Aluminum alloy-based heat exchangers obtained by brazing

Abstract

The present invention relates to a strip or plate intended for the manufacture of brazed heat exchangers, comprising a core layer 18, optionally a coating layer 16, 17 on one or both sides of the core layer 18, and optionally an intermediate layer on one or both sides of the core layer 18, located between the core layer 18 and the coating layer 16, 17, wherein the core layer 18 is a 6xxx series aluminum alloy having the following composition by mass percentage: Si: 0.45-0.75; Fe: 0.18-0.40%; Cu: ≦0.40%; Mn: ≦0.30%; Mg: 0.25-0.56%; Ti: <0.050%; optionally V: 0.05-0.16%; unavoidable impurities: each <0.05% and in total <0.15%; the remainder being aluminum.

Description

[Technical field]

[0001] The invention relates to thin strips or plates (typically 0.1-2.5 mm thick) made of aluminum-manganese-silicon core alloys (6xxx series according to the Aluminum Association nomenclature) clad, possibly on one or both sides, with a cladding alloy, most often an aluminum-silicon brazing alloy (4xxx series according to the Aluminum Association nomenclature) or an aluminum, aluminum-manganese or aluminum-zinc sacrificial alloy (1xxx, 3xxx or 7xxx series according to the Aluminum Association nomenclature), and / or an intermediate alloy made of aluminum or an aluminum-manganese alloy (1xxx or 3xxx series according to the Aluminum Association nomenclature), placed between the core layer and any brazing alloy. These strips or plates are intended in particular for the manufacture of elements such as plates of heat exchangers assembled by brazing, in particular for automotive applications, such as battery coolers for electric vehicles.

[0002] Brazing techniques for aluminum alloys are described, for example, in the article "Le brasage fort de l'aluminium et ses alliages" by JC Cucza, A. Uhry and JC Goussain, published in Soudage et Techniques Connexes, November-December 1991, pp. 18-29. The strip or plate according to the invention can be used in particular in brazing techniques with non-corrosive fluxes of the NOCOLOK® or CAB ("Controlled Atmosphere Brazing") type. [Background technology]

[0003] With the development of electric vehicles, the market for battery coolers is expanding. This component currently aims to control the operating temperature of the battery within a range of typically 20-100°C, preferably 30-80°C. The components can be of large dimensions (1-2 meters).

[0004] One current design example of an electric vehicle battery cooler is shown in FIG. 1. It consists of two parts, a flat part 11 and a pressed part 12, assembled in such a way as to create a channel 13 with a core layer 15 made of a 3xxx series alloy. In this specification, the term "flat part" means a part that is not pressed before assembly, whereas the term "pressed part" means a part that is pressed before assembly in such a way that the channel is created after assembly with the flat part. In operation, the channel is used for circulating the cooling fluid in the electric vehicle battery cooler. Besides the core layer 15 made of a 3xxx series alloy, a sacrificial layer 16 made of, for example, a 7xxx or 1xxx series alloy can be added to ensure SWAAT corrosion resistance on the outer surface of each of the two parts 11 and 12. The pressed part 12 also includes a brazing layer 17 made of a 4xxx series alloy on the opposite side of the core layer 15 made of a 3xxx series alloy to the sacrificial layer 16 to ensure the brazing of the two parts 11 and 12 together. The battery 14 is in contact with the flat part 11 but not with the pressed part 12 .

[0005] The properties required for the aluminium alloy strip or plate used for the manufacture of the brazed exchangers are, in particular, sufficient formability to easily form plates before brazing, good brazing properties, high mechanical strength after brazing in order to use the thinnest possible thicknesses and thus guarantee part of the strength of the overall structure of the battery box, good resistance to fatigue stresses during operation and good corrosion resistance after brazing. Naturally, it is important that the alloy selected is easy to cast and roll and that the manufacturing costs of the strip or plate are compatible with the requirements of the automotive industry.

[0006] In order to facilitate the reduction of plate thickness for heat exchangers (such as battery coolers for electric vehicles, which may also serve as structural components in some cases), it is particularly desirable to improve the mechanical properties of the material after brazing, in particular the yield strength (Rp 0.2) ("Yield Strength" or "YS" in English) is advantageous.

[0007] Solutions have been proposed in this respect. By way of example, reference may be made to the following patents and patent applications which disclose the following compositions and configurations: JP 2005-261026 discloses a core made of an alloy of the 3xxx series, particularly for use in pipes, which contains, in particular by percentage by mass: more than 0.8% Mn; 0.3-0.6% Mg; less than 0.5% Si. - EP 1254965 discloses a structurally hardened aluminium alloy having the following composition in mass percentages: 0.6-0.9% Si; 0.1-0.36% Mg; 0.4-0.7% Mn; 0.1-0.25% Ti; 0.25-0.35% Cu; less than 0.7% Fe; and optionally 0.05-0.25% Zr. - EP 1 687 456 relates to the field of fluxless brazing and discloses a core coated on at least one side with a brazing aluminium alloy containing, in percentages by mass: 4-15% Si and 0.01-0.5% of at least one of the elements Ag, Be, Bi, Ce, La, Pb, Pd, Sb, Y or misch metal, the remainder being aluminium, containing, in percentages by mass: 0.3-1.0% Si; less than 1.0% Fe; 0.3-1.0% Cu; 0.3-2.0% Mn; 0.3-3.0% Mg; less than 6% Zn; less than 0.1% Ti; less than 0.3% Zr; less than 0.3% Cr; less than 2.0% Ni; less than 2.0% Co; less than 0.5% Bi; less than 0.5% Y; less than 0.05% each and less than 0.15% in total of other elements, the remainder being aluminium. - EP 3423607 discloses a solution made of an alloy of the 6xxx series, consisting, in mass percentages, of: 0.2-1.3% Si; 0.40-1.3% Mg; not more than 0.80% Cu; 0.05-1.0% Fe; 0.05-0.70% Mn; optionally one or two elements selected from 0.05-0.35% Zr and 0.04-0.35% Cr; not more than 25% Zn; not more than 0.25% Ti; the balance being unavoidable impurities and aluminium, where the Fe / Mn ratio is less than 1.90. - WO 2021 / 204929 discloses a core made of an AA6xxx series alloy having the following composition, in mass percentages: 0.5-0.9% Si; less than 0.5% Fe; less than 0.5% Cu; less than 0.5% Mn; 0.4-0.8% Mg; less than 0.3% Cr; less than 0.3% Zn; less than 0.3% Ti; less than 0.1% Zr; the remainder being Aluminium and unavoidable impurities with a maximum of 0.05% each and a maximum of 0.15% in total.

[0008] However, the proposed solution is particularly aimed at achieving a high enough solidus temperature of the alloy of the core layer to allow melting of the brazing layer while avoiding melting of the core layer, in particular Rp 0.2 From the viewpoint of the above, however, it has not been possible to necessarily achieve a good trade-off between excellent mechanical strength after brazing, excellent corrosion resistance, and excellent brazeability. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] JP 2005-261026 A [Patent Document 2] European Patent No. 1254965 [Patent Document 3] European Patent No. 1687456 [Patent Document 4] European Patent No. 3423607 [Patent Document 5] International Publication No. 2021 / 204929 Summary of the Invention [Problem to be solved by the invention]

[0010] In the face of expanding market demand, we have developed a new product, especially Rp 0.2 In view of this, there is still a need for new core alloys with improved mechanical strength compared to existing alloys, which would make it possible to meet the still existing demands of reducing the thickness of the products and of developing solutions with high mechanical properties for battery coolers with the aim of improving their contribution to the overall strength of the structures protecting the batteries (which includes not only the thermal coolers but also the parts encapsulating the batteries, which may or may not be integrated into the body of the vehicle). [Means for solving the problem]

[0011] The applicant has unexpectedly determined a range of compositions that can improve mechanical strength without compromising corrosion resistance or brazeability. As an example, the target according to the present invention is a yield strength Rp of about 130 MPa or more, preferably 150 MPa, preferably 180 MPa, or even about 190 MPa or more, or even about 200 MPa or more. 0.2 can be achieved on industrial strip or plate after brazing.

