A high-strength corrosion-resistant aluminum alloy brazing sheet for a power battery water cooling plate and a preparation method thereof

Abstract

The application discloses a high-strength corrosion-resistant aluminum alloy brazing plate for a power battery water cooling plate and a preparation method thereof. The application discloses a high-strength corrosion-resistant aluminum alloy brazing plate for a power battery water cooling plate and a preparation method thereof. In order to solve the problem that the water cooling plate made of the existing 3003 aluminum alloy is limited by strength and corrosion resistance and is difficult to meet the use requirements of users. The high-strength corrosion-resistant aluminum alloy brazing plate is made of a composite plate, the composite plate is rolled and combined from a core material layer and a brazing layer, and the core material layer is composed of Si, Fe, Cu, M, Zn, Ti and Al. The preparation process comprises the following steps: melting and casting, homogenization treatment, ingot treatment, brazing layer preparation, material covering, preheating before rolling, hot rolling, cold rolling, finished product annealing, finishing, and shearing. The high-strength corrosion-resistant aluminum alloy brazing plate provided by the application has high strength, good elongation, and is not easy to crack during forming, and has high strength and excellent corrosion resistance after brazing. The application is applied to the field of power battery water cooling plates.

Description

Technical Field

[0001] This invention relates to a high-strength corrosion-resistant aluminum alloy brazing plate for power battery water-cooling plates and its preparation method. Background Technology

[0002] With the rapid development of the automotive industry, the environmental pollution, depletion of oil reserves, and resource exhaustion caused by traditional gasoline-powered vehicles are becoming increasingly serious. New energy vehicles, through structural changes, can use various clean energy sources for power, exhibiting better environmental performance and helping to alleviate the shortage of traditional energy sources. In 2023, the production capacity of major new energy vehicle manufacturers continued to increase, with production and sales of new energy vehicles reaching 9.587 million and 9.495 million units respectively, representing year-on-year increases of 35.8% and 37.9%, and a market share of 31.6%.

[0003] As a core component of the power system of new energy vehicles, the power battery's safety is significantly affected by temperature changes during use. Excessive temperature can easily lead to thermal runaway, making the establishment of a battery thermal management system crucial. The water-cooled plate, a key component of the battery thermal management system, maintains full contact with the battery cell surface. Utilizing ethylene glycol and water as cooling media, it leverages the high specific heat capacity and excellent thermal conductivity of the mixture to dissipate the heat generated during battery operation, thus maintaining the battery within a suitable temperature range.

[0004] Early water-cooling plates for new energy vehicles were welded from 3003 aluminum alloy sheets. However, as power batteries develop towards longer range and ultra-fast charging, higher requirements are placed on the performance of power battery water-cooling plates, including mechanical properties and corrosion resistance. Water-cooling plates made of ordinary 3003 aluminum alloy are insufficient to meet user needs due to their limited strength. Summary of the Invention

[0005] To address the limitations of existing 3003 aluminum alloy water-cooling plates in terms of strength and corrosion resistance, which make them unsuitable for meeting user needs, this invention provides a high-strength, corrosion-resistant aluminum alloy brazed plate for power battery water-cooling plates and its preparation method.

[0006] This invention discloses a high-strength corrosion-resistant aluminum alloy brazed plate for power battery water cooling plates, which is rolled and composited from a brazed layer and a core material layer. The core material layer aluminum alloy is composed of 0.4% to 1.0% Si, 0.2% to 0.7% Fe, 0.2% to 1.1% Cu, 1.2% to 1.8% Mn, Zn ≤ 0.05%, Ti 0.05% to 0.2%, and the balance Al by mass percentage. The brazed layer is 4045 aluminum alloy.

[0007] A method for preparing a high-strength, corrosion-resistant aluminum alloy brazing plate for a power battery water-cooling plate is carried out according to the following steps:

[0008] I. Weigh out 0.4%–1.0% Si, 0.2%–0.7% Fe, and 0.2%–1.1% Cu by mass percentage.

[0009] The raw material for the core layer is obtained by adding 1.2% to 1.8% Mn, ≤0.05% Zn, 0.05% to 0.2% Ti, and the balance Al; then, semi-continuous casting is carried out to obtain the core layer alloy ingot.

[0010] 2. Heat the core material layer alloy ingot to 600℃~630℃ and hold for 16h~24h to carry out homogenization annealing treatment of the ingot.

[0011] 3. Mill the surfaces of the 4045 alloy ingot with brazing layer and the alloy ingot with core material layer after step 2.

[0012] 4. The preheated brazing layer alloy ingot is hot-rolled and sawn.

[0013] 5. Stack the hot-rolled brazed layer alloy ingot on top of the core layer alloy ingot, and drill holes at the four corners of the brazed layer blank plate and the core layer alloy ingot in a direction perpendicular to the plate surface and rivet them to obtain the composite alloy ingot.

[0014] 6. The composite alloy ingot is preheated and then hot-rolled into a composite hot-rolled coil; the composite hot-rolled coil is rolled again into a composite cold-rolled coil and annealed to obtain an annealed coil.

[0015] 7. The annealed coil is straightened and shaped on a bending straightening machine, and then cut to obtain a high-strength corrosion-resistant aluminum alloy brazed plate for power battery water cooling plate.

