Aluminum alloy clad plate, aluminum alloy structure, and vehicular cooler

Abstract

An aluminum alloy clad plate (1) comprises: a core material (2) which has a chemical composition comprising 0.10-0.40 mass% of Si, 0.40 mass% or less of Fe, 0.20 mass% or less of Cu, 0.30 mass% or less of Mn, 1.2-2.0 mass% of Mg, 0.10 mass% or less of Cr, 0.50 mass% or less of Zn, and 0.10 mass% or less of Ti, with the balance being Al and unavoidable impurities, in which the ratio of the Mg content to the Si content is 12 or less, and which has a liquid phase ratio of less than 4.4 mass% at 610°C; and a skin material (3) which comprises aluminum or an aluminum alloy and which is provided on at least one surface of the core material (2). The solidus temperature of the skin material (3) is 610°C or higher, and the Mg content is 0.10 mass% or less.

Description

Aluminum alloy clad plate, aluminum alloy structure and vehicle cooler

[0001] The present invention relates to an aluminum alloy clad plate, an aluminum alloy structure, and a vehicle cooler.

[0002] Metal structures such as vehicle coolers are formed by joining multiple metal parts together. When mass-producing such structures, the multiple metal parts are often joined by brazing from the viewpoints of productivity and stability of joining quality.

[0003] On the other hand, in recent years, in various fields such as automobiles, there has been a demand for weight reduction of products from the viewpoint of reducing environmental impact. Therefore, magnesium-containing aluminum alloys, such as 6000 series aluminum alloys, which have high specific strength, are widely used as metals constituting these products. For example, Patent Document 1 describes a cold age-hardenable aluminum alloy for heat exchangers containing Si≦0.7 wt%, 0.1 wt%≦Mg≦1 wt%, Fe≦0.3 wt%, 0.08 wt%≦Cu≦0.2 wt%, Ti≦0.2 wt%, Mn≦0.1 wt%, Cr≦0.1 wt%, and Zn≦0.1 wt%, with the balance consisting of inevitable impurities and aluminum.

[0004] WO 2005 / 10223

[0005] A simple method for increasing the strength of 6000 series aluminum alloys is to increase the Mg content. However, increasing the Mg content in 6000 series aluminum alloys lowers the solidus temperature of the aluminum alloy. In addition, in this case, the aluminum alloy is more likely to be corroded by the brazing filler metal during brazing, which makes it more likely to cause local melting of the aluminum alloy, known as erosion. As a result, when attempting to join a high-strength 6000 series aluminum alloy to a mating material by brazing, there is a problem in that it is difficult to maintain the shape of the structure during brazing.

[0006] As described above, when a member made of a 6000 series aluminum alloy is used in a structure formed by brazing, there is a limit to how much the Mg content can be increased in order to increase the strength of the structure after brazing while maintaining the shape of the structure during brazing.

[0007] The present invention has been made in view of the above background, and aims to provide an aluminum alloy clad plate that can suppress deformation of the structure during brazing and has high strength after brazing, an aluminum alloy structure that includes this clad plate, and a vehicle cooler.

[0008] One aspect of the present invention is a core material having a chemical composition containing Si (silicon): 0.10% by mass to 0.40% by mass, Fe (iron): 0% by mass to 0.40% by mass, Cu (copper): 0% by mass to 0.20% by mass, Mn (manganese): 0% by mass to 0.30% by mass, Mg (magnesium): 1.2% by mass to 2.0% by mass, Cr (chromium): 0% by mass to 0.10% by mass, Zn (zinc): 0% by mass to 0.50% by mass, and Ti (titanium): 0% by mass to 0.10% by mass, with the balance being Al (aluminum) and unavoidable impurities, wherein the ratio of the Mg content to the Si content (Mg / Si) is 12 or less, and the core material has a liquid phase fraction of less than 4.4% by mass at 610°C; and a skin material made of aluminum or an aluminum alloy and provided on at least one surface of the core material, wherein the solidus temperature of the skin material is 610°C or higher, The aluminum alloy clad plate has a Mg content of 0.10 mass % or less in the skin material.

[0009] The core material of the aluminum alloy clad plate (hereinafter referred to as clad plate) has the specific chemical composition. By setting the chemical composition of the core material within the specific range, fine MgSi can be precipitated in the core material after brazing is completed. As a result, the strength of the clad plate after brazing can be improved.

[0010] In addition, a skin material is provided on at least one side of the core material. Since the skin material has a solidus temperature within the specific range, it is not easily eroded by the brazing filler during brazing. Therefore, brazing the skin material to the mating material suppresses erosion of the core material, and thus suppresses deformation of the clad plate during brazing. Therefore, by using the clad plate, deformation of the structure during brazing can be suppressed. Furthermore, by setting the Mg content in the skin material within the specific range, a brazed joint can be easily formed between the skin material and the mating material.

[0011] Therefore, according to the above-mentioned aspect, it is possible to provide an aluminum alloy clad plate that can suppress deformation of the structure during brazing and has high strength after brazing, an aluminum alloy structure that includes this clad plate, and a vehicle cooler.

[0012] Fig. 1 is a cross-sectional view of an aluminum alloy clad plate in Example 1. Fig. 2 is an explanatory diagram showing a test method for a sag test in an experimental example.

