Aluminum alloy for water-cooling plate of power battery and preparation method and application of aluminum alloy

Abstract

The invention belongs to the technical field of aluminum alloy manufacturing, and particularly relates to an aluminum alloy for a power battery water cooling plate and a preparation method and application. On the basis of existing 3-series and 6-series aluminum alloys, by optimizing alloy components, the high-strength corrosion-resistant aluminum alloy for the water-cooling plate is provided, the solidus of the high-strength corrosion-resistant aluminum alloy is larger than 610 DEG C, the tensile strength after brazing aging is larger than 200 MPa, the yield strength is larger than 100 MPa, and the 720-hour neutral salt spray corrosion depth is smaller than 10%; specifically, the precipitation strengthening effect can be achieved by adding a proper amount of Mg and Si elements, the solidus of the material can be improved by adding a proper amount of Mn, Fe and Cr elements, pitting corrosion is reduced by adding a proper amount of Cr and Ti elements, uniform corrosion is promoted, and the solution strengthening effect can be achieved by adding a proper amount of Cu and Zn elements.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of aluminum alloy manufacturing, and particularly relates to an aluminum alloy for a power battery water cooling plate and a preparation method and application thereof. BACKGROUND

[0002] With the development of new energy automobile power batteries towards high energy density and fast charging, the performance of the power battery water cooling plate as a core component of the thermal management system directly affects the safety and service life of the battery pack. The component needs to meet the structural strength to withstand the mechanical load of the bottom of the large-size battery pack and the long-term corrosion resistance to avoid the risk of cooling liquid leakage, so the comprehensive performance of the aluminum alloy material used puts forward strict requirements.

[0003] At present, the power battery water cooling plate mainly uses 3003 series aluminum alloy, which has good formability and brazing performance, but has low inherent strength and is difficult to meet the load demand of large-size battery packs; at the same time, it is prone to pitting perforation during long-term service, resulting in cooling liquid leakage. In order to improve the performance, the prior art modifies the 3003 series aluminum alloy by adding Cu, Mn, Mg and other elements, but the strength improvement is limited and the corrosion resistance is further deteriorated; another scheme attempts to use 6 series aluminum alloy, but its melting point is relatively low (solidus temperature is less than 610 DEG C), which is prone to overburning deformation during brazing, and cannot meet the subsequent processing and use performance requirements.

[0004] In summary, the traditional aluminum alloy material has a fundamental contradiction between insufficient structural strength and high risk of corrosion failure in the application of the water cooling plate: the existing 3 series modified aluminum alloy is limited by the bottleneck of strength improvement and corrosion resistance defects, and the 6 series aluminum alloy is difficult to adapt to the brazing process due to the problem of melting point, and both cannot meet the strict requirements of high safety and long service life of the power battery. Therefore, developing an aluminum alloy material with high strength, high corrosion resistance and excellent brazing performance has become the key to solving the reliability and service life problems of the current water cooling plate. SUMMARY

[0005] Based on this, the application optimizes the composition and proportion of each alloy based on 3 series aluminum alloy and 6 series aluminum alloy, and obtains an aluminum alloy with excellent mechanical properties, corrosion resistance and brazing performance, which is suitable for power battery water cooling plates.

[0006] In order to achieve the above purpose, the following technical scheme can be used: The application provides an aluminum alloy for a power battery water cooling plate.

[0007] Preferably, the aluminum alloy for the power battery water cooling plate contains, The mass ratio of Mg to Si is (0.8-1.7):1; and / or The mass ratio of Mn to Fe is (0.8-2.0):1.

[0008] More preferably, the aluminum alloy for the power battery water cooling plate is selected from any one of the following: (a) Si 0.65wt%, Mg 0.80wt%, Cu 0.30wt%, Fe 0.40wt%, Mn 0.80wt%, Cr 0.50wt%, Ti 0.15wt%, Zn 0.20wt%, and the balance being Al and inevitable impurities; (b) Si 0.80wt%, Mg 0.70wt%, Cu 0.15wt%, Fe 0.30wt%, Mn 0.60wt%, Cr 0.60wt%, Ti 0.10wt%, Zn 0.10wt%, and the balance being Al and inevitable impurities; (c) Si 0.79wt%, Mg 0.89wt%, Cu 0.16wt%, Fe 0.31wt%, Mn 0.59wt%, Cr 0.59wt%, Ti 0.11wt%, Zn 0.09wt%, and the balance being Al and inevitable impurities; (d) Si 0.41wt%, Mg 0.31wt%, Cu 0.16wt%, Fe 0.29wt%, Mn 0.61wt%, Cr 0.59wt%, Ti 0.09wt%, Zn 0.11wt%, and the balance being Al and inevitable impurities; (e) Si 0.79wt%, Mg 0.32wt%, Cu 0.15wt%, Fe 0.31wt%, Mn 0.62wt%, Cr 0.60wt%, Ti 0.11wt%, Zn 0.09wt%, and the balance being Al and inevitable impurities; (f) Si 0.66wt%, Mg 0.51wt%, Cu 0.14wt%, Fe 0.50wt%, Mn 0.50wt%, Cr 0.60wt%, Ti 0.11wt%, Zn 0.11wt%, the balance being Al and inevitable impurities; (g) Si 0.67wt%, Mg 0.52wt%, Cu 0.15wt%, Fe 0.35wt%, Mn 0.50wt%, Cr 0.60wt%, Ti 0.10wt%, Zn 0.10wt%, the balance being Al and inevitable impurities.

