Rare earth-containing corrosion-resistant wrought aluminum alloy and preparation method thereof

Abstract

The invention discloses a corrosion-resistant wrought aluminum alloy containing rare earth and a preparation method of the corrosion-resistant wrought aluminum alloy. The corrosion-resistant wrought aluminum alloy comprises, by mass, 0.05%-0.30% of Fe, 0.05%-0.25% of Si, 0.80%-1.6% of Mn, 0.01%-0.20% of Cr, 0.01%-0.30% of Ti, 0.05%-0.35% of rare earth and the balance Al and impurity elements, and the sum of the mass percentage of the impurity elements is not larger than 0.20%. By adjusting the element types and proportions of the aluminum alloy and adopting the rare earth composite refiner, matrix grain refinement and intermetallic compound modification of the aluminum alloy are achieved, the stability of a surface passivation film is improved, the local corrosion tendency is reduced, and the corrosion resistance is improved; and the maximum corrosion depth is 180 [mu] m or less after exposure for 21 days under a circulating acidic seawater salt spray test of ASTM G85 standards.

Description

Technical Field

[0001] The invention belongs to the technical field of aluminum alloy materials, and in particular relates to a corrosion-resistant deformation aluminum alloy containing rare earth and a preparation method thereof. Background Art

[0002] With the advancement of science and technology and the changes in industrial needs, replacing copper with aluminum has become an important trend in many fields. In the field of heat exchange, aluminum alloy has significant advantages as a material to replace copper. First, the density of aluminum is about one-third of that of copper, which makes aluminum alloy significantly lighter than copper at the same volume. Secondly, the price of aluminum is usually lower than that of copper, and the processing cost of aluminum is relatively low, which can effectively reduce production costs, especially in large-scale production. The economic benefits are more obvious. In addition, the processability of aluminum alloy is usually better than that of copper, which can be more easily extruded, rolled and cast, etc., and has greater flexibility and economy in manufacturing parts with complex shapes. However, the application of copper in the field of heat exchange is still dominant at present. This is because in a humid atmospheric environment, the corrosion resistance of aluminum alloy is significantly reduced, resulting in accelerated failure of heat exchange tubes or fins in the heat exchanger, and ultimately shortening the product life. Therefore, the heat exchange field is still in urgent need of reliable and corrosion-resistant aluminum alloy materials to replace copper.

[0003] The corrosion resistance of aluminum alloys is mainly affected by their microstructure and alloying elements. In aluminum alloys, alloying elements can be dissolved into the matrix or form various intermetallic compounds. These intermetallic compounds may exist as cathodes or anodes in the aluminum alloy matrix to form local corrosion cells. When the corrosion potential of these intermetallic compounds is greatly different from that of the aluminum alloy matrix, the local corrosion of the aluminum alloy will be aggravated. Therefore, the size, shape and distribution of intermetallic compounds may affect the corrosion performance. Generally speaking, small and evenly distributed intermetallic compounds can reduce the tendency of local corrosion to expand. In addition, grain refinement is also considered to be a method to improve the corrosion resistance of aluminum alloys. Studies have shown that finer grains can make the passivation film on the alloy surface denser and more stable, thereby enhancing the corrosion resistance. Rare earth composite refiners can combine the modification, refinement and purification effects of rare earths with the refinement effect of Al-Ti-B master alloys to improve or even eliminate the effect of the refinement effect of Al-Ti-B grain refiners that is prone to decline over time. Summary of the invention

[0004] The main purpose of the present invention is to provide a rare earth-containing corrosion-resistant deformable aluminum alloy. Starting from the composition design of the aluminum alloy, by reasonably matching the types and proportions of alloying elements, and using rare earth composite refiners in the melting and casting process, the grains of the alloy are significantly refined, and the fine intermetallic compounds are evenly distributed. A reliable corrosion-resistant deformable aluminum alloy material is developed to solve the problems existing in the prior art to a certain extent.

[0005] Another object of the present invention is to provide a method for preparing the rare earth-containing corrosion-resistant deformable aluminum alloy, which achieves grain refinement of the aluminum alloy and uniform distribution of intermetallic compounds by optimizing the selection of elements in the aluminum alloy.

[0006] To achieve the above object, the present invention adopts the following technical solution:

[0007] The first aspect of the present invention provides a rare earth-containing corrosion-resistant deformable aluminum alloy, which includes the following components in terms of mass percentage: Fe 0.05% to 0.30%, Si 0.05% to 0.25%, Mn 0.80% to 1.6%, Cr 0.01% to 0.20%, Ti 0.01% to 0.30%, rare earth 0.05% to 0.35%, and the remainder is Al and impurity elements, and the total mass percentage of the impurity elements is not more than 0.20%.

[0008] Preferably, the rare earth includes at least one of lanthanum (La), cerium (Ce), yttrium (Y), praseodymium (Pm), erbium (Er), neodymium (Nd), and samarium (Sm). Based on the mass of the rare earth-containing corrosion-resistant deformable aluminum alloy, the total mass percentage of the rare earth is 0.10% to 0.25%.

[0009] Preferably, the rare earth-containing corrosion-resistant deformable aluminum alloy comprises the following components in terms of mass percentage: Fe 0.05%-0.20%, Si 0.05%-0.15%, Mn 0.80%-1.10%, Cr 0.01%-0.20%, Ti 0.01%-0.25%, rare earth 0.10%-0.25%, and the remainder is Al and impurity elements, and the total mass percentage of the impurity elements is not more than 0.20%.

