Aluminum alloy suitable for brazing and high melting point die casting without heat treatment and preparation method thereof

Abstract

The present invention provides a heat-treatment-free high-melting-point die-casting aluminum alloy suitable for brazing and a preparation method, relating to the field of aluminum alloys. The mass percentages of alloy components are as follows: Si 0.05-0.7%, Mn 1.3-3.4%, Fe 0.7-2.4%, Mg 0.25-0.9%, Ti 0.06-0.28%, V 0.005-0.16%, Zn 0.5-3.5%, Hf 0.003-0.016%, RE 0.01-2.5%, where RE includes at least one of La / Ce / Sc, and the balance is Al and inevitable impurities, with the total amount of impurities ≤ 0.2%; and 0.2 < Fe:Mn < 2, 0.05 < Si:Mg < 3, 0.01 < RE:Mn < 2, 0.1 < Zn:Mn < 2.7. This aluminum alloy can meet the requirements of high-pressure die-casting and brazing simultaneously, solve the brazing problem of traditional die-casting aluminum alloys, and greatly improve production efficiency.

Description

Technical Field

[0001] The invention relates to the technical field of aluminum alloy materials, and in particular to a heat-treatment-free high-melting-point die-casting aluminum alloy suitable for brazing and a preparation method thereof. Background Art

[0002] In recent years, die-cast aluminum alloy materials have been widely used in the automotive industry. Some automotive parts have long been generally made of high vacuum die-casting technology, but they usually cannot meet welding requirements when connected. Due to the characteristics of cast aluminum alloys themselves, welding between dissimilar aluminum alloys (such as deformed aluminum alloys) will encounter problems. The weldability depends on the differences in physical properties, chemical properties, metallurgical and mechanical properties between the two parent materials. Therefore, the development of new parent materials, welding wires and welding processes is an urgent problem to be solved in the automotive industry.

[0003] Brazing is a welding technology that uses a brazing filler metal with a lower melting point than the aluminum alloy base material, and an operating temperature that is lower than the base material solidus and higher than the brazing filler metal liquidus, to connect the base materials together through the molten brazing filler metal. Currently, the 3000 series alloy (such as AA3003) is a traditional aluminum alloy for automotive heat exchangers. It can be used in almost all brazing methods, while the single 5000 series and 6000 series are generally used for vacuum brazing. The automotive industry is developing in the direction of lightweighting, and aluminum brazing methods have become a key technology.

[0004] The most commonly used process at present is to weld aluminum profiles and aluminum plates after mechanical processing, but this method is time-consuming and costly, and is not an ideal production process. Conventional cast aluminum alloys are mainly aluminum-silicon alloys, which have good casting formability but low melting point (<590℃). The temperature during high-temperature brazing is high (610℃). After soaking for a period of time, the material will soften and easily produce pore defects, making it impossible to produce qualified products, and therefore cannot meet the use requirements. Summary of the invention

[0005] The purpose of the present invention is to provide a high-melting-point die-casting aluminum alloy suitable for brazing and free of heat treatment and a preparation method thereof, so as to solve the problems existing in the above-mentioned prior art.

[0006] The alloy material of the present invention redesigns and regulates the composition on the basis of Al-Mn alloy, and achieves good brazing and castability through optimization of alloy composition. Al-Mn alloy is a commonly used deformed aluminum alloy, which has the advantages of good corrosion resistance, high specific strength, good thermal conductivity, etc. Mn can prevent the recrystallization process of aluminum and its alloys, increase the recrystallization temperature, and significantly refine the grains. It can be seen from the equilibrium phase diagram of Al-Mn alloy that the eutectic point at 658°C is 1.82%, forming a eutectic intermetallic compound Al6Mn phase as the main phase. A certain content of Mn can ensure that the alloy has good fluidity and is suitable for die casting, and the melting point of the alloy is higher than the temperature required for brazing and is suitable for brazing.

[0007] Adding Fe to the alloy can reduce the solubility of Mn in aluminum, increase the precipitation of Mn to reduce the segregation of Mn in aluminum, but the Fe content cannot be too much, which is easy to form a coarse Al6 (FeMn) phase, which is a hard and brittle phase distributed in the organization in large flakes, reducing the plasticity and strength of the alloy. Fe can also improve the fluidity of the alloy and facilitate demolding during die casting, which is beneficial to the die casting process.

[0008] Adding Si to the system of the present invention has little effect on improving fluidity, but too much Si can easily form intermetallic compounds such as Al 15 (FeMn)3Si2 phase is a harmful phase that will significantly reduce the solidus temperature, thus failing to meet the brazing requirements. Therefore, the present invention strictly controls the Si content below 0.7%, and the Fe and Si contents within a certain range will form a large number of finely dispersed second phases, which can significantly improve the strength and toughness of the alloy.

[0009] The addition of Zn to the alloy can significantly improve the fluidity of the alloy, and it can easily form a MgZn phase with Mg, thereby increasing the strength of the alloy and improving the mechanical properties of the alloy.

[0010] Mg is added to the alloy to form a Mg2Si reinforcement phase, which plays a role in solid solution strengthening and improves the yield strength of the alloy, but excessive addition will reduce brazing properties. On the one hand, a large Mg content will reduce the melting point of the alloy, and on the other hand, Mg has a tendency to react chemically with the brazing material, which can easily affect the welding quality. Therefore, Mg should not be added excessively in the alloy. Ti can effectively refine the grains and improve the strength and toughness of the alloy.

[0011] Adding trace element V can improve the tensile strength and elongation of aluminum alloy. V element will precipitate spherical AlFeSi(Mn+V) phase in the matrix, effectively reducing the lamellar iron-rich phase in the matrix, which is beneficial to improving the toughness of aluminum alloy. Trace Hf can form a high-temperature stable compound Al3Hf with aluminum, which can better improve the heat resistance of the alloy, and as a nucleation particle, it improves the heterogeneous nucleation ability of the alloy, so that the alloy structure is refined to a certain extent.

[0012] RE rare earth elements have an obvious strengthening effect in aluminum alloys, mainly including fine grain strengthening, limited solid solution strengthening and second phase strengthening of rare earth compounds. At the same time, it can improve the fluidity of the alloy, reduce the hydrogen content in the aluminum alloy liquid, and reduce the probability of gas impurity defects, playing a good role in purifying the aluminum liquid. Die casting itself is likely to make the casting contain gas, and the brazing process requires a high gas content in a vacuum state. Adding rare earth elements can play an obvious improvement role.

