Aluminum alloy cast ingot blank for ship and maritime work and production method

Abstract

The invention discloses an aluminum alloy cast ingot blank for ship maritime work and a production method. The aluminum alloy cast ingot blank comprises the following chemical components in percentage by mass: 0.7-4.8% of Mg, 1.0-1.1% of Si, 0.2-0.8% of Mn, 0.07-0.2% of Zr, 0.10-0.20% of Er, 0.03-0.05% of Ti, 0.06-0.12% of Cu, less than or equal to 0.16% of Fe, less than or equal to 0.05% of Zn and the balance of Al. By optimizing and matching the aluminum alloy ingot casting process, the problem that structure defects and metallurgical defects are prone to occurring in the production process of an existing aluminum alloy ingot casting blank for ship and maritime work is solved. The aluminum alloy cast ingot blank for ship and maritime work is good in appearance quality and excellent in surface and internal quality, the casting qualification rate of the large-size cast ingot blank is increased to 100%, the product strength performance is improved by 20-30 MPa, and the hydrogen content of melt is smaller than or equal to 0.11 ml / 100 gAl.

Description

Technical Field

[0001] This application belongs to the field of aluminum alloy technology, specifically relating to an aluminum alloy ingot for marine engineering and its production method. Background Technology

[0002] With the comprehensive development of the shipbuilding industry and the steady progress towards the carbon peak and carbon neutrality goals, the lightweighting of ships is receiving increasing attention. Aluminum alloys have low density, are lightweight, have good cold and hot forming properties, and excellent corrosion resistance. Therefore, using aluminum alloys to replace steel in the manufacture of ships and marine engineering equipment can significantly reduce ship weight, improve ship maneuverability and carrying capacity, reduce maintenance costs, and extend the service life of marine engineering equipment. As a result, aluminum alloys have wide applications in shipbuilding and marine engineering equipment manufacturing.

[0003] Aluminum alloy tubes, bars, and profiles used in the manufacture of ships and other marine engineering equipment are produced by extruding aluminum alloy round ingots. Marine and marine engineering aluminum alloy round ingots are mainly produced through processes such as batching, smelting, refining, casting, and homogenization, primarily using high-magnesium, high-silicon grades such as 5xxx and 6xxx. However, the production process of high-magnesium, high-silicon aluminum alloy ingots often results in metallurgical defects such as central cracks, coarse grains, and surface inclusions due to the high silicon and magnesium content. Furthermore, to further improve the overall performance of marine and marine engineering aluminum alloys, rare earth elements need to be added for tempering, and melt purification treatments such as alkali metal removal are required, making the smelting, refining, casting, and homogenization control of high-magnesium, high-silicon aluminum alloy ingots even more challenging. Summary of the Invention

[0004] In view of this, this application provides an aluminum alloy ingot for marine engineering and its production method. The main purpose is to solve the production and quality control problems of aluminum alloy ingots for marine engineering, which requires optimization and matching of a series of processes such as aluminum alloy ingot batching, smelting, refining, melt treatment, casting, and homogenization.

[0005] To achieve the above objectives, the present application provides an aluminum alloy ingot for marine engineering, the chemical composition of which, by mass percentage, is: 0.7-4.8%Mg, 1.0-1.1%Si, 0.2-0.8%Mn, 0.07-0.2%Zr, 0.10-0.20%Er, 0.03-0.05%Ti, 0.06-0.12%Cu, Fe≤0.16%, Zn≤0.05%, with the balance being Al.

[0006] This application also provides a method for producing the above-mentioned aluminum alloy ingot for marine engineering, the steps of which are as follows: (1) Material addition: According to the planned aluminum input, a certain amount of aluminum-manganese master alloy, rare earth master alloy, metallic magnesium and recycled material are added to the aluminum alloy smelting furnace in advance; then the high-temperature aluminum liquid produced by aluminum electrolysis is transferred to the aluminum alloy smelting furnace using a vacuum aluminum ladle. (2) Melting and refining: During the process of transferring the high-temperature aluminum liquid to the aluminum alloy melting furnace, the aluminum alloy melt is electromagnetically stirred at the same time; then, the aluminum alloy melt is melted at 780-790℃ for 20-30 minutes; the composition is adjusted according to the requirements, and high-purity argon and refining agent are introduced for refining for 10-15 minutes. (3) Semi-continuous casting: Under the condition of a temperature of 740-750℃, the aluminum alloy melt with qualified composition obtained in step (2) above is introduced into a settling furnace, and the high-purity argon gas and the refining agent are introduced for refining for 10-15 minutes, and then settling for 20-30 minutes; then Al-Ti wire is added under the conditions of casting speed of 50-80mm / min, casting temperature of 710-730℃, and casting cooling water pressure of 0.03-0.10MPa, and semi-continuous casting is carried out under the condition of casting speed of 400-600mm / min. The casting process is independently supplied with oil and gas to obtain aluminum alloy ingot billet; (4) Homogenization treatment: The aluminum alloy ingot billet that has passed the appearance inspection is loaded into a hot air circulating homogenization furnace for homogenization treatment.

