Aluminum alloy core layer material and strip suitable for radiator hourglass pipe, and preparation method and application of aluminum alloy core layer material and strip

Abstract

The invention belongs to the technical field of aluminum alloy materials, and particularly relates to an aluminum alloy core layer material suitable for a radiator hourglass pipe, a strip, a preparation method and application. The aluminum alloy core layer material comprises, by mass, 0.20% < = Si < = 0.40%, 0.40% < = Fe, 0.20% < = Cu < = 0.70%, 1.10% < = Mn < = 1.80%, 0.03% < = Mg, 0.05% < = Zr < = 0.20%, unavoidable impurities and the balance Al. Wherein the mass ratio of Si to Fe is (0.5-2): 1. According to the aluminum alloy core layer material, through Zr element microalloying and Si / Fe proportion control, crystal grains are fine and uniform, the ductility is larger than or equal to 10%, and the complex forming requirement for punching grooves and protruding points of the hourglass pipe can be met; in addition, excellent tensile strength, yield strength and corrosion resistance are achieved, and the mechanical requirement and the corrosion resistance requirement of the hourglass pipe are met.

Description

Technical Field

[0001] This invention belongs to the field of aluminum alloy material technology, specifically relating to an aluminum alloy core layer material, strip, preparation method, and application suitable for radiator hourglass tubes. Background Technology

[0002] The hourglass tube in agricultural machinery radiators (such as tractors, harvesters, rice transplanters, etc.) is a core component ensuring efficient heat dissipation. It is typically manufactured using composite strip material made of 3XXX series aluminum alloy (such as 3003 alloy) as the core layer and 4XXX series aluminum alloy (such as 4343 alloy) as the brazing layer. The typical composition of existing core layer materials includes Si≤0.60%, Fe≤0.70%, 0.05%≤Cu≤0.20%, 1.0%≤Mn≤1.50%, and the balance Al. The preparation process requires steps such as melting and casting, high-temperature homogenization (580℃-620℃, holding for 8h-16h), hot rolling composite, multi-pass cold rolling, and recrystallization annealing (300℃-350℃, holding for 0.5h-2h). Among these, homogenization is considered a necessary prerequisite for ensuring the plasticity and formability of the material—by precipitating AlMn phases to pin grain boundaries, the recrystallized grains are refined to improve plasticity.

[0003] However, agricultural machinery often operates under extreme conditions such as high dust, straw clippings, and severe vibration, and existing materials and processes have significant shortcomings: First, it is difficult to balance formability and strength, sacrificing plasticity in pursuit of strength, which makes hourglass tubes prone to cracking when punching grooves and protrusions; second, the homogenization process is costly, and prolonged high-temperature heat preservation significantly increases energy consumption and production cycle; third, insufficient mechanical properties make it difficult to withstand impacts from sand and gravel collisions and repeated vibrations, reducing the reliability of the radiator; fourth, weak corrosion resistance, prolonged contact with the cooling medium easily leads to pitting or intergranular corrosion, causing pipe leaks. These defects severely restrict the service life and operational stability of agricultural machinery radiators.

[0004] To address the aforementioned problems with existing technologies, there is an urgent need to develop a new type of aluminum alloy core material and preparation process to simultaneously meet the requirements of complex hourglass tube forming (elongation ≥10%), high strength, excellent corrosion resistance, and simplified production process. Summary of the Invention

[0005] Based on this, the present invention solves the pain points of existing materials such as poor formability, insufficient strength, weak corrosion resistance and complex process by micro-alloying of Zr element and controlling Si / Fe ratio, combined with process improvement, and provides a high-performance and low-cost technical solution for hourglass tubes of agricultural machinery.

[0006] To achieve the above objectives, the present invention can adopt the following technical solutions: This invention provides an aluminum alloy core material suitable for radiator hourglass tubes. The aluminum alloy core material, by mass fraction, includes 0.20%≤Si≤0.40%, Fe≤0.40%, 0.20%≤Cu≤0.70%, 1.10%≤Mn≤1.80%, Mg≤0.03%, 0.05%≤Zr≤0.20%, as well as unavoidable impurities and residual Al. The percentage of a single impurity is ≤0.05%, and the total amount of impurities is ≤0.15%. The mass ratio of Si to Fe is (0.5-2):1.

