Aluminum alloy brazing sheet

Abstract

To provide an aluminum alloy brazing sheet which has excellent brazing property in brazing in an inert gas atmosphere with non-use of flux.SOLUTION: In an aluminum alloy brazing sheet, a skin material 1, an inner brazing filler metal 1 and a core material are laminated in this order and are used for brazing in an inert gas atmosphere without use of flux, the inner brazing filler metal 1 which contains Si of 6.00 to 13.00 mass%, Mg more than 0.50 mass% to 4.50 mass% or less, and Bi of 0.010 to 0.50 mass%, and comprises an aluminum alloy comprising a balance aluminum and inevitable impurities. The skin material 1 contains Si of 6.00 to 13.00 mass%, Mg more than 0.050 mass% to 0.50 mass% or less, and Bi of 1.00 mass% or less, and comprises an aluminum alloy comprising a balance aluminum and inevitable impurities.SELECTED DRAWING: None

Description

Technical Field

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[0003]

[0001] The present invention relates to an aluminum alloy brazing sheet used for brazing in an inert gas atmosphere without using a flux.

Background Art

[0002] For aluminum heat exchangers and mechanical parts, a brazing technique capable of simultaneously brazing a large number of joints is widely used. Since aluminum has a very easy-to-oxidize property, it is immediately covered by a dense oxide film. Therefore, while having excellent corrosion resistance, the difficulty of joining is high. Thus, in aluminum brazing, suppression of the growth of the surface oxide film and its destruction are important, and there are roughly two practical methods: a method of heating in a vacuum without using a flux and a method of using a flux in a nitrogen gas atmosphere.

[0003] In the method of heating in a vacuum without using a flux, a brazing material made of an Al-Si-Mg-based alloy is used. By raising the temperature in a vacuum, the growth of the oxide film due to Al or Mg is prevented, and during brazing melting, the oxide film on the material surface is destroyed by the evaporation of Mg, enabling brazing. However, it has the disadvantage of requiring expensive vacuum heating equipment. Also, since the evaporated Mg adheres to the furnace, there is a problem that the maintenance cost for removing the adhered Mg is high.

[0004] On the other hand, in the method of using a flux in a nitrogen gas atmosphere, a brazing material made of an Al-Si-based alloy and a flux made of an Al-K-F-based are used. Even in a nitrogen gas atmosphere with a higher oxygen concentration compared to a vacuum, the molten flux prevents the growth of the oxide film on the surface of the brazing material while strongly destroying the oxide film, enabling brazing. This method does not require expensive vacuum heating equipment, but has problems such as the cost of the flux and the cost of the process of applying the flux increasing. Also, when the flux scatters into the working environment during application to the heat exchanger or evaporation during brazing, there are concerns about safety, hygiene, and environmental problems.

[0005] Therefore, there is a growing need for joining methods that do not use flux in an inert gas atmosphere.

[0006] To address these needs, for example, Patent Document 1 proposes that brazing of the bonding area becomes possible by incorporating Mg and Bi into the brazing material and treating it with an inorganic acid. Materials containing Mg in the brazing material cannot be brazed because MgO is formed during the heat treatment process in the material manufacturing process, but it is stated that brazing becomes possible by removing this MgO through treatment with an inorganic acid.

[0007] Furthermore, Patent Document 2 proposes that brazing is possible by regulating the amount of Mg in the brazing material and diffusing the Mg contained in the core material during brazing. An advantage of this method is that, since Mg is not present in the brazing material, the formation of MgO can be prevented during material manufacturing and during the brazing temperature increase.

[0008] On the other hand, Patent Document 3 proposes that by cladding an intermediate layer with a high Mg concentration between the brazing material and the core material, the supply of Mg to the brazing material can be increased without adding Mg to the brazing material, making it possible to destroy the oxide film to a certain extent efficiently. [Prior art documents] [Patent Documents]

[0009] [Patent Document 1] Japanese Patent Publication No. Hei 8-354934 [Patent Document 2] Japanese Patent Publication No. 2014-037576 [Patent Document 3] WO2016 / 056306 [Overview of the project] [Problems that the invention aims to solve]

[0010] However, as shown in Reference 1, MgO continues to grow even during the brazing heating process, resulting in a thick oxide film covering the material surface. This presents a problem in practical joints with large clearances, where sufficient fillets cannot be formed.

[0011] Furthermore, Reference 2 states that, due to constraints such as formability, there is a limit to the amount of Mg that can be added to the core material, and therefore, high-temperature, long-duration brazing heating is necessary to diffuse the Mg from the core material into the oxide film. Consequently, in a practical brazing atmosphere, high-temperature, long-duration brazing promotes the oxidation of the aluminum itself, causing the oxide film to grow thicker, which significantly reduces brazing performance.

[0012] Furthermore, Reference 3 fails to resolve the issue of uneven progression of oxide film destruction, and has not reached a practical level.

[0013] Therefore, the object of the present invention is to provide an aluminum alloy brazing sheet that has excellent brazing properties in brazing in an inert gas atmosphere without the use of flux. [Means for solving the problem]

[0014] The inventors of the present invention conducted extensive research to solve the above problems and discovered that by providing a brazing material (internal brazing material) containing predetermined amounts of Mg and Bi, and a protective layer containing a predetermined amount of Mg on the outside thereof, excellent brazing properties can be achieved in brazing in an inert gas atmosphere without the use of flux, thus completing the present invention.

[0015] In other words, the present invention (1) is an aluminum alloy brazing sheet that has a core made of pure aluminum or an aluminum alloy, and an internal brazing material 1 and a outer brazing material 1 clad on at least one side of the core in the order of outer brazing material 1 / internal brazing material 1 / core, and is used for brazing in an inert gas atmosphere without using flux. The internal brazing material 1 is made of an aluminum alloy containing 6.00 to 13.00 mass% Si, more than 0.50 mass% and 4.50 mass% or less Mg, and 0.010 to 0.50 mass% Bi, with the remainder being aluminum and unavoidable impurities. The aforementioned coating material 1 is an aluminum alloy containing 6.00 to 13.00 mass% of Si and more than 0.050 mass% and 0.50 mass% or less of Mg, with a Bi content of 1.00 mass% or less, and the remainder being aluminum and unavoidable impurities. This invention provides an aluminum alloy brazing sheet characterized by the following features.

