Aluminum alloy material for brazing, preparation method of aluminum alloy material and brazing process of aluminum alloy material for brazing

Abstract

The invention provides an aluminum alloy material for brazing, a preparation method of the aluminum alloy material and a brazing process of the aluminum alloy material for brazing. The aluminum alloy material for brazing comprises, by mass, 3.0%-12.0% of rare earth metal element RE, 0.06%-0.85% of Fe, 0.5%-1.2% of Mn, 0.1%-0.5% of Cr, 0.02%-0.5% of Mg, 0.1%-0.2% of Ti, 0.02%-0.2% of V, 0.02%-0.1% of B, smaller than or equal to 0.15% of Si, smaller than or equal to 0.02% of Cu and the balance Al and inevitable impurities, and the content of a single impurity element is smaller than or equal to 0.05%. Wherein the solidus temperature of the aluminum alloy material for brazing is larger than or equal to 625 DEG C. The problem that in the prior art, aluminum alloy is poor in casting performance and brazing quality is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of aluminum alloys, and in particular, to an aluminum alloy material for brazing, a preparation method thereof, and a brazing process for the aluminum alloy material for brazing. Background Art

[0002] High-pressure die casting (referred to as die casting for short) refers to a near-net shape forming technology in which liquid or semi-liquid metal is filled into a die casting mold cavity at a relatively high speed under high pressure and solidifies under pressure. During the die casting process, the pressure on the molten metal is generally 20 - 200 MPa, the speed when filling the ingate reaches 15 - 70 m / s, and the filling time is only 0.01 - 0.2 s, which has a high production efficiency.

[0003] Brazing refers to a welding method in which a filler metal with a melting point lower than that of the workpiece and the workpiece are simultaneously heated to the melting temperature of the filler metal, and then the liquid filler metal is used to fill the gaps between the solid workpieces to connect the metals. Aluminum alloy protective atmosphere brazing usually requires the use of an appropriate protective atmosphere during the brazing process to ensure high-quality connections and prevent oxidation. Argon or nitrogen is usually used as the protective atmosphere for the brazing of aluminum alloys because argon or nitrogen can effectively reduce the presence of oxygen, thereby preventing oxidation. For example, a certain gas shielded brazing controls the composition of the brazing flux continuously so that it can reach a temperature close to the melting point (565 °C), and the melting point range of the brazing flux is 565 °C - 572 °C. Once the brazing flux melts, an oxide film is generated on the surface of the melted part. Subsequently, the brazing layer alloy (also called the composite layer) melts, and the melted brazing layer metal freely flows into the joint by capillary action. When the part cools down, the melted brazing layer metal solidifies and forms a metallographic joint.

[0004] Traditional die-cast aluminum alloy materials generally contain relatively high amounts of elements such as Si, Cu, Mg, etc., making the eutectic point and the temperature of the solid-liquid phase line of the aluminum alloy material relatively low, generally lower than the brazing temperature. In addition, traditional die-cast parts are filled into the mold cavity at a high speed, and the castings generally have a high gas content. When brazed at high temperature, the pores on the surface of the casting expand due to heat, resulting in false brazing. Therefore, traditional die-cast parts are not suitable for the brazing process to connect and seal. In the traditional aluminum alloy system, there are not many main alloying elements with high-temperature stability (such as Ni, Mn, Fe, etc.), but these elements are expensive, or the volume fraction of the eutectic phase formed with aluminum elements is relatively low, resulting in poor casting performance and unable to meet the requirements of the high-pressure die-casting process for forming. To ensure the brazing quality of die-cast parts and meet the mechanical properties of high-efficiency, low-cost casting of core complex structural parts for thermal management, it is necessary to develop a new die-cast aluminum alloy system to meet the requirements of die casting and brazing. Summary of the Invention

[0005] The main object of the present invention is to provide an aluminum alloy material for brazing, its preparation method, and a brazing process for the aluminum alloy material for brazing, so as to solve the problems of poor casting performance and brazing quality of aluminum alloys in the prior art.

[0006] To achieve the above object, according to one aspect of the present invention, there is provided an aluminum alloy material for brazing. By mass percentage, the aluminum alloy material for brazing includes: rare earth metal element RE with a content of 3.0 - 12.0%, Fe with a content of 0.06 - 0.85%, Mn with a content of 0.5 - 1.2%, Cr with a content of 0.1 - 0.5%, Mg with a content of 0.02 - 0.5%, Ti with a content of 0.1 - 0.2%, V with a content of 0.02 - 0.2%, B with a content of 0.02 - 0.1%, Si with a content ≤ 0.15%, Cu with a content ≤ 0.02%, the balance being Al and unavoidable impurities, and the content of a single impurity element ≤ 0.05%; wherein, the solidus temperature of the aluminum alloy material for brazing ≥ 625°C.

