High-strength corrosion-resistant aluminum alloy composite strip for radiator of engineering machinery and preparation method of high-strength corrosion-resistant aluminum alloy composite strip

Abstract

The invention discloses a high-strength corrosion-resistant aluminum alloy composite strip for an engineering machinery radiator and a preparation method of the high-strength corrosion-resistant aluminum alloy composite strip and belongs to the technical field of material science. The strip comprises a first brazing layer, a core material and a second brazing layer; the first brazing layer and the second brazing layer are both made of 4004 aluminum alloy, and the core material is made of modified 3-series aluminum alloy. The method comprises the following steps: smelting and casting a core material; composite hot rolling; and cold rolling. By optimizing the alloy components, the mechanical property of the aluminum alloy composite belt is greatly improved. The size and the number of a second phase are reduced by controlling the content of Fe and Si, so that the occurrence of spot corrosion is reduced, and uniform corrosion can be promoted by adding the Ti element; meanwhile, through optimization of alloy components, a high-density precipitation zone with the width of 20-60 microns and reduced potential is formed in an interface area of a core material and a brazing layer after the composite strip is brazed, and the protection effect of a sacrificial anode is achieved; the aluminum alloy composite strip not only has high strength, but also has excellent corrosion resistance, and a foundation is provided for the development of light weight of materials.

Description

Technical Field

[0001] This invention belongs to the field of materials science and technology, specifically relating to a high-strength corrosion-resistant aluminum alloy composite strip for radiators of engineering machinery and its preparation method. Background Technology

[0002] With the deepening of global carbon peaking and carbon neutrality strategies, the demand for lightweight and highly reliable radiators in the construction machinery sector continues to rise. Brazed aluminum plate-fin radiators, due to their compact structure and high heat transfer efficiency, have become a core component of thermal management systems for construction machinery. The performance of their key material, aluminum alloy composite strip, directly determines the reliability and service life of the components.

[0003] Traditional 4004 / 3003 / 4004 composite tapes have long dominated the market due to their mature manufacturing process. However, their brazed strength is relatively low, and they are prone to pitting corrosion leading to perforation and leakage in actual use environments. As engineering machinery radiators trend towards thinner profiles, higher corrosion resistance, and longer lifespans, their inherent defects are becoming increasingly apparent. Currently, existing technologies mainly improve material performance by adjusting the alloy composition of the composite tape core material. However, their composition design and process control are still limited to localized optimization and cannot meet the requirement of simultaneously improving both strength and corrosion resistance. Summary of the Invention

[0004] The purpose of this invention is to solve the problems mentioned in the background art above, and to provide a high-strength corrosion-resistant aluminum alloy composite strip for radiators of engineering machinery and its preparation method.

[0005] A high-strength corrosion-resistant aluminum alloy composite strip for radiators of engineering machinery includes a first brazing layer, a core material, and a second brazing layer; the first and second brazing layers are both made of 4004 aluminum alloy, and the core material is made of modified 3-series aluminum alloy.

[0006] Furthermore, the first brazing layer and the second brazing layer are both made of 4004 aluminum alloy, and the mass percentage of the 4004 aluminum alloy is Si: 9.0%~10.5%, Fe≤0.8%, Cu≤0.25%, Mn≤0.1%, Mg: 1.0%~2.0%, Zn≤0.2% and the balance Al.

[0007] Furthermore, the core material is a modified 3-series aluminum alloy, wherein the modified 3-series aluminum alloy has the following mass percentages: Si: 0.05%~0.25%, Fe: 0.1%~0.3%, Cu: 0.3%~0.6%, Mn: 1.2%~1.6%, Mg: 0.1%~0.3%, Ti: 0.05%~0.2%, and the balance Al.

[0008] The above-mentioned method for preparing a high-strength corrosion-resistant aluminum alloy composite strip for radiators of engineering machinery comprises the following steps:

[0009] I. Smelting of the core material:

[0010] Pure aluminum ingots, pure magnesium ingots, Al-Mn alloys, Al-Cu alloys, and Al-Ti alloys were weighed out as raw materials according to the following mass percentages: Si: 0.05%~0.25%, Fe: 0.1%~0.3%, Cu: 0.3%~0.6%, Mn: 1.2%~1.6%, Mg: 0.1%~0.3%, Ti: 0.05%~0.2%, and the balance Al. They were then placed in a melting furnace and melted at 710℃~760℃ to obtain molten aluminum.