[0007] In some embodiments, the manganese content of the aluminum-manganese master alloy is 1.2-1.6%; the rare earth content of the rare earth master alloy is 5-10%, and the rare earth elements include Ce or La; the magnesium content of the metallic magnesium is 99.85-99.95%.

[0008] In some embodiments, the purity of the high-temperature aluminum melt is ≥99.85%.

[0009] The refining agents described in this application include KCl, MgCl2 or BaCl2.

[0010] In some embodiments, the purity of the high-purity argon gas is ≥99.99%.

[0011] In some embodiments, the semi-continuous casting employs heightened graphite rings, which are split double graphite ring structures comprising an oil ring and a gas ring, with a seal between the oil ring and the gas ring, preventing them from communicating with each other.

[0012] In some embodiments, casting cooling water is sprayed through a double row of cooling water holes at different angles.

[0013] In some embodiments, the homogenization process is controlled by a symmetrical hot air circulation system, an online temperature acquisition and precision control system, and a three-stage cooling system to control the temperature and cooling intensity.

[0014] In some embodiments, the aluminum alloy ingot is loaded into the furnace at a furnace gas temperature of 120-180°C, and after the metal temperature reaches 270-280°C, it is held at that temperature for 8-12 hours before being heated to a constant temperature until the metal temperature reaches 440-480°C, and then held at that temperature for 30-40 hours.

[0015] Compared with the prior art, the aluminum alloy ingot for marine engineering and its production method described in this application have the following advantages: (1) The aluminum alloy ingot billet and production method for marine engineering in this application completely solves the problem of difficult forming of high magnesium and high silicon aluminum alloy ingot billets under industrial conditions, and the metallurgical defects such as central cracks, coarse grains and surface inclusions in the ingots, which lead to unqualified ingot billet quality. The casting qualification rate of large-size ingot billets is increased to 100%; the hydrogen content of the melt is ≤0.11ml / 100gAl.

[0016] (2) During the casting process, by increasing the height of the graphite ring, the lubrication stroke is increased, the oil and gas output is stabilized, and sufficient lubrication is provided at the same time to reduce stress concentration during the casting stretching process and reduce the occurrence of cracking and aluminum leakage. By changing the graphite ring to a split structure of oil ring and gas ring, the oil ring is dedicated to oil supply and the gas ring is dedicated to gas supply. The two are equipped with a seal to ensure that they are not connected to each other, which effectively solves the problem of lubricating oil blocking lubricating gas and greatly improves the appearance quality of aluminum alloy ingots for marine engineering.

[0017] (3) The design of double-row cooling water holes with different angles changes the cooling water spray angle, reduces the intensity of secondary cooling during the aluminum alloy ingot casting process, avoids local extreme cooling of the aluminum alloy ingot for marine engineering, and prevents cracking of the aluminum alloy ingot; at the same time, it maintains a relatively stable temperature difference between the inside and outside of the aluminum alloy ingot, ensures the uniformity and stability of the internal structure, and makes the surface and internal quality of the aluminum alloy ingot for marine engineering better.

[0018] (4) By designing a symmetrical hot air circulation system, an online acquisition and precise control system for the temperature of alloy bars in the homogenizing furnace, and a three-stage cooling system for aluminum alloy bars, the temperature and cooling intensity control during the homogenization process of aluminum alloy ingots for marine engineering has been improved. The product strength performance has been improved by approximately 20-30 MPa. Detailed Implementation

[0019] The embodiments of this application are described in detail below, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application.

[0020] In the description of this specification, references to "an embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Descriptions involving "first," "second," etc., in this application are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of indicated technical features. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0021] The present application is further illustrated below with reference to embodiments, but this does not limit the scope of protection of the technical solution of the present application.

[0022] This application discloses an aluminum alloy ingot for marine engineering, the chemical composition of which, by mass percentage, is: 0.7%-4.8%Mg, 1.0%-1.1%Si, 0.2%-0.8%Mn, 0.07-0.2%Zr, 0.10%-0.20%Er, 0.03%-0.05%Ti, 0.06%-0.12%Cu, Fe≤0.16%, Zn≤0.05%, with the balance being Al.