[0009] In still another aspect, the present application provides an aluminum alloy plate for a power battery water cooling plate, which is prepared from the above-mentioned aluminum alloy for a power battery water cooling plate.

[0010] In still another aspect, the present application provides a preparation method of the above-mentioned aluminum alloy plate for a power battery water cooling plate, which comprises: (1) an aluminum alloy raw material is proportioned by mass fraction, and then sequentially subjected to melting, refining and casting to obtain an ingot; (2) the ingot is sequentially subjected to sawing and milling surface treatment and homogenization treatment to obtain a pretreated plate; (3) the pretreated plate is sequentially subjected to hot rolling, cold rolling and annealing to obtain the aluminum alloy plate for a power battery water cooling plate.

[0011] Preferably, the above-mentioned preparation method satisfies one or more of the following conditions: (i) in step (1), the temperature for melting is 700-740°C, and / or the casting speed for melting is 50-70 mm / min; (ii) in step (2), the temperature for homogenization treatment is 530-580°C, and / or the time for homogenization treatment is 12-24 h; (iii) in step (3), the opening rolling temperature for hot rolling is 420-480°C, and / or the thickness after hot rolling is 4-10 mm; (iv) in step (3), the thickness after cold rolling is 0.5-2.5 mm; (v) in step (3), the annealing comprises: holding at 280-340°C for 1-3 h, and then air cooling.

[0012] In still another aspect, the present application provides a power battery water cooling plate, which is prepared from the above-mentioned aluminum alloy for a power battery water cooling plate or the above-mentioned aluminum alloy plate for a power battery water cooling plate.

[0013] In still another aspect of the present application, a preparation method of the power battery water-cooling plate is provided, and the preparation method comprises: connecting at least two power battery water-cooling plates by brazing to obtain the power battery water-cooling plate.

[0014] Preferably, in the preparation method of the power battery water-cooling plate, The brazing temperature is 590-610 DEG C; and / or The brazing holding time is 3-8 min; and / or The cooling speed after brazing is 30-60 DEG C / min.

[0015] Preferably, in the preparation method of the power battery water-cooling plate, the power battery water-cooling plate is subjected to aging treatment after brazing, the aging treatment temperature is 200-250 DEG C; and / or the holding time is 15-60 min.

[0016] The present application has at least the following beneficial effects: based on the existing 3 series and 6 series aluminum alloys, the present application provides a high-strength corrosion-resistant aluminum alloy for water-cooling plate with solidus > 610 DEG C, tensile strength > 200 MPa after brazing and aging, yield strength > 100 MPa, and neutral salt spray corrosion depth < 10% in 720 h; specifically, adding appropriate amounts of Mg and Si elements can play a role in precipitation strengthening, adding appropriate amounts of Mn, Fe and Cr elements can increase the solidus of the material, adding appropriate amounts of Cr and Ti elements can reduce the occurrence of pitting and promote uniform corrosion, and adding appropriate amounts of Cu and Zn elements can play a role in solid solution strengthening. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 The cross-sectional morphology of the aluminum alloy prepared in the examples and comparative examples after 720 neutral salt spray corrosion is shown. DETAILED DESCRIPTION

[0018] The examples are provided to better illustrate the present application, but are not intended to limit the present application to only the examples. Therefore, the skilled in the art can make non-essential improvements and adjustments to the embodiments according to the above description, which still belong to the protection scope of the present application.

[0019] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. Unless otherwise defined, all terms of expression whether in the specification, claims, or both reflect the terminology used by those skilled in the art and are intended to carry the same meaning as commonly understood by those skilled in the art. As used herein, it is also to be understood that the use of "comprise", "have", "contain", or "include" or variants thereof does not exclude the presence of other than the stated features, integers, actions, components, elements, materials or combinations thereof. As used herein, " / " can be interpreted as "and" or "or" depending on the context.

[0020] The conventional 3003 aluminum alloy has low strength and poor corrosion resistance, the existing modified 3003 aluminum alloy has limited strength improvement and poor corrosion resistance, and the 6-series aluminum alloy has a low melting point and is easy to overburn, which greatly affects the reliability and service life of the water-cooled plate.

[0021] To solve the above problems, the present application can adopt the following technical solutions: In a first aspect, the present application provides an aluminum alloy for a power battery water-cooled plate, the aluminum alloy for the power battery water-cooled plate comprises, in terms of mass fraction: Si 0.30wt%-0.90wt%, Mg 0.40wt%-0.80wt%, Cu 0.05wt%-0.30wt%, Fe 0.10wt%-0.50wt%, Mn 0.50wt%-1.00wt%, Cr 0.20wt%-0.60wt%, Ti 0.05wt%-0.20wt%, Zn≤0.20wt%, and the balance being Al and unavoidable impurities.