[0016] Beneficial effects of this invention:

[0017] The brazed sheet material of this invention has good mechanical properties, is suitable for stamping, and has good corrosion resistance. Performance testing shows that the core material of the high-strength corrosion-resistant aluminum alloy brazed sheet material for power battery water-cooling plates has an average grain size ≤80μm, a yield strength ≥60MPa, a tensile strength ≥160MPa, an elongation ≥24%, a yield strength ≥55MPa after brazing, a tensile strength ≥150MPa, and a corrosion depth of approximately 75μm after immersion for 50 days after brazing. Attached Figure Description

[0018] Figure 1 A process flow diagram for preparing high-strength corrosion-resistant aluminum alloy brazing plates for this application;

[0019] Figure 2Metallographic diagram of the high-strength corrosion-resistant aluminum alloy brazing plate prepared in Example 3 of this application;

[0020] Figure 3 The image shows the metallographic structure of the high-strength corrosion-resistant aluminum alloy sheet prepared in Example 3 of this application after brazing. Detailed Implementation

[0021] Specific Implementation Method 1: In this implementation method, a high-strength corrosion-resistant aluminum alloy brazed plate for a power battery water-cooling plate is formed by rolling a brazing layer and a core material layer. The core material layer aluminum alloy is composed of 0.4% to 1.0% Si, 0.2% to 0.7% Fe, 0.2% to 1.1% Cu, 1.2% to 1.8% Mn, Zn ≤ 0.05%, Ti 0.05% to 0.2%, and the balance Al by mass percentage. The brazing layer is 4045 aluminum alloy.

[0022] Using the proportions of this embodiment, the amount of solder melted can meet the brazing requirements without causing core material erosion due to excessive solder.

[0023] In this embodiment, the core material of the water-cooled plate has a Mn content of 1.2% to 1.8%. A high Mn content strengthens the alloy, increases the recrystallization temperature of the plate, and further reduces the diffusion of other solute atoms, thus improving the alloy's heat resistance and strength. When the Mn content is below 0.5%, the strengthening effect on the alloy is insufficient. However, when the Mn content is above 1.8%, the solid solubility of Mn in the alloy reaches its limit, making it prone to precipitation from the matrix and forming a large amount of brittle Al6Mn compounds, which easily lead to cracking during deformation. In order to improve the strength of the composite plate, this application preferably uses an Mn content of not less than 1.2%.

[0024] In this embodiment, the core material Fe of the water-cooled plate can dissolve in Al6Mn to form Al6(FeMn) compounds. An appropriate amount of Al6(FeMn) phase can prevent the accumulation of aluminum chips in the mold during the stamping process. If the Fe content is higher than 0.7%, a large amount of coarse Al6(FeMn) compounds will be formed, which will significantly reduce the mechanical properties of the alloy. In this application, the Fe content is controlled at 0.2% to 0.7%.

[0025] In this embodiment, the core material Si of the water-cooled plate can form a complex T-phase (Al) with Mn. 12 In addition to Mn3Si2, Si can also promote the decomposition of supersaturated solid solutions, forming high-density dispersed fine particles, thereby improving the alloy strength. When the Si content is higher than 0.9%, the melting point of the core alloy decreases, increasing the risk of core material corrosion during brazing. In this application, the Si content is controlled below 1.0%.

[0026] In this embodiment, the Cu core material of the water-cooled plate can cause lattice distortion in the α-solid solution within the alloy, enriching it in dislocation-dense regions, hindering dislocation slip, and strengthening the alloy. When the Cu content exceeds 0.1%, an Al₂Cu phase can be formed, which also improves the alloy's strength. Cu can also increase the alloy's corrosion potential, enhancing the core material's corrosion resistance. However, the Cu content should not be too high, otherwise it will deteriorate the alloy's resistance to intergranular corrosion and reduce its corrosion resistance. In this application, the Cu content does not exceed 1.0%.

[0027] In this embodiment, adding Ti to the core alloy of the water-cooled plate can refine the as-cast grains, prevent cracking during alloy casting, and improve the corrosion resistance of the alloy to a certain extent. However, when the Ti content is greater than 0.15%, coarse Al3Ti phases can be formed in the ingot, which can easily cause cracks and lead to ingot cracking. In this application, the Ti content is controlled between 0.05% and 0.2%.

[0028] Specific Implementation Method Two: This implementation method describes a method for preparing a high-strength, corrosion-resistant aluminum alloy brazing plate for a power battery water-cooling plate, which is carried out according to the following steps:

[0029] 1. Weigh out 0.4%–1.0% Si, 0.2%–0.7% Fe, 0.2%–1.1% Cu, 1.2%–1.8% Mn, Zn ≤ 0.05%, Ti 0.05%–0.2%, with the balance being Al, according to the mass percentage, to obtain the core material raw material; then perform semi-continuous casting to obtain the core material alloy ingot;

[0030] 2. Heat the core material layer alloy ingot to 600℃~630℃ and hold for 16h~24h to carry out homogenization annealing treatment of the ingot.

[0031] 3. Mill the surfaces of the 4045 alloy ingot with brazing layer and the alloy ingot with core material layer after step 2.