[0011] II. Casting of the core material:

[0012] The above-mentioned molten aluminum is sequentially processed through a converter, refining, settling, degassing, and filtration before being cast. After casting, it is sawed and milled to obtain the core material.

[0013] III. Composite Hot Rolling:

[0014] Two portions of 4004 aluminum alloy are taken as the first brazing layer and the second brazing layer, respectively. Then, the first brazing layer, the core material and the second brazing layer are placed and overlapped in sequence to obtain a composite billet. The billet is then fixed by welding and hot-rolled to a final thickness of 4mm to obtain a hot-rolled coil.

[0015] IV. Cold rolling:

[0016] The hot-rolled coil is subjected to multiple cold rolling passes to finally obtain a high-strength corrosion-resistant aluminum alloy composite strip for engineering machinery radiators with a finished thickness of 0.2mm~1.2mm, thus completing the preparation method described above.

[0017] Furthermore, the core material described in step two has a length of 1000~5000mm, a width of 100~2000mm, and a thickness of 40~400mm.

[0018] Furthermore, the mass percentage of the 4004 aluminum alloy mentioned in step three is Si: 9.0%~10.5%, Fe≤0.8%, Cu≤0.25%, Mn≤0.1%, Mg: 1.0%~2.0%, Zn≤0.2%, and the balance Al.

[0019] Furthermore, in step three, the first and second brazing layers have the same dimensions: a length of 1000-5000 mm, a width of 100-2000 mm, and a thickness of 2-80 mm.

[0020] Furthermore, in step three, the welding and fixing is performed by manual arc welding, spot welding is carried out along the joints around the composite blank, the spacing between the weld spots is 20~30mm, the welding rod is ER4043, the welding current is 80~120A, and the arc voltage is 18~22V.

[0021] Furthermore, in step three, the hot rolling process involves a heating temperature of 440℃~480℃ and a holding time of 5h~8h.

[0022] Furthermore, in step four, intermediate annealing is required before the last cold rolling in the multi-pass cold rolling process. The intermediate annealing temperature is 400℃~440℃, and the holding time at the temperature is 2h~4h. The cold rolling rate of the last pass is 15%~20%.

[0023] Advantages of this invention:

[0024] This invention optimizes the alloy composition by adding Cu and Mg elements to achieve solid solution strengthening and precipitation strengthening, significantly improving the mechanical properties of the aluminum alloy composite strip. Furthermore, by controlling the Fe and Si content, this invention reduces the size and quantity of the second phase, thereby decreasing pitting corrosion, while the addition of Ti promotes uniform corrosion. Simultaneously, the optimized alloy composition results in the formation of a 20-60 μm wide, high-density precipitate plate (BDP) band with reduced potential at the interface between the core material and the brazed layer after brazing, providing sacrificial anode protection. The optimized manufacturing process promotes the formation of large-grained structures in the core material after brazing, reducing corrosion pathways. Therefore, the corrosion resistance of the composite strip is significantly improved. Through this invention, the aluminum alloy composite strip possesses both high strength and excellent corrosion resistance, providing a foundation for the development of lightweight materials.

[0025] The high-strength corrosion-resistant aluminum alloy composite strip for radiators of engineering machinery prepared in this invention has a core grain size of 180um~250um after brazing; the maximum size of the second phase in the microstructure of the core after brazing is ≤5um, and the area percentage is ≤2%.

[0026] This invention is applicable to the preparation of high-strength corrosion-resistant aluminum alloy composite strips for radiators of engineering machinery and its application in the field of vacuum brazing of engineering machinery. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the structure of the high-strength corrosion-resistant aluminum alloy composite strip for radiators of engineering machinery in this invention, wherein: 1 represents the brazing layer, 2 represents the core material, and 3 represents the brazing layer;

[0028] Figure 2 Comparison of SWAAT salt spray corrosion cross-sectional morphology of aluminum alloy composite strips prepared in the examples and comparative examples 20 days after brazing;

[0029] Figure 3 Comparative metallographic images of the brazed aluminum alloy composite strips prepared in the examples and comparative examples;

[0030] Figure 4 Comparative diagrams showing the microstructure of the core material of the aluminum alloy composite strips prepared in the examples and comparative examples after brazing.

