A brazing aluminum alloy and its preparation method and brazing process

Abstract

The invention discloses a brazing aluminum alloy, a preparation method thereof, and a brazing process thereof. The brazing aluminum alloy comprises the following materials: Mn: 1.0-2.0 wt%, Fe: 0.6-1.0 wt%, Mg: 0.25-0.5 wt%, Mo+W+Co: 0.1-0.3 wt%, Zr: 0.05-0.3 wt%, Si: 0.3-1.3 wt%, Sr: 0.015-0.025 wt%, Zn: 0.5-1.5 wt%, Ni≤0.5 wt% and Cu≤0.5 wt%, with the remainder being Al and impurities, wherein the impurities The total content is not more than 0.15wt%; the present invention has a simple structure and a reasonable design. By regulating the elements and optimizing the smelting preparation process, the solid-liquid phase line of the aluminum alloy material is improved. At the same time, the wettability and matching between the die-cast material and the solder are combined to develop a die-cast aluminum alloy material suitable for solder spreading and wetting. The appropriate welding process is matched according to the developed material properties to improve the welding quality of the product. Compared with the existing technology, it has the advantages of low cost, corrosion resistance and high welding quality. At the same time, combined with the heat treatment strengthening process of the material, the problem of rapid deterioration of the product performance after brazing is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of brazable die-cast aluminum alloys, and in particular to a brazable aluminum alloy and a

[0002] Preparation method and brazing process. Background Art

[0003] The thermal management system of new energy vehicles is developing in the direction of integration, which helps to improve the performance and efficiency of the entire vehicle. At present, the more mature solution adopted by the automotive thermal management system is 6063 forging and extrusion. The blanks are formed by forging and extrusion, and need to undergo multiple rounds of machining, resulting in high machining costs. In addition, the melting point of existing die-cast aluminum alloys is lower than 600℃ and cannot be used for brazing. If the welding method is changed to laser welding, stir friction welding, etc., the sealing effect and welding yield of the product are not high. Summary of the Invention

[0004] The object of the present invention is to provide a brazing aluminum alloy and a preparation method and a brazing process thereof, so as to solve the problems raised in the above background technology.

[0005] To achieve the above-mentioned object, the present invention provides the following technical solution: A brazable aluminum alloy, comprising the following materials: Mn: 1.0-2.0wt%, Fe: 0.6-1.0wt%, Mg: 0.25-0.5wt%, Mo+W+Co: 0.1-0.3wt%, Zr: 0.05-0.3wt%, Si: 0.3-1.3wt%, Sr: 0.015-0.025wt%, Zn: 0.5-1.5wt%, Ni≤0.5wt% and Cu≤0.5wt%; the balance is Al and impurities, wherein the total impurity content is not more than 0.15wt%.

[0006] Preferably, the mass fraction relationship between Si, Mo, W and Co is:

[0007] 3≤Si / (Mo+W+Co)≤8;

[0008] The mass fraction relationship between Mo, W and Co is:

[0009] Mo:W:Co=4:2:1;

[0010] The mass fraction relationship between Mn, Fe and Zr is:

[0011] 6≤(Mn+Fe) / Zr≤20.

[0012] The present invention also provides a preparation and brazing process of a brazable aluminum alloy, the process specifically comprising the following steps:

[0013] S1. preparing an alloy melt;

[0014] S2, refining the alloy melt to complete degassing and impurity removal;

[0015] S3, feeding the alloy melt into the die-casting machine to obtain the product blank after die-casting, cleaning it, and waiting for welding;

[0016] S4. Pickling the die casting to be welded and the deformed cover plate to remove foreign matter on the surface, and spraying brazing flux to remove the surface oxide layer;

[0017] S5. Assemble the casting and the deformed aluminum cover plate by riveting. The clamping force is 2KN and the pressure holding time is 5-8s. After the assembly is completed, clean the excess brazing flux on the surface.

[0018] S6. Place the product into a brazing furnace for welding;

[0019] S7. Heat treat the product.

[0020] Preferably, the step S1 specifically includes the following steps:

[0021] a1. Weigh the ingredients according to the designed material formula and prepare the raw materials;

[0022] a2. Preheat the smelting ladle. The preheating temperature is set to 350℃ and the preheating time is 2h.

[0023] a3. After preheating, control the melting furnace temperature to 780-800℃, add A00 into the melting furnace and melt it. After melting, take TP sample and confirm the material composition;

[0024] a4. Add silicon, magnesium ingot, aluminum manganese, zinc ingot, aluminum zirconium, aluminum molybdenum, aluminum strontium and other intermediate alloys and stir evenly to obtain an alloy melt.

[0025] Preferably, the step S2 specifically includes the following steps:

[0026] b1. Introduce nitrogen into the alloy melt as a protective gas at a rate of 0.15-6 L / min;

[0027] b2. Add RJ-01 refining agent, set the refining time to 20-25min, and the amount of solid refining agent added is 0.2%-0.5% of the alloy melt mass;

[0028] b3. The alloy melt is subjected to GBF rotary degassing in batches.

[0029] Preferably, the step S3 specifically includes the following steps:

[0030] c1. The alloy melt is fed into the side furnace of the die casting machine and allowed to stand for 20 minutes;

[0031] c2. Carry out slag removal;

[0032] c3. After the aluminum liquid temperature reaches the set temperature, die casting is performed to obtain the product blank;

[0033] c4. The die-cast product is machined, pickled and high-pressure cleaned to obtain the finished product, ready for welding.