[0032] 4. The preheated brazing layer alloy ingot is hot-rolled and sawn.

[0033] 5. Stack the hot-rolled brazed layer alloy ingot on top of the core layer alloy ingot, and drill holes at the four corners of the brazed layer blank plate and the core layer alloy ingot in a direction perpendicular to the plate surface and rivet them to obtain the composite alloy ingot.

[0034] 6. The composite alloy ingot is preheated and then hot-rolled into a composite hot-rolled coil; the composite hot-rolled coil is rolled again into a composite cold-rolled coil and annealed to obtain an annealed coil.

[0035] 7. The annealed coil is straightened and shaped on a bending straightening machine, and then cut to obtain a high-strength corrosion-resistant aluminum alloy brazed plate for power battery water cooling plate.

[0036] Specific Implementation Method 3: This implementation method differs from Specific Implementation Method 2 in that the thickness of the brazing layer alloy ingot is 5% to 10% of the thickness of the composite alloy ingot. Everything else is the same as in Specific Implementation Method 2.

[0037] Specific Implementation Method Four: This implementation method differs from Specific Implementation Method Two or Three in that step three, milling the surfaces, involves milling the top and bottom surfaces to a depth of 5mm to 15mm, and milling the side facets to a depth of 2mm to 10mm. Everything else is the same as in Specific Implementation Method Two or Three.

[0038] Specific Implementation Method Five: This implementation method differs from Specific Implementation Methods Two to Four in that: in step four, the brazing alloy ingot is placed in a heating furnace and preheated to 480℃~520℃, with a holding time of 2h~6h, to obtain the preheated brazing alloy ingot. Everything else is the same as in Specific Implementation Methods Two to Four.

[0039] Specific Implementation Method Six: This implementation method differs from Specific Implementation Methods Two to Five in that step six involves preheating the composite ingot to 460℃~500℃ and holding it at that temperature for 2h~4h. Everything else is the same as in Specific Implementation Methods Two to Five.

[0040] Specific Implementation Method Seven: This implementation method differs from Specific Implementation Methods Two to Six in that the initial rolling temperature in step six is ​​420℃~480℃, and the final rolling temperature is 300℃~360℃. Everything else is the same as in Specific Implementation Methods Two to Six.

[0041] Specific Implementation Method Eight: This implementation method differs from Specific Implementation Methods Two to Seven in that the thickness of the composite hot-rolled material coil in step six is ​​3.0mm to 5.0mm. Everything else is the same as in Specific Implementation Methods Two to Seven.

[0042] Specific Implementation Method Nine: This implementation method differs from Specific Implementation Methods Two to Eight in that the final rolling pass reduction rate of the composite cold-rolled coil is 20% to 40%, and the finished product thickness is 1.0 mm to 2.0 mm. Everything else is the same as in Specific Implementation Methods Two to Eight.

[0043] Specific Implementation Method Ten: This implementation method differs from Specific Implementation Methods Two to Nine in that the annealing temperature in step six is ​​340℃~440℃, and the holding time is 1h~3h. Everything else is the same as in Specific Implementation Methods Two to Nine.

[0044] The scope of this invention is not limited to the above-described embodiments; a combination of one or more specific embodiments can also achieve the purpose of the invention.

[0045] The present application will be described in detail below with reference to specific embodiments:

[0046] Example 1

[0047] The core material composition by mass percentage is as follows: Si: 0.7%, Fe: 0.5%, Cu: 1.0%, Mn: 1.7%, Zn: 0.05%, Ti: 0.16%, with each impurity element having a single content of <0.05% and a total content of <0.15%, with the balance being Al.

[0048] (1) Melting and casting: Weigh the raw materials according to the above composition, add them to the melting furnace for melting, and after melting, electromagnetic stirring, slag removal, degassing and refining, semi-continuous casting is carried out to obtain the core material layer alloy ingot; the brazing layer alloy ingot is a 4045 alloy ingot with a specification of 440mm×1600mm×4900mm, and the core material layer alloy ingot has a specification of 440mm×1700mm×4900mm.

[0049] (2) Homogenization treatment: After the core alloy is cast, the ingot is heated to 620°C and held for 20 hours to carry out homogenization annealing treatment to reduce and eliminate intragranular segregation.

[0050] (3) Ingot processing: Mill the brazing layer ingot and the core material layer ingot according to the specifications. The milling depth of the top and bottom surfaces is 10mm, and the milling depth of the small surfaces on both sides is 5mm. Cut off the head and tail of the ingot.

[0051] (4) Preparation of brazing layer: The brazing layer alloy ingot is placed in a heating furnace and preheated to 500°C for 3 hours. After being taken out of the furnace, it is hot rolled into a slab with a thickness of 40 mm, and then sawn into 40 mm × 1600 mm × 4000 mm.

[0052] (5) Material bonding: The brazing layer blank plate is stacked on the core material layer alloy ingot, and holes are drilled and riveted at the four corners of the brazing layer blank plate and the core material layer alloy ingot in a direction perpendicular to the plate surface.

[0053] (6) Preheating before rolling: The mechanically composited alloy ingot is preheated to 500°C and held for 2 hours.