[0031] Figure 5 The diagram shows a comparison of the potential distribution at the interface between the core material and the residual brazing layer of the aluminum alloy composite strips prepared in the examples and comparative examples. Detailed Implementation

[0032] The technical solution of the present invention is not limited to the specific embodiments listed below, but also includes any combination of the specific embodiments.

[0033] Specific implementation method one: Combining Figure 1 As shown in the figure, this embodiment of a high-strength corrosion-resistant aluminum alloy composite strip for radiators of engineering machinery includes a first brazing layer 1, a core material 2, and a second brazing layer 3; the first brazing layer 1 and the second brazing layer 3 are both made of 4004 aluminum alloy, and the core material 2 is made of modified 3-series aluminum alloy.

[0034] Specific Implementation Method Two: This implementation method differs from Specific Implementation Method One in that the first brazing layer 1 and the second brazing layer 3 are both made of 4004 aluminum alloy. The mass percentage of the 4004 aluminum alloy is Si: 9.0%~10.5%, Fe≤0.8%, Cu≤0.25%, Mn≤0.1%, Mg: 1.0%~2.0%, Zn≤0.2%, and the balance is Al. Everything else is the same as in Specific Implementation Method One.

[0035] Specific Implementation Method Three: This implementation method differs from Specific Implementation Method One in that the core material 2 is made of modified 3-series aluminum alloy. The modified 3-series aluminum alloy has the following mass percentages: Si: 0.05%~0.25%, Fe: 0.1%~0.3%, Cu: 0.3%~0.6%, Mn: 1.2%~1.6%, Mg: 0.1%~0.3%, Ti: 0.05%~0.2%, and the balance Al. Everything else is the same as in Specific Implementation Method One.

[0036] Specific Implementation Method Four: This implementation method discloses a method for preparing a high-strength, corrosion-resistant aluminum alloy composite strip for radiators in engineering machinery, which is carried out according to the following steps:

[0037] I. Melting of Core Material 2:

[0038] Pure aluminum ingots, pure magnesium ingots, Al-Mn alloys, Al-Cu alloys, and Al-Ti alloys were weighed out as raw materials according to the following mass percentages: Si: 0.05%~0.25%, Fe: 0.1%~0.3%, Cu: 0.3%~0.6%, Mn: 1.2%~1.6%, Mg: 0.1%~0.3%, Ti: 0.05%~0.2%, and the balance Al. They were then placed in a melting furnace and melted at 710℃~760℃ to obtain molten aluminum.

[0039] II. Casting of core material 2:

[0040] The above-mentioned molten aluminum is sequentially processed through a converter, refining, settling, degassing and filtering before casting. After casting, it is sawed and milled to obtain core material 2.

[0041] III. Composite Hot Rolling:

[0042] Two portions of 4004 aluminum alloy are taken as the first brazing layer 1 and the second brazing layer 3, respectively. Then, the first brazing layer 1, the core material 2, and the second brazing layer 3 are placed and overlapped in sequence to obtain a composite billet. The billet is then fixed by welding and hot-rolled to a final thickness of 4mm to obtain a hot-rolled coil.

[0043] IV. Cold rolling:

[0044] The hot-rolled coil is subjected to multiple cold rolling passes to finally obtain a high-strength corrosion-resistant aluminum alloy composite strip for engineering machinery radiators with a finished thickness of 0.2mm~1.2mm, thus completing the preparation method described above.

[0045] In step one of this embodiment, Si and Fe originate from impurities.

[0046] In this embodiment, the specific dimensions of the first brazing layer 1, the core material 2, and the second brazing layer 3 are adjusted according to the finished product dimensions and the coverage rate; the coverage rate is controlled at 5%~20%, and the coverage rate = [(thickness of the first brazing layer or the thickness of the second brazing layer) / total thickness of the composite blank] × 100%.