[0034] Preferably, step S6 specifically includes the following steps:

[0035] d1. Set the oxygen content in the furnace to less than 100 ppm, and heat the brazing furnace to 300°C at a rate of 10°C / min and keep it at that temperature for 90 minutes;

[0036] d2. Heat the brazing furnace to 520°C and hold for 75 minutes at a heating rate of 8°C / min.

[0037] d3. Raise the temperature of the brazing furnace to 600°C and maintain it for 20 min at a heating rate of 5°C / min;

[0038] d4, heat the brazing furnace to 615℃ and hold for 10 min at a heating rate of 3℃ / min;

[0039] d5. After the solder melts and forms an intermediate compound with the base material, control the furnace temperature to decrease to 200°C at a rate of 10°C / min and cool it down. Take out the soldered sample.

[0040] Preferably, the step S7 specifically includes the following steps:

[0041] e1. Take the product out of the brazing furnace at 200°C and place it in a solution furnace at 180°C. Heat it up to 520°C at a heating rate of 5°C / min for solution treatment. The solution time is 4 hours.

[0042] e2. Place the product in 50℃ water for cooling for 10-30s;

[0043] e3. Place the product in an aging furnace for aging treatment. The aging temperature is 160°C, the aging time is 5 hours, and the cooling method is air cooling.

[0044] Preferably, the forming process in step a4 is high pressure casting, the aluminum liquid temperature is set to 700-730° C., the mold temperature is set to 200-250° C., the casting pressure is set to 80-120 MPa, and the speed is set to 0.5 m / s.

[0045] Preferably, in step b3, the ultrasonic treatment parameters are set to ultrasonic power of 150KW, frequency of 15KHz, ultrasonic time of 10min, and standing time of 2min.

[0046] Compared with the prior art, the present invention has the following beneficial effects:

[0047] The present invention discloses a brazing aluminum alloy, a preparation method thereof, and a brazing process. The present invention improves the solidus and liquidus phases of the aluminum alloy material by regulating elements and optimizing the smelting preparation process. At the same time, the wettability and matching between the die-cast material and the solder are combined to develop a die-cast aluminum alloy material suitable for solder spreading and wetting. The appropriate welding process is matched according to the characteristics of the developed material, thereby improving the welding quality of the product. Compared with the existing technology, the present invention has the advantages of low cost, corrosion resistance, and high welding quality. At the same time, combined with the heat treatment strengthening process of the material, the problem of rapid deterioration of product performance after brazing is solved.

[0048] In this invention, aluminum alloy products are removed from the welder after cooling to 200°C, rather than cooling to room temperature, for subsequent heat treatment and strengthening. This utilizes the heat left over from the welding process to further increase the temperature, ensuring uniform heating of the material within the temperature field and reducing deformation of thin-walled parts under thermal stress. Further heat treatment and strengthening can also increase the product's detonation pressure. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 Schematic diagram of the microstructure of the present invention;

[0050] Figure 2 DSC curve diagram of the material of the present invention;

[0051] Figure 3 This is a comparison chart of the corrosion resistance of the aluminum alloy of the present invention and Al-Ni-Fe based materials;

[0052] Figure 4 Implement the state diagram for Comparative Example 2. DETAILED DESCRIPTION

[0053] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0054] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0055] In the description of this patent, it should be noted that, unless otherwise expressly specified or limited, the terms "installed," "connected," and "disposed" should be understood broadly. For example, they can refer to fixed connection or disposition, detachable connection or disposition, or integrated connection or disposition. Those skilled in the art will understand the specific meanings of the above terms in this patent based on the specific circumstances.

[0056] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, "several" means two or more, unless otherwise specifically defined.

[0057] Example 1

[0058] The present invention provides a technical solution for a brazable aluminum alloy, comprising the following materials: Mn 1.3wt%, Fe 0.6wt%, Mg 0.3wt%, Zr 0.18wt%, Si 0.58wt%, Sr 0.015wt%, Zn 0.55wt%, Ni 0.003wt%, Cu 0.12wt%, Mo 0.057wt%, W 0.028wt% and Co 0.0142wt%, with the remainder being Al and impurities, wherein the total impurity content is less than 0.2wt%, and the mass fraction relationship between Si, Mo, W and Co is Si / (Mo +W+Co) is 5.8, the mass fraction relationship between Mo, W and Co is Mo:W:Co=4:2:1, and (Mn+Fe) / Zr is 10.5. An appropriate amount of Mo / W / Co is introduced into the aluminum matrix to increase the solid-liquid phase temperature of the aluminum alloy to meet the high-temperature brazing requirements of the product. At the same time, the high-temperature dispersion strengthening phase formed makes the performance attenuation of the material after brazing within 3%; compared with the diffusion of a single element, the combined diffusion of multi-component high-melting-point elements reduces the activation energy of element diffusion during brazing, thereby being more conducive to the element diffusion between the base material and the solder layer, and obtaining a higher quality weld joint.

[0059] The present invention provides a preparation method and brazing process technology solution for a brazable aluminum alloy. The preparation method and brazing process specifically include the following steps:

[0060] S1. preparing an alloy melt;

[0061] a1. Weigh the ingredients according to the designed material formula and prepare the raw materials;

[0062] a2. Preheat the melting ladle. The preheating temperature is set to 350℃ and the preheating time is 2 hours to ensure the temperature uniformity of the melting ladle.

