Aluminum alloy brazing sheet and manufacturing method thereof

Abstract

To provide a brazing sheet that can exhibit exceptional brazing performance when an aluminum material is brazed without using flux in an inert gas atmosphere such as a nitrogen gas atmosphere.SOLUTION: The present invention provides an aluminum alloy brazing sheet used in brazing within an inert gas atmosphere, the aluminum alloy brazing sheet having a core material and a brazing material with which one or both surfaces of the core material are clad, the core material being formed from an aluminum alloy that contains 0.10-0.50 mass% of Mg, the balance being aluminum and unavoidable impurities, the brazing material being formed from an aluminum alloy that contains 6.00-13.00 mass% of Si and is limited to less than 0.05 mass% of Mg, the balance being aluminum and unavoidable impurities, and the Mg integration value from the surface of the brazing material to a depth of 30 nm therefrom being 150 atm%×nm or less.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an aluminum alloy brazing sheet and a method for producing the same. [Background technology]

[0002] Aluminum products such as aluminum heat exchangers and machine parts have many parts made of aluminum material (including aluminum and aluminum alloys; the same applies below). The aluminum products have many fine joints, and brazing is widely used as a joining method for forming such joints. Many of these aluminum products are brazed using a so-called brazing sheet, which is an aluminum material having a core material and a brazing material provided on at least one surface of the core material.

[0003] Brazing aluminum materials (including aluminum alloy materials) requires a method for destroying the oxide film covering the surface of the brazing material by bringing the molten brazing material into contact with the mating material to be joined while destroying the oxide film covering the surface of the mating material. Such methods, broadly classified into a method using flux (flux brazing method) and a method using heating in a vacuum (vacuum brazing method), have been put into practical use.

[0004] Among these methods, the flux brazing method is a method in which flux is applied to the surfaces of the parts to be joined, that is, the parts to be joined by brazing, and then brazing is performed. However, the flux brazing method requires the application of flux before brazing and the subsequent removal of the flux and its residue after brazing, which increases the manufacturing costs of aluminum products. Furthermore, if the flux and its residue are not sufficiently removed after brazing, sufficient surface quality may not be obtained when subsequent surface treatments are performed.

[0005] On the other hand, vacuum brazing is a method in which brazing is performed in a vacuum without applying flux to the surfaces of the parts to be joined. However, vacuum brazing has lower productivity than flux brazing, making it difficult to obtain sufficient brazing quality, and the brazing furnace used in vacuum brazing is likely to require higher equipment and maintenance costs than a general brazing furnace.

[0006] Therefore, a so-called flux-free brazing method has been proposed, in which brazing is performed in an inert gas atmosphere without applying flux to the surfaces of the parts to be joined. The brazing sheets used in the flux-free brazing method contain an element in at least one layer of the laminated structure that has the effect of weakening or destroying the oxide film, and Mg is often used as this type of element.

[0007] However, Mg is relatively easily oxidized, and the Mg on the surface of the brazing material reacts with oxygen that enters from the outside, easily forming an MgO film. This MgO film is much stronger than an Al2O3 film, so a brazing sheet with a thick MgO film formed on it does not exhibit good brazing properties because the MgO film is not destroyed during brazing, making it difficult for the molten brazing filler to wet and spread over the surface. That is, even if the thickness of the Al2O3 film on the surface of the brazing sheet is thin, if the MgO film is thick, brazing defects are likely to occur.

[0008] Under these circumstances, Patent Document 1 proposes an aluminum alloy brazing sheet to be used for brazing in an inert gas atmosphere without using flux, which comprises a core material made of aluminum or an aluminum alloy and a brazing filler metal made of an aluminum alloy containing 4.0 to 13.0 mass % of Si clad on one or both sides of the core material, and in which, upon brazing heating, oxide particles containing X atoms are formed on the surface, the volume change rate of which is 0.99 or less relative to the oxide film before brazing heating.

[0009] Patent Document 2 discloses a fluxless brazing method for aluminum materials, which uses a brazing sheet in which an Al-Si-Mg brazing filler metal containing, by mass, 5.0 to 13.0% Si and 0.1 to 3.0% Mg is clad on a core material and located on the outermost surface, and in which the average thickness of an oxide film on the surface of the Al-Si-Mg brazing filler metal before brazing is 150 Å or less and the average thickness of a magnesium oxide film in the oxide film is 20 Å or less, and which brings the Al-Si-Mg brazing filler metal on the brazing sheet into close contact with workpieces to be brazed in a non-oxidizing atmosphere with an oxygen concentration of 50 ppm or less without reducing pressure, and brazes and joins the core material and the workpieces to be brazed with the Al-Si-Mg brazing filler metal at the contacted portion without flux. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] Japanese Patent Application Publication No. 2019-069474 [Patent Document 2] Japanese Patent Application Laid-Open No. 2013-215797 Summary of the Invention [Problem to be solved by the invention]

[0011] However, after investigations by the present inventors, it was found that the brazing sheet described in Patent Document 1 is unable to adequately destroy the oxide film on the surface of the brazing filler metal when it becomes thick, and as a result, the molten brazing filler metal does not wet and spread sufficiently on the surface, and as a result, the desired new surface cannot be exposed, and poor brazing is likely to occur. Patent Document 1 also describes that the oxide film on the surface of the brazing filler metal becomes more susceptible to destruction when its thickness is set to 30 nm or less. However, since the ease with which the oxide film is destroyed varies depending on the elements that make up the oxide film, simply controlling the thickness of the oxide film is not necessarily sufficient to prevent the occurrence of brazing defects.

[0012] Furthermore, the inventors have conducted research and found that, although the brazing sheet described in Patent Document 2 has a thin MgO coating before brazing heating, the brazing material contains Mg, and therefore an MgO coating is formed and grows during brazing heating. In other words, it was found that the brazing sheet described in Patent Document 2 has a thick oxide film already formed when the brazing filler metal is melted, and therefore the oxide film is not destroyed, preventing the molten brazing filler metal from spreading over the surface, resulting in a decrease in brazing properties.

[0013] Under these circumstances, the present invention aims to provide a brazing sheet that can exhibit excellent brazing properties when brazing aluminum materials without using flux in an inert gas atmosphere such as a nitrogen gas atmosphere, and a method for manufacturing the same. [Means for solving the problem]

[0014] As a result of intensive research by the present inventors to solve the above technical problems, they have found that the above technical problems can be solved by an aluminum alloy brazing sheet used for brazing in an inert gas atmosphere, which comprises a core material and a brazing filler metal clad on one or both sides of the core material, wherein the core material is made of an aluminum alloy containing 0.10 to 0.50 mass% Mg, the balance being aluminum and unavoidable impurities, and the brazing filler metal contains 6.00 to 13.00 mass% Si, with a Mg content limited to less than 0.05 mass%, the balance being aluminum and unavoidable impurities, and wherein the Mg integrated value up to a depth of 30 nm from the brazing filler metal surface is 150 atm% × nm or less, and they have completed the present invention based on this finding.