[0007] Preferably, the aluminum alloy core material is selected from any one of the following: (i) The aluminum alloy core material, by mass fraction, includes 0.20% Si, 0.20% Fe, 0.70% Cu, 1.50% Mn, 0.03% Mg, 0.08% Zr, as well as unavoidable impurities and residual Al, with the percentage of a single impurity ≤0.05% and the total amount of impurities ≤0.15%; (ii) The aluminum alloy core material, by mass fraction, includes Si 0.25%, Fe 0.40%, Cu 0.50%, Mn 1.50%, Mg 0.03%, Zr 0.10%, as well as unavoidable impurities and residual Al, with the percentage of a single impurity ≤0.05% and the total amount of impurities ≤0.15%; (iii) The aluminum alloy core material, by mass fraction, includes Si 0.40%, Fe 0.20%, Cu 0.50%, Mn 1.55%, Mg 0.03%, Zr 0.15%, as well as unavoidable impurities and residual Al, with the percentage of a single impurity ≤0.05% and the total amount of impurities ≤0.15%; (iv) The aluminum alloy core material, by mass fraction, includes 0.35% Si, 0.35% Fe, 0.65% Cu, 1.45% Mn, 0.03% Mg, 0.20% Zr, as well as unavoidable impurities and residual Al, with the percentage of a single impurity ≤0.05% and the total amount of impurities ≤0.15%; (v) The aluminum alloy core material, by mass fraction, includes 0.20% Si, 0.40% Fe, 0.50% Cu, 1.50% Mn, 0.03% Mg, 0.08% Zr, as well as unavoidable impurities and residual Al, with the percentage of a single impurity ≤0.05% and the total amount of impurities ≤0.15%; (vi) The aluminum alloy core material, by mass fraction, includes 0.20% Si, 0.20% Fe, 0.50% Cu, 1.50% Mn, 0.03% Mg, 0.05% Zr, as well as unavoidable impurities and residual Al, with the percentage of a single impurity ≤0.05% and the total amount of impurities ≤0.15%.

[0008] Another aspect of the present invention provides an aluminum alloy strip suitable for a radiator hourglass tube, comprising a first brazing layer, a core layer, and a second brazing layer, wherein the core layer is made of the aforementioned aluminum alloy core layer material.

[0009] Preferably, in the above-mentioned aluminum alloy strip, both the first brazing layer and the second brazing layer are 4343 aluminum alloy.

[0010] Preferably, in the above-mentioned aluminum alloy strip, the coverage rates of the first brazing layer and the second brazing layer are 4%-6% and 8%-12% on one side, respectively.

[0011] In another aspect, the present invention provides a method for preparing the above-mentioned aluminum alloy strip, the method comprising: (1) preparing an aluminum alloy core layer material into a core layer ingot; (2) stacking the first brazing layer ingot, the core layer ingot and the second brazing layer ingot in the order of top, middle and bottom to form a composite ingot; (3) subjecting the composite ingot to hot rolling, cold rolling and H24 annealing in sequence to obtain aluminum alloy strip.

[0012] Preferably, the above preparation method satisfies one or more of the following conditions: (a) the thickness of the composite ingot is 460mm-530mm; (b) the initial rolling temperature of hot rolling is 450℃-530℃, the deformation per pass is 30%-50%, and the final rolling thickness is 4.0mm-6.0mm; (c) the reduction per pass of cold rolling is 30%-50%; (d) H24 annealing includes: annealing temperature of 300℃-350℃ and time of 0.5h-2.5h.

[0013] More preferably, in the above preparation method, the thickness after cold rolling is 0.25mm-0.35mm.

[0014] Preferably, in the above preparation method, the method of preparing the aluminum alloy core material into a core ingot includes: (1) melting the aluminum alloy core material to obtain an aluminum alloy liquid, with a melting temperature of 710℃-760℃; (2) refining, settling, filtering, and casting the aluminum alloy liquid in sequence to obtain an initial core ingot, with a casting temperature of 700℃-740℃; (3) sawing and milling the initial aluminum alloy core ingot to obtain a core ingot.

[0015] In another aspect, the present invention provides a radiator hourglass tube, which is made from the aluminum alloy strip described above or the aluminum alloy strip prepared by the above preparation method.

[0016] The beneficial effects of this invention include at least the following: The aluminum alloy core material for radiator hourglass tubes provided by this invention, through Zr element micro-alloying and control of the Si / Fe ratio, has fine and uniform grains and an elongation of ≥10%, which can meet the complex forming requirements of hourglass tubes for punching grooves and protrusions; and in the H24 state, the tensile strength is >210MPa and the yield strength is ≥170MPa, which is sufficient to withstand the impact and vibration in agricultural machinery operations; in addition, the aluminum alloy strip prepared from the aluminum alloy core material of this invention can still maintain its integrity after passing through OY solution for 7 cycles, and shows no leakage after being pressure tested at 0.125MPa for 60s, exhibiting excellent corrosion resistance and meeting the stringent requirements for corrosion resistance inside hourglass tubes. Detailed Implementation

[0017] The embodiments described are provided to better illustrate the present invention, but are not intended to limit the scope of the invention to the embodiments described. Therefore, non-essential improvements and adjustments made to the embodiments by those skilled in the art based on the above description are still within the scope of protection of the present invention.