[0013] The present invention provides the following technical solutions:

[0014] One of the technical solutions of the present invention: Provide a die-casting aluminum alloy suitable for brazing, and the mass percentage content of the alloy components is as follows:

[0015] Si: 0.05 - 0.7 wt.%, Mn: 1.3 - 3.4 wt.%, Fe: 0.7 - 2.4 wt.%, Mg: 0.25 - 0.9 wt.%, Ti: 0.06 - 0.28 wt.%, V: 0.005 - 0.16 wt.%, Zn: 0.5 - 3.5 wt.%, Hf: 0.003 - 0.016 wt.%, RE: 0.01 - 2.5 wt.%, RE includes at least one or more of La, Ce and Sc, and the balance is Al and unavoidable impurities, where the total amount of impurities ≤ 0.2%;

[0016] Among them, the mass percentage content of Fe and Mn satisfies: 0.2 < Fe:Mn < 2; the mass percentage content of Si and Mg satisfies: 0.05 < Si:Mg < 3; the mass percentage content of RE and Mn satisfies: 0.01 < RE:Mn < 2; the mass percentage content of Zn and Mn satisfies: 0.1 < Zn:Mn < 2.7.

[0017] As a further preference of the present invention, the mass percentage content of the die-casting aluminum alloy suitable for brazing is as follows:

[0018] Si: 0.05 - 0.2 wt.%, Mn: 2.7 - 3.4 wt.%, Fe: 0.7 - 1.0 wt.%, Mg: 0.7 - 0.9 wt.%, Ti: 0.06 - 0.28 wt.%, V: 0.005 - 0.16 wt.%, Zn: 0.5 - 1.5 wt.%, Hf: 0.003 - 0.016 wt.%, RE: 2.1 - 2.5 wt.%, RE includes at least one or more of La, Ce and Sc, and the balance is Al and unavoidable impurities, where the total amount of impurities ≤ 0.2%;

[0019] Among them, the mass percentage contents of Fe and Mn satisfy: 0.2 < Fe:Mn < 2; the mass percentage contents of Si and Mg satisfy: 0.05 < Si:Mg < 3; the mass percentage contents of RE and Mn satisfy: 0.01 < RE:Mn < 2; the mass percentage contents of Zn and Mn satisfy: 0.1 < Zn:Mn < 2.7.

[0020] As a further preference of the present invention, the mass percentage contents of the aluminum alloy for die casting suitable for brazing are as follows:

[0021] Si: 0.21 - 0.5 wt.%, Mn: 2.0 - 2.6 wt.%, Fe: 1.1 - 2.0 wt.%, Mg: 0.36 - 0.6 wt.%, Ti: 0.06 - 0.28 wt.%, V: 0.005 - 0.16 wt.%, Zn: 1.6 - 3.0 wt.%, Hf: 0.003 - 0.016 wt.%, RE: 1.6 - 2.0 wt.%, RE includes at least one or more of La, Ce, and Sc, and the balance is Al and inevitable impurities, where the total amount of impurities ≤ 0.2%;

[0022] Among them, the mass percentage contents of Fe and Mn satisfy: 0.2 < Fe:Mn < 2; the mass percentage contents of Si and Mg satisfy: 0.05 < Si:Mg < 3; the mass percentage contents of RE and Mn satisfy: 0.01 < RE:Mn < 2; the mass percentage contents of Zn and Mn satisfy: 0.1 < Zn:Mn < 2.7.

[0023] As a further preference of the present invention, the mass percentage contents of the aluminum alloy for die casting suitable for brazing are as follows:

[0024] Si: 0.51 - 0.7 wt.%, Mn: 1.3 - 1.9 wt.%, Fe: 2.1 - 2.4 wt.%, Mg: 0.25 - 0.35 wt.%, Ti: 0.06 - 0.28 wt.%, V: 0.005 - 0.16 wt.%, Zn: 3.1 - 3.5 wt.%, Hf: 0.003 - 0.016 wt.%, RE: 0.01 - 1.5 wt.%, RE includes at least one or more of La, Ce, and Sc, and the balance is Al and inevitable impurities, where the total amount of impurities ≤ 0.2%;

[0025] Among them, the mass percentage contents of Fe and Mn satisfy: 0.2 < Fe:Mn < 2; the mass percentage contents of Si and Mg satisfy: 0.05 < Si:Mg < 3; the mass percentage contents of RE and Mn satisfy: 0.01 < RE:Mn < 2; the mass percentage contents of Zn and Mn satisfy: 0.1 < Zn:Mn < 2.7.

[0026] As a further preferred embodiment of the present invention, the mass percentage content of the die-casting aluminum alloy components suitable for brazing is as follows:

[0027] Si: 0.05wt.%, Mn: 3.4wt.%, Fe: 1.0wt.%, Mg: 0.9wt.%, Ti: 0.06wt.%, V: 0.16wt.%, Zn: 1.5wt.%, Hf: 0.015wt.%, RE: 2.5wt.%, RE includes at least one or more of La, Ce and Sc, and the balance is Al and unavoidable impurities, wherein the total amount of impurities is ≤0.2%.

[0028] As a further preferred embodiment of the present invention, the mass percentage content of the die-casting aluminum alloy components suitable for brazing is as follows:

[0029] Si: 0.5wt.%, Mn: 2.0wt.%, Fe: 1.8wt.%, Mg: 0.36wt.%, Ti: 0.08wt.%, V: 0.13wt.%, Zn: 1.6wt.%, Hf: 0.013wt.%, RE: 2.0wt.%, RE includes at least one or more of La, Ce and Sc, and the balance is Al and unavoidable impurities, wherein the total amount of impurities is ≤0.2%.

[0030] As a further preferred embodiment of the present invention, the mass percentage content of the die-casting aluminum alloy components suitable for brazing is as follows:

[0031] Si: 0.7wt.%, Mn: 1.3wt.%, Fe: 2.2wt.%, Mg: 0.25wt.%, Ti: 0.12wt.%, V: 0.10wt.%, Zn: 3.3wt.%, Hf: 0.012wt.%, RE: 0.01wt.%, RE includes at least one or more of La, Ce and Sc, and the balance is Al and unavoidable impurities, wherein the total amount of impurities is ≤0.2%.

[0032] As a further preference of the present invention, the solidus temperature of the die-casting aluminum alloy suitable for brazing is ≥631.15°C (DSC curve analysis results show that the solidus temperature of the aluminum alloy is ≥631.15°C, which is higher than the temperature during vacuum brazing, and the alloy is suitable for brazing); the die-casting aluminum alloy suitable for brazing has a tensile strength of ≥262MPa, a yield strength of ≥144MPa, and an elongation of ≥11.2%.

[0033] In the present invention, the die-casting aluminum alloy suitable for brazing has a fluidity mold test result length of ≥1133 mm.

[0034] The second technical solution of the present invention is to provide a method for preparing the above-mentioned die-casting aluminum alloy suitable for brazing, comprising the following steps: melting the raw materials according to the alloy component ratio, then refining and exhausting the melt, obtaining an aluminum alloy ingot after pouring, and then die-casting the aluminum alloy ingot to obtain the die-casting brazed aluminum alloy.

[0035] As a further preferred embodiment of the present invention, the die-casting conditions are: die-casting pressure 400-550 bar, injection speed 4-6 m / s, vacuum degree <40 mbar, die-casting temperature 690-730°C, and mold temperature 200-230°C.