[0047] Specific Implementation Method Five: This implementation method differs from Specific Implementation Method Four in that the core material 2 mentioned in step two has a length of 1000~5000mm, a width of 100~2000mm, and a thickness of 40~400mm. Other steps and parameters are the same as in Specific Implementation Method Four.

[0048] Specific Implementation Method Six: This implementation method differs from Specific Implementation Method Four in that the mass percentage of the 4004 aluminum alloy mentioned in step three is Si: 9.0%~10.5%, Fe≤0.8%, Cu≤0.25%, Mn≤0.1%, Mg: 1.0%~2.0%, Zn≤0.2%, and the balance Al. Other steps and parameters are the same as in Specific Implementation Method Four.

[0049] Specific Implementation Method Seven: This implementation method is the same as Specific Implementation Method Four in that the first brazing layer 1 and the second brazing layer 3 in step three have the same dimensions: a length of 1000~5000mm, a width of 100~2000mm, and a thickness of 2~80mm. Other steps and parameters are the same as in Specific Implementation Method Four.

[0050] Specific Implementation Method Eight: This implementation method differs from Specific Implementation Method Four in that the welding and fixing in step three is performed using manual electric arc welding. Spot welding is carried out along the joints around the composite blank, with a weld spacing of 20-30mm. The welding rod is ER4043, the welding current is 80-120A, and the arc voltage is 18-22V. Other steps and parameters are the same as in Specific Implementation Method Four.

[0051] Specific Implementation Method Nine: This implementation method differs from Specific Implementation Method Four in that, in step three, the hot rolling process involves a heating temperature of 440℃~480℃ and a holding time of 5h~8h. Other steps and parameters are the same as in Specific Implementation Method Four.

[0052] Specific Implementation Method Ten: This implementation method differs from Specific Implementation Method Four in that, in step four, intermediate annealing is required before the final cold rolling in the multi-pass cold rolling process. The intermediate annealing temperature is 400℃~440℃, and the holding time at that temperature is 2h~4h. The final cold rolling rate is 15%~20%. Other steps and parameters are the same as in Specific Implementation Method Four.

[0053] The beneficial effects of the present invention are verified through the following embodiments:

[0054] The following description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

[0055] Example 1:

[0056] A method for preparing a high-strength, corrosion-resistant aluminum alloy composite strip for radiators in engineering machinery, comprising the following steps:

[0057] I. Melting of Core Material 2:

[0058] Pure aluminum ingots, pure magnesium ingots, Al-Mn alloys, Al-Cu alloys, and Al-Ti alloys were weighed out as raw materials according to the following mass percentages: Si: 0.05%~0.25%, Fe: 0.1%~0.3%, Cu: 0.3%~0.6%, Mn: 1.2%~1.6%, Mg: 0.1%~0.3%, Ti: 0.05%~0.2%, and the balance Al. They were then placed into a melting furnace and melted at 740℃ to obtain molten aluminum.

[0059] II. Casting of core material 2:

[0060] The above-mentioned molten aluminum is sequentially processed through a converter, refining, settling, degassing and filtering before casting. After casting, it is sawed and milled to obtain core material 2.

[0061] III. Composite Hot Rolling:

[0062] Two portions of 4004 aluminum alloy are taken as the first brazing layer 1 and the second brazing layer 3, respectively. Then, the first brazing layer 1, the core material 2, and the second brazing layer 3 are placed and overlapped in sequence to obtain a composite billet. The billet is then fixed by welding and hot-rolled to a final thickness of 4mm to obtain a hot-rolled coil.

[0063] IV. Cold rolling:

[0064] The hot-rolled coil is subjected to multiple cold rolling passes to finally obtain a high-strength corrosion-resistant aluminum alloy composite strip for engineering machinery radiators with a finished thickness of 0.6 mm, thus completing the preparation method described above.

[0065] In step two of this embodiment, the core material 2 has a length of 1000~5000mm, a width of 100~2000mm, and a thickness of 40~400mm.

[0066] In step three of this embodiment, the mass percentage of the 4004 aluminum alloy is Si: 9.0%~10.5%, Fe≤0.8%, Cu≤0.25%, Mn≤0.1%, Mg: 1.0%~2.0%, Zn≤0.2%, and the balance Al.

