High-strength corrosion-resistant marine aluminum alloy profile and preparation method thereof

Abstract

This invention relates to the field of aluminum alloy material processing, specifically to a high-strength, corrosion-resistant marine aluminum alloy profile and its preparation method. The components and their weight percentages in this profile are as follows: Si content 0.16-0.20%; Fe content 0.24-0.26%; Cu content 0.05-0.15%; Mn content 0.6-0.8%; Mg content 4.7-4.9%; Cr content 0.05-0.25%; Zn content 0.15-0.25%; Zr content... The content of the alloy is 0.05-0.12%; the content of Ti is 0.01-0.012%; the content of B is 0.001-0.0025%; the content of other impurity elements is ≤0.05% for each individual element; the total content of other impurity elements is ≤0.15%; the balance is Al; the weight percentage ratio of Ti to B is 5.2-5.7:1, and the weight percentage ratio of Zr to B is 22-55:1. This profile is a marine aluminum alloy profile with high strength and high corrosion resistance, which meets the development needs of the shipbuilding industry.

Description

Technical Field

[0001] This invention relates to the field of aluminum alloy material processing, specifically to a high-strength corrosion-resistant marine aluminum alloy profile and its preparation method. Background Technology

[0002] In recent years, with the shipbuilding industry developing towards larger, more efficient, and greener designs, aluminum alloys, with their excellent corrosion resistance and significant lightweight properties, have become a core material in shipbuilding (such as hull structures, deck components, and bulkhead systems). In particular, 5083 alloy, due to its Al-Mg-Mn phase formed by magnesium (Mg) and manganese (Mn), effectively resists seawater corrosion while meeting the need for weight reduction and improved fuel efficiency, leading to its increasingly widespread application in marine engineering. However, existing 5083 aluminum alloys still face many technical bottlenecks in practical applications. In large ship construction and extreme sea conditions (such as polar navigation), its strength is insufficient to meet stringent mechanical performance requirements. Traditional cold working strengthening processes can improve strength but inevitably sacrifice material plasticity, while conventional heat treatment methods may lead to a decrease in corrosion resistance. Currently, there is a lack of effective means to synergistically optimize strength and plasticity. Furthermore, in environments rich in Cl... - In marine environments, although 5083 aluminum alloy has certain natural corrosion resistance, after long-term service, high-stress areas (such as riveted joints) are prone to pitting corrosion and stress corrosion cracking. Existing surface treatment technologies, such as anodizing, are not only complex and costly, but also have problems such as insufficient environmental protection.

[0003] Therefore, there is an urgent need to provide an aluminum alloy profile that combines mechanical strength and corrosion resistance, as well as its preparation method. Summary of the Invention

[0004] The present invention aims to solve the technical problem of how to provide an aluminum alloy profile with both mechanical strength and corrosion resistance, and the method for preparing the same.

[0005] To achieve the above objectives, the first aspect of the present invention provides a high-strength, corrosion-resistant marine aluminum alloy profile, wherein the components and their weight percentages in the profile are as follows: The Si content is 0.16-0.20%; The Fe content is 0.24-0.26%; The Cu content is 0.05-0.15%; The Mn content is 0.6-0.8%; The Mg content is 4.7-4.9%; The Cr content is 0.05-0.25%; The Zn content is 0.15-0.25%; The Zr content is 0.05-0.12%; The Ti content is 0.01-0.012%; The content of B is 0.001-0.0025%; The content of other impurity elements is ≤0.05%; The total content of other impurity elements is ≤0.15%; The balance is Al; The weight percentage ratio of Ti to B is 5.2-5.7:1, and the weight percentage ratio of Zr to B is 22-55:1.

[0006] A second aspect of the present invention provides a method for preparing the above-mentioned high-strength corrosion-resistant marine aluminum alloy profile, wherein the method includes: Smelting, casting, homogenization, extrusion, annealing; The casting conditions include: the temperature at the tail of the casting pan is 675-685℃, and a gradient cooling crystallizer is used, which includes an upper section, a middle section and a lower section of the crystallizer. A scraper is used to prevent the cooling water in the upper section of the crystallizer from flowing through the middle and lower sections of the crystallizer, and the cooling water in the middle section of the crystallizer from flowing through the lower section of the crystallizer. The upper section of the crystallizer is a strong cooling zone with a length l1 of 100-150mm, and the cooling water volume accounts for 40-50% of the total cooling water volume. The middle section of the crystallizer is a slow cooling zone with a length l2 of 150-200 mm, and the cooling water volume accounts for 30-40% of the total cooling water volume. The lower section of the crystallizer is a heat preservation zone with a length l3 of 50-100 mm, and the cooling water volume accounts for 20-30% of the total cooling water volume. The velocity of the melt within the crystallizer, ʋ, and the residence time of the melt within the crystallizer, t. i The relationship is: l i =ʋ×t i Where i = 1, 2, 3, and t is the residence time t in the crystallizer. i The unit is seconds (s). t1 is the residence time of the melt in the upper section of the crystallizer, which is 20-30% of the total solidification time. t2 is the residence time of the melt in the middle section of the crystallizer, which is 40-50% of the total solidification time. t3 is the residence time of the melt in the lower section of the crystallizer, which is 20-30% of the total solidification time. The unit of the melt's movement speed ʋ in the crystallizer is mm / s.

[0007] The beneficial effects of this invention are as follows: The profiles provided by this invention can achieve multi-objective optimization of "strength and toughness, corrosion resistance and processability" through element ratio and specific casting process and crystallizer. The resulting aluminum alloy profiles have both excellent mechanical strength and corrosion resistance. Furthermore, by using a specific extrusion process, the resulting aluminum alloy profiles can have even better mechanical strength and corrosion resistance. Attached Figure Description

[0008] Figure 1 This is a surface quality diagram of the profile in Example 1.

[0009] Figure 2 The surface quality diagram is for the profile in Comparative Example 1.

[0010] Figure 3 This is a diagram showing the depth of corrosion pits in the profile of Example 1.

[0011] Figure 4 This is a diagram showing the depth of corrosion pits on the profile shown in Comparative Example 3. Detailed Implementation

[0012] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0013] In the existing technology, the marine aluminum alloy profiles produced cannot meet the requirements of having both high strength and high corrosion resistance.

[0014] In this invention, the inventors discovered that by controlling the alloy composition and adjusting the processing technology, the performance of marine aluminum alloy profiles can meet the requirements, possessing both high strength and high corrosion resistance.