[0012] The solution according to the invention is based on at least one of the following elements, which may in particular concern the composition of the alloy of the core layer, the configuration of the flat and pressed parts and also the manufacturing method: - in particular the use of a core layer made of a 6xxx series alloy having a composition as described according to the invention, preferably while maintaining a solidus temperature of, for example, above 615° C., when the core is clad with a brazing layer comprising an aluminium alloy of the 4xxx series, such as for example the alloys AA4343 or AA4045, having a solidus temperature of about 577° C. Generally, the solidus temperature of the core layer made of a 6xxx series alloy is preferably at least 20° C., preferably at least 30° C., preferably at least 40° C. higher than the solidus temperature of the brazing layer; the use of sacrificial layers on both sides of this core layer made of an alloy of the 6xxx series for the flat part 11 of the heat exchanger in order to ensure good corrosion resistance on the outside of the heat exchanger, i.e. on the side of the flat part 11 opposite to the side on which the pressed part 12 is located. - assembling, as shown in FIG. 2, a flat part 11 having a core layer 18 made of a 6xxx alloy clad on both sides with a sacrificial layer 16 with another part 12 having a core layer 18 made of a 6xxx alloy clad on one side with a brazing layer 17 and on the other side with a sacrificial layer 16 and pressed, forming a channel 13 between the flat part 11 and the pressed part 12. After assembly, according to the non-limiting configuration of FIG. 2, the brazing layer 17 of the pressed part 12 is between the core layer 18 made of a 6xxx alloy of the pressed part 12 and one of the sacrificial layers 16 of the flat part 11. It should be noted that the two core layers 18 made of a 6xxx alloy or the two sacrificial layers 16 can have the same or different compositions. It should also be noted that according to a variant, it is conceivable that a sacrificial layer can be present between the core layer 18 made of a 6xxx alloy and the brazing layer 17. - brazing (for example in a controlled atmosphere with controlled amounts of nitrogen or argon and / or oxygen) in a CAB furnace, for example at temperatures preferably below 615° C., preferably below 610° C., preferably below 605° C. Above 570° C., limiting the amount of oxygen to less than 100 ppm, preferably below 50 ppm, makes it possible to improve the quality of the braze. - Preferably ensure cooling below 380°C down to 100°C at the end of the brazing cycle, preferably at a rate of more than 25°C / min, preferably more than 40°C / min, preferably more than 50°C / min. Rapid cooling reduces the hardening potential of the alloy, especially Rp 0.2 This makes it possible to avoid or reduce the formation of coarse-sized (Mg,Si) type precipitates, for example larger than 150 nm, which may reduce the - Optionally adding a post-braze tempering step, preferably at a temperature between 180 and 220°C, preferably for a duration of less than 6 hours, suitably less than 3 hours, preferably less than 2 hours (e.g. 195°C for 2 hours or 205°C for 30 minutes).

[0013] The present invention therefore relates to a strip or plate intended for the manufacture of brazed heat exchangers, preferably battery coolers for electric vehicles, which comprises, preferably consists of, a core layer, optionally a coating layer on one or both sides of the core layer, and optionally an intermediate layer on one or both sides of the core layer, which is placed between the core layer and the coating layer, wherein the core layer comprises (in % by weight): - Si: 0.45-0.75; preferably 0.50-0.70%; preferably 0.55-0.65%; - Fe: 0.10-0.40%; preferably 0.12-0.35%; preferably 0.14-0.30%; preferably more than 0.18-0.26%; Cu: according to a first variant, ≦0.50%; preferably ≦0.45%; preferably ≦0.25%; preferably ≦0.15%; and preferably >0.05%; or according to a second variant, preferably 0.25-0.45%; preferably 0.29-0.40%; Mn: ≦0.30%; preferably ≦0.20%; preferably ≦0.15%; preferably ≦0.10%; - Mg: 0.25-0.56%; preferably 0.25-0.45%; preferably 0.30-0.39%; - Ti: <0.050%; preferably <0.045%; preferably <0.040%; - Optional V: 0.05~0.16%; - unavoidable impurities: <0.05% each and <0.15% in total; - The remainder is aluminum; The present invention relates to strip or plate materials made of 6xxx series aluminum alloys having the following composition.

[0014] The present invention relates to a set of two plates or strips, - a flat part formed from the strip or plate material according to the invention; - a pressed part formed from the strip or plate material according to the invention; comprising, and preferably consisting of; Also covered are sets in which two parts are intended to be assembled by brazing, where a channel is formed by deformation of the pressed part and the outermost layer of the pressed part and / or flat part in contact with another part is the brazing layer.

[0015] The present invention relates to a method for producing a strip or plate material, - Casting step of core alloy plate; - optionally a homogenization step of the plate at a temperature of 450-580°C, preferably 520-560°C, for 1-24 hours; - an optional cladding step with a cladding aluminum alloy on one or both sides of the core layer and possibly with an interlayer aluminum alloy on one or both sides of the core layer; - a pre-heating step at a temperature of 400-550°C, preferably 450-530°C, preferably 480-510°C, preferably with a hold at the maximum temperature for less than 30 hours, preferably less than 20 hours, preferably less than 12 hours, more preferably less than 3 hours; - a step of hot rolling of the optionally homogenized and optionally clad plate to a thickness of 2-6 mm at a temperature of 390-530 ° C, preferably 470-530 ° C; - cold rolling to the desired thickness, the thickness of the strip or plate after cold rolling being preferably between 0.15 and 3 mm; a heat treatment step in a continuous furnace at a temperature of 250-560°C, preferably 320-430°C, preferably 320-360°C, with a hold at maximum temperature for less than 5 minutes, preferably less than 1 minute, preferably less than 30 seconds and preferably more than 15 seconds, or in a batch furnace, i.e. a furnace operating discontinuously, at a temperature of 250-390°C, preferably 310-360°C, with a hold at maximum temperature for less than 3 hours, preferably less than 2 hours, preferably less than 1 hour, so as to obtain a recrystallization of small particles; The present invention also covers a manufacturing method including the successive steps of:

[0016] The invention also relates to a heat exchanger which is manufactured at least partly from a strip or plate according to the invention or from a set of two plates or strips according to the invention.

[0017] The invention also relates to the use of a strip or plate according to the invention or a set of two plates or strips according to the invention for the manufacture of a heat exchanger, preferably a battery cooler for an electric vehicle. [Brief description of the drawings]

[0018] [Figure 1] 1 is a cross-sectional view illustrating a current design of a battery cooler for an electric vehicle. [Diagram 2] 1 is a cross-sectional view illustrating a battery cooler design for an electric vehicle according to the present invention; [Diagram 3] FIG. 2 is a diagram depicting the assembly of plates for the brazeability test of Example 1. [Figure 4] FIG. 1 depicts the assembly and pitting analysis during SWAAT corrosion resistance testing of Example 3. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] In this specification and claims, unless otherwise indicated: - The designations of aluminum alloys are adapted from the Aluminum Association nomenclature; - The contents of chemical elements are expressed as mass percentages.