[0054] (7) Hot rolling: The preheated composite ingot is hot rolled at an initial rolling temperature of 480°C and a final rolling temperature of 320°C, and rolled into a 4.0 mm composite hot-rolled coil in multiple passes.

[0055] (8) Cold rolling: The composite hot-rolled coil is rolled into a 1.5mm composite cold-rolled coil through 3 passes, with a final rolling rate of 25%.

[0056] (9) Finished product annealing: The composite cold-rolled coil is annealed at 400℃ and held for 2 hours.

[0057] (10) Finishing: The finished annealed coil is straightened and shaped on a bending straightening machine to obtain finished aluminum alloy composite sheet.

[0058] (11) Shearing: The finished aluminum alloy composite plate is sheared to obtain a high-strength corrosion-resistant aluminum alloy finished plate for power battery water cooling plate.

[0059] (12) Simulated brazing: The finished composite plate was placed into the Nabo thermal test furnace for simulated brazing. The simulated brazing temperature was 610℃, and the temperature was held for 5 minutes. The plate was then slowly cooled to 300℃ in the furnace and then air-cooled to room temperature.

[0060] The average grain size of the core material of the composite plate was 66.0 μm. According to GB / T 16865-2023 "Tension Test Specimens and Methods for Processed Articles of Wrought Aluminum, Magnesium and Their Alloys", the longitudinal tensile strength of the high-strength corrosion-resistant aluminum alloy brazed plate for power battery water-cooling plates prepared in this application was 173.3 MPa, the yield strength was 65.0 MPa, and the elongation after fracture was 24.0%. The tensile strength of the brazed composite plate was 168.2 MPa, and the yield strength was 59.6 MPa. An immersion corrosion test was conducted on the brazed composite plate according to GB / T7998-2023 standard. The corrosion depth of the plate after 50 days of immersion was 80 μm.

[0061] Example 2

[0062] The core material composition by weight percentage is as follows: Si: 0.6%, Fe: 0.4%, Cu: 0.6%, Mn: 1.6%, Zn: 0.03%, Ti: 0.15%, with individual impurity elements containing less than 0.05% and total impurity elements containing less than 0.15%, and the balance being Al.

[0063] (1) Melting and casting: Weigh the raw materials according to the above composition, add them to the melting furnace for melting, and after melting, electromagnetic stirring, slag removal, degassing and refining, semi-continuous casting is carried out to obtain the core material layer alloy ingot; the brazing layer alloy ingot is a 4045 alloy ingot with a specification of 440mm×1600mm×4900mm, and the core material layer alloy ingot has a specification of 440mm×1700mm×4900mm.

[0064] (2) Homogenization treatment: After the core alloy is cast, the ingot is heated to 610℃ and held for 20h to carry out homogenization annealing treatment to reduce and eliminate intragranular segregation.

[0065] (3) Ingot processing: Mill the brazing layer ingot and the core material layer ingot according to the specifications. The milling depth of the top and bottom surfaces is 10mm, and the milling depth of the small surfaces on both sides is 5mm. Cut off the head and tail of the ingot.

[0066] (4) Preparation of brazing layer: The brazing layer alloy ingot is placed in a heating furnace and preheated to 510°C for 2 hours. After being taken out of the furnace, it is hot rolled into a slab with a thickness of 40 mm, and then sawn into 40 mm × 1600 mm × 4000 mm.

[0067] (5) Material bonding: The brazing layer blank plate is stacked on the core material layer alloy ingot, and holes are drilled and riveted at the four corners of the brazing layer blank plate and the core material layer alloy ingot in a direction perpendicular to the plate surface.

[0068] (6) Preheating before rolling: The mechanically composited alloy ingot is preheated to 490°C and held for 3 hours.

[0069] (7) Hot rolling: The preheated composite ingot is hot rolled at a starting temperature of 470°C and a final rolling temperature of 320°C, and rolled in multiple passes to form a 4.0 mm composite hot-rolled coil.

[0070] (8) Cold rolling: The composite hot-rolled coil is rolled into a 2.0 mm composite cold-rolled coil through 3 passes, with a final rolling rate of 29%.

[0071] (9) Finished product annealing: The composite cold-rolled coil is annealed at a temperature of 420℃ and held for 1.5h.

[0072] (10) Finishing: The finished annealed coil is straightened and shaped on a bending straightening machine to obtain finished aluminum alloy composite sheet.

[0073] (11) Shearing: The finished aluminum alloy composite plate is sheared to obtain a high-strength corrosion-resistant aluminum alloy brazing plate for power battery water cooling plate.

[0074] (12) Simulated brazing: After sampling the finished composite board, it was placed into the Nabo thermal test furnace for simulated brazing. The simulated brazing temperature was 600℃, and the temperature was held for 6 minutes. The temperature was then slowly cooled to 350℃ in the furnace and then air-cooled to room temperature.

