A high-strength composite sheet for a new energy vehicle battery liquid cooling plate and a preparation method thereof

Abstract

The application discloses a high-strength composite sheet for a battery liquid cooling plate of a new energy vehicle and a preparation method thereof. The high-strength composite sheet comprises a core material layer and a skin material layer. The core material layer is prepared by melting, refining, casting, sawing, homogenizing heat treatment, face milling, grinding and polishing, brushing and blowing. The skin material layer is prepared by melting, refining, casting, sawing, face milling, preheating, hot rolling, pre-stretching, stabilization treatment, precise sawing, grinding and polishing, brushing and blowing. Then, the obtained core material layer and the skin material layer are welded, preheated, composite hot-rolled, cold-rolled, cleaned, O-state annealed, longitudinally cut, transversely cut and packaged to prepare the high-strength composite sheet. The prepared product has excellent mechanical properties, and can fully meet the technical requirements of the market development of the high-strength composite sheet.

Description

Technical Field

[0001] This invention relates to the field of aluminum alloy composite plate manufacturing technology, and in particular to a high-strength composite plate for liquid cooling plates of new energy vehicle batteries and its preparation method. Background Technology

[0002] my country's main economic indicators for the automotive industry continue to improve, and the industry's development environment continues to improve. Currently, one cooling method for new energy vehicle batteries is indirect cooling. During operation, the coolant flowing through the liquid cooling plate channels uses convection heat transfer and refrigeration to reduce the overall operating temperature of the battery pack, playing a crucial role in real-time rapid cooling.

[0003] Traditional liquid cooling plates for new energy vehicle batteries use conventional 3003 alloy as the core material of the composite plate. Due to the insufficient strength of traditional composite plates, the entire battery pack requires an additional support frame to support its weight. However, with the development of the new energy vehicle industry, higher requirements are being placed on the lightweighting of the overall battery pack, including eliminating the support frame and allowing the liquid cooling plate to provide indirect support. But as the weight of the battery pack increases, the indirect support provided by the liquid cooling plate becomes insufficient, so traditional composite plates are no longer adequate to meet market demands.

[0004] To meet the development and market demand of the lightweighting industry for new energy vehicles, composite plates are needed to replace traditional 3003 alloy as the core material. This invention optimizes and controls the microstructure of the composite plate by studying core material homogenization technology, skin material flatness control technology, and hot rolling composite rolling technology, and finally obtains a high-strength composite plate for liquid cooling plates of new energy vehicle batteries with a stable coverage rate. Summary of the Invention

[0005] The technical problem to be solved by this invention is: based on the application development trend in this field, this invention provides a high-strength composite material for liquid cooling plates of new energy vehicle batteries and its preparation method. The high-strength composite material for liquid cooling plates of new energy vehicle batteries prepared using the technical solution of this invention exhibits excellent mechanical properties; that is, in this application field, the product prepared by this invention can fully meet the technical requirements of the market for high-strength composite materials.

[0006] To solve the above problems, the technical solution adopted by the present invention is as follows:

[0007] This invention provides a high-strength composite material for liquid cooling plates of new energy vehicle batteries, the high-strength composite material comprising a core layer and a skin layer;

[0008] The alloy element composition of the core material layer, expressed as a percentage by mass, is as follows: Si 0.6–1.2%, Fe 0–0.5%, Cu 0.7–1.1%, Mn 1.2–1.8%, Mg 0–0.03%, Cr 0–0.05%, Zn 0–0.1%, Ti 0.02–0.035%, with the balance being Al and unavoidable impurities;

[0009] The alloy element composition of the skin layer, expressed as a percentage by mass, is as follows: Si 9-11%, Fe 0-0.25%, Cu 0-0.3%, Mn 0-0.05%, Mg 0-0.03%, Cr 0-0.05%, Zn 0-0.1%, Ti 0.02-0.03%, with the balance being Al and unavoidable impurities.

[0010] In addition, a method for preparing a high-strength composite material for a liquid cooling plate of a new energy vehicle battery is provided, the method comprising the following steps:

[0011] (a) Preparation of the core layer:

[0012] a. Smelting: Aluminum ingots with a purity >99.70% and process waste are added to a smelting furnace for heating and smelting. The smelting temperature in the furnace is controlled at 720-760℃. After all the raw materials in the furnace have melted, the slag is removed by stirring to obtain the original alloy liquid. Then, at least one of Al-20Mn, Al-20Si, Al-40Cu and titanium additive Ti75 is added for batching at a temperature of 725-740℃. The alloy liquid obtained after batching meets the alloy element composition requirements of the core layer in the above-mentioned high-strength composite plate.

[0013] b. Refining: The core material layer alloy liquid obtained in step a is refined. During the refining process, the temperature is controlled at 720-730℃ and the refining time is 40-120min. After the refining is completed, the slag is removed and the mixture is allowed to stand for 20-40min.

[0014] c. Casting: The aluminum alloy liquid core material obtained after refining in step b is subjected to online primary plate filtration, secondary plate filtration, online degassing and tubular filtration in sequence. The alloy liquid obtained after filtration is cast into aluminum alloy flat ingots.

[0015] d. Sawing: Sawing the aluminum alloy flat ingot with core material layer obtained in step c, sawing the ingot head 300-500mm, and leaving the ingot tail unsaved;

[0016] e. Homogenization heat treatment: The sawn core aluminum alloy flat ingots obtained in step d are subjected to homogenization heat treatment; the homogenization heat treatment process is as follows: the furnace gas temperature is set to 600℃ to start heating, the metal temperature reaches 580~585℃, the furnace gas temperature drops to 585℃ to start holding, the holding time is 10~16h, and after taking it out of the furnace, it is naturally cooled to room temperature.

[0017] f. Milling: Mill the aluminum alloy flat ingot with core material layer obtained in step e. The milling amount on one side of the large surface is 20-25mm, and the milling amount on the small surface is 7-10mm. After milling, a core material ingot with a thickness of 465mm is obtained (the end difference between the milling operation side and the transmission side is controlled within 1mm).

[0018] g. Grinding, polishing, brushing, and blowing: The bonding surface of the core material ingot obtained in step f is ground and polished (during the grinding and polishing process, the first pass is made with a fine abrasive wheel, and the second pass is made with a fine abrasive wheel to check the grinding and polishing, requiring comprehensive grinding and polishing without any omissions); then, a copper wire brush is used for comprehensive brushing (the surface must be uniform and without omissions after the operation), and after brushing and polishing, blowing is performed (the brushed surface and edges must be thoroughly blown, requiring no aluminum powder or other foreign matter residue), to obtain the core material layer monomer;

[0019] (II) Preparation of the leather layer:

[0020] a. Smelting: Add aluminum ingots with a purity >99.85% and process waste into the smelting furnace for heating and smelting. Control the smelting temperature in the furnace to 720-760℃. After all the raw materials in the furnace have melted, stir to remove the slag and obtain the original alloy liquid. Then add fast-melting silicon Si95 and titanium additive Ti75 for batching. The batching temperature is 725-740℃. After batching, the aluminum alloy liquid obtained by smelting meets the alloy element composition requirements of the skin layer blank in the above-mentioned high-strength composite plate.

[0021] b. Refining: The alloy liquid for the skin layer obtained in step a is refined. Before refining, aluminum bismuth alloy AL-Bi10 and aluminum strontium alloy AL-Sr10 are added. During the refining process, the refining temperature is controlled at 720-730℃ and the refining time is 40-120min. After the refining is completed, the slag is removed to obtain the refined aluminum alloy liquid for the skin layer.

[0022] The amount of aluminum-bismuth alloy AL-Bi10 added is 5-8% of the total weight of the aluminum alloy liquid obtained from smelting in step a; the amount of aluminum-strontium alloy AL-Sr10 added is 10-13% of the total weight of the aluminum alloy liquid obtained from smelting in step a.

[0023] c. Casting: The aluminum alloy liquid obtained in step b is subjected to online primary plate filtration, secondary plate filtration and online degassing in sequence. The resulting alloy liquid is then cast into aluminum alloy flat ingots.

[0024] d. Sawing: Sawing the aluminum alloy flat ingot with skin layer obtained in step c, sawing the ingot head 300-500mm and the ingot tail 100-200mm;

[0025] e. Milling: Mill the aluminum alloy flat ingot with skin layer obtained in step d. The milling amount on one side of the large face is 15-20mm, and the milling amount on the small face is 10-15mm. After milling, the skin ingot is obtained (the end difference between the milling operation side and the transmission side should be controlled within 3mm).

[0026] f. Preheating and hot rolling: The cleaned leather ingots obtained in step e are placed in a heating furnace for preheating treatment. After treatment, the leather layer rough sheet is hot rolled. The thickness and dimensional tolerance are controlled at 54.6 (0, +0.8) mm.

[0027] The preheating process is as follows: the furnace gas temperature is set to 560°C to start heating, the metal temperature reaches 530-550°C, the furnace gas temperature drops to 550°C to start holding the temperature, the holding time is 2-4 hours, and the furnace exit temperature is 490-520°C.

[0028] The hot-rolled sheet process sets a ratio of 10.5% to 11%, where the ratio = (hot-rolled skin layer rough sheet thickness / (core material net ingot thickness + hot-rolled skin layer rough sheet thickness)) × 100%.