[0013] (Aluminum alloy clad plate) The clad plate has a core material and a skin material provided on at least one side of the core material. The clad plate may have, for example, a two-layer structure consisting of a core material and a skin material laminated on one side of the core material, or a three-layer structure consisting of a core material and skin materials laminated on both sides of the core material. Furthermore, the clad plate may have, in addition to the core material and skin material, a layer made of an aluminum alloy different from these. From the viewpoint of more reliably obtaining the effect of suppressing deformation during brazing, it is preferable that the skin material be laminated on the core material. Furthermore, from the viewpoint of more easily forming a brazed joint with a mating material, it is preferable that the skin material be provided on the outermost surface of the clad plate.

[0014] [Core Material] The core material of the clad plate has a chemical composition containing Si: 0.10 to 0.40% by mass, Fe: 0 to 0.40% by mass, Cu: 0 to 0.20% by mass, Mn: 0 to 0.30% by mass, Mg: 1.2 to 2.0% by mass, Cr: 0 to 0.10% by mass, Zn: 0 to 0.50% by mass, and Ti: 0 to 0.10% by mass, with the remainder being Al and unavoidable impurities, and having a ratio Mg / Si of 12 or less of the Mg content to the Si content. The reasons for limiting the chemical composition of the core material will be explained in detail below.

[0015] Si: 0.10% by mass or more and 0.40% by mass or less The core material contains 0.10% by mass or more and 0.40% by mass or less of Si as an essential component. The Si in the core material dissolves in the Al matrix of the core material during brazing heat, and precipitates in the core material as Mg2Si after brazing is complete. The precipitated Mg2Si in the core material has the effect of improving the strength of the core material through precipitation strengthening.

[0016] In the clad plate, by setting the Si content in the core material within the specific range, fine MgSi is precipitated in the core material, thereby improving the strength of the clad plate after brazing. If the Si content in the core material is less than 0.10 mass%, the effect of improving strength by Si becomes insufficient, which may result in a decrease in the strength of the clad plate. From the viewpoint of more easily increasing the strength of the clad plate, the Si content in the core material is preferably 0.20 mass% or more, and more preferably 0.25 mass% or more.

[0017] On the other hand, if the Si content in the core material is excessively high, the liquid phase ratio of the core material during brazing tends to be high. Therefore, in this case, the strength of the core material is excessively reduced during brazing, which may lead to deformation of the clad plate. By setting the Si content in the core material to 0.40 mass% or less, preferably 0.35 mass% or less, this problem can be easily avoided.

[0018] The preferred range of the Si content in the core material can be determined by any combination of the upper and lower limits of the Si content described above. For example, the preferred range of the Si content in the core material may be 0.20% by mass to 0.40% by mass, 0.25% by mass to 0.40% by mass, 0.10% by mass to 0.35% by mass, or 0.20% by mass to 0.35% by mass.

[0019] Mg: 1.2% by mass or more and 2.0% by mass or less The core material contains 1.2% by mass or more and 2.0% by mass or less of Mg as an essential component. The ratio of the Mg content to the Si content in the core material, Mg / Si, is 12 or less. Like Si, Mg in the core material dissolves in the Al matrix of the core material during brazing heat. Some of the Mg dissolved in the Al matrix precipitates as Mg2Si in the core material after brazing is complete, improving the strength of the core material through precipitation strengthening. Furthermore, Mg that does not form Mg2Si dissolves in the Al matrix and improves the strength of the core material through solid solution strengthening.

[0020] In the clad plate, by setting the Mg content in the core material within the specific range, the strength of the clad plate after brazing can be improved. If the Mg content in the core material is less than 1.2 mass%, the effect of Mg in improving strength may be insufficient, which may result in a decrease in the strength of the clad plate. From the viewpoint of more easily increasing the strength of the clad plate, the Mg content in the core material is preferably 1.3 mass% or more, and more preferably 1.4 mass% or more.

[0021] On the other hand, if the Mg content in the core material is excessively high, the liquid phase ratio of the core material during brazing is likely to be high. Therefore, in this case, the strength of the core material may be excessively reduced during brazing, making the clad plate more susceptible to deformation. Furthermore, if the Mg content in the core material is high, the Mg in the core material may diffuse due to heating during brazing, causing an increase in the Mg concentration on the surface of the clad material. The Mg on the surface of the clad material may react with the flux used in brazing to form a high-melting-point compound. Furthermore, if the amount of Mg-flux compound formed on the surface of the clad material is excessively high, brazing properties may be deteriorated. By setting the Mg content in the core material to 2.0 mass% or less, preferably 1.9 mass% or less, and more preferably 1.8 mass% or less, an excessive increase in the Mg concentration on the surface of the clad material can be suppressed, and these problems can be easily avoided.

[0022] Furthermore, if the ratio of the Mg content to the Si content, Mg / Si, is excessively high, MgSi is likely to grow excessively in the core material after brazing, and the strength-improving effect of MgSi is likely to decrease. By setting the ratio of the Mg content to the Si content, Mg / Si, to 12 or less, preferably 10 or less, more preferably 8 or less, even more preferably 7 or less, and particularly preferably 6 or less, this problem can be easily avoided.

[0023] The preferred range of the Mg content in the core material can be determined by any combination of the upper and lower limits of the Mg content described above. For example, the preferred range of the Mg content in the core material may be 1.3% by mass to 2.0% by mass, 1.4% by mass to 2.0% by mass, 1.4% by mass to 1.9% by mass, or 1.4% by mass to 1.8% by mass.

