High-strength brazing clad aluminum sheet and method of making

Abstract

The application relates to the field of aluminum alloy materials and composite processing technology, in particular to a high-strength brazing composite aluminum plate and a preparation method thereof. The high-strength brazing composite aluminum plate is sequentially provided with a brazing filler layer, a barrier layer and a core layer from the brazing side to the non-brazing side, and has a thickness of 0.30-0.60 mm, and has high strength, corrosion resistance and stability.

Description

Technical Field

[0001] This invention relates to the field of aluminum alloy materials and their composite processing technology, specifically to a high-strength brazed composite aluminum plate and its preparation method. Background Technology

[0002] To improve the overall performance of brazed composite plates, existing technologies have gradually developed into technical routes employing high-strength core layers, barrier layers, or multi-layer composite structures. These include using 6xxx series alloys as reinforced core layers, placing barrier layers between the solder layer and the core layer to suppress element diffusion, and optimizing hot rolling, cold rolling, and annealing processes to balance brazing performance and mechanical properties. Related technologies indicate that multi-layer composites, core layer reinforcement, and full-process process control have become important development directions in this technical field.

[0003] Meanwhile, the industry's requirements for brazed composite aluminum plates are no longer limited to "being able to complete brazing connections." They now demand that the materials maintain high strength, good interfacial bonding, low risk of liquid film migration, and stable corrosion resistance under the combined effects of pre-strain, subsequent brazing thermal cycles, and service environment. Therefore, research on composite layer design, core alloy selection, barrier layer continuity control, and the stability of the entire preparation process has become a key focus for the continued development of this field.

[0004] Existing technologies control element diffusion by setting a blocking layer in the composite aluminum plate, but cannot control element migration caused by thermal cycling during processing, or only improve the mechanical properties of the composite aluminum plate, making it difficult to achieve high strength, corrosion resistance and stability at the same time.

[0005] In summary, there is an urgent need for a composite aluminum plate that combines high strength, corrosion resistance, and stability, as well as a method for its preparation. Summary of the Invention

[0006] The present invention aims to solve the technical problem of how to provide a composite aluminum plate that combines high strength, corrosion resistance and stability.

[0007] To achieve the above objectives, the first aspect of the present invention provides a high-strength brazed composite aluminum plate, wherein the high-strength brazed composite aluminum plate comprises, from the brazed side to the non-brazed side, a brazing filler layer, a barrier layer and a core layer.

[0008] The components and their weight percentages in the solder layer are as follows:

[0009] Si 9.0~11.0%, Fe 0.15~0.45%, Cu≤0.10%, Mn≤0.15%, Mg≤0.03%, Zn≤0.10%, Ti≤0.08%, other individual impurities ≤0.05%, total impurities ≤0.15%, balance Al;

[0010] The components and their weight percentages in the barrier layer are as follows:

[0011] The composition is as follows: Si 0.05~0.20%, Fe 0.10~0.35%, Cu 0.05~0.20%, Mn 1.00~1.35%, Mg≤0.03%, Zn≤0.05%, Cr≤0.05%, Zr 0~0.05%, Ti≤0.05%, with other individual impurities ≤0.05%, total impurities ≤0.15%, and the balance being Al. The weight percentage ratio of Cu to Mn is 0.05~0.15.

[0012] The components and their weight percentages in the core layer are as follows:

[0013] Si 0.70~0.95%, Fe 0.10~0.28%, Cu 0.08~0.22%, Mn 0.08~0.25%, Mg 0.45~0.75%, Cr 0.03~0.08%, Zn≤0.08%, Ti≤0.05%, V≤0.05%, Zr 0~0.05%, other individual impurities ≤0.05%, total impurities ≤0.15%, balance Al;

[0014] The thickness of the high-strength brazed composite aluminum plate is 0.30–0.60 mm.

[0015] The second aspect of the present invention provides a method for preparing the above-mentioned high-strength brazed composite aluminum plate, comprising the following steps: preparing blanks for the brazing filler layer, the barrier layer and the core layer respectively, surface treatment, blank assembly, preheating, hot rolling, first cold rolling, intermediate annealing, second cold rolling, final annealing, finishing, and obtaining the high-strength brazed composite aluminum plate.

