Corrosion-resistant aluminum alloy based on microalloying and preparation method

Abstract

The invention belongs to the technical field of alloy preparation, and discloses a corrosion-resistant aluminum alloy based on microalloying and a preparation method, and the aluminum alloy comprises the following components in percentage by mass: 0.01%-0.25% of Si, 0.01%-0.55% of Fe, 0.001%-0.15% of Cu, 1.1%-1.2% of Mn, 0.001%-0.01% of Mg, 0.01%-0.15% of Cr, 0.01%-0.2% of Ni, 0.01%-0.05% of Zn and the balance of Al and inevitable impurities. While the corrosion resistance of the aluminum alloy is improved, the good mechanical property of the aluminum alloy pipe is kept, and the practicability is high. The preparation method specifically comprises the following steps of raw material melting, slag removal treatment, primary alloying, refining and degassing, secondary degassing, filtering and casting, soaking treatment and forming machining and annealing. The method is simple, preparation is easy, the high-performance aluminum alloy pipe can be stably produced without complex transformation of an existing production process, and the process compatibility is high.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of alloy preparation, and in particular to a corrosion-resistant aluminum alloy based on micro-alloying and a preparation method thereof. BACKGROUND

[0002] With the global emphasis on energy saving and emission reduction and sustainable development, and the in-depth implementation of the "double carbon" strategy, the air conditioning industry is facing unprecedented challenges and opportunities. Among them, reducing production costs and alleviating the dependence on Cu resources have become one of the focuses of the industry. Based on this, the "aluminum to save Cu" technology has emerged as the times require, becoming an important direction for the innovation of air conditioner heat exchanger materials. 3 series aluminum alloys are widely used in the field of aluminum pipes for air conditioner heat exchangers due to their good formability and thermal conductivity.

[0003] However, the corrosion resistance of traditional 3 series aluminum alloys (such as 3003 and 3103 aluminum alloys) cannot meet the increasingly stringent application environment requirements. In harsh working conditions of high temperature, high humidity, and possible contact with acidic condensate water or defrosting chemicals, they are prone to pitting corrosion, intergranular corrosion, and even stress corrosion cracking, leading to heat exchanger leakage failure, which seriously affects the reliability and service life of air conditioners. The root cause of the poor corrosion resistance of 3 series aluminum alloys lies in the coarse Fe-rich phase in the aluminum alloy microstructure, such as Al(FeMn)Si phase. These high-potential cathode phases, when in contact with the electrolyte, will form a galvanic couple with the aluminum matrix, accelerating the anodic dissolution of the matrix and becoming the starting point of corrosion.

[0004] To address the above problems, the existing technology proposes a number of solutions, mainly divided into two categories: one is to modify the composition of the aluminum alloy matrix material, to improve corrosion resistance by reducing Fe content or improving melt purity, or to try adding rare earth elements for alloying modification, such as the technical solution disclosed in patent CN117127061A, which reduces the Fe content and adds trace amounts of Ti and Cr to prepare an aluminum alloy pipe with lower strength, better plasticity, and corrosion resistance. The other category focuses on the improvement of aluminum pipe surface treatment process, enhancing corrosion resistance through coating or plating, such as the technical solution disclosed in patent CN218329510U, which coats a layer of zinc-aluminum alloy on the outer surface of the internal thread aluminum pipe, making the aluminum pipe resistant to salt spray test for more than 1000 hours.

[0005] Although the existing technology has certain improvement effect in improving corrosion resistance, it still has the following defects: 1. The composition modification strategy can effectively improve the corrosion resistance, but it significantly increases the cost of raw materials and the complexity of the process, making it difficult to meet the requirements of large-scale production; 2. Surface treatment processes not only increase production costs due to the additional treatment process introduced, but also may damage the processing performance of the material, such as plasticity and weldability, and bring challenges to the subsequent manufacturing process. SUMMARY

[0006] The present application aims to provide a micro-alloyed corrosion-resistant aluminum alloy which improves the corrosion resistance of the aluminum alloy while maintaining the good mechanical properties of the aluminum alloy pipe, and has strong practicality.