[0029] g. Pre-stretching and stabilization: The rough sheet material obtained in step f is pre-stretched with a stretching rate of 0.2-0.5% (pre-stretching ensures flatness); then stabilization treatment is performed. The stabilization treatment process is as follows: the furnace gas temperature is set to 210℃ to start heating, the metal temperature reaches 180-200℃, the furnace gas temperature drops to 200℃ to start heat preservation, and the heat preservation time is 18-20 hours.

[0030] h. Precision sawing: Precision saw the leather layer board obtained in step g; during the precision sawing process, control the length of the leather layer board at both ends to be less than the original length of the core material spindle by 100mm; control the width of the leather layer board at both ends to be less than the edge line of the large surface of the core material spindle by 10mm.

[0031] i. Grinding, polishing, and blowing: The bonding surface of the leather layer cut board obtained in step h is ground and polished by rotating a grinding machine (the grinding and polishing should be thorough and there should be no missed areas). Then, it is blown (the blowing should be thorough) to obtain the leather layer monomer [the ratio of the obtained leather layer monomer is 10.5-10.6%, and the total thickness is 520mm. The ratio = leather layer monomer thickness / (core material monomer thickness + leather layer monomer thickness) × 100%];

[0032] (III) Preparation of high-strength composite panels:

[0033] a. Welding:

[0034] The leather layer unit obtained in step (II) is subjected to "lifting plate welding". Lifting plates are symmetrically welded at the four corners, for a total of 4 sets (to facilitate the lifting operation, to protect the large surface of the leather layer unit during the welding process, and to grind and polish the contact parts between the lifting plate and the lifting strap to ensure smoothness); then the bonding surfaces of the leather layer unit and the core unit are cleaned again, and then welded in front of the furnace; after welding, "lifting plates are removed" (protection is taken during the removal process to prevent welding slag from falling off), then "welding slag cleaning and ingot flipping" (the edge welding slag is ground and cleaned, the milling machine roller is cleaned, and then the ingot flipping operation is performed to ensure that the leather layer unit is on the top after exiting the heating furnace), then "re-grinding and polishing treatment" (brushes, scratches, and surface aluminum powder are ground, polished, and cleaned, and then temporarily placed), and the welded ingot is obtained after the treatment;

[0035] b. Preheating: The welded ingot obtained in step a is bound together with two aluminum wires at each end for secondary protection against cracking, and then preheated.

[0036] The preheating process is as follows: the furnace gas temperature is set to 540°C to start heating, the metal temperature reaches 480-520°C, the furnace gas temperature drops to 520°C to start holding the temperature for 2-4 hours, and then the metal is taken out of the furnace at a temperature of 480-520°C.

[0037] c. Composite hot rolling (monomer deviation control of the skin layer, and the inclination of the rolling roll gap are controlled within -0.7mm).

[0038] (Inner): The welded ingot obtained in step b is hot rolled 32 times to obtain an 8.0mm hot composite billet coil, which is then naturally cooled.

[0039] d. Cold rolling: The hot composite billet obtained in step c is cooled to room temperature and then cold rolled. After 5 passes of cold rolling, a cold rolled finished coil with a thickness of 0.8 to 1.2 mm is obtained and cooled after being removed from the machine.

[0040] e. Cleaning: The cold-rolled finished coil obtained in step d is subjected to tension straightening and cleaning treatment. The cleaning water temperature is 50℃.

[0041] Linear speed is 70–85 m / min, elongation is 0–0.3%;

[0042] f. O-state annealing: The coil obtained after cleaning in step e is subjected to O-state annealing. The annealing regime is as follows: the furnace gas temperature is set to 460℃ to start heating, the metal temperature reaches 330~350℃, the furnace gas temperature drops to 355℃ to start holding, and the holding time is 3~4h. After holding, the coil is taken out of the furnace.

[0043] g. Slitting and cross-cutting: Cool the roll material obtained after O-state annealing to below 40°C, and then perform slitting and cross-cutting.

[0044] h. Packaging: The boards obtained after cross-cutting are stacked and packaged to obtain high-strength composite boards.

[0045] According to the above-mentioned preparation method of high-strength composite plate for liquid cooling plate of new energy vehicle battery, in step (I) smelting process, the mass percentage of the process waste added is ≤40%; the process waste is 3003 alloy inner-turn edge cutting waste, head and tail material, and the alloy element composition of the process waste is Si 0~0.6%, Fe 0~0.7%, Cu 0.05~0.2%, Mn 1.0~1.5%, Mg 0~0.05%, Cr 0~0.05%, Zn 0~0.1%, Ti 0~0.05%, with the balance being Al and unavoidable impurities.

[0046] According to the above-mentioned preparation method of high-strength composite plate for liquid cooling plate of new energy vehicle battery, in step (I) casting process, the specifications of the filter plates in the first-stage plate filter and the second-stage plate filter are 40ppi and 50ppi respectively; the hydrogen content in the aluminum alloy liquid obtained after filtration is <0.15ml / 100g (Al); the temperature of the static furnace before casting is 715±5℃; the temperature of the aluminum liquid in the degassing box is 690±5℃; the online grain refiner is AL-5Ti-1B titanium wire; the stable casting speed is 46mm / min; after casting, the ingot is lifted after water cooling for 30-40min.

[0047] According to the above-mentioned preparation method of high-strength composite plate for liquid cooling plate of new energy vehicle battery, in step (II) smelting process, the mass percentage of the process waste added is ≤40%; the process waste is 4343 alloy inner turning edge cutting waste, head and tail material, and the alloy element composition of the process waste is Si 6.8~8.2%, Fe 0~0.8%, Cu 0~0.25%, Mn 0~0.1%, Mg 0~0.05%, Cr 0~0.05%, Zn 0~0.2%, Ti 0~0.05%, with the balance being Al and unavoidable impurities.

[0048] According to the above-mentioned preparation method of high-strength composite plate for liquid cooling plate of new energy vehicle battery, in step (II) casting process, the filter plate specifications in the first-stage plate filter and the second-stage plate filter are both 40ppi; the hydrogen content in the aluminum alloy liquid obtained after filtration is <0.15ml / 100g (Al); the temperature of the static furnace before casting is 690~705℃; the temperature of the aluminum liquid in the degassing box is 680±5℃; the online grain refiner is AL-5Ti-0.2B titanium wire; the stable casting speed is 35mm / min; after casting is completed, the ingot is lifted after water cooling for 30~40min.

[0049] According to the above-mentioned preparation method of high-strength composite material for liquid cooling plate of new energy vehicle battery, in step (iii) welding process, the bonding surface of the skin layer unit is 40mm narrower than that of the core layer unit, with a 20mm allowance on each side; the bonding surface of the skin layer unit is 200mm shorter than that of the core layer unit, with a 100mm allowance on each side; the bonding surface of the skin layer unit is polished and bonded to the core layer unit, with corresponding structural dimensions; after bonding, the edge lines of the skin layer unit are intermittently welded in the length direction, each segment being 200mm; the width direction is welded to the 200mm range at both ends, and the remaining middle parts are not welded.

[0050] According to the above-mentioned preparation method of high-strength composite sheet for liquid cooling plate of new energy vehicle battery, in the composite hot rolling process described in step (iii): during the first to fifth passes of hot rolling, the emulsion is not opened, and the rolling force is controlled according to the setting of 100 tons. The reduction per pass is ≤1mm and the rolling speed is ≤0.5m / s. In the first pass, the roll gap is opened by 550mm, the middle of the ingot is transported to the middle of the roll gap of the work roll, and the roll gap is slowly pressed down. When the rolling force reaches no more than 100 tons, the roll gap is stopped, and the rolling is slowly rolled from the middle to one end at a speed ≤0.2mm / s (the end of the skin layer does not leave the roll gap, and then...). (After reversing and rolling the other half, the roll gap is removed). Passes 2-5: Based on the first roll gap, each reduction is ≤1mm, rolling force is 100T, and speed is ≤0.3m / s. Rolling is carried out, and the roll gap is removed in each pass. Passes 6-8: Without opening the emulsion, rolling is carried out according to the rolling force control, with a reduction of ≤10mm and rolling speed of ≤0.5m / s. Passes 9-30: The emulsion is opened, and the conventional process of 3003 alloy is followed to roll an intermediate plate with a thickness of 24-25mm. Passes 31-32: The obtained intermediate plate is rolled in 2 passes with a thickness distribution of 24-25mm - 13mm - 8.0mm. The emulsion pressure is 0.3±0.05Mpa, and the final rolling temperature is 315-330℃. Finally, an 8.0mm hot composite billet coil is obtained and naturally cooled.

[0051] The positive and beneficial effects of this invention are:

[0052] 1. In the preparation method of the present invention, the proportions of trace elements such as Fe%, Si%, Cu%, Mn%, and Ti% in the core material layer are optimized, thereby improving the overall performance of the material in terms of chemical composition, such as strength, corrosion resistance, and thermal conductivity.

[0053] 2. In the preparation method of this invention, before the refining process of the skin layer, aluminum-bismuth alloy AL-Bi10 (containing 10% Bi and the remainder being pure Al powder as an additive) and aluminum-strontium alloy Al-Sr10 (containing 10% Sr and the remainder being pure Al powder as an additive) are added. The amount of strontium and bismuth added is controlled at 0.02-0.04%. The purpose is to act as a modifier, which can effectively refine the eutectic silicon and primary silicon in the skin layer alloy, improve the mechanical properties, and its modification has good long-term effect, remelting stability and anti-fading properties are relatively good.