[0015] To achieve this goal, the inventors attempted to optimize the composition and processing technology of each component of the aluminum alloy profile. The inventors discovered that the above objectives could be achieved through specific component compositions, casting processes, and crystallizers. Furthermore, specific homogenization and annealing processes made the aluminum alloy profiles perform even better.

[0016] The first aspect of this invention provides a high-strength, corrosion-resistant marine aluminum alloy profile, wherein the components and their weight percentages in the profile are as follows: The Si content is 0.16-0.20%; The Fe content is 0.24-0.26%; The Cu content is 0.05-0.15%; The Mn content is 0.6-0.8%; The Mg content is 4.7-4.9%; The Cr content is 0.05-0.25%; The Zn content is 0.15-0.25%; The Zr content is 0.05-0.12%; The Ti content is 0.01-0.012%; The content of B is 0.001-0.0025%; The content of other impurity elements is ≤0.05%; The total content of other impurity elements is ≤0.15%; The balance is Al; The weight percentage ratio of Ti to B is 5.2-5.7:1, and the weight percentage ratio of Zr to B is 22-55:1.

[0017] In this invention, the boron element is added in a mixture of Al-5Ti-B and Al-3Ti-0.5B; the Ti:B ratio is added between 5.2:1 and 5.7:1. Excess Ti leads to coarsening of Al3Ti, exceeding the requirement for combining with B to form TiB2. The excess Ti precipitates as the Al3Ti phase, which is a coarse, plate-like or blocky compound. It not only cannot serve as a nucleation core but also becomes a stress concentration point, cutting the matrix and reducing the plasticity and toughness of the alloy. At the same time, it makes the ingot prone to cracking during processing. Excess Ti inhibits the nucleation of TiB2, and the coarsening of Al3Ti consumes some Ti, indirectly reducing the number of effective nucleation particles TiB2, resulting in a weakened grain refinement effect, difficulty in suppressing columnar crystals, and the appearance of coarse equiaxed or columnar crystals in the as-cast structure, thus reducing the nucleation efficiency.

[0018] When the Zr / B ratio exceeds a certain range, Zr becomes excessive, and the synergistic effect of Ti, B, and Zr fails. Zr can improve nucleation efficiency by forming (Ti,Zr)B2 composite particles, but excessive Zr consumes more B, and Ti preferentially forms Al3Ti, reducing the chance of Zr combining with Ti and B. This prevents Zr from playing its compensatory role and further exacerbates insufficient nucleation. When the Zr / B ratio is less than a certain range, Zr is too low to fully combine with B, and excess B leads to increased TiB2 particle size and aggregation. After TiB2 aggregation, the dispersion of nucleation cores deteriorates, and coarse grains form in local areas due to the lack of effective nucleation sites. Furthermore, the aggregated TiB2 becomes brittle inclusions, reducing the fatigue performance and machinability of the alloy, and making it prone to microcracks during rolling.

[0019] The addition of Zr / B within a defined ratio aims primarily to refine the crystal structure, promote the formation of equiaxed crystals, inhibit the formation of columnar crystals, and prevent TiB2 aggregation or Al3Ti coarsening. Zr can form (Ti,Zr)B2 or TiB2 / Al3Zr composite particles with Ti and B, exhibiting higher nucleation efficiency than TiB2 alone. Zr can also compensate for some of the nucleation effect of B, preventing Al3Ti coarsening caused by excessive Ti.

[0020] According to the present invention, the weight percentage ratio of Mg / Mn / Fe is 1:(0.12-0.19):(0.05-0.06).

[0021] In this invention, the ratio of Mg / Mn / Fe is controlled. An appropriate amount of Mg can ensure that the alloy has good plasticity, but an excessive amount will increase brittleness. High Mg content will reduce the stress corrosion resistance of the alloy and easily form the Mg5Al6 phase, leading to an increased tendency for intergranular corrosion. Therefore, it is necessary to control the ratio of Mg to Mn to ensure that Mn can fully combine with Fe to form the Al6(Mn,Fe) phase and avoid Fe from precipitating as a needle-like phase. High Mg content needs to be combined with appropriate Mn to avoid brittleness caused by excessive Mg. At the same time, the strengthening effect of Mn is used to compensate for the lack of strengthening by Mg alone and improve the processing performance of the alloy.

[0022] A second aspect of the present invention provides a method for preparing the above-mentioned high-strength corrosion-resistant marine aluminum alloy profile, wherein the method includes: Smelting, casting, homogenization, extrusion, annealing; The casting conditions include: the temperature at the tail of the casting pan is 675-685 ℃, and a gradient cooling crystallizer is used, which includes an upper section, a middle section and a lower section of the crystallizer. A scraper is used to prevent the cooling water in the upper section of the crystallizer from flowing through the middle and lower sections of the crystallizer, and the cooling water in the middle section of the crystallizer from flowing through the lower section of the crystallizer. The upper section of the crystallizer is a strong cooling zone with a length l1 of 100-150 mm, and the cooling water volume accounts for 40-50% of the total cooling water volume. The middle section of the crystallizer is a slow cooling zone with a length l2 of 150-200 mm, and the cooling water volume accounts for 30-40% of the total cooling water volume. The lower section of the crystallizer is a heat preservation zone with a length l3 of 50-100 mm, and the cooling water volume accounts for 20-30% of the total cooling water volume. The velocity of the melt within the crystallizer, ʋ, and the residence time of the melt within the crystallizer, t. i The relationship is: l i =ʋ×t i Where i = 1, 2, 3, and t is the residence time t in the crystallizer. iThe unit is seconds (s). t1 is the residence time of the melt in the upper section of the crystallizer, which is 20-30% of the total solidification time. t2 is the residence time of the melt in the middle section of the crystallizer, which is 40-50% of the total solidification time. t3 is the residence time of the melt in the lower section of the crystallizer, which is 20-30% of the total solidification time. The unit of the melt's movement speed ʋ in the crystallizer is mm / s.

[0023] In this invention, the structure of the crystallizer is the same as that of conventional aluminum alloy casting crystallizers in the art. The side wall of the crystallizer is provided with a water inlet. The upper, middle and lower sections of the crystallizer are respectively connected to their own independent water inlet pipes to adjust the flow rate and velocity parameters of the cooling water. The three water inlet pipes are connected to the main pipe, and the cooling water flow rate of each pipe is adjusted by a flow controller.

[0024] In this invention, given the difficulty in controlling the Ti to B ratio, which easily leads to microstructural defects, and the tendency for the synergistic effect of Zr to fail, exacerbating insufficient nucleation, a gradient cooling crystallizer is employed, and the temperature of the casting pan tail plate is controlled, which can reduce microstructural defects and performance fluctuations.