[0024] Fe: 0% by mass or more and 0.40% by mass or less The core material may contain 0.40% by mass or less of Fe as an optional component. If the Fe content in the core material is excessively high, coarse crystals containing Fe are likely to form during casting of the core material, which may result in reduced workability. By setting the Fe content in the core material to preferably 0.40% by mass or less, more preferably 0.35% by mass or less, this problem can be more easily avoided.

[0025] Cu: 0% by mass or more and 0.20% by mass or less The core material may contain 0.20% by mass or less of Cu as an optional component. Cu in the core material dissolves in the Al matrix and has the effect of improving the strength of the core material through solid solution strengthening. On the other hand, if the Cu content in the core material is excessively high, it may lead to an increase in the liquid phase ratio of the core material during brazing. By setting the Cu content in the core material to preferably 0.20% by mass or less, more preferably 0.10% by mass or less, it is possible to further improve the strength of the core material while avoiding an excessive increase in the liquid phase ratio of the core material during brazing.

[0026] Mn: 0% by mass or more and 0.30% by mass or less The core material may contain 0.30% by mass or less of Mn as an optional component. If the Mn content in the core material is excessively high, Al-Mn-Si compounds are more likely to form in the core material. If excessive Al-Mn-Si compounds are formed in the core material, the effect of improving the strength of the core material due to the precipitation of MgSi may be reduced. By setting the Mn content in the core material to preferably 0.30% by mass or less, such problems can be more easily avoided.

[0027] Cr: 0% by mass or more and 0.10% by mass or less The core material may contain 0.10% by mass or less of Cr as an optional component. If the Cr content in the core material is excessively high, coarse intermetallic compounds containing Cr are likely to form in the core material, which may result in a decrease in hot workability. By setting the Cr content in the core material to preferably 0.10% by mass or less, more preferably 0.05% by mass or less, and even more preferably 0.03% by mass or less, this problem can be more easily avoided.

[0028] Zn: 0% by mass or more and 0.50% by mass or less The core material may contain 0.50% by mass or less of Zn as an optional component. By setting the Zn content in the core material to preferably 0.50% by mass or less, more preferably 0.40% by mass or less, and even more preferably 0.30% by mass or less, the natural electrode potential of the core material can be easily adjusted within an appropriate range. As a result, the corrosion resistance of the structure can be more easily improved.

[0029] Ti: 0% by mass or more and 0.10% by mass or less The core material may contain 0.10% by mass or less of Ti as an optional component. Ti has the effect of refining the ingot structure and improving the corrosion resistance of the core material. From the viewpoint of more reliably obtaining these effects, the Ti content in the core material is preferably 0.01% by mass or more. On the other hand, if the Ti content in the core material is excessively high, coarse crystals are likely to form in the ingot, which may result in a decrease in hot workability. By setting the Ti content in the core material to preferably 0.10% by mass or less, the above-mentioned effects can be obtained while more easily avoiding a decrease in hot workability.

[0030] Liquid phase ratio at 610°C The liquid phase ratio of the core material at a temperature of 610°C is less than 4.4 mass%. By making the liquid phase ratio of the core material at 610°C less than 4.4 mass%, excessive melting of the core material during brazing can be avoided, and the shape of the clad plate can be easily maintained. From the viewpoint of more reliably obtaining this effect, the liquid phase ratio of the core material at a temperature of 610°C is preferably less than 3.5 mass%, more preferably less than 3.0 mass%, even more preferably less than 2.5 mass%, particularly preferably less than 2.0 mass%, and most preferably less than 1.0 mass%.

[0031] The liquid fraction of the core material at 610°C varies mainly depending on the chemical composition of the core material. For example, Si, Mg, Cu, and Zn have the effect of lowering the solidus temperature of the core material and increasing the liquid fraction of the core material at 610°C. Therefore, by reducing the content of these elements, the liquid fraction of the core material at 610°C can be reduced. Thermodynamic calculation software (e.g., "JMatPro (registered trademark)" manufactured by Sente Software, Inc.) can be used to calculate the liquid fraction of the core material at 610°C.

[0032] Tensile Strength of Core Material: The core material preferably has a tensile strength of 220 MPa or greater when the clad plate is heated at an average heating rate of 10°C / min to 100°C / min to a holding temperature of 100±1°C to 600±10°C, held at the holding temperature for 3±2 minutes, cooled from the holding temperature to 100°C at an average cooling rate of 100°C / min to 150°C / min, and then held at a temperature of 25±5°C for 120 hours or greater. Core materials with such characteristics can easily precipitate fine MgSi particles by natural aging after brazing. Therefore, clad plates containing such core materials can more easily improve their strength after brazing.

[0033] Furthermore, the core material preferably has a tensile strength of 250 MPa or greater when the clad plate is heated from 100±1°C to a holding temperature of 600±10°C at an average heating rate of 10°C / min to 100°C / min, held at the holding temperature for 3±2 minutes, cooled from the holding temperature to 100°C at an average cooling rate of 100°C / min to 150°C / min, and then held at a temperature of 230±5°C for 20±5 minutes. A core material with such characteristics can easily precipitate fine MgSi particles by further artificial aging after brazing. Therefore, a clad plate having such a core material can more easily improve its strength after brazing.