[0036] The more preferred preparation method of the present invention comprises the following steps:

[0037] 1) Raw material preheating: Prepare the materials according to the alloy composition ratio, preheat the raw materials to be melted to 200℃ and dry them.

[0038] 2) Alloy smelting: heat to 740-760°C, add pure aluminum, pure Zn, Al-Si master alloy, Al-Mn master alloy, Al-Fe master alloy, Al-Ti master alloy, Al-V master alloy, Al-Hf master alloy, RE rare earth into the furnace for melting, cool to 700-720°C after melting, add pure Mg, press it into the bottom of the crucible with a tool to prevent Mg from burning on the liquid surface to ensure complete melting.

[0039] 3) Refining and degassing: Keep the temperature at 720℃, use rotary spray degassing equipment, introduce nitrogen with refining agent powder into the melt for powder spray refining, the amount of refining agent added is 0.3-0.5%, the melt is refined and degassed for 8-10 minutes, and the scum on the liquid surface is scraped off and allowed to stand for 10 minutes.

[0040] 4) Pouring ingot: Cast a small sample for component analysis, and then cast it into ingot after the composition is qualified.

[0041] 5) Die-casting process: melt the above aluminum alloy ingots and perform high-pressure die-casting. The die-casting process adopts a die-casting pressure of 400-550 bar, an injection speed of 4-6 m / s, a vacuum degree of <40 mbar, a die-casting temperature of 690-730°C, and a mold temperature of 200-230°C.

[0042] The present invention discloses the following technical effects:

[0043] The aluminum alloy material of the present invention can simultaneously meet the requirements of high-pressure die-casting and high-temperature vacuum brazing, effectively solving the problem that traditional die-cast aluminum alloys cannot be brazed, and can be widely used in the automobile manufacturing industry to greatly improve production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0045] Figure 1 This is a scanning electron microscope (SEM) microstructure image of the alloy of Example 9 of the present invention.

[0046] Figure 2 This is a diagram showing the DSC curve analysis results of the alloy of Example 4 of the present invention.

[0047] Figure 3 This is a diagram showing the fluidity mold test results of the alloy of Example 1 of the present invention. DETAILED DESCRIPTION

[0048] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0049] It should be understood that the terms described in the present invention are only for describing a particular embodiment and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. The intermediate value in any stated value or stated range, and each smaller range between any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0050] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0051] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to those skilled in the art. The present invention description and examples are exemplary only.

[0052] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0053] Example 1

[0054] This embodiment relates to a heat-treatment-free aluminum alloy for die casting that can be brazed, and the mass percentages of its components are as follows:

[0055] Si: 0.05wt.%, Mn: 3.4wt.%, Fe: 1.0wt.%, Mg: 0.9wt.%, Ti: 0.06wt.%, V: 0.16wt.%, Zn: 1.5wt.%, Hf: 0.015wt.%, RE: 2.5wt.%, RE is a mixed rare earth of La and Ce, in which the mass ratio of La to Ce is 4:6, and the balance is Al and unavoidable impurities, among which the total amount of impurities is ≤0.2%.

[0056] The preparation method of the above aluminum alloy is as follows:

[0057] 1) Material preparation and preheating: Prepare the materials according to the alloy composition ratio, preheat the raw materials to be melted to 200℃ and dry them.

[0058] 2) Alloy smelting: heat to 740°C, add raw materials with calculated proportions into the furnace, including pure aluminum, pure Zn, Al-Si master alloy, Al-Mn master alloy, Al-Fe master alloy, Al-Ti master alloy, Al-V master alloy, Al-Hf master alloy, RE (La, Ce mixed rare earth) alloy for melting, wait for the above alloys to melt and cool to 720°C, add pure Mg, and press it into the bottom of the crucible with a tool to prevent Mg from burning on the liquid surface to ensure complete melting.

[0059] 3) Refining and degassing: keep the temperature at 720℃, add 0.5% by weight of refining agent into the aluminum liquid, use argon rotary powder spraying refining and degassing equipment to degas the melt, the degassing time is 10 minutes, scrape off the scum on the liquid surface and let it stand for 10 minutes.

[0060] 4) Pouring ingot: The casting sample is subjected to spectral composition analysis, and after the composition is qualified, it is cast into an ingot.

[0061] 5) Die-casting process: melt the above aluminum alloy ingots and then perform high-pressure die-casting. The above aluminum alloy ingots are melted and then perform high-pressure die-casting. The die-casting process adopts a die-casting pressure of 550 bar, an injection speed of 6 m / s, a vacuum degree of 25 mbar, a die-casting temperature of 710° C., and a mold temperature of 220° C.

[0062] 6) The die-casting mold is a flat mold and a mold for fluidity testing. The mechanical properties test is carried out by taking a tensile test piece from the die-cast flat mold casting body, and the fluidity is measured simultaneously. The flat mold body is sampled for SEM scanning electron microscopy analysis of the microstructure, and the solidus temperature is analyzed by DSC differential thermal scanner.

[0063] Example 2

[0064] This embodiment relates to a heat-treatment-free aluminum alloy for die casting that can be brazed, and the mass percentages of its components are as follows:

[0065] Si: 0.65wt.%, Mn: 1.9wt.%, Fe: 2.1wt.%, Mg: 0.35wt.%, Ti: 0.15wt.%, V: 0.015wt.%, Zn: 3.1wt.%, Hf: 0.012wt.%, RE: 1.5wt.%, RE is a mixed rare earth of La and Sc, in which the mass ratio of La to Sc is 5:5, and the balance is Al and unavoidable impurities, among which the total amount of impurities is ≤0.2%.

[0066] The preparation method of the above aluminum alloy is as follows:

[0067] 1) Material preparation and preheating: Prepare the materials according to the alloy composition ratio, preheat the raw materials to be melted to 200℃ and dry them.

[0068] 2) Alloy smelting: heat to 750°C, add raw materials with calculated proportions into the furnace, including pure aluminum, pure Zn, Al-Si master alloy, Al-Mn master alloy, Al-Fe master alloy, Al-Ti master alloy, Al-V master alloy, Al-Hf master alloy, RE (La, Sc mixed rare earth) alloy for melting, wait for the above alloys to melt and cool to 720°C, add pure Mg, and press it into the bottom of the crucible with a tool to prevent Mg from burning on the liquid surface to ensure complete melting.

[0069] 3) Refining and degassing: keep the temperature at 720℃, add 0.3% refining agent by weight to the aluminum liquid, use argon rotary powder spraying refining and degassing equipment to degas the melt, the degassing time is 8 minutes, and after scraping off the slag on the liquid surface, let it stand for 10 minutes.

[0070] 4) Pouring ingot: The casting sample is subjected to spectral composition analysis, and after the composition is qualified, it is cast into an ingot.

