flow rate 45m³ / min). 3 / h), to obtain ultra-large diameter aluminum alloy ingots.

[0037] Example 2 This embodiment provides a method for homogenizing the casting of ultra-large diameter aluminum alloy ingots, including the following steps: S1. By weight, first mix 60 parts Al ingot, 55 parts Al-Si20 alloy, and 0.9 parts Al-Ti5 alloy and heat to melt at 725℃. Then, raise the temperature to 750℃, add 2.5 parts Mg ingot and melt for 12 minutes. Then, raise the temperature to 820℃, add 0.6 parts Al-B3 alloy, 0.6 parts Al-Sr10 alloy, and 1.4 parts metallic cerium and stir for 20 minutes to obtain the raw material melt. S2. The raw material melt is subjected to degassing treatment in sequence (under argon atmosphere, gas flow rate is 5m³ / h). 3 The melt is subjected to online refining treatment by filtering and then adding 1.6 parts of grain refiner (1.0 parts of Al-Ti3-B1 and 0.6 parts of titanium aluminum carbide) to obtain alloy melt. S3. The alloy melt is cast under electromagnetic stirring (frequency 30Hz, current 460A, reversal time 8s) (temperature 760℃, speed 60mm / min, cooling water flow rate 50m³ / min). 3 / h), to obtain ultra-large diameter aluminum alloy ingots.

[0038] Example 3 This embodiment provides a method for homogenizing the casting of ultra-large diameter aluminum alloy ingots, including the following steps: S1. By weight, first mix 50 parts Al ingot, 40 parts Al-Si20 alloy, and 0.5 parts Al-Ti5 alloy and heat to melt at 715℃. Then, raise the temperature to 740℃, add 1.5 parts Mg ingot and melt for 8 minutes. Then, raise the temperature to 800℃, add 0.4 parts Al-B3 alloy, 0.4 parts Al-Sr10 alloy, and 1.2 parts metallic cerium and stir for 15 minutes to obtain the raw material melt. S2. The raw material melt is subjected to degassing treatment sequentially (under an argon atmosphere, with a gas flow rate of 4 m³ / h). 3 The melt is processed by filtering and then adding 1.2 parts of grain refiner (0.6 parts Al-Ti3-B1 and 0.6 parts titanium aluminum carbide) to refine the melt online, thus obtaining an alloy melt. S3. The alloy melt is cast under electromagnetic stirring (frequency 25Hz, current 440A, reversal time 6s) (temperature 740℃, speed 50mm / min, cooling water flow rate 40m³ / min). 3 / h), to obtain ultra-large diameter aluminum alloy ingots.

[0039] Comparative Example 1 The difference between this comparative example and Example 1 is that 1.4 parts of rare earth metal cerium are not added during the feeding and smelting process, and Al-Ti3-B1 grain refiner is used entirely in the grain refinement process.

[0040] Comparative Example 2 The difference between this comparative example and Example 1 is that 1.4 parts of rare earth metal cerium are not added during the feeding and smelting process.

[0041] Comparative Example 3 The difference between this comparative example and Example 1 is that lanthanum metal was used instead of cerium metal in the charging smelting process.

[0042] Comparative Example 4 The difference between this comparative example and Example 1 is that the amount of metallic cerium used in the charging and smelting process is changed to 0.4 parts.

[0043] Comparative Example 5 The difference between this comparative example and Example 1 is that the amount of metallic cerium used in the charging and smelting process is changed to 2.8 parts.

[0044] Comparative Example 6 The difference between this comparative example and Example 1 is that the amount of Al-Ti3-B1 in the grain refiner is changed to 1.6 parts, and the amount of titanium aluminum carbide is changed to 0.2 parts.

[0045] Comparative Example 7 The difference between this comparative example and Example 1 is that the amount of Al-Ti3-B1 in the grain refiner is changed to 0.2 parts, and the amount of titanium aluminum carbide is changed to 1.6 parts.

[0046] Performance testing Mechanical property testing: The tests shall be conducted in accordance with the requirements of GB / T 16865-2023 Tensile test specimens and methods for wrought aluminum, magnesium and their alloy processed products.

[0047] Table 1 Performance Test Results The performance test results above show that Examples 1-3 have the best overall effect. This is mainly because they use Al ingots, Al-Si alloys, Al-Ti alloys, Mg ingots, Al-B alloys, and Al-Sr alloys as the main raw materials, and add low-melting-point rare earth metal cerium for modification treatment. Combined with a composite grain refiner composed of Al-Ti3-B1 and titanium aluminum carbide, the homogenization of ultra-large diameter aluminum alloy ingots is achieved through the synergistic effect of each component. While ensuring that there are no obvious defects in the appearance of the ingot, the tensile strength and elongation are improved.