[0034] The tensile strength of the core material in a clad plate can be obtained, for example, as follows. First, a single-layer test material made of an aluminum alloy having the same chemical composition as the core material of the clad plate is prepared. This test material is heat-treated under the conditions described above, and then a tensile test is performed using a method conforming to JIS Z2241:2011. The tensile strength of the test material thus obtained, which simulates the core material, can be used as the tensile strength of the core material in the clad plate.

[0035] In addition, when the tensile strengths of the layers other than the core material constituting the clad plate are known, the tensile strength of the core material can also be calculated based on the tensile strength of the clad plate after the above-mentioned heat treatment and the clad ratio. That is, the tensile strength TS (unit: MPa) of the clad plate is calculated by multiplying the tensile strength σ of the i-th layer of the layers constituting the core material by i (unit: MPa), and the thickness t of the i-th layer i (unit: μm) and the thickness t of the clad plate (unit: μm), it is expressed by the following formula (1).

[0036]

[0037] Therefore, for example, when a clad plate has a two-layer structure consisting of a core material and a skin material laminated on one side of the core material, the tensile strength TS (unit: MPa) of the clad plate, the thickness t (unit: μm) of the clad plate, and the thickness t of the core material are c (unit: μm), tensile strength of skin material σ s (unit: MPa) and thickness of skin material t s (unit: μm) and the tensile strength σ of the core material was calculated based on the following formula (2): c (unit: MPa) can be calculated. c = (TS t-σ s ・t s ) / t c ...(2)

[0038] [Skin Material] The skin material of the clad plate has a solidus temperature of 610°C or higher. By setting the solidus temperature of the skin material to 610°C or higher, deformation of the clad plate during brazing can be suppressed. Furthermore, by setting the solidus temperature of the skin material to 610°C or higher, erosion of the skin material by the brazing material is less likely to occur. As a result, the occurrence of local melting of the clad plate, known as erosion, can be suppressed. If the solidus temperature of the skin material is lower than 610°C, the clad plate may be more likely to melt locally during brazing and may be more likely to deform.

[0039] The solidus temperature of the cladding material varies mainly depending on the chemical composition of the cladding material. For example, Si, Mg, Cu, and Zn have the effect of lowering the solidus temperature of the cladding material. Therefore, the solidus temperature of the cladding material can be controlled by adjusting the content of these elements. Thermodynamic calculation software (e.g., "JMatPro (registered trademark)" manufactured by Sente Software, Inc.) can be used to calculate the solidus temperature of the cladding material.

[0040] The Mg content in the coating material is 0.10 mass% or less. When a flux is used for brazing an aluminum alloy, the Mg in the aluminum alloy reacts with the flux, and a high-melting-point compound may be formed on the surface of the aluminum alloy. If a large amount of this compound is formed on the surface of the aluminum alloy, the flux is prevented from destroying the natural oxide film, making it difficult to form a brazed joint.

[0041] In contrast, the Mg content in the clad plate is 0.10 mass% or less. By setting the Mg content in the clad plate to 0.10 mass% or less, the amount of compounds of Mg and flux formed on the surface of the clad plate can be reduced even when brazing is performed using flux. As a result, it is possible to avoid a decrease in the brazability of the clad plate and to increase the strength of the clad plate after brazing. From the viewpoint of more reliably obtaining such effects, it is preferable that the Mg content in the clad plate be 0.05 mass% or less.

[0042] The skin material may be made of aluminum or an aluminum alloy. Examples of aluminum that makes up the skin material include 1000-series aluminum having a Mg content within the above-mentioned specific range. Examples of aluminum alloys that make up the skin material include 3000-series aluminum alloys and 7000-series aluminum alloys having a Mg content within the above-mentioned specific range.

[0043] From the viewpoint of further increasing the strength of the clad plate, the skin material is preferably made of a 3000 series aluminum alloy or a 7000 series aluminum alloy, and more preferably made of a 3000 series aluminum alloy.

[0044] Furthermore, the tensile strength of the skin material is preferably 85 MPa or more. By setting the tensile strength of the skin material within the above-mentioned specific range, the difference in strength between the skin material and the core material can be sufficiently reduced, making it easier to hot-roll the clad plate. As a result, the clad plate can be more easily manufactured.

[0045] The thickness of the skin material per side is preferably 50 μm or more. By setting the thickness of the skin material within the above-mentioned specific range, the amount of Mg that diffuses from the core material to the surface of the brazing filler metal during brazing can be further reduced, and an excessive increase in the Mg concentration on the surface of the skin material can be easily prevented. As a result, it is possible to more easily prevent a decrease in the brazeability of the clad plate due to compounds of flux and Mg.

[0046] The clad ratio of the skin material per side, i.e., the ratio of the thickness of the skin material per side to the thickness of the clad plate, is preferably 5% or more and 30% or less. By setting the clad ratio of the skin material within the above-mentioned specific range, the effect of suppressing deformation of the clad plate during brazing can be more reliably obtained, and the strength of the clad plate can be more easily increased.

[0047] [Thickness of Clad Plate] The thickness of the clad plate is preferably 0.5 mm or more and 2.0 mm or less. By setting the thickness of the clad plate within the above specific range, the strength of the clad plate can be more easily increased.