[0071] 5) Die-casting process: the above aluminum alloy ingots are melted and then subjected to high-pressure die-casting. The above aluminum alloy ingots are melted and then subjected to high-pressure die-casting. The die-casting process adopts a die-casting pressure of 550 bar, an injection speed of 5.5 m / s, a vacuum degree of 20 mbar, a die-casting temperature of 700° C., and a mold temperature of 220° C.

[0072] 6) The die-casting mold is a flat mold and a mold for fluidity testing. The mechanical properties test is carried out by taking a tensile test piece from the die-cast flat mold casting body, and the fluidity is measured simultaneously. The flat mold body is sampled for SEM scanning electron microscopy analysis of the microstructure, and the solidus temperature is analyzed by DSC differential thermal scanner.

[0073] Example 3

[0074] This embodiment relates to a heat-treatment-free aluminum alloy for die casting that can be brazed, and the mass percentages of its components are as follows:

[0075] Si: 0.4wt.%, Mn: 2.5wt.%, Fe: 2.0wt.%, Mg: 0.45wt.%, Ti: 0.18wt.%, V: 0.012wt.%, Zn: 2.5wt.%, Hf: 0.014wt.%, RE: 0.06wt.%, RE is a mixed rare earth of Ce and Sc, in which the mass ratio of Ce and Sc is 7:3, and the balance is Al and unavoidable impurities, among which the total amount of impurities is ≤0.2%.

[0076] The preparation method of the above aluminum alloy is as follows:

[0077] 1) Material preparation and preheating: Prepare the materials according to the alloy composition ratio, preheat the raw materials to be melted to 200℃ and dry them.

[0078] 2) Alloy smelting: heat to 750°C, add the raw materials with calculated proportions into the furnace, including pure aluminum, pure Zn, Al-Si master alloy, Al-Mn master alloy, Al-Fe master alloy, Al-Ti master alloy, Al-V master alloy, Al-Hf master alloy, RE (Ce, Sc mixed rare earth) alloy for melting, wait for the above alloys to melt and cool to 720°C, add pure Mg, and press it into the bottom of the crucible with a tool to prevent Mg from burning on the liquid surface to ensure complete melting.

[0079] 3) Refining and degassing: keep the temperature at 720℃, add 0.3% refining agent by weight to the aluminum liquid, use argon rotary powder spraying refining and degassing equipment to degas the melt, the degassing time is 8 minutes, and after scraping off the slag on the liquid surface, let it stand for 10 minutes.

[0080] 4) Pouring ingot: The casting sample is subjected to spectral composition analysis, and after the composition is qualified, it is cast into an ingot.

[0081] 5) Die-casting process: the above aluminum alloy ingots are melted and then subjected to high-pressure die-casting. The above aluminum alloy ingots are melted and then subjected to high-pressure die-casting. The die-casting process adopts a die-casting pressure of 500 bar, an injection speed of 6 m / s, a vacuum degree of 25 mbar, a die-casting temperature of 710° C., and a mold temperature of 220° C.

[0082] 6) The die-casting mold is a flat mold and a mold for fluidity testing. The mechanical properties test is carried out by taking a tensile test piece from the die-cast flat mold casting body, and the fluidity is measured simultaneously. The flat mold body is sampled for SEM scanning electron microscopy analysis of the microstructure, and the solidus temperature is analyzed by DSC differential thermal scanner.

[0083] Example 4

[0084] This embodiment relates to a heat-treatment-free aluminum alloy for die casting that can be brazed, and the mass percentages of its components are as follows:

[0085] Si: 0.51wt.%, Mn: 1.6wt.%, Fe: 2.4wt.%, Mg: 0.3wt.%, Ti: 0.28wt.%, V: 0.005wt.%, Zn: 3.5wt.%, Hf: 0.003wt.%, RE: 1.0wt.%, RE is a mixed rare earth of La and Sc, in which the mass ratio of La and Sc is 6:4, and the balance is Al and unavoidable impurities, among which the total amount of impurities is ≤0.2%.

[0086] The preparation method of the above aluminum alloy is as follows:

[0087] 1) Material preparation and preheating: Prepare the materials according to the alloy composition ratio, preheat the raw materials to be melted to 200℃ and dry them.

[0088] 2) Alloy smelting: heat to 740°C, add raw materials with calculated proportions into the furnace, including pure aluminum, pure Zn, Al-Si master alloy, Al-Mn master alloy, Al-Fe master alloy, Al-Ti master alloy, Al-V master alloy, Al-Hf master alloy, RE (La, Sc mixed rare earth) alloy for melting, wait for the above alloys to melt and cool to 720°C, add pure Mg, and press it into the bottom of the crucible with a tool to prevent Mg from burning on the liquid surface to ensure complete melting.

[0089] 3) Refining and degassing: keep the temperature at 720℃, add 0.5% by weight of refining agent into the aluminum liquid, use argon rotary powder spraying refining and degassing equipment to degas the melt, the degassing time is 10 minutes, scrape off the scum on the liquid surface and let it stand for 10 minutes.

[0090] 4) Pouring ingot: The casting sample is subjected to spectral composition analysis, and after the composition is qualified, it is cast into an ingot.

[0091] 5) Die-casting process: the above aluminum alloy ingots are melted and then subjected to high-pressure die-casting. The above aluminum alloy ingots are melted and then subjected to high-pressure die-casting. The die-casting process adopts a die-casting pressure of 500 bar, an injection speed of 5 m / s, a vacuum degree of 30 mbar, a die-casting temperature of 690° C., and a mold temperature of 200° C.

[0092] 6) The die-casting mold is a flat mold and a mold for fluidity testing. The mechanical properties test is carried out by taking a tensile test piece from the die-cast flat mold casting body, and the fluidity is measured simultaneously. The flat mold body is sampled for SEM scanning electron microscopy analysis of the microstructure, and the solidus temperature is analyzed by DSC differential thermal scanner.

[0093] Example 5

[0094] This embodiment relates to a heat-treatment-free aluminum alloy for die casting that can be brazed, and the mass percentages of its components are as follows:

[0095] Si: 0.7wt.%, Mn: 1.3wt.%, Fe: 2.2wt.%, Mg: 0.25wt.%, Ti: 0.12wt.%, V: 0.1wt.%, Zn: 3.3wt.%, Hf: 0.012wt.%, RE: 0.01wt.%, RE is La rare earth, and the balance is Al and unavoidable impurities, among which the total amount of impurities is ≤0.2%.

[0096] The preparation method of the above aluminum alloy is as follows:

[0097] 1) Material preparation and preheating: Prepare the materials according to the alloy composition ratio, preheat the raw materials to be melted to 200℃ and dry them.

[0098] 2) Alloy smelting: heat to 750°C, add the raw materials with calculated proportions into the furnace, including pure aluminum, pure Zn, Al-Si master alloy, Al-Mn master alloy, Al-Fe master alloy, Al-Ti master alloy, Al-V master alloy, Al-Hf master alloy, RE (La rare earth) alloy for melting, wait for the above alloys to melt and cool to 720°C, add pure Mg, and press it into the bottom of the crucible with a tool to prevent Mg from burning on the liquid surface to ensure complete melting.