[0054] 3. In the preparation method of this invention, the homogenization heat treatment of the core material ingot, the pre-stretching and stabilization of the skin layer sheet are intended to eliminate internal stress and avoid composite hot rolling failure caused by stress release during composite hot rolling. At the same time, the control of the end difference between the milling process and the transmission process requires the net ingot of the new material to be controlled within 1 mm. The tilt of the composite hot rolling roll gap is controlled within -0.7 mm. All of these are to avoid the core material monomer and the skin material monomer from deviating, which would ultimately lead to composite hot rolling failure. Meanwhile, the grinding, polishing, brushing and blowing of the bonding surfaces of the core material monomer and the skin material monomer are intended to ensure the flatness and cleanliness of the bonding surfaces, so as to better achieve composite hot rolling success.

[0055] 4. In the preparation method of the present invention, the composite hot rolling is divided into 1-5 passes, 6-8 passes, 9-30 passes, and 31-32 passes with different technical processes. The purpose is to eliminate gas between the bonding surfaces and ensure the success of the composite hot rolling. At the same time, the thickness of the composite hot rolled billet is set to 8.0 mm to ensure sufficient cold working deformation and thus ensure the excellent forming performance of the final material.

[0056] In summary, this invention optimizes the microstructure of the composite material by studying and optimizing core material homogenization technology, skin material flatness control technology, and hot-rolled composite rolling technology, ultimately obtaining a high-strength composite material for liquid cooling plates of new energy vehicle batteries with a stable coverage rate.

[0057] 5. The high-strength composite board prepared by the technical solution of the present invention has been tested, and the relevant performance parameters are detailed in Table 1.

[0058] Table 1. Performance test data of the high-strength composite board of the present invention

[0059] Attached Figure Description

[0060] Figure 1 A typical coating rate diagram of the high-strength composite board prepared by this invention is shown. Detailed Implementation

[0061] The present invention will be further illustrated below with reference to the embodiments, but this does not limit the scope of protection of the technical solution of the present invention.

[0062] Example 1:

[0063] This invention relates to a high-strength composite material for liquid cooling plates in new energy vehicle batteries, comprising a core layer and a skin layer. The alloy element composition of the core layer, expressed as a percentage by mass, is: Si 0.734%, Fe 0.314%, Cu 0.817%, Mn 1.360%, Mg 0.010%, Cr 0.008%, Zn 0.023%, Ti 0.026%, with the balance being Al and unavoidable impurities.

[0064] The alloy element composition of the skin layer, expressed as a percentage by mass, is as follows: Si 10.121%, Fe 0.201%, Cu 0.023%, Mn 0.0279%, Mg 0.018%, Cr 0.005%, Zn 0.007%, Ti 0.028%, with the balance being Al and unavoidable impurities.

[0065] Example 2:

[0066] The preparation method of the high-strength composite material for liquid cooling plates of new energy vehicle batteries described in Embodiment 1 of the present invention comprises the following detailed steps:

[0067] (a) Preparation of the core layer:

[0068] a. Smelting: Aluminum ingots with a purity >99.70% and process waste are added to a smelting furnace for heating and smelting. The smelting temperature in the furnace is controlled at 740-760℃. After all the raw materials in the furnace have melted, the slag is removed by stirring to obtain the original alloy liquid. Then, Al-20Mn, Al-20Si, Al-40Cu and titanium additive Ti75 are added for batching at a temperature of 730-740℃. The alloy liquid obtained after batching meets the alloy element composition requirements of the core layer in the above-mentioned high-strength composite plate.

[0069] The process waste is added at a mass percentage of 40%; the process waste is 3003 alloy inner turning edge cutting waste, head and tail material, and the alloy element composition of the process waste is: Si 0.182%, Fe 0.583%, Cu 0.116%, Mn 1.125%, Mg 0.022%, Cr 0.012%, Zn 0.0167%, Ti 0.033%, with the balance being Al and unavoidable impurities;

[0070] b. Refining: The core material layer alloy liquid obtained in step a is refined. During the refining process, the temperature is controlled at 720-730℃ and the refining time is 60min. After the refining is completed, the slag is removed and the mixture is allowed to stand for 40min.

[0071] c. Casting: The aluminum alloy liquid core material obtained after refining in step b is subjected to online primary plate filtration, secondary plate filtration, online degassing and tubular filtration in sequence. The alloy liquid obtained after filtration is cast into aluminum alloy flat ingots.

[0072] The filter plates in the primary and secondary plate filters have specifications of 40ppi and 50ppi, respectively; the hydrogen content in the aluminum alloy liquid obtained after filtration is 0.065ml / 100g (Al); the temperature of the settling furnace before casting is 718℃; the temperature of the aluminum liquid in the degassing box is 695℃; the online grain refiner is AL-5Ti-1B titanium wire; the stable casting speed is 46mm / min; the ingot is lifted after water cooling for 40 minutes after casting is completed.

[0073] d. Sawing: Sawing the aluminum alloy flat ingot with core material layer obtained in step c, sawing the ingot head 450mm, and leaving the ingot tail unsaved;

[0074] e. Homogenization heat treatment: The sawn core aluminum alloy flat ingots obtained in step d are subjected to homogenization heat treatment. The homogenization heat treatment process is as follows: the furnace gas temperature is set to 600℃ to start heating, the metal temperature reaches 580~585℃, the furnace gas temperature drops to 585℃ to start holding, the holding time is 16h, and after being taken out of the furnace, it is naturally cooled to room temperature.

[0075] f. Milling: Mill the aluminum alloy flat ingot with core material layer obtained in step e. The milling amount on one side of the large surface is 25mm, and the milling amount on the small surface is 10mm. After milling, a core material ingot with a thickness of 465mm is obtained (the end difference between the milling operation side and the transmission side is controlled within 1mm).

[0076] g. Grinding, polishing, brushing, and blowing: The bonding surface of the core material ingot obtained in step f is ground and polished (during the grinding and polishing process, the first pass is made with a fine abrasive wheel, and the second pass is made with a fine abrasive wheel to check the grinding and polishing, requiring comprehensive grinding and polishing without any omissions); then, a copper wire brush is used for comprehensive brushing (the surface must be uniform and without omissions after the operation), and after brushing and polishing, blowing is performed (the brushed surface and edges must be thoroughly blown, requiring no aluminum powder or other foreign matter residue), to obtain the core material layer monomer;

[0077] (II) Preparation of the leather layer:

[0078] a. Smelting: Add aluminum ingots with a purity >99.85% and process waste into the smelting furnace for heating and smelting. Control the smelting temperature in the furnace to 740-760℃. After all the raw materials in the furnace have melted, stir to remove the slag and obtain the original alloy liquid. Then add fast-melting silicon Si95 and titanium additive Ti75 for batching. The batching temperature is 730-740℃. After batching, the alloy liquid obtained by smelting meets the alloy element composition requirements of the skin layer blank in the above-mentioned high-strength composite plate.

[0079] The process waste is added at a mass percentage of 40%; the process waste is 4343 alloy inner turning edge cutting waste, head and tail material, and the alloy element composition of the process waste is: Si 7.437%, Fe 0.228%, Cu 0.0006%, Mn 0.0012%, Mg 0.0053%, Cr 0.0011%, Zn 0.0010%, Ti 0.018%, with the balance being Al and unavoidable impurities;

[0080] b. Refining: The alloy liquid for the skin layer obtained in step a is refined. Before refining, aluminum bismuth alloy AL-Bi10 and aluminum strontium alloy AL-Sr10 are added. During the refining process, the refining temperature is controlled at 720-730℃ and the refining time is 60min. After the refining is completed, the slag is removed to obtain the refined aluminum alloy liquid for the skin layer.

[0081] The amount of aluminum-bismuth alloy AL-Bi10 added is 5% of the total weight of the aluminum alloy liquid obtained after melting in step a; the amount of aluminum-strontium alloy AL-Sr10 added is 10% of the total weight of the aluminum alloy liquid obtained after melting in step a.

[0082] c. Casting: The aluminum alloy liquid obtained in step b is subjected to online primary plate filtration, secondary plate filtration and online degassing in sequence, and the resulting alloy liquid is cast into aluminum alloy flat ingots.

[0083] The filter plates in both the primary and secondary plate filters are 40 ppi; the hydrogen content in the resulting aluminum alloy melt after filtration is 0.070 ml / 100 g (Al); the temperature of the settling furnace before casting is 705℃; the temperature of the aluminum melt in the degassing box is 685℃; the online grain refiner is AL-5Ti-0.2B titanium wire; the stable casting speed is 35 mm / min; the ingot is lifted after 40 minutes of water cooling at the end of casting.

[0084] d. Sawing: Sawing the aluminum alloy flat ingot with skin layer obtained in step c, sawing the ingot head 450mm and the ingot tail 200mm.

[0085] e. Milling: Mill the aluminum alloy flat ingot with skin layer obtained in step d. The milling amount on one side of the large face is 20mm, and the milling amount on the small face is 15mm. After milling, the skin ingot is obtained (the end difference between the milling operation side and the transmission side should be controlled within 3mm).

[0086] f. Preheating and hot rolling: The cleaned leather ingots obtained in step e are placed in a heating furnace for preheating treatment, and then the leather layer rough sheet is hot rolled. The thickness and dimensional tolerance are controlled at 54.6 (0, +0.8) mm.

[0087] The preheating process is as follows: the furnace gas temperature is set to 560°C to start heating, the metal temperature reaches 530-550°C, the furnace gas temperature drops to 550°C to start heat preservation, the heat preservation time is 4 hours, and the furnace exit temperature is 520°C.