[0020] [Aluminum alloy core layer] The composition limits of the 6xxxx series aluminum alloy of the core layer used according to the present invention, expressed in mass percentages, can be justified as follows:

[0021] Silicon: A minimum content of 0.45% Si allows for improved mechanical properties, especially due to the formation of hard precipitates containing magnesium and silicon during tempering after brazing. The silicon content is therefore preferably 0.45% or more, or 0.46% or more, or 0.47% or more, or 0.48% or more, or 0.49% or more, or 0.50% or more, or 0.51% or more, or 0.52% or more, or 0.53% or more, or 0.54% or more, or 0.55% or more.

[0022] An excessively high Si content can lower the solidus temperature of the core and jeopardize brazing, and therefore it is preferred to limit the Si content to 0.75% or less, or 0.74% or less, or 0.73% or less, or 0.72% or less, or 0.71% or less, or 0.70% or less, or 0.69% or less, or 0.68% or less, or 0.67% or less, or 0.66% or less, or 0.65% or less.

[0023] Preferably, the mass ratio of Mg / Si is from 0.4 to 1.0, preferably from 0.5 to 0.9.

[0024] Iron: A maximum Fe content of 0.40%, or 0.39%, or 0.38%, or 0.37%, or 0.36%, or 0.35%, or 0.34%, or 0.33%, or 0.32%, or 0.31%, or 0.30%, or 0.29%, or 0.28%, or 0.27%, or 0.26% may also be advantageous for corrosion resistance and formability, especially by reducing the fraction of coarse precipitates containing Fe. However, it is not necessary to go down to very low contents, for example less than 0.08%, due to the possible high cost. Therefore, the preferred minimum Fe content is 0.10%, or 0.11%, or 0.12%, or 0.13%, or 0.14%, or 0.15%, or 0.16%, or 0.17%, or 0.18%.

[0025] Copper: Cu is a hardening element that contributes to mechanical strength. If an additional layer is present, a copper gradient is created during brazing, which has the effect of reducing the corrosion of the internal side of the exchanger, i.e. the side of the channel through which the fluid circulates. However, above a certain content, there is a higher risk of crack formation during casting and the susceptibility to corrosion in the core may increase. Coarse intermetallic compounds may also form during casting, which impair the homogeneity of the metal and constitute corrosion initiation sites. Cu is also an element that reduces the solidus temperature. The Cu content is therefore 0.50% or less, or 0.49% or less, or 0.48% or less, or 0.47% or less, or 0.46% or less, or 0.45% or less, or 0.40% or less, or 0.35% or less, or 0.30% or less, or 0.25% or less, or 0.20% or less, or 0.15% or less. Preferably, the Cu content is greater than 0.05%, or greater than or equal to 0.20%, or greater than or equal to 0.21%, or greater than or equal to 0.22%, or greater than or equal to 0.23%, or greater than or equal to 0.24%, or greater than or equal to 0.25%, or greater than or equal to 0.26%, or greater than or equal to 0.27%, or greater than or equal to 0.28%, or greater than or equal to 0.29%.

[0026] Manganese: The addition of Mn can allow the solidus to be raised, for which the Mn content is preferably 0.01% or more, or 0.02% or more, or 0.025% or more, or 0.03% or more, or 0.04% or more, or 0.05% or more, or 0.06% or more, or 0.07% or more, or 0.08% or more, or 0.09% or more, or 0.10% or more. In order to avoid the formation of numerous coarse phases during casting, which may reduce the formability, and the formation of dispersoids, which may act as nucleation sites for Mg-containing precipitates and reduce the hardenability during cooling of the braze, it is recommended to limit the Mn content to 0.30%, or 0.29%, or 0.28%, or 0.27%, or 0.26%, or 0.25%, or 0.24%, or 0.23%, or 0.22%, or 0.21%, or 0.20%, or 0.19%, or 0.18%, or 0.17%, or 0.16%, or 0.15%, or 0.14%, or 0.13%, or 0.12%, or 0.11%, or 0.10%. Mechanical properties, in particular Rp 0.2 To maximize this, it is preferred to limit the Mn content to less than or equal to 0.10%.

[0027] Magnesium: The Mg content according to the invention is controlled to be able to braze together two parts (flat part and pressed part), each having a core made of a 6xxx series aluminum alloy. This would be different if one of the two cores was made of a 3xxx series aluminum alloy. Mg is an element that can combine with silicon to create structural hardening during tempering after brazing. Also, the minimum Mg content according to the invention is preferably 0.25% or more, or 0.26% or more, or 0.27% or more, or 0.28% or more, or 0.29% or more, or 0.30% or more, or 0.31% or more, or 0.32% or more, or 0.33% or more. Furthermore, the maximum Mg content according to the present invention is preferably 0.56% or less, or 0.55% or less, or 0.54% or less, or 0.53% or less, or 0.52% or less, or 0.51% or less, or 0.50% or less, or 0.49% or less, or 0.48% or less, or 0.47% or less, or 0.46% or less, or 0.45% or less, or 0.44% or less, or 0.43% or less, or 0.42% or less, or 0.41% or less, or 0.40% or less, or 0.39% or less.

[0028] Titanium: Ti may make it possible to control the grain size during casting. Its content according to the invention is preferably less than 0.050%, less than 0.049%, or less than 0.048%, or less than 0.047%, or less than 0.046%, or less than 0.045%, or less than 0.044%, or less than 0.043%, or less than 0.042%, or less than 0.041%, or less than 0.040%.

[0029] Vanadium: Vanadium may optionally be added to ensure supplementary hardening and to increase the solidus temperature of the alloy. If its content exceeds 0.16%, primaries may form during casting. Its content according to the invention is preferably less than 0.16%, or less than 0.15%, or less than 0.14%, or less than 0.13%, or less than 0.12%, or less than 0.11%, or less than 0.10%. Preferably, if V is added, its minimum content is 0.05%.

[0030] Preferably, the solidus temperature of the 6xxx series aluminium of the core layer is above 595° C., preferably above 600° C., preferably above 605° C., preferably above 610° C., preferably above 615° C. Preferably, the solidus temperature of the core layer made of a 6xxx series alloy is at least 20° C., preferably at least 30° C., preferably at least 40° C. higher than the solidus temperature of the brazing layer. The solidus temperature of the 6xxx series aluminium of the core layer must be adapted depending on the brazing conditions in a manner known to the skilled person.

[0031] It should be noted that the 6xxx series aluminum alloy of the core layer of the flat parts and the pressed parts can be the same alloy or two different alloys. Preferably, it is the same alloy.

[0032] [Aluminum alloy coating layer] According to the invention, the covering layer can be a sacrificial layer or a brazing layer.

[0033] Sacrificial Layer: According to one variant of the invention, the strip or plate comprises, on at least one side of the core layer 18, a coating layer which is a sacrificial layer 16. Preferably, the aluminium alloy of the sacrificial layer 16 comprises less than 2.50% by weight of Zn, and preferably at least 0.50% by weight.