[0018] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit this disclosure. Singular expressions include plural expressions unless they have a distinct meaning in the context. As used herein, it should be understood that terms such as “comprising,” “having,” “including,” are intended to indicate the presence of features, numbers, operations, components, parts, elements, materials, or combinations thereof. The terminology of the invention is disclosed in the specification and is not intended to exclude the possibility that one or more other features, numbers, operations, components, parts, elements, materials, or combinations thereof may be present or added. As used herein, “ / ” may be interpreted as “and” or “or,” depending on the context.

[0019] In a first aspect, embodiments of the present invention provide an aluminum alloy core layer material suitable for a radiator hourglass tube. The aluminum alloy core layer material, by mass fraction, includes 0.20%≤Si≤0.40%, Fe≤0.40%, 0.20%≤Cu≤0.70%, 1.10%≤Mn≤1.80%, Mg≤0.03%, 0.05%≤Zr≤0.20%, as well as unavoidable impurities and residual Al. The percentage of a single impurity is ≤0.05%, and the total amount of impurities is ≤0.15%. The mass ratio of Si to Fe is (0.5-2):1.

[0020] It should be noted that the design principle of the aluminum alloy core material in this invention is as follows: The addition of Zr can form dispersed Al3Zr particles, which can effectively inhibit recrystallization and recrystallized grain growth during annealing. Even without homogenization treatment of the core layer, a fine and uniform grain structure can be obtained, thereby giving the strip excellent strength and plasticity; the mass ratio of Si to Fe is controlled at (0.5-2):1 to refine the size of the second phase and improve the uniformity of distribution, thereby ensuring the strength, plasticity and corrosion resistance of the strip; since when the mass ratio of Si to Fe is <0.5, more large-sized Al(Mn,Fe) phases and Al2O3 phases will be generated. 12 (Mn,Fe)3Si phase; when the mass ratio of Si to Fe is greater than 2, a large number of large-sized needle-like Al atoms will be generated. 12 (Mn,Fe)3Si phase; while Al formed when the mass ratio of Si to Fe satisfies 0.5≤Si / Fe≤2. 12 The (Mn,Fe)3Si phase is small in size and uniformly distributed; specifically, Al(Mn,Fe) phase and Al... 12 The (Mn,Fe)3Si phase requires the consumption of Mn in the matrix, which reduces the formation of small-sized AlMn phases during homogenization. These small-sized AlMn phases can hinder recrystallization grain growth during subsequent annealing and recrystallization. Therefore, controlling the Al(Mn,Fe) phase and Al... 12 The formation of the (Mn,Fe)3Si phase helps refine the recrystallized grain size. Simultaneously, optimized heat treatment processes (including homogenization and annealing after cold rolling) work together to refine the grain structure, reducing the risk of cracking in subsequent stamping and bending processes, and improving the processing yield and shape adaptability of the hourglass tubes for agricultural machinery radiators. Furthermore, the coarse Al(Mn,Fe) phase and Al... 12 The (Mn,Fe)3Si phase can promote pitting corrosion in the strip, leading to perforation and leakage in the hourglass tube, causing the radiator to fail. Therefore, the mass ratio of Si to Fe in this invention is (0.5-2):1. This ensures that the tensile strength of the material can reach 190MPa, the yield strength cannot reach 170MPa, and the elongation can still reach more than 10%, achieving a synergistic improvement in high strength and good plasticity. It also improves the corrosion resistance of the composite strip, while enhancing the formability of the material and the reliability of the radiator.