[0022] It should be noted that the alloy composition is optimized, Mg and Si elements are added to play the role of precipitation strengthening, Mn, Fe and Cr elements are added to improve the solidus of the material, Cr and Ti elements reduce the occurrence of pitting and promote uniform corrosion, and appropriate addition of Cu and Zn elements can play the role of solid solution strengthening. It should be understood that the above-mentioned elements need to be added in an appropriate amount, for example, although Cr element can improve the solidus and promote the passivation film of aluminum alloy to be more uniform and reduce the occurrence of pitting, but too high content will generate brittle phase and reduce mechanical properties; although Ti element can refine the grain, promote uniform corrosion and improve corrosion resistance, but the content exceeding a certain limit will not play a role; although the addition of Cu and Zn elements can play the role of solid solution strengthening, but too high content will reduce the solidus and significantly reduce the corrosion resistance of the material. The solidus of the aluminum alloy obtained by the present application under the above-mentioned alloy composition is > 610 DEG C, the tensile strength after brazing aging is > 200 MPa, the yield strength is > 100 MPa, and the neutral salt spray corrosion depth is < 10% in 720 h, which indicates that the obtained aluminum alloy has excellent mechanical properties and strong corrosion resistance.

[0023] In some specific examples, in the above-mentioned aluminum alloy for power battery water cooling plate, The mass ratio of Mg and Si is (0.8-1.7): 1; and / or The mass ratio of Mn and Fe is (0.8-2.0): 1.

[0024] It should be noted that, as described above, the addition of Mg and Si elements can precipitate Mg2Si aging strengthening phase, but the content and mass ratio of Mg and Si should be controlled within a reasonable range, too high content and too low mass ratio will lead to grain boundary segregation and reduce corrosion resistance and plasticity, too low content and too high mass ratio will weaken the effect of aging strengthening; the mass ratio of Mg and Si in the present application can be preferably (0.8-1.7):1, for example 1:1, 1.2:1, 1.4:1 or 1.5:1, etc., the mechanical properties and corrosion resistance of the aluminum alloy obtained under this ratio are better than those of other ratios. In addition, as described above, the addition of Fe and Mn elements can increase the solidus and play a role in solid solution strengthening, but the content and mass ratio of Mn and Fe should be controlled within a reasonable range, too low solidus will lead to overburning of the material, too high content will lead to coarsening of iron-rich phase and reduce the mechanical properties, the mass ratio of Mn and Fe in the present application can be preferably (0.8-2.0):1, for example 0.9:1, 1:1, 1.1:1, 1.5:1, 1.9:1, etc., the mechanical properties and corrosion resistance of the aluminum alloy obtained under this ratio are better than those of other ratios. It should be understood that the present application more preferably satisfies the above range for the mass ratio of Mg and Si and the mass ratio of Mn and Fe at the same time, and the mechanical properties and corrosion resistance of the aluminum alloy obtained by simultaneously satisfying the above range are more excellent.

[0025] In some specific examples, the above-mentioned aluminum alloy for power battery water-cooling plate is selected from any one of the following: (a) Si 0.65wt%, Mg 0.80wt%, Cu 0.30wt%, Fe 0.40wt%, Mn 0.80wt%, Cr 0.50wt%, Ti 0.15wt%, Zn 0.20wt%, the balance being Al and unavoidable impurities; (b) Si 0.80wt%, Mg 0.70wt%, Cu 0.15wt%, Fe 0.30wt%, Mn 0.60wt%, Cr 0.60wt%, Ti 0.10wt%, Zn 0.10wt%, the balance being Al and unavoidable impurities; (c) Si 0.79wt%, Mg 0.89wt%, Cu 0.16wt%, Fe 0.31wt%, Mn 0.59wt%, Cr 0.59wt%, Ti 0.11wt%, Zn 0.09wt%, the balance being Al and unavoidable impurities; (d) Si 0.41wt%, Mg 0.31wt%, Cu 0.16wt%, Fe 0.29wt%, Mn 0.61wt%, Cr 0.59wt%, Ti 0.09wt%, Zn 0.11wt%, the balance being Al and unavoidable impurities; (e) Si 0.79wt%, Mg 0.32wt%, Cu 0.15wt%, Fe 0.31wt%, Mn 0.62wt%, Cr 0.60wt%, Ti 0.11wt%, Zn 0.09wt%, the balance being Al and inevitable impurities; (f) Si 0.66wt%, Mg 0.51wt%, Cu 0.14wt%, Fe 0.50wt%, Mn 0.50wt%, Cr 0.60wt%, Ti 0.11wt%, Zn 0.11wt%, the balance being Al and inevitable impurities; (g) Si 0.67wt%, Mg 0.52wt%, Cu 0.15wt%, Fe 0.35wt%, Mn 0.50wt%, Cr 0.60wt%, Ti 0.10wt%, Zn 0.10wt%, the balance being Al and inevitable impurities.