[0016] The preparation method of the blank for the solder layer includes the following steps:

[0017] Batching, smelting, refining, casting, sawing and milling, pre-rolling;

[0018] The preparation method of the preform for the barrier layer includes the following steps:

[0019] Batching, smelting, refining, casting, sawing and milling, pre-rolling;

[0020] The method for preparing the core layer preform includes the following steps:

[0021] Batching, smelting, refining, casting, homogenization, sawing and milling;

[0022] The pre-rolling temperature of the brazing filler layer is 400~480℃, and the pre-rolling is to 25~50% of the original thickness;

[0023] The pre-rolling temperature of the barrier layer is 400~480℃, and it is pre-rolled to 25~50% of the original thickness.

[0024] The beneficial effects of this invention are as follows:

[0025] (1) By controlling the Mg content in the 4045 brazing filler layer to a low level and setting a 3003 barrier layer between the brazing filler layer and the core layer, the migration of Mg to the surface layer during the brazing process can be reduced, thereby reducing the risk of surface contamination and poor brazing and making the brazing seam formation more stable.

[0026] (2) The core layer uses 6451 base composition and controls the range of elements such as Si, Mg, and Cu. It retains a certain strengthening ability after brazing thermal cycling. With subsequent artificial aging treatment, a relatively stable strength level can be obtained to meet the load-bearing requirements of liquid cooling plates and shell components.

[0027] (3) By controlling the core layer composition range and the cold rolling-annealing process, the material has a certain forming ability in the delivery state; after undergoing stamping deformation, the brazing treatment is performed, and the performance change is relatively controllable, reducing the brazing performance fluctuation caused by pre-deformation. Detailed Implementation

[0028] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0029] Existing technologies control element diffusion by setting a blocking layer in the composite aluminum plate, but cannot control element migration caused by thermal cycling during processing, or only improve the mechanical properties of the composite aluminum plate, making it difficult to achieve high strength, corrosion resistance and stability at the same time.

[0030] By adjusting the alloy range of each layer of the composite aluminum plate, specifically Mg and Mn, the inventors addressed the technical problems of Mg migration to the brazing side, interfacial liquid film migration, and the difficulty in balancing strength and corrosion resistance during the brazing process caused by adjusting the Mg and Mn alloy composition. By improving the preparation process, they were able to produce a composite aluminum plate that combines high strength, corrosion resistance, and stability.

[0031] The first aspect of this invention provides a high-strength brazed composite aluminum plate, wherein the components and their weight percentages in the brazing filler layer are as follows:

[0032] Si 9.0~11.0%, Fe 0.15~0.45%, Cu≤0.10%, Mn≤0.15%, Mg≤0.03%, Zn≤0.10%, Ti≤0.08%, other individual impurities ≤0.05%, total impurities ≤0.15%, balance Al;

[0033] The components and their weight percentages in the barrier layer are as follows:

[0034] The composition is as follows: Si 0.05~0.20%, Fe 0.10~0.35%, Cu 0.05~0.20%, Mn 1.00~1.35%, Mg≤0.03%, Zn≤0.05%, Cr≤0.05%, Zr 0~0.05%, Ti≤0.05%, with other individual impurities ≤0.05%, total impurities ≤0.15%, and the balance being Al. The weight percentage ratio of Cu to Mn is 0.05~0.15.

[0035] The components and their weight percentages in the core layer are as follows:

[0036] Si 0.70~0.95%, Fe 0.10~0.28%, Cu 0.08~0.22%, Mn 0.08~0.25%, Mg 0.45~0.75%, Cr 0.03~0.08%, Zn≤0.08%, Ti≤0.05%, V≤0.05%, Zr 0~0.05%, other individual impurities ≤0.05%, total impurities ≤0.15%, balance Al;

[0037] The thickness of the high-strength brazed composite aluminum plate is 0.30–0.60 mm.

[0038] In this invention, the Mg content in the brazing filler layer is adjusted to be below 0.03%. Although the reduced Mg content may lead to a decrease in the strengthening ability of the aluminum alloy sheet, the two-stage homogenization of the core layer, pre-rolling composite, and secondary cold rolling annealing processes in the specific preparation method of this invention enable the Mg and Si elements in the core layer to be fully dissolved and form a stable strengthening phase during subsequent thermal cycling. Simultaneously, it reduces the migration of Mg to the brazing side surface, thereby improving the strength, brazing stability, and corrosion resistance of the aluminum alloy sheet. The specific weight percentage ratio of Cu to Mn in the barrier layer enables the barrier layer to possess high interfacial bonding stability, diffusion barrier capability, and corrosion potential control capability, reducing the migration of Mg, Si, Cu, and other elements from the core layer to the brazing filler layer and lowering the risk of liquid film migration.