[0007] The technical scheme adopted to achieve the purpose of the present application is: A micro-alloyed corrosion-resistant aluminum alloy, by mass percentage, comprises the following component ingredients: Si: 0.01% to 0.25%, Fe: 0.01% to 0.55%, Cu: 0.001% to 0.15%, Mn: 1.1% to 1.2%, Mg: 0.001% to 0.01%, Cr: 0.01% to 0.15%, Ni: 0.01% to 0.2%, Zn: 0.01% to 0.05%, and the rest is Al and unavoidable impurities.

[0008] Further, by mass percentage, comprises the following component ingredients: Si: 0.01% to 0.20%, Fe: 0.01% to 0.35%, Cu: 0.001% to 0.15%, Mn: 1.1% to 1.2%, Mg: 0.001% to 0.01%, Cr: 0.01% to 0.15%, Ni: 0.01% to 0.2%, Zn: 0.01% to 0.05%, and the rest is Al and unavoidable impurities.

[0009] Further, by mass percentage, comprises the following component ingredients: Si: 0.01% to 0.15%, Fe: 0.01% to 0.25%, Cu: 0.001% to 0.15%, Mn: 1.1% to 1.2%, Mg: 0.001% to 0.01%, Cr: 0.01% to 0.15%, Ni: 0.01% to 0.2%, Zn: 0.01% to 0.05%, and the rest is Al and unavoidable impurities.

[0010] Further, by mass percentage, comprises the following component ingredients: Si: 0.01% to 0.10%, Fe: 0.01% to 0.15%, Cu: 0.001% to 0.15%, Mn: 1.1% to 1.2%, Mg: 0.001% to 0.01%, Cr: 0.01% to 0.15%, Ni: 0.01% to 0.2%, Zn: 0.01% to 0.05%, and the rest is Al and unavoidable impurities.

[0011] Furthermore, the corrosion-resistant aluminum alloy pipe based on microalloying has a tensile strength of 110–130 MPa, an elongation of ≥40%, and a salt spray corrosion resistance time of 800–1300 h.

[0012] Another objective of this invention is to provide a corrosion-resistant aluminum alloy based on microalloying, which is simple to prepare, easy to prepare, and can stably produce high-performance aluminum alloy pipes without complex modifications to existing production processes, and has high process compatibility.

[0013] The technical solution adopted to achieve the purpose of this invention is: A method for preparing a corrosion-resistant aluminum alloy based on microalloying specifically includes the following steps: Step S1: Raw material melting. Pure aluminum ingot raw material is put into a melting furnace for melting to obtain molten liquid one. Step S2, slag removal: Sprinkle the slag remover into the first melt and stir to mix evenly to obtain aluminum liquid. Then remove the slag from the surface of the aluminum liquid to obtain the second melt. Step S3, initial alloying: add intermediate alloy or pure metal to melt two and stir evenly to obtain melt three; Step S4, refining and degassing: add refining agent to melt three, stir and remove slag, and pass pure argon gas to remove gas. After standing, remove the floating slag on the liquid surface to obtain melt four. Step S5, secondary degassing and filtration casting: pure argon gas is introduced into the molten liquid to degas it, then aluminum titanium boron wire is added, melted and degassed again, and then the molten liquid is filtered through a filter box and cast to obtain an ingot. Step S6, heat treatment: cut the ingot into short aluminum alloy round casting rods, keep them warm in a heat treatment furnace, and then cool them naturally. Step S7, forming and annealing: The aluminum rod is extruded, drawn and threaded in sequence, and finally annealed to obtain the alloy product.

[0014] Furthermore, the melting temperature in step S1 is 730–760°C; During the alloying process in step S3, the temperature of the second melt is maintained at 730–760°C; When adding the refining agent in step S4, control the temperature of the molten liquid three to be 750-790℃; The temperature of the molten liquid in step S5 during the secondary degassing process is 740–770°C. In step S6, the temperature for heat preservation in the soaking furnace is 590–620℃. The annealing temperature for the finished product in step S7 is 420-430℃.