[0025] The length l1 of the upper section of the specific crystallizer needs to cover the solidification region corresponding to the thickness of the surface chilled layer. This is a parameter range obtained after adjustments based on the solidification transition zone, interface fluctuation compensation, cooling response hysteresis, alloying degree, and surface quality requirements. The high-temperature melt first contacts the chilled zone, and the surface layer rapidly cools to form a fine equiaxed crystal shell (chilled layer). The low temperature and large water volume increase the temperature gradient at the solidification front, inhibiting free dendrite growth and thus reducing columnar crystal elongation. Combined with the nucleation effect of Ti-B-Zr, this enhances the grain refinement effect. The length l2 of the middle section of the specific crystallizer needs to balance the solidification thickness and the requirements for equiaxed crystal growth, ensuring… The uniform grain size and slow cooling create a wide supercooled zone at the solid-liquid interface, providing growth space for free crystal nuclei, promoting the uniform distribution and formation of equiaxed crystals. The lower section of the specific crystallizer is a heat preservation zone after the melt has completely solidified. Its length l3 needs to meet the requirements of heat preservation and complete solidification, reducing internal stress in the casting and avoiding cracking caused by rapid cooling. The lower part of the cast rod has entered the solid-state cooling stage. The heat preservation zone reduces the cooling intensity, making the temperature field uniform and avoiding thermal stress cracks caused by excessive internal and external temperature differences. The specific upper, middle and lower sections of the crystallizer in this invention realize the process of rapid quenching, stable solidification and slow cooling heat preservation.

[0026] Conventional crystallizer cooling suffers from defects in solidification structure. Cooling intensity crosstalk leads to insufficient cooling rate in the upper section, failing to form a uniform chilled layer; excessively high cooling rate in the lower section easily causes shrinkage cavities / cracks in the core, resulting in a high proportion of columnar crystals, often exceeding 30%, with coarse and uneven grains. Due to the lack of a clear cooling intensity gradient, performance fluctuates greatly, with significant deviations in the mechanical properties of the same batch of cast rods. Segmented cooling, through physical isolation (scraper + independent controlled cooling water flow), fundamentally solves the four major problems of traditional continuous cooling: "cooling intensity crosstalk, uncontrolled water volume ratio, failure of water temperature gradient, and equipment corrosion and scaling." Ultimately, it achieves uniformity in cast rod structure, ensures accurate design proportions, and comprehensively improves dimensional accuracy and mechanical properties.

[0027] The tail of the casting pan refers to the temperature parameters of the tail region after the ingot is cast during the opening and closing stages of a single casting cycle.

[0028] The total solidification time is the total time required for the melt to complete the entire solidification process (i.e., completely transform from a liquid to a solid state) from the moment it enters the crystallizer, and its value is equal to the sum of the residence times of the melt in the upper, middle, and lower sections of the crystallizer (t). 总 =t1+t2+t3).

[0029] In this invention, to meet the requirement of slow cooling, the water volume ratio in the middle section is higher than the length ratio in the middle section.

[0030] According to the present invention, the relationship between the length l2 of the middle section of the crystallizer and the radius R of the casting rod is l2 = (0.8R - 10) × n, where R is 99-111 mm and n is 1.8-2.2.

[0031] In this invention, the relationship between the length l2 of the middle section of the crystallizer and the radius R of the casting rod is derived from the interface propulsion speed and cooling efficiency.

[0032] According to the present invention, the smelting conditions include: the relationship between the feeding rate a1 of the intermediate alloy Al-5Ti-B and the feeding rate a2 of the intermediate alloy Al-3Ti-0.5B is as follows: =y, where y is the weight percentage ratio of Ti to B in the high-strength corrosion-resistant marine aluminum alloy profile, which is 5.2-5.7:1.

[0033] According to the present invention, the casting release time is 20-40 minutes.

[0034] In this invention, the relationship between the addition rate a1 of the specific intermediate alloy Al-5Ti-B and the addition rate a2 of the intermediate alloy Al-3Ti-0.5B is utilized. By adjusting the mixing ratio of Al-5Ti-1B and Al-3Ti-0.5B, the B content in the melt is controlled at 0.001-0.0025%, with a control deviation of ±0.0005%. This precise control of the B element content ensures that the B content remains within the target range, preventing the loss of grain refinement effect due to excessively low B content, which would significantly reduce corrosion resistance. Conversely, excessive B element would lead to decreased corrosion performance due to grain coarsening and galvanic effect. This achieves the synergistic effect of Zr and other components such as B. Furthermore, the use of dual titanium wire technology forms nanoscale TiB2 heterogeneous nucleation cores, thereby realizing Ti-B composite refinement.

[0035] According to the present invention, the smelting conditions further include: preheating the raw materials and intermediate alloy at 150-200°C, smelting furnace temperature at 850-950°C, online refining, online degassing, and online filtration of the melt, followed by electromagnetic stirring, slag removal, standing for 30-45 minutes, and semi-continuous casting at an aluminum melt temperature of 715-740°C.

[0036] According to a specific embodiment of the present invention, the raw materials and intermediate alloys are preheated at 150-200°C for surface drying. First, 99.70% Al is added, and the furnace temperature is set to 850-950°C. After the aluminum ingots are completely melted, when the aluminum liquid temperature is 750-780°C at the initial stage of melting, Al-5%Zr intermediate alloy is added. The intermediate alloy is fully melted by stirring. When the aluminum liquid temperature is 710-730°C, industrial Si, Al-20%Fe, Al-60%Cu, Al-20%Mn, Al-5%Cr, and Zn ingots are added. After complete melting, Mg ingots are added. Degassing and refining are performed using a powder spraying method (99.9% pure argon + granular refining agent), and surface slag is removed by mechanical slag removal. The settling time is 30-45 minutes. Semi-continuous casting is performed when the aluminum liquid temperature is 715-740°C. After the melt enters the ladle, electromagnetic stirring (10) is first activated. Pre-stir for 30-60 seconds (Hz); then feed in the mixed titanium wire while maintaining electromagnetic stirring to ensure rapid and uniform Ti distribution.

[0037] The online purification system includes a graphite rotor degasser (degassing efficiency ≥50%) and a two-stage filtration device (foam ceramic filter plates 30ppi + 50ppi).

[0038] According to the present invention, the homogenization treatment conditions include: the homogenization treatment process is (500-510℃) × (8-12h) + (400-450℃) × (10-16h).