[0048] [Uses of Clad Plate] As described above, the clad plate can suppress deformation of a structure during brazing and has high strength after brazing. From the viewpoint of effectively utilizing these properties, the clad plate is preferably used in applications in which a skin material and a mating material are joined by brazing. That is, the clad plate is preferably used as an aluminum member in an aluminum alloy structure in which one or more aluminum members are joined via brazing.

[0049] (Method for manufacturing clad plate) A known method can be used to manufacture the clad plate. For example, the method for manufacturing the clad plate may include a lamination step of manufacturing a clad ingot by laminating a plurality of aluminum ingots, each of which includes a core ingot having the chemical components of the core material and a cladding ingot having the chemical components of the cladding material, and a hot rolling step of manufacturing the clad plate by hot rolling the clad ingot.

[0050] The method for producing the aluminum ingots used in the lamination step is not particularly limited, and various casting methods such as semi-continuous casting, continuous casting, etc. After casting, these aluminum ingots may be laminated without being subjected to heat treatment, or may be laminated after being subjected to heat treatment such as homogenization treatment as necessary.

[0051] In the lamination step, the aluminum blocks are stacked in a desired order to produce a clad block. The stacking order and number of layers of the aluminum blocks in the clad block may be appropriately determined depending on the desired laminate structure and number of layers of the clad plate.

[0052] For example, to obtain a two-layer clad plate having a core and a skin layer laminated on one side of the core, a two-layer clad ingot consisting of a core ingot and a skin layer laminated on one side of the core ingot can be prepared. Similarly, to obtain a three-layer clad plate having a core and a skin layer laminated on both sides of the core, a three-layer clad ingot consisting of a core ingot and a skin layer laminated on both sides of the core ingot can be prepared.

[0053] After the lamination step, a hot rolling step is performed in which the clad ingot is hot rolled. By hot rolling the clad ingot in the hot rolling step, adjacent aluminum blocks are bonded to each other, thereby obtaining the clad plate. The hot rolling start temperature in the hot rolling step can be appropriately set, for example, within the range of 400°C or higher and 550°C or lower. Furthermore, after the hot rolling step, the clad plate may be heated and subjected to a homogenization treatment, if necessary.

[0054] After the hot rolling step, a cold rolling step may be performed, if necessary, in which the clad plate is subjected to cold rolling. By performing cold rolling on the clad plate, the thickness of the clad plate can be adjusted. The rolling conditions in the cold rolling step may be appropriately set depending on the desired thickness of the clad plate, etc. Furthermore, before, during, or after cold rolling, the clad plate may be heated and annealed, if necessary.

[0055] (Aluminum alloy structure) By joining one or more aluminum members including the aluminum alloy clad plate by brazing, an aluminum alloy structure (hereinafter referred to as "structure") can be obtained. In the structure including the clad plate, it is preferable that the skin material of the clad plate and a mating material are joined via brazing.

[0056] As described above, the clad plate has a skin material whose Mg content is within the specified range. Therefore, by joining the skin material and the mating material by brazing, a sound brazed joint can be easily formed between the skin material and the mating material, and erosion due to the corrosion of the brazing filler metal can be easily avoided. Furthermore, since the solidus temperature of the skin material is within the specified range, deformation of the clad plate during brazing can be suppressed. As a result, a structure having a desired shape can be easily obtained.

[0057] Furthermore, since the core material has the specific chemical composition, the strength of the core material can be increased by natural aging or artificial aging after brazing is completed, which makes it easy to increase the rigidity of the structure.

[0058] The structure may be composed of only the clad plate. In this case, the structure can be obtained by, for example, joining the skin materials of the clad plate together via brazing. Furthermore, the structure may include an aluminum member made of aluminum or an aluminum alloy in addition to the clad plate. In this case, the structure can be obtained by joining the skin material of the clad plate and the aluminum member via brazing.

[0059] The brazing method between the clad plate and the mating material is not particularly limited, and known methods can be appropriately employed. For example, when brazing the clad plate and the mating material, a brazing paste material containing Si powder and flux powder can be placed between the skin material of the clad plate and the mating material, and then heating can be employed. In this case, a brazing filler metal is generated between the skin material and the mating material by heating, and the natural oxide films present on the surfaces of the skin material and the mating material are destroyed by the flux, thereby forming a brazed joint between the skin material and the mating material. Alternatively, a brazing filler metal composed of an Al-Si alloy or the like and flux can be placed between the skin material of the clad plate and the mating material, and then heating can be employed. In this case, the brazing filler metal is melted by heating, forming a brazing filler metal between the skin material and the mating material, and the natural oxide films present on the surfaces of the skin material and the mating material are destroyed by the flux, thereby forming a brazed joint between the skin material and the mating material. Furthermore, a brazing sheet having a core material and a brazing material provided on at least one side of the core material can be used as the mating material, and the brazing sheet can be brazed to the skin material of the clad plate by melting the brazing material of the brazing sheet.

[0060] (Vehicle Cooling Device) The structure can be suitably used as a vehicle cooling device or a component thereof. As described above, the structure has high rigidity as a result of the strength of the core material being increased by natural aging or artificial aging after brazing. Therefore, by using the structure as a vehicle cooling device or a component thereof, it is possible to easily reduce the weight of the vehicle cooling device while ensuring the rigidity required for the vehicle cooling device.