[0010] A second aspect of the present invention provides a method for preparing the rare earth-containing corrosion-resistant deformable aluminum alloy, comprising the following steps:

[0011] (1) providing a prefabricated raw material of pure aluminum ingot, aluminum-M master alloy, aluminum-rare earth master alloy, refining agent and rare earth composite refiner, wherein M comprises at least one of Fe, Si, Mn, Cr and Ti, and the mass percentage of each element in the prefabricated raw material satisfies the following: Fe 0.05% to 0.30%, Si 0.05% to 0.25%, Mn 0.80% to 1.6%, Cr 0.01% to 0.20%, Ti 0.01% to 0.30%, rare earth 0.05% to 0.35%, and the remainder is Al and impurity elements, and the total mass percentage of the impurity elements is not more than 0.20%;

[0012] (2) adding a pure aluminum ingot into a smelting furnace and performing a first-stage hot-melt treatment to obtain an aluminum melt;

[0013] (3) adding an aluminum-M master alloy to the aluminum melt, performing a second stage hot melt treatment, and obtaining an aluminum alloy melt;

[0014] (4) adding an aluminum-rare earth master alloy to the aluminum alloy melt, performing a third stage hot melt treatment, and obtaining a rare earth-containing aluminum alloy melt;

[0015] (5) adding a refining agent to the rare earth-containing aluminum alloy melt to perform a refining treatment to obtain a refined aluminum alloy melt;

[0016] (6) adding a rare earth composite refiner to the refined aluminum alloy melt to perform a refinement treatment to obtain a refined aluminum alloy melt;

[0017] (7) The refined aluminum alloy melt is cast and homogenized in sequence to obtain a rare earth-containing corrosion-resistant deformable aluminum alloy rod or plate.

[0018] Preferably, the aluminum-M master alloy includes at least one of an aluminum-iron master alloy, an aluminum-silicon master alloy, an aluminum-manganese master alloy, an aluminum-chromium master alloy, and an aluminum-titanium master alloy.

[0019] Preferably, the aluminum-rare earth master alloy includes at least one of aluminum-lanthanum master alloy, aluminum-cerium master alloy, aluminum-yttrium master alloy, aluminum-praseodymium master alloy, aluminum-erbium master alloy, aluminum-neodymium master alloy and aluminum-samarium master alloy.

[0020] Preferably, the rare earth composite refiner is an aluminum-titanium-boron-rare earth composite refiner, wherein the rare earth is at least one of lanthanum, cerium, yttrium, praseodymium, erbium, neodymium and samarium.

[0021] Preferably, the refining agent includes KCl, NaCl, Na 3 AlF 6 、Na 2 SiF 6 , CaF 2 , C 2 Cl 6 At least one of .

[0022] Preferably, before the first stage hot melt treatment, the process further comprises: preheating the pure aluminum ingot, the aluminum-M master alloy, the aluminum-rare earth master alloy and the rare earth composite refiner, wherein the preheating temperature is T 0 , time is t 0 , where 180℃≤T 0 ≤220℃,1h≤t 0 ≤5h.

[0023] Preferably, in step (2), the temperature of the aluminum melt is T 1 , T1 Meet: 720℃≤T 1 ≤750℃.

[0024] Preferably, in step (3), the temperature of the aluminum alloy melt is T 2 , T 2 Meet: 720℃≤T 2 ≤750℃.

[0025] Preferably, in step (4), the temperature of the rare earth-containing aluminum alloy melt is T 3 , T 3 Meet: 700℃≤T 3 ≤730℃.

[0026] Preferably, in step (5), the refining treatment comprises: a temperature conditions, adding the refining agent to the rare earth-containing aluminum alloy melt, refining for a first time t m , and let stand for a second time t n , slag removal, to obtain the refined aluminum alloy melt; wherein, 710℃≤T a ≤740℃,0.1h≤t m ≤0.25h, 0.15h≤t n ≤0.35h.

[0027] Preferably, in step (6), the refinement process comprises: b temperature conditions, adding a refiner to the refined aluminum alloy melt, refining for a third time t h , slag removal, to obtain the aluminum alloy melt after refinement treatment; wherein, 700℃≤T b ≤740℃,0.15h≤t h ≤0.5h.

[0028] Preferably, in step (7), the temperature of the homogenization treatment is T j , time is t j , where 580℃≤T j ≤620℃,10h≤t j ≤14h.

[0029] The third aspect of the present invention provides the use of the rare earth-containing corrosion-resistant deformable aluminum alloy in the preparation of heat exchanger components, and the heat exchanger components include heat exchange circular tubes, microchannel flat tubes and aluminum foil.

[0030] Preferably, the tensile strength Rm of the aluminum alloy heat exchange round tube satisfies: 100MPa≤Rm≤130MPa, the yield strength Rp0.2 satisfies: 40MPa≤Rp0.2≤55MPa, and the elongation 40%≤A≤55%;

[0031] And / or the tensile strength Rm of the aluminum alloy microchannel flat tube satisfies: 90MPa≤Rm≤108MPa, the yield strength Rp0.2 satisfies: 35MPa≤Rp0.2≤50MPa, and the elongation 45%≤A≤55%;

[0032] And / or the tensile strength Rm of the aluminum foil satisfies: 85MPa≤Rm≤135MPa, the yield strength Rp0.2 satisfies: 35MPa≤Rp0.2≤55MPa, and the elongation 35%≤A≤45%.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] (1) By adjusting the element types and proportions of the aluminum alloy and using a rare earth composite refiner to achieve matrix grain refinement of the aluminum alloy and modification of the intermetallic compounds, the stability of the surface passivation film is improved, and the tendency of local corrosion is reduced, thereby improving the corrosion resistance of the aluminum alloy. After exposure to the cyclic acidic seawater salt spray test (SWAAT) of the ASTM G85 standard for 21 days, the maximum corrosion depth is 180μm or less.

[0035] (2) By selectively adding trace amounts of rare earth elements, the hydrogen content in the aluminum melt can be significantly reduced, the porosity and porosity of the processed aluminum alloy can be reduced, and inclusions and harmful elements can be reduced, thereby achieving the effect of degassing, refining and purifying the melt.