[0015] That is, the present invention is (1) An aluminum alloy brazing sheet used for brazing in an inert gas atmosphere or in a vacuum, A core material and a brazing material clad on one or both sides of the core material, the core material is made of an aluminum alloy containing 0.10 to 0.50 mass% of Mg, with the remainder being aluminum and unavoidable impurities; The brazing filler metal is made of an aluminum alloy containing 6.00 to 13.00 mass% of Si, with a Mg content limited to less than 0.05 mass%, with the remainder being aluminum and unavoidable impurities; The Mg integral value from the surface of the brazing material to a depth of 30 nm is 150 atm% × nm or less An aluminum alloy brazing sheet, (2) The aluminum alloy brazing sheet according to (1) above, wherein the brazing filler metal further contains 1.00 mass % or less of Bi. (3) The aluminum alloy brazing sheet according to (1) or (2) above, characterized in that the core material further contains one or more of 0.70 mass% or less of Fe, 0.70 mass% or less of Si, 1.60 mass% or less of Mn, and 0.50 mass% or less of Cu. (4) The aluminum alloy brazing sheet according to any one of (1) to (3) above, wherein the core material further contains 3.00 mass% or less of Zn. (5) The aluminum alloy brazing sheet according to any one of (1) to (4) above, characterized in that the surface is etched with an acid. (6) A method for producing the aluminum alloy brazing sheet according to any one of (1) to (5) above, In producing an aluminum alloy brazing sheet, a laminate of a core ingot and a brazing filler ingot stacked on one or both sides of the core ingot is subjected to at least hot working, cold working, and one or more annealing treatments selected from one or more intermediate annealings between rolling passes in the cold working, and a final annealing after the last cold working pass, Heating during one or more annealing treatments selected from intermediate annealing between passes of the cold rolling and final annealing after the last cold working pass is performed by a method according to the following formula (I): D=ΣD0·exp(-Q / (RTn))·Δtn (I) (In the formula, Tn is the heating temperature (K) at each short time interval Δtn (seconds) when the total heating time (seconds) in the intermediate annealing and final annealing is divided into short times, and D0 = 1.24 × 10 -4 (m 2 / s), Q = 130 (kJ / mol), R = 8.3145 (J / (mol K)). The value of the diffusion amount D expressed as 7.0 × 10 -10 m 2 So that it becomes A method for producing an aluminum alloy brazing sheet, (7) The method for producing an aluminum alloy brazing sheet according to (6) above, characterized in that the intermediate annealing or final annealing is carried out in a state where the brazing filler metal ingot is rolled to a thickness of 10 μm to 50 μm. This provides: [Effects of the Invention]

[0016] According to the present invention, a brazing sheet having excellent brazing properties and a method for manufacturing the same can be provided when brazing aluminum materials in an inert gas atmosphere such as a nitrogen gas atmosphere without using flux. [Brief explanation of the drawings]

[0017] [Figure 1] FIG. 1(a) is a diagram showing the relationship between the Mg concentration and the distance (μm) from the surface of the brazing filler metal constituting the aluminum alloy brazing sheet, and FIG. 1(b) is a partially enlarged view of the part indicated by the dashed line in FIG. 1(a). [Figure 2] FIG. 1 is a schematic explanatory view of a mini-core test specimen prepared in the examples and comparative examples of the present application. DETAILED DESCRIPTION OF THE INVENTION

[0018] The aluminum alloy brazing sheet according to the present invention is an aluminum alloy brazing sheet used for brazing in an inert gas atmosphere, A core material and a brazing material clad on one or both sides of the core material, the core material is made of an aluminum alloy containing 0.10 to 0.50 mass% of Mg, with the remainder being aluminum and unavoidable impurities; The brazing filler metal is made of an aluminum alloy containing 6.00 to 13.00 mass% of Si, with a Mg content limited to less than 0.05 mass%, with the remainder being aluminum and unavoidable impurities; The Mg integral value from the surface of the brazing material to a depth of 30 nm is 150 atm% × nm or less It is characterized by the following.

[0019] First, the aluminum alloy brazing sheet according to the present invention will be described. The aluminum alloy brazing sheet according to the present invention comprises a core material and a brazing filler metal clad on one side (either main surface) or both sides (both main surfaces) of the core material.

[0020] In the aluminum alloy brazing sheet according to the present invention, the core material is made of an aluminum alloy containing 0.10 to 0.50 mass % of Mg, with the remainder being aluminum and unavoidable impurities.

[0021] In the aluminum alloy brazing sheet according to the present invention, the core material contains Mg. The Mg contained in the core material gradually diffuses into the brazing filler metal during brazing heating, and upon the start of melting of the brazing filler metal (specifically, partial melting of the Al-Si-Mg ternary eutectic), the Mg rapidly diffuses toward the brazing filler metal surface, easily weakening and destroying the aluminum oxide film covering the surface of the brazing filler metal. Since most of the Mg is supplied from the core material rather than the brazing filler metal, the aluminum oxide film covering the surface of the brazing filler metal can be easily weakened while suppressing the formation of MgO on the surface of the brazing filler metal. Furthermore, Mg dissolves in the matrix and improves the strength of the material through solid solution strengthening. The Mg content in the core wood is 0.10 to 0.50 mass %, preferably 0.10 to 0.45 mass %, and more preferably 0.15 to 0.40 mass %. By ensuring that the Mg content in the core material is within the above range, a sufficient amount of Mg can diffuse and dissolve into the brazing material, weakening the aluminum oxide film on the surface of the brazing material, while also preventing a decrease in the solidus temperature (melting point) of the core material, thereby preventing the core material from melting during brazing.

[0022] In the aluminum alloy brazing sheet according to the present invention, the core material may contain Fe. When the core material contains Fe, the Fe content in the core material is preferably 0.70 mass % or less, more preferably 0.05 to 0.50 mass %, and even more preferably 0.10 to 0.40 mass %. By keeping the Fe content in the core material at 0.70 mass% or less, it is possible to easily suppress a decrease in corrosion resistance and the occurrence of coarse crystals, while easily achieving the desired strength improvement effect by forming intermetallic compounds with other metal elements.