[0016] Furthermore, the present invention (2) further comprises a sacrificial anode material A clad on the other side of the core material in the order of outer material 1 / internal brazing material 1 / core material / sacrificial anode material A, The sacrificial anode material A is an aluminum alloy containing one or more of the following: 5.00 mass% or less of Si, 1.50 mass% or less of Fe, 2.00 mass% or less of Cu, 2.00 mass% or less of Mn, 3.00 mass% or less of Mg, 6.00 mass% or less of Zn, 0.30 mass% or less of Cr, 0.30 mass% or less of Ti, and 0.30 mass% or less of Zr, with the remainder being aluminum and unavoidable impurities. The present invention provides an aluminum alloy brazing sheet characterized by (1).

[0017] Furthermore, the present invention (3) further comprises a layer material 1 / internal brazing material 1 / core material / outer brazing material, with the outer brazing material cladding to the other surface of the core material, The aforementioned outer brazing material contains 6.00 to 13.00 mass% of Si, and further contains one or more of the following: 1.00 mass% or less of Fe, 2.00 mass% or less of Cu, 2.00 mass% or less of Mn, 4.50 mass% or less of Mg, 6.00 mass% or less of Zn, 0.50 mass% or less of Bi, 0.30 mass% or less of Cr, 0.30 mass% or less of Ti, and 0.30 mass% or less of Zr, with the remainder being aluminum and unavoidable impurities, making it an aluminum alloy. It provides an aluminum alloy brazing sheet of (1) characterized by

[0018] Further, the present invention (4) further has a skin material 1 / internal brazing material 1 / core material / sacrificial anode material A / outer surface brazing material, and the outer surface brazing material is clad on the surface of the sacrificial anode material A opposite to the core material, The outer surface brazing material contains 6.00 to 13.00% by mass of Si, and further contains any one or more of Fe of 1.00% by mass or less, Cu of 2.00% by mass or less, Mn of 2.00% by mass or less, Mg of 4.50% by mass or less, Zn of 6.00% by mass or less, Bi of 0.50% by mass or less, Cr of 0.30% by mass or less, Ti of 0.30% by mass or less, and Zr of 0.30% by mass or less, and the balance is aluminum and inevitable impurities, and is made of an aluminum alloy, It provides an aluminum alloy brazing sheet of (2) characterized by

[0019] Further, the present invention (5) further has a skin material 1 / internal brazing material 1 / core material / sacrificial anode material A / internal brazing material 2 / skin material 2, and the internal brazing material 2 and the skin material 2 are clad on the surface of the sacrificial anode material A opposite to the core material, The internal brazing material 2 contains 6.00 to 13.00% by mass of Si, more than 0.50% and 4.50% by mass or less of Mg, and more than 0.010% and 0.50% by mass or less of Bi, and the balance is aluminum and inevitable impurities, and is made of an aluminum alloy, The skin material 2 contains 6.00 to 13.00% by mass of Si, more than 0.050% and 0.50% by mass or less of Mg, the Bi content is 1.00% by mass or less, and the balance is aluminum and inevitable impurities, and is made of an aluminum alloy, It provides an aluminum alloy brazing sheet of (2) characterized by

[0020] Further, the present invention (6) further has a skin material 1 / internal brazing material 1 / core material / internal brazing material 2 / skin material 2, and the internal brazing material 2 and the skin material 2 are clad on the other surface of the core material, The inner brazing material 2 is made of an aluminum alloy containing 6.00 to 13.00% by mass of Si, more than 0.50% by mass and 4.50% by mass or less of Mg, and 0.010 to 0.50% by mass of Bi, with the balance being aluminum and inevitable impurities. The skin material 2 contains 6.00 to 13.00% by mass of Si and more than 0.050% by mass and 0.50% by mass or less of Mg, has a Bi content of 1.00% by mass or less, and is made of an aluminum alloy consisting of the balance aluminum and inevitable impurities. It provides the aluminum alloy brazing sheet of (1) characterized by the above.

[0021] In addition, the present invention (7) is a sacrificial anode material B1, an inner brazing material 1, and a skin material clad in this order on at least one surface of a core material made of pure aluminum or an aluminum alloy, in the order of skin material 1 / inner brazing material 1 / sacrificial anode material B1 / core material. 1 It is an aluminum alloy brazing sheet that has the above and is used for brazing in an inert gas atmosphere without using a flux. The inner brazing material 1 contains 6.00 to 13.00% by mass of Si, more than 0.50% by mass and 4.50% by mass or less of Mg, and 0.010 to 0.50% by mass of Bi, and is made of an aluminum alloy consisting of the balance aluminum and inevitable impurities. The skin material 1 contains 6.00 to 13.00% by mass of Si and more than 0.050% by mass and 0.50% by mass or less of Mg, has a Bi content of 1.00% by mass or less, and is made of an aluminum alloy consisting of the balance aluminum and inevitable impurities. The sacrificial anode material B1 contains any one or more of 5.00% by mass or less of Si, 1.50% by mass or less of Fe,​​​

[0022] Furthermore, the present invention (8) further comprises a sacrificial anode material B2 clad on the other surface of the core material, in the order of skin material 1 / internal brazing material 1 / sacrificial anode material B1 / core material / sacrificial anode material B2. The sacrificial anode material B2 is an aluminum alloy containing one or more of the following: 5.00 mass% or less of Si, 1.50 mass% or less of Fe, 2.00 mass% or less of Cu, 2.00 mass% or less of Mn, 3.00 mass% or less of Mg, 6.00 mass% or less of Zn, 0.30 mass% or less of Cr, 0.30 mass% or less of Ti, and 0.30 mass% or less of Zr, with the remainder being aluminum and unavoidable impurities. The present invention provides an aluminum alloy brazing sheet (7) characterized by the following:

[0023] Furthermore, the present invention (9) further comprises a shell material 1 / internal brazing material 1 / sacrificial anode material B1 / core material / outer brazing material, with an outer brazing material cladding to the other surface of the core material, The aforementioned outer brazing material is an aluminum alloy containing 6.00 to 13.00 mass% Si, and further containing one or more of the following: 1.00 mass% or less Fe, 2.00 mass% or less Cu, 2.00 mass% or less Mn, 4.50 mass% or less Mg, 6.00 mass% or less Zn, 0.50 mass% or less Bi, 0.30 mass% or less Cr, 0.30 mass% or less Ti, and 0.30 mass% or less Zr, with the remainder being aluminum and unavoidable impurities. The present invention provides an aluminum alloy brazing sheet (7) characterized by the following:

[0024] Furthermore, the present invention (10) further comprises the sacrificial anode material in the order of skin material 1 / internal brazing material 1 / sacrificial anode material B1 / core material / sacrificial anode material B2 / outer brazing material B 2 has an outer brazing material clad to the side opposite to the core material, The aforementioned outer brazing material is an aluminum alloy containing 6.00 to 13.00 mass% Si, and further containing one or more of the following: 1.00 mass% or less Fe, 2.00 mass% or less Cu, 2.00 mass% or less Mn, 4.50 mass% or less Mg, 6.00 mass% or less Zn, 0.50 mass% or less Bi, 0.30 mass% or less Cr, 0.30 mass% or less Ti, and 0.30 mass% or less Zr, with the remainder being aluminum and unavoidable impurities. The present invention provides an aluminum alloy brazing sheet characterized by (8).

[0025] Furthermore, the present invention (11) further comprises the sacrificial anode material in the order of skin material 1 / internal brazing material 1 / sacrificial anode material B1 / core material / sacrificial anode material B2 / internal brazing material 2 / skin material 2 B The material 2 has an internal brazing material 2 and an outer layer 2 clad on the side opposite to the core material, The internal brazing material 2 is made of an aluminum alloy containing 6.00 to 13.00 mass% Si, more than 0.50 mass% and 4.50 mass% or less Mg, and 0.010 to 0.50 mass% Bi, with the remainder being aluminum and unavoidable impurities. The aforementioned outer material 2 is an aluminum alloy containing 6.00 to 13.00 mass% of Si and Mg exceeding 0.050 mass% and 0.50 mass% or less, with a Bi content of 1.00 mass% or less, and the remainder consisting of aluminum and unavoidable impurities. The present invention provides an aluminum alloy brazing sheet characterized by (8).

[0026] Furthermore, the present invention (12) further comprises an internal brazing material 2 and an internal brazing material 2 cladding to the other surface of the core material in the order of skin material 1 / internal brazing material 1 / sacrificial anode material B1 / core material / internal brazing material 2 / skin material 2, The internal brazing material 2 is made of an aluminum alloy containing 6.00 to 13.00 mass% Si, more than 0.50 mass% and 4.50 mass% or less Mg, and 0.010 to 0.50 mass% Bi, with the remainder being aluminum and unavoidable impurities. The aforementioned outer material 2 is an aluminum alloy containing 6.00 to 13.00 mass% of Si and Mg exceeding 0.050 mass% and 0.50 mass% or less, with a Bi content of 1.00 mass% or less, and the remainder consisting of aluminum and unavoidable impurities. The present invention provides an aluminum alloy brazing sheet (7) characterized by the following:

[0027] Furthermore, the present invention (13) provides an aluminum alloy brazing sheet according to any of (1) to (12), characterized in that the core material contains one or more of the following: 1.50% by mass or less of Si, 1.50% by mass or less of Fe, 2.00% by mass or less of Cu, 2.00% by mass or less of Mn, 3.00% by mass or less of Mg, 3.00% by mass or less of Zn, 0.50% by mass or less of Bi, 0.30% by mass or less of Cr, 0.30% by mass or less of Ti, and 0.30% by mass or less of Zr, with the remainder being aluminum and unavoidable impurities.

[0028] Furthermore, the present invention (14) provides an aluminum alloy brazing sheet according to any of (1) to (13), characterized in that the internal brazing material 1 or the internal brazing material 2 further contains one or more of the following: 1.00 mass% or less of Fe, 2.00 mass% or less of Cu, 2.00 mass% or less of Mn, 6.00 mass% or less of Zn, 0.30 mass% or less of Cr, 0.30 mass% or less of Ti, and 0.30 mass% or less of Zr.

[0029] Furthermore, the present invention (15) provides an aluminum alloy brazing sheet according to any of (1) to (14), characterized in that the skin material 1 or the skin material 2 further contains one or more of the following: 1.00 mass% or less of Fe, 2.00 mass% or less of Cu, 2.00 mass% or less of Mn, 6.00 mass% or less of Zn, 0.30 mass% or less of Cr, 0.30 mass% or less of Ti, and 0.30 mass% or less of Zr.

[0030] Furthermore, the present invention (16) provides an aluminum alloy brazing sheet according to any of (1) to (15), characterized in that the thickness of the leather material 1 or the leather material 2 is 5.0 μm or more.

[0031] Furthermore, the present invention (17) provides an aluminum alloy brazing sheet according to any of (1) to (16), characterized in that the thickness of the internal brazing material 1 or the internal brazing material 2 is 15.0 μm or more.

[0032] Furthermore, the present invention (18) provides an aluminum alloy brazing sheet according to any of (1) to (17), characterized in that the average Mg concentration in the thickness direction of the internal brazing material 1 and the outer material 1 exceeds 0.50% by mass, and the average Bi concentration in the thickness direction of the internal brazing material 1 and the outer material 1 exceeds 0.050% by mass.