[0036] (3) By controlling the rare earth element RE in the aluminum alloy to form complex intermetallic compounds with impurities such as Mn, Fe, and Si in the aluminum alloy matrix, the intermetallic compounds can be spheroidized. At the same time, the corrosion potential difference between the intermetallic compound containing rare earth elements and the aluminum alloy matrix is ​​reduced, thereby reducing the driving force of microgalvanic corrosion and the tendency of local corrosion.

[0037] (4) The addition of rare earth element RE refines the aluminum alloy structure. By adding rare earth composite refiner aluminum-titanium-boron-rare earth alloy, the aluminum alloy grain refinement effect can be better, the internal intermetallic compounds are evenly distributed, the pitting corrosion resistance is improved, the mechanical properties are improved, and the processing performance is excellent. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 This is the microstructure diagram of the rare earth-containing corrosion-resistant deformable aluminum alloy prepared in Example 3.

[0039] Figure 2 This is the microstructure diagram of the 3003 series aluminum alloy prepared in Comparative Example 1. DETAILED DESCRIPTION

[0040] In order to more fully understand and demonstrate the technical solutions, purposes and advantages of the present invention, the technical effects produced by the present invention are further described in detail and completely in conjunction with specific embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, not all. It should be pointed out that for those of ordinary skill in the art, other embodiments obtained without departing from the concept of the present invention all belong to the protection scope of the present invention.

[0041] The inventors of the present invention have found that active rare earth elements can form new intermetallic compounds with intermetallic compounds in aluminum alloys, for example, complex intermetallic compounds such as Al-Fe-RE and Al-Fe-Si-RE can be formed with elements such as Fe and Si. Al-Fe and Al-Fe-Si are strong cathode intermetallic compounds for aluminum alloy matrix, so local corrosion is prone to occur. The corrosion potential of intermetallic compounds containing rare earth elements such as Al-Fe-RE and Al-Fe-Si-RE is lower than that of Al-Fe and Al-Fe-Si, and the corrosion potential difference between the aluminum alloy matrix is ​​reduced, and the tendency of local corrosion is weakened, which can effectively improve the corrosion resistance of aluminum alloy. In manganese-containing aluminum alloys, rare earth elements can form complex intermetallic compounds such as Al-Mn-RE and Al-Mn-Fe-RE, which can also shorten the potential difference between the intermetallic compound and the aluminum alloy matrix. On the other hand, in addition to modifying the intermetallic compound phase, the aluminum matrix can also be refined by introducing alloy elements to make the alloy grains more refined, and the surface passivation film more dense, thereby reducing the diffusion of external corrosive ions, thereby enhancing the ability to resist corrosion.

[0042] Based on this, the present invention optimizes the selection of elements of the aluminum alloy to achieve uniform distribution of intermetallic compounds in the aluminum alloy, while reducing the corrosion potential of harmful intermetallic compounds, narrowing the corrosion potential difference between the aluminum alloy matrix and the intermetallic compounds, and reducing the tendency of harmful intermetallic compounds in the aluminum alloy material to produce local corrosion. At the same time, a rare earth composite refiner aluminum-titanium-boron-rare earth is used to refine the grains, making the surface passivation film denser and improving the ability to resist external corrosive media, thereby providing a rare earth-containing corrosion-resistant deformable aluminum alloy with excellent mechanical properties, good processing properties, good corrosion resistance and the ability to deform.

[0043] The invention provides a rare earth-containing corrosion-resistant deformable aluminum alloy, comprising the following components by mass fraction: 0.05%-0.30% Fe, 0.05%-0.25% Si, 0.80%-1.6% Mn, 0.01%-0.20% Cr, 0.01%-0.30% Ti, 0.05%-0.35% rare earth, and the remainder being Al and impurity elements, wherein the total mass percentage content of the impurity elements is not greater than 0.20%.

[0044] In the above-mentioned rare earth-containing corrosion-resistant deformable aluminum alloy of the present invention, the functions of each element are as follows:

[0045] Mn plays a very important role in regulating the microstructure and corrosion resistance. As the manganese content increases, the strength of the aluminum alloy increases, while the corrosion resistance remains unchanged. However, too high a Mn content may have a negative impact on the casting properties of the aluminum alloy. For example, if the mass percentage of manganese exceeds 1.6%, a brittle compound MnAl will be formed. 6 , this compound will reduce the plasticity of aluminum alloy and easily crack during cold working deformation. In addition, due to the 6 The corrosion potential of aluminum alloy is close to that of aluminum alloy matrix, which can inhibit the occurrence of micro-galvanic corrosion, thereby improving the overall corrosion resistance of the alloy. Therefore, by adjusting the content of manganese, the performance of aluminum alloy can be optimized in different aspects. Considering the above factors, the range of Mn content is selected to be 0.80% to 1.60%, preferably 0.80% to 1.10%.

[0046] The microstructure and properties of aluminum alloys are closely related to the content and form of Fe to a certain extent. Fe can accelerate the precipitation of Mn in the aluminum alloy solid solution and greatly reduce the solubility of Mn in the aluminum alloy matrix, so that the aluminum alloy structure can obtain finer grains during annealing. In Al-Mn cast alloys, Fe is easily enriched at the grain boundaries and easily forms (FeMn)Al with Mn elements. 6 Intermetallic compounds accelerate the precipitation of Mn, further reduce the segregation of Mn in the aluminum alloy matrix, and make the aluminum alloy structure uniform. The content of Fe in the aluminum alloy should not be too high. Excessive iron will cause (FeMn)Al 6 The compound coarsens, and the coarse (FeMn)Al 6 It will reduce the mechanical properties of aluminum alloy. At the same time, excessive Fe forms Fe-containing intermetallic compounds, which are strong cathode phases relative to the aluminum alloy matrix, and are easy to cause micro galvanic corrosion, reducing the corrosion resistance of the alloy. Considering the above factors, the Fe content should be strictly controlled below 0.3%, and the preferred Fe content range is 0.05% to 0.20%.