[0039] In this invention, the shortcomings of traditional single-temperature homogenization lead to a contradiction between element diffusion and precipitation. Traditional homogenization often uses a single high-temperature (e.g., 490-510℃) holding temperature. Although this can promote the diffusion of elements such as Mg and Mn from the dendritic segregation zone to the matrix and eliminate compositional segregation, the high temperature can easily lead to the formation of strengthening phases such as Zr and Cr (e.g., excessive coarsening of Al3Zr, reducing its pinning effect on dislocations; some Mg elements prematurely accumulate at grain boundaries, forming coarse β phases (Al3Mg2), which in turn reduces the alloy's corrosion resistance and subsequent processing performance. The cast rod contains original casting stress. When rapidly cooled after a single high-temperature holding temperature, the large temperature difference between the inside and outside can easily generate new thermal stress and even induce microcracks.

[0040] High-temperature conditions (500-510℃) significantly improve the atomic diffusion coefficient, alleviating the segregation of Ti, B, and Zr caused by rapid solidification during casting (such as grain boundary enrichment and interdendritic segregation). Ti and Zr, as transition metals, readily form coarse intermetallic compounds (such as Al3Ti and Al3Zr) at grain boundaries, which can partially dissolve or break down at high temperatures, reducing damage to the matrix. B often exists as borides (such as TiB2), which, while relatively stable at high temperatures, can react with the TiB2 interface through Ti diffusion in the matrix, optimizing its spatial distribution with Zr (e.g., allowing Zr to diffuse more uniformly around TiB2 particles). At high temperatures, Ti and B have strong bonding (TiB2 has a lower enthalpy of formation), preferentially forming a stable TiB2 core. Zr, as a slower-diffusion element, forms a gradient-distributed solid solution region around TiB2, creating "pre-enrichment" conditions for subsequent low-temperature synergistic precipitation. The core function of the low-temperature stage is to regulate the precipitation morphology and interface synergy, control the precipitation morphology of Ti and Zr, and enhance the interface matching with B.

[0041] The low-temperature range (400-450℃) is the key stage for the precipitation of Ti and Zr from the supersaturated solid solution. At this time, Ti tends to precipitate as fine Al3Ti or Al3(Ti,Zr) phase coherent with Zr. The B-stable TiB2 particles can serve as heterogeneous nucleation nuclei for these precipitated phases, reducing the autonomous nucleation of Ti and Zr and avoiding coarse precipitates. The precipitation rate of Zr is relatively slow. At low temperatures, it can selectively precipitate at the TiB2-Ti-Al interface, forming a gradient structure of "TiB2→Ti-Al phase→Zr-Al phase", which enhances the interfacial bonding force of the three phases (reduces the interfacial energy). If treated directly at low temperatures, Ti and Zr may become locally enriched due to insufficient diffusion, forming coarse and disordered composite phases (such as the blocky phase of Al3(Ti,Zr)), which would disrupt the synergy with B. However, if the elements are homogenized by first heating at high temperatures, the low-temperature stage can be controlled by adjusting the holding time and cooling rate to guide Ti and Zr to precipitate in an ordered sequence of "Ti precipitation first, followed by Zr replenishment". Furthermore, the presence of B (such as TiB2) can act as an "anchor point", allowing Zr precipitation to be more concentrated around the strengthening phase, thus achieving a synergistic effect of "Ti-B nucleation + Zr strengthening".

[0042] According to the present invention, the extrusion conditions include: the mold heating temperature is 450-480℃, the homogenized casting rod is heated to 420-460℃, extrusion is performed, the extrusion speed is 0.5-1.5m / min, and the quenching method is water mist.

[0043] According to the present invention, the annealing conditions include: an annealing regime of (240-260)℃×(20-40min)+(280-320)℃×(50-60min)+(340-360)℃×(40-60min), followed by furnace cooling to 140-160℃ and then air cooling to 20-30℃.

[0044] In this invention, a specific annealing process is used to achieve dimensional differences in the axial crystals, thereby improving the uniformity of the microstructure.

[0045] The Mg, Mn, and Fe contents of the melt are detected using a direct-reading spectrometer. If the Fe content fluctuates by +0.05%, the Mg content is adjusted by +0.03% and the Mn content by +0.03% to maintain the Mg / Mn / Fe ratio within the range defined in this invention.

[0046] The room temperature tensile mechanical properties were tested in accordance with GB / T 228.1-2021 "Metallic materials - Tensile testing - Part 1: Room temperature test method", and the testing equipment was AG-X 100kN electronic universal testing machine.

[0047] Intergranular corrosion testing was conducted in accordance with GB / T 7998-2005 "Method for Determination of Intergranular Corrosion in Aluminum Alloys".

[0048] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Obviously, the embodiments described herein are only some embodiments of the present invention and are not intended to limit the present invention. All other embodiments implemented by those skilled in the art based on the embodiments of the present invention without creative improvements are within the protection scope of the present invention.

[0049] Example 1 The alloy is selected with the following chemical composition: Si: 0.18%, Fe: 0.25%, Cu: 0.1%, Mn: 0.8%, Mg: 4.8%, Cr: 0.10%, Zn: 0.2%, Zr: 0.10%, Ti content: 0.012%, B content: 0.0022%, other impurity element content: ≤0.05% for each individual element, ≤0.15% for the total content of other impurity elements, and the balance being Al. The Mg / Mn / Fe ratio is 4.8 / 0.8 / 0.25, Mg / Mn = 6.00:1, Mg / Fe = 19.2:1, Ti / B = 5.5:1, and Zr / B = 45:1.

[0050] Smelting: The raw materials and master alloys are preheated at 180℃ for surface drying. 99.70% Al is added first, and the furnace temperature is set to 900℃. After the aluminum ingots are completely melted, when the aluminum liquid temperature is 760℃ at the initial stage of smelting, Al-5%Zr master alloy is added. The master alloy is fully melted by stirring. When the aluminum liquid temperature is 720℃, industrial Si, Al-20%Fe, Al-60%Cu, Al-20%Mn, Al-5%Cr, and Zn ingots are added. After all the ingots have melted, Mg ingots are added. Degassing and refining are carried out using the powder spraying method (99.9% pure argon + granular refining agent). Surface slag is removed by mechanical slag removal. The settling time is 35 minutes. Semi-continuous casting is carried out when the aluminum liquid temperature is 730℃. After the melt enters the ladle, electromagnetic stirring (10 Hz) is turned on for pre-stirring for 40 seconds. Then, mixed titanium wire is fed in while maintaining electromagnetic stirring to ensure rapid and uniform distribution of Ti.