[0015] Furthermore, in step S4, pure argon gas is introduced for degassing for 15-20 minutes, and then the liquid is allowed to stand for 50-60 minutes before removing the scum from the surface.

[0016] Furthermore, in step S5, after purging with pure argon gas for 8-12 minutes, aluminum-titanium-boron wire is added, and after the aluminum-titanium-boron wire melts, it is degassed again for 4-6 minutes.

[0017] Furthermore, in step S6, the heat soaking process is maintained for 10 to 15 hours.

[0018] The beneficial effects of this invention are as follows: 1. This invention reduces the formation of coarse Fe-rich phases by lowering the Fe and Si content, and at the same time, by adding trace elements such as Ni, Cu, and Cr to dissolve them in the aluminum matrix, the potential difference between the aluminum matrix and the second phase compound is reduced, thereby reducing the formation of corrosion channels and improving the corrosion resistance of aluminum alloys. 2. The preparation method of the present invention does not require complex modification to the existing production process, and is well compatible with the existing processing flow. Without complex process modification, it can stably produce products with uniform performance that are suitable for subsequent pipe bending, flaring, brazing and other processes, ensuring that its comprehensive performance meets the stringent application requirements of air conditioning heat exchangers. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the present invention will be further described below in conjunction with the accompanying drawings and embodiments. The drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort: Fig. 1 This is a diagram showing the corrosion morphology and corrosion depth of Example 8 of the present invention after 500 hours. Fig. 2 This is a diagram showing the corrosion morphology and corrosion depth of Comparative Example 1 of the present invention after 500 hours. Fig. 3 This is a diagram showing the corrosion morphology and corrosion depth of Comparative Example 2 of the present invention after 500 hours. Fig. 4 This is a corrosion morphology diagram of Example 8 of the present invention after 1300 hours of salt spray corrosion. Fig. 5 This is a corrosion morphology diagram of Comparative Example 1 of the present invention after 800 hours of salt spray corrosion. Fig. 6 This is a corrosion morphology diagram of Comparative Example 2 of the present invention after 1000 hours of salt spray corrosion. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be described clearly and completely below. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present invention.

[0021] Example 1 A corrosion-resistant aluminum alloy based on microalloying comprises, by mass percentage: Si 0.214%, Fe 0.532%, Cu 0.145%, Mn 1.156%, Mg 0.002%, Cr 0.142%, Ni 0.124%, Zn 0.012%, with the remainder being Al and unavoidable impurities.

[0022] The method for preparing corrosion-resistant aluminum alloy based on microalloying in this embodiment includes the following steps S1 to S7.

[0023] Step S1: Raw material melting. Pure aluminum ingot raw material is put into a melting furnace for melting to obtain molten liquid one. In this step, carefully selected high-purity aluminum ingots are added to a melting furnace. In actual operation, the furnace temperature is set to 730–760°C; in this embodiment, it is specifically set to 745°C to ensure complete melting of the raw materials and to prevent overheating that could lead to element volatilization or intensified reactions.

[0024] Step S2, slag removal: Sprinkle the slag remover into the first melt and stir to mix evenly to obtain aluminum liquid. Then remove the slag from the surface of the aluminum liquid to obtain the second melt.

[0025] In this step, the slag remover mainly consists of cryolite powder, sodium chloride, potassium chloride, and silicates, and is used to remove oxides and non-metallic inclusions from the molten metal. After evenly sprinkling the slag remover into the first molten metal, stir thoroughly with a stirrer for 5-10 minutes to ensure that the slag remover comes into full contact with the impurities in the molten metal. In this embodiment, stirring for 8 minutes is preferred, but the specific stirring time can be adjusted according to the actual processing conditions. After stirring evenly and removing the slag from the surface of the aluminum melt, a relatively pure second molten metal is obtained.