[0007] Further, in the above aluminum alloy material for brazing, Al 11 The mass ratio of the RE3 phase is 11 - 15%, the mass ratio of the Al6Mn phase is 1 - 7%, and the mass ratio of the Al7Cr phase is 1 - 5%.

[0008] Further, the content of the above Fe is 0.35 - 0.8%, and / or the content of Mn is 0.65 - 1.2%; preferably, the mass ratio of Fe to Mn is 0.4 - 1.2:1, and further preferably, it is 0.5 - 0.8:1.

[0009] Further, the above rare earth metal element RE is La and Ce, and preferably the mass ratio of La to Ce is 2.0 - 6.0:1.

[0010] Further, the yield strength of the above aluminum alloy material for brazing > 80 MPa, the fracture elongation rate > 7.0%, the tensile strength > 180 MPa, and the electrical conductivity ≥ 13.0 ms / s.

[0011] According to another aspect of the present invention, there is provided a preparation method for the aforementioned aluminum alloy material for brazing. The preparation method includes: Step S1, melting rare earth metal element RE, Fe, Mn, Cr, Mg, Ti, V, B, Si, and Cu in the form of alloys or single substances respectively with aluminum ingots to obtain aluminum alloy liquid; Step S2, degassing the aluminum alloy liquid to obtain degassed aluminum alloy liquid; Step S3, die-casting the degassed aluminum alloy liquid to obtain the aluminum alloy material for brazing.

[0012] Further, in the above step S3, the die-casting temperature is 710 - 730 °C, and / or the vacuum degree of the die-casting mold cavity is 35 - 50 mBar, and / or the die-casting pressure is 26.5 - 36.5 MPa, and / or the injection speed of die-casting is 2 - 3 m / s, and / or the mold temperature of die-casting is 120 - 140 °C, and / or the temperature of the degassed aluminum alloy liquid is 680 - 700 °C.

[0013] Further, the temperature of the above melting is 690 - 750 °C, preferably 720 - 750 °C.

[0014] Further, the above degassing is chemical degassing. Preferably, the reagent used for chemical degassing is a sodium-free refining agent for aluminum alloy, and / or the degassing time is 10 - 20 min, and / or the degassing temperature is 700 - 720 °C, and / or the gas content of the degassed aluminum alloy liquid is < 0.15 mL / 100 g.

[0015] According to another aspect of the present invention, there is provided a brazing process for the aforementioned aluminum alloy material for brazing. The brazing process includes steps of spraying a brazing flux, degreasing, drying, preheating, brazing, and cooling the aluminum alloy material for brazing in sequence. It is characterized in that before the step of spraying the brazing flux, the aluminum alloy material for brazing is subjected to a baking treatment to obtain a brazed aluminum alloy material; preferably, the temperature of the baking treatment is 550 - 610 °C, and / or the time of the baking treatment is 1 - 3 h.

[0016] Applying the technical solution of the present invention, adding rare earth metal element RE to the aluminum alloy material for brazing helps to form a high eutectic point and high-temperature stable phase, thereby forming a framework of the aluminum alloy material system that can be brazed; adding elements Fe, Mn, and Cr to the aluminum alloy material for brazing is beneficial to improving the anti-sticking property during the die-casting process; adding element Mg helps to improve the solution strengthening effect; adding elements Ti, V, and B is beneficial to achieving tissue uniformity and preventing segregation. By controlling the content of each element within the above range, especially by controlling the content of rare earth metal element RE, the present invention enhances the synergistic cooperation among the elements, making the structure of the aluminum alloy material uniform and the grains fine, with good castability, fluidity, thermal crack resistance, and weldability. In addition, controlling the solidus temperature of the aluminum alloy material for brazing ≥ 625 °C helps to minimize the brazing temperature while meeting the brazing requirements, thereby reducing the diffusion and erosion of the weld joint structure and further improving the weld joint strength. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The specification drawings forming a part of this application are used to provide a further understanding of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings:

[0018] Figure 1 Fig. 1 shows a 1000 - fold metallographic structure diagram of an aluminum alloy material for brazing provided according to Embodiment 1 of the present invention;

[0019] Figure 2 Fig. 2 shows a 100 - fold metallographic structure diagram of a brazed weld between an aluminum alloy material for brazing provided according to Embodiment 1 of the present invention and AA3003 / 4045 aluminum plates.

[0020] Among them, the above - mentioned drawings include the following reference numerals:

[0021] 1. Casting; 2. Weld; 3. AA3003 / 4045 aluminum plate. Detailed implementation manners

[0022] It should be noted that, without conflict, the embodiments in the present application and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the drawings and in combination with the embodiments.