[0051] The online purification system includes a graphite rotor degasser (degassing efficiency ≥50%) and a two-stage filtration device (foam ceramic filter plates 30ppi + 50ppi).

[0052] The relationship between the feeding rate a1 of the master alloy Al-5Ti-B and the feeding rate a2 of the master alloy Al-3Ti-0.5B is as follows: =y, where y is the weight percentage ratio of Ti to B in the high-strength corrosion-resistant marine aluminum alloy profile, which is 5.5:1, and the casting release time is 30 minutes.

[0053] Casting: The temperature at the tail of the casting pan is 680 ℃, and a gradient cooling crystallizer is used. The gradient cooling crystallizer includes an upper section, a middle section and a lower section. A scraper is used to prevent the cooling water in the upper section of the crystallizer from flowing through the middle and lower sections of the crystallizer, and the cooling water in the middle section of the crystallizer from flowing through the lower section of the crystallizer. The upper section of the crystallizer is a strong cooling zone with a length l1 of 120 mm, and the cooling water volume accounts for 45% of the total cooling water volume. The middle section of the crystallizer is a slow cooling zone with a length l2 of 156 mm, and the cooling water volume accounts for 35% of the total cooling water volume. The lower section of the crystallizer is a heat preservation zone with a length l3 of 60mm, and the cooling water volume accounts for 20% of the total cooling water volume. t1 is 25% of the total solidification time, t2 is 45% of the total solidification time, and t3 is 30% of the total solidification time.

[0054] The relationship between the length l2 of the middle section of the crystallizer and the radius R of the casting rod is l2 = (0.8R - 10) × n, where R is 110 mm and n is 2.0.

[0055] Homogenization treatment: The homogenization treatment process is 510℃×10h+430℃×12h.

[0056] Extrusion: The die heating temperature is 460℃, the homogenized casting rod is heated to 440℃, and then extruded at a speed of 0.8m / min. The quenching method is water mist.

[0057] Quenching: The profile is annealed under the following conditions: 250℃ / 30min×300℃ / 40min×350℃ / 50min. After furnace cooling to 150℃, it is air-cooled to 25℃.

[0058] Aluminum alloy profile A1 was obtained.

[0059] Example 2 Aluminum alloy profiles were prepared according to the preparation method of Example 1, except that Mg 4.7%, Mn 0.7%, Fe 0.25%, Mg / Mn / Fe ratio 4.7 / 0.7 / 0.25, Mg / Mn=6.71:1, and Mg / Fe=18.8:1.

[0060] Aluminum alloy profile A2 was obtained.

[0061] Example 3 Aluminum alloy profiles were prepared according to the preparation method of Example 1, except that the alloy composition was 4.7% Mg, 0.8% Mn, 0.25% Fe, the Mg / Mn / Fe ratio was 4.7 / 0.8 / 0.25, the Mg / Mn ratio was 5.88:1, and the Mg / Fe ratio was 18.8:1.

[0062] Aluminum alloy profile A3 was obtained.

[0063] Example 4 Aluminum alloy profiles were prepared according to the preparation method of Example 1, except that the alloy composition was 4.7% Mg, 0.9% Mn, 0.25% Fe, the Mg / Mn / Fe ratio was 4.7 / 0.9 / 0.25, the Mg / Mn ratio was 5.22:1, and the Mg / Fe ratio was 18.8:1.

[0064] Aluminum alloy profile A4 was obtained.

[0065] Example 5 Aluminum alloy profiles were prepared according to the preparation method of Example 1, except that Mg 4.8%, Mn 0.7%, Fe 0.25%, Mg / Mn / Fe ratio 4.8 / 0.7 / 0.25, Mg / Mn=6.86:1, and Mg / Fe=19.2:1.

[0066] Aluminum alloy profile A5 was obtained.

[0067] Example 6 Aluminum alloy profiles were prepared according to the preparation method of Example 1, except that Mg 4.8%, Mn 0.9%, Fe 0.25%, Mg / Mn / Fe ratio 4.8 / 0.9 / 0.25, Mg / Mn=5.33:1, and Mg / Fe=19.2:1.

[0068] Aluminum alloy profile A6 was obtained.

[0069] Example 7 Aluminum alloy profiles were prepared according to the preparation method of Example 1, except that Mg 4.9%, Mn 0.7%, Fe 0.25%, Mg / Mn / Fe ratio 4.9 / 0.7 / 0.25, Mg / Mn=7.00:1, and Mg / Fe=19.6:1.

[0070] Aluminum alloy profile A7 was obtained.

[0071] Example 8 Aluminum alloy profiles were prepared according to the preparation method of Example 1, except that Mg 4.9%, Mn 0.8%, Fe 0.25%, Mg / Mn / Fe ratio 4.9 / 0.8 / 0.25, Mg / Mn=6.13:1, and Mg / Fe=19.6:1.

[0072] Aluminum alloy profile A8 was obtained.

[0073] Example 9 Aluminum alloy profiles were prepared according to the preparation method of Example 1, except that Mg 4.9%, Mn 0.9%, Fe 0.25%, Mg / Mn / Fe ratio 4.9 / 0.9 / 0.25, Mg / Mn=5.44:1, and Mg / Fe=19.6:1.

[0074] Aluminum alloy profile A9 was obtained.

[0075] Example 10 Aluminum alloy profiles were prepared according to the preparation method of Example 1, except that the B content was 0.0023%, the Ti content was 0.012%, the Ti / B ratio was 5.2:1, and the Zr / B ratio was 43:1.

[0076] Aluminum alloy profile A10 was obtained.

[0077] Example 11 Aluminum alloy profiles were prepared according to the preparation method of Example 1, except that the B content was 0.0021%, the Ti content was 0.012%, the Ti / B ratio was 5.7:1, and the Zr / B ratio was 47:1.

[0078] Aluminum alloy profile A11 was obtained.

[0079] Example 12 Aluminum alloy profiles were prepared according to the preparation method of Example 1, except that the Zr content was 0.05% and the Zr / B ratio was 22:1.

[0080] Aluminum alloy profile A12 was obtained.

[0081] Example 13 Aluminum alloy profiles were prepared according to the preparation method of Example 1, except that the Zr content was 0.12% and the Zr / B ratio was 55:1.

[0082] Aluminum alloy profile A13 was obtained.