[0026] Step S3, initial alloying: add intermediate alloys or pure metals such as Mn, Ni, and Cr to melt two and stir until homogeneous to obtain melt three.

[0027] In this step, the temperature of the second melt is controlled at 730–760°C to avoid excessive temperature causing element loss. In this embodiment, it is specifically set to 745°C. Then, intermediate alloys or corresponding pure metals such as aluminum-manganese alloy, aluminum-nickel alloy, and aluminum-copper alloy (Al-Mn, Al-Ni, Al-Cu) are added in a predetermined ratio, and stirred for 10–15 minutes to ensure uniform element distribution. In this embodiment, stirring for 12 minutes is preferred, but the specific stirring time can be adjusted according to the actual processing conditions.

[0028] Step S4: Refining and degassing. Add refining agent to molten liquid three, stir, skim off the slag, and introduce pure argon gas for degassing. After standing, remove the floating slag from the liquid surface to obtain molten liquid four.

[0029] In this step, the temperature of molten liquid three is controlled at 750–790°C to ensure the effective action of the subsequently added refining agent; in this embodiment, it is specifically set to 770°C. Then, a refining agent is added to molten liquid three. The main components of the refining agent are hexachloroethane and carbon tetrachloride, which are used to remove gases and small inclusions from the molten liquid. After stirring, the slag is skimmed off, and pure argon gas is introduced for degassing for 15–20 minutes; in this embodiment, 18 minutes is preferred. The specific degassing time can be adjusted according to the actual processing conditions. After degassing, the mixture is allowed to stand for 50–60 minutes; in this embodiment, 55 minutes is preferred. Then, the scum on the surface is skimmed off to obtain highly purified molten liquid four.

[0030] Step S5, secondary degassing and filtration casting: pure argon gas is introduced into the molten liquid for degassing, then aluminum-Ti-boron wire is added, melted and degassed again, and then the molten liquid is filtered through a filter box and cast to obtain an ingot.

[0031] In this step, the temperature of the molten liquid four is controlled at 740–770°C to ensure good fluidity; in this embodiment, it is specifically set to 755°C. Pure argon gas is then introduced into the molten liquid four for deep degassing for 10 minutes. Then, aluminum-Ti-boron wire is added as a grain refiner, and after it is completely melted, degassing is performed again for 5 minutes. Subsequently, the molten liquid is filtered through a filter box preheated to 200–300°C to remove minute inclusions. In this embodiment, the filter box is preferably preheated to 250°C, and the filter medium is a ceramic foam filter plate.

[0032] Step S6, heat treatment: cut the ingot into short aluminum alloy round casting rods, keep them warm in a heat treatment furnace, and then let them cool naturally.

[0033] In this step, before holding the aluminum alloy round casting in the soaking furnace, the furnace needs to be heated to 590–620°C; in this embodiment, the temperature is raised to 615°C. The holding time is 10–15 hours to homogenize the internal structure of the casting. In this embodiment, the preferred holding time is 12.5 minutes; the specific degassing time can be adjusted according to the actual processing conditions. After the heat-treated aluminum alloy round casting is removed from the soaking furnace, it undergoes a cooling process in natural air.

[0034] Step S7, forming and annealing: The aluminum rod is extruded, drawn and threaded in sequence, and finally annealed to obtain the alloy product.

[0035] In this step, the extrusion ratio is controlled between 10:1 and 30:1 to obtain the desired cross-sectional shape and dimensions. The drawing speed is controlled between 0.5 and 2 m / min to control the amount of deformation and surface quality. Thread forming is specifically performed on an internal thread forming machine to produce precise internal threads. The annealing temperature for the finished product is 420–430°C, and in this example, 425°C. After holding the annealing process for 3 hours, it is allowed to cool naturally to obtain a corrosion-resistant aluminum alloy product with excellent corrosion resistance, good mechanical properties, and machinability.