[0034] According to one variant of the invention, the aluminium alloy of the sacrificial layer is chosen from among aluminium alloys of the 1xxx, 7xxx or 3xxx series, preferably of the 7xxx or 3xxx series.

[0035] According to one variant, the aluminum alloy of the sacrificial layer may preferably be a 7xxx series aluminum alloy having the following composition, in mass percentages: less than 0.50% Si; less than 0.50% Fe; less than 0.25% Cu; less than 0.30% Mn; less than 0.20%, preferably less than 0.15% Mg; 0.70 to 5.00%, preferably 0.70 to less than 4.50%, and according to one variant 0.50% to less than 2.50%, preferably 0.70% to less than 2.50%, preferably more than 0.80% to less than 1.30% Zn; less than 0.15% Ti; other elements less than 0.05% each and less than 0.15% in total; the remainder being aluminum.

[0036] As an example, composition AA7072 is an aluminum alloy that may be suitable as a sacrificial layer according to the present invention, with the composition, in mass percentages: less than 0.05% Si; less than 0.05% Fe; less than 0.10% Cu; less than 0.10% Mn; less than 0.10% Mg; 0.80-1.30% Zn; less than 0.05% each and less than 0.15% total of other elements; the balance being aluminum.

[0037] According to another variant, the aluminum alloy of the sacrificial layer may be a 3xxx series aluminum alloy, preferably having the following composition in mass percentages: 0.10-0.35% Si; less than 0.70% Fe; less than 0.20% Cu; 0.70-2.00%, preferably 0.90-1.30% Mn; 0.70-5.00%, preferably 0.70 to less than 4.50%, preferably 0.70 to less than 2.50%, preferably more than 0.80% to less than 1.30% Zn; less than 0.15% Ti; other elements less than 0.05% each and less than 0.15% in total; the remainder being aluminum.

[0038] Suitable values, by mass percentage, of each element of 3xxx or 7xxx series alloys that may be suitable as sacrificial anodes in accordance with the present invention are shown by way of example in Table 1 below (columns 3xxx-1, 7xxx-1 and 7xxx-2).

[0039] [Table 1]

[0040] Brazing layer: The aluminum alloy of the brazing layer is preferably a 4xxx series aluminum alloy with a liquidus temperature sufficiently low compared to the solidus of the core alloy to provide a sufficient temperature range for brazing, acceptable mechanical strength and good leakage properties. These alloys may contain additional elements, such as strontium, preferably in a mass content of less than 0.05%.

[0041] According to one variant, the brazing alloy of the invention comprises Y, Sn and / or Bi. This variant is particularly advantageous for fluxless brazing. Preferably, the brazing alloy comprises: - 0.01-0.10%, preferably 0.015-0.08%, preferably 0.02-0.065% Y; - 0.01 to 0.10%, preferably 0.015 to 0.08%, preferably 0.02 to 0.065% Sn; and / or according to a first variant, at most 0.04%, preferably at most 0.03%, preferably at most 0.02% Bi; or according to a second variant, at most 0.15%, preferably at most 0.12%, preferably less than 0.10% and preferably at least 0.05%, preferably more than 0.06% Bi.

[0042] Preferably, the aluminum alloy of the brazing layer does not contain Bi.

[0043] Preferably, the aluminum alloy of the brazing layer is a 4xxx series alloy containing 4.00 to 13.00 mass % Si and less than 1.00 mass % Fe.

[0044] Preferably, the aluminium alloy of the brazing layer of the 4xxx series comprises (in mass %): - Si: 5.00-13.00%, preferably 6.00-11.00%; Fe: less than 0.60%, preferably less than 0.50%, preferably less than 0.30%; Cu: less than 0.40%, preferably less than 0.10%, preferably less than 0.05%; Mn: less than 0.20%, preferably less than 0.10%, preferably less than 0.05%; Mg: less than 0.20% according to a first variant, preferably less than 0.10%, preferably less than 0.05%; or between 0.50 and 2.50%, preferably between 1.00 and 2.00%, according to a second variant; Zn: less than 0.20%, preferably less than 0.10%, preferably less than 0.05%, preferably less than 0.02%; Ti: less than 0.30%, preferably less than 0.10%, preferably less than 0.05%; - possibly Bi, Y, Sr and / or Sn; - Other elements: less than 0.05% each and less than 0.15% in total; - The rest is aluminum.

[0045] As an example, the composition AA4045 is an aluminum alloy that may be suitable as an alloy for the brazing layer according to the present invention, with the composition, in mass percentages: 9.0-11.0% Si, less than 0.80% Fe, less than 0.30% Cu, less than 0.05% Mn, less than 0.05% Mg, less than 0.10% Zn, less than 0.20% Ti, less than 0.05% each and less than 0.15% in total of other elements, the balance being aluminum.

[0046] As an example, the above composition preferably contains less than 0.60% Fe.

[0047] As an example, the above composition preferably contains less than 0.10% Cu.

[0048] As an example, composition AA4343 is an aluminum alloy that may be suitable as a brazing alloy according to the present invention, with the composition, in mass percentages: 6.80-8.20% Si, less than 0.80% Fe, less than 0.25% Cu, less than 0.10% Mn, less than 0.05% Mg, less than 0.05% each and less than 0.15% total of other elements, the balance being aluminum.

[0049] As an example, the above composition preferably contains less than 0.30% Fe.

[0050] As an example, the above composition preferably contains less than 0.10% Cu.

[0051] As an example, composition AA4004 is an aluminum alloy that may be suitable as a brazing alloy according to the present invention, with the composition, in mass percentages: 9.00-10.50% Si, less than 0.80% Fe, less than 0.25% Cu, less than 0.10% Mn, 1.00-2.00% Mg, less than 0.20% Zn, less than 0.05% each and less than 0.15% in total of other elements, the balance being aluminum.

[0052] As an example, composition AA4104 is an aluminum alloy that may be suitable as a brazing alloy according to the present invention, with the composition, in mass percentages: 9.00-10.50% Si, less than 0.80% Fe, less than 0.25% Cu, less than 0.10% Mn, 1.00-2.00% Mg, less than 0.20% Zn, 0.02-0.20% Bi, less than 0.05% each and less than 0.15% in total of other elements, the balance being aluminum.

[0053] [Aluminum alloy in the middle layer] According to one embodiment, the strip or plate according to the invention is clad on one or both sides of the core layer with a so-called interlayer aluminum alloy, preferably of the 1xxx or 3xxx series, which is placed between the core layer and a coating layer, preferably a brazing layer, and which preferably comprises (in % by weight): - Si: less than 0.50%, more preferably less than 0.20%; Fe: less than 0.70%, better still less than 0.30%, even better still less than 0.20%; Mn: 0.30-1.40%, better still 0.50-0.90%, better still 0.60-0.80% or according to one variant 1.00-1.30%; Cu: less than 0.30, preferably less than 0.10%, even more preferably less than 0.05%; - possibly Mg, Zn and / or In; - Other elements, each <0.05% and total <0.15%; - The rest is aluminum.

[0054] Preferably, the interlayer aluminium alloy of the strip or plate according to the invention contains (in % by mass): Si<0.15%; Fe<0.20%; Cu<0.10%; Mn 0.60-0.80%; Mg<0.02% according to a first variant or Mg<0.50%, preferably <0.25% according to a second variant; other elements, each <0.05% and in total <0.15%, the remainder being aluminium.

[0055] Preferably, the intercalated aluminium alloy is an AA3xxx series alloy.