[0033] Furthermore, the present invention (19) provides an aluminum alloy brazing sheet according to any of (1) to (18), characterized in that the average Mg concentration in the thickness direction of the internal brazing material 1 and the outer material 1 or the internal brazing material 2 and the outer material 2 exceeds 0.50% by mass, and the average Bi concentration in the thickness direction of the internal brazing material 1 and the outer material 1 or the internal brazing material 2 and the outer material 2 exceeds 0.050% by mass. [Effects of the Invention]

[0034] According to the present invention, it is possible to provide an aluminum alloy brazing sheet with excellent brazing properties in brazing in an inert gas atmosphere without the use of flux. [Brief explanation of the drawing]

[0035] [Figure 1] This is a diagram showing the test specimens used in the jaw opening overlap test. [Figure 2] This is a schematic diagram of an X-ray CT image obtained by fillet-shaped X-ray CT. [Modes for carrying out the invention]

[0036] The first embodiment of the present invention is an aluminum alloy brazing sheet having a core made of pure aluminum or an aluminum alloy, and an internal brazing material 1 and a cladding material 1 clad on at least one side of the core in the order of cladding material 1 / internal brazing material 1 / core, and is an aluminum alloy brazing sheet used for brazing in an inert gas atmosphere without using flux. The internal brazing material 1 is made of an aluminum alloy containing 6.00 to 13.00 mass% Si, more than 0.50 mass% and 4.50 mass% or less Mg, and 0.010 to 0.50 mass% Bi, with the remainder being aluminum and unavoidable impurities. The aforementioned coating material 1 is an aluminum alloy containing 6.00 to 13.00 mass% of Si and more than 0.050 mass% and 0.50 mass% or less of Mg, with a Bi content of 1.00 mass% or less, and the remainder being aluminum and unavoidable impurities. This is an aluminum alloy brazing sheet characterized by the following features.

[0037] Furthermore, the second embodiment of the present invention is an aluminum alloy brazing sheet having a core made of pure aluminum or an aluminum alloy, and a sacrificial anode material B1, internal brazing material 1, and core material 1 clad on at least one side of the core in the order of skin material 1 / internal brazing material 1 / sacrificial anode material B1 / core material, and is an aluminum alloy brazing sheet used for brazing in an inert gas atmosphere without using flux. The internal brazing material 1 is made of an aluminum alloy containing 6.00 to 13.00 mass% Si, more than 0.50 mass% and 4.50 mass% or less Mg, and 0.010 to 0.50 mass% Bi, with the remainder being aluminum and unavoidable impurities. The aforementioned outer material 1 contains 6.00 to 13.00 mass% of Si and Mg in amounts exceeding 0.050 mass% and 0.50 mass% or less, with a Bi content of 1.00 mass% or less, and is made of an aluminum alloy consisting of the remainder being aluminum and unavoidable impurities. The sacrificial anode material B1 contains one or more of the following: 5.00 mass% or less of Si, 1.50 mass% or less of Fe, 2.00 mass% or less of Cu, 2.00 mass% or less of Mn, 3.00 mass% or less of Mg, 6.00 mass% or less of Zn, 0.30 mass% or less of Cr, 0.30 mass% or less of Ti, and 0.30 mass% or less of Zr, with the remainder being aluminum and unavoidable impurities. This is an aluminum alloy brazing sheet characterized by the following features.

[0038] The first embodiment of the present invention and the second embodiment of the present invention are aluminum alloy brazing sheets that are formed in the shape of the components of an aluminum alloy heat exchanger and brazed by brazing heating in an inert gas atmosphere without the use of flux, in other words, aluminum alloy brazing sheets for the manufacture of an aluminum alloy heat exchanger, and are aluminum alloy brazing sheets used in the manufacture of an aluminum alloy heat exchanger by brazing in an inert gas atmosphere without the use of flux.

[0039] The first embodiment of the present invention provides an aluminum alloy brazing sheet having an internal brazing material 1 and a skin material 1 clad on at least one side of the core material in the order of skin material 1 / internal brazing material 1 / core material. In other words, the first embodiment of the present invention provides at least one side of the core material with an outermost skin material 1 and an internal brazing material 1 one layer inside the skin material 1. Furthermore, the other side of the core material of the first embodiment of the present invention, i.e., the side opposite to the side clad with the internal brazing material 1 and skin material 1, may be left unclad or may be clad with one or more clading materials. Examples of the form of the aluminum alloy brazing sheet according to the first embodiment of the present invention include a 3-layer material clad in the order of skin material 1 / internal brazing material 1 / core material, a 4-layer material clad in the order of skin material 1 / internal brazing material 1 / core material / sacrificial anode material A, a 4-layer material clad in the order of skin material 1 / internal brazing material 1 / core material / outer brazing material, a 5-layer material clad in the order of skin material 1 / internal brazing material 1 / core material / sacrificial anode material A / outer brazing material, a 5-layer material clad in the order of skin material 1 / internal brazing material 1 / core material / internal brazing material 2 / skin material 2, and a 6-layer material clad in the order of skin material 1 / internal brazing material 1 / core material / sacrificial anode material A / internal brazing material 2 / skin material 2. Furthermore, if the aluminum alloy brazing sheet of the first embodiment of the present invention has internal brazing material 2 and internal brazing material 2 in addition to internal brazing material 1 and internal brazing material 1, internal brazing material 1 and internal brazing material 2 may have the same chemical composition or different chemical compositions, and internal brazing material 1 and internal brazing material 2 may have the same chemical composition or different chemical compositions.

[0040] The second embodiment of the aluminum alloy brazing sheet of the present invention has a sacrificial anode material B1, internal brazing material 1, and skin material 1 clad on at least one side of the core material in the order of skin material 1 / internal brazing material 1 / sacrificial anode material B1 / core material. In other words, the second embodiment of the aluminum alloy brazing sheet of the present invention has at least a skin material 1 as the outermost layer, an internal brazing material 1 one layer inside the skin material 1, and a sacrificial anode material B1 one layer inside the internal brazing material 1 on one side of the core material. Furthermore, the other side of the aluminum alloy brazing sheet of the second embodiment of the present invention, i.e., the side opposite to the side clad with sacrificial anode material B1, internal brazing material 1, and skin material 1, may be unclad or may be clad with one or more clading materials. Examples of the form of the aluminum alloy brazing sheet in the second embodiment of the present invention include a 4-layer material clad in the order of skin material 1 / internal brazing material 1 / sacrificial anode material B1 / core material, a 5-layer material clad in the order of skin material 1 / internal brazing material 1 / sacrificial anode material B1 / core material / sacrificial anode material B2, a 5-layer material clad in the order of skin material 1 / internal brazing material 1 / sacrificial anode material B1 / core material / outer brazing material, a 6-layer material clad in the order of skin material 1 / internal brazing material 1 / sacrificial anode material B1 / core material / sacrificial anode material B2 / outer brazing material, a 6-layer material clad in the order of skin material 1 / internal brazing material 1 / sacrificial anode material B1 / core material / internal brazing material 2 / skin material 2, and a 7-layer material clad in the order of skin material 1 / internal brazing material 1 / sacrificial anode material B1 / core material / sacrificial anode material B2 / internal brazing material 2. Furthermore, if the aluminum alloy brazing sheet of the second embodiment of the present invention has sacrificial anode material B2 in addition to sacrificial anode material B1, sacrificial anode material B1 and sacrificial anode material B2 may have the same chemical composition or different chemical compositions. Also, if the aluminum alloy brazing sheet of the second embodiment of the present invention has internal brazing material 2 and internal brazing material 2 in addition to internal brazing material 1 and outer material 1, internal brazing material 1 and internal brazing material 2 may have the same chemical composition or different chemical compositions, and outer material 1 and outer material 2 may have the same chemical composition or different chemical compositions.