[0063] a3. After preheating, control the melting furnace temperature to 780-800℃, add A00 into the melting furnace and melt it. After melting, take TP sample and confirm the material composition;

[0064] a4. Add silicon, magnesium ingot, aluminum manganese, zinc ingot, aluminum zirconium, aluminum molybdenum, aluminum strontium and other master alloys and stir them evenly to obtain an alloy melt. The forming process is high-pressure casting, with the aluminum liquid temperature set to 700-730℃, the mold temperature set to 200-250℃, the casting pressure set to 80-120MPa, and the speed set to 0.5m / s;

[0065] S2, refining the alloy melt to complete degassing and impurity removal;

[0066] b1. Introduce nitrogen into the alloy melt as a protective gas at a rate of 0.15-6 L / min;

[0067] b2. Add RJ-01 refining agent, set the refining time to 20-25min, and the amount of solid refining agent added is 0.2%-0.5% of the alloy melt mass;

[0068] b3. Ultrasonic degassing was performed on the alloy melt in batches to further reduce the gas content in the aluminum liquid. The aluminum liquid temperature was 730°C, and the ultrasonic treatment parameters were set as ultrasonic power 150KW, frequency 15KHz, ultrasonic time 10 minutes, and standing time 2 minutes.

[0069] S3, feeding the alloy melt into the die-casting machine to obtain the product blank after die-casting, cleaning it, and waiting for welding;

[0070] c1. The alloy melt is fed into the side furnace of the die casting machine and allowed to stand for 20 minutes;

[0071] c2. Carry out slag removal;

[0072] c3. After the aluminum liquid temperature reaches the set temperature, die casting is performed to obtain the product blank;

[0073] c4. The die-cast product is machined, pickled and high-pressure cleaned to obtain the finished product, ready for welding;

[0074] S4. Pickle the die casting and the deformed cover plate to be welded, remove foreign matter on the surface, spray brazing flux to remove the surface oxide layer, and ensure good wettability of the welding surface;

[0075] S5. Assemble the casting and the deformed aluminum cover plate by riveting. The clamping force is 2KN and the pressure holding time is 5-8s. After the assembly is completed, the excess flux on the surface is cleaned and the mold is loaded to maintain the stability of the applied force.

[0076] S6. Place the product into a brazing furnace for welding;

[0077] d1. Set the oxygen content in the furnace to less than 100 ppm, and heat the brazing furnace to 300°C at a rate of 10°C / min and keep it at that temperature for 90 minutes;

[0078] d2. Heat the brazing furnace to 520°C and hold for 75 minutes at a heating rate of 8°C / min.

[0079] d3. Raise the temperature of the brazing furnace to 600°C and maintain it for 20 min at a heating rate of 5°C / min;

[0080] d4, heat the brazing furnace to 615℃ and hold for 10 min at a heating rate of 3℃ / min;

[0081] d5. After the solder melts and forms an intermediate compound with the base material, the furnace temperature is controlled to cool down to 200℃ at a rate of 10℃ / min, not to room temperature, for subsequent heat treatment and strengthening of products. The welded samples are taken out and T6 treatment is performed on the products after welding. The cover is also strengthened to improve the pressure resistance of the product and avoid deformation of the cover caused by softening at high temperature.

[0082] S7, heat treating the product;

[0083] e1. Take the product out of the brazing furnace at 200°C and place it in a solution furnace at 180°C. Heat it up to 520°C at a heating rate of 5°C / min for solution treatment. The solution time is 4 hours.

[0084] e2. Place the product in 50℃ water for cooling for 10-30s;

[0085] e3. Place the product in an aging furnace for aging treatment. The aging temperature is 160°C and the aging time is

[0086] 5h, cooling method is air cooling;

[0087] The final aluminum alloy material properties are: melting point 649℃, tensile strength 218MPa, yield strength 158MPa, elongation at break 6%, and corrosion rate 0.0013mm / a.

[0088] Example 2

[0089] The present invention provides a technical solution for a brazing aluminum alloy, comprising the following materials: 1.44 wt% Mn, 0.73 wt% Fe, 0.29 wt% Mg, 0.13 wt% Zr, 0.7 wt% Si, 0.018 wt% Sr, 0.58 wt% Zn, 0.007 wt% Ni, 0.09 wt% Cu, 0.085 wt% Mo, 0.042 wt% W, and 0.021 wt% Co, with the remainder being Al and impurities, wherein the total impurity content is less than 0.2 wt%, the mass fraction relationship among Si, Mo, W, and Co is Si / (Mo+W+Co), which is 4.66, the mass fraction relationship among Mo, W, and Co is Mo:W:Co=4:2:1, and (Mn+Fe) / Zr is 16.6.

[0090] The present invention provides a preparation method and brazing process technology solution for a brazable aluminum alloy. The preparation method and brazing process specifically include the following steps:

[0091] S1. preparing an alloy melt;

[0092] a1. Weigh the ingredients according to the designed material formula and prepare the raw materials;

[0093] a2. Preheat the melting ladle. The preheating temperature is set to 350℃ and the preheating time is 2 hours to ensure the temperature uniformity of the melting ladle.