[0056] According to one variant, the intercalated aluminum alloy may further comprise: - Zn according to a content of 1.5 to 2.3%; and / or - In according to a content of 0.005-0.04%.

[0057] According to one variant, the strip or plate according to the invention comprises an intermediate layer between the core and the coating layer only if the coating layer is a brazing layer.

[0058] According to one variant, the strip or plate according to the invention does not comprise an intermediate layer.

[0059] [Strip or plank and set of two strips or planks] Strips or plates: The strip or plate according to the invention is a so-called brazed strip or plate which can be used for the manufacture of various parts of heat exchangers, such as tubes, plates, manifolds, battery cooling systems for electric vehicles, etc.

[0060] The strip or plate according to the invention may have a construction with several layers, in particular with 2, 3, 4 or 5 layers.

[0061] A configuration with two layers includes a core layer that is clad on only one side with a coating layer, specifically a braze or sacrificial layer.

[0062] A configuration with three layers can include: - A core layer clad on both sides with a brazing layer; - or a core layer clad on both sides with a sacrificial layer; - or a core layer which is itself clad on one side only with a brazing or sacrificial layer, preferably an intermediate layer clad with a brazing layer; - Or a core layer clad with a brazing layer on one side and a sacrificial layer on the other side.

[0063] A configuration with four layers can include: - a core layer clad on a first side with an intermediate layer which is itself clad with a brazing or sacrificial layer, preferably a brazing layer, and on the other side with a brazing layer; or a core layer clad on a first side with an intermediate layer which is itself clad with a brazing or sacrificial layer, preferably a brazing layer, and on the other side with a sacrificial layer.

[0064] A configuration with five layers includes a core layer that is clad on both sides with an intermediate layer that is itself clad with a braze or sacrificial layer, preferably a braze layer.

[0065] In each of the above configurations, when two brazing layers, two intermediate layers or two sacrificial layers are provided, the layers may be identical or different in composition. Preferably, the layers are identical in composition.

[0066] A preferred configuration is a three-layer configuration including: - A core layer clad on both sides with a sacrificial layer; - Or a core layer clad on one side with a sacrificial layer and on the other side with a brazing layer.

[0067] According to one variant, there may be at least one intermediate layer between the core layer and the sacrificial or brazing layer, although preferably no intermediate layer is present in the strip or plate according to the invention.

[0068] Preferably, the strip or plate material according to the present invention comprises a core layer made of a 6xxx series aluminum alloy, a coating layer on one or both sides of the core layer and, optionally, an intermediate layer on one or both sides of the core layer, located between the core layer and the coating layer.

[0069] According to a first variant, the strip or plate according to the invention comprises a coating layer on only one side of the core layer and: - the coating layer is a brazed layer; or The covering layer is a sacrificial layer.

[0070] According to a second variant, the strip or plate according to the invention comprises a coating layer on both sides of a core layer and: - one of the coating layers is a sacrificial layer and the other coating layer is a brazing layer; or - Two of the coating layers are sacrificial; or - The two coating layers are brazing layers.

[0071] As regards the total thickness of the strip or plate according to the invention, this is preferably between 0.40 and 2.50 mm.

[0072] The thicknesses discussed here correspond to the thickness before brazing. It should be noted that for the thickness of each layer, this is a target value, and a tolerance of about 2% is generally allowed for these values ​​in the field of clad strips or plates for heat exchangers.

[0073] According to a first variant, in which the strip or plate according to the invention is intended for the production of flat parts, the minimum total thickness of the strip or plate is 1.05 mm, or 1.15 mm, or 1.25 mm, or 1.35 mm, or 1.45 mm, or 1.55 mm, or 1.65 mm, or 1.75 mm, or 1.85 mm, or 1.95 mm. According to this first variant, the maximum total thickness of the strip or plate is preferably 2.50 mm, or 2.40 mm, or 2.30 mm, or 2.20 mm, or 2.10 mm.

[0074] According to a second variant, in which the strip or plate according to the invention is intended for the manufacture of pressed parts, the minimum total thickness of the strip or plate is 0.50 mm, or 0.60 mm, or 0.70 mm, or 0.80 mm, or 0.90 mm. According to this second variant, the maximum total thickness of the strip or plate is preferably 2.50 mm, or 2.30 mm, or 2.10 mm, or 1.90 mm, or 1.70 mm, or 1.50 mm, or 1.30 mm, or 1.10 mm.

[0075] Regarding the thickness of the intermediate or sacrificial layer, this thickness preferably represents 4 to 15% of the total thickness of the strip or plate according to the invention. The minimum thickness of the intermediate or sacrificial layer preferably represents 5%, or 6%, or 7%, or 8%, or 9% of the total thickness of the strip or plate according to the invention. The maximum thickness of the intermediate or sacrificial layer preferably represents 14%, or 13%, or 12%, or 11% of the total thickness of the strip or plate according to the invention.

[0076] With regard to the thickness of the brazing layer, this thickness preferably represents 3-15% of the total thickness of the strip or plate according to the invention. The minimum thickness of the brazing layer preferably represents 4% of the total thickness of the strip or plate according to the invention. The maximum thickness of the brazing layer preferably represents 14%, or 13%, or 12%, or 11%, or 10%, or 9%, or 8%, or 7%, or 6% of the total thickness of the strip or plate according to the invention.

[0077] Set of 2 planks or strips: The plates or strips according to the invention, after any forming, can be combined with one another to form a heat exchanger with channels. A set of two plates or strips according to the invention can be assembled but before brazing, or after brazing. Brazing does not modify the configuration, i.e. the sequence of the different layers and the respective position of the flat parts in relation to the pressed parts.

[0078] According to the invention, a set of two plates or strips is provided: - a flat part formed from the strip or plate material according to the invention; - a pressed part made from the strip or plate material according to the invention; comprising, and preferably consisting of; The two parts are intended to be assembled by brazing, where the deformation of the pressed part forms a channel, and the outermost layer of the pressed part and / or flat part in contact with another part is the brazing layer.

[0079] The assembly of two plates or strips according to the invention can take the form of different variants.

[0080] According to a first preferred variant: - one of the flat or pressed parts is made up of a core according to the invention, clad on both sides with a sacrificial layer, the other of the pressed or flat parts is made up of a core according to the invention, clad on one side with any intermediate layer and a brazing layer and on the other side with a sacrificial layer.

[0081] According to a second preferred variant, the two flat and pressed parts are made up of a core according to the invention, clad on one side with optional intermediate and brazing layers and on the other side with a sacrificial layer.

[0082] In each of the above variations, the braze layer of at least one part is located between the flat part and the pressed part.

[0083] [method] The present invention relates to a method for producing a strip or plate material, - Casting step of core alloy plate; - optionally a homogenization step of the plate at a temperature of 450-580°C, preferably 520-560°C, for 1-24 hours; - an optional cladding step with a cladding aluminum alloy on one or both sides of the core layer and possibly with an interlayer aluminum alloy on one or both sides of the core layer; - a pre-heating step at a temperature of 400-550°C, preferably 450-530°C, preferably 480-510°C, preferably with a hold at the maximum temperature for less than 30 hours, preferably less than 20 hours, preferably less than 12 hours, more preferably less than 3 hours; - a step of hot rolling of the optionally homogenized and optionally clad plate to a thickness of 2-6 mm at a temperature of 390-530 ° C, preferably 470-530 ° C; - cold rolling to the desired thickness, the thickness of the strip or plate after cold rolling being preferably between 0.15 and 3 mm; - a heat treatment step in a continuous furnace at a temperature of 250-560°C, preferably 320-430°C, preferably 320-360°C, with a hold at maximum temperature for less than 5 minutes, preferably less than 1 minute, preferably less than 30 seconds and preferably more than 15 seconds, or in a batch furnace at a temperature of 250-390°C, preferably 310-360°C, with a hold at maximum temperature for less than 3 hours, preferably less than 2 hours, preferably less than 1 hour, so as to obtain a recrystallization of small grains; The present invention also relates to a manufacturing method comprising the steps of:

[0084] The coating alloy of the method according to the invention may in particular be a brazing alloy or a sacrificial layer, or two brazing alloys, or two sacrificial layers, or a brazing alloy and a sacrificial layer.