[0088] The hot-rolled sheet process sets a ratio of 11%, which is calculated as: (Height of hot-rolled skin layer rough sheet / (Net thickness of core material + Thickness of hot-rolled skin layer rough sheet)) × 100%.

[0089] g. Pre-stretching and stabilization: The rough sheet material obtained in step f is pre-stretched with a stretching rate of 0.5% (pre-stretching ensures flatness); then it is stabilized. The stabilization process is as follows: the furnace gas temperature is set to 210℃ to start heating, the metal temperature reaches 180-200℃, the furnace gas temperature drops to 200℃ to start heat preservation, and heat preservation is carried out for 20 hours.

[0090] h. Precision sawing: Precision saw the leather layer board obtained in step g; during the precision sawing process, control the length of the leather layer board at both ends to be less than the original length of the core material spindle by 100mm; control the width of the leather layer board at both ends to be less than the edge line of the large surface of the core material spindle by 10mm.

[0091] i. Polishing, brushing, and blowing: The bonding surface of the leather layer cut board obtained in step h is polished and brushed using a rotating polishing machine (the polishing and brushing must be thorough and without any missed areas). Then, it is blown (the blowing must be thorough) to obtain the leather layer monomer [the ratio of the obtained leather layer monomer is 10.5%, the total thickness is 520mm, the total thickness is the sum of the thickness of the core layer monomer and the leather layer monomer, the ratio = leather layer monomer thickness / (core layer monomer thickness + leather layer monomer thickness) × 100%];

[0092] (III) Preparation of high-strength composite panels:

[0093] a. Welding:

[0094] The leather layer unit obtained in step (II) is subjected to "lifting plate welding". Lifting plates are symmetrically welded at the four corners, for a total of 4 sets (to facilitate the lifting operation, to protect the large surface of the leather layer unit during the welding process, and to grind and polish the contact parts between the lifting plate and the lifting strap to ensure smoothness); then the bonding surfaces of the leather layer unit and the core unit are cleaned again, and then welded in front of the furnace; after welding, "lifting plates are removed" (protection is taken during the removal process to prevent welding slag from falling off), then "welding slag cleaning and ingot flipping" (the edge welding slag is ground and cleaned, the milling machine roller is cleaned, and then the ingot flipping operation is performed to ensure that the leather layer unit is on the top after exiting the heating furnace), then "re-grinding and polishing treatment" (brushes, scratches, and surface aluminum powder are ground, polished, and cleaned, and then temporarily placed), and the welded ingot is obtained after the treatment;

[0095] During the welding process: the leather layer unit is 40mm narrower than the core layer unit on the bonding surface, with a 20mm allowance on each side; the leather layer unit is 200mm shorter than the core layer unit on the bonding surface, with a 100mm allowance on each side; the leather layer unit is polished and bonded to the core layer unit on the bonding surface, with corresponding structural dimensions; after bonding, the leather layer unit is intermittently welded along the length of the bonding surface, with each segment being 200mm; the width direction is welded to the two ends within a 200mm range, with the remaining middle parts left unwelded.

[0096] b. Preheating: The welded ingot obtained in step a is bound together at the head and tail with two aluminum wires for secondary protection against cracking. Then, a preheating treatment is performed. The preheating treatment procedure is as follows: the furnace gas temperature is set to 540℃ to start heating, the metal temperature reaches 480-520℃, the furnace gas temperature drops to 520℃ to start holding the temperature for 4 hours, and then the metal is taken out of the furnace at a temperature of 520℃.

[0097] c. Composite hot rolling (monomer deviation control of the skin layer, and the inclination of the rolling roll gap are controlled within -0.7mm).

[0098] (Inner): The welded ingot obtained in step b is hot rolled 32 times to obtain an 8.0mm hot composite billet coil, which is then naturally cooled.

[0099] During the first five hot rolling passes, the emulsion is not opened, and the rolling force is controlled according to a set force of 100 tons. Each pass reduces the thickness by 1 mm, and the rolling speed is 0.5 m / s. In the first pass, the roll gap is opened to 550 mm. The middle of the ingot is transported to the middle of the work roll gap, and the roll gap is slowly lowered until the rolling force reaches no more than 100 tons. Rolling continues slowly from the middle to one end at a speed of 0.2 mm / s (the end of the skin layer does not exit the roll gap; then the other half is rolled in the reverse direction before exiting the roll gap). For the second to fifth passes: based on the first roll gap, each pass reduces the thickness by 1 mm, with a rolling force of 100 tons and a speed of... Rolling is performed at a speed of 0.3 m / s, with roll gaps in each pass; Passes 6-8: No emulsion is opened, rolling is carried out according to the rolling force control, with a reduction of 10 mm and a rolling speed of 0.5 m / s; Passes 9-30: Emulsion is opened, and the process is carried out according to the conventional process of 3003 alloy to obtain an intermediate plate with a thickness of 25 mm; Passes 31-32: The obtained intermediate plate is rolled in 2 passes, with a pass thickness distribution of 25 mm-13 mm-8.0 mm, an emulsion pressure of 0.3±0.05 MPa, and a final rolling temperature of 330℃, finally obtaining an 8.0 mm hot composite billet coil, which is then naturally cooled;

[0100] d. Cold rolling: The hot composite billet obtained in step c is cooled to room temperature and then cold rolled. After 5 passes of cold rolling, the pass distribution is: 8.0-5.5-3.5-2.2-1.5-1.2mm, a cold rolled finished coil with a thickness of 1.2mm is obtained and cooled after being removed from the machine.

[0101] e. Cleaning: The cold-rolled finished coil obtained in step d is subjected to tension straightening and cleaning treatment. The cleaning water temperature is 50℃.

[0102] The linear velocity is 85 m / min, and the elongation is 0.25%.

[0103] f. O-state annealing: The coil obtained after cleaning in step e is subjected to O-state annealing. The annealing regime is as follows: the furnace gas temperature is set to 460℃ to start heating, the metal temperature reaches 330~350℃, the furnace gas temperature is reduced to 355℃ to start holding, and the holding time is 4 hours. After holding, the coil is removed from the furnace.

[0104] g. Slitting and cross-cutting: Cool the roll material obtained after O-state annealing to below 40°C, and then perform slitting and cross-cutting.

[0105] h. Packaging: The boards obtained after cross-cutting are stacked and packaged to obtain high-strength composite boards.

[0106] The mechanical comparison data of the high-strength composite material for liquid cooling plates of new energy vehicle batteries prepared in Example 2 of this invention are detailed in Table 2.

[0107] Table 2. Performance test data of the high-strength composite board product prepared in Example 2.

[0108]

[0109] Example 3:

[0110] This invention relates to a high-strength composite material for liquid cooling plates in new energy vehicle batteries, comprising a core layer and a skin layer. The alloy element composition of the core layer, expressed as a percentage by mass, is: Si 0.724%, Fe 0.380%, Cu 0.832%, Mn 1.339%, Mg 0.018%, Cr 0.004%, Zn 0.026%, Ti 0.022%, with the balance being Al and unavoidable impurities.

[0111] The alloy element composition of the skin layer, expressed as a percentage by mass, is as follows: Si 10.025%, Fe 0.193%, Cu 0.029%, Mn 0.028%, Mg 0.028%, Cr 0.004%, Zn 0.006%, Ti 0.028%, with the balance being Al and unavoidable impurities.

[0112] Example 4:

[0113] The preparation method of the high-strength composite material for liquid cooling plates of new energy vehicle batteries described in Embodiment 3 of the present invention comprises the following detailed steps:

[0114] (a) Preparation of the core layer:

[0115] a. Smelting: Aluminum ingots with a purity >99.70% and process waste are added to a smelting furnace for heating and smelting. The smelting temperature in the furnace is controlled at 735-750℃. After all the raw materials in the furnace have melted, the slag is removed by stirring to obtain the original alloy liquid. Then, Al-20Mn, Al-20Si, Al-40Cu and titanium additive Ti75 are added for batching at a temperature of 725-735℃. The alloy liquid obtained after batching meets the alloy element composition requirements of the core layer in the above-mentioned high-strength composite plate.

[0116] The process waste is added at a mass percentage of 20%; the process waste is 3003 alloy inner turning edge cutting waste, head and tail material, and the alloy element composition of the process waste is: Si 0.187%, Fe 0.582%, Cu 0.111%, Mn 1.154%, Mg 0.023%, Cr 0.013%, Zn 0.0185%, Ti 0.033%, with the balance being Al and unavoidable impurities;

[0117] b. Refining: The core material layer alloy liquid obtained in step a is refined. During the refining process, the temperature is controlled at 720-730℃ and the refining time is 50min. After the refining is completed, the slag is removed and the mixture is allowed to stand for 30min.

[0118] c. Casting: The aluminum alloy liquid core material obtained after refining in step b is subjected to online primary plate filtration, secondary plate filtration, online degassing and tubular filtration in sequence. The alloy liquid obtained after filtration is cast into aluminum alloy flat ingots.

[0119] The filter plates in the primary and secondary plate filters have specifications of 40ppi and 50ppi, respectively; the hydrogen content in the aluminum alloy liquid obtained after filtration is 0.068ml / 100g (Al); the temperature of the settling furnace before casting is 715℃; the temperature of the aluminum liquid in the degassing box is 690℃; the online grain refiner is AL-5Ti-1B titanium wire; the stable casting speed is 46mm / min; the ingot is lifted after water cooling for 35 minutes after casting is completed.