[0099] 3) Refining and degassing: keep the temperature at 720℃, add 0.4% by weight of refining agent into the aluminum liquid, use argon rotary powder spraying refining and degassing equipment to degas the melt, the degassing time is 8 minutes, and after scraping off the slag on the liquid surface, let it stand for 10 minutes.

[0100] 4) Pouring ingot: The casting sample is subjected to spectral composition analysis, and after the composition is qualified, it is cast into an ingot.

[0101] 5) Die-casting process: the above aluminum alloy ingots are melted and then subjected to high-pressure die-casting. The above aluminum alloy ingots are melted and then subjected to high-pressure die-casting. The die-casting process adopts a die-casting pressure of 450 bar, an injection speed of 6 m / s, a vacuum degree of 26 mbar, a die-casting temperature of 700° C., and a mold temperature of 230° C.

[0102] 6) The die-casting mold is a flat mold and a mold for fluidity testing. The mechanical properties test is carried out by taking a tensile test piece from the die-cast flat mold casting body, and the fluidity is measured simultaneously. The flat mold body is sampled for SEM scanning electron microscopy analysis of the microstructure, and the solidus temperature is analyzed by DSC differential thermal scanner.

[0103] Example 6

[0104] This embodiment relates to a heat-treatment-free aluminum alloy for die casting that can be brazed, and the mass percentages of its components are as follows:

[0105] Si: 0.5wt.%, Mn: 2.0wt.%, Fe: 1.8wt.%, Mg: 0.36wt.%, Ti: 0.08wt.%, V: 0.13wt.%, Zn: 1.6wt.%, Hf: 0.013wt.%, RE: 2.0wt.%, RE is a mixed rare earth of La, Ce and Sc, in which the mass ratio of La, Ce and Sc is 3:5:2, and the balance is Al and unavoidable impurities, and the total amount of impurities is ≤0.2%.

[0106] The preparation method of the above aluminum alloy is as follows:

[0107] 1) Material preparation and preheating: Prepare the materials according to the alloy composition ratio, preheat the raw materials to be melted to 200℃ and dry them.

[0108] 2) Alloy smelting: heat to 750°C, add the raw materials with calculated proportions into the furnace, including pure aluminum, pure Zn, Al-Si master alloy, Al-Mn master alloy, Al-Fe master alloy, Al-Ti master alloy, Al-V master alloy, Al-Hf master alloy, RE (La, Ce, Sc mixed rare earth) alloy for melting, wait for the above alloys to melt and cool to 720°C, add pure Mg, and press it into the bottom of the crucible with a tool to prevent Mg from burning on the liquid surface to ensure complete melting.

[0109] 3) Refining and degassing: keep the temperature at 720℃, add 0.5% by weight of refining agent into the aluminum liquid, use argon rotary powder spraying refining and degassing equipment to degas the melt, the degassing time is 10 minutes, scrape off the scum on the liquid surface and let it stand for 10 minutes.

[0110] 4) Pouring ingot: The casting sample is subjected to spectral composition analysis, and after the composition is qualified, it is cast into an ingot.

[0111] 5) Die-casting process: melt the above aluminum alloy ingots and then perform high-pressure die-casting. The above aluminum alloy ingots are melted and then perform high-pressure die-casting. The die-casting process adopts a die-casting pressure of 400 bar, an injection speed of 4.5 m / s, a vacuum degree of 30 mbar, a die-casting temperature of 710° C., and a mold temperature of 210° C.

[0112] 6) The die-casting mold is a flat mold and a mold for fluidity testing. The mechanical properties test is carried out by taking a tensile test piece from the die-cast flat mold casting body, and the fluidity is measured simultaneously. The flat mold body is sampled for SEM scanning electron microscopy analysis of the microstructure, and the solidus temperature is analyzed by DSC differential thermal scanner.

[0113] Example 7

[0114] This embodiment relates to a heat-treatment-free aluminum alloy for die casting that can be brazed, and the mass percentages of its components are as follows:

[0115] Si: 0.08wt.%, Mn: 3.0wt.%, Fe: 0.9wt.%, Mg: 0.8wt.%, Ti: 0.25wt.%, V: 0.008wt.%, Zn: 1.0wt.%, Hf: 0.015wt.%, RE: 2.3wt.%, RE is a mixed rare earth of Ce and Sc, in which the mass ratio of Ce and Sc is 7:3, and the balance is Al and unavoidable impurities, among which the total amount of impurities is ≤0.2%.

[0116] The preparation method of the above aluminum alloy is as follows:

[0117] 1) Material preparation and preheating: Prepare the materials according to the alloy composition ratio, preheat the raw materials to be melted to 200℃ and dry them.

[0118] 2) Alloy smelting: heat to 740°C, add raw materials with calculated proportions into the furnace, including pure aluminum, pure Zn, Al-Si master alloy, Al-Mn master alloy, Al-Fe master alloy, Al-Ti master alloy, Al-V master alloy, Al-Hf master alloy, RE (Ce, Sc mixed rare earth) alloy for melting, wait for the above alloys to melt and cool to 720°C, add pure Mg, and press it into the bottom of the crucible with a tool to prevent Mg from burning on the liquid surface to ensure complete melting.

[0119] 3) Refining and degassing: keep the temperature at 720℃, add 0.4% by weight of refining agent into the aluminum liquid, use argon rotary powder spraying refining and degassing equipment to degas the melt, the degassing time is 10 minutes, scrape off the slag on the liquid surface and let it stand for 10 minutes.

[0120] 4) Pouring ingot: The casting sample is subjected to spectral composition analysis, and after the composition is qualified, it is cast into an ingot.

[0121] 5) Die-casting process: the above aluminum alloy ingots are melted and then subjected to high-pressure die-casting. The above aluminum alloy ingots are melted and then subjected to high-pressure die-casting. The die-casting process adopts a die-casting pressure of 550 bar, an injection speed of 6 m / s, a vacuum degree of 20 mbar, a die-casting temperature of 710° C., and a mold temperature of 200° C.

[0122] 6) The die-casting mold is a flat mold and a mold for fluidity testing. The mechanical properties test is carried out by taking a tensile test piece from the die-cast flat mold casting body, and the fluidity is measured simultaneously. The flat mold body is sampled for SEM scanning electron microscopy analysis of the microstructure, and the solidus temperature is analyzed by DSC differential thermal scanner.

[0123] Example 8

[0124] This embodiment relates to a heat-treatment-free aluminum alloy for die casting that can be brazed, and the mass percentages of its components are as follows:

[0125] Si: 0.21wt.%, Mn: 2.6wt.%, Fe: 1.1wt.%, Mg: 0.6wt.%, Ti: 0.19wt.%, V: 0.016wt.%, Zn: 3.0wt.%, Hf: 0.016wt.%, RE: 1.6wt.%, RE is a mixed rare earth of Ce and Sc, in which the mass ratio of Ce and Sc is 8:2, and the balance is Al and unavoidable impurities, among which the total amount of impurities is ≤0.2%.