[0036] Examples 2-4 Compared with Example 1, Examples 2-4 use the same raw materials and preparation methods. The only difference is that the ratio of Si to Fe in the raw materials of Examples 2-4 is different from that of Example 1, while the ratios of other raw materials are the same, in order to explore the effect of the Si to Fe ratio on product performance.

[0037] In Example 2, the composition by mass percentage is as follows: Si: 0.171%, Fe: 0.338%, Cu: 0.145%, Mn: 1.156%, Mg: 0.002%, Cr: 0.142%, Ni: 0.124%, Zn: 0.012%, with the remainder being Al and unavoidable impurities.

[0038] In Example 3, the composition by mass percentage is as follows: Si: 0.143%, Fe: 0.213%, Cu: 0.145%, Mn: 1.156%, Mg: 0.002%, Cr: 0.142%, Ni: 0.124%, Zn: 0.012%, with the remainder being Al and unavoidable impurities.

[0039] In Example 4, the composition by mass percentage is as follows: Si: 0.087%, Fe: 0.145%, Cu: 0.145%, Mn: 1.156%, Mg: 0.002%, Cr: 0.142%, Ni: 0.124%, Zn: 0.012%, with the remainder being Al and unavoidable impurities.

[0040] Table 1 below is a comparison of the composition of Examples 1-4 by mass percentage. Table 1 Comparison of the composition of Examples 1-4 by mass percentage I. Mechanical property testing of Examples 1-4 The mechanical properties of the aluminum alloy tube samples prepared in Examples 1-4 were tested, and the specific test results are shown in Table 2 below.

[0041] Table 2 Comparison of Mechanical Properties of Aluminum Alloy Tube Samples from Examples 1-4 As shown in Table 2, in the aluminum alloy tube samples of Examples 1-4, the addition of Fe and Si gradually decreased from Examples 1 to Examples 4, but the tensile strength and yield strength of Examples 1-4 gradually increased. This indicates that when other elements remain unchanged, Fe and Si have a significant impact on the mechanical properties of the product, and the lower the Fe and Si content, the better the mechanical properties. Among Examples 1-4, Example 4 has the best overall mechanical properties; therefore, Example 4 is the preferred example among Examples 1-4.

[0042] II. Salt spray corrosion resistance test of Examples 1-4 The present invention also tested the salt spray corrosion resistance of Examples 1-4, and the specific test results are shown in Table 3 below.

[0043] Table 3 Comparison of corrosion resistance data for aluminum alloy tube samples from Examples 1-4 As shown in Table 3, the corrosion resistance time of Examples 1-4 of the present invention is relatively short. In the aluminum alloy tube samples of Examples 1-4, the amounts of Fe and Si added gradually decrease from Examples 1 to 4, but the salt spray corrosion resistance of Examples 1-4 gradually increases. This indicates that when other elements remain constant, Fe and Si have a significant impact on the corrosion resistance time of the product, and the lower the Fe and Si content, the better the corrosion resistance effect. Among Examples 1-4, Example 4 has the best overall mechanical properties; therefore, Example 4 is the preferred embodiment among Examples 1-4.

[0044] Although Examples 1-4 exhibit certain mechanical properties and corrosion resistance, the overall effect is not ideal. To further improve the mechanical properties and corrosion resistance of the aluminum alloy tube of this invention, Examples 5-8 and Comparative Examples 1-2 were designed based on Example 4 to investigate the effects of Cu, Cr, and Ni on product performance.

[0045] Examples 5-8 Compared with Example 4, Examples 5-8 use the same raw materials and preparation methods. The only difference is that the ratio of Si, Fe, Mn, Mg and Zn in the raw materials of Examples 5-8 is the same as that of Example 4, while the ratio of Cu, Cr and Ni is different.

[0046] In Example 5, the composition by mass percentage is as follows: Si: 0.087%, Fe: 0.145%, Cu: 0.102%, Mn: 1.156%, Mg: 0.002%, Cr: 0.112%, Ni: 0.101%, Zn: 0.012%, with the remainder being Al and unavoidable impurities.