[0094] a3. After preheating, control the melting furnace temperature to 780-800℃, add A00 into the melting furnace and melt it. After melting, take TP sample and confirm the material composition;

[0095] a4. Add silicon, magnesium ingot, aluminum manganese, zinc ingot, aluminum zirconium, aluminum molybdenum, aluminum strontium and other master alloys and stir them evenly to obtain an alloy melt. The forming process is high-pressure casting, with the aluminum liquid temperature set to 700-730℃, the mold temperature set to 200-250℃, the casting pressure set to 80-120MPa, and the speed set to 0.5m / s;

[0096] S2, refining the alloy melt to complete degassing and impurity removal;

[0097] b1. Introduce nitrogen into the alloy melt as a protective gas at a rate of 0.15-6 L / min;

[0098] b2. Add RJ-01 refining agent, set the refining time to 20-25min, and the amount of solid refining agent added is 0.2%-0.5% of the alloy melt mass;

[0099] b3. GBF rotary degassing was performed on the alloy melt in batches to further reduce the gas content in the aluminum liquid. The aluminum liquid temperature was 730°C, and the ultrasonic treatment parameters were set as ultrasonic power 150KW, frequency 15KHz, ultrasonic time 10min, and standing time 2min.

[0100] S3, feeding the alloy melt into the die-casting machine to obtain the product blank after die-casting, cleaning it, and waiting for welding;

[0101] c1. The alloy melt is fed into the side furnace of the die casting machine and allowed to stand for 20 minutes;

[0102] c2. Carry out slag removal;

[0103] c3. After the aluminum liquid temperature reaches the set temperature, die casting is performed to obtain the product blank;

[0104] c4. The die-cast product is machined, pickled and high-pressure cleaned to obtain the finished product, ready for welding;

[0105] S4. Pickle the die casting and the deformed cover plate to be welded, remove foreign matter on the surface, spray brazing flux to remove the surface oxide layer, and ensure good wettability of the welding surface;

[0106] S5. Assemble the casting and the deformed aluminum cover plate by riveting. The clamping force is 2KN and the pressure holding time is 5-8s. After the assembly is completed, the excess flux on the surface is cleaned and the mold is loaded to maintain the stability of the applied force.

[0107] S6. Place the product into a brazing furnace for welding;

[0108] d1. Set the oxygen content in the furnace to less than 100 ppm, and heat the brazing furnace to 300°C at a rate of 10°C / min and keep it at that temperature for 90 minutes;

[0109] d2. Heat the brazing furnace to 520°C and hold for 75 minutes at a heating rate of 8°C / min.

[0110] d3. Raise the temperature of the brazing furnace to 600°C and maintain it for 20 min at a heating rate of 5°C / min;

[0111] d4, heat the brazing furnace to 615℃ and hold for 10 min at a heating rate of 3℃ / min;

[0112] d5. After the solder melts and forms an intermediate compound with the base material, the furnace temperature is controlled to cool down to 200℃ at a rate of 10℃ / min, not to room temperature, for subsequent heat treatment and strengthening of products. The welded samples are taken out and T6 treatment is performed on the products after welding. The cover is also strengthened to improve the pressure resistance of the product and avoid deformation of the cover caused by softening at high temperature.

[0113] S7, heat treating the product;

[0114] e1. Take the product out of the brazing furnace at 200°C and place it in a solution furnace at 180°C. Heat it up to 520°C at a heating rate of 5°C / min for solution treatment. The solution time is 4 hours.

[0115] e2. Place the product in 50℃ water for cooling for 10-30s;

[0116] e3. Place the product in an aging furnace for aging treatment. The aging temperature is 160°C and the aging time is

[0117] 5h, cooling method is air cooling;

[0118] The final aluminum alloy material properties are: melting point of 648.7℃, tensile strength of 222MPa, yield strength of 146MPa, elongation at break of 6.8%, and corrosion rate of 0.0015mm / a.

[0119] Example 3

[0120] The present invention provides a technical solution for a brazing aluminum alloy, comprising the following materials: 1.7 wt% Mn, 0.8 wt% Fe, 0.33 wt% Mg, 0.16 wt% Zr, 0.9 wt% Si, 0.023 wt% Sr, 0.7 wt% Zn, 0.003 wt% Ni, 0.18 wt% Cu, 0.103 wt% Mo, 0.051 wt% W, and 0.026 wt% Co, with the remainder being Al and impurities, wherein the total impurity content is less than 0.2 wt%, the mass fraction relationship among Si, Mo, W, and Co is Si / (Mo+W+Co)=5.0, the mass fraction relationship among Mo, W, and Co is Mo:W:Co=4:2:1, and (Mn+Fe) / Zr is 15.625.

[0121] The present invention provides a preparation method and brazing process technology solution for a brazable aluminum alloy. The preparation method and brazing process specifically include the following steps:

[0122] S1. preparing an alloy melt;

[0123] a1. Weigh the ingredients according to the designed material formula and prepare the raw materials;

[0124] a2. Preheat the melting ladle. The preheating temperature is set to 350℃ and the preheating time is 2 hours to ensure the temperature uniformity of the melting ladle.

[0125] a3. After preheating, control the melting furnace temperature to 780-800℃, add A00 into the melting furnace and melt it. After melting, take TP sample and confirm the material composition;

[0126] a4. Add silicon, magnesium ingot, aluminum manganese, aluminum zirconium, aluminum molybdenum and aluminum strontium master alloy and stir evenly to obtain an alloy melt. The forming process is high-pressure casting, with the aluminum liquid temperature set to 700-730°C, the mold temperature set to 200-250°C, the casting pressure set to 80-120 MPa, and the casting speed set to 4.5 m / s;

[0127] S2, refining the alloy melt to complete degassing and impurity removal;

[0128] b1. Introduce nitrogen into the alloy melt as a protective gas at a rate of 0.15-6 L / min;

[0129] b2. Add RJ-01 refining agent, set the refining time to 20-25min, and the amount of solid refining agent added is 0.2%-0.5% of the alloy melt mass;

[0130] b3. Ultrasonic degassing was performed on the alloy melt in batches to further reduce the gas content in the aluminum liquid. The aluminum liquid temperature was 730°C, and the ultrasonic treatment parameters were set as ultrasonic power 150KW, frequency 15KHz, ultrasonic time 10 minutes, and standing time 2 minutes.