[0047] When there is too much Si in the aluminum alloy, the excessive silicon content may cause Si to form Al-Fe-Si phase with Fe and Al. The Al-Fe-Si phase usually has a more positive corrosion potential, higher than the aluminum alloy matrix, which may cause severe corrosion of the alloy matrix, thereby reducing the corrosion resistance of the alloy. Therefore, in the process of adding and controlling Si, it is necessary to balance between mechanical properties and corrosion properties to ensure that the aluminum alloy performs optimally in different application environments. Taking the above factors into consideration, the Si content range is selected to be 0.05% to 0.25%, and the preferred Si content range is 0.05% to 0.15%.

[0048] The addition of Cr (chromium) is conducive to grain refinement. Studies have shown that chromium can form chromate or aluminum-chromium oxide with aluminum. These oxides will form a stable protective film on the surface of the aluminum alloy. This film helps to enhance the aluminum alloy's resistance to corrosive media, especially in acidic or alkaline environments. When the oxide film is damaged, chromium can promote the rapid formation of a new oxide film to maintain the protectiveness of the surface. The Cr content ranges from 0.01% to 0.20%, preferably 0.01% to 0.15%.

[0049] Ti is a commonly used additive element in aluminum alloys. It has little effect on corrosion resistance. During processing, it is added as a refiner in the form of Al-Ti master alloy or Al-Ti-B master alloy. 3 Phase, which becomes the non-spontaneous core during crystallization and plays a role in refining the structure. The Ti content ranges from 0.01% to 0.30%, preferably from 0.01% to 0.25%.

[0050] The addition of rare earth elements (RE) helps to refine the grains of aluminum alloys, forming a finer and more uniform grain structure by limiting the growth of grains, improving the strength and hardness of the alloy, and reducing the tendency of local corrosion. At the same time, the addition of rare earth elements can form corrosion-inhibiting intermetallic compounds with other elements, reduce the corrosion potential difference with the aluminum alloy matrix, and reduce galvanic corrosion. However, excessive addition of rare earth elements is easy to form a large amount of brittle Al-RE intermetallic compounds with the aluminum matrix, destroying the mechanical properties of the material and deteriorating the corrosion resistance. Therefore, the rare earth elements of the present invention include at least one of La, Ce, Y, Pm, Er, Nd, and Sm, and the rare earth element content ranges from 0.05% to 0.35%, preferably from 0.10% to 0.30%, and more preferably from 0.10% to 0.20%.

[0051] In some embodiments, the rare earth-containing corrosion-resistant deformable aluminum alloy includes the following components in mass fractions: Fe 0.05% to 0.20%, Si 0.05% to 0.15%, Mn 0.80% to 1.10%, Cr 0.01% to 0.15%, Ti 0.01% to 0.25%, rare earth 0.10% to 0.20%, and the remainder is Al and impurity elements, and the total mass percentage of the impurity elements is not more than 0.20%.

[0052] The following embodiment also provides a method for preparing a rare earth-containing corrosion-resistant deformable aluminum alloy, which is used to prepare the above rare earth-containing corrosion-resistant deformable aluminum alloy, comprising the following steps:

[0053] Step S100, providing prefabricated raw materials of pure aluminum ingots, aluminum-M master alloys, aluminum-rare earth master alloys, refining agents and refiners, where M includes at least one of Fe, Si, Mn, Ti and Zr, and the mass proportion of each element in the prefabricated raw materials is as follows: Fe 0.05% to 0.30%, Si 0.05% to 0.25%, Mn 0.80% to 1.6%, Cr 0.01% to 0.20%, Ti 0.01% to 0.30%, rare earth 0.05% to 0.35%, and the remainder is Al and impurity elements, and the total mass percentage of the impurity elements is not more than 0.20%.

[0054] Step S200: adding pure aluminum ingots into a smelting furnace and performing a first stage hot melting treatment to obtain an aluminum melt.

[0055] Step S300: adding aluminum-M master alloy to aluminum melt, performing second stage hot melting treatment, and obtaining aluminum alloy melt.

[0056] Step S400: adding aluminum-rare earth master alloy to the aluminum alloy melt, performing a third stage hot melt treatment, and obtaining a rare earth-containing aluminum alloy melt.

[0057] Step S500: adding a refining agent to the rare earth-containing aluminum alloy melt to perform a refining treatment to obtain a refined aluminum alloy melt.

[0058] Step S600: adding a rare earth composite refiner to the refined aluminum alloy melt to perform a refinement treatment to obtain a refined aluminum alloy melt.

[0059] Step S700: Casting and homogenizing the refined aluminum alloy melt in sequence to obtain a rare earth-containing corrosion-resistant deformable aluminum alloy bar or plate.

[0060] In some embodiments, the preparation method of the corrosion-resistant deformation aluminum alloy containing rare earths selects to use aluminum-M master alloy, aluminum-rare earth master alloy and other master alloys to add each component to a pure aluminum ingot for hot melting, so as to make the various components in the aluminum alloy dissolve more evenly. In addition, the aluminum-M master alloy is first dissolved in the pure aluminum melt, and then the aluminum-rare earth master alloy is added, so that the rare earth elements can better play the role of reducing non-metallic inclusions in the aluminum alloy, degassing, reducing casting defects and refining grains.

[0061] In some embodiments, the aluminum-M master alloy includes at least one of an aluminum-manganese master alloy, an aluminum-chromium master alloy, an aluminum-iron master alloy, an aluminum-silicon master alloy, and an aluminum-titanium master alloy.

[0062] In some embodiments, the aluminum-rare earth master alloy includes at least one of an aluminum-lanthanum master alloy, an aluminum-cerium master alloy, an aluminum-yttrium master alloy, an aluminum-praseodymium master alloy, an aluminum-erbium master alloy, an aluminum-neodymium master alloy, and an aluminum-samarium master alloy.