[0075] The average grain size of the core material of the composite plate was 70.5 μm. According to GB / T 16865-2023 "Tension Test Specimens and Methods for Processed Articles of Wrought Aluminum, Magnesium and Their Alloys", the longitudinal tensile strength of the high-strength corrosion-resistant aluminum alloy brazed plate for power battery water-cooling plates prepared in this application was 171.0 MPa, the yield strength was 64.2 MPa, and the elongation after fracture was 25.1%. The tensile strength of the brazed composite plate was 165.5 MPa, and the yield strength was 58.4 MPa. An immersion corrosion test was conducted on the brazed composite plate according to GB / T7998-2023 standard. The corrosion depth of the plate after 50 days of immersion was 75 μm.

[0076] Example 3

[0077] The core material composition by weight percentage is as follows: Si: 0.7%, Fe: 0.5%, Cu: 0.7%, Mn: 1.5%, Zn: 0.05%, Ti: 0.14%, with individual impurity elements containing less than 0.05% and total impurity elements containing less than 0.15%, and the balance being Al.

[0078] (1) Melting and casting: Weigh the raw materials according to the above composition, add them to the melting furnace for melting, and after melting, electromagnetic stirring, slag removal, degassing and refining, semi-continuous casting is carried out to obtain the core material layer alloy ingot; the brazing layer alloy ingot is a 4045 alloy ingot with a specification of 440mm×1600mm×4900mm, and the core material layer alloy ingot has a specification of 440mm×1700mm×4900mm.

[0079] (2) Homogenization treatment: After the core alloy is cast, the ingot is heated to 610℃ and held for 18 hours to carry out homogenization annealing treatment to reduce and eliminate intragranular segregation.

[0080] (3) Ingot processing: Mill the brazing layer ingot and the core material layer ingot according to the specifications. The milling depth of the top and bottom surfaces is 10mm, and the milling depth of the small surfaces on both sides is 5mm. Cut off the head and tail of the ingot.

[0081] (4) Preparation of brazing layer: The brazing layer alloy ingot is placed in a heating furnace and preheated to 500℃ for 2 hours. After being taken out of the furnace, it is hot rolled into a slab with a thickness of 40mm, and then sawn into 40mm×1600mm×4000mm.

[0082] (5) Material bonding: The brazing layer blank plate is stacked on the core material layer alloy ingot, and holes are drilled and riveted at the four corners of the brazing layer blank plate and the core material layer alloy ingot in a direction perpendicular to the plate surface.

[0083] (6) Preheating before rolling: The mechanically composited alloy ingot is preheated to 500°C and held for 2 hours.

[0084] (7) Hot rolling: The preheated composite ingot is hot rolled at an initial rolling temperature of 480°C and a final rolling temperature of 320°C, and rolled into a 4.0 mm composite hot-rolled coil in multiple passes.

[0085] (8) Cold rolling: The composite hot-rolled coil is rolled into a composite cold-rolled coil of 1.0 mm through 3 passes, with a final rolling rate of 33%.

[0086] (9) Finished product annealing: The composite cold-rolled coil is annealed at 400℃ and held for 2 hours.

[0087] (10) Finishing: The finished annealed coil is straightened and shaped on a bending straightening machine to obtain finished aluminum alloy composite sheet.

[0088] (11) Shearing: The finished aluminum alloy composite plate is sheared to obtain a high-strength corrosion-resistant aluminum alloy brazing plate for power battery water cooling plate.

[0089] (12) Simulated brazing: Samples of finished composite boards were placed into the Nabo thermal test furnace for simulated brazing. The simulated brazing temperature was 590℃, and the temperature was held for 8 minutes. The temperature was then slowly cooled to 300℃ in the furnace and then air-cooled to room temperature.

[0090] The average grain size of the core material of the composite plate was 73.0 μm. According to GB / T 16865-2023 "Tension Test Specimens and Methods for Processed Articles of Wrought Aluminum, Magnesium and Their Alloys", the longitudinal tensile strength of the high-strength corrosion-resistant aluminum alloy brazed plate for power battery water-cooling plates prepared in this application was 168.0 MPa, the yield strength was 63.2 MPa, and the elongation after fracture was 24.8%. The tensile strength of the brazed composite plate was 161.3 MPa, and the yield strength was 59.2 MPa. An immersion corrosion test was conducted on the brazed composite plate according to GB / T7998-2023 standard. The corrosion depth of the plate after 50 days of immersion was 72 μm. Figure 1 This is a process flow diagram of the preparation method in the above embodiments.

[0091] Figure 2 The image shown is a metallographic diagram of the composite plate obtained in this embodiment. It can be seen that the brazing layer of the composite plate is uniformly coated with a coating rate of 10%. The core material layer has a recrystallized structure with uniform grain distribution. The long side is distributed along the rolling direction, and the average grain size is 73.0 μm.

[0092] Figure 3 The image shown is a metallographic structure of the composite plate obtained in this embodiment after brazing. It can be seen that the brazed layer of the composite plate recrystallizes and grows after melting. The brazed layer is evenly distributed after welding. The structure of the core material layer is a recrystallized structure. The grains grow after brazing, and the long side is distributed along the rolling direction.

[0093] Example 4

[0094] The core material composition by mass percentage is as follows: Si: 0.5%, Fe: 0.35%, Cu: 0.5%, Mn: 1.5%, Zn: 0.04%, Ti: 0.13%, with each impurity element having a single content of <0.05% and a total content of <0.15%, with the balance being Al.