[0023] The production method of the above-mentioned aluminum alloy ingot is as follows: (1) Material addition: According to the planned aluminum input, a certain amount of aluminum-manganese master alloy, rare earth master alloy, metallic magnesium and recycled materials are added to the aluminum alloy smelting furnace in advance to complete the material preparation before smelting; the high-temperature aluminum liquid produced by aluminum electrolysis is transferred to the aluminum alloy smelting furnace by vacuum aluminum ladle to achieve non-contact and low-loss transfer of high-temperature aluminum liquid. (2) Smelting and refining: The high-temperature aluminum liquid described in step (1) is transferred to the aluminum alloy smelting furnace. During the transfer and injection of the high-temperature aluminum liquid into the smelting furnace, the electromagnetic stirring is turned on for stirring. Aluminum manganese master alloy, rare earth master alloy, metallic magnesium and recycled material are added in advance. The recycled material is the scrap material from the aluminum alloy ingot production process. During the melting process, the synergistic effect of the turbulent flow of aluminum liquid and electromagnetic stirring is used to make the added components evenly dispersed in the aluminum alloy melt to ensure that the elements are evenly distributed. After all the added materials have completely melted, turn off the electromagnetic stirring and control the temperature of the aluminum alloy melt at 780-790℃. Maintain this temperature for constant temperature melting for 20-30 minutes. During this process, through continuous temperature compensation, the alloy melt is kept in thermodynamic equilibrium, allowing all alloying elements to diffuse fully. Constant temperature helps to eliminate local concentration fluctuations, reduce segregation tendency, and also facilitates the flotation and precipitation of non-metallic inclusions, ultimately forming an aluminum alloy melt with stable composition and high homogeneity. Adjust the composition according to the requirements of the aluminum alloy ingot billet, introduce high-purity argon into the melting furnace at a temperature of 740-750℃, and add refining agent for refining treatment for 10-15 minutes to remove impurities in the melt.

[0024] (3) Semi-continuous casting: The aluminum alloy melt obtained from the refining process in step (2) is allowed to stand for 20-30 minutes; using the double graphite ring casting process, Al-Ti wire is first added according to the process requirements during the casting process. Preferably, the Ti content in the Al-Ti wire is 5-7%. By introducing Al-Ti wire, the aluminum alloy melt is subjected to grain refinement treatment, thereby improving the mechanical properties and processing performance of the aluminum alloy ingot. The semi-continuous casting process parameters are controlled as follows: casting speed is 50-80 mm / min, casting temperature is 710-730℃, and casting cooling water pressure is 0.03-0.10 MPa. After the casting process is stable, the casting speed is adjusted to 400-600 mm / min to carry out the semi-continuous casting process and obtain the aluminum alloy ingot. (4) Homogenization treatment: The aluminum alloy ingot obtained in step (3) and qualified by appearance inspection is loaded into the hot air circulation homogenization furnace for homogenization treatment. The hot air circulation homogenization furnace performs uniform heat treatment on the aluminum alloy ingot. By precisely controlling the temperature and gas flow in the furnace, the alloy elements are evenly distributed, thereby improving the internal structure quality and mechanical properties of the aluminum alloy ingot for shipbuilding and marine engineering.

[0025] In step (1) above, the manganese content of the aluminum-manganese master alloy is 1.2-1.6%; the rare earth content of the rare earth master alloy is 5-10%, and the rare earth elements are mainly Ce, La, etc.; the magnesium content of the metallic magnesium is 99.85-99.95%; the recycled material is the scrap material from the production process of aluminum alloy ingot billets for shipbuilding and marine engineering; and the high-temperature aluminum liquid is produced by an electrolytic plant with a purity ≥99.85%.

[0026] The refining agent in step (2) above is composed of KCl, MgCl2 or BaCl2; the refining agent is a purchased product or obtained by conventional means, and the purity of the argon gas is ≥99.99%.

[0027] In step (3) above, the height of the graphite ring is increased to enhance the lubrication stroke, stabilize oil and gas output, and provide sufficient lubrication, thereby reducing stress concentration during casting and stretching, and minimizing the occurrence of cracking and aluminum leakage. Semi-continuous casting is employed, and the graphite ring structure is modified to a split-type double graphite ring structure, including an oil ring and a gas ring. The split design enables independent operation of oil and gas supply. The oil ring is dedicated to oil supply, and the gas ring is dedicated to gas supply, with a seal between them to ensure they are not interconnected. The seal between the oil ring and the gas ring effectively blocks the flow path between lubricating oil and gas, completely solving the technical problem of lubricating oil clogging the lubricating gas in traditional integrated graphite rings, reducing casting defects caused by gas channel blockage, and significantly improving the appearance quality of aluminum alloy ingots for marine engineering.