[0039] According to the present invention, the proportion of the thickness of each layer in the high-strength brazed composite aluminum plate to the total thickness is as follows: the brazing filler layer is 6~10%, the barrier layer is 5~9%, and the core layer is 81~89%, and the sum of the thickness proportions of the three layers is 100%.

[0040] The grain size of the high-strength brazed composite aluminum plate is 30~120 μm.

[0041] The second aspect of the present invention provides a method for preparing the above-mentioned high-strength brazed composite aluminum plate, characterized in that it includes the following steps: preparing blanks for the brazing filler layer, the barrier layer and the core layer respectively, surface treatment, blank assembly, preheating, hot rolling, first cold rolling, intermediate annealing, second cold rolling, final annealing, finishing, and obtaining the high-strength brazed composite aluminum plate.

[0042] The preparation method of the blank for the solder layer includes the following steps:

[0043] Batching, smelting, refining, casting, sawing and milling, pre-rolling;

[0044] The preparation method of the preform for the barrier layer includes the following steps:

[0045] Batching, smelting, refining, casting, sawing and milling, pre-rolling;

[0046] The method for preparing the core layer preform includes the following steps:

[0047] Batching, smelting, refining, casting, homogenization, sawing and milling;

[0048] The pre-rolling temperature of the brazing filler layer is 400~480℃, and the pre-rolling is to 25~50% of the original thickness;

[0049] The pre-rolling temperature of the barrier layer is 400~480℃, and it is pre-rolled to 25~50% of the original thickness.

[0050] According to the present invention, in the ingredients,

[0051] The recycled material ratio of the solder layer is ≤15%;

[0052] The recycled material ratio of the barrier layer is ≤25%;

[0053] The recycled material ratio of the core layer is ≤20%.

[0054] According to the present invention, the melting conditions include: the melting temperature of the brazing filler layer is 735~755℃, and the melting time is 5~8 h;

[0055] The melting temperature of the barrier layer is 730~750℃, and the melting time is 5~8 h;

[0056] The melting temperature of the core layer is 740~760℃, and the melting time is 5~8 h;

[0057] The refining conditions include: the refining temperature of the solder layer, barrier layer, and core layer is 730~745℃, and the refining time is 15~25 min.

[0058] In this invention, Ar gas is used for online degassing, and the control conditions are: dosage of 2~4 m³ / h. 3 / t, rotor speed is 350~500 rpm; melt temperature of brazing filler layer is 705~725℃, melt temperature of barrier layer and core layer is 715~740℃; hydrogen content is controlled below 0.15 ml / 100g Al, filtration uses 30PPI filter plate, which can increase double-stage filtration.

[0059] According to the present invention, the casting conditions include: casting is used, the casting temperature of the brazing filler layer is 685~705℃, and the casting rate is 20~50 mm / min;

[0060] The casting temperature of the barrier layer is 730~745℃, and the casting rate is 40~55 mm / min;

[0061] The casting temperature of the core layer is 730~745℃, and the casting rate is 35~55 mm / min;

[0062] The milling amount of the sawing milled surface is 1.5~3.0 mm.

[0063] According to the present invention, the conditions for homogenization treatment of the core layer include: first holding at 500~520℃ for 3~5 h, then raising the temperature to 550~565℃ and holding at 550~565℃ for 6~10 h, then cooling in the furnace to below 480℃ and then air-cooling to 20~30℃ after being removed from the furnace.

[0064] According to the present invention, the surface treatment conditions include: alkali washing of the contact surfaces of the solder layer preform and the barrier layer preform, and the contact surfaces of the barrier layer preform and the core layer preform, using a 0.5–1.25 mol / L NaOH aqueous solution at 50–60°C for 30–60 s; washing with a 20–30% HNO3 solution at 20–30°C for 10–20 s; and brushing until the surface roughness Ra is 0.4–0.8 μm.

[0065] According to the present invention, the order of the preform assembly is as follows, from the brazing side to the non-brazing side: solder layer, barrier layer and core layer.

[0066] The preheating conditions include: heating to 460~500℃ and holding at that temperature for 2~4 hours;

[0067] The hot rolling conditions include: an initial rolling temperature of 430~480℃, a total hot rolling reduction rate of 75~90%, a final rolling temperature of 280~340℃, and a hot rolling thickness of 3.0~5.0 mm.