[0023] As analyzed in the background art, traditional die - cast aluminum alloy materials generally contain relatively high contents of elements such as Si, Cu, and Mg, making the eutectic point and the solid - liquid phase line temperature of the aluminum alloy material relatively low, generally lower than the brazing temperature. In addition, traditional die - cast parts are filled into the mold cavity at high speed, and the castings generally have a high gas content. When brazing at high temperature, the pores on the surface of the casting expand due to heat, resulting in poor brazing and virtual soldering. Therefore, traditional die - cast parts are not suitable for the brazing process for connection and sealing. To ensure the brazing quality of die - castings and meet the mechanical properties of high - efficiency and low - cost casting heat - management core complex - structure parts, it is necessary to develop a new die - cast aluminum alloy system and its forming and brazing processes. In traditional aluminum alloy systems, there are not many main alloying elements with high - temperature stability, such as nickel (Ni), manganese (Mn), and mixed iron (Fe), etc. However, these elements are expensive, or the volume fraction of the eutectic phase formed with aluminum elements is relatively low, resulting in poor casting performance and unable to meet the requirements of the high - pressure die - casting process for forming. That is, there are problems of poor casting performance and brazing quality of aluminum alloys in the prior art. To solve this problem, the present invention provides an aluminum alloy material for brazing, its preparation method, and a brazing process for the aluminum alloy material for brazing.

[0024] In a typical embodiment of the present application, a brazing aluminum alloy material is provided. By mass percentage, the brazing aluminum alloy material includes: rare earth metal element RE with a content of 3.0 - 12.0%, Fe with a content of 0.06 - 0.85%, Mn with a content of 0.5 - 1.2%, Cr with a content of 0.1 - 0.5%, Mg with a content of 0.02 - 0.5%, Ti with a content of 0.1 - 0.2%, V with a content of 0.02 - 0.2%, B with a content of 0.02 - 0.1%, Si with a content ≤ 0.15%, Cu with a content ≤ 0.02%, and the balance is Al and unavoidable impurities, and the content of a single impurity element ≤ 0.05%; wherein, the solidus temperature of the brazing aluminum alloy material ≥ 625 °C.

[0025] Adding rare earth metal element RE to the brazing aluminum alloy material helps to form a high eutectic point and high-temperature stable phases, thereby forming a framework of a brazable aluminum alloy material system; adding elements Fe, Mn, and Cr to the brazing aluminum alloy material is beneficial to improving the anti-sticking property during the die-casting process; adding element Mg helps to improve the solution strengthening effect; adding elements Ti, V, and B is beneficial to achieving tissue uniformity and preventing segregation; by controlling the content of each element within the above ranges, especially by controlling the content of rare earth metal element RE, the present invention enhances the synergistic cooperation among the elements, making the structure of the aluminum alloy material uniform and the grains fine, and having good castability, fluidity, thermal cracking resistance, and weldability.

[0026] In addition, controlling the solidus temperature of the brazing aluminum alloy material ≥ 625 °C helps to minimize the brazing temperature on the premise of meeting the brazing requirements, thereby reducing the diffusion and erosion of the weld structure, and further improving the weld strength.

[0027] In an embodiment of the present application, in the above-mentioned brazing aluminum alloy material, Al 11 The mass ratio of the AlRE3 phase is 11 - 15%, the mass ratio of the Al6Mn phase is 1 - 7%, and the mass ratio of the Al7Cr phase is 1 - 5%.

[0028] Preferably, controlling the mass ratio of the Al 11 RE3 phase within the above range helps to improve the casting performance of the brazing aluminum alloy material; the dispersed Al6Mn phase and Al7Cr phase are beneficial to inhibiting the growth of recrystallized grains in the aluminum alloy material. Controlling the mass ratio of the Al6Mn phase and Al7Cr phase within the above range is beneficial to better refining the grains.

[0029] In order to further improve the synergistic cooperation of Fe and Mn, thereby improving the anti-sticking property of the aluminum alloy material for brazing during the die-casting process, in an embodiment of the present application, it is preferred that the content of Fe is 0.35-0.8%, and / or the content of Mn is 0.65-1.2%; preferably, the mass ratio of Fe to Mn is 0.4-1.2:1, and further preferably 0.5-0.8:1.

[0030] In order to further increase the solidus temperature of the aluminum alloy material for brazing, thereby improving the casting performance of the aluminum alloy material for brazing, in an embodiment of the present application, it is preferred that the rare earth metal element RE is La and Ce, and preferably the mass ratio of La to Ce is 2.0-6.0:1.

[0031] In some embodiments of the present application, the yield strength of the aluminum alloy material for brazing > 80 MPa, the fracture elongation rate > 7.0%, the tensile strength > 180 MPa, and the electrical conductivity ≥ 13.0 ms / s.

[0032] The aluminum alloy material for brazing with the above characteristics has better fluidity and thermal crack resistance, and can thus better meet the market demand.