[0026] It should be noted that the above-mentioned power battery water-cooled plate aluminum alloy has excellent mechanical properties and corrosion resistance, and the power battery water-cooled plate aluminum alloy in the present application can preferably be the above-mentioned aluminum alloy.

[0027] In a second aspect, the present application provides a power battery water-cooled plate aluminum alloy plate prepared from the above-mentioned power battery water-cooled plate aluminum alloy.

[0028] It should be noted that the aluminum alloy in the present application has excellent mechanical properties and corrosion resistance, and can be prepared into a power battery water-cooled plate aluminum alloy plate. It should be understood that the preparation method and form of the power battery water-cooled plate aluminum alloy plate are well known in the art.

[0029] In a third aspect, the present application provides a preparation method of the above-mentioned power battery water-cooled plate aluminum alloy plate, which comprises: (1) The aluminum alloy raw materials are proportioned according to the mass fraction, and then sequentially subjected to melting, refining and casting to obtain an ingot; (2) The ingot is sequentially subjected to sawing and milling surface treatment and homogenization treatment to obtain a pretreated plate; (3) The pretreated plate is sequentially subjected to hot rolling, cold rolling and annealing to obtain a power battery water-cooled plate aluminum alloy plate.

[0030] It should be noted that the preparation method of the power battery water-cooled plate aluminum alloy plate in the present application can preferably be the above-mentioned method, and the terms "melting", "refining", "casting", "sawing and milling surface", "homogenization", "hot rolling", "cold rolling" and "annealing" are all professional terms in the art and have no specific meaning.

[0031] In some specific examples, the above preparation method satisfies one or more of the following conditions: (i) in step (1), the temperature of the melting is 700-740℃, and / or the casting speed of the melting is 50-70mm / min; specifically, the temperature of the melting can be 700-740℃, such as 710℃, 720℃ or 730℃, etc.; the casting speed of the melting can be 50-70mm / min, such as 55mm / min, 60mm / min or 65mm / min, etc. (ii) in step (2), the temperature of the homogenization treatment is 530-580℃, and / or the time of the homogenization treatment is 12-24h; specifically, the temperature of the homogenization treatment can be 530-580℃, such as 540℃, 550℃, 560℃ or 570℃, etc.; the time of the homogenization treatment can be 12-24h, such as 15h, 17h, 20h or 23h, etc. (iii) in step (3), the open rolling temperature of the hot rolling is 420-480℃, and / or the thickness after the hot rolling is 4-10mm; specifically, the open rolling temperature of the hot rolling can be 420-480℃, such as 430℃, 440℃, 450℃, 460℃ or 470℃, etc.; the thickness after the hot rolling can be 4-10mm, such as 5mm, 6mm, 7mm, 8mm or 9mm, etc. (iv) in step (3), the thickness after the cold rolling is 0.5-2.5mm; specifically, the thickness after the cold rolling can be 0.5-2.5mm, such as 1mm, 1.5mm or 2mm, etc. (v) in step (3), the annealing comprises: holding at 280-340℃ for 1-3h, and then air cooling; specifically, the temperature of the annealing can be 280-340℃, such as 290℃, 300℃, 310℃, 320℃ or 330℃, etc., and the holding time can be 1-3h, such as 1.5h, 2h or 2.5h, etc.

[0032] In a fourth aspect, an embodiment of the present application provides a power battery water cooling plate prepared from the above-mentioned aluminum alloy for power battery water cooling plate or the above-mentioned aluminum alloy plate for power battery water cooling plate.

[0033] It should be noted that, based on the excellent mechanical properties and corrosion resistance of the aluminum alloy in the present application, the power battery water cooling plate prepared therefrom can be prepared into a power battery water cooling plate. The specifications and preparation methods of the power battery water cooling plate are known in the art.

[0034] In a fifth aspect, an embodiment of the present application provides a preparation method of the above-mentioned power battery water cooling plate, which comprises: connecting at least two pieces of the aluminum alloy plate for power battery water cooling plate through brazing to obtain the power battery water cooling plate.

[0035] It should be noted that the specifications and models of the power battery water cooling plate in the present application are known in the art, for example, a groove can be formed on an aluminum alloy plate, and then an aluminum alloy plate without a groove is connected by brazing to obtain a power battery water cooling plate; in addition, aluminum alloy plates with grooves are connected by brazing to obtain a power battery water cooling plate (the grooves are correspondingly arranged).

[0036] In some specific examples, in the preparation method of the power battery water cooling plate, The brazing temperature is 590-610°C (such as 595°C, 600°C or 605°C, etc.); and / or The brazing holding time is 3-8 min (such as 4 min, 5 min, 6 min or 7 min, etc.); and / or The cooling speed after brazing is 30-60°C / min (such as 35°C / min, 40°C / min, 45°C / min, 50°C / min or 55°C / min, etc.).