[0028] In step (3) above, the design of double-row cooling holes at different angles alters the cooling water spray angle, thus reducing the intensity of secondary cooling during the casting process. This design prevents the aluminum alloy ingot from being subjected to localized extreme cooling, which could cause cracking. Simultaneously, by optimizing the cooling intensity, the temperature difference between the inside and outside of the aluminum alloy ingot can be maintained within a relatively stable and reasonable range, ensuring the uniformity and stability of the internal structure of the aluminum alloy ingot, resulting in superior surface and internal quality.

[0029] The above step (4) provides a symmetrical hot air circulation homogenization process. By designing a symmetrical hot air circulation system, an online acquisition and precise control system for the temperature of alloy rods in the homogenization furnace, and a three-stage cooling system, the temperature and cooling intensity of the aluminum alloy ingot billet are precisely controlled during the processing. First, the aluminum alloy ingot billet is loaded into the furnace at a furnace gas temperature of 120-180℃. The homogenization furnace is heated by the symmetrical hot air circulation system. The metal temperature of the aluminum alloy ingot billet is monitored in real time by the online acquisition and precise control system for the temperature of alloy rods in the homogenization furnace. When the metal temperature of the aluminum alloy ingot billet reaches 270-280℃, it is held for 8-12 hours. After the first stage of holding is completed, the temperature of the homogenization furnace is adjusted to 450-480℃ by continuing to raise the temperature through the symmetrical hot air circulation system. When the metal temperature of the aluminum alloy ingot billet reaches 440-480℃, it is held for 30-40 hours. After the second stage of heat preservation is completed, the three-stage cooling system for the aluminum alloy ingot is activated. This three-stage cooling includes three cooling phases: first, cooling is used to bring the metal temperature of the ingot to 250-300℃ for 40-50 minutes; then, water mist cooling is used to bring the metal temperature to 50-100℃; finally, water cooling is used to bring the metal temperature to room temperature for 10-20 minutes. Based on the material characteristics of the ingot and subsequent processing requirements, the cooling intensity is adjusted through a precise control system to complete the homogenization cooling treatment of the aluminum alloy ingot for marine engineering.

[0030] Example 1 A method for producing aluminum alloy ingots (2xxx, 5xxx, 6xxx) for marine engineering includes the following steps: (1) Material addition: According to the planned amount of aluminum, a certain amount of aluminum-manganese master alloy with a manganese content of 1.2%, rare earth Al-Ce master alloy, 99.85% metallic magnesium and recycled material are added to the aluminum alloy smelting furnace in advance; then the high-temperature aluminum liquid produced by aluminum electrolysis is transferred to the aluminum alloy smelting furnace using a vacuum aluminum ladle.

[0031] (2) Melting and refining: During the process of transferring the high-temperature aluminum liquid to the aluminum alloy melting furnace, the aluminum alloy melt is electromagnetically stirred at the same time; then, the aluminum alloy melt is melted at 780℃ for 20 minutes; the composition is adjusted according to the requirements, and high-purity argon gas and refining agent KCl are introduced for refining for 10 minutes.

[0032] (3) Semi-continuous casting: Under the condition of a temperature of 740℃, the aluminum alloy melt with qualified composition obtained in step (2) is introduced into a settling furnace, and after refining with high-purity argon and KCl for 10 minutes, it is settling for 20 minutes; then, under the conditions of a casting speed of 50 mm / min, a casting temperature of 710℃, and a casting cooling water pressure of 0.03 MPa, Al-Ti wire with a Ti content of 6% is added, and the casting cooling water is sprayed through double rows of cooling water holes with different angles. Semi-continuous casting is carried out under the condition of a casting speed of 400 mm / min, and the casting process is independently supplied with oil and gas to obtain aluminum alloy ingot billets.

[0033] (4) Homogenization treatment: The aluminum alloy billets that have passed the appearance inspection are loaded into the homogenization furnace, heated to 540℃-580℃ and held for 8-12 hours, air-cooled for 190-220 minutes, and water-cooled for 70-90 minutes. Temperature and cooling intensity are controlled by a symmetrical hot air circulation system, an online temperature acquisition and precise control system, and a three-stage cooling system.

[0034] The aluminum alloy ingots prepared in Example 1 were tested for their chemical composition, mechanical properties, and internal structure. The casting pass rate of this batch of large-size ingots was 100%.

[0035] The mechanical properties of the aluminum alloy ingot blanks prepared in Example 1 were tested, and the test results are shown in the table below.