[0061] The specific configuration of the vehicle cooler including the structure can take various forms. For example, the vehicle cooler may have a cooling section through which a cooling medium flows, a refrigerant inlet section that introduces the cooling medium into the cooling section, and a refrigerant outlet section that discharges the cooling medium in the cooling section to the outside of the cooler. In this case, for example, the object to be cooled can be cooled by bringing the object into contact with the surface of the cooling section. Examples of the object to be cooled include a secondary battery.

[0062] The structure may constitute a part of or the entire vehicle cooler. From the viewpoint of more easily reducing the weight of the vehicle cooler, it is preferable that the cooling portion of the vehicle cooler is constituted by the structure, and it is more preferable that the entire vehicle cooler is constituted by the structure.

[0063] (Example) An example of the aluminum alloy clad plate will be described below with reference to Figure 1. As shown in Figure 1, the clad plate 1 of this example includes a core material 2 and a skin material 3 provided on at least one side of the core material 2. The core material 2 has a chemical composition including Si: 0.10 to 0.40% by mass, Fe: 0 to 0.40% by mass, Cu: 0 to 0.20% by mass, Mn: 0 to 0.30% by mass, Mg: 1.2 to 2.0% by mass, Cr: 0 to 0.10% by mass, Zn: 0 to 0.50% by mass, and Ti: 0 to 0.10% by mass, with the balance being Al and unavoidable impurities. The ratio of Mg to Si (Mg / Si) is 12 or less. The liquid phase fraction of the core material 2 at 610°C is less than 4.4% by mass. The cladding material 3 is made of aluminum or an aluminum alloy. The solidus temperature of the cladding material 3 is 610° C. or higher. The Mg content in the cladding material 3 is 0.10 mass % or less.

[0064] 1, the clad plate 1 of this example has a three-layer structure consisting of a core material 2 and skin materials 3 laminated on both sides of the core material 2. The thickness of the clad plate 1 is, for example, 1.0 mm, and the thickness of the skin materials 3 per side is, for example, 150 μm. Therefore, the clad ratio of the skin materials 3 per side calculated based on these thicknesses is 15%.

[0065] The core material 2 has a chemical composition containing, for example, 0.29 mass% Si, 0.24 mass% Fe, 0.09 mass% Cu, 0.15 mass% Mn, 1.5 mass% Mg, 0.30 mass% Zn, and 0.01 mass% Ti, with the remainder being Al. The liquid phase fraction of the core material 2 having such a chemical composition at 610°C is 0.3 mass%. The liquid phase fraction of the core material 2 at 610°C is a value calculated using thermodynamic calculation software (specifically, "JMatPro" manufactured by Sente Software).

[0066] The skin material 3 may be made of an aluminum alloy having a chemical composition represented by alloy number A3003, for example. The solidus temperature of such an aluminum alloy is approximately 640° C. The solidus temperature of the skin material 3 is a value calculated by thermodynamic calculation software (specifically, “JMatPro” manufactured by Sente Software).

[0067] In manufacturing the clad plate 1 of this example, first, a core ingot having the chemical components of the core material 2 and a cladding ingot having the chemical components of the cladding material 3 are produced by semi-continuous casting. These aluminum ingots are subjected to rolling and homogenization treatment as necessary, and then the cladding ingots are layered on both sides of the core ingot to produce a cladding ingot.

[0068] Next, the clad ingot is hot-rolled to bond the core ingot and the skin ingot together to produce the clad plate 1. The clad plate 1 thus obtained is then cold-rolled to reduce the thickness of the clad plate 1 to 1.0 mm. In this manner, the clad plate 1 of this example can be obtained.

[0069] The core material 2 in the clad plate 1 of this example has the above-mentioned specific chemical composition. Therefore, by performing brazing using the clad plate 1 of this example, fine MgSi can be precipitated in the core material 2 after brazing is completed. As a result, the strength of the clad plate 1 after brazing can be improved.

[0070] In addition, a skin material 3 is provided on at least one surface of the core material 2. The skin material 3 has a solidus temperature within a specific range, which can suppress deformation of the clad plate 1 during brazing. Therefore, by using the clad plate 1, deformation of the structure during brazing can be suppressed. Furthermore, by setting the Mg content in the skin material 3 within the specific range, a brazed joint can be easily formed between the skin material 3 and the mating material.

[0071] (Experimental Example) In this example, an example of evaluating the shape retention during brazing of the core material in the clad plate of Example 1 and the strength after brazing is described. In this example, first, an aluminum ingot having the chemical composition shown in Test Material A1 in Table 1 is produced by semi-continuous casting. Next, the aluminum ingot is cut to produce a plate material with a thickness of 30 mm. This plate material is subjected to homogenization treatment by holding it at a temperature of 560°C for 6 hours, and then hot-rolled without cooling to a thickness of 3 mm. The plate material is then cold-rolled to a thickness of 0.8 mm. The cold-rolled plate material is subjected to final annealing by holding it at a temperature of 400°C for 1 hour. Through the above steps, Test Material A1 simulating the core material of the clad plate of Example 1 can be obtained. Test Material A2 shown in Table 1 has the same composition as Test Material A1, except for its chemical composition. The method for producing test material A2 was the same as the method for producing test material A1, except that the chemical composition of the aluminum block was changed as shown in Table 1.