[0063] In some embodiments, before the first stage hot melt treatment, the process further includes: preheating the pure aluminum ingot, aluminum-M master alloy, aluminum-rare earth master alloy and refiner, so as to reduce the temperature difference between the materials and improve the smelting efficiency when the master alloys are gradually added. The preheating temperature is T 0 , 180℃≤T 0 ≤220℃, for example, T 0 The temperature may be 180°C, 190°C, 200°C, 210°C, 220°C or any range thereof. The preheating time is t 0 , 1h≤t 0 ≤5h, for example, t 0 It can be 1h, 2h, 3h, 4h, 5h or any range thereof.

[0064] In some embodiments, in the first stage of hot melting treatment, the temperature of the aluminum melt obtained by hot melting the pure aluminum ingot is T1, and T1 satisfies: 720℃≤T 1 ≤750℃, for example, T 1 The temperature may be 720°C, 730°C, 740°C, 750°C or any range thereof.

[0065] In some embodiments, in the second stage of hot melting treatment, an aluminum-M master alloy is added to the aluminum melt, and the temperature of the aluminum alloy melt obtained by hot melting is T 2 , T 2 Meet: 720℃≤T 2 ≤750℃, for example, T 2 The temperature may be 720°C, 730°C, 740°C, 750°C or any range thereof.

[0066] In some embodiments, in the third stage of hot melt treatment, an aluminum-rare earth master alloy is added to the aluminum alloy melt, and the temperature of the rare earth-containing aluminum alloy melt obtained is T 3 , T 3 Meet: 700℃≤T 3 ≤730℃, for example, T 3 The temperature may be 700°C, 705°C, 710°C, 720°C, 730°C or any range thereof.

[0067] Among them, T 1 ≤T 2 >T 3In this way, in the second stage of hot melt treatment, the aluminum-M master alloy is hot-melted at a higher temperature, and the aluminum-rare earth master alloy is added at a higher temperature, so that the rare earth elements and other alloying elements are more likely to react to form stable intermetallic compounds, promote the homogenization and alloying of the alloy, and help improve the uniformity and stability of the alloy.

[0068] After the third stage of hot melting treatment, refining treatment is performed; in some embodiments, the refining agent includes KCl, NaCl, Na 3 AlF 6 、Na 2 SiF 6 , CaF 2 , C 2 Cl 6 The refining agent is mainly used to remove the mixed hydrogen element, play a degassing role, reduce the porosity and porosity of the obtained rare earth-containing corrosion-resistant deformation aluminum alloy, and remove non-metallic inclusions to purify the aluminum alloy. Specifically, the refining treatment includes: a Temperature conditions, adding refining agent to the rare earth aluminum alloy melt, refining first time t m , and let stand for a second time t n After that, the slag is removed to obtain the refined aluminum alloy melt; 710℃≤T a ≤740℃,0.1h≤t m ≤0.25h, 0.15h≤t n ≤0.35h. Slag removal during the refining process is to remove the non-metallic compounds formed in the melt during the standing process, effectively purify the metal, and improve the quality and purity of the metal.

[0069] After the refining treatment, a refinement treatment is performed; in some embodiments, the refiner includes at least one of an aluminum-titanium-boron master alloy, an aluminum-titanium master alloy, and an aluminum-titanium-boron-rare earth master alloy, and the refiner is used to limit the growth of grains to form a fine and uniform grain structure, thereby improving the corrosion resistance of the aluminum alloy. Specifically, the refinement treatment includes: b Temperature conditions, add refiner to the refined aluminum alloy melt, stir and mix evenly, refine for a third time t h , after slag removal, the aluminum alloy melt after refinement treatment is obtained; among which, 700℃≤T b ≤740℃,0.15h≤t h ≤0.5h. The slag removal during the refinement process means removing the lumps condensed on the surface of the liquid during the refinement process.

[0070] The temperature of the aluminum alloy melt after refinement treatment is regulated to T c After casting, aluminum alloy bars are cast, 700℃≤Tc ≤720℃.

[0071] After the casting process is completed, the aluminum alloy bar is homogenized at a temperature of T j , 580℃≤T j ≤620℃, for example, T j The temperature may be 580°C, 590°C, 600°C, 610°C, 620°C or any range thereof; the holding time for homogenization treatment is t j , 10h≤t j ≤14h, for example, t j The time can be 10 hours, 11 hours, 12 hours, 13 hours, 14 hours or any range of the above two hours. After homogenization, the aluminum alloy ingot is preheated and then deformed by heat exchange round tube extrusion, microchannel flat tube extrusion and aluminum foil rolling.

[0072] The corrosion resistance test method of the aluminum alloy in the following examples and comparative examples is as follows: After exposure to the cyclic acidic seawater test (SWAAT) of ASTM G85 standard for 21 days, the corrosion depth of the aluminum alloy is measured.

[0073] Example 1

[0074] Step S111, providing prefabricated raw materials including pure aluminum ingot (purity 99.75), aluminum-M master alloy (including aluminum-manganese master alloy, aluminum-chromium master alloy), aluminum-rare earth master alloy (including aluminum-cerium master alloy, aluminum-lanthanum master alloy), refiner (including aluminum-titanium-boron master alloy) and refining agent, and preheating the above materials except the refining agent, the preheating temperature T 0 The temperature is 200℃, and the preheating time is t 0 The temperature is 2h, and refining agent (including hexachloroethane) is provided for standby use.

[0075] The mass proportions of the elements in the prefabricated raw materials are as follows: Fe 0.2%; Si 0.15%; Mn 0.92%; Ti 0.025%; Cr 0.1%, rare earth 0.1%; and the balance is Al.

[0076] Step S112: Add the pure aluminum ingot into the smelting furnace and perform the first stage of hot melting treatment to obtain aluminum melt. The temperature of the aluminum melt is T 1 It is 740~750℃.

[0077] Step S113, adding aluminum-M master alloy (including aluminum-manganese master alloy and aluminum-chromium master alloy) to the aluminum melt, stirring and mixing evenly, and performing the second stage hot melting treatment to obtain an aluminum alloy melt. The temperature of the aluminum alloy melt is T 2 It is 720~730℃.