[0067] In step three of this embodiment, the first brazing layer 1 and the second brazing layer 3 have the same dimensions: 1000-5000 mm in length, 100-2000 mm in width, and 2-80 mm in thickness.

[0068] The welding and fixing described in step three of this embodiment is as follows: manual electric arc welding is used to spot weld and fix the composite blank around the joint. The spacing between the welding points is 20~30mm. The welding rod is ER4043, the welding current is 80~120A, and the arc voltage is 18~22V.

[0069] In step three of this embodiment, the hot rolling process involves heating at 450°C and holding for 6 hours.

[0070] In step four of this embodiment, an intermediate annealing process is required before the last cold rolling in the multi-pass cold rolling process. The intermediate annealing temperature is 420℃, and the holding time at the temperature is 2 hours. The cold rolling rate of the last pass is 15%.

[0071] In this embodiment, the specific dimensions of the first brazing layer, the core material, and the second brazing layer are adjusted according to the finished product dimensions and the coverage rate; the coverage rate is controlled at 15%, and the coverage rate = [(thickness of the first brazing layer or the thickness of the second brazing layer) / total thickness of the composite blank] × 100%.

[0072] In step one of this embodiment, the composition of core material 2 is shown in Table 1.

[0073] This embodiment presents a schematic diagram of the structure of the high-strength corrosion-resistant aluminum alloy composite strip for engineering machinery radiators, as shown below. Figure 1 As shown.

[0074] Example 2:

[0075] The differences between this embodiment and Embodiment 1 are as follows: In step one, the composition of core material 2 is as shown in Table 1, and it is melted at 750℃; the coverage rate is controlled at 10%; in step three, the hot rolling is carried out at a heating temperature of 480℃ and a holding time of 8 hours; in step four, the final cold rolling in the multi-pass cold rolling requires intermediate annealing before the last cold rolling, with an intermediate annealing temperature of 400℃ and a holding time of 3 hours; the final cold rolling rate is 20%; finally, a high-strength corrosion-resistant aluminum alloy composite strip for engineering machinery radiators with a finished thickness of 0.8mm is obtained. Everything else is the same as in Embodiment 1.

[0076] Comparative Example 1:

[0077] The difference between this embodiment and Embodiment 1 is as follows: the composition of core material 2 in step one is as shown in Table 1; intermediate annealing is required before the last cold rolling in the multi-pass cold rolling in step four, the intermediate annealing temperature is 400℃, and the holding time at the temperature is 3h; the cold rolling rate of the last pass is 25%. Everything else is the same as in Embodiment 1.

[0078] Comparative Example 2:

[0079] The difference between this embodiment and Embodiment 2 is that the composition of core material 2 in step one is as shown in Table 1; the final cold rolling rate is 25%. Everything else is the same as in Embodiment 2.

[0080] Table 1. Alloy composition (wt.%) of core material 2 in the examples and comparative examples

[0081]

[0082] result:

[0083] The mechanical properties of the aluminum alloy composite strips prepared in the above examples and comparative examples before and after brazing were tested. Brazing was carried out in a vacuum brazing furnace at a temperature of 600℃ for 5 minutes. The results are shown in Table 2, which contains the mechanical property data of the aluminum alloy composite strips prepared in the examples and comparative examples. As can be seen from Table 2, the tensile and yield strengths of the aluminum alloy composite strips prepared in Examples 1 and 2 before and after brazing are much higher than those in Comparative Examples 1 and 2.

[0084] Table 2. Mechanical properties of aluminum alloy composite strips prepared in the examples and comparative examples.

[0085]

[0086] The aluminum alloy composite strips prepared in the examples and comparative examples were brazed and subjected to a 20-day SWAAT salt spray corrosion test to determine the maximum corrosion depth. Brazing was performed in a vacuum brazing furnace at a temperature of 600℃ for 5 minutes. The results are shown in Table 3, and the cross-sectional corrosion morphology is as follows: Figure 2 As shown. From Figure 2 As shown in Table 3, the SWAAT salt spray corrosion morphology of the aluminum alloy composite strips prepared in Examples 1 and 2 after brazing for 20 days was mainly uniform corrosion, with maximum corrosion depths of 43.4 μm and 51.0 μm, respectively, indicating a relatively mild corrosion degree. In contrast, the SWAAT salt spray corrosion morphology of the aluminum alloy composite strips prepared in Comparative Examples 1 and 2 after brazing for 20 days was pitting corrosion, with maximum corrosion depths of 198.3 μm and 203 μm, respectively, indicating a more severe corrosion degree. Therefore, the corrosion resistance of the aluminum alloy composite strips prepared in the examples of this invention is far superior to that of the comparative examples.