[0041] The core material of the aluminum alloy brazing sheet in the first embodiment of the present invention and the core material of the aluminum alloy brazing sheet in the second embodiment of the present invention are the same. Also, the skin material 1 and skin material 2 of the aluminum alloy brazing sheet in the first embodiment of the present invention and the skin material 1 and skin material 2 of the aluminum alloy brazing sheet in the second embodiment of the present invention are the same. The internal brazing material 1 of the aluminum alloy brazing sheet in the first embodiment of the present invention and the internal brazing material 1 of the aluminum alloy brazing sheet in the second embodiment of the present invention are the same. The sacrificial anode material A of the aluminum alloy brazing sheet in the first embodiment of the present invention and the sacrificial anode material B1 and sacrificial anode material B2 of the aluminum alloy brazing sheet in the second embodiment of the present invention are the same. The external brazing material of the aluminum alloy brazing sheet in the first embodiment of the present invention and the external brazing material of the aluminum alloy brazing sheet in the second embodiment of the present invention are the same. The internal brazing material 2 of the aluminum alloy brazing sheet in the first embodiment of the present invention and the internal brazing material 2 of the aluminum alloy brazing sheet in the second embodiment of the present invention are the same.

[0042] The core material of the aluminum alloy brazing sheet according to the first embodiment of the present invention and the aluminum alloy brazing sheet according to the second embodiment of the present invention is made of pure aluminum or an aluminum alloy.

[0043] When the core material is made of pure aluminum, the Al purity of the pure aluminum is not particularly limited, but 99.0% by mass or higher is preferred, and 99.5% by mass or higher is particularly preferred. Examples of pure aluminum materials include A1100, A1050, A1080, etc.

[0044] When the core material is made of an aluminum alloy, the composition of the aluminum alloy forming the core material is not particularly limited, as long as it can be used as the core material for an aluminum alloy brazing sheet for the manufacture of an aluminum alloy heat exchanger. Preferably, the core material is made of an aluminum alloy containing one or more of the following: 1.50% by mass or less of Si, 1.50% by mass or less of Fe, 2.00% by mass or less of Cu, 2.00% by mass or less of Mn, 3.00% by mass or less of Zn, 0.30% by mass or less of Cr, 0.30% by mass or less of Ti, and 0.30% by mass or less of Zr, with the remainder being aluminum and unavoidable impurities.

[0045] In the core material of an aluminum alloy, silicon (Si) contributes to improved strength. When the core material contains Si, the Si content in the core material is 1.50% by mass or less, preferably 0.10 to 1.00% by mass. Having a Si content within this range increases the strength of the core material. On the other hand, if the Si content in the core material exceeds this range, the melting point becomes too low, causing localized melting during brazing, leading to deformation of the core material and reduced corrosion resistance.

[0046] Fe contributes to improved strength. When the core material contains Fe, the Fe content in the core material is 1.50% by mass or less, preferably 0.10 to 0.70% by mass. When the Fe content in the core material is within the above range, the strength of the core material is increased. On the other hand, if the Fe content in the core material exceeds the above range, corrosion resistance decreases and large precipitates are more likely to occur.

[0047] Cu contributes to strength improvement and potential adjustment. When the core material contains Cu, the Cu content in the core material is 2.00% by mass or less, preferably 0.10 to 1.00% by mass. Having the Cu content in the core material within this range increases the strength of the core material. On the other hand, if the Cu content in the core material exceeds this range, intergranular corrosion becomes more likely, and the melting point becomes too low.

[0048] Mn contributes to strength improvement and potential adjustment. When the core material contains Mn, the Mn content in the core material is 2.00% by mass or less, preferably 0.30 to 1.80% by mass. When the Mn content in the core material is within the above range, the strength of the core material is increased and the potential adjustment effect is obtained. If the Mn content in the core material exceeds the above range, cracking is more likely to occur during material rolling.

[0049] Zn contributes to potential adjustment. When the core material contains Zn, the Zn content in the core material is 3.00% by mass or less, preferably 0.50 to 3.00% by mass. The potential adjustment effect is obtained when the Zn content in the core material is within the above range. On the other hand, if the Zn content in the core material exceeds the above range, the natural electrode potential becomes too low, and corrosion resistance decreases.

[0050] Cr improves strength through solid solution strengthening and also precipitates Al-Cr-based fine compounds, which contribute to grain coarsening after brazing. The Cr content in the core material is 0.30% by mass or less, preferably 0.10 to 0.20% by mass. When the Cr content in the core material is within this range, the strength of the core material is increased. On the other hand, if the Cr content in the core material exceeds this range, large intermetallic compounds are more likely to form during casting, resulting in reduced plastic workability.

[0051] Ti improves strength through solid solution strengthening, and its layered distribution creates layers of high and low potential within the core material, resulting in a layered corrosion mode instead of pitting corrosion, thus improving corrosion resistance. The Ti content in the core material is 0.30% by mass or less, preferably 0.10 to 0.20% by mass. When the Ti content in the core material is within this range, the strength of the core material increases, and its corrosion resistance improves. On the other hand, if the Ti content in the core material exceeds this range, large intermetallic compounds are more likely to form during casting, resulting in reduced plastic workability.