[0068] According to the present invention, the conditions for the primary cold rolling include: a reduction rate of 45-65% in the primary cold rolling;

[0069] The intermediate annealing conditions include: two intermediate annealings, using box annealing with a regime of 280~320℃×2~4 h, or continuous annealing with a regime of 320~380℃×10~30 s.

[0070] In this invention, the effect of two intermediate annealing processes is that they can release the work hardening and residual stress generated by the first cold rolling in stages, restore the material's plasticity, stabilize the interface bonding state between the solder layer, barrier layer and core layer, and inhibit abnormal grain growth during the subsequent final annealing process.

[0071] According to the present invention, the processing rate of the secondary cold rolling is 25-40%;

[0072] The conditions for final annealing include: using box annealing with a temperature of 345~365℃ for 1.5~3h, or using continuous annealing with a temperature of 350~390℃ for 15~35s.

[0073] The finishing conditions include: a flattening elongation of 0.3-0.8%, a tensile elongation of 0.5-1.2%, and a residual oil content ≤25 mg / m² after cleaning. 2 .

[0074] In this invention, all other process parameters not specifically mentioned are standard values ​​in the industry and have no special requirements.

[0075] Test methods

[0076] Chemical composition was determined according to GB / T 7999-2015.

[0077] The thickness of the finished product and the layer thickness shall be determined in accordance with GB / T 33369-2016; GB / T 3880.1-2023; GB / T 3880.3-2024.

[0078] Tensile properties at room temperature were determined in accordance with GB / T 228.1-2021 and GB / T 3880.2-2024.

[0079] Microstructure, grains and interlayer interfaces were determined according to GB / T 3246.1-2024; GB / T 3246.2-2012; GB / T6394-2017.

[0080] The bonding efficiency, barrier layer continuity and liquid film migration were determined according to GB / T 3246.1-2024.

[0081] Corrosion performance was determined according to GB / T 10125-2021.

[0082] The surface Mg enrichment was tested using glow discharge emission spectroscopy (GDOES), with a target of <0.05 wt.%.

[0083] The technical solution of the present invention will be further described in detail below with reference to the embodiments. Obviously, the embodiments described herein are only some embodiments of the present invention and are not intended to limit the present invention. All other embodiments implemented by those skilled in the art based on the embodiments of the present invention without creative improvements are within the protection scope of the present invention.

[0084] Example 1

[0085] The components and their weight percentages in the solder layer are as follows:

[0086] Si 10.0%, Fe 0.30%, Cu 0.05%, Mn 0.08%, Mg 0.02%, Zn 0.05%, Ti 0.04%, with other individual impurities ≤0.05%, total impurities ≤0.15%, and the balance being Al;

[0087] The components and their weight percentages in the barrier layer are as follows:

[0088] The composition is as follows: Si 0.12%, Fe 0.20%, Cu 0.12%, Mn 1.20%, Mg 0.02%, Zn 0.03%, Cr 0.03%, Zr 0.03%, Ti 0.03%, with other individual impurities ≤0.05% and the total amount of impurities ≤0.15%, with the balance being Al. The weight percentage ratio of Cu to Mn is 0.10.

[0089] The components and their weight percentages in the core layer are as follows:

[0090] The composition is as follows: Si 0.82%, Fe 0.18%, Cu 0.15%, Mn 0.15%, Mg 0.60%, Cr 0.05%, Zn 0.04%, Ti 0.03%, V 0.03%, Zr 0.03%, with other individual impurities ≤0.05%, total impurities ≤0.15%, and the balance being Al.

[0091] No recycled materials were found in the solder layer, barrier layer, and core layer.

[0092] The melting temperature of the brazing filler metal layer is 745℃, and the melting time is 6.5 h;

[0093] The melting temperature of the barrier layer is 740℃, and the melting time is 6.5 h;

[0094] The core layer was melted at 750℃ for 6.5 hours.

[0095] The refining temperature of the brazing filler layer, barrier layer, and core layer is 738℃, and the refining time is 20 min.

[0096] The process is by casting, with the solder layer being cast at a temperature of 695℃ and a casting rate of 35 mm / min.

[0097] The casting temperature of the barrier layer is 738℃, and the casting rate is 48 mm / min;

[0098] The core layer was cast at a temperature of 738℃ and a casting rate of 45 mm / min.