[0087] Table 3. Results of copper-accelerated salt spray corrosion in the examples and comparative examples.

[0088]

[0089] To further investigate the corrosion resistance mechanism of the aluminum alloy composite strip of the present invention, metallographic structure and microstructure analysis were performed on the core material of the aluminum alloy composite strip prepared in Example 1 and Comparative Example 1 after brazing. Brazing was carried out in a vacuum brazing furnace at a temperature of 600℃ for 5 minutes. Figure 3 and Figure 4 As shown. From Figure 3 It can be seen that the core grain size of the aluminum alloy composite strip prepared in Example 1 after brazing is 210.5 μm, while the core grain size of the aluminum alloy composite strip prepared in Comparative Example 1 after brazing is 168.9 μm. The grain structure of the core material after brazing in Example 1 is much larger than that in the Comparative Example. Figure 4It can be seen that the maximum size of the second phase of the core material of the aluminum alloy composite strip prepared in Example 1 after brazing is 4.3 μm, and the area percentage is 1.6%; while the maximum size of the second phase of the core material of the aluminum alloy composite strip prepared in Comparative Example 1 after brazing is 7.8 μm, and the area percentage is 3.8%. The size and area percentage of the second phase of the core material microstructure after brazing in the Example 1 are much smaller than those in the Comparative Example.

[0090] To further investigate the corrosion resistance mechanism of the aluminum alloy composite strip of the present invention, scanning Kelvin probe analysis was performed on the interface region between the core material and the brazing layer of the aluminum alloy composite strips prepared in Example 1 and Comparative Example 1 after brazing. The results are as follows: Figure 5 As shown. From Figure 5 It can be seen that after brazing, the brazed layer of the aluminum alloy composite strip prepared in Example 1 forms a BDP region with a low potential at the interface between the brazed layer and the core material. This region can play a protective role for the sacrificial anode. However, after brazing, the potential of the diffusion region of the aluminum alloy composite strip prepared in Comparative Example 1 is not significantly different from that of the core material, and it cannot play a protective role.

[0091] In summary, the aluminum alloy composite strip prepared by this invention exhibits high strength and high corrosion resistance, mainly due to the following factors:

[0092] (1) Cu and Mg elements play a role in solid solution strengthening and precipitation strengthening, thereby improving the mechanical properties of the composite strip of the present invention;

[0093] (2) The smaller quantity and size of the second phase reduced pitting corrosion, and the Ti element promoted uniform corrosion. The appropriate preparation process enabled the composite band to have a large grain structure after brazing, which reduced the grain boundary corrosion channels.

[0094] (3) After brazing, a low potential BDP region is formed at the interface between the brazed layer and the core material, which plays a protective role as a sacrificial anode. The combined effect of these three aspects significantly improves the corrosion resistance of the composite strip of the present invention. Compared with existing aluminum alloy composite strips, the aluminum alloy composite strip prepared by the present invention has both high mechanical properties and excellent corrosion resistance, which is conducive to promoting the lightweight and high reliability of radiators in the field of engineering machinery.

Claims

1. A high-strength corrosion-resistant aluminum alloy composite strip for radiators in engineering machinery, comprising a first brazing layer (1), a core material (2), and a second brazing layer (3); characterized in that... The first brazing layer (1) and the second brazing layer (3) are both made of 4004 aluminum alloy, and the core material (2) is made of modified 3 series aluminum alloy.

2. The high-strength corrosion-resistant aluminum alloy composite strip for radiators of engineering machinery according to claim 1, characterized in that... The first brazing layer (1) and the second brazing layer (3) are both made of 4004 aluminum alloy. The mass percentage of the 4004 aluminum alloy is Si: 9.0%~10.5%, Fe≤0.8%, Cu≤0.25%, Mn≤0.1%, Mg: 1.0%~2.0%, Zn≤0.2% and the balance Al.