[0021] In some specific examples, the aluminum alloy core material is selected from any of the following: (i) The aluminum alloy core material, by mass fraction, includes 0.20% Si, 0.20% Fe, 0.70% Cu, 1.50% Mn, 0.03% Mg, 0.08% Zr, as well as unavoidable impurities and residual Al, with the percentage of a single impurity ≤0.05% and the total amount of impurities ≤0.15%; (ii) The aluminum alloy core material, by mass fraction, includes Si 0.25%, Fe 0.40%, Cu 0.50%, Mn 1.50%, Mg 0.03%, Zr 0.10%, as well as unavoidable impurities and residual Al, with the percentage of a single impurity ≤0.05% and the total amount of impurities ≤0.15%; (iii) The aluminum alloy core material, by mass fraction, includes Si 0.40%, Fe 0.20%, Cu 0.50%, Mn 1.55%, Mg 0.03%, Zr 0.15%, as well as unavoidable impurities and residual Al, with the percentage of a single impurity ≤0.05% and the total amount of impurities ≤0.15%; (iv) The aluminum alloy core material, by mass fraction, includes 0.35% Si, 0.35% Fe, 0.65% Cu, 1.45% Mn, 0.03% Mg, 0.20% Zr, as well as unavoidable impurities and residual Al, with the percentage of a single impurity ≤0.05% and the total amount of impurities ≤0.15%; (v) The aluminum alloy core material, by mass fraction, includes 0.20% Si, 0.40% Fe, 0.50% Cu, 1.50% Mn, 0.03% Mg, 0.08% Zr, as well as unavoidable impurities and residual Al, with the percentage of a single impurity ≤0.05% and the total amount of impurities ≤0.15%; (vi) The aluminum alloy core material, by mass fraction, includes 0.20% Si, 0.20% Fe, 0.50% Cu, 1.50% Mn, 0.03% Mg, 0.05% Zr, as well as unavoidable impurities and residual Al, with the percentage of a single impurity ≤0.05% and the total amount of impurities ≤0.15%.

[0022] It should be noted that the aluminum alloy core material in this invention can preferably be the aluminum alloy core material with the mass fraction mentioned above. The yield strength of the aluminum alloy core material can be ≥174MPa, the tensile strength can be ≥217MPa, and the elongation can be ≥10.6%.

[0023] Secondly, embodiments of the present invention provide an aluminum alloy strip suitable for a radiator hourglass tube, comprising a first brazing layer, a core layer, and a second brazing layer, wherein the core layer is made of the aforementioned aluminum alloy core layer material.

[0024] It should be noted that the core layer made of the aluminum alloy core layer material in this invention can be used together with the first brazing layer and the second brazing layer to prepare aluminum alloy strip.

[0025] In some specific examples, the first brazing layer and the second brazing layer in the above-mentioned aluminum alloy strip are both made of 4343 aluminum alloy.

[0026] It should be noted that the first brazing layer and the second brazing layer in this invention are known in the art, including but not limited to 4343 aluminum alloy.

[0027] In some specific examples, in the aforementioned aluminum alloy strip, the coverage rates of the first brazing layer and the second brazing layer are 4%-6% and 8%-12% on one side, respectively.

[0028] It should be noted that the coverage rates of the first brazing layer and the second brazing layer in this invention are 4%-6% (e.g., 4.5%, 5% or 5.5%) and 8%-12% (e.g., 9%, 10% or 11%) on one side, respectively.

[0029] Thirdly, the present invention provides a method for preparing the above-mentioned aluminum alloy strip, the method comprising: (1) preparing an aluminum alloy core layer material into a core layer ingot; (2) stacking the first brazing layer ingot, the core layer ingot and the second brazing layer ingot in the order of top, middle and bottom to form a composite ingot; (3) subjecting the composite ingot to hot rolling, cold rolling and H24 annealing in sequence to obtain aluminum alloy strip.

[0030] It should be noted that the preparation method of the aluminum alloy strip in this invention is known in the art, and it can preferably be prepared according to the preparation method listed above. The aluminum alloy strip obtained after annealing in the H24 state is in the H24 state, which ensures both sufficient strength and excellent stamping formability.

[0031] In some specific examples, the above preparation method satisfies one or more combinations of the following conditions: (a) The thickness of the composite ingot is 460mm-530mm, such as 470mm, 480mm, 490mm, 500mm, 510mm or 520mm, etc.; (b) The initial rolling temperature of hot rolling is 450℃-530℃, the deformation per pass is 30%-50%, and the final rolling thickness is 4.0mm-6.0mm. Specifically, hot rolling under the above-mentioned hot rolling process can enable the first brazing layer and the second brazing layer to achieve the preset coverage rate according to the preset conditions. Among them, the initial rolling temperature can be 450℃-530℃, such as 470℃, 480℃, 490℃, 500℃, 510℃ or 520℃, etc.; the deformation per pass can be 30%-50%, such as 35%, 40% or 45%, etc.; and the final rolling thickness is 4.0mm-6.0mm, such as 4.5mm, 5.0mm or 5.5mm, etc. (c) The single-pass reduction in cold rolling is 30%-50%, such as 35%, 40% or 45%; (d) Annealing in H24 condition includes: annealing temperature of 300℃-350℃ and time of 0.5h-2.5h; specifically, the annealing temperature can be 300℃-350℃, such as 310℃, 320℃, 330℃ or 340℃, etc., and the time can be 0.5h-2.5h, such as 1h, 1.5h or 2h, etc.