[0085] Preferably, no intermediate annealing is performed during the rolling steps in the method according to the invention.

[0086] Prior to the application of any cladding material, homogenization of the core layer alloy plate may be performed at a temperature of 450-580° C., preferably 520-560° C., preferably for 1-24 hours.

[0087] [use] The invention also relates to a heat exchanger at least partially manufactured from a strip or plate according to the invention or from an assembly of two strips or plates according to the invention.

[0088] The invention also relates to the use of a strip or plate according to the invention or an assembly of two plates or strips according to the invention for the manufacture of a heat exchanger, preferably a battery cooler for an electric vehicle.

[0089] The strip or plate material according to the invention can be used in particular in the manufacture of brazed heat exchangers for automobiles, such as, for example, engine cooling radiators, evaporators, heating radiators and charge air coolers, manifolds, battery coolers for electric vehicles, and in air conditioning systems.

[0090] The manufacture of the heat exchanger according to the invention can in particular comprise at least one of the following steps: - brazing in a CAB (Controlled Atmosphere) furnace, preferably at a temperature of 590-615°C, preferably 590-610°C, preferably 590-605°C, preferably 590-600°C; - ensuring cooling at the end of the brazing cycle, preferably having a rate of more than 25°C / min, preferably more than 35°C / min, preferably more than 50°C / min, from below 380°C down to 100°C; - carrying out a post-braze tempering step at a temperature between 150 and 240°C, preferably between 180 and 220°C (for example about 195°C for 2 hours or 205°C for 30 minutes) for a duration preferably less than 6 hours, preferably less than 3 hours, preferably less than 2 hours. Preferably, the minimum temperature of the post-braze tempering is above 180°C, or 181°C or more, or 182°C or more, or 183°C or more, or 184°C or more, or 185°C or more, or 186°C or more, or 187°C or more, or 188°C or more, or 189°C or more, or 190°C or more. An increase in the post-braze tempering temperature may allow a reduction in the duration of this tempering. As an example, for a post-braze tempering temperature of 185°C or more, the duration may be less than 4 hours. EXAMPLES

[0091] Example 1: Brazeability Different ingots of aluminum alloys for the core layer, the brazing layer and the sacrificial layer were cast by vertical semi-continuous casting (DC casting) using aluminum alloys having the compositions, in mass percentages, shown in Table 2 below.

[0092] [Table 2]

[0093] Before the mutual assembly of the different layers: - the aluminum alloy ingot of the core layer was homogenized (at a temperature above 530°C for more than 2 hours but less than 24 hours) and hot rolled at a temperature of 380-500°C to a thickness of about 30 mm; - the alloy ingot of the brazing layer was scalped and then hot rolled to a thickness of 1.8 mm at a temperature of about 480-500 ° C; The sacrificial layer alloy ingot was hot rolled at a temperature of about 480-500°C to a thickness of about 3.5 mm.

[0094] After brushing of the contact surfaces, a 35.3 mm thick sandwich structure was made with the following configuration: brazing layer / core layer / sacrificial layer. The brazing layer accounted for approximately 5% of the total thickness of the sandwich structure, and the sacrificial layer accounted for approximately 10% of the total thickness of the sandwich structure.

[0095] Two sandwich structures were made: - Configuration 1: brazing layer-1 / core layer-1 / sacrificial layer; - Configuration 2: brazing layer-1 / core layer-2 / sacrificial layer.

[0096] The sandwich structure was then preheated at a temperature of about 490° C. for less than 5 hours and then hot rolled to a thickness of about 1.5 mm or about 0.8 mm.

[0097] Annealing was carried out at about 360° C. for 2 hours.

[0098] The sandwich structure with a thickness of about 0.8 mm was pressed to create two lines to obtain a pressed sheet, as illustrated in Figure 3. The sandwich structure with a thickness of about 1.5 mm was not pressed to obtain an unpressed or flat sheet.

[0099] The brazeability of the different sandwich structures was then evaluated. The brazing tests were carried out according to the following protocol, which makes it possible to simulate an assembly brazing between pressed and non-pressed sheets. For this, sheets of 50 mm x 60 mm were pressed in the absence of lubricant to add two longitudinal pressing lines 3 as illustrated in FIG. 3. The pressed and non-pressed sheets were then degreased with an acetone solution and then air dried. Pressed and non-pressed sheets of the same configuration and composition were then assembled as illustrated in FIG. 3. In FIG. 3, reference number 1 corresponds to the pressed sheet, reference number 2 corresponds to the non-pressed sheet, reference number 3 corresponds to the two pressing lines, reference number 16 corresponds to the sacrificial layer, reference number 17 corresponds to the brazing layer made of aluminium alloy of the 4xxx series and reference number 18 corresponds to the core made of aluminium alloy of the 6xxx series. The assembled sheets are then coated on the brazing layer 17 with Nocolok® type 0 or 2 or 5 g / m 2 The brazing cycle was carried out at about 600° C. for about 2 minutes in a controlled atmosphere (O2<50 ppm).

[0100] The length of each brazed joint was then measured. For each configuration, three specimens were made. For each specimen, two measurements were made at the level of the two longitudinal pressing lines. The results can be expressed as brazed length in mm or as a percentage of the brazed length in relation to the maximum possible length. "A" corresponds to more than 90%; "B" corresponds to the range 50-90%; "C" corresponds to the range 10% to less than 50%; "D" corresponds to less than 10%.

[0101] The results of the brazing tests are shown in Table 3 below.

[0102] [Table 3]

[0103] 5g / m for all configurations 2 With this flux, excellent brazing properties were obtained.

[0104] Example 2: Mechanical properties of a three-layer sandwich structure The above-mentioned Example 1 samples (according to the configurations of Configuration-1 and Configuration-2) were subjected to different annealing, i.e., stripline type annealing (about 400°C for 30 seconds or about 550°C for 45 seconds) or batch type annealing (about 360°C for 2 hours) after cold rolling to a thickness of 1.5 mm.

[0105] CAB (Controlled Atmosphere) type brazing was carried out at about 600°C for about 2 minutes with cooling at a rate of more than 40°C / min down to below 380°C and down to 100°C.

[0106] This was followed by tempering at about 195°C for 2 hours.

[0107] Tensile mechanical properties were measured in the rolling direction after annealing and after annealing+brazing+tempering according to the ISO 6892-1 standard.

[0108] [Table 4]

[0109] The duration and temperature of annealing are Rp after annealing + brazing + tempering 0.2 In all cases, the Rp of the assembly does not seem to affect 0.2 is greater than 165 MPa. This value is greater for the assemblies with 6xxx-1 alloy cores (Configuration-1) that contain more magnesium than the assemblies with 6xxx-2 alloy cores (Configuration-2).