[0099] The milling margin for the sawing milled surface is 2.0 mm;

[0100] The pre-rolling temperature of the brazing filler layer is 450℃, and it is pre-rolled to 35% of its original thickness.

[0101] The barrier layer is pre-rolled at 450℃ to 35% of its original thickness.

[0102] Core homogenization: 510℃×4 h+560℃×8 hh;

[0103] The contact surfaces of the solder layer preform and the barrier layer preform, and the contact surfaces of the barrier layer preform and the core layer preform, were alkaline washed with 1.2 mol / L NaOH solution at 55℃ for 45 s, then washed with 25% HNO3 solution at 25℃ for 15 s, and brushed until the surface roughness Ra was 0.6 μm.

[0104] Preheating of billets: 480℃ × 3 h;

[0105] Hot rolling: initial rolling temperature 460℃, total hot rolling reduction 85%, final rolling temperature 320℃, hot rolling to thickness 4.0 mm;

[0106] The reduction rate of a single cold rolling operation is 55%.

[0107] First intermediate annealing: box annealing at 300℃ for 3 hours;

[0108] Second intermediate annealing: box annealing at 300℃ for 2 hours;

[0109] Secondary cold rolling processing rate: 31%;

[0110] Final annealing: 355℃ × 2 h;

[0111] The elongation at flattening is 0.5%, the elongation at tension leveling is 0.8%, and the residual oil content after cleaning is ≤25 mg / m². 2 ;

[0112] A high-strength brazed composite aluminum plate A1 was obtained.

[0113] Finished product thickness: 0.40 mm;

[0114] Layer ratio: 8% / 6% / 86%;

[0115] The grain size of the brazed composite aluminum plate is 60 μm.

[0116] Example 2

[0117] The components and their weight percentages in the solder layer are as follows:

[0118] The composition is as follows: Si 9.0%, Fe 0.15%, Cu 0.03%, Mn 0.05%, Mg 0.01%, Zn 0.03%, Ti 0.03%, with individual impurities ≤0.05% and total impurities ≤0.15%, with the balance being Al.

[0119] The components and their weight percentages in the barrier layer are as follows:

[0120] The composition is as follows: Si 0.05%, Fe 0.10%, Cu 0.05%, Mn 1.00%, Mg 0.01%, Zn 0.02%, Cr 0.02%, Zr 0%, Ti 0.02%, with each individual impurity ≤0.05%, and the total amount of impurities ≤0.15%. The balance is Al, and the weight percentage ratio of Cu to Mn is 0.05.

[0121] The components and their weight percentages in the core layer are as follows:

[0122] The composition is as follows: Si 0.70%, Fe 0.10%, Cu 0.08%, Mn 0.08%, Mg 0.45%, Cr 0.03%, Zn 0.02%, Ti 0.02%, V 0.02%, Zr 0%, with each individual impurity ≤0.05%, the total amount of impurities ≤0.15%, and the balance being Al.

[0123] The recycled material ratio for the solder layer is ≤15%; the recycled material ratio for the barrier layer is ≤25%; and the recycled material ratio for the core layer is ≤20%.

[0124] The melting temperature of the brazing filler layer is 735℃, and the melting time is 5 hours.

[0125] The melting temperature of the barrier layer is 730℃, and the melting time is 5 hours.

[0126] The core layer was melted at 740℃ for 5 hours.

[0127] The refining temperature of the brazing filler layer, barrier layer, and core layer is 730℃, and the refining time is 15 min.

[0128] The process is by casting, with the solder layer being cast at a temperature of 685℃ and a casting rate of 20 mm / min.

[0129] The casting temperature of the barrier layer is 730℃, and the casting rate is 40 mm / min;

[0130] The core layer was cast at a temperature of 730℃ and a casting rate of 35 mm / min.

[0131] The milling margin for the sawing milled surface is 1.5 mm;

[0132] The pre-rolling temperature of the brazing filler layer is 400℃, and it is pre-rolled to 25% of the original thickness.

[0133] The barrier layer is pre-rolled at 400℃ to 25% of its original thickness.

[0134] Core homogenization: 500℃×3 h+550℃×6 h;

[0135] The contact surfaces of the solder layer preform and the barrier layer preform, and the contact surfaces of the barrier layer preform and the core layer preform, were alkaline washed with 0.8 mol / L NaOH solution at 50℃ for 30 s, then washed with 20% HNO3 solution at 20℃ for 10 s, and brushed until the surface roughness Ra was 0.4 μm.