[0033] In another typical embodiment of the present application, a preparation method of the aforementioned aluminum alloy material for brazing is provided. The preparation method includes: Step S1, melting rare earth metal element RE, Fe, Mn, Cr, Mg, Ti, V, B, Si, and Cu in the form of alloys or single substances respectively with aluminum ingots to obtain aluminum alloy liquid; Step S2, degassing the aluminum alloy liquid to obtain degassed aluminum alloy liquid; Step S3, die-casting the degassed aluminum alloy liquid to obtain the aluminum alloy material for brazing.

[0034] First, completely melt the aluminum ingots to form aluminum liquid, and then add RE, Fe, Mn, Cr, Mg, Ti, V, B, Si, and Cu in the form of alloys or single substances respectively to the aluminum liquid for melting to obtain aluminum alloy liquid; the gas in the aluminum alloy liquid is not conducive to forming a brazing aluminum alloy material without pores and impurities. Degassing the aluminum alloy liquid helps to reduce the defects of the brazing aluminum alloy material; the degassed aluminum alloy liquid is die-cast by a die-casting machine to obtain the aluminum alloy material for brazing. And by controlling the content of each element within the above range and combining the above preparation method, the present invention makes the structure of the aluminum alloy material uniform and the grains fine, having good castability, fluidity, thermal crack resistance, and weldability.

[0035] In an embodiment of the present application, in the above step S3, the die-casting temperature is 710 - 730 °C, and / or the vacuum degree of the die-casting mold cavity is 35 - 50 mBar, and / or the die-casting pressure is 26.5 - 36.5 MPa, and / or the injection speed of die-casting is 2 - 3 m / s, and / or the temperature of the die-casting mold is 120 - 140 °C, and / or the temperature of the degassed aluminum alloy liquid is 680 - 700 °C.

[0036] Since the solid-liquid phase temperature of the aluminum alloy material for brazing in the present application is relatively high, preferably, the die-casting temperature within the above range helps to ensure the high fluidity of the aluminum liquid. Preferably, controlling the vacuum degree of the mold cavity within the above range helps to reduce the porosity defects of the aluminum alloy material for brazing; if the die-casting pressure is too small, it is not conducive to the tight combination between aluminum alloy particles, and if the die-casting pressure is too large, it will shorten the service life of the mold. Preferably, controlling the die-casting pressure within the above range helps to balance the strength of the aluminum alloy material for brazing and the service life of the mold; if the injection speed of die-casting is too small, it is not conducive to the forming of the aluminum alloy material for brazing, and if the injection speed of die-casting is too large, it is not conducive to the control of the dimensional accuracy of the aluminum alloy material for brazing. Preferably, controlling the injection speed of die-casting within the above range helps to improve the appearance quality of the aluminum alloy material for brazing; preferably, controlling the temperature of the die-casting mold within the above range is beneficial to reducing the appearance defects of the aluminum alloy material for brazing; preferably, controlling the temperature of the degassed aluminum alloy liquid within the above range is beneficial to the better forming of the aluminum alloy material for brazing.

[0037] In addition, during the die-casting process, preferably, the number of mold ejector pins is 1.2 - 1.5 times that in the traditional die-casting process, which is more conducive to reducing the deformation rate of the aluminum alloy material.

[0038] In order to make the alloy or single substance of aluminum ingot and other elements melt more fully, in an embodiment of the present application, preferably, the melting temperature is 690 - 750 °C, and preferably 720 - 750 °C.

[0039] In an embodiment of the present application, the above degassing is chemical degassing. The reagent used for chemical degassing is a sodium-free refining agent for aluminum alloy, and / or the degassing time is 10 - 20 min, and / or the degassing temperature is 700 - 720 °C, and / or the gas content of the degassed aluminum alloy liquid is < 0.15 mL / 100 g.

[0040] It is preferable to use the above-mentioned sodium-free refining agent for aluminum alloy degassing, which helps to reduce the formation of pores or impurities in the aluminum alloy material for brazing; it is preferable that the sodium-free refining agent for aluminum alloy is selected from the above-mentioned types, which is conducive to enriching the selectivity of the sodium-free refining agent for aluminum alloy; too short degassing time or too low temperature is not conducive to gas discharge, and too long degassing time or too high temperature is not conducive to resource conservation. It is preferable to control the degassing time and temperature within the above ranges, which helps to better discharge the gas in the aluminum alloy liquid without wasting resources; it is preferable to control the gas content in the aluminum alloy liquid after degassing within the above range, which helps to better reduce the probability of pores or impurities in the aluminum alloy material for brazing. Specifically, the gas content is detected by a hydrogen detector, and when the gas content reaches below 0.15 mL / 100 g, it is die-cast by a high-pressure die-casting device. If the gas content does not meet the standard, the degassing in step S2 should be continued.