[0126] The preparation method of the above aluminum alloy is as follows:

[0127] 1) Material preparation and preheating: Prepare the materials according to the alloy composition ratio, preheat the raw materials to be melted to 200℃ and dry them.

[0128] 2) Alloy smelting: heat to 750°C, add the raw materials with calculated proportions into the furnace, including pure aluminum, pure Zn, Al-Si master alloy, Al-Mn master alloy, Al-Fe master alloy, Al-Ti master alloy, Al-V master alloy, Al-Hf master alloy, RE (Ce, Sc mixed rare earth) alloy for melting, wait for the above alloys to melt and cool to 720°C, add pure Mg, and press it into the bottom of the crucible with a tool to prevent Mg from burning on the liquid surface to ensure complete melting.

[0129] 3) Refining and degassing: keep the temperature at 720℃, add 0.5% by weight of refining agent into the aluminum liquid, use argon rotary powder spraying refining and degassing equipment to degas the melt, the degassing time is 10 minutes, scrape off the scum on the liquid surface and let it stand for 10 minutes.

[0130] 4) Pouring ingot: The casting sample is subjected to spectral composition analysis, and after the composition is qualified, it is cast into an ingot.

[0131] 5) Die-casting process: the above aluminum alloy ingots are melted and then subjected to high-pressure die-casting. The above aluminum alloy ingots are melted and then subjected to high-pressure die-casting. The die-casting process adopts a die-casting pressure of 500 bar, an injection speed of 5 m / s, a vacuum degree of 30 mbar, a die-casting temperature of 700° C., and a mold temperature of 200° C.

[0132] 6) The die-casting mold is a flat mold and a mold for fluidity testing. The mechanical properties test is carried out by taking a tensile test piece from the die-cast flat mold casting body, and the fluidity is measured simultaneously. The flat mold body is sampled for SEM scanning electron microscopy analysis of the microstructure, and the solidus temperature is analyzed by DSC differential thermal scanner.

[0133] Example 9

[0134] This embodiment relates to a heat-treatment-free aluminum alloy for die casting that can be brazed, and the mass percentages of its components are as follows:

[0135] Si: 0.2wt.%, Mn: 2.7wt.%, Fe: 0.7wt.%, Mg: 0.7wt.%, Ti: 0.13wt.%, V: 0.008wt.%, Zn: 0.5wt.%, Hf: 0.008wt.%, RE: 2.1wt.%, RE is La and Ce mixed rare earth, in which the mass ratio of La and Ce is 4:6, and the balance is Al and unavoidable impurities, and the total amount of impurities is ≤0.2%.

[0136] The preparation method of the above aluminum alloy is as follows:

[0137] 1) Material preparation and preheating: Prepare the materials according to the alloy composition ratio, preheat the raw materials to be melted to 200℃ and dry them.

[0138] 2) Alloy smelting: heat to 740°C, add raw materials with calculated proportions into the furnace, including pure aluminum, pure Zn, Al-Si master alloy, Al-Mn master alloy, Al-Fe master alloy, Al-Ti master alloy, Al-V master alloy, Al-Hf master alloy, RE (La, Ce mixed rare earth) alloy for melting, wait for the above alloys to melt and cool to 720°C, add pure Mg, and press it into the bottom of the crucible with a tool to prevent Mg from burning on the liquid surface to ensure complete melting.

[0139] 3) Refining and degassing: keep the temperature at 720℃, add 0.4% by weight of refining agent into the aluminum liquid, use argon rotary powder spraying refining and degassing equipment to degas the melt, the degassing time is 8 minutes, and after scraping off the slag on the liquid surface, let it stand for 10 minutes.

[0140] 4) Pouring ingot: The casting sample is subjected to spectral composition analysis, and after the composition is qualified, it is cast into an ingot.

[0141] 5) Die-casting process: melt the above aluminum alloy ingots and then perform high-pressure die-casting. The above aluminum alloy ingots are melted and then perform high-pressure die-casting. The die-casting process adopts a die-casting pressure of 450 bar, an injection speed of 6 m / s, a vacuum degree of 25 mbar, a die-casting temperature of 710° C., and a mold temperature of 210° C.

[0142] 6) The die-casting mold is a flat mold and a mold for fluidity testing. The mechanical properties test is carried out by taking a tensile test piece from the die-cast flat mold casting body, and the fluidity is measured simultaneously. The flat mold body is sampled for SEM scanning electron microscopy analysis of the microstructure, and the solidus temperature is analyzed by DSC differential thermal scanner.

[0143] Example 10

[0144] This embodiment relates to a heat-treatment-free aluminum alloy for die casting that can be brazed, and the mass percentages of its components are as follows:

[0145] Si: 0.35wt.%, Mn: 2.5wt.%, Fe: 1.5wt.%, Mg: 0.5wt.%, Ti: 0.08wt.%, V: 0.14wt.%, Zn: 2.0wt.%, Hf: 0.015wt.%, RE: 1.8wt.%, RE is a mixed rare earth of La, Ce and Sc, in which the mass ratio of La, Ce and Sc is 5:3:2, and the balance is Al and unavoidable impurities, and the total amount of impurities is ≤0.2%.

[0146] The preparation method of the above aluminum alloy is as follows:

[0147] 1) Material preparation and preheating: Prepare the materials according to the alloy composition ratio, preheat the raw materials to be melted to 200℃ and dry them.

[0148] 2) Alloy smelting: heat to 740°C, add raw materials with calculated proportions into the furnace, including pure aluminum, pure Zn, Al-Si master alloy, Al-Mn master alloy, Al-Fe master alloy, Al-Ti master alloy, Al-V master alloy, Al-Hf master alloy, RE (La, Ce, Sc mixed rare earth) alloy for melting, wait for the above alloys to melt and cool to 720°C, add pure Mg, and press it into the bottom of the crucible with a tool to prevent Mg from burning on the liquid surface to ensure complete melting.

[0149] 3) Refining and degassing: keep the temperature at 720℃, add 0.5% by weight of refining agent into the aluminum liquid, use argon rotary powder spraying refining and degassing equipment to degas the melt, the degassing time is 10 minutes, scrape off the scum on the liquid surface and let it stand for 10 minutes.

[0150] 4) Pouring ingot: The casting sample is subjected to spectral composition analysis, and after the composition is qualified, it is cast into an ingot.

[0151] 5) Die-casting process: melt the above aluminum alloy ingots and then perform high-pressure die-casting. The above aluminum alloy ingots are melted and then perform high-pressure die-casting. The die-casting process adopts a die-casting pressure of 500 bar, an injection speed of 5.5 m / s, a vacuum degree of 25 mbar, a die-casting temperature of 710° C., and a mold temperature of 230° C.