[0095] (1) Melting and casting: Weigh the raw materials according to the above composition, add them to the melting furnace for melting, and after melting, electromagnetic stirring, slag removal, degassing and refining, semi-continuous casting is carried out to obtain the core material layer alloy ingot; the brazing layer alloy ingot is a 4045 alloy ingot with a specification of 440mm×1600mm×4900mm, and the core material layer alloy ingot has a specification of 440mm×1700mm×4900mm.

[0096] (2) Homogenization treatment: After the core alloy is cast, the ingot is heated to 600℃ and held for 20h to carry out homogenization annealing treatment to reduce and eliminate intragranular segregation.

[0097] (3) Ingot processing: Mill the brazing layer ingot and the core material layer ingot according to the specifications. The milling depth of the top and bottom surfaces is 10mm, and the milling depth of the small surfaces on both sides is 5mm. Cut off the head and tail of the ingot.

[0098] (4) Preparation of brazing layer: The brazing layer alloy ingot is placed in a heating furnace and preheated to 490°C for 3 hours. After being taken out of the furnace, it is hot rolled into a slab with a thickness of 40 mm, and then sawn into 40 mm × 1600 mm × 4000 mm.

[0099] (5) Material bonding: The brazing layer blank plate is stacked on the core material layer alloy ingot, and holes are drilled and riveted at the four corners of the brazing layer blank plate and the core material layer alloy ingot in a direction perpendicular to the plate surface.

[0100] (6) Preheating before rolling: The mechanically composited alloy ingot is preheated to 490°C and held for 2 hours.

[0101] (7) Hot rolling: The preheated composite ingot is hot rolled at an initial rolling temperature of 470°C and a final rolling temperature of 320°C, and rolled in multiple passes to form a 4.2 mm composite hot-rolled coil.

[0102] (8) Cold rolling: The composite hot-rolled coil is rolled into a 1.5mm composite cold-rolled coil through 3 passes, with a final rolling rate of 25%.

[0103] (9) Finished product annealing: The composite cold-rolled coil is annealed at 380℃ for 2 hours.

[0104] (10) Finishing: The finished annealed coil is straightened and shaped on a bending straightening machine to obtain finished aluminum alloy composite sheet.

[0105] (11) Shearing: The finished aluminum alloy composite plate is sheared to obtain a high-strength corrosion-resistant aluminum alloy brazing plate for power battery water cooling plate.

[0106] (12) Simulated brazing: After sampling the finished composite board, it was placed into the Nabo thermal test furnace for simulated brazing. The simulated brazing temperature was 600℃, and the temperature was held for 4 minutes. The temperature was then slowly cooled to 350℃ in the furnace and then air-cooled to room temperature.

[0107] The average grain size of the core material of the composite plate was 75.3 μm. According to GB / T 16865-2023 "Tension Test Specimens and Methods for Processed Products of Wrought Aluminum, Magnesium and Their Alloys", the longitudinal tensile strength of the high-strength corrosion-resistant brazed plate for power battery water-cooling plates prepared in this application was 164.0 MPa, the yield strength was 66.0 MPa, and the elongation after fracture was 26.2%. The tensile strength of the brazed composite plate was 158.7 MPa, and the yield strength was 60.2 MPa. An immersion corrosion test was conducted on the brazed composite plate according to GB / T7998-2023 standard. The corrosion depth of the plate after 50 days of immersion was 70 μm.

[0108] Comparative Example 1

[0109] The core material composition by mass percentage is as follows: Si: 0.6%, Fe: 0.4%, Cu: 0.1%, Mn: 1.4%, Zn: 0.04%, Ti: 0.14%, with each impurity element having a single content of <0.05% and a total content of <0.15%, with the balance being Al.

[0110] (1) Melting and casting: Weigh the raw materials according to the above composition, add them to the melting furnace for melting, and after melting, electromagnetic stirring, slag removal, degassing and refining, semi-continuous casting is carried out to obtain the core material layer alloy ingot; the brazing layer alloy ingot is a 4045 alloy ingot with a specification of 440mm×1600mm×4900mm, and the core material layer alloy ingot has a specification of 440mm×1700mm×4900mm.

[0111] (2) Homogenization treatment: After the core alloy is cast, the ingot is heated to 600℃ and held for 18 hours to carry out homogenization annealing treatment to reduce and eliminate intragranular segregation.

[0112] (3) Ingot processing: Mill the brazing layer ingot and the core material layer ingot according to the specifications. The milling depth of the top and bottom surfaces is 10mm, and the milling depth of the small surfaces on both sides is 5mm. Cut off the head and tail of the ingot.

[0113] (4) Preparation of brazing layer: The brazing layer alloy ingot is placed in a heating furnace and preheated to 500°C for 2 hours. After being taken out of the furnace, it is hot rolled into a slab with a thickness of 40 mm, and then sawn into 40×1600×4000 mm.

[0114] (5) Material bonding: The brazing layer blank plate is stacked on the core material layer alloy ingot, and holes are drilled and riveted at the four corners of the brazing layer blank plate and the core material layer alloy ingot in a direction perpendicular to the plate surface.