[0023] In the aluminum alloy brazing sheet according to the present invention, the core material may contain Si. When the core material contains Si, the Si content in the core material is preferably 0.70 mass % or less, more preferably 0.10 to 0.65 mass %, and even more preferably 0.20 to 0.60 mass %. By keeping the Si content in the core material within the above range, local melting due to a decrease in the melting point of the core material can be easily suppressed, while the strength of the core material can be easily improved through solid solution strengthening and fine precipitation strengthening of intermetallic compounds.

[0024] In the aluminum alloy brazing sheet according to the present invention, the core material may contain Mn. When the core material contains Mn, the Mn content in the core material is preferably 1.60 mass % or less, more preferably 0.40 to 1.60 mass %, and even more preferably 0.60 to 1.50 mass %. By ensuring that the Mn content in the core material is within the above range, it is possible to easily suppress the deterioration of rolling workability due to the generation of coarse crystals during casting, while easily improving the strength of the core material and easily improving its corrosion resistance by adjusting the potential of the core material.

[0025] In the aluminum alloy brazing sheet according to the present invention, the core material may contain Cu. When the core material contains Cu, the Cu content in the core material is preferably 0.50% by mass or less, more preferably 0.05 to 0.45% by mass, and even more preferably 0.10 to 0.40% by mass. By keeping the Cu content in the core material within the above range, local melting due to a decrease in the melting point of the core material is suppressed, and the strength of the core material is easily improved, while the potential of the core material can be adjusted to easily improve its corrosion resistance.

[0026] In the aluminum alloy brazing sheet according to the present invention, the core material may contain Zn. When the core material contains Zn, the Zn content in the core material is preferably 3.00 mass % or less, more preferably 0.50 to 2.50 mass %, and even more preferably 1.00 to 2.00 mass %. When the Zn content in the core material is within the above range, the self-potential of the core material becomes baser, and the core material can easily function as a sacrificial anode for a long period of time.

[0027] In the aluminum alloy brazing sheet according to the present invention, the core material may contain Ti. When the core material contains Ti, the Ti content in the core material is preferably 0.20 mass % or less, more preferably 0.05 to 0.20 mass %, and even more preferably 0.05 to 0.18 mass %. When the content of Ti in the core material is within the above range, corrosion of the core material progresses in layers, and the progress of corrosion in the depth direction can be easily suppressed.

[0028] In the aluminum alloy brazing sheet according to the present invention, the core material may contain Zr. When the core material contains Zr, the Zr content in the core material is preferably 0.50% by mass or less, more preferably 0.05 to 0.30% by mass, and even more preferably 0.10 to 0.20% by mass. When the Zr content in the core material is within the above range, corrosion of the core material progresses in layers, and the progress of corrosion in the depth direction can be easily suppressed.

[0029] In the aluminum alloy brazing sheet according to the present invention, the core material may contain Cr. When the core material contains Cr, the Cr content in the core material is preferably 0.50% by mass or less, more preferably 0.05 to 0.30% by mass, and even more preferably 0.10 to 0.20% by mass. By ensuring that the Cr content in the core material is within the above range, corrosion of the core material progresses in layers, making it possible to easily suppress the progression of corrosion in the depth direction. In the aluminum alloy brazing sheet according to the present invention, the core material may contain V. When the core material contains V, the V content in the core material is preferably 0.50% by mass or less, more preferably 0.05 to 0.30% by mass, and even more preferably 0.10 to 0.20% by mass. By ensuring that the V content in the core material is within the above range, corrosion of the core material progresses in layers, making it possible to easily suppress the progression of corrosion in the depth direction.

[0030] In this application, the content of each component constituting the core material means the value measured by an emission spectrometer.

[0031] In the aluminum alloy brazing sheet according to the present invention, one or both sides of the core material are clad with a brazing filler metal, and the brazing filler metal is made of an aluminum alloy containing 6.00 to 13.00 mass% Si, with the Mg content limited to less than 0.05 mass%, and the remainder being aluminum and unavoidable impurities.

[0032] In the aluminum alloy brazing sheet according to the present invention, the brazing filler metal contains Si. The Si contained in the brazing material lowers the melting point of Al and increases its fluidity, allowing the brazing material to function. The Si content in the brazing filler metal is 6.00 to 13.00 mass %, preferably 6.70 to 12.80 mass %, and more preferably 9.00 to 12.50 mass %. When the Si content in the brazing filler metal is within the above range, sufficient fluidity can be exhibited and erosion of the core material or other parts to be joined can be suppressed.

[0033] In the aluminum alloy brazing sheet according to the present invention, the Mg content in the brazing filler metal is limited to less than 0.05 mass %. The Mg contained in the brazing filler metal can easily weaken and destroy the aluminum oxide film that covers the surface of the brazing filler metal during brazing heating. However, in this application document, the Mg content in the brazing filler metal is limited in order to suppress the formation of an MgO film on the surface of the brazing filler metal. The Mg content in the brazing filler metal is less than 0.05 mass % (not less than 0.00 mass % and less than 0.05 mass %), preferably 0.00 to 0.04 mass %, and more preferably 0.00 to 0.02 mass %. By ensuring that the Mg content in the brazing filler metal is less than 0.05% by mass, the generation of MgO on the brazing filler metal surface is suppressed, while a sufficient amount of Mg diffuses and dissolves from the core material into the brazing filler metal during brazing, weakening the aluminum oxide film on the brazing filler metal surface.

[0034] In the aluminum alloy brazing sheet according to the present invention, the brazing filler metal may contain Bi. The Bi content in the brazing filler metal is preferably 1.00 mass% or less, more preferably 0.005 to 1.00 mass%, even more preferably 0.01 to 0.40 mass%, even more preferably 0.010 to 0.20 mass%, and even more preferably 0.01 to 0.10 mass%. wax Material By ensuring that the Bi content is within the above range, the surface tension of the braze can be reduced, and the fluidity of the braze can be easily increased.

[0035] In the aluminum alloy brazing sheet according to the present invention, the brazing filler metal may contain one or two elements selected from Sr and Na. The Sr content in the brazing filler metal is preferably 0.100% by mass or less, more preferably 0.070% by mass or less, and even more preferably 0.050% by mass or less. Although there is no particular lower limit for the Sr content in the brazing filler metal, it is preferably 0.003 mass % or more. The Na content in the brazing filler metal is preferably 0.300% by mass or less, more preferably 0.200% by mass or less, and even more preferably 0.100% by mass or less. Although there is no particular lower limit for the Na content in the brazing filler metal, it is preferably 0.002 mass % or more.