[0152] 6) The die-casting mold is a flat mold and a mold for fluidity testing. The mechanical properties test is carried out by taking a tensile test piece from the die-cast flat mold casting body, and the fluidity is measured simultaneously. The flat mold body is sampled for SEM scanning electron microscopy analysis of the microstructure, and the solidus temperature is analyzed by DSC differential thermal scanner.

[0153] Comparative Example 1

[0154] The mass percentages of the components of the aluminum alloy in this comparative example are as follows: Si: 0.2wt.%, Mn: 2.7wt.%, Fe: 0.7wt.%, Mg: 0.7wt.%, Ti: 0.13wt.%, Zn: 0.5wt.%, Hf: 0.008wt.%, and the remainder is Al and unavoidable impurities, wherein the total amount of impurities is ≤0.2%.

[0155] The preparation method of the aluminum alloy in this comparative example is the same as that in Example 9.

[0156] Comparative Example 2

[0157] The mass percentages of the components of the aluminum alloy in this comparative example are as follows: Si: 0.2wt.%, Mn: 2.7wt.%, Fe: 0.7wt.%, Mg: 0.7wt.%, Ti: 0.13wt.%, V: 0.008wt.%, Zn: 0.5wt.%, and the remainder is Al and unavoidable impurities, wherein the total amount of impurities is ≤0.2%.

[0158] The preparation method of the aluminum alloy in this comparative example is the same as that in Example 9.

[0159] Comparative Example 3

[0160] The mass percentages of the components of the aluminum alloy in this comparative example are as follows: Si: 0.2wt.%, Mn: 2.7wt.%, Fe: 0.7wt.%, Ti: 0.13wt.%, V: 0.008wt.%, Hf: 0.008wt.%, and the remainder is Al and unavoidable impurities, wherein the total amount of impurities is ≤0.2%.

[0161] The preparation method of the aluminum alloy in this comparative example is the same as that in Example 9.

[0162] Comparative Example 4

[0163] The mass percentages of the components of the aluminum alloy in this comparative example are as follows: Si: 0.2wt.%, Mn: 2.7wt.%, Fe: 0.7wt.%, Ti: 0.13wt.%, Zn: 0.5wt.%, RE: 2.1wt.%, RE is a mixed rare earth of La and Ce, wherein the mass ratio of La to Ce is 4:6, and the remainder is Al and unavoidable impurities, wherein the total amount of impurities is ≤0.2%.

[0164] The preparation method of the aluminum alloy in this comparative example is the same as that in Example 9.

[0165] Comparative Example 5

[0166] The mass percentages of the components of the aluminum alloy in this comparative example are as follows:

[0167] Si: 0.2wt.%, Mn: 2.7wt.%, Fe: 0.7wt.%, Ti: 0.13wt.%, V: 0.008wt.%, RE: 2.1wt.%, RE is La and Ce mixed rare earth, in which the mass ratio of La and Ce is 4:6, and the balance is Al and unavoidable impurities, among which the total amount of impurities is ≤0.2%.

[0168] The preparation method of the aluminum alloy in this comparative example is the same as that in Example 9.

[0169] Comparative Example 6

[0170] The mass percentages of the components of the aluminum alloy in this comparative example are as follows: Si: 0.2wt.%, Mn: 2.7wt.%, Fe: 0.7wt.%, Mg: 0.7wt.%, Ti: 0.13wt.%, and the remainder is Al and unavoidable impurities, wherein the total amount of impurities is ≤0.2%.

[0171] The preparation method of the aluminum alloy in this comparative example is the same as that in Example 9.

[0172] Comparative Example 7

[0173] The mass percentages of the components of the aluminum alloy in this comparative example are as follows: Si: 0.2wt.%, Mn: 2.7wt.%, Fe: 0.7wt.%, Ti: 0.13wt.%, and the remainder is Al and unavoidable impurities, wherein the total amount of impurities is ≤0.2%.

[0174] The preparation method of the aluminum alloy in this comparative example is the same as that in Example 9.

[0175] Table 1 (mass fraction wt.%)

[0176]

[0177] Table 2 (mechanical properties, solidus temperature, fluidity)

[0178]

[0179]

[0180] Table 1 shows the mass fraction of the aluminum alloy materials of Examples 1-10 and Comparative Examples 1-7, and Table 2 shows the mechanical properties, solidus temperature, and fluidity test results of the die-cast aluminum alloy corresponding to Table 1. According to the results of each embodiment and comparative example in Table 1 and Table 2, it can be seen from the comparison between Example 9 and Comparative Examples 1-7 that when the alloy is not added with elements such as Mg, V, Zn, Hf, and RE rare earth, the mechanical properties of the alloy are greatly reduced, the solidus temperature is reduced, and the fluidity is deteriorated, which indicates that when Mg, V, Zn, Hf, and RE rare earth are added to the aluminum matrix in a certain proportion, a synergistic strengthening effect is played, which can effectively improve the tensile strength, yield strength, and elongation of the alloy, and achieve the effect of stabilizing the mechanical properties of the alloy.

[0181] Figure 1 This is a scanning electron microscope (SEM) microstructure image of the alloy of Example 9 of the present invention. The microstructure morphology of the alloy of the present invention can be observed. In the ɑ-Al matrix, there are a network-distributed Al rare earth phase, a block-shaped AlMnFe phase, and a dispersed granular MgSi phase. It can be observed that the second phase is distributed relatively evenly, which can play a better strengthening role. Figure 2 This is a DSC curve analysis result diagram of the alloy of Example 4 of the present invention. The test results show that the solidus temperature of the alloy is 631.15°C, which is higher than the commonly used vacuum brazing temperature of 610°C and can meet the use requirements of brazing aluminum alloys. Figure 3 This is a diagram of the fluidity mold test results of the alloy in Example 1 of the present invention. The experimental test shows that the alloy has good fluidity and the material has good die-casting performance.

[0182] In summary, the present invention optimizes the alloy composition on the basis of Al-Mn alloy, by adding a certain proportion of Si, Fe, Mg, Zn, V, Ti and trace elements Hf, and RE rare earth elements, RE including at least one of La / Ce / Sc and above. The strengthening mechanism of various elements is maximized, and the elements play a synergistic strengthening role with each other, and higher mechanical properties can be achieved without heat treatment to meet the use requirements. Within the scope of this alloy system, the element ratio is regulated to effectively increase the solidus temperature of the aluminum alloy on the basis of ensuring good mechanical properties. The results show that the solidus temperature of the alloy of the present invention is much higher than the brazing temperature, which fully meets the practical requirements, and the alloy has good fluidity and is suitable for high-pressure casting. In summary, the alloy of the present invention has excellent brazing properties and good castability, which not only effectively solves the problem of low melting point of aluminum alloy for brazing in the current industry, but also effectively connects die-casting technology with brazing technology to achieve the purpose of improving the efficiency of the production link, so it has a very broad application prospect in the future automobile production field.