[0052] Zr improves strength through solid solution strengthening and also precipitates Al-Zr-based fine compounds, which contribute to grain coarsening after brazing. The Zr content in the core material is 0.30% by mass or less, preferably 0.10 to 0.20% by mass. When the Zr content in the core material is within this range, the strength of the core material is increased and the effect of grain coarsening after brazing is obtained. On the other hand, if the Zr content in the core material exceeds this range, large intermetallic compounds are more likely to form during casting, resulting in poor plastic workability.

[0053] The core material may contain Mg. In the core material of an aluminum alloy, Mg diffuses into the internal brazing material 1 or outer layer 1 during brazing heating, promoting the destruction of the oxide film on the material surface and contributing to improved brazing properties. When the core material contains Mg, the Mg content in the core material is 3.00% by mass or less, preferably 0.30 to 1.80% by mass. When the Mg content in the core material is within the above range, the effect of improving brazing properties is easily obtained. On the other hand, if the Mg content in the core material exceeds the above range, cracking is more likely to occur during material rolling.

[0054] The core material may contain Bi. In the aluminum alloy forming the core material, when the internal brazing material 1 or the outer layer 1 melts during brazing heating and melts a portion of the core material, Bi acts to suppress the decrease in the Bi concentration of the internal brazing material 1 or the outer layer 1, and promotes the destruction of the oxide film by Mg. When the core material contains Bi, the Bi content in the core material is 0.50% by mass or less, preferably 0.10 to 0.40% by mass. By having a Bi content in the core material within the above range, the effect of promoting the destruction of the oxide film by Mg is obtained. On the other hand, if it exceeds the above range, cracks are more likely to occur during material manufacturing, making it difficult to manufacture brazing sheets.

[0055] The core material may contain 0.050% by mass or less of Ag, B, Be, Ca, Cd, Co, Ga, Ge, Hg, In, Li, Mo, Na, Ni, P, Pb, Sb, Sn, Sr, V, and Y as unavoidable impurities.

[0056] The internal brazing material 1 and internal brazing material 2 relating to the first embodiment of the aluminum alloy brazing sheet and the second embodiment of the aluminum alloy brazing sheet of the present invention are made of an aluminum alloy containing 6.00 to 13.00 mass% of Si, more than 0.50 mass% and 4.50 mass% or less of Mg, and 0.010 to 0.50 mass% of Bi, with the remainder being aluminum and unavoidable impurities.

[0057] Internal brazing material 1 and internal brazing material 2 contain Si. In aluminum alloy brazing materials, Si contributes to brazing properties. The Si content in internal brazing material 1 and internal brazing material 2 is 6.00 to 13.00 mass%. Sufficient brazing properties can be obtained when the Si content in internal brazing material 1 and internal brazing material 2 is within the above range. If the Si content in internal brazing material 1 and internal brazing material 2 is below the above range, the bonding properties will be poor, and if it exceeds the above range, cracking will easily occur during material manufacturing, making it difficult to manufacture brazing sheets.

[0058] Internal brazing material 1 and internal brazing material 2 contain Mg. The Mg content in internal brazing material 1 and internal brazing material 2 is greater than 0.50% by mass and 4.50% by mass or less, preferably 0.60 to 4.00% by mass. By having the Mg content in internal brazing material 1 and internal brazing material 2 within the above range, sufficient brazing joint properties can be obtained. If the Mg content in internal brazing material 1 and internal brazing material 2 is below the above range, the effect of breaking down the oxide film will be poor, and if it exceeds the above range, cracks will easily occur during material manufacturing, making it difficult to manufacture brazing sheets.

[0059] Internal brazing material 1 and internal brazing material 2 contain Bi. The Bi content in internal brazing material 1 and internal brazing material 2 is 0.010 to 0.50 mass%, preferably 0.020 to 0.45 mass%. By having the Bi content in internal brazing material 1 and internal brazing material 2 within the above range, sufficient brazing joint properties can be obtained. If the Bi content in internal brazing material 1 and internal brazing material 2 is below the above range, the effect of promoting the destruction of the oxide film by Mg will be reduced, and if it exceeds the above range, cracks will easily occur during material manufacturing, making it difficult to manufacture brazing sheets.

[0060] Internal brazing materials 1 and 2 may contain one or more of Na, Sr, and Sb. In the aluminum alloy forming the brazing material, Na, Sr, and Sb have the effect of refining the Si particles in the brazing material and improving the fluidity of the brazing material. When internal brazing materials 1 and 2 contain Na, the Na content is 0.050% by mass or less, preferably 0.005 to 0.040% by mass. When internal brazing materials 1 and 2 contain Sr, the Sr content is 0.050% by mass or less, preferably 0.005 to 0.040% by mass. When internal brazing materials 1 and 2 contain Sb, the Sb content is 0.050% by mass or less, preferably 0.005 to 0.040% by mass. By having the Na, Sr, and Sb content in internal brazing materials 1 and 2 within the above ranges, the Si particle refinement effect can be obtained. On the other hand, if the Na, Sr, and Sb content in internal brazing material 1 and internal brazing material 2 exceeds the above range, the effect becomes saturated and it is not economical.

[0061] Internal brazing material 1 and internal brazing material 2 may contain one or two of Zn and Cu. In the aluminum alloy forming internal brazing material 1 and internal brazing material 2, Zn and Cu lower the melting point of the brazing material, enabling brazing at a temperature lower than the typical brazing temperature of 600°C.

[0062] When internal brazing material 1 and internal brazing material 2 contain Zn, the Zn content is preferably 6.00% by mass or less, particularly preferably 1.00 to 5.50% by mass, and even more preferably 3.00 to 5.00% by mass, in that it is easier to obtain the effect of lowering the melting point of the brazing material. On the other hand, if the Zn content in internal brazing material 1 and internal brazing material 2 exceeds the above range, cracking will occur during material manufacturing, making it difficult to manufacture the brazing sheet. Furthermore, when internal brazing material 1 and internal brazing material 2 contain Zn, it is preferable that the Zn content in internal brazing material 1 and internal brazing material 2 be 3.00% by mass or less, in that it is easier to obtain the effect of preventing corrosion of the core material by making the potential of the brazing material negative and preferentially corroding the core material.