[0131] S3, feeding the alloy melt into the die-casting machine to obtain the product blank after die-casting, cleaning it, and waiting for welding;

[0132] c1. The alloy melt is fed into the side furnace of the die casting machine and allowed to stand for 20 minutes;

[0133] c2. Carry out slag removal;

[0134] c3. After the aluminum liquid temperature reaches the set temperature, die casting is performed to obtain the product blank;

[0135] c4. The die-cast product is machined, pickled and high-pressure cleaned to obtain the finished product, ready for welding;

[0136] S4. Pickle the die casting and the deformed cover plate to be welded, remove foreign matter on the surface, spray brazing flux to remove the surface oxide layer, and ensure good wettability of the welding surface;

[0137] S5. Assemble the casting and the cover plate 6063 by riveting. The clamping force is 2KN and the pressure holding time is 5-8s. After the assembly is completed, clean the excess flux on the surface and load the mold to maintain the stability of the applied force.

[0138] S6. Place the product into a brazing furnace for welding;

[0139] d1. Set the oxygen content in the furnace to less than 100 ppm, and heat the brazing furnace to 300°C at a rate of 10°C / min and keep it at that temperature for 90 minutes;

[0140] d2. Heat the brazing furnace to 520°C and hold for 75 minutes at a heating rate of 8°C / min.

[0141] d3. Raise the temperature of the brazing furnace to 600°C and maintain it for 20 min at a heating rate of 5°C / min;

[0142] d4, heat the brazing furnace to 615℃ and hold for 10 min at a heating rate of 3℃ / min;

[0143] d5. After the solder melts and forms an intermediate compound with the base material, the furnace temperature is controlled to cool down to 200℃ at a rate of 10℃ / min, not to room temperature, for subsequent heat treatment and strengthening of products. The welded samples are taken out and T6 treatment is performed on the products after welding. The cover is also strengthened to improve the pressure resistance of the product and avoid deformation of the cover caused by softening at high temperature.

[0144] S7, heat treating the product;

[0145] e1. Take the product out of the brazing furnace at 200°C and place it in a solution furnace at 180°C. Heat it up to 520°C at a heating rate of 5°C / min for solution treatment. The solution time is 4 hours.

[0146] e2. Place the product in 50℃ water for cooling for 10-30s;

[0147] e3. Place the product in an aging furnace for aging treatment. The aging temperature is 160°C and the aging time is

[0148] 5h, cooling method is air cooling;

[0149] The final aluminum alloy material properties are: melting point of 649.5℃, tensile strength of 235MPa, yield strength of 156MPa, elongation at break of 7.1%, and corrosion rate of 0.0014mm / a.

[0150] Comparative Example 1

[0151] A technical solution for a brazable aluminum alloy is provided: comprising the following materials: Mn 1.0wt%, Fe 0.8wt%, Mg 0.001wt%, Si 0.07wt%, Zn 0.018wt%, Ni 2.8wt%, Cr 0.35wt%, with the remainder being Al and impurities, wherein the total impurity content is less than 0.2wt%.

[0152] Provided are a preparation method and brazing process technology for a brazable aluminum alloy, the preparation method and brazing process specifically comprising the following steps:

[0153] S1. preparing an alloy melt;

[0154] a1. Weigh the ingredients according to the designed material formula and prepare the raw materials;

[0155] a2. Preheat the melting ladle. The preheating temperature is set to 350℃ and the preheating time is 2 hours to ensure the temperature uniformity of the melting ladle.

[0156] a3. After preheating, control the melting furnace temperature to 780-800℃, add A00 into the melting furnace and melt it. After melting, take TP sample and confirm the material composition;

[0157] a4. Add silicon, magnesium ingot, aluminum manganese, aluminum iron, aluminum nickel and aluminum chromium master alloy and stir evenly to obtain alloy melt. The forming process is high pressure casting, the aluminum liquid temperature is set to 700-730℃, the mold temperature is set to 200-250℃, the casting pressure is set to 80-120MPa, and the speed is set to 0.5m / s;

[0158] S2, refining the alloy melt to complete degassing and impurity removal;

[0159] b1. Introduce nitrogen into the alloy melt as a protective gas at a rate of 0.15-6 L / min;

[0160] b2. Add RJ-01 refining agent, set the refining time to 20-25min, and the amount of solid refining agent added is 0.2%-0.5% of the alloy melt mass;

[0161] b3. Ultrasonic degassing was performed on the alloy melt in batches to further reduce the gas content in the aluminum liquid. The aluminum liquid temperature was 730°C, and the ultrasonic treatment parameters were set as ultrasonic power 150KW, frequency 15KHz, ultrasonic time 10 minutes, and standing time 2 minutes.