[0083] Example 14 Aluminum alloy profiles were prepared according to the preparation method of Example 1, except that the casting disc tail temperature was 675 ℃. The upper section of the crystallizer is a strong cooling zone with a length l1 of 100 mm, and the cooling water volume accounts for 40% of the total cooling water volume. The middle section of the crystallizer is a slow cooling zone with a length l2 of 150 mm, and the cooling water volume accounts for 30% of the total cooling water volume. The lower section of the crystallizer is a heat preservation zone with a length l3 of 50 mm, and the cooling water volume accounts for 30% of the total cooling water volume. t1 is 30% of the total solidification time, t2 is 50% of the total solidification time, and t3 is 20% of the total solidification time.

[0084] Aluminum alloy profile A14 was obtained.

[0085] Example 15 Aluminum alloy profiles were prepared according to the preparation method of Example 1, except that the casting plate tail temperature was 685 ℃. The upper section of the crystallizer is a strong cooling zone with a length l1 of 150 mm, and the cooling water volume accounts for 50% of the total cooling water volume. The middle section of the crystallizer is a slow cooling zone with a length l2 of 200 mm, and the cooling water volume accounts for 40% of the total cooling water volume. The lower section of the crystallizer is a heat preservation zone with a length l3 of 100 mm, and the cooling water volume accounts for 10% of the total cooling water volume. t1 is 20% of the total solidification time, t2 is 50% of the total solidification time, and t3 is 30% of the total solidification time.

[0086] Aluminum alloy profile A15 was obtained.

[0087] Example 16 Aluminum alloy profiles were prepared according to the preparation method of Example 1, except that R was 99 mm and n was 2.2.

[0088] A16 aluminum alloy profile was obtained.

[0089] Example 17 Aluminum alloy profiles were prepared according to the preparation method of Example 1, except that R was 111 mm and n was 1.8.

[0090] Aluminum alloy profile A17 was obtained.

[0091] Example 18 Aluminum alloy profiles were prepared according to the preparation method of Example 1, except that T was 20 min and y was 5.2.

[0092] A18 aluminum alloy profile was obtained.

[0093] Example 19 Aluminum alloy profiles were prepared according to the preparation method of Example 1, except that T was 40 min and y was 5.7.

[0094] Aluminum alloy profile A19 was obtained.

[0095] Example 20 Aluminum alloy profiles were prepared according to the preparation method of Example 1, except that the annealing regime was 240℃ / 20min×280℃ / 50min×340℃ / 40min.

[0096] Aluminum alloy profile A20 was obtained.

[0097] Example 21 Aluminum alloy profiles were prepared according to the preparation method of Example 1, except that the annealing regime was 260℃ / 40min×320℃ / 60min×360℃ / 60min.

[0098] Aluminum alloy profile A21 was obtained.

[0099] Comparative Example 1 Aluminum alloy profiles were prepared according to the preparation method of Example 1, except that Mg 4.6%, Mn 0.6%, Fe 0.25%, Mg / Mn / Fe ratio 4.6 / 0.6 / 0.25, Mg / Mn=7.67:1, and Mg / Fe=18.4:1.

[0100] Aluminum alloy profile DA1 was obtained.

[0101] Comparative Example 2 Aluminum alloy profiles were prepared according to the preparation method of Example 1, except that Mg 5.0%, Mn 1.0%, Fe 0.25%, Mg / Mn / Fe ratio 5.0 / 1.0 / 0.25, Mg / Mn=5.0:1, and Mg / Fe=20.0:1.

[0102] The extrusion speed is 1.2 m / min.

[0103] Aluminum alloy profile DA2 was obtained.

[0104] Comparative Example 3 Aluminum alloy profiles were prepared according to the preparation method of Example 1, except that the B content was 0.0024%, the Ti content was 0.012%, the Ti / B ratio was 5.0:1, and the Zr / B ratio was 42:1.

[0105] Aluminum alloy profile DA3 was obtained.

[0106] Comparative Example 4 Aluminum alloy profiles were prepared according to the preparation method of Example 1, except that the B content was 0.0020%, the Ti content was 0.12%, the Ti / B ratio was 6.0:1, and the Zr / B ratio was 50:1.

[0107] Aluminum alloy profile DA4 was obtained.

[0108] Comparative Example 5 Aluminum alloy profiles were prepared according to the preparation method of Example 1, except that the Zr content was 0% and Zr / B = 0.

[0109] Aluminum alloy profile DA5 was obtained.

[0110] Comparative Example 6 Aluminum alloy profiles were prepared according to the preparation method of Example 1, except that the Zr content was 0.02% and the Zr / B ratio was 9:1.

[0111] Aluminum alloy profile DA6 was obtained.

[0112] Comparative Example 7 Aluminum alloy profiles were prepared according to the preparation method of Example 1, except that the Zr content was 0.15% and the Zr / B ratio was 68:1.

[0113] Aluminum alloy profile DA7 was obtained.

[0114] Comparative Example 8 Aluminum alloy profiles were prepared according to the preparation method of Example 1, except that the casting rods were homogenized by a 500℃×24h process.

[0115] Aluminum alloy profile DA8 was obtained.

[0116] Comparative Example 9 Aluminum alloy profiles were prepared according to the preparation method of Example 1, except that the annealing temperature was 350°C and held for 120 minutes.

[0117] Aluminum alloy profile DA9 was obtained.

[0118] Comparative Example 10 Aluminum alloy profiles were prepared according to the preparation method of Example 1, except that the casting plate tail temperature was 465 ℃. The upper section of the crystallizer is a strong cooling zone with a length l1 of 80 mm, and the cooling water volume accounts for 30% of the total cooling water volume. The middle section of the crystallizer is a slow cooling zone with a length l2 of 130 mm, and the cooling water volume accounts for 20% of the total cooling water volume. The lower section of the crystallizer is a heat preservation zone with a length l3 of 40mm, and the cooling water volume accounts for 10% of the total cooling water volume. t1 is 30% of the total solidification time, t2 is 40% of the total solidification time, and t3 is 30% of the total solidification time.

[0119] Aluminum alloy profile DA10 was obtained.

[0120] Comparative Example 11 Aluminum alloy profiles were prepared according to the preparation method of Example 1, except that the casting plate tail temperature was 495°C. The upper section of the crystallizer is a strong cooling zone with a length l1 of 160 mm, and the cooling water volume accounts for 60% of the total cooling water volume. The middle section of the crystallizer is a slow cooling zone with a length l2 of 210 mm, and the cooling water volume accounts for 50% of the total cooling water volume. The lower section of the crystallizer is a heat preservation zone with a length l3 of 110 mm, and the cooling water volume accounts for 40% of the total cooling water volume. t1 is 30% of the total solidification time, t2 is 50% of the total solidification time, and t3 is 20% of the total solidification time.

[0121] Aluminum alloy profile DA11 was obtained.