[0037] It should be noted that if the brazing temperature is too low or the time is too short, the water cooling plate cannot be effectively connected, and if the brazing temperature is too high or the time is too long, the material will be overburned, affecting the final performance; if the brazing cooling speed is too low, the aging phase will be precipitated early, the aging strengthening effect will be weak, and if the cooling speed is too fast, the material will be deformed and cannot meet the use requirements; in the present application, the brazing temperature, brazing holding time and cooling speed are preferably listed above. In addition, it should be understood that the cooling method is known in the art, for example, water cooling, air cooling or fog cooling.

[0038] In some specific examples, in the preparation method of the power battery water cooling plate, the power battery water cooling plate is subjected to aging treatment after brazing, the aging treatment temperature is 200-250°C; and / or the holding time is 15-60 min.

[0039] It should be noted that the aging process is also an important factor affecting the performance of the water cooling plate, and if the aging temperature is too low and the time is too short, the aging phase cannot be fully precipitated, and the material strength is low; if the aging temperature is too high and the time is too long, the material organization will be coarsened and the energy efficiency will be too high, thereby affecting the performance of the water cooling plate and the production cost. In the present application, the aging treatment temperature is preferably 200-250°C, such as 210°C, 220°C, 230°C or 240°C, etc., and the holding time is preferably 15-60 min, such as 20 min, 30 min, 40 min, 50 min or 55 min, etc.

[0040] In order to better understand the present application, the content of the present application will be further illustrated below in combination with specific examples, but the content of the present application is not limited to the following examples.

[0041] Preparation Example Example 1 (1) Melting: The alloy components in Table 1 below were weighed and placed in a melting furnace to obtain molten aluminum; the melting temperature was 720°C, and the casting speed was 70 mm / min; (2) Casting: The molten aluminum was transferred to a converter, then refined for 30 min under Ar gas at 720°C, then cast after standing for 30 min. The core material was sawed and milled after casting. The ingot was sawed to remove a 50 mm region from the head and tail, respectively, and then milled to a depth of 5 mm on each side. The ingot was then subjected to homogenization treatment at a temperature of 560°C for 18 h; (3) Hot rolling: The homogenized ingot was hot-rolled at an initial rolling temperature of 460°C, and then hot-rolled in multiple passes to a final thickness of 6 mm; (4) Cold rolling: The hot-rolled sheet was cold-rolled in multiple passes to a final product thickness of 1.2 mm; (5) Product annealing: The cold-rolled sheet was annealed at 300°C for 1.5 h, and then naturally cooled in air; (6) Brazing: The annealed sheet was processed to form a groove, and then two power battery water-cooled plates were gas shielded brazed using the aluminum alloy sheet as the brazing material. The protective gas was nitrogen, and the brazing material was 4045 aluminum alloy (the specific components of the 4045 aluminum alloy were Si 9wt%-11wt%, Mg≤0.05wt%, Cu≤0.3wt%, Fe≤0.8wt%, Mn≤0.05wt%, Ti≤0.2wt%, Zn≤0.1wt%, and the balance was Al and unavoidable impurities). The brazing material was subjected to combined hot rolling with one of the plates. The brazing temperature was 600°C, the holding time was 5 min, and the cooling rate was 30°C / min; (7) Artificial aging: The brazed sheet was subjected to artificial aging at a temperature of 240°C for 30 min.

[0042] Table 1 Alloy components in Example 1

[0043] Example 2 (1) Melting: The alloy components in Table 2 below were weighed and placed in a melting furnace to obtain molten aluminum, and the melting temperature was 730°C and the casting speed was 50 mm / min; (2) Casting: The molten aluminum is refined in a converter, then refined in Ar gas at 720℃ for 30min, then cast after standing for 30min, and then the core material is sawed and milled to process, and the ingot is sawed to remove a 50mm region at the head and tail respectively, and then each face is milled by 5mm, and then homogenization treatment is performed, the homogenization treatment temperature is 580℃, and the time is 12h; (3) Hot rolling: The homogenization treatment is hot rolled, the opening rolling temperature is 480℃, and after multi-pass hot rolling, it is finally rolled to 8mm; (4) Cold rolling: The hot-rolled plate is cold-rolled in multiple passes, and the final product thickness is 1.0mm; (5) Product annealing: The cold-rolled plate is annealed at 280℃ for 3h, and then naturally cooled in air; (6) Brazing: The plate after product annealing is processed to form a groove, and then two power battery water-cooled plates are gas shielded brazed with aluminum alloy plates, the shielding gas is nitrogen, the brazing material is 4045 aluminum alloy (the specific composition of 4045 aluminum alloy is Si 9wt%-11wt%, Mg≤0.05wt%, Cu≤0.3wt%, Fe≤0.8wt%, Mn≤0.05wt%, Ti≤0.2wt%, Zn≤0.1wt%, and the balance is Al and unavoidable impurities), and the brazing material needs to be subjected to combined hot rolling with one of the plates; the brazing temperature is 600℃, the holding time is 5min, and the cooling rate is 60℃ / min; (7) Artificial aging: The brazed plate is subjected to artificial aging treatment, the aging temperature is 200℃, and the holding time is 60min.