[0041] In addition, after step S2, it is detected whether the content of each element in the effective aluminum alloy liquid reaches the use standard. If so, it proceeds to step S3. If not, the mass percentage of a certain original element in the aluminum alloy liquid does not reach the above preset mass percentage, and an additional mass percentage of the element needs to be added to adjust the mass percentage of the element in the effective aluminum alloy liquid so that the mass percentage of the element meets the use standard, that is, reaches the preset mass percentage.

[0042] In another typical embodiment of the present application, a brazing process for the aforementioned aluminum alloy material for brazing is provided. The brazing process includes: successively spraying a brazing flux, degreasing, drying, preheating, brazing, and cooling steps on the aluminum alloy material for brazing. Before the step of spraying the brazing flux, the aluminum alloy material for brazing is baked to obtain the aluminum alloy material after brazing; preferably, the baking temperature is 550-610 °C, and / or the baking time is 1-3 h.

[0043] Before spraying the flux, the aluminum alloy material for brazing is baked. On the one hand, it helps to discharge the gas in the aluminum alloy material for brazing. On the other hand, during the process of gas discharge, the aluminum alloy material for brazing will have varying degrees of bulging, and the aluminum alloy materials suitable for brazing can be screened according to the degree of bulging. Preferably, controlling the temperature and time of the baking treatment within the above ranges helps to improve the exhaust efficiency. Specifically, a flux spraying device is used to spray the flux onto the AA3003 / 4045 aluminum plate, degreasing is carried out in a furnace cavity at 90 - 110°C, then drying is carried out at 270 - 290°C, and preheating is carried out in a furnace cavity at 540 - 560°C. Compared with the brazing temperature of 610°C - 630°C in conventional brazing, this material is brazed in a furnace cavity at 580 - 610°C. On the premise of meeting the brazing requirements, the brazing temperature is reduced as much as possible, which can reduce the diffusion and erosion of the weld structure, thereby improving the weld strength. Finally, after water cooling or air cooling, the brazing process is completed. It should be noted that due to the special properties of the aluminum alloy material for brazing, the oxygen and moisture content in the furnace cavity should be controlled. The protective atmosphere requires high-purity nitrogen, the oxygen content in the furnace cavity should be less than 20 ppm, and at the same time, the nitrogen dew point is controlled below -40°C. The results show that after high-temperature brazing of the aluminum alloy material for brazing in this application, there are no obvious pores, false soldering, and local erosion phenomena in the weld area.

[0044] As Figure 2 shown, Figure 2 It shows that the aluminum alloy material for brazing in this application has extremely low gas content and relatively high solid-liquid phase temperature, and there are no obvious defects during high-temperature brazing. In addition, the weld structure forms a good Al-Si eutectic structure, which can improve the strength of the weld. At the same time, the grain size in the diffusion area of the weld has no abnormally large coarsening and segregation, indicating that the aluminum alloy material for brazing in this application has good weldability and meets the design requirements.

[0045] The beneficial effects of this application will be described below in combination with specific examples and comparative examples.

[0046] The production equipment and auxiliary accessories used in the following examples and comparative examples: a 280T die-casting machine equipped with an automatic ladle and a mold temperature controller, a vacuum machine with extremely low vacuum degree, a mold structure with a sealing system, using a special mold release agent and punch lubrication system for die-cast structural parts, a 3mm * 80mm * 250mm self-made test piece mold, a 50mm diameter punch, and a melting cup.

[0047] Example 1

[0048] The aluminum alloy material for brazing in this embodiment is composed of the following mass percentages: La with a content of 6.0%, Ce with a content of 1.0%, Fe with a content of 0.5%, Mn with a content of 0.6%, Cr with a content of 0.4%, Mg with a content of 0.02%, Ti with a content of 0.2%, V with a content of 0.09%, B with a content of 0.05%, Si with a content of 0.09%, Cu with a content of 0.01%, and the balance being aluminum.

[0049] Preparation steps:

[0050] Step 1: According to the above mass percentages, add industrial pure aluminum ingots into a crucible resistance furnace for heating. Heat to 720 - 750 °C until the pure aluminum ingots are completely melted, and then successively add other components except aluminum element in the preset composition, that is, add other elemental components except aluminum element in the above mass percentage composition to obtain aluminum alloy liquid.

[0051] Step 2: Press the sodium-free aluminum alloy refining agent ZS-AJ6 into the aluminum alloy through a degassing machine for refining, and degas for 20 min to remove the gas in the aluminum liquid;

[0052] Step 3: Detect whether the composition of the effective aluminum alloy liquid meets the usage standard. If so, proceed to Step 4; if not, the mass percentage of a certain original element in the aluminum alloy liquid does not reach the above preset mass percentage, and additional mass percentages of elements need to be added to adjust the mass percentage of this element in the effective aluminum alloy liquid so that the mass percentage of this element meets the usage standard, that is, reaches the preset mass percentage.