[0115] (6) Preheating before rolling: The mechanically composited alloy ingot is preheated to 490°C and held for 2 hours.

[0116] (7) Hot rolling: The preheated composite ingot is hot rolled at an initial rolling temperature of 470°C and a final rolling temperature of 320°C, and rolled into a 4.0 mm composite hot-rolled coil in multiple passes.

[0117] (8) Cold rolling: The composite hot-rolled coil is rolled into a 1.5mm composite cold-rolled coil through 3 passes, with a final rolling rate of 25%.

[0118] (9) Finished product annealing: The composite cold-rolled coil is annealed at 400℃ and held for 2 hours.

[0119] (10) Finishing: The finished annealed coil is straightened and shaped on a bending straightening machine to obtain finished aluminum alloy composite sheet.

[0120] (11) Shearing: The finished aluminum alloy composite plate is sheared to obtain a high-strength corrosion-resistant aluminum alloy finished plate for power battery water cooling plate.

[0121] (12) Simulated brazing: Samples of finished composite boards were placed into the Nabo thermal test furnace for simulated brazing. The simulated brazing temperature was 590℃, and the temperature was held for 6 minutes. The temperature was then slowly cooled to 350℃ in the furnace and then air-cooled to room temperature.

[0122] The average grain size of the core material of the composite plate was 80.1 μm. According to GB / T 16865-2023 "Tension Test Specimens and Methods for Processed Articles of Wrought Aluminum, Magnesium and Their Alloys", the longitudinal tensile strength of the high-strength corrosion-resistant aluminum alloy plate for power battery water-cooling plates prepared in this application was 155.6 MPa, the yield strength was 60.3 MPa, and the elongation after fracture was 22%. After brazing, the tensile strength of the composite plate was 150.4 MPa, and the yield strength was 55.5 MPa. Immersion corrosion tests were conducted on the brazed composite plate according to GB / T7998-2023 standard. The corrosion depth of the plate after 50 days of immersion was 125 μm.

[0123] Comparative Example 2

[0124] The core material composition by mass percentage is as follows: Si: 0.6%, Fe: 0.5%, Cu: 0.15%, Mn: 1.3%, Zn: 0.05%, Ti: 0.15%, with each impurity element having a single content of <0.05% and a total content of <0.15%, with the balance being Al.

[0125] (1) Melting and casting: Weigh the raw materials according to the above composition, add them to the melting furnace for melting, and after melting, electromagnetic stirring, slag removal, degassing and refining, semi-continuous casting is carried out to obtain the core material layer alloy ingot; the brazing layer alloy ingot is a 4045 alloy ingot with a specification of 440mm×1600mm×4900mm, and the core material layer alloy ingot has a specification of 440mm×1700mm×4900mm.

[0126] (2) Homogenization treatment: After the core alloy is cast, the ingot is heated to 610℃ and held for 18 hours to carry out homogenization annealing treatment to reduce and eliminate intragranular segregation.

[0127] (3) Ingot processing: Mill the brazing layer ingot and the core material layer ingot according to the specifications. The milling depth of the top and bottom surfaces is 10mm, and the milling depth of the small surfaces on both sides is 5mm. Cut off the head and tail of the ingot.

[0128] (4) Preparation of brazing layer: The brazing layer alloy ingot is placed in a heating furnace and preheated to 500°C for 2 hours. After being taken out of the furnace, it is hot rolled into a slab with a thickness of 40 mm, and then sawn into 40×1600×4000 mm.

[0129] (5) Material bonding: The brazing layer blank plate is stacked on the core material layer alloy ingot, and holes are drilled and riveted at the four corners of the brazing layer blank plate and the core material layer alloy ingot in a direction perpendicular to the plate surface.

[0130] (6) Preheating before rolling: The mechanically composited ingot is preheated to 500°C and held for 2 hours.

[0131] (7) Hot rolling: The preheated composite ingot is hot rolled at an initial rolling temperature of 480°C and a final rolling temperature of 320°C, and rolled into a 4.0 mm composite hot-rolled coil in multiple passes.

[0132] (8) Cold rolling: The composite hot-rolled coil is rolled into a 2.0 mm composite cold-rolled coil through 3 passes, with a final rolling rate of 29%.

[0133] (9) Finished product annealing: The composite cold-rolled coil is annealed at 380℃ for 2 hours.

[0134] (10) Finishing: The finished annealed coil is straightened and shaped on a bending straightening machine to obtain finished aluminum alloy composite sheet.

[0135] (11) Shearing: The finished aluminum alloy composite plate is sheared to obtain a high-strength corrosion-resistant aluminum alloy finished plate for power battery water cooling plate.

[0136] (12) Simulated brazing: Samples of finished composite boards were placed into the Nabo thermal test furnace for simulated brazing. The simulated brazing temperature was 600℃, and the temperature was held for 4 minutes. The temperature was then slowly cooled to 350℃ in the furnace and then air-cooled to room temperature.