[0136] Preheating of billets: 460℃ × 2 h;

[0137] Hot rolling: initial rolling temperature 430℃, total hot rolling reduction 75%, final rolling temperature 280℃, hot rolling to thickness 3.0 mm;

[0138] The reduction rate of a single cold rolling operation is 45%.

[0139] First intermediate annealing: box annealing at 280℃ for 2 hours;

[0140] Second intermediate annealing: box annealing at 280℃ for 2 hours;

[0141] Secondary cold rolling processing rate: 25%;

[0142] Final annealing: Box annealing at 345℃ for 1.5 h;

[0143] The elongation at flattening is 0.3%, the elongation at tensile straightening is 0.5%, and the residual oil content after cleaning is ≤25 mg / m². 2 ;

[0144] A high-strength brazed composite aluminum plate A2 was obtained.

[0145] Finished product thickness: 0.30 mm;

[0146] Layer ratio: 6% / 5% / 89%;

[0147] The grain size of the brazed composite aluminum plate is 30 μm.

[0148] Example 3

[0149] The components and their weight percentages in the solder layer are as follows:

[0150] The composition is as follows: Si 11.0%, Fe 0.45%, Cu 0.10%, Mn 0.15%, Mg 0.029%, Zn 0.10%, Ti 0.08%, with individual impurities ≤0.05% and total impurities ≤0.15%, with the balance being Al.

[0151] The components and their weight percentages in the barrier layer are as follows:

[0152] The composition is as follows: Si 0.20%, Fe 0.35%, Cu 0.20%, Mn 1.35%, Mg 0.03%, Zn 0.05%, Cr 0.05%, Zr 0.05%, Ti 0.05%, with each individual impurity ≤0.05%, and the total amount of impurities ≤0.15%. The balance is Al, and the weight percentage ratio of Cu to Mn is 0.148.

[0153] The components and their weight percentages in the core layer are as follows:

[0154] The composition is as follows: Si 0.95%, Fe 0.28%, Cu 0.22%, Mn 0.25%, Mg 0.75%, Cr 0.08%, Zn 0.08%, Ti 0.05%, V 0.05%, Zr 0.05%, with each individual impurity ≤0.05%, and the total amount of impurities ≤0.15%, with the balance being Al.

[0155] The recycled material ratio for the solder layer is ≤15%; the recycled material ratio for the barrier layer is ≤25%; and the recycled material ratio for the core layer is ≤20%.

[0156] The melting temperature of the brazing filler layer is 755℃, and the melting time is 8 hours.

[0157] The melting temperature of the barrier layer is 750℃, and the melting time is 8 hours.

[0158] The core layer was melted at 760℃ for 8 hours.

[0159] The refining temperature for the solder layer, barrier layer, and core layer is 745℃, and the refining time is 25 min.

[0160] The process is by casting, with the solder layer being cast at a temperature of 705℃ and a casting rate of 50 mm / min.

[0161] The casting temperature of the barrier layer is 745℃, and the casting rate is 55 mm / min;

[0162] The core layer was cast at a temperature of 745℃ and a casting rate of 55 mm / min.

[0163] The milling margin for the sawing milled surface is 3.0 mm;

[0164] The pre-rolling temperature of the brazing filler layer is 480℃, and it is pre-rolled to 50% of its original thickness;

[0165] The barrier layer is pre-rolled at 480℃ to 50% of its original thickness.

[0166] Core homogenization: 520℃×5 h+565℃×10 h;

[0167] The contact surfaces of the solder layer preform and the barrier layer preform, and the contact surfaces of the barrier layer preform and the core layer preform, were alkaline washed at 60°C for 60 s, then washed with 30% HNO3 solution for 20 s, and brushed until the surface roughness Ra was 0.8 μm.

[0168] Preheating of billets: 500℃ × 4 h;

[0169] Hot rolling: initial rolling temperature 480℃, total hot rolling reduction rate 90%, final rolling temperature 340℃, hot rolling to thickness 5.0 mm;

[0170] The reduction rate of a single cold rolling operation is 65%.