[0053] Step 4: Detect the gas content through a hydrogen detector, and when the gas content reaches below 0.15 mL / 100 g, carry out die-casting forming through a high-pressure die-casting device. If the gas content does not meet the standard, continue the refining and degassing in Step 2.

[0054] Step 5: Use a 280T die-casting machine for die-casting. The die-casting temperature is 720 °C, the mold cavity vacuum degree is 35 mBar, the casting pressure is 31.5 MPa, the injection speed is 2.5 m / s, the mold temperature is 130 °C, and the aluminum alloy liquid temperature is 690 °C to obtain the aluminum alloy material for brazing. Its 1000 - fold metallographic structure diagram is as Figure 1 shown, and its 100 - fold metallographic structure diagram of the brazing weld with AA3003 / 4045 aluminum plate is as Figure 2 shown, which shows the mutual relationship among the casting 1, the weld 2, and the AA3003 / 4045 aluminum plate 3.

[0055] Example 2

[0056] The difference from Example 1 is that the aluminum alloy material for brazing is composed of the following mass percentages: La with a content of 6.0%, Ce with a content of 2.0%, Fe with a content of 0.5%, Mn with a content of 0.6%, Cr with a content of 0.4%, Mg with a content of 0.15%, Ti with a content of 0.2%, V with a content of 0.1%, B with a content of 0.06%, Si with a content of 0.09%, Cu with a content of 0.01%, and the balance is aluminum, and finally the aluminum alloy material for brazing is obtained.

[0057] Example 3

[0058] The difference from Example 1 is that the aluminum alloy material for brazing is composed of the following mass percentages: La with a content of 6.0%, Ce with a content of 3.0%, Fe with a content of 0.5%, Mn with a content of 0.6%, Cr with a content of 0.4%, Mg with a content of 0.02%, Ti with a content of 0.2%, V with a content of 0.05%, B with a content of 0.05%, Si with a content of 0.09%, Cu with a content of 0.01%, and the balance is aluminum, and finally the aluminum alloy material for brazing is obtained.

[0059] Example 4

[0060] The difference from Example 1 is that the aluminum alloy material for brazing is composed of the following mass percentages: La with a content of 6.0%, Ce with a content of 1.0%, Fe with a content of 0.5%, Mn with a content of 1.0%, Cr with a content of 0.4%, Mg with a content of 0.02%, Ti with a content of 0.2%, V with a content of 0.12%, B with a content of 0.05%, Si with a content of 0.09%, Cu with a content of 0.01%, and the balance is aluminum, and finally the aluminum alloy material for brazing is obtained.

[0061] Example 5

[0062] The difference from Example 1 is that the aluminum alloy material for brazing is composed of the following mass percentages: La with a content of 6.0%, Ce with a content of 2.0%, Fe with a content of 0.5%, Mn with a content of 1.0%, Cr with a content of 0.4%, Mg with a content of 0.15%, Ti with a content of 0.2%, V with a content of 0.10%, B with a content of 0.06%, Si with a content of 0.09%, Cu with a content of 0.01%, and the balance is aluminum, and finally the aluminum alloy material for brazing is obtained.

[0063] Example 6

[0064] The difference from Example 1 is that the aluminum alloy material for brazing is composed of the following mass percentages: La with a content of 6.0%, Ce with a content of 3.0%, Fe with a content of 0.5%, Mn with a content of 1.0%, Cr with a content of 0.4%, Mg with a content of 0.35%, Ti with a content of 0.2%, V with a content of 0.10%, B with a content of 0.05%, Si with a content of 0.09%, Cu with a content of 0.01%, and the balance being aluminum, and finally the aluminum alloy material for brazing is obtained.

[0065] Example 7

[0066] The difference from Example 4 is that the content of Fe is 0.8% and the content of Mn is 1.0%, and finally the aluminum alloy material for brazing is obtained.

[0067] Example 8

[0068] The difference from Example 4 is that the content of Fe is 0.4% and the content of Mn is 1.0%, and finally the aluminum alloy material for brazing is obtained.

[0069] Example 9

[0070] The difference from Example 4 is that the content of Fe is 1.2% and the content of Mn is 1.0%, and finally the aluminum alloy material for brazing is obtained.

[0071] Example 10

[0072] The difference from Example 4 is that the die-casting temperature is 710 °C, and finally the aluminum alloy material for brazing is obtained.

[0073] Example 11

[0074] The difference from Example 4 is that the die-casting temperature is 730 °C, and finally the aluminum alloy material for brazing is obtained.

[0075] Example 12

[0076] The difference from Example 4 is that the die-casting temperature is 700 °C, and finally the aluminum alloy material for brazing is obtained.