[0072] Note that test materials B1 to B5 shown in Table 1 are test materials for comparison with test materials A1 and A2. Test materials B1 to B5 are made of aluminum alloys having the chemical compositions shown in Table 1. The manufacturing method for test materials B1 to B5 is the same as the manufacturing method for test material A1, except that the chemical composition of the aluminum block is changed as shown in Table 1. Also, "Bal." in Table 1 is a symbol indicating the remainder.

[0073] Table 2 shows the liquid phase ratio of the test material at 610°C, the amount of sagging in the sag test, the tensile strength of the test material simulating the core material after brazing and natural aging, and the tensile strength of the test material simulating the core material after brazing and artificial aging. The liquid phase ratios shown in Table 2 are values ​​calculated using thermodynamic calculation software (specifically, "JMatPro" manufactured by Sente Software).

[0074] The sag test method and the method for measuring the amount of sagging are as follows. First, each test material is cut to obtain a test piece S having a length of 130 mm. The base end S1 in the longitudinal direction of this test piece S is placed on the sample stage 41 of the testing device 4 shown in FIG. 2. Then, with the tip end S2 in the longitudinal direction of the test piece S protruding horizontally from the sample stage 41, the base end S1 is fixed by a fixture 42. The length L of the tip end S2 of the test piece S, i.e., the portion protruding from the sample stage 41, is set to 100 mm.

[0075] Next, the test piece S attached to the test device 4 is heated from 100±1°C to a holding temperature of 610±5°C at an average heating rate of 40°C / min, and after holding at this holding temperature for 4 minutes, is cooled to room temperature, thereby performing a heat treatment simulating brazing. After cooling is completed, the sagging amount h of the test piece S, i.e., the length in the vertical direction from the position of the tip S21 of the test piece S before heating to the position of the tip S21' of the test piece S after heating, is measured.

[0076] The tensile strength of the test material was measured as follows. First, the test material was heated from 100±1°C to a holding temperature of 600±10°C at an average heating rate of 34°C / min, and after holding at this holding temperature for 5 minutes, the test material was cooled from the holding temperature to 100°C at an average cooling rate of 138°C / min, thereby performing a heat treatment simulating brazing. The test material was then held at a temperature of 25±5°C for 144 hours, thereby performing natural aging. This procedure allows for the production of a test material simulating the core material after brazing and natural aging.

[0077] In addition to the above test material, a heat treatment simulating brazing was also performed by heating a test material from 100±1°C to a holding temperature of 600±10°C at an average heating rate of 36°C / min, holding the holding temperature for 5 minutes, and then cooling the test material from the holding temperature to 100°C at an average cooling rate of 145°C / min. This test material was held at a temperature of 25±5°C for 72 hours, and then artificially aged at a temperature of 230°C for 20 minutes. This process allows for the production of a test material simulating the core material after brazing and artificial aging.

[0078] The test materials thus obtained are subjected to a tensile test in accordance with JIS Z2241:2011. Table 2 shows the tensile strength of each test material obtained by the tensile test. Note that the symbol "-" is entered in the tensile strength column for test materials that have not been subjected to a tensile test.

[0079]

[0080]

[0081] As shown in Table 1, test materials A1 and A2 have the specific chemical compositions. Furthermore, as shown in Table 2, the liquid phase ratios of test materials A1 and A2 at 610°C are within the specific ranges. Therefore, test materials A1 and A2 exhibit high strength when subjected to heating simulating brazing, followed by natural aging or artificial aging.

[0082] In contrast, the Mg content of test material B1 is lower than the specific range, and therefore the tensile strength of test material B1 after natural aging and after artificial aging is lower than that of test material A1.

[0083] The Si content of test materials B2 to B4 is higher than the specific range. Therefore, the liquid phase fraction of these test materials at 610°C is higher than the specific range. Clad plates using such test materials as core materials are prone to deformation during brazing, which may make it difficult to obtain a structure with the desired shape.

[0084] Although the chemical composition of Test Material B5 is within the specific range, the liquid phase ratio of Test Material B5 at 610° C. is higher than the specific range. Therefore, a clad plate using Test Material B5 as a core material is likely to deform during brazing, and it may be difficult to obtain a structure having a desired shape.

[0085] The above has explained the aspects of the aluminum alloy clad plate based on the examples and experimental examples, but the specific aspects of the aluminum alloy clad plate, aluminum alloy structure, and automotive cooler according to the present invention are not limited to the aspects of the examples and experimental examples, and the configurations can be changed as appropriate within the scope that does not impair the intent of the present invention.

[0086] For example, the aluminum alloy clad plate can take the following forms [1] to [9].

[0087] [1] An aluminum alloy clad plate comprising: a core material having a chemical composition containing Si: 0.10% by mass or more and 0.40% by mass or less, Fe: 0% by mass or more and 0.40% by mass or less, Cu: 0% by mass or more and 0.20% by mass or less, Mn: 0% by mass or more and 0.30% by mass or less, Mg: 1.2% by mass or more and 2.0% by mass or less, Cr: 0% by mass or more and 0.10% by mass or less, Zn: 0% by mass or more and 0.50% by mass or less, and Ti: 0% by mass or more and 0.10% by mass or less, with the balance being Al and unavoidable impurities, and having a liquid phase fraction at 610°C of less than 4.4% by mass; and a skin material made of aluminum or an aluminum alloy and provided on at least one side of the core material, wherein the solidus temperature of the skin material is 610°C or more, and the Mg content of the skin material is 0.10% by mass or less.