[0162] S3, feeding the alloy melt into the die-casting machine to obtain the product blank after die-casting, cleaning it, and waiting for welding;

[0163] c1. The alloy melt is fed into the side furnace of the die casting machine and allowed to stand for 20 minutes;

[0164] c2. Carry out slag removal;

[0165] c3. After the aluminum liquid temperature reaches the set temperature, die casting is performed to obtain the product blank;

[0166] c4. The die-cast product is machined, pickled and high-pressure cleaned to obtain the finished product, ready for welding;

[0167] S4. Pickle the die casting and the deformed cover plate to be welded, remove foreign matter on the surface, spray brazing flux to remove the surface oxide layer, and ensure good wettability of the welding surface;

[0168] S5. Assemble the casting and the deformed aluminum cover plate by riveting. The clamping force is 2KN and the pressure holding time is 5-8s. After the assembly is completed, the excess flux on the surface is cleaned and the mold is loaded to maintain the stability of the applied force.

[0169] S6. Place the product into a brazing furnace for welding;

[0170] d1. Set the oxygen content in the furnace to less than 100 ppm, and heat the brazing furnace to 300°C at a rate of 10°C / min and keep it at that temperature for 90 minutes;

[0171] d2. Heat the brazing furnace to 520°C and hold for 75 minutes at a heating rate of 8°C / min.

[0172] d3. Raise the temperature of the brazing furnace to 600°C and maintain it for 20 min at a heating rate of 5°C / min;

[0173] d4, heat the brazing furnace to 615℃ and hold for 10 min at a heating rate of 3℃ / min;

[0174] d5. After the solder melts and forms an intermediate compound with the base material, the furnace temperature is controlled to cool down to 200℃ at a rate of 10℃ / min, not to room temperature, for subsequent heat treatment and strengthening of products. The welded samples are taken out and T6 treatment is performed on the products after welding. The cover is also strengthened to improve the pressure resistance of the product and avoid deformation of the cover caused by softening at high temperature.

[0175] S7, heat treating the product;

[0176] e1. Take the product out of the brazing furnace at 200°C and place it in a solution furnace at 180°C. Heat it up to 520°C at a heating rate of 5°C / min for solution treatment. The solution time is 4 hours.

[0177] e2. Place the product in 50℃ water for cooling for 10-30s;

[0178] e3. Place the product in an aging furnace for aging treatment. The aging temperature is 160°C and the aging time is

[0179] 5h, cooling method is air cooling.

[0180] Comparative Example 2

[0181] Provided is a technical solution for a brazing aluminum alloy: comprising the following materials: 1.4 wt% Mn, 0.78 wt% Fe, 0.32 wt% Mg, 1.3 wt% Si, 0.023 wt% Sr, 0.68 wt% Zn, 0.005 wt% Ni, 0.25 wt% Cu, 0.057 wt% Mo, 0.028 wt% W, and 0.0142 wt% Co, with the remainder being Al and impurities. The mass fraction relationships among Si, Mo, W, and Co are as follows: Si / (Mo+W+Co) is 13.0, and (Mn+Fe) / Zr is 12.82.

[0182] Provided are a preparation method and brazing process technology for a brazable aluminum alloy, the preparation method and brazing process specifically comprising the following steps:

[0183] S1. preparing an alloy melt;

[0184] a1. Weigh the ingredients according to the designed material formula and prepare the raw materials;

[0185] a2. Preheat the melting ladle. The preheating temperature is set to 350℃ and the preheating time is 2 hours to ensure the temperature uniformity of the melting ladle.

[0186] a3. After preheating, control the melting furnace temperature to 780-800℃, add A00 into the melting furnace and melt it. After melting, take TP sample and confirm the material composition;

[0187] a4. Add silicon, magnesium ingot, aluminum manganese, zinc ingot, aluminum zirconium, aluminum molybdenum, aluminum strontium and other master alloys and stir them evenly to obtain an alloy melt. The forming process is high-pressure casting, with the aluminum liquid temperature set to 700-730℃, the mold temperature set to 200-250℃, the casting pressure set to 80-120MPa, and the speed set to 0.5m / s;

[0188] S2, refining the alloy melt to complete degassing and impurity removal;

[0189] b1. Introduce nitrogen into the alloy melt as a protective gas at a rate of 0.15-6 L / min;

[0190] b2. Add RJ-01 refining agent, set the refining time to 20-25min, and the amount of solid refining agent added is 0.2%-0.5% of the alloy melt mass;

[0191] b3. Ultrasonic degassing was performed on the alloy melt in batches to further reduce the gas content in the aluminum liquid. The aluminum liquid temperature was 730°C, and the ultrasonic treatment parameters were set as ultrasonic power 150KW, frequency 15KHz, ultrasonic time 10 minutes, and standing time 2 minutes.

[0192] S3, feeding the alloy melt into the die-casting machine to obtain the product blank after die-casting, cleaning it, and waiting for welding;

[0193] c1. The alloy melt is fed into the side furnace of the die casting machine and allowed to stand for 20 minutes;

[0194] c2. Carry out slag removal;

[0195] c3. After the aluminum liquid temperature reaches the set temperature, die casting is performed to obtain the product blank;

[0196] c4. The die-cast product is machined, pickled and high-pressure cleaned to obtain the finished product, ready for welding;

[0197] S4. Pickle the die casting and the deformed cover plate to be welded, remove foreign matter on the surface, spray brazing flux to remove the surface oxide layer, and ensure good wettability of the welding surface;

[0198] S5. Assemble the casting and the cover plate 6063 by riveting. The clamping force is 2KN and the pressure holding time is 5-8s. After the assembly is completed, clean the excess flux on the surface and load the mold to maintain the stability of the applied force.