[0077] Comparative Example 1

[0078] The difference from Example 4 is that the aluminum alloy material for brazing is composed of the following mass percentages: La with a content of 4.0%, Ce with a content of 2%, Fe with a content of 2.0%, Mn with a content of 0.4%, Cr with a content of 1.0%, Mg with a content of 0.15%, Ti with a content of 0.1%, V with a content of 0.12%, B with a content of 0.05%, Si with a content of 0.09%, Cu with a content of 0.02%, and the balance being aluminum, and finally the aluminum alloy material for brazing is obtained. The solidus temperature of the aluminum alloy material for brazing is 615 °C.

[0079] In the aluminum alloy materials prepared in the above-mentioned examples and comparative examples, the proportion of Al 11 The proportions of RE3 phase, Al6Mn phase and Al7Cr phase are shown in Table 1.

[0080] Table 1

[0081]

[0082]

[0083] After wire cutting the test pieces of the aluminum alloy materials prepared in the above-mentioned examples and comparative examples according to the GBT228 standard, performance tests of tensile strength, yield strength, elongation at break and electrical conductivity were carried out, and the test results are shown in Table 2.

[0084] Table 2

[0085] Example / Comparative Example Tensile Strength (MPa) Yield Strength (MPa) Elongation at Break (%) Conductivity (ms / m) Example 1 180.7 80.2 19.1 16.7 Example 2 188.1 84.4 13.4 16.3 Example 3 198.5 93.8 10.0 16.0 Example 4 214.8 102.4 10.3 13.3 Example 5 219.6 102.9 10.4 13.28 Example 6 223.8 104.0 7.8 13.14 Example 7 210.6 103.2 8.8 13.0 Example 8 211.5 100.8 11.0 13.8 Example 9 208.9 100.6 7.7 14.0 Example 10 208.6 100.6 9.9 13.6 Example 11 209.5 103.3 10.3 14.1 Example 12 213.6 106.8 10.5 13.8 Comparative Example 1 180.3 81.4 4.0 16.6

[0086] Through the gas shielded welding process, the brazing feasibility test was carried out on the aluminum alloy materials prepared in the above-mentioned examples and comparative examples:

[0087] The specific brazing process includes: baking treatment (baking at 550°C for 1 h), spraying brazing flux, degreasing, drying, preheating, brazing, and cooling. The brazing flux was sprayed onto the AA3003 / 4045 aluminum plate through a brazing flux spraying device, degreasing was carried out in a furnace cavity at 110°C, then drying was carried out at 290°C, preheating was carried out in a furnace cavity at 560°C. Compared with the brazing temperature of 630°C for conventional brazing, this material was brazed in a furnace cavity at 610°C. On the premise of meeting the brazing requirements, the brazing temperature was reduced as much as possible to reduce the diffusion and corrosion of the weld microstructure and improve the weld strength. Finally, after water cooling or air cooling, the brazing process was completed. It should be noted that due to the special properties of this material, the oxygen and moisture content in the furnace cavity should be controlled. The protective atmosphere requires high-purity nitrogen, the oxygen content in the furnace cavity should be less than 20 ppm, and the nitrogen dew point should be controlled below -40°C. Performance tests of tensile strength, yield strength, elongation at break and electrical conductivity were carried out on the brazed aluminum alloy materials, and the test results are shown in Table 3.

[0088] Table 3

[0089] Example / Comparative Example Tensile Strength (MPa) Yield Strength (MPa) Elongation at Break (%) Conductivity (ms / m) Example 1 121.3 52.7 20.0 15.6 Example 2 132.4 59.3 27.8 15.1 Example 3 134.35 59.3 26.0 14.6 Example 4 141.2 66.1 22.9 12.5 Example 5 152.4 71.5 21.7 12.4 Example 6 164.8 76.7 19.8 11.7 Example 7 135.8 60.2 23.0 11.8 Example 8 140.8 63.1 20.3 12.6 Example 9 140.1 60.0 17.0 13.0 Example 10 133.8 57.0 20.8 11.9 Example 11 136.9 58.8 19.7 12.7 Example 12 141.7 61.9 21.0 12.4 Comparative Example 1 - - - -

[0090] The 100-fold metallographic structure diagrams of the brazed aluminum alloy materials and the brazed welds of AA3003 / 4045 aluminum plates in Examples 1-12 in Table 3 above are compared with Figure 2Similarly, it indicates that the aluminum alloy materials for brazing in Examples 1-12 have extremely low gas content and relatively high solid-liquid phase temperatures, and there are no obvious defects during high-temperature brazing. In addition, the weld microstructure forms a good Al-Si eutectic structure, which can improve the strength of the weld. At the same time, the grain size in the diffusion area of the weld has no abnormally large coarsening and segregation, indicating that the aluminum alloy materials for brazing in this application have good weldability and meet the design requirements.

[0091] For the aluminum alloy material for brazing obtained in Comparative Example 1, due to the low proportion of Al 11 RE3 phase in it, its tensile strength is low, the elongation at break and the solidus temperature are too low, so that it cannot be used as an alloy material for brazing process.