[0183] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A die-casting aluminum alloy suitable for brazing, characterized in that: The mass percentage contents of the alloy components are as follows: Si: 0.05 - 0.7 wt.%, Mn: 1.3 - 3.4 wt.%, Fe: 0.7 - 2.4 wt.%, Mg: 0.25 - 0.9 wt.%, Ti: 0.06 - 0.28 wt.%, V: 0.005 - 0.16 wt.%, Zn: 0.5 - 3.5 wt.%, Hf: 0.003 - 0.016 wt.%, RE: 0.01 - 2.5 wt.%, RE includes at least one or more of La, Ce and Sc, the balance being Al and unavoidable impurities, where the total amount of impurities ≤ 0.2%; Among them, the mass percentage contents of Fe and Mn satisfy: 0.2 < Fe:Mn < 2; the mass percentage contents of Si and Mg satisfy: 0.05 < Si:Mg < 3; the mass percentage contents of RE and Mn satisfy: 0.01 < RE:Mn < 2; the mass percentage contents of Zn and Mn satisfy: 0.1 < Zn:Mn < 2.7; The preparation method of the die-casting aluminum alloy suitable for brazing includes the following steps: melting the raw materials according to the alloy composition ratio, then refining and exhausting the melt, obtaining an aluminum alloy ingot after casting, and then die-casting the aluminum alloy ingot to obtain the die-casting aluminum alloy suitable for brazing; The conditions for die-casting are: die-casting pressure 400 - 550 bar, injection speed 4 - 6 m / s, vacuum degree < 40 mbar, die-casting temperature 690 - 730 °C, mold temperature 200 - 230 °C; The solidus temperature of the die-casting aluminum alloy suitable for brazing ≥ 631.15 °C; the tensile strength of the die-casting aluminum alloy in the as-cast state ≥ 262 MPa, the yield strength ≥ 144 MPa, and the elongation ≥ 11.2%; 2. The die-casting aluminum alloy suitable for brazing according to claim 1, characterized in that: The mass percentage contents of the alloy components are as follows: Si: 0.05 - 0.2 wt.%, Mn: 2.7 - 3.4 wt.%, Fe: 0.7 - 1.0 wt.%, Mg: 0.7 - 0.9 wt.%, Ti: 0.06 - 0.28 wt.%, V: 0.005 - 0.16 wt.%, Zn: 0.5 - 1.5 wt.%, Hf: 0.003 - 0.016 wt.%, RE: 2.1 - 2.5 wt.%, RE includes at least one or more of La, Ce and Sc, the balance being Al and unavoidable impurities, where the total amount of impurities ≤ 0.2%; Among them, the mass percentage contents of Fe and Mn satisfy: 0.2 < Fe:Mn < 2; the mass percentage contents of Si and Mg satisfy: 0.05 < Si:Mg < 3; the mass percentage contents of RE and Mn satisfy: 0.01 < RE:Mn < 2; the mass percentage contents of Zn and Mn satisfy: 0.1 < Zn:Mn < 2.7; 3. The die-casting aluminum alloy suitable for brazing according to claim 1, characterized in that: The mass percentage contents of the alloy components are as follows: Si: 0.21 - 0.5 wt.%, Mn: 2.0 - 2.6 wt.%, Fe: 1.1 - 2.0 wt.%, Mg: 0.36 - 0.6 wt.%, Ti: 0.06 - 0.28 wt.%, V: 0.005 - 0.16 wt.%, Zn: 1.6 - 3.0 wt.%, Hf: 0.003 - 0.016 wt.%, RE: 1.6 - 2.0 wt.%, RE includes at least one or more of La, Ce, and Sc, the balance being Al and unavoidable impurities, where the total impurity content ≤ 0.2%; Among them, the mass percentage contents of Fe and Mn satisfy: 0.2 < Fe:Mn < 2; the mass percentage contents of Si and Mg satisfy: 0.05 < Si:Mg < 3; the mass percentage contents of RE and Mn satisfy: 0.01 < RE:Mn < 2; the mass percentage contents of Zn and Mn satisfy: 0.1 < Zn:Mn < 2.

7.

4. The die-casting aluminum alloy suitable for brazing according to claim 1, characterized in that: The mass percentage contents of the alloy components are as follows: Si: 0.51 - 0.7 wt.%, Mn: 1.3 - 1.9 wt.%, Fe: 2.1 - 2.4 wt.%, Mg: 0.25 - 0.35 wt.%, Ti: 0.06 - 0.28 wt.%, V: 0.005 - 0.16 wt.%, Zn: 3.1 - 3.5 wt.%, Hf: 0.003 - 0.016 wt.%, RE: 0.01 - 1.5 wt.%, RE includes at least one or more of La, Ce, and Sc, the balance being Al and unavoidable impurities, where the total impurity content ≤ 0.2%; Among them, the mass percentage contents of Fe and Mn satisfy: 0.2 < Fe:Mn < 2; the mass percentage contents of Si and Mg satisfy: 0.05 < Si:Mg < 3; the mass percentage contents of RE and Mn satisfy: 0.01 < RE:Mn < 2; the mass percentage contents of Zn and Mn satisfy: 0.1 < Zn:Mn < 2.

7.

5. The die-casting aluminum alloy suitable for brazing according to claim 1, characterized in that: The mass percentage contents of the alloy components are as follows: Si: 0.05 wt.%, Mn: 3.4 wt.%, Fe: 1.0 wt.%, Mg: 0.9 wt.%, Ti: 0.06 wt.%, V: 0.16 wt.%, Zn: 1.5 wt.%, Hf: 0.015 wt.%, RE: 2.5 wt.%, RE includes at least one or more of La, Ce, and Sc, the balance being Al and unavoidable impurities, where the total impurity content ≤ 0.2%.

6. The die-casting aluminum alloy suitable for brazing according to claim 1, characterized in that: The mass percentage contents of the alloy components are as follows: Si: 0.5 wt.%, Mn: 2.0 wt.%, Fe: 1.8 wt.%, Mg: 0.36 wt.%, Ti: 0.08 wt.%, V: 0.13 wt.%, Zn: 1.6 wt.%, Hf: 0.013 wt.%, RE: 2.0 wt.%, RE includes at least one or more of La, Ce, and Sc, the balance being Al and unavoidable impurities, where the total impurity content ≤ 0.2%.

7. The die-casting aluminum alloy suitable for brazing according to claim 1, characterized in that: The mass percentage contents of the alloy components are as follows: Si: 0.7wt.%, Mn: 1.3wt.%, Fe: 2.2wt.%, Mg: 0.25wt.%, Ti: 0.12wt.%, V: 0.10wt.%, Zn: 3.3wt.%, Hf: 0.012wt.%, RE: 0.01wt.%, RE includes at least one or more of La, Ce and Sc, and the balance is Al and unavoidable impurities, wherein the total amount of impurities is ≤0.2%.

Images