[0047] In Example 6, the composition by mass percentage is as follows: Si: 0.087%, Fe: 0.145%, Cu: 0.086%, Mn: 1.156%, Mg: 0.002%, Cr: 0.094%, Ni: 0.086%, Zn: 0.012%, with the remainder being Al and unavoidable impurities.

[0048] In Example 7, the composition by mass percentage is as follows: Si: 0.087%, Fe: 0.145%, Cu: 0.019%, Mn: 1.156%, Mg: 0.002%, Cr: 0.082%, Ni: 0.045%, Zn: 0.012%, with the remainder being Al and unavoidable impurities.

[0049] In Example 8, the composition by mass percentage is as follows: Si: 0.087%, Fe: 0.145%, Cu: 0.008%, Mn: 1.156%, Mg: 0.002%, Cr: 0.076%, Ni: 0.012%, Zn: 0.012%, with the remainder being Al and unavoidable impurities.

[0050] Comparative Examples 1-2 Compared with Example 4, Comparative Examples 1-2 differ in the types of raw materials and preparation methods. The main differences are as follows: 1. Regarding raw materials: The ratio of Cu to Cr in Comparative Example 1 is different; Ti is used to replace Ni in Example 4, and the ratio is adjusted. The ratio of Cu to Ni in Comparative Example 2 is different. Ti is used to replace Cr in Example 4, and the ratio is adjusted.

[0051] In Comparative Example 1, the following components were included by mass percentage: Si: 0.087%, Fe: 0.145%, Cu: 0.043%, Mn: 1.156%, Mg: 0.002%, Cr: 0.076%, Zn: 0.012%, Ti: 0.012%, with the remainder being Al and unavoidable impurities.

[0052] In Comparative Example 2, the following components were included by mass percentage: Si: 0.087%, Fe: 0.145%, Cu: 0.101%, Mn: 1.156%, Mg: 0.002%, Ni: 0.012%, Zn: 0.012%, Ti: 0.076%, with the remainder being Al and unavoidable impurities.

[0053] 2. Regarding the preparation method: Comparative Example 1 did not add Ni in step S1, but added Ti in step S3; Comparative Example 2 did not add Cr in step S3, but added Ti.

[0054] Table 4 below is a comparison table of the composition of Examples 4-8 and Comparative Examples 1-2 by mass percentage. Table 4. Comparison of the composition of Examples 4-8 and Comparative Examples 1-2 by mass percentage I. Mechanical property testing of Examples 5-8 and Comparative Examples 1-2 The mechanical properties of the aluminum alloy tube samples prepared in Examples 5-8 and Comparative Examples 1-2 were tested, and the test results were compared with those of the sample in Example 4. The specific test results are shown in Table 5 below.

[0055] Table 5. Comparison of mechanical property data of aluminum alloy tube samples from Examples 4-8 and Comparative Examples 1-2 As shown in Table 5, the aluminum alloy tube samples of Examples 4-8 exhibit an overall tensile strength of 110-120 MPa, a yield strength ≥60 MPa, and an elongation ≥40%, demonstrating superior overall performance compared to Comparative Examples 1 and 2. This indicates that the aluminum alloy tube samples prepared using the specific raw material combination of the present invention possess excellent mechanical properties. Furthermore, in Examples 4 to 8, with constant Fe and Si additions, the tensile strength and yield strength gradually increased as the additions of Cu, Cr, and Ni gradually decreased. This indicates that, with other elements remaining constant, Cu, Cr, and Ni significantly influence the mechanical properties of the product, and lower Cu, Cr, and Ni contents result in better mechanical properties. Among Examples 4-8, Example 8 demonstrates superior tensile strength, yield strength, and elongation compared to Examples 4-8, exhibiting the best overall mechanical properties. Therefore, among Examples 4-8, Example 8 is the preferred embodiment of the present invention.

[0056] II. Salt spray corrosion resistance tests of Examples 5-8 and Comparative Examples 1-2 The present invention also tested the salt spray corrosion resistance of Examples 5-8 and Comparative Examples 1-2, and compared the test results with those of Example 4. The specific test results are shown in Table 6 below.