[0032] In some specific examples, the thickness after cold rolling in the above preparation method is 0.25mm-0.35mm.

[0033] It should be noted that the thickness after cold rolling in this invention is determined according to the size of the radiator hourglass tube. Based on the size of commonly used radiator hourglass tubes, the thickness after cold rolling can preferably be 0.25mm-0.35mm, such as 0.27mm, 0.3mm or 0.33mm.

[0034] In some specific examples, the method of preparing the aluminum alloy core material into a core ingot in the above preparation method includes: (1) melting the aluminum alloy core material to obtain an aluminum alloy liquid, with a melting temperature of 710℃-760℃; (2) refining, settling, filtering and casting the aluminum alloy liquid in sequence to obtain an initial core ingot, with a casting temperature of 700℃-740℃; (3) sawing and milling the initial aluminum alloy core ingot to obtain a core ingot.

[0035] It should be noted that in the core layer casting method of the present invention, the melting temperature can be 710℃-760℃, such as 720℃, 730℃, 740℃ or 750℃, etc.; the casting temperature can be 700℃-740℃, such as 710℃, 720℃ or 730℃, etc.

[0036] It should be noted that the method for preparing the core layer ingot in this invention is known in the art. The above method is preferred. The above method does not require homogenization treatment, which shortens the production cycle and reduces energy consumption and production costs.

[0037] Fourthly, embodiments of the present invention provide a radiator hourglass tube, which is made from the aluminum alloy strip described above or the aluminum alloy strip prepared by the above-described preparation method.

[0038] It should be noted that the aluminum alloy core material in this invention, through Zr micro-alloying and control of the Si / Fe mass ratio, has fine and uniform grains and an elongation of ≥10%, which can meet the complex forming requirements of hourglass tubes for punching grooves and protrusions. Furthermore, in the H24 state, the tensile strength is >210MPa and the yield strength is ≥170MPa, sufficient to withstand the impact and vibration during agricultural machinery operation. In addition, the optimized composition and stable H24 state microstructure ensure that the strip maintains its integrity after seven cycles of OY solution immersion, and shows no leakage after a 0.125MPa pressure test for 60s, meeting the stringent requirements for corrosion resistance inside hourglass tubes.

[0039] To better understand the present invention, specific examples are provided below to further illustrate the content of the present invention, but the content of the present invention is not limited to the examples below.

[0040] In the following example, the brazing layer of the aluminum alloy strip is made of 4343 aluminum alloy (with the following composition: Fe≤0.8, 6.8≤Si≤8.2, Mn≤0.1, Cu≤0.25, Zn≤0.2, and unavoidable impurities, with a single impurity accounting for ≤0.05%, a total impurity accounting for ≤0.15%, and the balance being Al), double-sided composite, with a coverage rate of 5% and 11% on one side.

[0041] Preparation Examples Example 1 (1) Prepare the core layer composition according to the mass percentages shown in Table 1; Table 1. Mass percentage of core components in Example 1 (2) The core layer components are melted, cast, and processed to obtain the core layer ingot. The specific process is as follows: (2-1) Core layer alloy smelting Weigh pure aluminum ingots, Al-Fe master alloy, Al-Mn master alloy, Al-Cu master alloy, and Al-Zr master alloy according to the mass percentages in Table 1 and put them into the smelting furnace (Mg is considered as an impurity and does not need to be added separately). Smelt at 750℃ to obtain molten aluminum. (2-2) Core layer alloy casting The aluminum liquid obtained in (2-1) was successively refined with Ar gas for 30 min, allowed to stand for 30 min, filtered through a 30+50Ppi double-stage filter, and cast at 740℃ to obtain a core alloy ingot.

[0042] (2-3) Sawing and milling The ingot obtained from process (2-2) is cut off at the head, tail and edge, and the upper and lower surfaces are milled. (3) The brazed layer and the milled core layer ingot are stacked and fixed in order of top, middle and bottom (coverage rate is 5% (24cm for the top layer) and 11% (52.8cm for the bottom layer) on one side), and the total thickness of the ingot is 480mm; the ingot is heated to 480℃ and then hot-rolled to obtain the initial hot-rolled strip; the deformation of a single pass of hot rolling is 30%-50%, and the final rolling thickness is 5.0mm; (4) The hot-rolled initial strip is cold-rolled to obtain a cold-rolled initial strip; wherein the single-pass reduction of the cold rolling is 30%-50%, and the final rolling thickness is 0.25mm; (5) The initial cold-rolled strip is annealed in H24 state to obtain aluminum alloy strip; wherein, the H24 state annealing is carried out at 320℃ for 2 hours and then naturally cooled to obtain the finished composite strip.