[0036] By ensuring that the Sr and Na contents are each within the above ranges, the structure of the solidified brazing filler metal can be made finer in the joint formed after brazing, and the joint strength can be suitably improved.

[0037] The total content of Sr and Na contained in the brazing filler metal is preferably 0.002 to 0.600 mass%, more preferably 0.003 to 0.400 mass%, and even more preferably 0.005 to 0.200 mass%.

[0038] In this application, the content of each component constituting the brazing material can be measured by an emission spectrometer.

[0039] In the aluminum alloy brazing sheet according to the present invention, the Mg integral value from the surface of the brazing filler metal to a depth of 30 nm is 150 atm% × nm or less, preferably 110 atm% × nm or less, and more preferably 70 atm% × nm or less. In the aluminum alloy brazing sheet according to the present invention, the Mg integral value from the surface of the brazing filler metal to a depth of 30 nm is 150 atm% × nm or less, so that the thickness of the MgO film on the surface of the brazing filler metal is controlled to a predetermined thickness, and this MgO film is easily destroyed during brazing, allowing the molten brazing filler metal to wet and spread over the surface, making it easy to obtain good brazing properties.

[0040] In this application, the Mg integral value from the brazing filler metal surface to a depth of 30 nm refers to the integrated value of the Mg concentration up to a depth of 30 nm when the brazing filler metal surface is sputtered with argon ions using an X-ray photoelectron spectrometer (XPS) and the Mg concentration is measured every 1 nm. The Mg concentration at each 1 nm depth is determined from the sputtering rate (sputtering depth / sputtering time) and sputtering time during the XPS measurement. The sputtering rate (sputtering depth / sputtering time) is calculated based on the time it takes for the measured O concentration to reach 0 when the O concentration is measured while sputtering a SiO thin film with a known thickness.

[0041] According to the inventors' investigations, the process of formation and growth of the MgO film during brazing heating was thoroughly investigated, and as a result, the following findings were obtained. In other words, when a brazing sheet clad with a brazing filler metal having a limited Mg content is heated and brazed to a core material containing a predetermined amount of Mg, the Mg diffuses from the core material to the brazing filler metal, and when it reaches the surface of the brazing filler metal from inside the brazing filler metal, it reacts with oxygen in the atmosphere to form MgO. As a result, the metallic Mg concentration in the vicinity of the brazing filler metal surface decreases, increasing the difference in metallic Mg concentration between the interior of the brazing filler metal and the surface, making it easier for metallic Mg in the interior of the brazing filler metal to migrate to the vicinity of the surface of the brazing filler metal. When metallic Mg reaches the surface of the brazing filler metal, it reacts with oxygen in the atmosphere to form MgO, forming a Mg-enriched layer in the very surface area, down to a depth of 30 nm from the brazing filler metal surface. FIG. 1(a) is a diagram showing the relationship between the Mg concentration and the distance (μm) from the surface of the brazing filler metal constituting the aluminum alloy brazing sheet, and FIG. 1(b) is a partially enlarged view of the part indicated by the dashed line in FIG. 1(a). As shown in Figure 1(a), even in the aluminum alloy brazing sheet in which the Mg content near the surface (the position at a distance of 0 μm from the material surface) is limited, as shown in Figure 1(b), a Mg-enriched layer with a high Mg concentration is formed in the very surface layer, down to a depth of 30 nm from the surface of the brazing material.

[0042] The inventors have discovered that by adopting an aluminum alloy brazing sheet in which a core material containing a predetermined amount of Mg is clad with a brazing filler metal having a limited Mg content, and in which the Mg integrated value in the Mg-enriched layer on the brazing filler metal surface is controlled in advance to a predetermined value or less, it is possible to easily weaken the aluminum oxide film and MgO film during brazing while controlling the thickness of the MgO film on the brazing filler metal surface during brazing, thereby enabling favorable brazing, and have completed the present invention.

[0043] The aluminum alloy brazing sheet according to the present invention comprises a core material and a brazing filler metal cladding one or both sides of the core material. The aluminum alloy brazing sheet according to the present invention may be in the form of (1) a two-layer material in which the brazing filler metal is clad on only one side of the core material (core material / brazing filler metal), (2) a three-layer material in which the brazing filler metal is clad on both sides of the core material (brazing filler metal / core material / brazing filler metal), or (3) a three-layer material in which the brazing filler metal is clad on one side of the core material and a sacrificial anode material is clad on the other side (brazing filler metal / core material / sacrificial anode material).

[0044] In the aluminum alloy brazing sheet according to the present invention, the cladding ratio of the brazing filler metal cladded on one or both sides of the core material (the ratio of the thickness of the brazing filler metal to the thickness of the aluminum alloy brazing sheet) is preferably 3 to 30%, more preferably 5 to 25%, and even more preferably 7 to 20%.

[0045] When the aluminum alloy brazing sheet according to the present invention takes the form of a three-layer material (2) in which a brazing material is clad on both sides of a core material, the composition and cladding ratio of the brazing material formed on each side of the core material may be the same or different.

[0046] When the aluminum alloy brazing sheet according to the present invention (3) takes the form of a three-layer material in which one side of a core material is clad with a brazing filler metal and the other side is clad with a sacrificial anode material, the sacrificial anode material is preferably made of aluminum or an aluminum alloy containing 8.00 mass% or less of Zn, the remainder being aluminum and unavoidable impurities.

[0047] The purity of the aluminum constituting the sacrificial anode material is not particularly limited, but is preferably 99.0 mass % or more, and more preferably 99.5 mass % or more.

[0048] The aluminum alloy for the sacrificial anode material preferably contains Zn, and the Zn contained in the sacrificial anode material has the effect of making the potential more base, and by creating a potential difference between the sacrificial anode material and the core material, it exhibits a sacrificial corrosion protection effect. The Zn content in the sacrificial anode material is preferably 8.00 mass% or less, more preferably 3.00 mass% or less.

[0049] In the aluminum alloy brazing sheet according to the present invention, the sacrificial anode material may contain Fe. When the sacrificial anode material contains Fe, the Fe content in the sacrificial anode material is preferably 1.00 mass % or less, more preferably 0.05 to 0.80 mass %, and even more preferably 0.100 to 0.700 mass %. When the Fe content in the sacrificial anode material is within the above range, the strength is easily improved, the deformation resistance during hot rolling is increased, and the difference in deformation resistance with the core material can be reduced.