[0078] Step S114: adding aluminum-rare earth master alloy (including aluminum-cerium master alloy and aluminum-lanthanum master alloy) to the aluminum alloy melt, and performing the third stage hot melt treatment to obtain a rare earth aluminum alloy melt. The temperature of the rare earth aluminum alloy melt is T 3 It is 710~730℃.

[0079] Step S115: a Temperature conditions, adding refining agent to the rare earth aluminum alloy melt, refining treatment, refining first time t m , and let stand for a second time t n After that, the refined aluminum alloy melt is obtained after slag removal, T a =720℃,t m =0.15h,t n =0.25h.

[0080] Step S116: b Temperature conditions, adding a refiner (aluminum-titanium-boron master alloy) to the refined aluminum alloy melt for refinement treatment, and the refinement third time t h , after slag removal, the aluminum alloy melt is obtained after refinement treatment, T b =720℃,t h =0.25h.

[0081] Step S117: Regulating the temperature of the aluminum alloy melt after refinement to T c After casting, aluminum alloy bars are cast. c =710℃.

[0082] Step S118: After the casting process is completed, the aluminum alloy bar is homogenized at a temperature T j The temperature is 580℃, and the homogenization holding time is t j After homogenization, the pre-cooled aluminum alloy short bars are water-cooled and cut into preset sizes to obtain pre-cooled aluminum alloy short bars.

[0083] Step S119: heat the pre-cooled aluminum alloy short bar to a temperature T e , and keep warm for time t e , obtain the preheated aluminum alloy short bar, T e =510℃,t e =1h.

[0084] Step S120: Use a horizontal extruder to perform hot extrusion on the preheated aluminum alloy short bar. The die temperature for the extrusion process is T i The temperature is 500°C, the extrusion speed Vi is 20m / min, the extrusion ratio is 200:1, and the profile is quickly cooled after extrusion to obtain a corrosion-resistant deformed aluminum alloy heat exchange round tube containing rare earth.

[0085] According to tests, the corrosion depth of the rare earth-containing corrosion-resistant deformed aluminum alloy heat exchange circular tube obtained in this embodiment is 150 μm after being exposed to the cyclic acidic seawater test (SWAAT) of ASTM G85 standard for 21 days.

[0086] Example 2

[0087] Step S121, providing prefabricated raw materials including pure aluminum ingot (purity 99.75), aluminum-M master alloy (including aluminum-manganese master alloy, aluminum-chromium master alloy), aluminum-rare earth master alloy (including aluminum-lanthanum-cerium mixed rare earth master alloy), refiner (including aluminum-titanium-boron master alloy) and refining agent, and preheating the above materials except the refining agent, the preheating temperature T 0 The temperature is 200℃, and the preheating time is t 0 The temperature is 2h, and refining agent (including hexachloroethane) is provided for standby use.

[0088] The mass proportions of the elements in the prefabricated raw materials are as follows: Fe 0.2%; Si 0.15%; Mn 0.92%; Ti 0.025%; Cr 0.1%, rare earth 0.1%; and the balance is Al.

[0089] Step S122: Add the pure aluminum ingot into the smelting furnace and perform the first stage of hot melting treatment to obtain aluminum melt. The temperature of the aluminum melt is T 1 It is 740~750℃.

[0090] Step S123, adding aluminum-M master alloy (including aluminum-manganese master alloy and aluminum-chromium master alloy) to the aluminum melt, stirring and mixing evenly, and performing the second stage hot melting treatment to obtain an aluminum alloy melt. The temperature of the aluminum alloy melt is T 2 It is 720~730℃.

[0091] Step S124, adding aluminum-rare earth master alloy (including aluminum-lanthanum-cerium mixed rare earth master alloy) to the aluminum alloy melt, and performing the third stage hot melt treatment to obtain a rare earth aluminum alloy melt. The temperature of the rare earth aluminum alloy melt is T 3 It is 710~730℃.

[0092] Step S125: a Temperature conditions, adding refining agent to the rare earth aluminum alloy melt, refining treatment, refining first time t m , and let stand for a second time t n After that, the refined aluminum alloy melt is obtained after slag removal, T a =720℃,t m =0.15h,t n =0.25h.

[0093] Step S126: b Temperature conditions, adding a refiner (aluminum-titanium-boron master alloy) to the refined aluminum alloy melt for refinement treatment, and the refinement third time t h , after slag removal, the aluminum alloy melt is obtained after refinement treatment, T b =720℃,t h =0.25h.

[0094] Step S127: Regulating the temperature of the aluminum alloy melt after refinement to T c After casting, aluminum alloy bars are cast. c =710℃.

[0095] Step S128: After the casting process is completed, the aluminum alloy bar is homogenized at a temperature T j The temperature is 600℃, and the homogenization holding time is t j After homogenization, water cooling is performed and the pre-cooled aluminum alloy short bars are cut according to the preset size.

[0096] Step S129: heat the pre-cooled aluminum alloy short bar to a temperature T e , and keep warm for time t e , obtain the preheated aluminum alloy short bar, T e =530℃,t e =1h.

[0097] Step S130: Use a horizontal extruder to perform hot extrusion on the preheated aluminum alloy short bar. The die temperature for the extrusion process is T i is 500℃, extrusion speed V i The speed is 20 m / min, the extrusion ratio is 400:1, and the profile is rapidly cooled after extrusion to obtain a corrosion-resistant deformable aluminum alloy microchannel flat tube containing rare earth.

[0098] According to tests, the corrosion depth of the rare earth-containing corrosion-resistant deformed aluminum alloy obtained in this embodiment is 180 μm after being exposed to the cyclic acidic seawater test (SWAAT) of ASTM G85 standard for 21 days.