[0199] S6. Place the product into a brazing furnace for welding;

[0200] d1. Set the oxygen content in the furnace to less than 100 ppm, and heat the brazing furnace to 300°C at a rate of 10°C / min and keep it at that temperature for 90 minutes;

[0201] d2. Heat the brazing furnace to 520°C and hold for 75 minutes at a heating rate of 8°C / min.

[0202] d3. Raise the temperature of the brazing furnace to 600°C and maintain it for 20 min at a heating rate of 5°C / min;

[0203] d4, heat the brazing furnace to 615℃ and hold for 10 min at a heating rate of 3℃ / min;

[0204] d5. After the solder melts and forms an intermediate compound with the base material, the furnace temperature is controlled to cool down to 200℃ at a rate of 10℃ / min, not to room temperature, for subsequent heat treatment and strengthening of products. The welded samples are taken out and T6 treatment is performed on the products after welding. The cover is also strengthened to improve the pressure resistance of the product and avoid deformation of the cover caused by softening at high temperature.

[0205] S7, heat treating the product;

[0206] e1. Take the product out of the brazing furnace at 200°C and place it in a solution furnace at 180°C. Heat it up to 520°C at a heating rate of 5°C / min for solution treatment. The solution time is 4 hours.

[0207] e2. Place the product in 50℃ water for cooling for 10-30s;

[0208] e3. Place the product in an aging furnace for aging treatment. The aging temperature is 160°C, the aging time is 5 hours, and the cooling method is air cooling.

[0209] When the ratio of Si / (Mo+W+Co) in this comparative example exceeds the limit, the melting point of the material is only 615° C., and blistering and melting phenomena will occur during the brazing process, which cannot meet the product application requirements.

[0210]

[0211] Table 1 Components of different embodiments

[0212] Table 2 Performance of different embodiments

[0213]

[0214] With the vigorous development of new energy vehicles, the demand for lightweight is growing. Thinning the thickness of the brazed cover plate can bring advantages such as cost reduction and lightweight components. However, the cover plate has problems such as softening and deformation after brazing. In order to solve this problem, the present invention studies the heat treatment strengthening process of the product. After the welding is completed and the temperature in the furnace is cooled to 200℃, the product is taken out and transferred to the solid solution furnace.

[0215] The product was then heated to 520°C at a heating rate of 5°C / min for solution treatment for 4 hours. The product was then placed in 50°C water for cooling for 10-30 seconds. The product was then placed in an aging furnace for aging treatment at 160°C for 5 hours. The cooling method was air cooling. After the heat treatment strengthening process, the cover plate strength increased from 80MPa after brazing to 180MPa, and the product bursting pressure increased by 33%. The cover plate strength and bursting pressure under different heat treatment conditions are shown in Table 3 below. It can be seen from the table that the strengthening effect of the cover plate is not obvious when the heating temperature is too high or the heating time is too long.

[0216] Table 3 Performance of different embodiments

[0217]

[0218] The present invention utilizes the high melting point properties of Mo, W, and Co, designs 3≤Si / (Mo+W+Co)≤8, and designs a Mo:W:Co ratio of 4:2:1; introduces an appropriate amount of Mo / W / Co into the aluminum matrix to increase the solid-liquid phase temperature of the aluminum alloy, and the prepared material has a melting point of 649°C, meeting the high-temperature brazing requirements of the product. At the same time, the high-temperature dispersion strengthening phase formed reduces the performance degradation of the material after brazing to within 3%; compared with the diffusion of a single element, the combined diffusion of multiple components with high melting points reduces the activation energy of element diffusion during brazing, thereby more conducive to the diffusion of elements between the base material and the solder layer, and obtaining a higher quality weld joint. Unlike patent CN117070808B, which requires controlling the content of impurities such as Mg, Si, and Zn to below 0.2%, the present invention maintains a ratio of silicon to high-melting-point elements between 3 and 8. This prevents the addition of silicon from causing a sharp drop in the solidus temperature of the material, thereby preventing brazing failure. Instead, the addition of appropriate amounts of silicon releases heat during solidification, improving the material's casting flow and formability. The addition of Mg and Zn improves the material's strength and cutting performance, mitigating issues such as tool sticking during subsequent machining.

[0219] At the same time, the design of 6≤(Mn+Fe) / Zr≤20 ensures that the product casting is easy to demold while giving the material excellent thermal properties, which is suitable for later product die-casting and coordinated grain refinement.

[0220] Figure 3 (a) Sample state before salt spray test of the present invention; (b) Sample state after salt spray test of the present invention; (c) Sample state after removing corrosion products of the present invention; (d) Sample state before salt spray test of comparative example 1; (e) Sample state after salt spray test of comparative example 1; (f) Sample state after removing corrosion products of comparative example 1, Figure 3 The material of the present invention exhibits excellent corrosion resistance, with a corrosion rate six times higher than that of existing materials. The present invention also investigates a suitable brazing process for this material. By regulating the composition and brazing temperature parameters, the present invention avoids the formation of large amounts of brittle intermetallic compounds during the welding process and prevents element volatilization, which can cause bubbles and affect weld quality. Figure 4 This is the surface state of Example 2 after heating at 600℃ for 30min; when the ratio of Si / (Mo+W+Co) in Example 2 exceeds the limit, the melting point of the material is only 615℃, and blistering and melting will occur during the brazing process, which cannot meet the product application requirements. The use of highly active flux inhibits the erosion of the base material during welding, thereby improving the welding stability of the product.