[0050] In the aluminum alloy brazing sheet according to the present invention, the sacrificial anode material may contain Mn. When the sacrificial anode material contains Mn, the Mn content in the sacrificial anode material is preferably 1.80 mass % or less, more preferably 0.10 to 1.50 mass %, and even more preferably 0.20 to 1.20 mass %. By ensuring that the Mn content in the sacrificial anode material is within the above range, it is possible to adjust the size of the crystal grains of the sacrificial anode material that are formed by recrystallization during brazing.

[0051] In the aluminum alloy brazing sheet according to the present invention, the sacrificial anode material may contain Mg. When the sacrificial anode material contains Mg, the Mg content in the sacrificial anode material is preferably 1.00 mass % or less, more preferably 0.05 to 1.00 mass %, and even more preferably 0.10 to 0.80 mass %. When the Mg content in the sacrificial anode material is within the above range, the strength of the sacrificial anode material can be easily increased.

[0052] In the present application, the content of each component constituting the sacrificial anode material means a value measured by an optical emission spectrometer (XPS).

[0053] In the aluminum alloy brazing sheet according to the present invention, the cladding ratio of the sacrificial anode material (the ratio of the thickness of the sacrificial anode material to the thickness of the aluminum alloy brazing sheet) is preferably 3 to 30%, more preferably 5 to 25%, and even more preferably 7 to 20%.

[0054] The aluminum alloy brazing sheet according to the present invention is used as a forming material for fins that serve as the heat transfer medium of heat exchangers, tubes that serve as flow path components through which refrigerants and the like pass, and plates that are joined to the tubes to form the structure of the heat exchanger. When the aluminum alloy brazing sheet according to the present invention is used for a fin material, the thickness of the brazing sheet is preferably about 0.04 to 0.20 mm. When the aluminum alloy brazing sheet according to the present invention is used for a tube material, the thickness of the brazing sheet is preferably about 0.15 to 0.50 mm. When the aluminum alloy brazing sheet according to the present invention is used for a plate material, the thickness of the brazing sheet is preferably about 0.80 to 5.00 mm.

[0055] The aluminum alloy brazing sheet according to the present invention may be one in which the surface of the brazing filler metal has been subjected to an etching treatment with an acid. By the above etching, the aluminum oxide film or MgO film formed on the surface can be weakened or removed in advance. The etching process will be described in detail later.

[0056] According to the present invention, a brazing sheet having excellent brazing properties can be provided when brazing aluminum materials in an inert gas atmosphere such as a nitrogen gas atmosphere without using a flux.

[0057] Next, a method for producing an aluminum alloy brazing sheet according to the present invention will be described. The manufacturing method according to the present invention is a method for manufacturing the aluminum alloy brazing sheet according to the present invention, In producing an aluminum alloy brazing sheet, a laminate of a core ingot and a brazing filler ingot stacked on one or both sides of the core ingot is subjected to at least hot working, cold working, and one or more annealing treatments selected from one or more intermediate annealings between rolling passes in the cold working, and a final annealing after the last cold working pass, Heating during one or more annealing treatments selected from intermediate annealing between passes of the cold rolling and final annealing after the last cold working pass is performed by a method according to the following formula (I): D=ΣD0·exp(-Q / (RTn))·Δtn (I) (In the formula, Tn is the heating temperature (K) at each short time interval Δtn (seconds) when the total heating time (seconds) in the intermediate annealing and final annealing is divided into short times, and D0 = 1.24 × 10 -4 (m 2 / s), Q = 130 (kJ / mol), R = 8.3145 (J / (mol K)). The value of the diffusion amount D expressed as 7.0 × 10 -10 m 2 So that it becomes This is characterized by carrying out the above steps.

[0058] In the method for manufacturing an aluminum alloy brazing sheet according to the present invention, first, aluminum alloys having the desired component compositions for the core material, brazing filler metal, and, if necessary, sacrificial anode material are melted and cast to produce an ingot for the core material, an ingot for the brazing filler metal, and, if necessary, an ingot for the sacrificial anode material. The melting and casting methods are not particularly limited, and conventional methods can be used.

[0059] Next, the core ingot, brazing filler ingot, and optionally the sacrificial anode ingot are preferably subjected to a homogenization treatment. The homogenization treatment is preferably carried out at a temperature of 400 to 600°C for a period of 2 to 20 hours.

[0060] Next, the core ingot, brazing ingot, and optionally the sacrificial anode ingot are machined or hot rolled to a predetermined thickness, and then the predetermined ingots are stacked in a predetermined order to form a laminate.

[0061] The above-mentioned core material ingot, brazing material ingot and, if necessary, sacrificial anode material ingot each have a composition corresponding to the composition of the core material, brazing material and sacrificial anode material that constitute the aluminum alloy brazing sheet to be obtained.

[0062] In the method for producing an aluminum alloy brazing sheet according to the present invention, the laminate is subjected to one or more annealing treatments selected from at least one intermediate annealing treatment between hot working, cold working, and rolling passes in the cold working, and a final annealing treatment after the last cold working pass.

[0063] In the hot working, a laminate obtained by stacking predetermined ingots in a predetermined order is hot rolled at 400 to 500° C. In the hot rolling, rolling is carried out until the plate has a thickness of, for example, 2 to 8 mm.

[0064] In cold working, the hot-rolled product obtained by hot working is cold-rolled. In cold working, cold rolling is performed in multiple passes.

[0065] In cold working, one or more intermediate annealings between passes of cold rolling are preferably carried out at a heating temperature of 200 to 500°C, more preferably 250 to 400°C. In the intermediate annealing, the temperature may be raised to the intermediate annealing temperature, and cooling may be started immediately after the temperature is reached, or the temperature may be held at the intermediate annealing temperature for a certain period of time before cooling is started. The holding time at the intermediate annealing temperature is 0 to 10 hours, preferably 1 to 5 hours.

[0066] After cold rolling, the obtained cold rolled product is subjected to final annealing as appropriate. The final annealing is preferably carried out at a heating temperature of 300 to 500°C, more preferably 350 to 450°C. In the final annealing, the temperature may be raised to the final annealing temperature, and cooling may be started immediately after the final annealing temperature is reached, or the final annealing temperature may be held for a certain period of time after the temperature is reached, and then cooling may be started. The holding time at the final annealing temperature is 0 to 10 hours, preferably 1 to 5 hours.

[0067] The atmosphere during the intermediate annealing and final annealing is not particularly limited, but it is preferable to perform the annealing in an atmosphere with an oxygen concentration lower than that of the air. By heating in an atmosphere with an oxygen concentration lower than that of the air, the growth of an oxide film on the surface of the brazing filler metal can be suppressed.