[0120] d. Sawing: Sawing the aluminum alloy flat ingot with core material layer obtained in step c, sawing the ingot head 350mm, and leaving the ingot tail unsaved;

[0121] e. Homogenization heat treatment: The sawn core aluminum alloy flat ingot obtained in step d is subjected to homogenization heat treatment; the homogenization heat treatment process is as follows: the furnace gas temperature is set to 600℃ to start heating, the metal temperature reaches 580~585℃, the furnace gas temperature drops to 585℃ to start holding, the holding time is 13h, and after taking it out of the furnace, it is naturally cooled to room temperature.

[0122] f. Milling: Mill the aluminum alloy flat ingot with core material layer obtained in step e. The milling amount on one side of the large face is 23mm and the milling amount on the small face is 8.5mm. After milling, a core material ingot with a thickness of 465mm is obtained (the end difference between the milling operation side and the transmission side is controlled within 1mm).

[0123] g. Grinding, polishing, brushing, and blowing: The bonding surface of the core material ingot obtained in step f is ground and polished (during the grinding and polishing process, the first pass is made with a fine abrasive wheel, and the second pass is made with a fine abrasive wheel to check the grinding and polishing, requiring comprehensive grinding and polishing without any omissions); then, a copper wire brush is used for comprehensive brushing (the surface must be uniform and without omissions after the operation), and after brushing and polishing, blowing is performed (the brushed surface and edges must be thoroughly blown, requiring no aluminum powder or other foreign matter residue), to obtain the core material layer monomer;

[0124] (II) Preparation of the leather layer:

[0125] a. Smelting: Add aluminum ingots with a purity >99.85% and process waste into the smelting furnace for heating and smelting. Control the smelting temperature in the furnace to 735-750℃. After all the raw materials in the furnace have melted, stir to remove the slag and obtain the original alloy liquid. Then add fast-melting silicon Si95 and titanium additive Ti75 for batching at a temperature of 725-735℃. After batching, ensure that the alloy liquid obtained from smelting meets the alloy element composition requirements of the skin layer blank in the above-mentioned high-strength composite plate.

[0126] The process waste is added at a mass percentage of 20%; the process waste is 4343 alloy inner turning edge cutting waste, head and tail material, and the alloy element composition of the process waste is: Si 7.456%, Fe 0.230%, Cu 0.0005%, Mn 0.0011%, Mg 0.0052%, Cr 0.0012%, Zn 0.0012%, Ti 0.019%, with the balance being Al and unavoidable impurities;

[0127] b. Refining: The alloy liquid for the skin layer obtained in step a is refined. Before refining, aluminum bismuth alloy AL-Bi10 and aluminum strontium alloy AL-Sr10 are added. During the refining process, the refining temperature is controlled at 720-730℃ and the refining time is 50min. After the refining is completed, the slag is removed to obtain the refined aluminum alloy liquid for the skin layer.

[0128] The amount of aluminum-bismuth alloy AL-Bi10 added is 5% of the total weight of the molten aluminum alloy obtained after melting in step a; the amount of aluminum-strontium alloy AL-Sr10 added is 10% of the total weight of the molten aluminum alloy obtained after melting in step a.

[0129] c. Casting: The aluminum alloy liquid obtained in step b is subjected to online primary plate filtration, secondary plate filtration and online degassing in sequence, and the resulting alloy liquid is cast into aluminum alloy flat ingots.

[0130] The filter plates in both the primary and secondary plate filters are 40 ppi; the hydrogen content in the resulting aluminum alloy melt after filtration is 0.075 ml / 100 g (Al); the temperature of the settling furnace before casting is 698℃; the temperature of the aluminum melt in the degassing box is 680℃; the online grain refiner is AL-5Ti-0.2B titanium wire; the stable casting speed is 35 mm / min; the ingot is lifted after 35 minutes of water cooling at the end of casting.

[0131] d. Sawing: Sawing the aluminum alloy flat ingot with skin layer obtained in step c, sawing the ingot head 350mm and the ingot tail 150mm.

[0132] e. Milling: Mill the aluminum alloy flat ingot with skin layer obtained in step d. The milling amount on one side of the large face is 18mm and the milling amount on the small face is 13mm. After milling, the skin ingot is obtained (the end difference between the milling operation side and the transmission side should be controlled within 3mm).

[0133] f. Preheating and hot rolling: The cleaned leather ingots obtained in step e are placed in a heating furnace for preheating treatment, and then the leather layer rough sheet is hot rolled. The thickness and dimensional tolerance are controlled at 54.6 (0, +0.8) mm.

[0134] The preheating process is as follows: the furnace gas temperature is set to 560°C to start heating, the metal temperature reaches 530-550°C, the furnace gas temperature drops to 550°C to start heat preservation, the heat preservation time is 3 hours, and the furnace exit temperature is 505°C.

[0135] The hot-rolled sheet process sets a ratio of 10.8%, where the ratio = (hot-rolled skin layer rough sheet thickness / (core material net ingot thickness + hot-rolled skin layer rough sheet thickness)) × 100%;

[0136] g. Pre-stretching and stabilization: The rough sheet material obtained in step f is pre-stretched with a stretching rate of 0.35% (pre-stretching ensures flatness); then it is stabilized. The stabilization process is as follows: the furnace gas temperature is set to 210℃ to start heating, the metal temperature reaches 180-200℃, the furnace gas temperature drops to 200℃ to start heat preservation, and heat preservation is carried out for 19 hours.

[0137] h. Precision sawing: Precision saw the leather layer board obtained in step g; during the precision sawing process, control the length of the leather layer board at both ends to be less than the original length of the core material spindle by 100mm; control the width of the leather layer board at both ends to be less than the edge line of the large surface of the core material spindle by 10mm.

[0138] i. Polishing, brushing, and blowing: The bonding surface of the leather layer cut board obtained in step h is polished and brushed using a rotating polishing machine (the polishing and brushing must be thorough and without any missed areas). Then, it is blown (the blowing must be thorough) to obtain the leather layer monomer [the ratio of the obtained leather layer monomer is 10.5%, the total thickness is 520mm, the total thickness is the sum of the thickness of the core layer monomer and the leather layer monomer, the ratio = leather layer monomer thickness / (core layer monomer thickness + leather layer monomer thickness) × 100%];

[0139] (III) Preparation of high-strength composite panels:

[0140] a. Welding:

[0141] The leather layer unit obtained in step (II) is subjected to "lifting plate welding". Lifting plates are symmetrically welded at the four corners, for a total of 4 sets (to facilitate the lifting operation, to protect the large surface of the leather layer unit during the welding process, and to grind and polish the contact parts between the lifting plate and the lifting strap to ensure smoothness); then the bonding surfaces of the leather layer unit and the core unit are cleaned again. After cleaning, the in-furnace welding is performed. After welding, the "lifting plate is removed" (protection is taken during the removal process to prevent welding slag from falling off). Then, "welding slag cleaning and ingot flipping" is performed (the edge welding slag is ground and cleaned, the milling machine roller is cleaned, and the ingot flipping operation is performed to ensure that the leather layer unit is on the top after exiting the heating furnace). Then, "re-grinding and polishing treatment" is performed (brushes, scratches, and surface aluminum powder are ground, polished, and cleaned, and then temporarily placed). After processing, the welded ingot is obtained.

[0142] During the welding process, the surface of the leather layer unit is 40mm narrower than that of the core layer unit, with a 20mm allowance on each side; the length of the leather layer unit is 200mm shorter than that of the core layer unit, with a 100mm allowance on each side; the polished surfaces of the leather layer unit and the core layer unit are aligned and their structural dimensions correspond; after bonding, the edges of the leather layer unit and the core layer unit are intermittently welded along the length, with each segment being 200mm; the width is welded within a 200mm range at both ends, with the remaining middle parts left unwelded.

[0143] b. Preheating: The welded ingot obtained in step a is bound together at the head and tail with two aluminum wires each for secondary protection against cracking; then it is preheated.

[0144] The preheating process is as follows: the gas temperature is set to 540°C to start heating, the metal temperature reaches 480-520°C, the furnace gas temperature drops to 520°C to start holding the temperature for 3 hours, and then the metal is taken out of the furnace at a temperature of 500°C.

[0145] c. Composite hot rolling (monomer deviation control of the skin layer, and the inclination of the rolling roll gap are controlled within -0.7mm).

[0146] (Inner): The welded ingot obtained in step b is hot rolled 32 times to obtain an 8.0mm hot composite billet coil, which is then naturally cooled.

[0147] During the first five hot rolling passes, the emulsion is not opened, and the rolling force is controlled according to a set force of 100 tons. Each pass reduces the thickness by 1 mm, and the rolling speed is 0.4 m / s. In the first pass, the roll gap is opened to 550 mm. The middle of the ingot is transported to the middle of the work roll gap, and the roll gap is slowly lowered until the rolling force reaches no more than 100 tons. Rolling continues slowly from the middle to one end at a speed of 0.2 mm / s (the end of the skin layer does not exit the roll gap; then the other half is rolled in the reverse direction before exiting the roll gap). For the second to fifth passes: based on the first roll gap, each pass reduces the thickness by 1 mm, with a rolling force of 100 tons and a speed of... Rolling is performed at a speed of 0.3 m / s, with roll gaps in each pass; Passes 6-8: No emulsion is opened, rolling is carried out according to the rolling force control, with a reduction of 9 mm and a rolling speed of 0.4 m / s; Passes 9-30: Emulsion is opened, and the process is carried out according to the conventional process of 3003 alloy to obtain an intermediate plate with a thickness of 24 mm; Passes 31-32: The obtained intermediate plate is rolled in 2 passes, with a pass thickness distribution of 24 mm-13 mm-8.0 mm, an emulsion pressure of 0.3±0.05 MPa, and a final rolling temperature of 323℃, finally obtaining an 8.0 mm hot composite billet coil, which is then naturally cooled;

[0148] d. Cold rolling: The hot composite billet obtained in step c is cooled to room temperature and then cold rolled. After 5 passes of cold rolling, the pass distribution is: 8.0mm-5.5mm-3.5mm-2.2mm-1.5mm-1.0mm, a cold rolled finished coil with a thickness of 1.0mm is obtained and cooled after being removed from the machine.