[0044] Table 2 Alloy composition in Example 2

[0045] Example 3 Example 3 is substantially the same as Example 2, except that the mass percentage of the alloy composition in step (1) is different (especially Mg and Si), and the others are the same as Example 2; wherein in Example 3, the mass percentage of the alloy composition in step (1) is shown in Table 3 below.

[0046] Table 3 Alloy composition in Example 3

[0047] Example 4 Example 4 is substantially the same as Example 2, except that the mass percentage of the alloy composition in step (1) is different (especially Mg and Si), and the others are the same as Example 2; wherein in Example 4, the mass percentage of the alloy composition in step (1) is shown in Table 4 below.

[0048] Table 4 Alloy composition in Example 4

[0049] Example 5 Example 5 is substantially the same as Example 2, except that the mass percentage of the alloying components in step (1) is different (especially Mg and Si), and the rest is the same as Example 2; wherein in Example 5, the mass percentage of the alloying components in step (1) is shown in Table 5 below.

[0050] Table 5 Alloy composition in Example 5

[0051] Example 6 Example 6 is substantially the same as Example 2, except that the mass percentage of the alloying components in step (1) is different (especially Mg, Si, Fe and Mn), and the rest is the same as Example 2; wherein in Example 6, the mass percentage of the alloying components in step (1) is shown in Table 6 below.

[0052] Table 6 Alloy composition in Example 6

[0053] Example 7 Example 7 is substantially the same as Example 2, except that the mass percentage of the alloying components in step (1) is different (especially Mg, Si, Fe and Mn), and the rest is the same as Example 2; wherein in Example 7, the mass percentage of the alloying components in step (1) is shown in Table 7 below.

[0054] Table 7 Alloy composition in Example 7

[0055] Example 8 Example 8 is substantially the same as Example 2, except that the brazing temperature in step (6) is different, and the rest is the same as Example 2; wherein in Example 8, the brazing temperature in step (6) is 580℃.

[0056] Example 9 Example 9 is substantially the same as Example 2, except that the brazing temperature in step (6) is different, and the rest is the same as Example 2; wherein in Example 9, the brazing temperature in step (6) is 620℃.

[0057] Example 10 Example 10 is substantially the same as Example 2, except that the aging temperature in step (7) is different, and the rest is the same as Example 2; wherein in Example 10, the aging temperature in step (7) is 180℃.

[0058] Example 11 Example 11 is substantially the same as Example 2, except that the aging temperature in step (7) is different, and the others are the same as Example 2; wherein the brazing temperature in step (7) in Example 11 is 270℃.

[0059] Comparative Example 1 Comparative Example 1 is substantially the same as Example 1, except that the mass percentage of alloying components in step (1) is different, and the others are the same as Example 1; wherein in Comparative Example 1, the mass percentage of alloying components in step (1) is shown in Table 8 (i.e. 3003 alloying components).

[0060] Table 8 Alloying components in Comparative Example 1

[0061] Comparative Example 2 Comparative Example 2 is substantially the same as Example 1, except that the mass percentage of alloying components in step (1) is different, and the others are the same as Example 1; wherein in Comparative Example 2, the mass percentage of alloying components in step (1) is shown in Table 9 (i.e. 6A02 aluminum alloying components).

[0062] Table 9 Alloying components in Comparative Example 2

[0063] Comparative Example 3 Comparative Example 3 is substantially the same as Example 1, except that the mass percentage of alloying components in step (1) is different, and the others are the same as Example 1; wherein in Comparative Example 3, the mass percentage of alloying components in step (1) is shown in Table 10.

[0064] Table 10 Alloying components in Comparative Example 3

[0065] Comparative Example 4 Comparative Example 4 is substantially the same as Example 1, except that the mass percentage of alloying components in step (1) is different, and the others are the same as Example 1; wherein in Comparative Example 4, the mass percentage of alloying components in step (1) is shown in Table 11.

[0066] Table 11 Alloying components in Comparative Example 4

[0067] Comparative Example 5 Comparative Example 5 is substantially the same as Example 2, except that the mass percentage of alloying components in step (1) is different, and the others are the same as Example 2; wherein in Comparative Example 5, the mass percentage of alloying components in step (1) is shown in Table 12.

[0068] Table 12 Alloy composition in Comparative Example 5

[0069] Comparative Example 6 Comparative Example 6 is substantially the same as Example 2, except that the mass percentage of the alloy composition in step (1) is different, and the others are the same as Example 2; wherein in Comparative Example 6, the mass percentage of the alloy composition in step (1) is shown in Table 13 below.

[0070] Table 13 Alloy composition in Comparative Example 6

[0071] Comparative Example 7 Comparative Example 7 is substantially the same as Example 2, except that the mass percentage of the alloy composition in step (1) is different, and the others are the same as Example; wherein in Comparative Example 7, the mass percentage of the alloy composition in step (1) is shown in Table 14 below.

[0072] Table 14 Alloy composition in Comparative Example 7

[0073] Comparative Example 8 Comparative Example 8 is substantially the same as Example 2, except that the mass percentage of the alloy composition in step (1) is different, and the others are the same as Example; wherein in Comparative Example 8, the mass percentage of the alloy composition in step (1) is shown in Table 15 below.