[0088] [2] The aluminum alloy clad plate according to [1], wherein the skin material is composed of 1000 series aluminum, 3000 series aluminum alloy, or 7000 series aluminum alloy. [3] The aluminum alloy clad plate according to [1] or [2], wherein the skin material has a tensile strength of 85 MPa or more. [4] The aluminum alloy clad plate according to any one of [1] to [3], wherein the skin material has a thickness of 50 μm or more per side. [5] The aluminum alloy clad plate according to any one of [1] to [4], wherein the skin material has a cladding ratio of 5% or more and 30% or less per side.

[0089] [6] The aluminum alloy clad plate according to any one of [1] to [5], wherein the thickness of the clad plate is 0.5 mm or more and 2.0 mm or less. [7] The aluminum alloy clad plate according to any one of [1] to [6], wherein the core material has a property that the tensile strength is 220 MPa or more when the clad plate is subjected to a treatment that comprises heating the clad plate from 100±1°C to a holding temperature of 600±10°C at an average heating rate of 10°C / min to 100°C / min, holding the holding temperature for 3±2 minutes, and then cooling the clad plate from the holding temperature to 100°C at an average cooling rate of 100°C / min to 150°C / min, and then holding the clad plate at a temperature of 25±5°C for 120 hours or more.

[0090] [8] The aluminum alloy clad plate according to any one of [1] to [7], wherein the core material has a property of having a tensile strength of 250 MPa or more when subjected to a treatment that comprises heating the clad plate from 100±1°C to a holding temperature of 600±10°C at an average heating rate of 10°C / min to 100°C / min, holding the holding temperature for 3±2 minutes, and then cooling the clad plate from the holding temperature to 100°C at an average cooling rate of 100°C / min to 150°C / min, and then holding the clad plate at a temperature of 230±5°C for 20±5 minutes. [9] The aluminum alloy clad plate according to any one of [1] to [8], which is used for joining the skin material and a mating material by brazing.

[0091] The aluminum alloy structure may also take the form of the following item

[10] :

[10] An aluminum alloy structure including the aluminum alloy clad plate according to any one of items [1] to [9], wherein the skin material of the clad plate and a mating material are joined via brazing.

[0092] The vehicle cooler may have the following configuration according to

[11] :

[11] A vehicle cooler including the aluminum alloy structure according to

[10] .

Claims

1. An aluminum alloy clad plate comprising: a core material having a chemical composition containing Si: 0.10% by mass or more and 0.40% by mass or less, Fe: 0% by mass or more and 0.40% by mass or less, Cu: 0% by mass or more and 0.20% by mass or less, Mn: 0% by mass or more and 0.30% by mass or less, Mg: 1.2% by mass or more and 2.0% by mass or less, Cr: 0% by mass or more and 0.10% by mass or less, Zn: 0% by mass or more and 0.50% by mass or less, and Ti: 0% by mass or more and 0.10% by mass or less, with the balance being Al and unavoidable impurities, wherein the ratio of the Mg content to the Si content, Mg / Si, is 12 or less, and the liquid phase fraction at 610°C is less than 4.4% by mass; and a skin material made of aluminum or an aluminum alloy and provided on at least one side of the core material, wherein the solidus temperature of the skin material is 610°C or more, and the Mg content of the skin material is 0.10% by mass or less.

2. The aluminum alloy clad plate according to claim 1, wherein the skin material is made of 1000 series aluminum, 3000 series aluminum alloy, or 7000 series aluminum alloy.

3. The aluminum alloy clad plate according to claim 1, wherein the tensile strength of the skin material is 85 MPa or more.

4. The aluminum alloy clad plate according to claim 1, wherein the thickness of the skin material per side is 50 μm or more.

5. The aluminum alloy clad plate according to claim 1, wherein the clad ratio per side of the skin material is 5% or more and 30% or less.

6. The aluminum alloy clad plate according to claim 1, wherein the thickness of the clad plate is 0.5 mm or more and 2.0 mm or less.

7. An aluminum alloy clad plate according to claim 1, wherein the core material has a characteristic such that the tensile strength is 220 MPa or more when the clad plate is subjected to a treatment comprising heating the clad plate from 100±1°C to a holding temperature of 600±10°C at an average heating rate of 10°C / min to 100°C / min, holding the holding temperature for 3±2 minutes, and then cooling the clad plate from the holding temperature to 100°C at an average cooling rate of 100°C / min to 150°C / min, and then holding the clad plate at a temperature of 25±5°C for 120 hours or more.

8. An aluminum alloy clad plate according to claim 1, wherein the core material has a characteristic such that the tensile strength is 250 MPa or more when the clad plate is subjected to a treatment comprising heating the clad plate from 100±1°C to a holding temperature of 600±10°C at an average heating rate of 10°C / min to 100°C / min, holding the holding temperature for 3±2 minutes, and then cooling the clad plate from the holding temperature to 100°C at an average cooling rate of 100°C / min to 150°C / min, and then holding the clad plate at a temperature of 230±5°C for 20±5 minutes.

9. The aluminum alloy clad plate according to claim 1, which is used in applications where the skin material and a mating material are joined by brazing.

10. An aluminum alloy structure comprising an aluminum alloy clad plate according to any one of claims 1 to 9, wherein the skin material of the clad plate and a mating material are joined via brazing.

11. A vehicle cooler comprising the aluminum alloy structure according to claim 10.

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