[0048] Compared to Example 1, Comparative Example 1 did not add 1.4 parts of rare earth cerium metal during the feeding and melting process, and the grain refiner used in the refining treatment was entirely Al-Ti3-B1 grain refiner. The lack of cerium metal and titanium aluminum carbide resulted in poor appearance and decreased mechanical properties. Compared to Example 1, Comparative Example 2 did not add 1.4 parts of rare earth cerium metal during the feeding and melting process, resulting in poor appearance and decreased mechanical properties. Compared to Example 1, Comparative Example 3 used lanthanum metal instead of cerium metal during the feeding and melting process. The higher melting point of lanthanum metal led to poor results, resulting in poor appearance and decreased mechanical properties. Compared to Example 1, the amount of cerium metal used in Comparative Example 4 was changed to 0.4 parts during the feeding and melting process. The insufficient amount of cerium metal resulted in poor performance. If the grain refiner is not properly prepared, the appearance will be poor and the mechanical properties will decrease. Compared with Example 1, the amount of metallic cerium in the smelting process of Comparative Example 5 was changed to 2.8 parts. Due to the excessive amount of metallic cerium, the effect was poor, resulting in a poor appearance and decreased mechanical properties. Compared with Example 1, the amount of Al-Ti3-B1 in the grain refiner of Comparative Example 6 was changed to 1.6 parts and the amount of titanium aluminum carbide was changed to 0.2 parts. Due to the insufficient amount of titanium aluminum carbide, the compounding effect was poor, resulting in a poor appearance and decreased mechanical properties. Compared with Example 1, the amount of Al-Ti3-B1 in the grain refiner of Comparative Example 7 was changed to 0.2 parts and the amount of titanium aluminum carbide was changed to 1.6 parts. Due to the excessive amount of titanium aluminum carbide, the compounding effect was poor, resulting in a poor appearance and decreased mechanical properties.

Claims

1. A method for homogenizing and casting ultra-large diameter aluminum alloy ingots, characterized in that, Includes the following steps: S1. Al ingots, Al-Si alloys, Al-Ti alloys, Mg ingots, Al-B alloys, Al-Sr alloys, and rare earth metals are added and smelted to obtain raw material melt; S2. The raw material melt is subjected to degassing, filtration and refining processes in sequence to obtain an alloy melt; S3. Cast the alloy melt to obtain an aluminum alloy ultra-large diameter ingot.

2. The method for homogenizing and casting ultra-large diameter aluminum alloy ingots according to claim 1, characterized in that, The charging and melting steps described in step S1 are as follows: by weight, 50-60 parts of Al ingot, 40-50 parts of Al-Si20 alloy, and 0.5-0.9 parts of Al-Ti5 alloy are mixed and heated to melt at 715-725℃. Then, the temperature is raised to 740-750℃ and 1.5-2.5 parts of Mg ingot are added and melted for 8-12 minutes. Then, the temperature is raised to 800-820℃ and 0.4-0.6 parts of Al-B3 alloy, 0.4-0.6 parts of Al-Sr10 alloy, and 1.2-1.4 parts of rare earth metal are added and stirred for 15-20 minutes to obtain the raw material melt.

3. The method for homogenizing and casting ultra-large diameter aluminum alloy ingots according to claim 2, characterized in that, The melting point of the rare earth metal is ≤820℃.

4. The method for homogenizing and casting ultra-large diameter aluminum alloy ingots according to claim 2, characterized in that, The rare earth metal is cerium.

5. The method for homogenizing and casting ultra-large diameter aluminum alloy ingots according to claim 1, characterized in that, The degassing conditions described in step S2 are: argon atmosphere, gas flow rate of 4-5 m³ / h. 3 / h.

6. The method for homogenizing and casting ultra-large diameter aluminum alloy ingots according to claim 1, characterized in that, The refining process described in step S2 involves adding 1.2 to 1.8 parts of grain refiner to refine the melt online.

7. The method for homogenizing and casting ultra-large diameter aluminum alloy ingots according to claim 6, characterized in that, The grain refiner is an Al-Ti3-B1 grain refiner and a titanium aluminum carbide grain refiner.

8. The method for homogenizing and casting ultra-large diameter aluminum alloy ingots according to claim 6, characterized in that, The mass ratio of Al-Ti3-B1 grain refiner to titanium aluminum carbide grain refiner in the grain refiner is (1~2):

1.

9. The method for homogenizing and casting ultra-large diameter aluminum alloy ingots according to claim 1, characterized in that, The casting temperature in step S3 is 740~760℃; The casting speed is 50~60 mm / min; The cooling water flow rate for casting is 40-50 m³ / h. 3 / h.

10. The method for homogenizing and casting ultra-large diameter aluminum alloy ingots according to claim 1, characterized in that, The casting described in step S3 is carried out under electromagnetic stirring; The conditions for electromagnetic stirring are: frequency of 25~30Hz, current of 440~460A, and commutation time of 6~8s.

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