[0122] Comparative Example 12 Aluminum alloy profiles were prepared according to the preparation method of Example 1, except that the annealing regime was 230℃ / 15min × 270℃ / 45min × 330℃ / 35min.

[0123] Aluminum alloy profile DA12 was obtained.

[0124] Comparative Example 13 Aluminum alloy profiles were prepared according to the preparation method of Example 1, except that the annealing regime was 270℃ / 45min×330℃ / 65min×370℃ / 65min.

[0125] Aluminum alloy profile DA13 was obtained.

[0126] Performance tests were performed on A1-A21 and DA1-DA13, as shown in Table 1. Table 1 By comparing the examples and the comparative examples, it can be seen that the comprehensive performance test results of Examples 1-9 and Comparative Examples 1-2 after annealing show that the comprehensive performance is the best when the Mg / Mn ratio is 5.22-6.86:1 and the Mg / Fe ratio is 18.8-19.6:1, with a maximum improvement of about 15%.

[0127] The main advantage is that when the Mg / Mn ratio is between 5.22 and 7.0, the solid solution strengthening of Mg and the second-phase strengthening of Mn reach equilibrium, preventing Mg from forming a large amount of brittle phase with Fe and thus avoiding strength degradation. If the Mg / Mn ratio is < 5.22 (excess Mn), the Al6Mn phase tends to aggregate and grow, weakening the second-phase strengthening effect, increasing dislocation movement resistance, raising extrusion load, and exacerbating die wear. If the ratio is > 7.0 (excess Mg), the number of grain boundary precipitates increases, leading to a decrease in strength. Without sufficient Al6Mn phase pinning at the grain boundaries, grains are prone to abnormal growth during extrusion, resulting in uneven deformation. When the Fe content is fixed at 0.25%, Mn can compete with Fe to form a composite phase, preferentially forming granular α-Al(Fe,Mn)Si phase (lower hardness, rounded shape) with Mn and Si, rather than acicular β-Al5FeSi phase (sharp edges easily cause cracks).

[0128] The results of Examples 1, 10, and 11, and Comparative Examples 3 and 4, show that adding Al-5Ti-B (1% B) and Al-3Ti-0.5B (0.5% B) master alloys to aluminum alloys to control the B content has significant advantages in corrosion resistance and strength compared to adding a single alloy. When added in combination, by controlling the Ti / B atomic ratio to 5.2:1-5.7:1, nano-sized TiB2 composite particles can be formed, uniformly distributed at grain boundaries and within grains. These particles act as a physical barrier, effectively preventing corrosive media such as Cl- from penetrating to grain boundaries and reducing the tendency for intergranular corrosion. When traditional single Al-5Ti-B or Al-3Ti-0.5B (Ti / B = 5:1, 6:1) is added, as in Comparative Examples 3 and 4, the grain size is approximately 45 mm. m, 50 m, pitting depth is 127.01 m. m, 140.87 m; while mixed addition, such as in Example 5, refines the grain size to 20. m, corrosion depth reduced to 83.86 m, strength increased to 340MPa.

[0129] The results of Examples 1, 10, and 11, and Comparative Examples 3 and 4, show that adding Al-5Ti-B (1% B) and Al-3Ti-0.5B (0.5% B) master alloys to aluminum alloys to control the B content has significant advantages in corrosion resistance and strength compared to adding a single alloy. When added in combination, by controlling the Ti / B atomic ratio to 5.2:1-5.7:1, nano-sized TiB2 composite particles can be formed, uniformly distributed at grain boundaries and within grains. These particles act as a physical barrier, effectively preventing corrosive media such as Cl- from penetrating to the grain boundaries and reducing the tendency for intergranular corrosion. When traditional single Al-5Ti-B or Al-3Ti-0.5B (Ti / B = 5:1, 6:1) is added, as in Comparative Examples 3 and 4, the grain size is approximately 45 mm. m, 50 m, pitting depth is 127.01 m. m, 140.87 m; while mixed addition, as in Example 1, refines the grain size to 20. m, corrosion depth reduced to 83.86 m, strength increased to 340MPa.

[0130] The results of Examples 1, 12, and 13, and Comparative Examples 5, 6, and 7 show that when the Zr / B ratio is 9:1 (i.e., the Zr content is low), Al3Zr particles tend to accumulate locally rather than disperse uniformly, forming microscopic electrical couples (Al3Zr / matrix), which promote pitting corrosion initiation. When the Zr / B ratio is 68:1 (i.e., excess Zr), the Al3Zr phase coarsens or agglomerates, potentially becoming the initiation point for localized corrosion. Excess Zr also consumes more B, forming ZrB2 particles instead of (Ti,Zr)B2 composite particles. The nucleation efficiency of ZrB2 is lower than that of (Ti,Zr)B2, resulting in a weakened grain refinement effect, an increased proportion of columnar crystals, and a decrease in strength and plasticity. With a Zr / B ratio of 22:1-55:1, meaning a Zr content between 0.05 and 0.12%, Al3Zr nanoparticles (L12-type structure) formed by an appropriate amount of Zr are uniformly distributed in the grain boundaries and matrix, effectively pinning the grain boundaries, hindering the continuous precipitation of the β phase, and improving corrosion resistance. Zr forms (Ti,Zr)B2 composite particles with Ti and B, exhibiting higher nucleation efficiency than TiB2 alone, resulting in a more significant grain refinement effect, promoting equiaxed crystal formation, and enhancing strength and plasticity.

[0131] The results of Example 1 and Comparative Example 8 show that single-stage homogenization annealing results in low strength and a significant tendency for intergranular corrosion. This may be due to the rapid diffusion of alloying elements such as Mg and Mn in the supersaturated solid solution, leading to coarsening of precipitates (such as Mg2Al3 and Al6(Mn,Fe)) and the potential formation of continuous or coarse aggregates at grain boundaries. These aggregates cannot be uniformly dispersed and strengthened through subsequent aging, resulting in weak strengthening effects. The compositional differences between grain boundaries and the interior grains cause corrosive media to preferentially penetrate along the grain boundaries, leading to intergranular corrosion. Segmented homogenization, forming a uniform solid solution and fine, dispersed second phases (Mg2Al3 and Al6Mn), achieves the best strengthening effect. Compositional homogenization eliminates the micro-cell effect, and the dispersed distribution of precipitates reduces the tendency for grain boundary corrosion.