[0063] When internal brazing material 1 and internal brazing material 2 contain Cu, the Cu content is 2.00% by mass or less, preferably 0.50 to 2.00% by mass, and particularly preferably 1.00 to 2.00% by mass. Having the Cu content in internal brazing material 1 and internal brazing material 2 within the above range enhances the effect of lowering the melting point of the brazing material. On the other hand, if the Cu content in internal brazing material 1 and internal brazing material 2 exceeds the above range, cracks will occur during material manufacturing, making it difficult to manufacture the brazing sheet.

[0064] Internal brazing material 1 and internal brazing material 2 may contain Fe. In the aluminum alloy forming the brazing material, Fe precipitates relatively coarse Al-Fe compounds, which contribute to grain refinement of the remaining brazing material after brazing. When internal brazing material 1 and internal brazing material 2 contain Fe, the Fe content in internal brazing material 1 and internal brazing material 2 is 1.00% by mass or less, preferably 0.10 to 0.50% by mass. When the Fe content in internal brazing material 1 and internal brazing material 2 is within the above range, the grain refinement effect is more easily obtained. On the other hand, if the Fe content of internal brazing material 1 and internal brazing material 2 exceeds the above range, large intermetallic compounds are more likely to form during casting, resulting in lower plastic workability.

[0065] Internal brazing material 1 and internal brazing material 2 may contain one or more of Mn, Cr, Ti, and Zr. In the aluminum alloy forming the brazing material, Mn, Cr, Ti, and Zr precipitate Al-Mn, Al-Cr, Al-Ti, and Al-Zr fine compounds, respectively, and act to coarse the crystal grains of the remaining brazing material after brazing.

[0066] When internal brazing material 1 and internal brazing material 2 contain Mn, the Mn content is 2.00% by mass or less, preferably 0.10 to 0.60% by mass. Having the Mn content in internal brazing material 1 and internal brazing material 2 within this range makes it easier to achieve the grain coarsening effect. On the other hand, if the Mn content in internal brazing material 1 and internal brazing material 2 exceeds this range, large intermetallic compounds are more likely to form during casting, resulting in reduced plasticity.

[0067] When internal brazing material 1 and internal brazing material 2 contain Cr, the Cr content is 0.30% by mass or less, preferably 0.10 to 0.20% by mass. Having the Cr content in internal brazing material 1 and internal brazing material 2 within this range makes it easier to achieve the grain coarsening effect. On the other hand, if the Cr content in internal brazing material 1 and internal brazing material 2 exceeds this range, large intermetallic compounds are more likely to form during casting, resulting in reduced plasticity.

[0068] When internal brazing material 1 and internal brazing material 2 contain Ti, the Ti content is 0.30% by mass or less, preferably 0.10 to 0.20% by mass. Having the Ti content in internal brazing material 1 and internal brazing material 2 within this range makes it easier to achieve the effect of grain coarsening. On the other hand, if the Ti content in internal brazing material 1 and internal brazing material 2 exceeds this range, large intermetallic compounds are more likely to form during casting, resulting in reduced plasticity.

[0069] When internal brazing material 1 and internal brazing material 2 contain Zr, the Zr content is 0.30% by mass or less, preferably 0.10 to 0.20% by mass. Having the Zr content in internal brazing material 1 and internal brazing material 2 within this range makes it easier to achieve the grain coarsening effect. On the other hand, if the Zr content in internal brazing material 1 and internal brazing material 2 exceeds this range, large intermetallic compounds are more likely to form during casting, resulting in reduced plasticity.

[0070] The crystal grain size after brazing is adjusted by utilizing the above-mentioned action, and the effects of the present invention can be fully obtained within the above range.

[0071] Internal brazing material 1 and internal brazing material 2 may contain Ag, B, Be, Ca, Cd, Co, Ga, Ge, Hg, In, Li, Mo, Ni, P, Pb, Sn, V, and Y as unavoidable impurities in amounts of 0.050 mass or less.

[0072] The aluminum alloy brazing sheet according to the first embodiment of the present invention and the aluminum alloy brazing sheet according to the second embodiment of the present invention, respectively, are made of an aluminum alloy containing 6.00 to 13.00 mass% of Si and Mg exceeding 0.050 mass% and 0.50 mass% or less, with a Bi content of 1.00 mass% or less, and the remainder being aluminum and unavoidable impurities.

[0073] Both the outer layer 1 and outer layer 2 contain Si. The Si in outer layer 1 and outer layer 2 contributes to brazing performance by reducing the decrease in Si content of inner brazing material 1 and inner brazing material 2 when outer layer 1 and outer layer 2 melt together with inner brazing material 1 and inner brazing material 2, respectively, at the brazing temperature. The Si content in outer layer 1 and outer layer 2 is 6.00 to 13.00 mass%. Sufficient brazing performance can be obtained when the Si content in outer layer 1 and outer layer 2 is within the above range. On the other hand, if the Si content in outer layer 1 and outer layer 2 is below the above range, it will decrease the Si content of inner brazing material 1 and inner brazing material 2, reducing brazing performance. Furthermore, if it exceeds the above range, cracking is more likely to occur during material manufacturing, making it difficult to manufacture brazing sheets.

[0074] The outermost layers, layers 1 and 2, contain Mg. Because layers 1 and 2, which are the outermost layers, contain Mg, a small amount of Mg on the outermost surface of layers 1 and 2 evaporates during brazing, reducing the oxidizing components in the atmosphere surrounding the material surface and creating an atmosphere with extremely low levels of oxidizing components. This prevents re-oxidation of the material surface and improves brazing performance. The Mg content in layers 1 and 2 is greater than 0.050% by mass and less than or equal to 0.50% by mass. When the Mg content in the layers is within this range, the Mg on the outermost surface of layers 1 and 2 evaporates during brazing, trapping the oxidizing components in the atmosphere, preventing re-oxidation and improving brazing performance. On the other hand, if the Mg content in layers 1 and 2 is below this range, the trapping effect of the oxidizing components in the atmosphere becomes poor, and if it exceeds this range, Mg oxidizes during brazing, forming MgO, resulting in lower brazing performance.

[0075] The coating material 1 and coating material 2 may contain 1.00% by mass or less of Bi. The Bi content in the coating material is preferably 0.050% by mass or less.