[0043] Example 2 (1) Prepare the core layer composition according to the mass percentages shown in Table 2; Table 2. Mass percentage of core layer components in Example 2 (2) Same as step (2) in Example 1; (3) The brazing layer and the core layer ingot are stacked and fixed in order of top, middle and bottom (the coverage rate is 6% and 11% on one side), and the total thickness of the ingot is 490mm; the ingot is heated to 480℃ and then hot-rolled to obtain the initial hot-rolled strip; the deformation of a single pass of hot rolling is 30%-50%, and the final rolling thickness is 5.0mm. (4) The hot-rolled initial strip is cold-rolled to obtain a cold-rolled initial strip; wherein the single-pass reduction of the cold rolling is 30%-50%, and the final rolling thickness is 0.30mm; (5) The initial cold-rolled strip is annealed in H24 state to obtain aluminum alloy strip; wherein, the H24 state annealing is constant at 340℃ for 1 hour, and then naturally cooled to obtain the finished composite strip.

[0044] Example 3 (1) Prepare the core layer composition according to the mass percentages shown in Table 3; Table 3. Mass percentage of core layer components in Example 3 (2) Same as step (2) in Example 1; (3) The brazing layer and the core layer ingot are stacked and fixed in order of top, middle and bottom (the coverage rate is 5% and 9% on one side), and the total thickness of the ingot is 480mm; the ingot is heated to 500℃ and then hot-rolled to obtain the initial hot-rolled strip; the deformation of a single pass of hot rolling is 30%-50%, and the final rolling thickness is 6.0mm. (4) The hot-rolled initial strip is cold-rolled to obtain a cold-rolled initial strip; wherein the single-pass reduction of the cold rolling is 30%-50%, and the final rolling thickness is 0.25mm; (5) The initial cold-rolled strip is annealed in H24 state to obtain aluminum alloy strip; wherein, the H24 state annealing is constant at 340℃ for 1.5h, and then naturally cooled to obtain the finished composite strip.

[0045] Example 4 (1) Prepare the core layer composition according to the mass percentages shown in Table 4; Table 4. Mass percentage of core layer components in Example 4 (2) Same as step (2) in Example 1; (3) The brazing layer and the core layer ingot are stacked and fixed in order of top, middle and bottom (the coverage rate is 6% and 11% on one side), and the total thickness of the ingot is 510mm; the ingot is heated to 500℃ and then hot-rolled to obtain the initial hot-rolled strip; the deformation of a single pass of hot rolling is 30%-50%, and the final rolling thickness is 6.0mm. (4) The hot-rolled initial strip is cold-rolled to obtain a cold-rolled initial strip; wherein the single-pass reduction of the cold rolling is 30%-50%, and the final rolling thickness is 0.35mm; (5) The initial cold-rolled strip is annealed in H24 state to obtain aluminum alloy strip; wherein, the H24 state annealing is constant at 350℃ for 0.5h, and then naturally cooled to obtain the finished composite strip.

[0046] Example 5 Example 5 is largely the same as Example 1, except that the mass percentage of the core layer component is different, while the rest is the same as Example 1; the mass percentage of the core layer component in Example 5 is shown in Table 5 below.

[0047] Table 5. Mass percentage of core layer components in Example 5 Example 6 Example 6 is largely the same as Example 1, except that the mass percentage of the core layer component is different, while the rest is the same as Example 1; the mass percentage of the core layer component in Example 6 is shown in Table 6 below.

[0048] Table 6. Mass percentage of core layer components in Example 6 Comparative Example 1 Comparative Example 1 is largely the same as Example 1, except that the mass percentage of the core layer component is different, while the rest is the same as Example 1; the core layer component of Comparative Example 1 is shown in Table 7 below.

[0049] Table 7. Mass percentage of core components in Comparative Example 1 Comparative Example 2 Comparative Example 2 is largely the same as Example 1, except that the mass percentage of the core layer component is different, while the rest is the same as Example 1; the core layer component of Comparative Example 2 is shown in Table 8 below.