[0149] e. Cleaning: The cold-rolled finished coil obtained in step d is subjected to tension straightening and cleaning treatment. The cleaning water temperature is 50℃.

[0150] The linear velocity is 80 m / min, and the elongation is 0.15%.

[0151] f. O-state annealing: The coil obtained after cleaning in step e is subjected to O-state annealing. The annealing regime is as follows: the furnace gas temperature is set to 460℃ to start heating, the metal temperature reaches 330~350℃, the furnace gas temperature drops to 355℃ to start holding, and the holding time is 3.5h. After holding, the coil is removed from the furnace.

[0152] g. Slitting and cross-cutting: Cool the roll material obtained after O-state annealing to below 40°C, and then perform slitting and cross-cutting.

[0153] h. Packaging: The boards obtained after cross-cutting are stacked and packaged to obtain high-strength composite boards.

[0154] The mechanical comparison data of the high-strength composite material for liquid cooling plates of new energy vehicle batteries prepared in Example 4 of this invention are detailed in Table 3.

[0155] Table 3. Performance test data of the high-strength composite board product prepared in Example 4 of this paper.

[0156]

[0157] Example 5:

[0158] This invention relates to a high-strength composite material for liquid cooling plates in new energy vehicle batteries, comprising a core layer and a skin layer. The alloy element composition of the core layer, expressed as a percentage by mass, is: Si 0.742%, Fe 0.389%, Cu 0.845%, Mn 1.365%, Mg 0.020%, Cr 0.008%, Zn 0.019%, Ti 0.028%, with the balance being Al and unavoidable impurities.

[0159] The alloy element composition of the skin layer, expressed as a percentage by mass, is as follows: Si 10.045%, Fe 0.189%, Cu 0.035%, Mn 0.032%, Mg 0.020%, Cr 0.006%, Zn 0.005%, Ti 0.024%, with the balance being Al and unavoidable impurities.

[0160] Example 6:

[0161] The preparation method of the high-strength composite material for liquid cooling plates of new energy vehicle batteries described in Embodiment 5 of the present invention comprises the following detailed steps:

[0162] (a) Preparation of the core layer:

[0163] a. Smelting: Add aluminum ingots with a purity >99.70% to the smelting furnace for heating and smelting. Control the smelting temperature in the furnace to 720-745℃. After all the raw materials in the furnace have melted, stir to remove the slag and obtain the original alloy liquid. Then add Al-20Mn, Al-20Si, Al-40Cu and titanium additive Ti75 for batching. The batching temperature is 725-740℃. After batching, make the alloy liquid obtained by smelting meet the alloy element composition requirements of the core layer of the above-mentioned high-strength composite plate.

[0164] b. Refining: The core material layer alloy liquid obtained in step a is refined. During the refining process, the temperature is controlled at 720-730℃ and the refining time is 40 minutes. After the refining is completed, the slag is removed and the mixture is allowed to stand for 20 minutes.

[0165] c. Casting: The aluminum alloy liquid core material obtained after refining in step b is subjected to online primary plate filtration, secondary plate filtration, online degassing and tubular filtration in sequence. The alloy liquid obtained after filtration is cast into aluminum alloy flat ingots.

[0166] The filter plates in the primary and secondary plate filters have specifications of 40ppi and 50ppi, respectively; the hydrogen content in the aluminum alloy liquid obtained after filtration is 0.069ml / 100g (Al); the temperature of the settling furnace before casting is 710℃; the temperature of the aluminum liquid in the degassing box is 685℃; the online grain refiner is AL-5Ti-1B titanium wire; the stable casting speed is 46mm / min; the ingot is lifted after water cooling for 30 minutes after casting is completed.

[0167] d. Sawing: Sawing the aluminum alloy flat ingot with core material layer obtained in step c, sawing the ingot head 300mm, and leaving the ingot tail unsaved;

[0168] e. Homogenization heat treatment: The sawn core aluminum alloy flat ingots obtained in step d are subjected to homogenization heat treatment; the homogenization heat treatment process is as follows: the furnace gas temperature is set to 600℃ to start heating, the metal temperature reaches 580~585℃, the furnace gas temperature drops to 585℃ to start holding, the holding time is 10h, and after taking it out of the furnace, it is naturally cooled to room temperature.

[0169] f. Milling: Mill the aluminum alloy flat ingot of core material layer obtained in step e. The milling amount on one side of the large surface is 20mm and the milling amount on the small surface is 7mm. After milling, a core material ingot with a thickness of 465mm is obtained (the end difference between the milling operation side and the transmission side is controlled within 1mm).

[0170] g. Grinding, polishing, brushing, and blowing: The bonding surface of the core material ingot obtained in step f is ground and polished (during the grinding and polishing process, the first pass is made with a fine abrasive wheel, and the second pass is made with a fine abrasive wheel to check the grinding and polishing, requiring comprehensive grinding and polishing without any omissions); then, a copper wire brush is used for comprehensive brushing (the surface must be uniform and without omissions after the operation), and after brushing and polishing, blowing is performed (the brushed surface and edges must be thoroughly blown, requiring no aluminum powder or other foreign matter residue), to obtain the core material layer monomer;

[0171] (II) Preparation of the leather layer:

[0172] a. Smelting: Add aluminum ingots with a purity >99.85% to the smelting furnace for heating and smelting. Control the smelting temperature in the furnace to 720-745℃. After all the raw materials in the furnace have melted, stir to remove the slag and obtain the original alloy liquid. Then add fast-melting silicon Si95 and titanium additive Ti75 for batching. The batching temperature is 725-740℃. After batching, make the alloy liquid obtained by smelting meet the alloy element composition requirements of the skin layer blank in the above-mentioned high-strength composite plate.

[0173] b. Refining: The alloy liquid for the skin layer obtained in step a is refined. Before refining, aluminum bismuth alloy AL-Bi10 and aluminum strontium alloy AL-Sr10 are added. During the refining process, the refining temperature is controlled at 720-730℃ and the refining time is 40min. After the refining is completed, the slag is removed to obtain the refined aluminum alloy liquid for the skin layer.

[0174] The amount of aluminum-bismuth alloy AL-Bi10 added is 5% of the total weight of the aluminum alloy liquid obtained after melting in step a; the amount of aluminum-strontium alloy AL-Sr10 added is 10% of the total weight of the aluminum alloy liquid obtained after melting in step a.

[0175] c. Casting: The aluminum alloy liquid obtained in step b is subjected to online primary plate filtration, secondary plate filtration and online degassing in sequence, and the resulting alloy liquid is cast into aluminum alloy flat ingots.

[0176] The filter plates in both the primary and secondary plate filters are 40 ppi; the hydrogen content in the resulting aluminum alloy melt after filtration is 0.080 ml / 100 g (Al); the temperature of the settling furnace before casting is 690℃; the temperature of the aluminum melt in the degassing box is 675℃; the online grain refiner is AL-5Ti-0.2B titanium wire; the stable casting speed is 35 mm / min; the ingot is lifted after 30 minutes of water cooling at the end of casting.

[0177] d. Sawing: Sawing the aluminum alloy flat ingot with skin layer obtained in step c, sawing the ingot head 300mm and the ingot tail 100mm.

[0178] e. Milling: Mill the aluminum alloy flat ingot with skin layer obtained in step d. The milling amount on one side of the large face is 15mm and the milling amount on the small face is 10mm. After milling, the skin ingot is obtained (the end difference between the milling operation side and the transmission side should be controlled within 3mm).

[0179] f. Preheating and hot rolling: The cleaned leather ingots obtained in step e are placed in a heating furnace for preheating treatment, and then the leather layer rough sheet is hot rolled. The thickness and dimensional tolerance are controlled at 54.6 (0, +0.8) mm.

[0180] The preheating process is as follows: the furnace gas temperature is set to 560°C to start heating, the metal temperature reaches 530-550°C, the furnace gas temperature drops to 550°C to start holding the temperature for 2 hours, and the furnace exit temperature is 495°C.

[0181] The hot-rolled sheet process sets a ratio of 10.6%, where the ratio = (hot-rolled skin layer rough sheet thickness / (core material net ingot thickness + hot-rolled skin layer rough sheet thickness)) × 100%;

[0182] g. Pre-stretching and stabilization: The rough sheet material obtained in step f is pre-stretched with a stretching rate of 0.2% (pre-stretching ensures flatness); then stabilization treatment is performed. The stabilization treatment process is as follows: the furnace gas temperature is set to 210℃ to start heating, the metal temperature reaches 180-200℃, the furnace gas temperature drops to 200℃ to start heat preservation, and heat preservation is performed for 18 hours.