3. The high-strength corrosion-resistant aluminum alloy composite strip for radiators of engineering machinery according to claim 1, characterized in that... The core material (2) is made of modified 3-series aluminum alloy, and the mass percentage of the modified 3-series aluminum alloy is Si: 0.05%~0.25%, Fe: 0.1%~0.3%, Cu: 0.3%~0.6%, Mn: 1.2%~1.6%, Mg: 0.1%~0.3%, Ti: 0.05%~0.2% and the balance Al.

4. The method for preparing a high-strength corrosion-resistant aluminum alloy composite strip for radiators of engineering machinery as described in claim 1, characterized in that... It proceeds in the following steps: I. Melting of core material (2): Pure aluminum ingots, pure magnesium ingots, Al-Mn alloys, Al-Cu alloys, and Al-Ti alloys were weighed out as raw materials according to the following mass percentages: Si: 0.05%~0.25%, Fe: 0.1%~0.3%, Cu: 0.3%~0.6%, Mn: 1.2%~1.6%, Mg: 0.1%~0.3%, Ti: 0.05%~0.2%, and the balance Al. They were then placed in a melting furnace and melted at 710℃~760℃ to obtain molten aluminum. II. Casting of core material (2): The above-mentioned molten aluminum is successively passed through a converter, refining, settling, degassing and filtering before casting. After casting, the aluminum is sawed and milled to obtain core material (2). III. Composite Hot Rolling: Two portions of 4004 aluminum alloy were taken as the first brazing layer (1) and the second brazing layer (3) respectively. Then, the first brazing layer (1), the core material (2), and the second brazing layer (3) were placed and overlapped in sequence to obtain a composite billet. The billet was then fixed by welding and hot-rolled to a final thickness of 4mm to obtain a hot-rolled coil. IV. Cold rolling: The hot-rolled coil is subjected to multiple cold rolling passes to finally obtain a high-strength corrosion-resistant aluminum alloy composite strip for engineering machinery radiators with a finished thickness of 0.2mm~1.2mm, thus completing the preparation method described above.

5. The method for preparing a high-strength corrosion-resistant aluminum alloy composite strip for radiators of engineering machinery according to claim 4, characterized in that... The core material (2) mentioned in step two has a length of 1000~5000mm, a width of 100~2000mm, and a thickness of 40~400mm.

6. The method for preparing a high-strength corrosion-resistant aluminum alloy composite strip for radiators of engineering machinery according to claim 4, characterized in that... The mass percentage of the 4004 aluminum alloy mentioned in step three is Si: 9.0%~10.5%, Fe≤0.8%, Cu≤0.25%, Mn≤0.1%, Mg: 1.0%~2.0%, Zn≤0.2%, and the balance Al.

7. The method for preparing a high-strength corrosion-resistant aluminum alloy composite strip for radiators of engineering machinery according to claim 4, characterized in that... In step three, the first brazing layer (1) and the second brazing layer (3) have the same size specifications, with a length of 1000~5000mm, a width of 100~2000mm, and a thickness of 2~80mm.

8. The method for preparing a high-strength corrosion-resistant aluminum alloy composite strip for radiators of engineering machinery according to claim 4, characterized in that... The welding and fixing described in step three: manual electric arc welding is used to spot weld and fix the composite blank around the joint. The spacing between the welding points is 20~30mm. The welding rod is ER4043, the welding current is 80~120A, and the arc voltage is 18~22V.

9. The method for preparing a high-strength corrosion-resistant aluminum alloy composite strip for radiators of engineering machinery according to claim 4, characterized in that... The hot rolling process in step three involves heating at a temperature of 440℃ to 480℃ and holding for 5 to 8 hours.

10. The method for preparing a high-strength corrosion-resistant aluminum alloy composite strip for radiators of engineering machinery according to claim 4, characterized in that... In step four, intermediate annealing is required before the last cold rolling in the multi-pass cold rolling process. The intermediate annealing temperature is 400℃~440℃, and the holding time at the temperature is 2h~4h. The cold rolling rate of the last pass is 15%~20%.

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