[0050] Table 8. Mass percentage of core components in Comparative Example 2 Comparative Example 3 Comparative Example 3 is largely the same as Example 1, except that the mass percentage of the core layer component is different, while the rest is the same as Example 1; the core layer component of Comparative Example 3 is shown in Table 9 below.

[0051] Table 9. Mass percentage of core components in Comparative Example 3 Comparative Example 4 Comparative Example 4 is largely the same as Example 1, except that the core layer composition is different, while the rest is the same as Example 1; the core layer composition of Comparative Example 4 is shown in Table 10 below.

[0052] Table 10. Mass percentage of core components in Comparative Example 4 Comparative Example 5 (1) Prepare the core layer composition according to the mass percentages shown in Table 11; Table 11. Mass percentage of core components in Comparative Example 5 (2) Same as step (2) in Example 1; (3) The brazing layer and the core layer ingot are stacked and fixed in order of top, middle and bottom (the coverage rate is 5% and 10% on one side), and the total thickness of the ingot is 480mm; the ingot is heated to 500℃ and then hot-rolled to obtain the initial hot-rolled strip; the deformation of a single pass of hot rolling is 30%-50%, and the final rolling thickness is 6.0mm. (4) The hot-rolled initial strip is cold-rolled to obtain a cold-rolled initial strip; wherein the single-pass reduction of the cold rolling is 30%-50%, and the final rolling thickness is 0.35mm; (5) The initial cold-rolled strip is annealed in H24 state to obtain aluminum alloy strip; wherein, the H24 state annealing is constant at 340℃ for 1 hour, and then naturally cooled to obtain the finished composite strip.

[0053] Comparative Example 6 (1) Prepare the core layer composition according to the mass percentages shown in Table 12; Table 12. Mass percentage of core components in Comparative Example 6 (2) The core layer components are melted, cast, processed and homogenized to obtain the core layer ingot; wherein, the homogenization is carried out at 610℃ for 12 hours; (3) The brazing layer and the core layer ingot are stacked and fixed in order of top, middle and bottom (the coverage rate is 5% and 10% on one side), and the total thickness of the ingot is 490mm; the ingot is heated to 500℃ and then hot-rolled to obtain the initial hot-rolled strip; the deformation of a single pass of hot rolling is 30%-50%, and the final rolling thickness is 6.0mm. (4) The hot-rolled initial strip is cold-rolled to obtain a cold-rolled initial strip; wherein the single-pass reduction of the cold rolling is 30%-50%, and the final rolling thickness is 0.35mm; (5) The initial cold-rolled strip is annealed in H24 state to obtain aluminum alloy strip; wherein, H24 state annealing is constant temperature at 330℃ for 1h, and then naturally cooled to obtain finished composite strip.

[0054] Performance testing The yield strength, tensile strength, and elongation of the aluminum alloy strips prepared in the examples and comparative examples were tested according to GB / T 228.1-2021 Metallic Materials—Tensive Testing—Part 1: Test Method at Room Temperature. The corrosion resistance of the aluminum alloy strips prepared in the examples and comparative examples was tested according to sections 5.6 and 5.1 of JB / T 8577-2015 Technical Conditions for Water Radiators of Internal Combustion Engines. The test results are shown in Table 13 below.

[0055] Table 13 Mechanical and corrosion resistance properties of aluminum alloy strips prepared in the examples and comparative examples As shown in Table 13 above, the yield strength and tensile strength of the aluminum alloy strips prepared in Examples 1 to 6 are significantly higher than those in Comparative Examples 1 to 6. Furthermore, the aluminum alloy strips prepared in Examples 1 to 6 maintain their integrity after seven cycles of OY solution immersion and show no leakage after a 0.125 MPa pressure test for 60 s, meeting the stringent requirements for corrosion resistance inside the hourglass tube. In contrast, the aluminum alloy strips prepared in Comparative Examples 1 to 6 exhibited leakage and failed to meet the corrosion resistance requirements inside the hourglass tube. Additionally, although the elongation of the aluminum alloy strips prepared in Comparative Examples 4 and 6 is slightly higher than that in Examples 1 to 6, their yield strength and tensile strength differ significantly. Overall, the mechanical properties of the aluminum alloy strips prepared in Examples 1 to 6 are superior to those prepared in Comparative Examples 1 to 6.

[0056] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. An aluminum alloy core material suitable for radiator hourglass tubes, characterized in that, The aluminum alloy core material, by mass fraction, includes 0.20%≤Si≤0.40%, Fe≤0.40%, 0.20%≤Cu≤0.70%, 1.10%≤Mn≤1.80%, Mg≤0.03%, 0.05%≤Zr≤0.20%, as well as unavoidable impurities and residual Al. The percentage of a single impurity is ≤0.05%, and the total amount of impurities is ≤0.15%. Among them, the mass ratio of Si to Fe is (0.5-2):

1.