[0183] h. Precision sawing: Precision saw the leather layer board obtained in step g; during the precision sawing process, control the length of the leather layer board at both ends to be less than the original length of the core material spindle by 100mm; control the width of the leather layer board at both ends to be less than the edge line of the large surface of the core material spindle by 10mm.

[0184] i. Polishing, brushing, and blowing: The bonding surface of the leather layer cut board obtained in step h is polished and brushed using a rotating polishing machine (the polishing and brushing must be thorough and without any missed areas). Then, it is blown (the blowing must be thorough) to obtain the leather layer monomer [the ratio of the obtained leather layer monomer is 10.5%, the total thickness is 520mm, the total thickness is the sum of the thickness of the core layer monomer and the leather layer monomer, the ratio = leather layer monomer thickness / (core layer monomer thickness + leather layer monomer thickness) × 100%];

[0185] (III) Preparation of high-strength composite panels:

[0186] a. Welding:

[0187] The leather layer unit obtained in step (II) is subjected to "lifting plate welding". Lifting plates are symmetrically welded at the four corners, for a total of 4 sets (to facilitate the lifting operation, to protect the large surface of the leather layer unit during the welding process, and to grind and polish the contact parts between the lifting plate and the lifting strap to ensure smoothness); then the bonding surfaces of the leather layer unit and the core unit are cleaned again, and then welded in front of the furnace; after welding, "lifting plates are removed" (protection is taken during the removal process to prevent welding slag from falling off), then "welding slag cleaning and ingot flipping" (the edge welding slag is ground and cleaned, the milling machine roller is cleaned, and then the ingot flipping operation is performed to ensure that the leather layer unit is on the top after exiting the heating furnace), then "re-grinding and polishing treatment" (brushes, scratches, and surface aluminum powder are ground, polished, and cleaned, and then temporarily placed), and the welded ingot is obtained after the treatment;

[0188] During the welding process, the surface of the leather layer unit is 40mm narrower than that of the core layer unit, with a 20mm allowance on each side; the length of the leather layer unit is 200mm shorter than that of the core layer unit, with a 100mm allowance on each side; the polished surfaces of the leather layer unit and the core layer unit are aligned and their structural dimensions correspond; after bonding, the edges of the leather layer unit and the core layer unit are intermittently welded along the length, with each segment being 200mm; the width is welded within a 200mm range at both ends, with the remaining middle parts left unwelded.

[0189] b. Preheating: The welded ingot obtained in step a is bound together at the head and tail with two aluminum wires each for secondary protection against cracking; then it is preheated.

[0190] The preheating process is as follows: the gas temperature is set to 540°C to start heating, the metal temperature reaches 480-520°C, the furnace gas temperature drops to 520°C to start holding the temperature for 2 hours, and then the metal is taken out of the furnace at a temperature of 480°C.

[0191] c. Composite hot rolling (monomer deviation control of the skin layer, and the inclination of the rolling roll gap are controlled within -0.7mm).

[0192] (Inner): The welded ingot obtained in step b is hot rolled 32 times to obtain an 8.0mm hot composite billet coil, which is then naturally cooled.

[0193] During the first five hot rolling passes, the emulsion is not opened, and the rolling force is controlled according to a set force of 100 tons. Each pass reduces the thickness by 1 mm, and the rolling speed is 0.3 m / s. In the first pass, the roll gap is opened (550 mm), and the middle of the ingot is transported to the middle of the work roll gap. The roll gap is slowly lowered until the rolling force reaches no more than 100 tons, at which point the rolling is stopped. Rolling continues slowly from the middle to one end at a speed of 0.2 mm / s (the end of the skin layer does not exit the roll gap; then the other half is rolled in the reverse direction before exiting the roll gap). For the second to fifth passes: based on the first roll gap, each pass reduces the thickness by 1 mm, with a rolling force of 100 tons and a speed of... Rolling is performed at 0.3 m / s, with roll gaps in each pass; Passes 6-8: No emulsion is opened, rolling is carried out according to the rolling force control, with a reduction of 8 mm and a rolling speed of 0.3 m / s; Passes 9-30: Emulsion is opened, and the process is carried out according to the conventional process of 3003 alloy, resulting in an intermediate plate with a thickness of 24.5 mm; Passes 31-32: The obtained intermediate plate is rolled in 2 passes, with a pass thickness distribution of 24.5 mm-13 mm-8.0 mm, an emulsion pressure of 0.3 ± 0.05 MPa, and a final rolling temperature of 315℃, finally obtaining an 8.0 mm hot composite billet coil, which is then naturally cooled;

[0194] d. Cold rolling: The hot composite billet obtained in step c is cooled to room temperature and then cold rolled. After 5 passes of cold rolling, the pass distribution is: 8.0mm-5.2mm-3.2mm-2.0mm-1.35mm-0.9mm, a cold rolled finished coil with a thickness of 0.9mm is obtained and cooled after being removed from the machine.

[0195] e. Cleaning: The cold-rolled finished coil obtained in step d is subjected to tension straightening and cleaning treatment. The cleaning water temperature is 50℃.

[0196] The linear velocity is 70 m / min, and the elongation is 0.1%.

[0197] f. O-state annealing: The coil obtained after cleaning in step e is subjected to O-state annealing. The annealing regime is as follows: the furnace gas temperature is set to 460℃ to start heating, the metal temperature reaches 330~350℃, the furnace gas temperature is reduced to 355℃ to start holding, and the holding time is 3 hours. After holding, the coil is removed from the furnace.

[0198] g. Slitting and cross-cutting: Cool the roll material obtained after O-state annealing to below 40°C, and then perform slitting and cross-cutting.

[0199] h. Packaging: The boards obtained after cross-cutting are stacked and packaged to obtain high-strength composite boards.

[0200] The mechanical comparison data of the high-strength composite material for liquid cooling plates of new energy vehicle batteries prepared in Example 6 of this invention are detailed in Table 4.

[0201] Table 4. Performance test data of the high-strength composite board product prepared in Example 6.

[0202] .