[0074] Table 15 Alloy composition in Comparative Example 8

[0075] Performance test (1) Solidus and mechanical property test Solidus: According to GB / T 1425-2021, the solidus of the power battery water-cooled plates prepared in each example and each comparative example was detected, and the detection results are shown in Table 16; Yield strength: According to GB / T 228.1-2021 Part 1: Room temperature test method, the yield strength of the power battery water-cooled plates prepared in each example and each comparative example was detected, and the detection results are shown in Table 16; Tensile strength: According to GB / T 228.1-2021 Part 1: Room temperature test method, the tensile strength of the power battery water-cooled plates prepared in each example and each comparative example was detected, and the detection results are shown in Table 16; Elongation: According to GB / T 228.1-2021 Part 1: Room temperature test method, the elongation of the power battery water-cooled plates prepared in each example and each comparative example was detected, and the detection results are shown in Table 16.

[0076] Table 16 Performance test results of water-cooled plates prepared from examples and comparative examples

[0077] From the above Table 16, it can be seen that the tensile strength of the aluminum alloy prepared in Examples 1 to 11 is above 200 MPa, the yield strength is above 100 MPa, and the elongation is above 10%, which is significantly higher than that of Comparative Examples 1 to 8. Among them, the solidus of Examples 1 and 2 is above 610℃, and the tensile strength is above 200 MPa and the yield strength is above 100 MPa. Comparative Example 1 is a commonly used 3003 alloy for water-cooled plates, which has a high solidus but low strength. Comparative Example 2 is a 6A02 aluminum alloy, which has obvious precipitation strengthening effect, but the solidus is too low, causing local melting and overburning during brazing, resulting in coarse structure and failure of age hardening to play a role, resulting in low material strength. Although the solidus of Comparative Example 3 meets the requirements, the Mg and Si elements are too low to precipitate enough age hardening phases, resulting in low material strength. The solidus of Comparative Example 5 is too low, causing overburning during brazing, resulting in low material strength. The brazing cooling speed of Comparative Example 7 is too slow, and the aging temperature is too low, which cannot precipitate strengthening phases, resulting in low material strength. In addition, by comparing Comparative Example 1 with Comparative Examples 3 and 4, it can be seen that when the content of Mg and Si exceeds the range of Si 0.3wt%-0.9wt% and Mg 0.4wt%-0.8wt%, the mechanical properties decrease significantly. By comparing Comparative Example 2 with Comparative Examples 5 and 6, it can be seen that when the content of Fe and Mn exceeds the range of Fe 0.1wt%-0.5wt% and Mn 0.5wt%-1.0wt%, the mechanical properties decrease significantly. By comparing Comparative Example 2 with Comparative Examples 7 and 8, it can be seen that when the content of Ti and Cr exceeds the range of Ti 0.05wt%-0.2wt% and Cr 0.2wt%-0.6wt%, the mechanical properties decrease significantly.

[0078] (2) Corrosion resistance test The water-cooled plates prepared from examples and comparative examples were subjected to 720h neutral salt spray corrosion test, the reagent was 5% NaCl solution, and the pH value was 6.5-7.2. After the corrosion test, the maximum corrosion depth was tested, and the results are shown in Table 17.

[0079] Table 17 Results of 720h neutral salt spray corrosion test of examples and comparative examples

[0080] From the above Table 17, it can be seen that: Example 1 and Example 2 both show excellent corrosion resistance under 720h neutral salt spray corrosion, and the corrosion depth is less than 10%; Comparative Example 1 and Comparative Example 2 have low Cr and Ti elements, and poor corrosion resistance; Comparative Example 3, Comparative Example 4, Comparative Example 6 and Comparative Example 8 have high Cr and Ti elements, and good corrosion resistance, but low strength; Comparative Example 5 and Comparative Example 7 both have low Cr and Ti elements, and further decreased corrosion resistance; In addition, the corrosion cross-section morphology is observed by a metallographic microscope, and the cross-section corrosion morphology of Example 1 and Example 2 and Comparative Example 3, Comparative Example 5 and Comparative Example 7 is shown in FIG. 1. Figure 1 As can be seen from the figure, the alloy composition range of Example 1 and Example 2 is in the target range, and has excellent corrosion resistance; although Comparative Example 3 has good corrosion resistance, it has low strength; Comparative Example 5 and 7 have alloy composition not in the target range, and have low Ti and Cr elements, and have obvious corrosion phenomenon, and have poor corrosion resistance, which is consistent with the above maximum corrosion depth.

[0081] Finally, it should be pointed out that the above examples are only used to illustrate the technical solutions of the present application, not to limit it. Although the present application has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that the technical solutions of the present application can be modified or replaced by equivalents without departing from the purpose and scope of the present application, and they should be covered in the scope of the claims of the present application.