[0110] Example 3: Corrosion Measurements of corrosion resistance according to the SWAAT test were carried out for the configurations of Configuration-1 and Configuration-2 described in Examples 1 and 2 above, on samples with a thickness of about 1 mm, on the side clad with a sacrificial layer, and after annealing at about 360°C for 2 hours, followed by brazing at about 600°C for 2 minutes, and then tempering at about 195°C for 2 hours.

[0111] The corrosion resistance was determined using the following protocol: - for each configuration, prepare a specimen with dimensions of 126 mm (L direction) x 90 mm (TL direction), previously degreased with white absorbent paper soaked with acetone; - Protect the surface not to be tested (the surface clad with the brazing layer) as well as the four edges with a clear vinyl adhesive tape (e.g. 3M Vinyl 764 type) over a width of approximately 0.5 cm; - Clean the surface to be tested (the surface clad with the sacrificial layer) with absorbent paper soaked in acetone; - Place the specimen thus prepared on a rack at an inclination of approximately 60° to the horizontal; - A SWAAT (Sea Water Acidification with Acetic Acid Test) cyclic test according to the ASTM G85A3 standard is carried out on each sample, which in particular comprises a salt spray phase of 30 minutes alternating with a wet phase of 1 hour 30 minutes at a temperature of about 49°C.

[0112] Each sample was inspected for the number of pits every day for the entire duration of the test, i.e., 20 days. The pits were visible on the back of each sample by forming blisters in the adhesive tape applied on the non-tested side, as illustrated in Figure 4. In Figure 4, reference number 6 corresponds to the sample; reference number 7 corresponds to the adhesive tape; reference number 8 corresponds to the pits; and reference number 9 corresponds to the blisters formed by the pits.

[0113] From the results obtained, no pitting was observed after the test for 20 days for both Configuration-1 and Configuration-2.

[0114] The samples were then observed on polished cross-sections using a microscope: the depth of the (non-through) corrosion pits was less than 60 μm for two configurations, Configuration-1 and Configuration-2.

[0115] Example 4: Mechanical properties Simulation tests of the brazing cycle (heating at about 600°C, holding for 2 minutes, then cooling from 380°C to 100°C at a rate of more than 50°C / min) and post-braze tempering (several temperatures and holding durations were tested, see Table 6 below) were carried out on various compositions of 6xxx series aluminum alloy cores without cladding (see Table 5 below). Plates of 6xxx series aluminum alloys were obtained by homogenization at a temperature above 500°C for a duration of more than 3 hours, then hot rolling at a temperature between 350 and 450°C to a thickness of about 2.8 mm, then cold rolling to a thickness of about 0.8 mm, then annealing at a temperature between 440 and 500°C for a duration of 30 to 45 seconds.

[0116] [Table 5]

[0117] After annealing + brazing + tempering according to the ISO 6892-1 standard, the tensile mechanical properties were measured in the rolling direction, and the results are shown in Table 6 below.

[0118] [Table 6]

[0119] The 6xxx-4 alloys exhibited improved post-braze mechanical properties compared to the 6xxx-3 alloys (see Table 6 above) at the expense of lowering the solidus temperature to 618°C.

[0120] Example 5: Mechanical properties Castings of various compositions of 6xxx series aluminum alloys were carried out. Table 7 below shows the elemental contents of the various alloys expressed as mass percentages.

[0121] [Table 7]

[0122] Plates of 6xxx series aluminum alloys were obtained by homogenization at a temperature of about 540°C for a duration of about 6 hours (except for alloy B', which was not homogenized), followed by hot rolling at a temperature of about 490°C to a thickness of about 4.5 mm, followed by cold rolling to a thickness of about 2.0 mm, followed by annealing at a temperature of about 360°C for a duration of about 2 hours. Simulation tests of brazing cycle (heating at about 600°C, holding for 2 minutes, followed by cooling from 380°C to 100°C at a rate of more than 50°C / min) and post-braze tempering (195°C for 1 hour, 195°C for 4 hours, 205°C for 2 hours, or 210°C for 2 hours, see Table 8 below) were performed for alloys A-G in Table 7 above. The oxygen content during the brazing simulation was less than 50 ppm.

[0123] After annealing, brazing and tempering, the tensile mechanical properties were measured in the rolling direction according to the ISO 6892-1 standard. The results are shown in Table 8 below, where Rp 0.2 and Rm values ​​are expressed in MPa.

[0124] [Table 8]

[0125] Meanwhile, corrosion resistance tests (not shown here) were carried out for core alloys A, B, F and G placed in the form of a sandwich structure between brazing layer-1 (7.5% of the total thickness of the sandwich structure) in Table 2 above and sacrificial layer (10% of the total thickness of the sandwich structure) in Table 2 above. SWAAT tests were carried out according to the ASTM G85A3 standard (as described above in Example 3). The results were obtained by microscopic analysis on polished cross-sections after 40 days of testing. The total thickness of the sandwich structure was about 0.8 mm. Larger pitting depths were observed for core alloy F, confirming that the corrosion resistance of the sandwich structure containing core alloy F is not as good as that of the sandwich structure containing core alloys A, B and G.

[0126] Moreover, it should be noted that core alloy G contains Fe content that is less suitable for recycling.

[0127] Example 6: Mechanical properties Simulation tests of the brazing cycle (heating at about 600°C, holding for 2 minutes, then cooling from 380°C to 100°C at a rate of more than 50°C / min) and post-braze tempering (multiple temperatures and hold durations were tested, see Table 10 below) were performed on a plate including a core of 6xxx series aluminum alloy (Alloy 6xxx-5) clad on both sides with sacrificial layers of 7xxx series aluminum alloy (Alloy 7xxx-1), where each of the two sacrificial layers accounted for 10% of the total thickness of the plate. The composition of the aluminum alloy, in mass percentage, is given in Table 9 below.

[0128] [Table 9]

[0129] A core layer made of an aluminum alloy of the 6xxx series was homogenized at a temperature of 540-600°C for a duration of more than 3 hours and then assembled with two sacrificial layers made of an aluminum alloy of the 7xxx series, which had previously been hot rolled. The sandwich structure thus obtained was preheated, then hot rolled to a thickness of about 4 mm, then cold rolled to a thickness of about 2 mm, and then annealed at a temperature of about 350°C for a duration of about 30 minutes.

[0130] After annealing+brazing+tempering, the tensile mechanical properties were measured in the rolling direction according to the ISO 6892-1 standard, and the results are shown in Table 10 below.