2. The aluminum alloy core material according to claim 1, characterized in that, The aluminum alloy core material is selected from any of the following: (i) The aluminum alloy core material, by mass fraction, includes 0.20% Si, 0.20% Fe, 0.70% Cu, 1.50% Mn, 0.03% Mg, 0.08% Zr, as well as unavoidable impurities and residual Al, with the percentage of a single impurity ≤0.05% and the total amount of impurities ≤0.15%; (ii) The aluminum alloy core material, by mass fraction, includes Si 0.25%, Fe 0.40%, Cu 0.50%, Mn 1.50%, Mg 0.03%, Zr 0.10%, as well as unavoidable impurities and residual Al, with the percentage of a single impurity ≤0.05% and the total amount of impurities ≤0.15%; (iii) The aluminum alloy core material, by mass fraction, includes Si 0.40%, Fe 0.20%, Cu 0.50%, Mn 1.55%, Mg 0.03%, Zr 0.15%, as well as unavoidable impurities and residual Al, with the percentage of a single impurity ≤0.05% and the total amount of impurities ≤0.15%; (iv) The aluminum alloy core material, by mass fraction, includes 0.35% Si, 0.35% Fe, 0.65% Cu, 1.45% Mn, 0.03% Mg, 0.20% Zr, as well as unavoidable impurities and residual Al, with the percentage of a single impurity ≤0.05% and the total amount of impurities ≤0.15%; (v) The aluminum alloy core material, by mass fraction, includes Si 0.20%, Fe 0.40%, Cu 0.50%, Mn 1.50%, Mg 0.03%, Zr 0.08%, as well as unavoidable impurities and residual Al, with the percentage of a single impurity ≤0.05% and the total amount of impurities ≤0.15%; (vi) The aluminum alloy core material, by mass fraction, includes 0.20% Si, 0.20% Fe, 0.50% Cu, 1.50% Mn, 0.03% Mg, 0.05% Zr, as well as unavoidable impurities and residual Al, with the percentage of a single impurity ≤0.05% and the total amount of impurities ≤0.15%.

3. An aluminum alloy strip suitable for radiator hourglass tubes, characterized in that, It includes a first brazing layer, a core layer, and a second brazing layer, wherein the core layer is made of the aluminum alloy core layer material as described in claim 1 or 2.

4. The aluminum alloy strip according to claim 3, characterized in that, Both the first and second brazing layers are made of 4343 aluminum alloy.

5. The aluminum alloy strip according to claim 3 or 4, characterized in that, The coverage rates of the first and second brazing layers are 4%-6% and 8%-12% on one side, respectively.

6. The method for preparing the aluminum alloy strip according to any one of claims 3 to 5, characterized in that, Preparation methods include: (1) Prepare the aluminum alloy core material into a core ingot; (2) The first brazing layer ingot, the core layer ingot, and the second brazing layer ingot are stacked in the order of top, middle, and bottom to form a composite ingot; (3) The composite ingot is subjected to hot rolling, cold rolling and H24 annealing in sequence to obtain aluminum alloy strip.

7. The preparation method according to claim 6, characterized in that, The preparation method satisfies one or more of the following conditions: (a) The thickness of the composite ingot is 460mm-530mm; (b) The initial rolling temperature of hot rolling is 450℃-530℃, the deformation per pass is 30%-50%, and the final rolling thickness is 4.0mm-6.0mm; (c) The single-pass reduction in cold rolling is 30%-50%; (d) Annealing in H24 condition includes annealing temperature of 300℃-350℃ and time of 0.5h-2.5h.

8. The preparation method according to claim 7, characterized in that, The thickness after cold rolling is 0.25mm-0.35mm.

9. The preparation method according to any one of claims 6 to 8, characterized in that, Methods for preparing aluminum alloy core material into core ingots include: (1) The aluminum alloy core material is melted to obtain aluminum alloy liquid, and the melting temperature is 710℃-760℃; (2) The aluminum alloy liquid is refined, allowed to stand, filtered and cast in sequence to obtain the initial core layer ingot. The casting temperature is 700℃-740℃. (3) The initial aluminum alloy core layer ingot is sawn and milled to obtain the core layer ingot.

10. A radiator hourglass tube, characterized in that, It is prepared from aluminum alloy strip as described in any one of claims 3 to 5 or aluminum alloy strip prepared by the preparation method described in any one of claims 6 to 9.

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