[0099] Example 3

[0100] Step S121, providing prefabricated raw materials including pure aluminum ingot (purity 99.75), aluminum-M master alloy (including aluminum-manganese master alloy, aluminum-chromium master alloy), aluminum-rare earth master alloy (including aluminum-lanthanum-cerium mixed rare earth master alloy), refiner (including aluminum-titanium-boron master alloy) and refining agent, and preheating the above materials except the refining agent, the preheating temperature T 0 The temperature is 200℃, and the preheating time is t 0The temperature is 2h, and refining agent (including hexachloroethane) is provided for standby use.

[0101] The mass proportions of the elements in the prefabricated raw materials are as follows: Fe 0.2%; Si 0.15%; Mn 0.92%; Ti 0.05%; Cr 0.15%, rare earth 0.15%; and the balance is Al.

[0102] Step S122: Add the pure aluminum ingot into the smelting furnace and perform the first stage of hot melting treatment to obtain aluminum melt. The temperature of the aluminum melt is T 1 It is 740~750℃.

[0103] Step S123, adding aluminum-M master alloy (including aluminum-manganese master alloy and aluminum-chromium master alloy) to the aluminum melt, stirring and mixing evenly, and performing the second stage hot melting treatment to obtain an aluminum alloy melt. The temperature of the aluminum alloy melt is T 2 It is 720~730℃.

[0104] Step S124, adding aluminum-rare earth master alloy (including aluminum-lanthanum-cerium mixed rare earth master alloy) to the aluminum alloy melt, and performing the third stage hot melt treatment to obtain a rare earth aluminum alloy melt. The temperature of the rare earth aluminum alloy melt is T 3 It is 710~730℃.

[0105] Step S125: adding a refining agent to the rare earth aluminum alloy melt at a temperature of Ta to perform a refining treatment for a first refining time t m , and let stand for a second time t n After that, the refined aluminum alloy melt is obtained after slag removal, T a =720℃,t m =0.15h,t n =0.25h.

[0106] Step S126: b Temperature conditions, adding a refiner (aluminum-titanium-boron master alloy) to the refined aluminum alloy melt for refinement treatment, and the refinement third time t h , after slag removal, the aluminum alloy melt is obtained after refinement treatment, T b =720℃,t h =0.25h.

[0107] Step S127, adjusting the temperature of the aluminum alloy melt after refinement to T c After casting, aluminum alloy plates are cast. c =710℃.

[0108] Step S128: After the casting process is completed, the aluminum alloy plate is homogenized at a temperature T jThe temperature is 600℃, and the homogenization holding time is t j After homogenization, the aluminum alloy sheet is water-cooled and cut into pre-set sizes to obtain pre-cooled aluminum alloy sheets.

[0109] Step S129: heat the pre-cooled aluminum alloy short bar to a temperature T e , and keep warm for time t e , obtain the preheated aluminum alloy short bar, T e =530℃,t e =1h.

[0110] Step S130: hot rolling the preheated aluminum alloy plate using a rolling mill. The plate is first hot rolled into a 4 mm plate, then cold rolled to 0.40 mm, annealed at 400° C. for 2 h, and then cold rolled to a foil with a thickness of 0.20 mm.

[0111] According to tests, the corrosion depth of the rare earth-containing corrosion-resistant deformable aluminum alloy foil obtained in this embodiment is 170 μm after being exposed to the cyclic acidic seawater test (SWAAT) of ASTM G85 standard for 21 days.

[0112] The difference between the rare earth-containing aluminum alloy preparation methods in each embodiment and comparative example mainly lies in the differences in the parameters of the aluminum alloy raw materials, homogenization treatment, and heating treatment used. Comparative Examples 1, 2, and 3 are respectively heat exchange circular tubes, microchannel flat tubes, and aluminum foils made of 3003 aluminum alloy, and the specifications are consistent with the embodiments.

[0113] Table 1

[0114]

[0115] As shown in Table 1, by adding rare earth elements and adjusting the proportion of each component of the aluminum alloy within a suitable range, the processed rare earth-containing corrosion-resistant deformable aluminum alloy has good mechanical properties, and the tensile strength, yield strength and elongation all meet the performance requirements of the 3003 type aluminum alloy in the prior art. In addition, the cyclic acidic seawater test found that the corrosion depth of the rare earth-containing corrosion-resistant deformable aluminum alloy prepared in the embodiment is much smaller than the corrosion depth of the 3003 series aluminum alloy, and has good corrosion resistance.

[0116] Scanning electron microscope to detect the microstructure of aluminum alloy Figure 1 and 2 As shown, Figure 1 The microstructure of the rare earth-containing corrosion-resistant deformable aluminum alloy prepared in Example 3 is shown. Figure 2 The microstructure of the 3003 series aluminum alloy prepared in Comparative Example 1 is shown. Figure 1 and Figure 2The light-colored area pointed by the middle arrow s is the location of the intermetallic compounds (second phase) distributed between the aluminum alloy structures. It can be seen that the intermetallic compounds of the 3003 aluminum alloy prepared in Comparative Example 1 are in the shape of long strips and have poor distribution uniformity. The intermetallic compounds of the rare earth-containing corrosion-resistant deformable aluminum alloy prepared in Example 3 are all granular, small in size and evenly distributed, and have good corrosion resistance.

[0117] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A corrosion-resistant deformable aluminum alloy containing rare earth, characterized in that: The invention comprises the following components in terms of mass percentage: Fe 0.05% to 0.30%, Si 0.05% to 0.25%, Mn 0.80% to 1.6%, Cr 0.01% to 0.20%, Ti 0.01% to 0.30%, rare earth 0.05% to 0.35%, and the remainder is Al and impurity elements, and the total mass percentage of the impurity elements is not more than 0.20%.

2. The corrosion-resistant deformable aluminum alloy containing rare earth according to claim 1, characterized in that: The rare earth includes at least one of La, Ce, Y, Pm, Er, Nd and Sm, and the total mass percentage of the rare earth is 0.10% to 0.25%.