[0131] [Table 10] [Explanation of symbols]

[0132] 1 Pressed sheet 2. Unpressed sheets 3 Press processing line 6. Samples 7 Adhesive Tape 8 Pitting corrosion 9. Swelling 11 Flat parts 12 Press processed parts 13 Channels 16, 17 Covering layer 18 Core Layer

Claims

1. A strip or plate intended for the manufacture of brazed heat exchangers, preferably battery coolers for electric vehicles, preferably comprises a core layer (18), optionally a covering layer (16, 17) on one or both sides of the core layer (18), and optionally an intermediate layer on one or both sides of the core layer (18) located between the core layer (18) and the covering layer (16, 17), wherein the core layer (18) comprises, in mass percentages: Si is 0.45 to 0.75%, preferably 0.50 to 0.70%, preferably 0.55 to 0.65%, Fe is 0.18-0.40%, preferably 0.18-0.35%, preferably 0.18-0.30%, preferably >0.18-0.26%, Cu, according to the first variant, ≦0.40%, preferably ≦0.25%, preferably ≦0.15% and preferably >0.05%, or according to the second variant, preferably between 0.25 and 0.40%, preferably between 0.29 and 0.40%, Mn ≦0.30%, preferably ≦0.20%, preferably ≦0.15%, preferably ≦0.10%, Mg: 0.25-0.56%, preferably 0.25-0.45%, preferably 0.30-0.39%, Ti <0.050%, preferably <0.045%, preferably <0.040%, optionally V from 0.05 to 0.16%, - unavoidable impurities each less than 0.05% and in total less than 0.15%, - The remainder is aluminum, The strip or plate material is made of a 6xxx series aluminum alloy having a composition as follows:

2. 2. The strip or plate material according to claim 1, characterized in that it comprises a core layer (18) made of a 6xxx series aluminum alloy, a coating layer (16, 17) on one or both sides of the core layer (18) and, optionally, an intermediate layer on one or both sides of the core layer (18) located between the core layer (18) and the coating layer (16, 17).

3. a coating layer (16, 17) on one side of the core layer; and the coating layer (16, 17) is a brazing layer (17), or the covering layer (16, 17) is a sacrificial layer (16); 3. The strip or plate material according to claim 2 ,

4. including coating layers (16, 17) on both sides of the core layer; and one of the coating layers (16, 17) is a sacrificial layer (16) and the other coating layer (16, 17) is a brazing layer (17), or the two covering layers (16, 17) are sacrificial layers (16), or - the two coating layers (16, 17) are brazed layers (17); 3. The strip or plate material according to claim 2 ,

5. 5. The strip or plate material according to claim 2, further comprising a coating layer, which is a sacrificial layer (16), on at least one side of the core layer (18), the aluminum alloy of which preferably contains less than 2.50% by weight, and preferably at least 0.50% by weight, of Zn.

6. 6. Strip or plate according to any one of claims 3 to 5, characterized in that the aluminium alloy of the sacrificial layer (16) is chosen from among alloys of the 1xxx, 7xxx or 3xxx series.

7. The aluminum alloy of the sacrificial layer (16) has a mass percentage of: - less than 0.50% Si; less than 0.50% Fe, - less than 0.25% Cu, - less than 0.30% Mn, less than 0.20%, preferably less than 0.15% Mg; - 0.50% to less than 2.50%, preferably 0.70% to less than 2.50%, preferably from more than 0.80% to less than 1.30% Zn; - less than 0.15% Ti, - less than 0.05% each and less than 0.15% in total of other elements, - The remainder is aluminum, 7. The strip or plate material according to claim 6, which is a 7xxx series alloy, preferably having the composition:

8. The aluminum alloy of the sacrificial layer (16) has a mass percentage of: - 0.10 to 0.35% Si, less than 0.70% Fe, - less than 0.20% Cu, - 0.70 to 2.00%, preferably 0.90 to 1.30% Mn, - from 0.80% to less than 1.30% Zn, - less than 0.15% Ti, - less than 0.05% each and less than 0.15% in total of other elements, - The remainder is aluminum, 7. The strip or plate material according to claim 6, which is a 3xxx type alloy, preferably having the composition:

9. The aluminum alloy of the brazing layer (17) preferably contains 4.00 to 13.00 mass% Si and less than 1.00 mass% Fe, in mass percentages: - Si: 5.00 to 13.00%, preferably 6.00 to 11.00%, Fe: less than 0.60%, preferably less than 0.50%, preferably less than 0.30%; Cu: less than 0.40%, preferably less than 0.10%, preferably less than 0.05%; Mn: less than 0.20%, preferably less than 0.10%, preferably less than 0.05%, Mg: less than 0.20% according to a first variant, preferably less than 0.10%, preferably less than 0.05%, or between 0.50 and 2.50%, preferably between 1.00 and 2.00%, according to a second variant; Zn: less than 0.20%, preferably less than 0.10%, preferably less than 0.05%, preferably less than 0.02%, Ti: less than 0.30%, preferably less than 0.10%, preferably less than 0.05%; optionally Bi, Y, Sr and / or Sn, Other elements: less than 0.05% each and less than 0.15% in total; - The remainder is aluminum, 5. The strip or plate material according to claim 3 or 4, which is a 4xxx-type alloy, more preferably having the composition:

10. In a set of two plates or strips, - a flat part (11) made from a strip or plate material according to any one of claims 1 to 9, preferably according to any one of claims 2 to 9, - a pressed part (12) made from a strip or plate material according to any one of claims 1 to 9, preferably according to any one of claims 2 to 9, and preferably consisting of A set of two parts intended to be assembled by brazing, in which a channel is formed by deformation of a pressed part (12), and the outermost layer of the pressed part (12) and / or the flat part (11) in contact with another part is a brazing layer (17).

11. In the method for producing a strip or plate material according to any one of claims 1 to 9, - casting the core alloy plate (18); - optionally a homogenization step of the plate at a temperature between 450 and 580°C, preferably between 520 and 560°C, for a period of 1 to 24 hours; an optional cladding step with a cladding aluminum alloy (16, 17) on one or both sides of the core layer (18) and optionally with an interlayer aluminum alloy on one or both sides of the core layer (18), - a pre-heating step at a temperature of 400-550°C, preferably 450-530°C, preferably 480-510°C, preferably with a hold at the maximum temperature for less than 30 hours, preferably less than 20 hours, preferably less than 12 hours, more preferably less than 3 hours; - a hot rolling step of the optionally homogenized and optionally clad plate to a thickness of 2 to 6 mm at a temperature between 390 and 530 °C, preferably between 470 and 530 °C, - cold rolling to the desired thickness, the thickness of the strip or plate after cold rolling being preferably between 0.15 and 3 mm, a heat treatment step in a continuous furnace at a temperature of 250-560°C, preferably 320-430°C, preferably 320-360°C, with a hold at maximum temperature for less than 5 minutes, preferably less than 1 minute, preferably less than 30 seconds and preferably more than 15 seconds, or in a batch furnace at a temperature of 250-390°C, preferably 310-360°C, with a hold at maximum temperature for less than 3 hours, preferably less than 2 hours, preferably less than 1 hour, so as to obtain a recrystallization of small grains; A manufacturing method comprising the successive steps of:

12. 10. A heat exchanger at least partially manufactured from a strip or plate material according to any one of claims 1 to 9, preferably from any one of claims 2 to 9, or from a set of two strips or plates according to claim 10.

13. Use of a strip or plate according to any one of claims 1 to 9, preferably according to any one of claims 2 to 9, or a set of two plates or strips according to claim 10, for the manufacture of a heat exchanger, preferably a battery cooler for an electric vehicle.

14. a brazing step in a CAB (Controlled Atmosphere) furnace, preferably at a temperature of 590-615°C, preferably 590-610°C, preferably 590-605°C, preferably 590-600°C, - a cooling step at the end of the brazing cycle, preferably having a rate of more than 25°C / min, preferably more than 35°C / min, preferably more than 50°C / min, from below 380°C down to 100°C; a tempering step after brazing, preferably at a temperature of 150-240°C, preferably 180-220°C, for a duration of preferably less than 6 hours, preferably less than 3 hours; The use according to claim 13, comprising at least one of the following:

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