Claims

1. An aluminum alloy for a power battery water cooling plate, characterized by, The aluminum alloy for a power battery water cooling plate comprises, in terms of mass fraction, Si 0.30wt%-0.90wt%, Mg 0.40wt%-0.80wt%, Cu 0.05wt%-0.30wt%, Fe 0.10wt%-0.50wt%, Mn 0.50wt%-1.00wt%, Cr 0.20wt%-0.60wt%, Ti 0.05wt%-0.20wt%, Zn≤0.20wt%, and the balance of Al and inevitable impurities.

2. The aluminum alloy for a power battery water cooling plate according to claim 1, characterized in that, the mass ratio of Mg and Si is (0.8-1.7):1; and / or the mass ratio of Mn and Fe is (0.8-2.0):

1.

3. The aluminum alloy for a power battery water cooling plate according to claim 1, characterized in that, The aluminum alloy for a power battery water cooling plate is selected from any one of the following: (a) Si 0.65wt%, Mg 0.80wt%, Cu 0.30wt%, Fe 0.40wt%, Mn 0.80wt%, Cr 0.50wt%, Ti 0.15wt%, Zn 0.20wt%, and the balance of Al and inevitable impurities; (b) Si 0.80wt%, Mg 0.70wt%, Cu 0.15wt%, Fe 0.30wt%, Mn 0.60wt%, Cr 0.60wt%, Ti 0.10wt%, Zn 0.10wt%, and the balance of Al and inevitable impurities; (c) Si 0.79wt%, Mg 0.89wt%, Cu 0.16wt%, Fe 0.31wt%, Mn 0.59wt%, Cr 0.59wt%, Ti 0.11wt%, Zn 0.09wt%, and the balance of Al and inevitable impurities; (d) Si 0.41wt%, Mg 0.31wt%, Cu 0.16wt%, Fe 0.29wt%, Mn 0.61wt%, Cr 0.59wt%, Ti 0.09wt%, Zn 0.11wt%, and the balance of Al and inevitable impurities; (e) Si 0.79wt%, Mg 0.32wt%, Cu 0.15wt%, Fe 0.31wt%, Mn 0.62wt%, Cr 0.60wt%, Ti 0.11wt%, Zn 0.09wt%, and the balance of Al and inevitable impurities; (f) Si 0.66wt%, Mg 0.51wt%, Cu 0.14wt%, Fe 0.50wt%, Mn 0.50wt%, Cr 0.60wt%, Ti 0.11wt%, Zn 0.11wt%, and the balance of Al and inevitable impurities; (g) Si 0.67wt%, Mg 0.52wt%, Cu 0.15wt%, Fe 0.35wt%, Mn 0.50wt%, Cr 0.60wt%, Ti 0.10wt%, Zn 0.10wt%, the balance being Al and inevitable impurities.

4. An aluminum alloy sheet for a power battery water-cooling plate, characterized by comprising, in mass %, The power battery water-cooled plate is made of the aluminum alloy according to any one of claims 1 to 3.

5. The method of claim 4, wherein the aluminum alloy sheet for a power battery water-cooling plate is prepared by the steps of: preparing an aluminum alloy sheet; and performing a surface treatment on the aluminum alloy sheet. The preparation method comprises: (1) the aluminum alloy raw materials are proportioned according to mass fraction, and then sequentially subjected to melting, refining and casting to obtain a cast ingot; (2) the cast ingot is sequentially subjected to sawing and milling surface treatment and homogenization treatment to obtain a pretreated plate; (3) the pretreated plate is sequentially subjected to hot rolling, cold rolling and annealing to obtain the aluminum alloy plate for the power battery water-cooled plate.

6. The production method according to claim 5, wherein The preparation method satisfies one or more of the following conditions: (i) in step (1), the temperature for melting is 700-740 DEG C, and / or the casting speed for melting is 50-70 mm / min; (ii) in step (2), the temperature for homogenization treatment is 530-580 DEG C, and / or the time for homogenization treatment is 12-24 h; (iii) in step (3), the opening rolling temperature for hot rolling is 420-480 DEG C, and / or the thickness after hot rolling is 4-10 mm; (iv) in step (3), the thickness after cold rolling is 0.5-2.5 mm; (v) in step (3), the annealing comprises: holding at 280-340 DEG C for 1-3 h, and then air cooling.

7. A power cell water-cooling plate, characterized in that, The power battery water-cooled plate is made of the aluminum alloy according to any one of claims 1 to 3 or the aluminum alloy plate for the power battery water-cooled plate according to claim 4.

8. The method of claim 7, wherein the method further comprises: forming the water channel by etching the first and second metal layers. The preparation method comprises: connecting at least two aluminum alloy plates for the power battery water-cooled plate through brazing to obtain the power battery water-cooled plate.

9. The preparation method according to claim 8, wherein, the temperature for brazing is 590-610 DEG C; and / or the holding time for brazing is 3-8 min; and / or the cooling speed after brazing is 30-60 DEG C / min.

10. The production method according to claim 8 or 9, characterized by, After brazing, the power battery water-cooled plate is subjected to aging treatment, the temperature for aging treatment is 200-250 DEG C; and / or the holding time is 15-60 min.

Images