[0137] The average grain size of the core material of the composite plate was 81.2 μm. According to GB / T 16865-2023 "Tension Test Specimens and Methods for Processed Articles of Wrought Aluminum, Magnesium and Their Alloys", the longitudinal tensile strength of the high-strength corrosion-resistant aluminum alloy plate for power battery water-cooling plates prepared in this application was 155.0 MPa, the yield strength was 61.0 MPa, and the elongation after fracture was 22.5%. After brazing, the tensile strength of the composite plate was 149.2 MPa, and the yield strength was 54.8 MPa. Immersion corrosion tests were conducted on the brazed composite plate according to GB / T7998-2023 standard. The corrosion depth of the plate after 50 days of immersion was 120 μm.

Claims

1. A high-strength, corrosion-resistant aluminum alloy brazing plate for a power battery water-cooling plate, characterized in that, The brazed plate is formed by rolling a brazing layer and a core material layer. The core material consists of the following components by mass percentage: the aluminum alloy core material layer is composed of 0.7% Si, 0.5% Fe, 1.0% Cu, 1.7% Mn, 0.05% Zn, 0.16% Ti, and the balance Al; or 0.6% Si, 0.4% Fe, 0.6% Cu, 1.6% Mn, 0.03% Zn, 0.15% Ti, and the balance Al; or 0.7% Si, 0.5% Fe, 0.7% Cu, 1.5% Mn, 0.05% Zn, 0.14% Ti, and the balance Al; or 0.5% Si, 0.35% Fe, 0.5% Cu, 1.5% Mn, 0.04% Zn, 0.13% Ti, and the balance Al. The brazing layer is made of 4045 aluminum alloy; the core material of the high-strength corrosion-resistant aluminum alloy brazed plate used for the power battery water cooling plate has an average grain size of ≤80μm, a yield strength of ≥60MPa, a tensile strength of ≥160MPa, an elongation of ≥24%, a yield strength of ≥55MPa after brazing, a tensile strength of ≥150MPa, and a corrosion depth of 75μm after immersion for 50 days after brazing.

2. The method for preparing a high-strength corrosion-resistant aluminum alloy brazing plate for a power battery water-cooling plate as described in claim 1, characterized in that, This method is performed in the following steps: Weigh the aluminum alloy raw material of the core layer according to the mass percentage of the core material composition to obtain the core layer raw material; then perform semi-continuous casting to obtain the core layer alloy ingot. The core layer alloy ingot is heated to 600℃~630℃ and held for 16h~24h to perform homogenization annealing treatment. Mill the surfaces of the 4045 alloy ingot with brazing layer and the alloy ingot with core material layer after step two. The preheated brazing layer alloy ingot is hot-rolled and sawn. The hot-rolled brazed layer alloy ingot is stacked on top of the core layer alloy ingot, and holes are drilled and riveted at the four corners of the brazed layer blank plate and the core layer alloy ingot in a direction perpendicular to the plate surface to obtain the composite alloy ingot. The composite alloy ingot is preheated and then hot-rolled into a composite hot-rolled coil; the composite hot-rolled coil is then rolled again into a composite cold-rolled coil and annealed to obtain an annealed coil. The annealed coil is straightened and shaped on a bending straightening machine, and then cut to obtain a high-strength corrosion-resistant aluminum alloy brazed plate for power battery water cooling plates.

3. The method for preparing a high-strength corrosion-resistant aluminum alloy brazing plate for a power battery water-cooling plate according to claim 2, characterized in that, The thickness of the brazed alloy ingot is 5% to 10% of the thickness of the composite alloy ingot.

4. The method for preparing a high-strength corrosion-resistant aluminum alloy brazing plate for a power battery water-cooling plate according to claim 2, characterized in that, Step 3 involves milling the surfaces: the top and bottom surfaces are milled to a depth of 5mm to 15mm, and the two side surfaces are milled to a depth of 2mm to 10mm.

5. The method for preparing a high-strength corrosion-resistant aluminum alloy brazing plate for a power battery water-cooling plate according to claim 2, characterized in that, Step 4: Place the brazing alloy ingot in a heating furnace and preheat it to 480℃~520℃. Hold it for 2h~6h to obtain the preheated brazing alloy ingot.

6. The method for preparing a high-strength corrosion-resistant aluminum alloy brazing plate for a power battery water-cooling plate according to claim 2, characterized in that, Step 6: Preheat the composite ingot to 460℃~500℃ and hold for 2h~4h.

7. The method for preparing a high-strength corrosion-resistant aluminum alloy brazing plate for a power battery water-cooling plate according to claim 2, characterized in that, Step six: The initial rolling temperature for hot rolling is 420℃~480℃, and the final rolling temperature is 300℃~360℃.

8. The method for preparing a high-strength corrosion-resistant aluminum alloy brazing plate for a power battery water-cooling plate according to claim 2, characterized in that, Step 6: The thickness of the composite hot-rolled billet is 3.0mm~5.0mm.

9. The method for preparing a high-strength corrosion-resistant aluminum alloy brazing plate for a power battery water-cooling plate according to claim 2, characterized in that, The final rolling pass reduction rate of the composite cold-rolled coil is 20%~40%, and the finished thickness is 1.0mm~2.0mm.

10. The method for preparing a high-strength corrosion-resistant aluminum alloy brazing plate for a power battery water-cooling plate according to claim 2, characterized in that, Step six: Annealing temperature is 340℃~440℃, and the holding time is 1h~3h.

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