[0068] In the method for producing an aluminum alloy brazing sheet according to the present invention, the intermediate annealing or final annealing is preferably performed on the brazing filler metal ingot after it has been rolled to a thickness of 10 μm to 50 μm, and more preferably after it has been rolled to a thickness of 20 μm to 50 μm.

[0069] By controlling the thickness of the brazing filler metal ingot during intermediate annealing or final annealing within the above range, the Mg concentration diffusing from the core ingot to the brazing filler metal ingot surface can be reduced, and the formation and growth of an MgO film can be suppressed, making it possible to easily exhibit desired brazing properties.

[0070] In the manufacturing method of the aluminum alloy brazing sheet according to the present invention, the heating in one or more annealing treatments selected from the intermediate annealing between passes of the cold rolling and the final annealing after the last cold working pass is carried out in accordance with the following formula (I): D=ΣD0·exp(-Q / (RTn))·Δtn (I) (In the formula, Tn is the heating temperature (K) at each short time interval Δtn (seconds) when the total heating time (seconds) in the intermediate annealing and final annealing is divided into short times, and D0 = 1.24 × 10 -4 (m 2 / s), Q = 130 (kJ / mol), R = 8.3145 (J / (mol K)). The value of the diffusion amount D expressed as 7.0 × 10 -10 m 2 Do so as follows:

[0071] In the manufacturing method of the aluminum alloy brazing sheet according to the present invention, the intermediate annealing between the cold rolling passes and the final annealing after the last cold working pass are performed in such a manner that the value of the diffusion amount D is 7.0 × 10 -10 m 2 Do the following: 5.0 x 10 -10 m 2 It is preferable to do so as follows: 2.0 × 10 -10 m 2 It is more preferable to carry out the following: The lower limit of the diffusion amount D is not particularly limited, but the diffusion amount D is usually 1.0 × 10 -16 m 2 That's all. The intermediate annealing between the cold rolling passes and the final annealing after the last cold working pass were performed under conditions where the value of the diffusion amount D was 7.0 × 10 -10 m 2 By carrying out the following steps, it is possible to limit the amount of Mg diffusing from the core ingot to the surface layer of the brazing filler ingot.

[0072] In the manufacturing method of the aluminum alloy brazing sheet according to the present invention, the Mg contained in the core material is diffused toward the surface layer of the brazing material by heating during the intermediate annealing between the passes of the cold rolling and the final annealing after the last pass of cold working. The amount of diffusion, D calculated by the formula (I), is 7.0 × 10 -10 m 2 This can be easily controlled by controlling the temperatures and times during intermediate annealing and final annealing as follows:

[0073] According to conventional methods, it is believed that an appropriate diffusion effect can be obtained by controlling the temperature finally reached by the heat treatment and the time for which that temperature is maintained. However, as described above, the aluminum alloy brazing sheet obtained by the manufacturing method according to the present invention is one in which the Mg integral value from the brazing filler metal surface to a depth of 30 nm is controlled to be 150 atm% × nm or less. In order to control the Mg integral value to an appropriate value, it is necessary to appropriately control the total amount of heat input in all processes during intermediate annealing and final annealing. To satisfy this requirement, the diffusion amount D calculated by the above formula (I) must be less than 7.0 × 10 -10 m 2 Less than 5.0 × 10 -10 m 2 Less than or equal to 2.0 × 10 -10 m 2 It is necessary to control it so that:

[0074] In the method for producing an aluminum alloy brazing sheet according to the present invention, the surface of the brazing sheet may be etched with an acid, if necessary. Etching treatment can weaken or remove aluminum oxide films and MgO films formed during heating during hot rolling, and heating between passes and after the final pass of cold rolling.

[0075] The timing of the etching treatment is not particularly limited as long as it is performed between the time of hot rolling and the time of brazing using a brazing sheet. For example, the etching treatment may be performed on a clad sheet after hot rolling, on a clad sheet during cold rolling, or after intermediate annealing or final annealing. Furthermore, after the above-mentioned final annealing is completed, the brazing sheet may be stored in a state in which it has an oxide film, and then subjected to an etching treatment immediately before brazing. If the oxide film is weakened or removed when brazing is performed, the brazing properties can be improved when brazing using a brazing sheet.

[0076] As described above, by carrying out the etching treatment, the MgO film formed on the surface of the brazing filler metal can be weakened or removed, that is, the Mg concentration on the surface of the brazing filler metal can be reduced. For example, in the case of thin materials such as fin stock used in automotive heat exchangers, the etching process may be performed before the annealing process due to equipment limitations. Even in such cases, the etching process has the effect of reducing the Mg concentration on the brazing filler metal surface, and by optimizing the processing conditions of the subsequent annealing process, the oxide film can be weakened and brazability can be easily improved.

[0077] The acid used in the etching treatment of the brazing sheet can be, for example, an aqueous solution of sulfuric acid, hydrochloric acid, nitric acid, phosphoric acid, hydrofluoric acid, or the like. These acids may be used alone or in combination of two or more. From the viewpoint of more efficiently removing the oxide film, it is preferable to use a mixed aqueous solution containing hydrofluoric acid and an acid other than hydrofluoric acid, and it is more preferable to use a mixed aqueous solution of hydrofluoric acid and sulfuric acid or a mixed aqueous solution of hydrofluoric acid and nitric acid.

[0078] The etching amount during etching is 0.05 to 2.00 g / m 2 The etching amount is preferably 0.05 g / m 2 More preferably, 0.10 g / m 2 By doing so, the oxide film on the surface of the brazing sheet can be sufficiently removed, and the brazing properties can be further improved. From the viewpoint of improving the brazing properties of the brazing sheet, there is no upper limit to the etching amount. However, if the etching amount is excessively large, it may become difficult to obtain the effect of improving the brazing properties commensurate with the processing time. 2 or less, more preferably 0.50 g / m 2 Such problems can be easily avoided by the following:

[0079] In the method for producing an aluminum alloy brazing sheet according to the present invention, an aluminum alloy brazing sheet can be obtained in this manner. The details of the obtained aluminum alloy brazing sheet are as described in detail in the description of the aluminum alloy brazing sheet according to the present invention.

[0080] According to the present invention, a brazing sheet with excellent brazing properties can be easily produced when brazing aluminum materials in an inert gas atmosphere such as a nitrogen gas atmosphere without using a flux.