[0092] From the above description, it can be seen that the above embodiments of the present invention achieve the following technical effects:

[0093] Adding rare earth metal element RE to the aluminum alloy material for brazing helps to form a high eutectic point and high-temperature stable phases, thus forming a framework of aluminum alloy material system that can be brazed; adding Fe, Mn and Cr elements to the aluminum alloy material for brazing is beneficial to improving the anti-sticking property during die-casting; adding Mg element helps to improve the solution strengthening effect; adding Ti, V and B elements is beneficial to achieving tissue uniformity and preventing segregation; by controlling the content of each element within the above range, especially by controlling the content of rare earth metal element RE, the present invention enhances the synergistic cooperation among various elements, making the structure of the aluminum alloy material uniform and the grains fine, and having good castability, fluidity, hot cracking resistance and weldability.

[0094] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. An aluminum alloy material for brazing, characterized in that, By mass percentage, the aluminum alloy material for brazing comprises: rare earth metal element RE with a content of 3.0 - 12.0%, Fe with a content of 0.06 - 0.85%, Mn with a content of 0.5 - 1.2%, Cr with a content of 0.1 - 0.5%, Mg with a content of 0.02 - 0.5%, Ti with a content of 0.1 - 0.2%, V with a content of 0.02 - 0.2%, B with a content of 0.02 - 0.1%, Si with a content ≤ 0.15%, Cu with a content ≤ 0.02%, the balance being Al and inevitable impurities, and the content of each single impurity element ≤ 0.05%; Among them, the solidus temperature of the aluminum alloy material for brazing ≥ 625 °C.

2. The aluminum alloy material for brazing according to claim 1, characterized in that, In the aluminum alloy material for brazing, Al 11 The mass ratio of the AlRE3 phase is 11-15%, the mass ratio of the Al6Mn phase is 1-7%, and the mass ratio of the Al7Cr phase is 1-5%.

3. The aluminum alloy material for brazing according to claim 1 or 2, characterized in that The content of Fe is 0.35 - 0.8%, and / or the content of Mn is 0.65 - 1.2%; preferably, the mass ratio of Fe to Mn is 0.4 - 1.2:1, and further preferably 0.5 - 0.8:

1.

4. The aluminum alloy material for brazing according to any one of claims 1 to 3, characterized in that The rare earth metal element RE is La and Ce, and preferably the mass ratio of La to Ce is 2.0 - 6.0:

1.

5. The aluminum alloy material for brazing according to any one of claims 1 to 4, characterized in that The yield strength of the aluminum alloy material for brazing > 80 MPa, the fracture elongation rate > 7.0%, the tensile strength > 180 MPa, and the electrical conductivity ≥ 13.0 ms / s.

6. A method for preparing the aluminum alloy material for brazing according to any one of claims 1 to 5, characterized in that, The preparation method comprises: Step S1, melting rare earth metal element RE, Fe, Mn, Cr, Mg, Ti, V, B, Si, and Cu in the form of alloys or single substances respectively with aluminum ingots to obtain aluminum alloy liquid; Step S2, degassing the aluminum alloy liquid to obtain degassed aluminum alloy liquid; Step S3, die-casting the degassed aluminum alloy liquid to obtain the aluminum alloy material for brazing.

7. The preparation method according to claim 6, characterized in that, In the step S3, the die-casting temperature is 710 - 730 °C, and / or the vacuum degree of the die-casting mold cavity is 35 - 50 mBar, and / or the die-casting pressure is 26.5 - 36.5 MPa, and / or the die-casting injection speed is 2 - 3 m / s, and / or the die-casting mold temperature is 120 - 140 °C, and / or the temperature of the degassed aluminum alloy liquid is 680 - 700 °C.

8. The preparation method according to claim 6 or 7, characterized in that, The melting temperature is 690 - 750 °C, preferably 720 - 750 °C.

9. The preparation method according to any one of claims 6 to 8, characterized in that, The degassing is chemical degassing. Preferably, the reagent used for the chemical degassing is a sodium-free refining agent for aluminum alloy, and / or the degassing time is 10 - 20 min, and / or the degassing temperature is 700 - 720 °C, and / or the gas content of the degassed aluminum alloy liquid < 0.15 mL / 100 g.

10. The brazing process of the aluminum alloy material for brazing according to any one of claims 1 to 5, the brazing process comprising: For the steps of spraying flux, degreasing, drying, preheating, brazing, and cooling the aluminum alloy material for brazing in sequence, it is characterized in that, before the step of spraying flux, the aluminum alloy material for brazing is subjected to baking treatment to obtain the aluminum alloy material after brazing; Preferably, the baking treatment temperature is 550 - 610 °C, and / or the baking treatment time is 1 - 3 h.

Images