[0221] The above shows and describes the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are merely preferred examples of the present invention and are not intended to limit the present invention. Various changes and improvements may be made to the present invention without departing from the spirit and scope of the present invention. Such changes and improvements fall within the scope of the present invention. The scope of protection claimed in the present invention is defined by the appended claims and their equivalents.

Claims

1. A brazable aluminum alloy, characterized in that: The material includes the following: Mn: 1.0-2.0wt%, Fe: 0.6-1.0wt%, Mg: 0.25-0.5wt%, Mo+W+Co: 0.1-0.3wt%, Zr: 0.05-0.3wt%, Si: 0.3-1.3wt%, Sr: 0.015-0.025wt%, Zn: 0.5-1.5wt%, Ni≤0.5wt% and Cu≤0.5wt%; the balance is Al and impurities, wherein the total impurity content is not more than 0.15wt%; The mass fraction relationship between Si, Mo, W and Co is: 3≤Si / (Mo+W+Co)≤8; The mass fraction relationship between Mo, W and Co is: Mo:W:Co=4:2:1; The mass fraction relationship between Mn, Fe and Zr is: 6≤(Mn+Fe) / Zr≤20.

2. The preparation and brazing process of a brazable aluminum alloy according to claim 1, characterized in that: The process specifically comprises the following steps: S1. preparing an alloy melt; S2, refining the alloy melt to complete degassing and impurity removal; S3, feeding the alloy melt into the die-casting machine to obtain the product blank after die-casting, cleaning it, and waiting for welding; S4. Pickling the die casting to be welded and the deformed cover plate to remove foreign matter on the surface, and spraying brazing flux to remove the surface oxide layer; S5. Assemble the casting and the profile cover plate by riveting and pressing. The clamping force is 2KN and the pressure holding time is 5-8s. After the assembly is completed, clean the excess brazing flux on the surface. S6. Place the product into a brazing furnace for welding; S7. Heat treat the product.

3. The preparation and brazing process of a brazable aluminum alloy according to claim 2, characterized in that: The step S1 specifically includes the following steps: a1. Weigh the ingredients according to the designed material formula and prepare the raw materials; a2. Preheat the smelting ladle. The preheating temperature is set to 350℃ and the preheating time is 2h. a3. After preheating, control the melting furnace temperature to 780-800℃, add A00 into the melting furnace and melt it. After melting, take TP sample and confirm the material composition; a4. Add silicon, magnesium ingot, aluminum manganese, zinc ingot, aluminum zirconium, aluminum molybdenum, and aluminum strontium intermediate alloy and stir evenly to obtain an alloy melt.

4. The preparation and brazing process of a brazable aluminum alloy according to claim 2, characterized in that: The step S2 specifically includes the following steps: b1. Introduce nitrogen into the alloy melt as a protective gas at a rate of 0.15-6 L / min; b2. Add RJ-01 refining agent, set the refining time to 20-25min, and the amount of solid refining agent added is 0.2%-0.5% of the alloy melt mass; b3. The alloy melt is degassed by rotation in batches.

5. The preparation and brazing process of a brazable aluminum alloy according to claim 2, characterized in that: The step S3 specifically includes the following steps: c1. The alloy melt is fed into the side furnace of the die casting machine and allowed to stand for 20 minutes; c2. Carry out slag removal; c3. After the aluminum liquid temperature reaches the set temperature, die casting is performed to obtain the product blank; c4. The die-cast product is machined, pickled and high-pressure cleaned to obtain the finished product, ready for welding.

6. The process for preparing and brazing a brazable aluminum alloy according to claim 2, wherein: The step S6 specifically includes the following steps: d1. Set the oxygen content in the furnace to less than 100 ppm, and heat the brazing furnace to 300°C at a rate of 10°C / min and keep it at that temperature for 90 minutes; d2. Heat the brazing furnace to 520°C and hold for 75 minutes at a heating rate of 8°C / min. d3. Raise the temperature of the brazing furnace to 600°C and maintain it for 20 min at a heating rate of 5°C / min; d4, heat the brazing furnace to 615℃ and hold for 10 min at a heating rate of 3℃ / min; d5. After the solder melts and forms an intermediate compound with the base material, control the furnace temperature to decrease to 200°C at a rate of 10°C / min and cool it down. Take out the soldered sample.

7. The process for preparing and brazing a brazable aluminum alloy according to claim 2, wherein: The step S7 specifically includes the following steps: e1. Take the product out of the brazing furnace at 200°C and place it in a solution furnace at 180°C. Heat it up to 520°C at a heating rate of 5°C / min for solution treatment. The solution time is 4 hours. e2. Place the product in 50℃ water for cooling for 10-30s; e3. Place the product in an aging furnace for aging treatment. The aging temperature is 160°C, the aging time is 5 hours, and the cooling method is air cooling.

8. The process for preparing and brazing a brazable aluminum alloy according to claim 3, wherein: In step a4, the forming process is high-pressure casting, the aluminum liquid temperature is set to 700-730° C., the mold temperature is set to 200-250° C., the casting pressure is set to 80-120 MPa, and the speed is set to 0.5 m / s.

9. The process for preparing and brazing a brazable aluminum alloy according to claim 4, wherein: In step b3, the ultrasonic treatment parameters are set as ultrasonic power of 150KW, frequency of 15KHz, ultrasonic time of 10min, and standing time of 2min.

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