[0081] The present invention will be specifically described below with reference to examples, but the present invention is not limited to the examples shown below. [Example]

[0082] Example 1 (1) Core ingots and a plurality of brazing filler ingots each having the chemical compositions shown in Table 1 were produced by continuous casting. Next, the core ingot was homogenized and then subjected to surface grinding to obtain a predetermined thickness. Next, a plurality of brazing filler metal ingots were each hot-rolled to obtain a predetermined thickness. The core ingot and multiple brazing filler ingots obtained in this manner were stacked in the order of brazing filler 1 ingot / core ingot / brazing filler 2 ingot, to obtain a three-layer laminate in which brazing filler 1 ingot and brazing filler 2 ingot were stacked on both sides of the core ingot. The resulting laminate was hot-rolled to join the core ingot and the brazing ingot together, thereby producing a clad material having a plate thickness of 2.6 mm. (2) The clad material obtained in (1) was subjected to cold rolling to obtain a cold-rolled product having a thickness of 0.17 mm. Next, the obtained cold rolled product was subjected to a test using a compound represented by the following formula (I): D=ΣD0·exp(-Q / (RTn))·Δtn (I) (In the formula, Tn is the heating temperature (K) at each short time interval Δtn (seconds) when the total heating time (seconds) in the intermediate annealing and final annealing is divided into short times, and D0 = 1.24 × 10 -4 (m 2 / s), Q = 130 (kJ / mol), R = 8.3145 (J / (mol K)). The value of the diffusion amount D expressed as 1.0 × 10 -10 m 2 The alloy was subjected to intermediate annealing in an air atmosphere while controlling the heating temperature and heating time so as to achieve the above-mentioned temperature. The resulting intermediate annealed material was subjected to cold rolling to obtain a test piece of aluminum alloy brazing sheet having a thickness of 0.10 mm, which had a three-layer structure of brazing material 1 / core material / brazing material 2, with the cladding ratios of the brazing materials on both sides of the core material being 12.6% (brazing material 1) and 11.3% (brazing material 2), respectively. The preparation conditions for the above test materials are shown in Table 3.

[0083] The integrated value of Mg from the surface of the brazing filler metal 1 of the obtained test material to a depth of 30 nm was measured using an X-ray photoelectron spectrometer (XPS, PHI 5000 VersaProbe III manufactured by ULVAC-PHI Co., Ltd.). The results are shown in Table 4. The thickness of the oxide film on the surface of the brazing filler metal 1 of the obtained test materials was measured by XPS (X-ray photoelectron spectroscopy). In this case, O (oxygen) was measured in the depth direction on the brazing filler metal surface of each test material, and the half-value width was taken as the thickness of the oxide film. The results are shown in Table 4.

[0084] <Brazability evaluation> Using the obtained test material, a mini-core test specimen simulating the core of a corrugated fin type heat exchanger was prepared by the following method, and brazability was evaluated based on the adhesion rate of the fins. In this evaluation, first, as shown in Figure 2, a mini-core test specimen was prepared, which had a corrugated fin 1 made of a brazing sheet having brazing material on both sides, made of the test material obtained in each of the above examples or comparative examples, and two flat plates 2, 2 that sandwiched the corrugated fin 1. Specifically, the obtained test material was cut to a predetermined size and then subjected to a corrugating process to obtain a corrugated fin 1-1 having a length of 35 mm, a height of 3 mm, and a apex pitch of 4.5 mm. Also, two flat plates 1-2 each having a length of 35 mm, a width of 30 mm and a thickness of 1.0 mm were obtained by cutting out a plate material of JIS A3003 alloy. The corrugated fin 1 and the two flat plates 2, 2 were degreased with acetone, and then the corrugated fin 1 was sandwiched between the two flat plates 2, 2 to prepare an assembly. The resulting assembly was heated to 600°C in an inert gas atmosphere under heating conditions such that it took 3 minutes to reach 400°C from 150°C and 5 minutes to reach 600°C from 400°C. The brazing material was then melted by maintaining the temperature at 600°C for 3 minutes, and the corrugated fin made of the core material was brazed to the flat plate in a brazing atmosphere with a dew point of -60°C and an oxygen concentration of 1 ppm. The corrugated fin 1 was cut out from the mini-core test piece after the heat treatment, and the joining rate was calculated based on the traces of the fillets present on the two flat plates 2, 2 by the following method. First, the length of the fillet traces present on each of the two flat plates 2, 2 in the width direction d of each flat plate 2 was measured, and the total length L1 was calculated. Separately, the total length L0 of each fillet in the width direction d of the flat plate 2 was calculated assuming that the two flat plates 2, 2 and the corrugated fin 1 were completely joined. The ratio of the value of length L1 to length L0 was then calculated as the joining rate (%). The length L0 can be calculated, for example, by multiplying the width of the corrugated fin 1 (the length in the width direction of the flat plate 2) by the number of apexes of the corrugated fin 1-2. However, in this example, in order to eliminate variations in the bonding rate due to assembly defects, the two ends in the width direction (two ends indicated by dashed lines in the example shown in Figure 2) were excluded from the calculation of the bonding rate.

[0085] Based on the obtained bonding rate, brazing was evaluated by determining that the brazing ability was good (◯) when the bonding rate was 60% or more, and determining that the brazing ability was poor (×) when the bonding rate was less than 60%. The results are shown in Table 4.

[0086] Example 2 The value of the diffusion amount D is 2.7 × 10 -10 m 2The same processing as in Example 1 was carried out, except that the heating temperature and heating time during intermediate annealing were controlled so as to obtain a test piece of an aluminum alloy brazing sheet having a thickness of 0.10 mm, which had a three-layer structure of brazing filler metal 1 / core material / brazing filler metal 2, and the cladding ratios of the brazing filler metals provided on both sides of the core material were 12.6% (brazing filler metal 1) and 11.3% (brazing filler metal 2), respectively. The obtained test material was evaluated in the same manner as in Example 1. The results are shown in Table 4.

[0087] Example 3 The value of the diffusion amount D is 6.7 × 10 -10 m 2 The same processing as in Example 1 was carried out, except that the heating temperature and heating time during intermediate annealing were controlled so as to obtain a test piece of an aluminum alloy brazing sheet having a thickness of 0.10 mm, which had a three-layer structure of brazing filler metal 1 / core material / brazing filler metal 2, and the cladding ratios of the brazing filler metals provided on both sides of the core material were 12.6% (brazing filler metal 1) and 11.3% (brazing filler metal 2), respectively. The obtained test material was evaluated in the same manner as in Example 1. The results are shown in Table 4.