[0132] The results of Example 1 and Comparative Example 9 show that multi-stage annealing: after furnace cooling to 150°C and then air cooling, the slow cooling stage can gradually release internal stress, avoiding the generation of new thermal stress due to rapid cooling. The material's plasticity is improved and its performance is uniform, making it especially suitable for complex cross-section profiles (such as irregular aluminum profiles), reducing deformation or cracking in subsequent processing (such as cutting and bending). Single-stage annealing: if the cooling rate is not well controlled, the internal stress is not completely eliminated, and the profile is prone to warping and dimensional instability.

[0133] The profiles provided by this invention, through optimized alloy ratios, produce profiles that combine strength and corrosion resistance. Furthermore, the innovative methods of optimizing the preparation process, employing gradient cooling crystallizers, homogenization processes, and annealing processes, yield marine aluminum alloy profiles that combine high strength and high corrosion resistance, meeting the development needs of the shipbuilding industry.

[0134] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A high-strength, corrosion-resistant marine aluminum alloy profile, characterized in that, The components and their weight percentages in the profile are as follows: The Si content is 0.16-0.20%; The Fe content is 0.24-0.26%; The Cu content is 0.05-0.15%; The Mn content is 0.6-0.8%; The Mg content is 4.7-4.9%; The Cr content is 0.05-0.25%; The Zn content is 0.15-0.25%; The Zr content is 0.05-0.12%; The Ti content is 0.01-0.012%; The content of B is 0.001-0.0025%; The content of other impurity elements is ≤0.05%; The total content of other impurity elements is ≤0.15%; The balance is Al; The weight percentage ratio of Ti to B is 5.2-5.7:1, and the weight percentage ratio of Zr to B is 22-55:

1. The weight percentage ratio of Mg, Mn, and Fe is 1:(0.12-0.19):(0.05-0.06); The method for preparing the high-strength, corrosion-resistant marine aluminum alloy profile includes: Smelting, casting, homogenization, extrusion, annealing; The casting conditions include: the temperature at the tail of the casting pan is 675-685 ℃, and a gradient cooling crystallizer is used, which includes an upper section, a middle section and a lower section of the crystallizer. A scraper is used to prevent the cooling water in the upper section of the crystallizer from flowing through the middle and lower sections of the crystallizer, and the cooling water in the middle section of the crystallizer from flowing through the lower section of the crystallizer. The upper section of the crystallizer is a strong cooling zone with a length l1 of 100-150 mm, and the cooling water volume accounts for 40-50% of the total cooling water volume. The middle section of the crystallizer is a slow cooling zone with a length l2 of 150-200 mm, and the cooling water volume accounts for 30-40% of the total cooling water volume. The lower section of the crystallizer is a heat preservation zone with a length l3 of 50-100 mm, and the cooling water volume accounts for 20-30% of the total cooling water volume. The velocity of the melt within the crystallizer, ʋ, and the residence time of the melt within the crystallizer, t. i The relationship is: l i =ʋ×t i Where i = 1, 2, 3, and t is the residence time t in the crystallizer. i The unit is s, t1 is the residence time of the melt in the upper section of the crystallizer, which is 20-30% of the total solidification time, t2 is the residence time of the melt in the middle section of the crystallizer, which is 40-50% of the total solidification time, t3 is the residence time of the melt in the lower section of the crystallizer, which is 20-30% of the total solidification time, and the unit of the melt movement speed ʋ in the crystallizer is mm / s; The homogenization treatment conditions include: the homogenization treatment regime is (500-510℃) × (8-12h) + (400-450℃) × (10-16h); The annealing conditions include: an annealing regime of (240-260)℃×(20-40min)+(280-320)℃×(50-60min)+(340-360)℃×(40-60min), followed by furnace cooling to 140-160℃ and then air cooling to 20-30℃.

2. A method for preparing the high-strength corrosion-resistant marine aluminum alloy profile as described in claim 1, characterized in that, The method includes: Smelting, casting, homogenization, extrusion, annealing; The casting conditions include: the temperature at the tail of the casting pan is 675-685 ℃, and a gradient cooling crystallizer is used, which includes an upper section, a middle section and a lower section of the crystallizer. A scraper is used to prevent the cooling water in the upper section of the crystallizer from flowing through the middle and lower sections of the crystallizer, and the cooling water in the middle section of the crystallizer from flowing through the lower section of the crystallizer. The upper section of the crystallizer is a strong cooling zone with a length l1 of 100-150 mm, and the cooling water volume accounts for 40-50% of the total cooling water volume. The middle section of the crystallizer is a slow cooling zone with a length l2 of 150-200 mm, and the cooling water volume accounts for 30-40% of the total cooling water volume. The lower section of the crystallizer is a heat preservation zone with a length l3 of 50-100 mm, and the cooling water volume accounts for 20-30% of the total cooling water volume. The velocity of the melt within the crystallizer, ʋ, and the residence time of the melt within the crystallizer, t. i The relationship is: l i =ʋ×t i Where i = 1, 2, 3, and t is the residence time t in the crystallizer. i The unit is seconds (s). t1 is the residence time of the melt in the upper section of the crystallizer, which is 20-30% of the total solidification time. t2 is the residence time of the melt in the middle section of the crystallizer, which is 40-50% of the total solidification time. t3 is the residence time of the melt in the lower section of the crystallizer, which is 20-30% of the total solidification time. The unit of the melt's movement speed ʋ in the crystallizer is mm / s.

3. The preparation method according to claim 2, characterized in that, The relationship between the length l2 of the middle section of the crystallizer and the radius R of the casting rod is l2 = (0.8R - 10) × n, where R is 99-111 mm and n is 1.8-2.

2.

4. The preparation method according to claim 2, characterized in that, The smelting conditions include the following relationship: the feeding rate a1 of the intermediate alloy Al-5Ti-B and the feeding rate a2 of the intermediate alloy Al-3Ti-0.5B are as follows: =y, where y is the weight percentage ratio of Ti to B in the high-strength corrosion-resistant marine aluminum alloy profile, which is 5.2-5.7:1; The casting release time is 20-40 minutes.

5. The preparation method according to claim 2, characterized in that, The smelting conditions also include: preheating the raw materials and intermediate alloys at 150-200℃, smelting furnace temperature at 850-950℃, online refining, online degassing, and online filtration of the melt, followed by electromagnetic stirring, slag removal, standing for 30-45 minutes, and semi-continuous casting at an aluminum melt temperature of 715-740℃.

6. The preparation method according to claim 2, characterized in that, The extrusion conditions include: the mold heating temperature is 450-480℃, the homogenized casting rod is heated to 420-460℃ and extruded, the extrusion speed is 0.5-1.5m / min, and the quenching method is water mist.

Images