[0057] Table 6. Comparison of corrosion resistance data for aluminum alloy tube samples from Examples 4-8 and Comparative Examples 1-2. As shown in Table 6, the corrosion resistance time of the embodiments of the present invention is 800-1300 hours. Although the corrosion resistance time of Comparative Examples 1-2 is also within the range of this embodiment, a comprehensive analysis based on the mechanical property test results in Table 5 shows that Comparative Examples 1-2 have poor mechanical properties and cannot simultaneously achieve both corrosion resistance and mechanical properties of the aluminum alloy. However, combining the results in Tables 5 and 6, it can be seen that the present invention can improve the corrosion resistance of the aluminum alloy while maintaining good mechanical properties of the aluminum alloy pipe. Furthermore, in Examples 4-8, with the Fe and Si additions remaining constant, the salt spray corrosion resistance gradually increased as the Cu, Cr, and Ni additions decreased. This indicates that when other elements remain constant, Cu, Cr, and Ni have a significant impact on the corrosion resistance time of the product, and the lower the Cu, Cr, and Ni content, the better the corrosion resistance effect. Among Examples 4-8, Example 8 has the best overall mechanical properties and the best overall salt spray corrosion resistance. Therefore, Example 8 is the preferred embodiment of the present invention.

[0058] The present invention also provides specific test results of the corrosion morphology and corrosion depth of Example 8 and Comparative Examples 1-2 after 500 hours, as follows: Figs. 1 to 3 As shown. Furthermore, the present invention also compared the specific morphologies of Example 8 and Comparative Examples 1-2 regarding their salt spray corrosion resistance times, as shown in the following figures.Figs. 4 to 6 As shown.

[0059] according to Figs. 1 to 3 The results show that after 500 hours of salt spray corrosion, the corrosion depth of Example 8 was 203.65 μm, that of Comparative Example 1 was 339.45 μm, and that of Comparative Example 2 was 280.11 μm. Therefore, the corrosion depth of Comparative Example 1 is greater than that of Comparative Example 2, and the corrosion depths of Comparative Examples 1 and 2 are significantly greater than that of Example 8. In other words, within the same time frame, the aluminum alloy sample of Example 8 exhibits stronger corrosion resistance.

[0060] according to Figs. 4 to 6 The results show that the salt spray corrosion resistance time of Example 8 is 1300 hours, while that of Comparative Example 1 is 800 hours, and that of Comparative Example 2 is 1000 hours. Furthermore, the corrosion conditions of Comparative Examples 1 and 2 are more severe than those of Example 8. Therefore, it can be concluded that Example 8 has a longer corrosion resistance time than Comparative Examples 1 and 2, and that Example 8 is less susceptible to corrosion.

[0061] Based on the above mechanical properties and salt spray corrosion resistance test experiments, it can be seen that the present invention can significantly improve the corrosion resistance of aluminum alloy materials without significantly changing the existing production process or increasing the cost, while maintaining the mechanical properties of aluminum alloy materials.

[0062] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the scope of the present invention should be included within the protection scope of the present invention.

Claims

1. A corrosion-resistant aluminum alloy based on microalloying, characterized in that, By mass percentage, it comprises the following components: Si: 0.01%–0.25%, Fe: 0.01%–0.55%, Cu: 0.001%–0.15%, Mn: 1.1%–1.2%, Mg: 0.001%–0.01%, Cr: 0.01%–0.15%, Ni: 0.01%–0.2%, Zn: 0.01%–0.05%, with the remainder being Al and unavoidable impurities.

2. The corrosion-resistant aluminum alloy based on microalloying according to claim 1, characterized in that, By mass percentage, it comprises the following components: Si: 0.01%–0.20%, Fe: 0.01%–0.35%, Cu: 0.001%–0.15%, Mn: 1.1%–1.2%, Mg: 0.001%–0.01%, Cr: 0.01%–0.15%, Ni: 0.01%–0.2%, Zn: 0.01%–0.05%, with the remainder being Al and unavoidable impurities.