[0171] First intermediate annealing: box annealing at 320℃ for 4 hours;

[0172] Second intermediate annealing: box annealing at 320℃ for 4 hours;

[0173] Final annealing: Box annealing at 365℃ for 3 hours;

[0174] Secondary cold rolling processing rate: 40%;

[0175] The elongation at flattening is 0.8%, the elongation at tension leveling is 1.2%, and the residual oil content after cleaning is ≤25 mg / m². 2 ;

[0176] A high-strength brazed composite aluminum plate A3 was obtained.

[0177] Finished product thickness: 0.60 mm;

[0178] Layer ratio: 10% / 9% / 81%;

[0179] The grain size of the brazed composite aluminum plate is 120 μm.

[0180] Comparative Example 1

[0181] The preparation method is the same as in Example 1, except that the preheating of the preform is 445℃ × 3 h.

[0182] A brazed composite aluminum plate DA1 was obtained.

[0183] Comparative Example 2

[0184] The preparation method is the same as in Example 1, except that the preheating of the preform is 510℃ × 3 h.

[0185] A brazed composite aluminum plate DA2 was obtained.

[0186] Comparative Example 3

[0187] The preparation method is the same as in Example 1, except that the secondary cold rolling processing rate is 20%.

[0188] A brazed composite aluminum plate DA3 was obtained.

[0189] Comparative Example 4

[0190] The preparation method is the same as in Example 1, except that the secondary cold rolling processing rate is 45%.

[0191] A brazed composite aluminum plate DA4 was obtained.

[0192] Comparative Example 5

[0193] The preparation method was the same as in Example 1, except that the final annealing was box annealing: 335℃×2 h;

[0194] A brazed composite aluminum plate DA5 was obtained.

[0195] Comparative Example 6

[0196] The preparation method was the same as in Example 1, except that the final annealing was box annealing: 385℃×4 h;

[0197] DA6 brazed composite aluminum plate was obtained.

[0198] Comparative Example 7

[0199] The preparation method is the same as in Example 1, except that the core layer homogenization process is 500℃×2 h.

[0200] DA7 brazed composite aluminum plate was obtained.

[0201] Comparative Example 8

[0202] The preparation method is the same as in Example 1, except that the core layer homogenization process is 575℃ × 10.

[0203] A brazed composite aluminum plate DA8 was obtained.

[0204] Performance tests were performed on A1-A2 and DA1-DA8, as shown in Table 1.

[0205] Table 1

[0206]

[0207] By comparing the examples and the comparative examples, it can be seen that the high-strength brazed composite aluminum plates of Examples A1-A3 have high strength, corrosion resistance and stability.

[0208] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A high-strength brazed composite aluminum plate, characterized in that, The high-strength brazed composite aluminum plate consists of a brazing layer, a barrier layer, and a core layer, arranged sequentially from the brazed side to the non-brazed side. The components and their weight percentages in the solder layer are as follows: Si 9.0~11.0%, Fe 0.15~0.45%, Cu≤0.10%, Mn≤0.15%, Mg≤0.03%, Zn≤0.10%, Ti≤0.08%, other individual impurities ≤0.05%, total impurities ≤0.15%, balance Al; The components and their weight percentages in the barrier layer are as follows: The composition is as follows: Si 0.05~0.20%, Fe 0.10~0.35%, Cu 0.05~0.20%, Mn 1.00~1.35%, Mg≤0.03%, Zn≤0.05%, Cr≤0.05%, Zr 0~0.05%, Ti≤0.05%, with other individual impurities ≤0.05%, total impurities ≤0.15%, and the balance being Al. The weight percentage ratio of Cu to Mn is 0.05~0.

15. The components and their weight percentages in the core layer are as follows: Si 0.70~0.95%, Fe 0.10~0.28%, Cu 0.08~0.22%, Mn 0.08~0.25%, Mg 0.45~0.75%, Cr 0.03~0.08%, Zn≤0.08%, Ti≤0.05%, V≤0.05%, Zr 0~0.05%, other individual impurities ≤0.05%, total impurities ≤0.15%, balance Al; The thickness of the high-strength brazed composite aluminum plate is 0.30–0.60 mm.

2. The high-strength brazed composite aluminum plate according to claim 1, characterized in that, The proportions of the thickness of each layer in the high-strength brazed composite aluminum plate to the total thickness are as follows: brazing filler layer 6~10%, barrier layer 5~9%, core layer 81~89%; The average grain size of the core layer and barrier layer after final annealing is 30~120 μm.