[0036]

[0037] In summary, the aluminum alloy ingot billet and production method for marine engineering in this application significantly improve the appearance quality of the aluminum alloy ingot billet, making the surface and internal quality better, while increasing the strength performance of the aluminum alloy ingot billet by about 20-30 MPa, increasing the casting qualification rate of large-scale cast billets to 100%, and the hydrogen content of the melt is ≤0.11 ml / 100gAl.

[0038] The above description is only a partial embodiment of this application. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of this application, and these improvements and modifications should also be considered within the scope of protection of this application.

Claims

1. A type of aluminum alloy casting billet for marine engineering, characterized in that, Its chemical composition by mass percentage is: 0.7-4.8% Mg, 1.0-1.1% Si, 0.2-0.8% Mn, 0.07-0.2% Zr, 0.10-0.20% Er, 0.03-0.05% Ti, 0.06-0.12% Cu, Fe≤0.16%, Zn≤0.05%, with the balance being Al.

2. The method for producing aluminum alloy ingots for marine engineering according to claim 1, characterized in that, Includes the following steps: (1) Material addition: According to the planned aluminum input, a certain amount of aluminum-manganese master alloy, rare earth master alloy, metallic magnesium and recycled material are added to the aluminum alloy smelting furnace in advance; then the high-temperature aluminum liquid produced by aluminum electrolysis is transferred to the aluminum alloy smelting furnace using a vacuum aluminum ladle. (2) Smelting and refining: During the process of transferring the high-temperature aluminum liquid to the aluminum alloy smelting furnace, the aluminum alloy melt is simultaneously electromagnetically stirred; Then, the aluminum alloy melt is melted at 780-790℃ for 20-30 minutes; the composition is adjusted according to requirements, and high-purity argon and refining agent are introduced for refining for 10-15 minutes. (3) Semi-continuous casting: Under the condition of a temperature of 740-750℃, the aluminum alloy melt with qualified composition obtained in step (2) above is introduced into a settling furnace, and the high-purity argon gas and the refining agent are introduced for refining for 10-15 minutes, and then settling for 20-30 minutes; then Al-Ti wire is added under the conditions of casting speed of 50-80mm / min, casting temperature of 710-730℃, and casting cooling water pressure of 0.03-0.10MPa, and semi-continuous casting is carried out under the condition of casting speed of 400-600mm / min. The casting process is independently supplied with oil and gas to obtain aluminum alloy ingot billet; (4) Homogenization treatment: The aluminum alloy ingot billet that has passed the appearance inspection is loaded into a hot air circulating homogenization furnace for homogenization treatment.

3. The method for producing aluminum alloy ingots for marine engineering according to claim 2, characterized in that: By mass percentage, the manganese content of the aluminum-manganese master alloy in step (1) is 1.2-1.6%; the rare earth content of the rare earth master alloy is 5-10%, and the rare earth elements include Ce or La; the magnesium content of the metallic magnesium is 99.85-99.95%.

4. The method for producing aluminum alloy ingots for marine engineering according to claim 2, characterized in that: The purity of the high-temperature aluminum liquid in step (1) is ≥99.85%.

5. The method for producing aluminum alloy ingots for marine engineering according to claim 2, characterized in that: The refining agent in step (2) includes KCl, MgCl2 or BaCl2.

6. The method for producing aluminum alloy ingots for marine engineering according to claim 2, characterized in that: The purity of the high-purity argon gas in step (2) is ≥99.99%.

7. The method for producing aluminum alloy ingots for marine engineering according to claim 2, characterized in that: In step (3), the semi-continuous casting adopts a heightened graphite ring. The graphite ring is a split double graphite ring structure, which includes an oil ring and a gas ring. A sealing element is installed between the oil ring and the gas ring, and they are not connected to each other.

8. The method for producing aluminum alloy ingots for marine engineering according to claim 2, characterized in that: In step (3), the casting cooling water is sprayed through double rows of cooling water holes at different angles.

9. The method for producing aluminum alloy ingots for marine engineering according to claim 2, characterized in that: In step (4), the homogenization process is controlled by a symmetrical hot air circulation system, an online temperature acquisition and precise control system, and a three-stage cooling system to control the temperature and cooling intensity.

10. The method for producing aluminum alloy ingots for marine engineering according to claim 2, characterized in that: The aluminum alloy ingot billet after step (4) is placed in the furnace at a furnace gas temperature of 120-180℃. When the metal temperature reaches 270-280℃, it is held for 8-12 hours and then heated to a constant temperature until the metal temperature reaches 440-480℃. It is then held for 30-40 hours.

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