[0088] (Comparative Example 1) The value of the diffusion amount D is 13.5 × 10 -10 m 2 The same processing as in Example 1 was carried out, except that the heating temperature and heating time during intermediate annealing were controlled so as to obtain a test piece of an aluminum alloy brazing sheet having a thickness of 0.10 mm, which had a three-layer structure of brazing filler metal 1 / core material / brazing filler metal 2, and the cladding ratios of the brazing filler metals provided on both sides of the core material were 12.6% (brazing filler metal 1) and 11.3% (brazing filler metal 2), respectively. The obtained test material was evaluated in the same manner as in Example 1. The results are shown in Table 4.

[0089] Example 4 (1) A clad material having a plate thickness of 2.6 mm was produced in the same manner as in Example 1(1). (2) The clad material obtained in (1) was cold-rolled to obtain a cold-rolled product with a thickness of 0.30 mm, and the obtained cold-rolled product was etched using an etching solution (containing 0.1% hydrofluoric acid and 1.0% sulfuric acid) at 70°C. The etched product was then further cold rolled to obtain a cold rolled product having a thickness of 0.17 mm. Thereafter, the obtained cold-rolled product was subjected to a process represented by the following formula (I): D=ΣD0·exp(-Q / (RTn))·Δtn (I) (In the formula, Tn is the heating temperature (K) at each short time interval Δtn (seconds) when the total heating time (seconds) in the intermediate annealing and final annealing is divided into short times, and D0 = 1.24 × 10 -4 (m 2 / s), Q = 130 (kJ / mol), R = 8.3145 (J / (mol K)). The value of the diffusion amount D expressed as 1.0 × 10 -10 m 2 In order to achieve this, intermediate annealing was performed in an atmosphere in which the oxygen concentration was controlled to 0.2% by volume or less, while controlling the heating temperature and heating time. The resulting intermediate annealed material was subjected to cold rolling to obtain a test piece of aluminum alloy brazing sheet having a thickness of 0.10 mm, which had a three-layer structure of brazing material 1 / core material / brazing material 2, with the cladding ratios of the brazing materials on both sides of the core material being 12.6% (brazing material 1) and 11.3% (brazing material 2), respectively. The obtained test material was evaluated in the same manner as in Example 1. The results are shown in Table 4.

[0090] Example 5 Using ingots for core material, ingots for brazing filler metal 1, and ingots for brazing filler metal 2, each having the chemical compositions shown in Table 2 and produced by continuous casting, the test pieces were processed in the same manner as in Example 1, except that the atmosphere during intermediate annealing was changed to an atmosphere in which the oxygen concentration was controlled to 0.2% by volume or less, to obtain test pieces of aluminum alloy brazing sheets having a thickness of 0.10 mm, each having a three-layer structure of brazing filler metal 1 / core material / brazing filler metal 2, and with cladding ratios of the brazing filler metals provided on both sides of the core material of 11.9% (brazing filler metal 1) and 12.1% (brazing filler metal 2), respectively. The obtained test material was evaluated in the same manner as in Example 1. The results are shown in Table 4.

[0091] [Table 1]

[0092] [Table 2]

[0093] [Table 3]

[0094] [Table 4]

[0095] From Table 4, it can be seen that the test materials of the aluminum alloy brazing sheets obtained in Examples 1 to 5 have a core material made of an aluminum alloy containing 0.10 to 0.50 mass% Mg, with the remainder being aluminum and unavoidable impurities, a brazing filler metal made of an aluminum alloy containing 6.00 to 13.00 mass% Si with a Mg content limited to less than 0.05 mass%, with the remainder being aluminum and unavoidable impurities, and the Mg integrated value from the brazing filler metal surface to a depth of 30 nm is 150 atm% × nm or less, so when brazing property evaluation was performed, all were rated as "Good", and all showed good brazing property (joinability).

[0096] On the other hand, as can be seen from Table 4, the test material of the aluminum alloy brazing sheet obtained in Comparative Example 1 had a high Mg integral value of 195 atm% × nm from the surface of the brazing filler metal to a depth of 30 nm, and was therefore rated as "×" when brazing performance was evaluated. ( It can be seen that the bonding strength is poor. [Industrial Applicability]

[0097] According to the present invention, a brazing sheet having excellent brazing properties and a method for manufacturing the same can be provided when brazing aluminum materials in an inert gas atmosphere such as a nitrogen gas atmosphere without using flux.

Claims

1. An aluminum alloy brazing sheet used for brazing in an inert gas atmosphere, A core material and a brazing material clad on one or both sides of the core material, the core material is made of an aluminum alloy containing 0.10 to 0.40 mass% Mg, 0.10 to 0.70 mass% Si, 0.05 to 0.70 mass% Fe, 0.05 to 0.50 mass% Cu, 0.40 to 1.60 mass% Mn, and 0.50 to 3.00 mass% Zn, with the remainder being aluminum and unavoidable impurities; the brazing filler metal is made of an aluminum alloy containing 6.00 to 13.00 mass% Si, 0.005 to 1.00 mass% Bi, with the Mg content limited to less than 0.05 mass%, and the remainder being aluminum and unavoidable impurities; An aluminum alloy brazing sheet characterized in that the Mg integrated value from the surface of the brazing material to a depth of 30 nm is 150 atm % × nm or less.

2. An aluminum alloy brazing sheet as described in claim 1, characterized in that it has an acid-etched surface.

3. A method for producing the aluminum alloy brazing sheet according to claim 1 or 2, comprising: In producing an aluminum alloy brazing sheet, a laminate of a core ingot and a brazing filler ingot stacked on one or both sides of the core ingot is subjected to at least one annealing treatment selected from hot working, cold working, and one or more intermediate annealing treatments between rolling passes in the cold working, and final annealing after the last cold working pass, Heating during one or more annealing treatments selected from intermediate annealing between passes of the cold rolling and final annealing after the last cold working pass is performed by a method represented by the following formula (I): D=ΣD ０ ・exp(-Q / (RTn))・Δtn (I) (Wherein, Tn is the heating temperature (K) at each minute time when the total heating time (seconds) in the intermediate annealing and final annealing is divided into minute times Δtn (seconds), and D ０ = 1.24 x 10 －４ (m ２ / s), Q = 130 (kJ / mol), R = 8.3145 (J / (mol·K)). The value of the diffusion amount D expressed as 7.0 × 10 －１０ m ２ A method for manufacturing an aluminum alloy brazing sheet, characterized by carrying out the following steps.

4. 4. The method for manufacturing an aluminum alloy brazing sheet according to claim 3, wherein the intermediate annealing or final annealing is performed in a state where the brazing filler metal ingot is rolled to a thickness of 10 μm to 50 μm.

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