Claims

1. A method for preparing a high-strength composite sheet for a new energy vehicle battery liquid cooling plate, characterized by, The preparation method includes the following steps: (a) Preparation of the core layer: a1. Smelting: Aluminum ingots with a purity >99.70% and process waste are added to a smelting furnace for heating and smelting. The smelting temperature in the furnace is controlled at 720-760℃. After all the raw materials in the furnace have melted, the slag is removed by stirring to obtain the original alloy liquid. Then, at least one of Al-20Mn, Al-20Si, Al-40Cu and titanium additive Ti75 is added for batching at a temperature of 725-740℃. The alloy liquid obtained after batching meets the alloy element composition requirements of the core layer in the high-strength composite plate. The alloy element composition of the core material layer, expressed as a percentage by mass, is as follows: Si 0.6–1.2%, Fe 0–0.5%, Cu 0.7–1.1%, Mn 1.2–1.8%, Mg 0–0.03%, Cr 0–0.05%, Zn 0–0.1%, Ti 0.02–0.035%, with the balance being Al and unavoidable impurities; b1. Refining: The core material layer alloy liquid obtained in step a1 is refined. During the refining process, the temperature is controlled at 720-730℃ and the refining time is 40-120min. After the refining is completed, the slag is removed and the liquid is allowed to stand for 20-40min. c1. Casting: The aluminum alloy liquid core material obtained after refining in step b1 is subjected to online primary plate filtration, secondary plate filtration, online degassing and tubular filtration in sequence. The alloy liquid obtained after filtration is cast into aluminum alloy flat ingots. d1. Sawing: Sawing the aluminum alloy flat ingot with core material layer obtained in step c1, sawing the ingot head 300-500mm, and leaving the ingot tail unsaved; e1. Homogenization heat treatment: The sawn core aluminum alloy flat ingots obtained in step d1 are subjected to homogenization heat treatment; the homogenization heat treatment process is as follows: the furnace gas temperature is set to 600℃ to start heating, the metal temperature reaches 580~585℃, the furnace gas temperature drops to 585℃ to start holding, the holding time is 10~16h, and after taking it out of the furnace, it is naturally cooled to room temperature. f1. Milling: Mill the aluminum alloy flat ingot with core material layer obtained in step e1. The milling amount on one side of the large surface is 20-25mm, and the milling amount on the small surface is 7-10mm. After milling, a core material ingot with a thickness of 465mm is obtained. g1. Grinding, polishing, brushing, and blowing: The bonding surface of the core material ingot obtained in step f1 is ground and polished; then, a copper wire brush is used for comprehensive brushing, and after brushing, it is blown to obtain the core material layer monomer. (II) Preparation of the leather layer: a2. Smelting: Aluminum ingots with a purity >99.85% and process waste are added to a smelting furnace for heating and smelting. The smelting temperature in the furnace is controlled at 720-760℃. After all the raw materials in the furnace have melted, the slag is removed by stirring to obtain the original alloy liquid. Then, fast-melting silicon Si95 and titanium additive Ti75 are added for batching at a temperature of 725-740℃. After batching, the aluminum alloy liquid obtained by smelting meets the alloy element composition requirements of the skin layer blank in the high-strength composite plate. The alloy element composition of the skin layer, expressed as a percentage by mass, is as follows: Si 9-11%, Fe 0-0.25%, Cu 0-0.3%, Mn 0-0.05%, Mg 0-0.03%, Cr 0-0.05%, Zn 0-0.1%, Ti 0.02-0.03%, with the balance being Al and unavoidable impurities; b2. Refining: The alloy liquid for the skin layer obtained in step a2 is refined. Before refining, aluminum-bismuth alloy AL-Bi10 and aluminum-strontium alloy AL-Sr10 are added. During the refining process, the refining temperature is controlled at 720-730℃ and the refining time is 40-120min. After the refining is completed, the slag is removed to obtain the refined aluminum alloy liquid for the skin layer. The amount of aluminum-bismuth alloy AL-Bi10 added is 5-8% of the total weight of the aluminum alloy liquid obtained from smelting in step a2; the amount of aluminum-strontium alloy AL-Sr10 added is 10-13% of the total weight of the aluminum alloy liquid obtained from smelting in step a2. c2. Casting: The aluminum alloy liquid obtained in step b2 is subjected to online primary plate filtration, secondary plate filtration and online degassing in sequence. The resulting alloy liquid is then cast into aluminum alloy flat ingots. d2. Sawing: Sawing the aluminum alloy flat ingot with skin layer obtained in step c2, sawing the ingot head 300-500mm and the ingot tail 100-200mm; e2. Milling: Mill the aluminum alloy flat ingot with skin layer obtained in step d2. The milling amount on one side of the large surface is 15-20mm, and the milling amount on the small surface is 10-15mm. After milling, the clean ingot with skin layer is obtained. f2. Preheating and hot rolling: The leather ingots obtained in step e2 are placed in a heating furnace for preheating treatment. After treatment, the leather layer rough sheet is hot rolled. The thickness and dimensional tolerance are controlled at 54.6 (0, +0.8) mm. The preheating process is as follows: the furnace gas temperature is set to 560°C to start heating, the metal temperature reaches 530-550°C, the furnace gas temperature drops to 550°C to start holding the temperature, the holding time is 2-4 hours, and the furnace exit temperature is 490-520°C. The hot-rolled sheet process sets a ratio of 10.5% to 11%, where the ratio = (hot-rolled skin layer rough sheet thickness / (core material net ingot thickness + hot-rolled skin layer rough sheet thickness)) × 100%. g2. Pre-stretching and stabilization: The raw sheet material obtained in step f2 is pre-stretched with a stretching rate of 0.2-0.5%; then it is stabilized. The stabilization process is as follows: the furnace gas temperature is set to 210°C to start heating, the metal temperature reaches 180-200°C, the furnace gas temperature drops to 200°C to start heat preservation, and the heat preservation time is 18-20 hours. h2. Precision sawing: Precision sawing the leather layer board obtained in step g2; during the precision sawing process, control the length of the leather layer board at both ends to be 100mm less than the original length of the core material spindle; control the width of the leather layer board at both ends to be 10mm less than the edge line of the large surface of the core material spindle. i2. Grinding, polishing, and blowing: The bonding surface of the leather layer cut board obtained in step h2 is ground and polished by rotating a grinding machine. It is required that the grinding and polishing are thorough and there are no missed areas. Then, it is blown thoroughly to obtain the leather layer unit. (III) Preparation of high-strength composite panels: a3. Welding: The leather layer unit obtained in step (II) is welded with a lifting plate. The lifting plates are symmetrically welded at the four corners, for a total of 4 sets. Then the bonding surface of the leather layer unit and the bonding surface of the core unit are cleaned again. After cleaning, the furnace welding is carried out. After welding, the lifting plate is removed. Then the welding slag is cleaned, the ingot is turned over, and then it is ground and polished again. After the treatment, the welded ingot is obtained. b3. Preheating: The welded ingot obtained in step a3 is bound together with two aluminum wires at each end for secondary protection against cracking, and then preheated. The preheating process is as follows: the furnace gas temperature is set to 540°C to start heating, the metal temperature reaches 480-520°C, the furnace gas temperature drops to 520°C to start holding the temperature for 2-4 hours, and then the metal is taken out of the furnace at a temperature of 480-520°C. c3. Composite hot rolling: The welded ingot obtained in step b3 is hot rolled 32 times to obtain an 8.0mm hot composite billet coil, which is then naturally cooled. d3. Cold rolling: The hot composite billet obtained in step c3 is cooled to room temperature and then cold rolled. After 5 passes of cold rolling, a cold rolled finished coil with a thickness of 0.8 to 1.2 mm is obtained and cooled after being removed from the machine. e3. Cleaning: The cold-rolled finished coil obtained in step d3 is subjected to tension straightening and cleaning treatment. The cleaning water temperature is 50℃. Linear speed is 70–85 m / min, elongation is 0–0.3%; f3, O-state annealing: The coil obtained after cleaning in step e3 is subjected to O-state annealing. The annealing regime is as follows: the furnace gas temperature is set to 460℃ to start heating, the metal temperature reaches 330~350℃, the furnace gas temperature drops to 355℃ to start holding, and the holding time is 3~4h. After holding, the coil is taken out of the furnace. g3. Slitting and cross-cutting: Cool the roll material obtained after O-state annealing to below 40°C and then perform slitting and cross-cutting. h3. Packaging: The boards obtained after cross-cutting are stacked and packaged to obtain high-strength composite boards.

2. The preparation method of the high-strength composite sheet for new energy automobile battery liquid cooling plates according to claim 1, characterized in that: In step (1), during the smelting process, the mass percentage of the added process waste is ≤40%; the process waste is the inner-transfer edge trimming waste and head and tail material of 3003 alloy, and the alloy element composition of the process waste is Si 0~0.6%, Fe 0~0.7%, Cu 0.05~0.2%, Mn 1.0~1.5%, Mg 0~0.05%, Cr 0~0.05%, Zn 0~0.1%, Ti 0~0.05%, with the balance being Al and unavoidable impurities.

3. The preparation method of the high-strength composite sheet for new energy vehicle battery liquid cooling plates according to claim 1, characterized in that: In step (1) of the casting process, the specifications of the filter plates in the primary plate filter and the secondary plate filter are 40ppi and 50ppi, respectively; the hydrogen content in the aluminum alloy liquid obtained after filtration is <0.15ml / 100g (Al); the temperature of the settling furnace before casting is 715±5℃; the temperature of the aluminum liquid in the degassing box is 690±5℃; the online grain refiner is AL-5Ti-1B titanium wire; the stable casting speed is 46mm / min; after casting, the ingot is lifted after water cooling for 30-40 minutes.

4. The preparation method of the high-strength composite sheet for new energy vehicle battery liquid cooling plates according to claim 1, characterized in that: In step (ii), during the smelting process, the mass percentage of the added process waste is ≤40%; the process waste is the inner-transfer edge trimming waste and head and tail material of 4343 alloy, and the alloy element composition of the process waste is Si 6.8~8.2%, Fe 0~0.8%, Cu 0~0.25%, Mn 0~0.1%, Mg 0~0.05%, Cr 0~0.05%, Zn 0~0.2%, Ti 0~0.05%, with the balance being Al and unavoidable impurities.

5. The method for preparing high-strength composite material for liquid cooling plates of new energy vehicle batteries according to claim 1, characterized in that: In step (ii), during the casting process, the filter plates in the primary and secondary plate filters are both 40 ppi; the hydrogen content in the aluminum alloy liquid obtained after filtration is <0.15 ml / 100 g (Al); the temperature of the settling furnace before casting is 690-705℃; the temperature of the aluminum liquid in the degassing box is 680±5℃; the online grain refiner is AL-5Ti-0.2B titanium wire; the stable casting speed is 35 mm / min; and the ingot is lifted after water cooling for 30-40 minutes after casting is completed.

6. The method for preparing high-strength composite material for liquid cooling plates of new energy vehicle batteries according to claim 1, characterized in that: In step (3) during the welding process, the surface of the leather layer unit is 40mm narrower than that of the core layer unit, with a 20mm allowance on each side; the length of the leather layer unit is 200mm shorter than that of the core layer unit, with a 100mm allowance on each side; the polished surfaces of the leather layer unit and the core layer unit are aligned and the structural dimensions correspond. The leather layer unit is bonded to the core layer unit. After bonding, the edges along the length direction are intermittently welded, with each segment being 200mm. In the width direction, the two ends are welded respectively within a range of 200mm, and the remaining middle parts are not welded.

7. The method for preparing high-strength composite material for liquid cooling plates of new energy vehicle batteries according to claim 1, characterized in that, In step (iii) of the composite hot rolling process: During the first to fifth passes of hot rolling, the emulsion is not opened, and the rolling force is controlled according to the setting of 100 tons. The reduction per pass is ≤1mm and the rolling speed is ≤0.5m / s. In the first pass, the roll gap is opened to 550mm. The middle part of the ingot is transported to the middle of the work roll gap, and the roll gap is slowly pressed down. When the rolling force reaches no more than 100 tons, the roll gap is stopped, and the rolling is slowly rolled from the middle to one end at a speed ≤0.2mm / s. For the second to fifth passes: according to the first roll gap... The rolling process is as follows: For passes 6-8, the rolling force is controlled, with a reduction of ≤10mm and a rolling speed of ≤0.3m / s, and a roll gap is formed in each pass. For passes 9-30, the emulsion is opened, and the rolling is carried out according to the conventional process for 3003 alloy, resulting in an intermediate plate with a thickness of 24-25mm. For passes 31-32, the resulting intermediate plate is rolled in two passes with a thickness distribution of 24-25mm - 13mm - 8.0mm, an emulsion pressure of 0.3±0.05Mpa, and a final rolling temperature of 315-330℃, finally yielding an 8.0mm hot-rolled composite billet coil, which is then naturally cooled.

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