3. The corrosion-resistant deformable aluminum alloy containing rare earth according to claim 1 or 2, characterized in that: The rare earth-containing corrosion-resistant deformable aluminum alloy includes the following components in terms of mass percentage: Fe 0.05%-0.20%, Si 0.05%-0.15%, Mn 0.80%-1.10%, Cr 0.01%-0.20%, Ti 0.01%-0.25%, rare earth 0.10%-0.25%, and the remainder is Al and impurity elements, and the total mass percentage of the impurity elements is not more than 0.20%.

4. The method for preparing the rare earth-containing corrosion-resistant deformable aluminum alloy according to any one of claims 1 to 3, characterized in that: The following steps are involved: (1) providing a prefabricated raw material of pure aluminum ingot, aluminum-M master alloy, aluminum-rare earth master alloy, refining agent and rare earth composite refiner, wherein M comprises at least one of Fe, Si, Mn, Cr and Ti, and the mass percentage of each element in the prefabricated raw material satisfies the following: Fe 0.05% to 0.30%, Si 0.05% to 0.25%, Mn 0.80% to 1.6%, Cr 0.01% to 0.20%, Ti 0.01% to 0.30%, rare earth 0.05% to 0.35%, and the remainder is Al and impurity elements, and the total mass percentage of the impurity elements is not more than 0.20%; (2) adding a pure aluminum ingot into a smelting furnace and performing a first-stage hot-melt treatment to obtain an aluminum melt; (3) adding an aluminum-M master alloy to the aluminum melt, performing a second stage hot melt treatment, and obtaining an aluminum alloy melt; (4) adding an aluminum-rare earth master alloy to the aluminum alloy melt, performing a third stage hot melt treatment, and obtaining a rare earth-containing aluminum alloy melt; (5) adding a refining agent to the rare earth-containing aluminum alloy melt to perform a refining treatment to obtain a refined aluminum alloy melt; (6) adding a rare earth composite refiner to the refined aluminum alloy melt to perform a refinement treatment to obtain a refined aluminum alloy melt; (7) The refined aluminum alloy melt is cast and homogenized in sequence to obtain a rare earth-containing corrosion-resistant deformable aluminum alloy rod or plate.

5. The method for preparing the rare earth-containing corrosion-resistant deformable aluminum alloy according to claim 4, characterized in that: The aluminum-M master alloy includes at least one of an aluminum-iron master alloy, an aluminum-silicon master alloy, an aluminum-manganese master alloy, an aluminum-chromium master alloy, and an aluminum-titanium master alloy; and / or the aluminum-rare earth master alloy includes at least one of an aluminum-lanthanum master alloy, an aluminum-cerium master alloy, an aluminum-yttrium master alloy, an aluminum-praseodymium master alloy, an aluminum-erbium master alloy, an aluminum-neodymium master alloy, and an aluminum-samarium master alloy; and / or the rare earth composite refiner is an aluminum-titanium-boron-rare earth composite refiner, wherein the rare earth is at least one of lanthanum, cerium, yttrium, praseodymium, erbium, neodymium and samarium; And / or the refining agent includes at least one of KCl, NaCl, Na3AlF6, Na2SiF6, CaF2, and C2Cl6.

6. The method for preparing the rare earth-containing corrosion-resistant deformable aluminum alloy according to claim 4, characterized in that: Before the first stage hot melt treatment, the process also includes: preheating the pure aluminum ingot, aluminum-M master alloy, aluminum-rare earth master alloy and rare earth composite refiner, wherein the preheating temperature is T0 and the time is t0, wherein 180°C≤T0≤220°C and 1h≤t0≤5h.

7. The method for preparing the rare earth-containing corrosion-resistant deformable aluminum alloy according to claim 4, characterized in that: In step (2), the temperature of the aluminum melt is T1, and T1 satisfies: 720°C≤T1≤750°C; And / or in step (3), the temperature of the aluminum alloy melt is T2, and T2 satisfies: 720°C≤T2≤750°C; And / or in step (4), the temperature of the rare earth-containing aluminum alloy melt is T3, and T3 satisfies: 700°C≤T3≤730°C.

8. The method for preparing the rare earth-containing corrosion-resistant deformable aluminum alloy according to claim 4, characterized in that: In step (5), the refining process comprises: a temperature conditions, adding the refining agent to the rare earth-containing aluminum alloy melt, refining for a first time t m , and let stand for a second time t n , slag removal, obtain the refined aluminum alloy melt; 710℃≤T a ≤740℃,0.1h≤t m ≤0.25h, 0.15h≤t n ≤0.35h; And / or in step (6), the refinement process includes: b temperature conditions, adding a refiner to the refined aluminum alloy melt, refining for a third time t h , slag removal, obtain the aluminum alloy melt after refinement treatment; 700℃≤T b ≤740℃,0.15h≤t h ≤0.5h; And / or in step (7), the temperature of the homogenization treatment is T j , time is t j , 580℃≤T j ≤620℃,10h≤t j ≤14h.

9. Use of the rare earth-containing corrosion-resistant deformable aluminum alloy according to any one of claims 1 to 3 in the preparation of heat exchanger parts, wherein the heat exchanger parts include heat exchange circular tubes, microchannel flat tubes and aluminum foil.

10. The use according to claim 9, characterized in that: The tensile strength Rm of the aluminum alloy heat exchange round tube satisfies: 100MPa≤Rm≤130MPa, the yield strength Rp0.2 satisfies: 40MPa≤Rp0.2≤55MPa, and the elongation 40%≤A≤55%; And / or the tensile strength Rm of the aluminum alloy microchannel flat tube satisfies: 90MPa≤Rm≤108MPa, the yield strength Rp0.2 satisfies: 35MPa≤Rp0.2≤50MPa, and the elongation 45%≤A≤55%; And / or the tensile strength Rm of the aluminum foil satisfies: 85MPa≤Rm≤135MPa, the yield strength Rp0.2 satisfies: 35MPa≤Rp0.2≤55MPa, and the elongation 35%≤A≤45%.

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