3. The method for preparing the high-strength brazed composite aluminum plate according to claim 1 or 2, characterized in that, The process includes the following steps: preparing blanks for the brazing filler layer, barrier layer, and core layer respectively; surface treatment; assembly; preheating; hot rolling; first cold rolling; intermediate annealing; second cold rolling; final annealing; finishing, to obtain the high-strength brazed composite aluminum plate. The preparation method of the blank for the solder layer includes the following steps: Batching, smelting, refining, casting, sawing and milling, pre-rolling; The preparation method of the preform for the barrier layer includes the following steps: Batching, smelting, refining, casting, sawing and milling, pre-rolling; The method for preparing the core layer preform includes the following steps: Batching, smelting, refining, casting, homogenization, sawing and milling; The pre-rolling temperature of the brazing filler layer is 400~480℃, and the pre-rolling is to 25~50% of the original thickness; The pre-rolling temperature of the barrier layer is 400~480℃, and it is pre-rolled to 25~50% of the original thickness.

4. The method for preparing the high-strength brazed composite aluminum plate according to claim 3, characterized in that, In the ingredients The recycled material ratio of the solder layer is ≤15%; The recycled material ratio of the barrier layer is ≤25%; The recycled material ratio of the core layer is ≤20%.

5. The method for preparing the high-strength brazed composite aluminum plate according to claim 3, characterized in that, The melting conditions include: the melting temperature of the brazing filler layer is 735~755℃, and the melting time is 5~8 h; The melting temperature of the barrier layer is 730~750℃, and the melting time is 5~8 h; The melting temperature of the core layer is 740~760℃, and the melting time is 5~8 h; The refining conditions include: the refining temperature of the solder layer, barrier layer, and core layer is 730~745℃, and the refining time is 15~25 min.

6. The method for preparing the high-strength brazed composite aluminum plate according to claim 3, characterized in that, The casting conditions include: casting is used, the casting temperature of the brazing filler layer is 685~705℃, and the casting rate is 20~50 mm / min; The casting temperature of the barrier layer is 730~745℃, and the casting rate is 40~55 mm / min; The casting temperature of the core layer is 730~745℃, and the casting rate is 35~55 mm / min; The milling amount of the sawing milled surface is 1.5~3.0 mm.

7. The method for preparing the high-strength brazed composite aluminum plate according to claim 3, characterized in that, The conditions for homogenizing the core layer include: first, holding it at 500~520℃ for 3~5 h, then raising the temperature to 550~565℃ and holding it at 550~565℃ for 6~10 h, then cooling it in the furnace to below 480℃ and air-cooling it to 20~30℃.

8. The method for preparing the high-strength brazed composite aluminum plate according to claim 3, characterized in that, The surface treatment conditions include: alkali washing of the contact surfaces of the solder layer preform and the barrier layer preform, and the contact surfaces of the barrier layer preform and the core layer preform, using a 0.5–1.25 mol / L NaOH aqueous solution at 50–60°C for 30–60 s; followed by washing with a 20–30% HNO3 solution at 20–30°C for 10–20 s; and then brushing until the surface roughness Ra is 0.4–0.8 μm.

9. The method for preparing the high-strength brazed composite aluminum plate according to claim 3, characterized in that, The order of the preform assembly is from the brazing side to the non-brazing side: solder layer, barrier layer, and core layer. The preheating conditions include: heating to 460~500℃ and holding at that temperature for 2~4 hours; The hot rolling conditions include: an initial rolling temperature of 430~480℃, a total hot rolling reduction rate of 75~90%, a final rolling temperature of 280~340℃, and a hot rolling thickness of 3.0~5.0 mm.

10. The method for preparing the high-strength brazed composite aluminum plate according to claim 3, characterized in that, The conditions for the first cold rolling include: a reduction rate of 45-65% in the first cold rolling; The intermediate annealing conditions include: two intermediate annealings, using box annealing with a box annealing regime of 280~320℃×2~4 h, or using continuous annealing with a continuous annealing regime of 320~380℃×10~30 s; The processing rate of the secondary cold rolling is 25-40%; The conditions for final annealing include: using box annealing with a temperature of 345~365℃ for 1.5~3 h, or using continuous annealing with a temperature of 350~390℃ for 15~35 s. The finishing conditions include: a flattening elongation of 0.3-0.8%, a tensile elongation of 0.5-1.2%, and a residual oil content ≤25 mg / m² after cleaning. 2 .

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