3. The corrosion-resistant aluminum alloy based on microalloying according to claim 1, characterized in that, By mass percentage, it comprises the following components: Si: 0.01%–0.15%, Fe: 0.01%–0.25%, Cu: 0.001%–0.15%, Mn: 1.1%–1.2%, Mg: 0.001%–0.01%, Cr: 0.01%–0.15%, Ni: 0.01%–0.2%, Zn: 0.01%–0.05%, with the remainder being Al and unavoidable impurities.

4. The corrosion-resistant aluminum alloy based on microalloying according to claim 1, characterized in that, By mass percentage, it comprises the following components: Si: 0.01%–0.10%, Fe: 0.01%–0.15%, Cu: 0.001%–0.15%, Mn: 1.1%–1.2%, Mg: 0.001%–0.01%, Cr: 0.01%–0.15%, Ni: 0.01%–0.2%, Zn: 0.01%–0.05%, with the remainder being Al and unavoidable impurities.

5. The corrosion-resistant aluminum alloy based on microalloying according to any one of claims 1 to 4, characterized in that, The corrosion-resistant aluminum alloy pipe based on microalloying has a tensile strength of 110-130 MPa, an elongation of ≥40%, and a salt spray corrosion resistance time of 800-1300 h.

6. A method for preparing the corrosion-resistant aluminum alloy based on microalloying as described in any one of claims 1 to 5, characterized in that, Specifically, the following steps are included: Step S1: Raw material melting. Pure aluminum ingot raw material is put into a melting furnace for melting to obtain molten liquid one. Step S2, slag removal: Sprinkle the slag remover into the first melt and stir to mix evenly to obtain aluminum liquid. Then remove the slag from the surface of the aluminum liquid to obtain the second melt. Step S3, initial alloying: add intermediate alloy or pure metal to melt two and stir evenly to obtain melt three; Step S4, refining and degassing: add refining agent to melt three, stir and remove slag, and pass pure argon gas to remove gas. After standing, remove the floating slag on the liquid surface to obtain melt four. Step S5, secondary degassing and filtration casting: pure argon gas is introduced into the molten liquid to degas it, then aluminum titanium boron wire is added, melted and degassed again, and then the molten liquid is filtered through a filter box and cast to obtain an ingot. Step S6, heat treatment: cut the ingot into short aluminum alloy round casting rods, keep them warm in a heat treatment furnace, and then cool them naturally. Step S7, forming and annealing: The aluminum rod is extruded, drawn and threaded in sequence, and finally annealed to obtain the alloy product.

7. The method for preparing corrosion-resistant aluminum alloy based on microalloying according to claim 6, characterized in that, The melting temperature in step S1 is 730–760°C; During the alloying process in step S3, the temperature of the second melt is maintained at 730–760°C; When adding the refining agent in step S4, control the temperature of the molten liquid three to be 750-790℃; The temperature of the molten liquid in step S5 during the secondary degassing process is 740–770°C. In step S6, the temperature for heat preservation in the soaking furnace is 590–620℃. The annealing temperature for the finished product in step S7 is 420-430℃.

8. The method for preparing corrosion-resistant aluminum alloy based on microalloying according to claim 6, characterized in that, In step S4, pure argon gas is introduced for degassing for 15-20 minutes, and then the liquid is allowed to stand for 50-60 minutes before removing the scum from the surface.

9. The method for preparing corrosion-resistant aluminum alloy based on microalloying according to claim 6, characterized in that, In step S5, pure argon gas is introduced for degassing for 8-12 minutes, and then aluminum-titanium-boron wire is added. After the aluminum-titanium-boron wire melts, it is degassed again for 4-6 minutes.

10. The method for preparing corrosion-resistant aluminum alloy based on microalloying according to claim 6, characterized in that, In step S6, the heat equalization process is maintained for 10 to 15 hours.

Images