[0076] Coating material 1 and coating material 2 may contain one or more of Na, Sr, and Sb. In the aluminum alloy forming coating material 1 and coating material 2, Na, Sr, and Sb have the effect of refining the Si particles in coating material 1 and coating material 2 and improving the fluidity of the wax. When coating material 1 and coating material 2 contain Na, the Na content is 0.050% by mass or less, preferably 0.005 to 0.040% by mass. When coating material 1 and coating material 2 contain Sr, the Sr content is 0.050% by mass or less, preferably 0.005 to 0.040% by mass. When coating material 1 and coating material 2 contain Sb, the Sb content is 0.050% by mass or less, preferably 0.005 to 0.040% by mass. The Si particle refinement effect is obtained by having the Na, Sr, and Sb content in coating material 1 and coating material 2 within the above ranges. On the other hand, if the Na, Sr, and Sb content in material 1 and material 2 exceeds the above range, the effect becomes saturated and it is not economical.

[0077] The outer layer 1 and outer layer 2 may contain one or two of Zn and Cu. In the aluminum alloy forming outer layer 1 and outer layer 2, Zn and Cu lower the melting points of outer layer 1 and outer layer 2, enabling them to melt with the inner brazing material 1 and inner brazing material 2, respectively, at a temperature lower than the typical brazing temperature of 600°C.

[0078] When the outer layer 1 and outer layer 2 contain Zn, the Zn content is preferably 6.00% by mass or less, particularly preferably 1.00 to 5.50% by mass, and even more preferably 3.00 to 5.00% by mass, in that it is easier to obtain the effect of lowering the melting point of the outer layer 1 and outer layer 2. On the other hand, if the Zn content in the outer layer 1 and outer layer 2 exceeds the above range, cracking will occur during material manufacturing, making it difficult to manufacture the brazing sheet. Furthermore, when the outer layer 1 and outer layer 2 contain Zn, it is preferable that the Zn content in the outer layer 1 and outer layer 2 is 3.00% by mass or less, in that it is easier to obtain the effect of preventing corrosion of the core material by making the potential of the outer layer 1 and outer layer 2 negative and preferentially corroding the core material.

[0079] When material 1 and material 2 contain Cu, the Cu content is 2.00% by mass or less, preferably 0.50 to 2.00% by mass, and particularly preferably 1.00 to 2.00% by mass. Having the Cu content in material 1 and material 2 within the above range enhances the effect of lowering the melting point of material 1 and material 2. On the other hand, if the Cu content in material 1 and material 2 exceeds the above range, cracking occurs during material manufacturing, making it difficult to manufacture the brazing sheet.

[0080] Coating material 1 and coating material 2 may contain Fe. In the aluminum alloy forming coating material 1 and coating material 2, Fe precipitates relatively coarse Al-Fe compounds, which dissolve with the brazing material during brazing and contribute to grain refinement of the remaining brazing material after brazing. When coating material 1 and coating material 2 contain Fe, the Fe content in coating material 1 and coating material 2 is 1.00% by mass or less, preferably 0.10 to 0.50% by mass. When the Fe content in coating material 1 and coating material 2 is within the above range, the grain refinement effect is more easily obtained. On the other hand, if the Fe content of coating material 1 and coating material 2 exceeds the above range, large intermetallic compounds are more likely to form during casting, resulting in lower plasticity.

[0081] The outer layer 1 and outer layer 2 may contain one or more of Mn, Cr, Ti, and Zr. In the aluminum alloy forming outer layer 1 and outer layer 2, Mn, Cr, Ti, and Zr precipitate Al-Mn, Al-Cr, Al-Ti, and Al-Zr fine compounds, respectively, and act to coarse the crystal grains of the remaining brazing material after brazing.

[0082] When both the outer layer 1 and outer layer 2 contain Mn, the Mn content is 2.00% by mass or less, preferably 0.10 to 0.60% by mass. Having the Mn content in outer layer 1 and outer layer 2 within this range makes it easier to achieve the grain coarsening effect. On the other hand, if the Mn content in outer layer 1 and outer layer 2 exceeds this range, large intermetallic compounds are more likely to form during casting, resulting in reduced plasticity.

[0083] When both the outer layer 1 and outer layer 2 contain Cr, the Cr content in both layers 1 and 2 is 0.30% by mass or less, preferably 0.10 to 0.20% by mass. Having the Cr content in layers 1 and 2 within this range makes it easier to achieve the grain coarsening effect. On the other hand, if the Cr content in layers 1 and 2 exceeds this range, large intermetallic compounds are more likely to form during casting, resulting in reduced plasticity.

[0084] When both the outer layer 1 and outer layer 2 contain Ti, the Ti content is 0.30% by mass or less, preferably 0.10 to 0.20% by mass. Having the Ti content in outer layer 1 and outer layer 2 within this range makes it easier to achieve the grain coarsening effect. On the other hand, if the Ti content in outer layer 1 and outer layer 2 exceeds this range, large intermetallic compounds are more likely to form during casting, resulting in reduced plasticity.

[0085] When both the outer layer 1 and outer layer 2 contain Zr, the Zr content is 0.30% by mass or less, preferably 0.10 to 0.20% by mass. Having the Zr content in outer layer 1 and outer layer 2 within this range makes it easier to achieve the grain coarsening effect. On the other hand, if the Zr content in outer layer 1 and outer layer 2 exceeds this range, large intermetallic compounds are more likely to form during casting, resulting in reduced plasticity.

[0086] The crystal grain size after brazing is adjusted by utilizing the above-mentioned action, and the effects of the present invention can be fully obtained within the above range.

[0087] The coating material 1 and coating material 2 may contain Ag, B, Be, Ca, Cd, Co, Ga, Ge, Hg, In, Li, Mo, Ni, P, Pb, Sn, V, and Y as unavoidable impurities in amounts of 0.050% by mass or less.

[0088] Furthermore, in the first embodiment of the aluminum alloy brazing sheet and the second embodiment of the aluminum alloy brazing sheet of the present invention, the internal brazing material 1 contains Mg in an amount greater than 0.50% by mass and less than or equal to 4.50% by mass, and Bi in an amount of 0.010 to 0.50% by mass, and the outer material 1 contains Mg in an amount greater than 0.050% by mass and less than or equal to 0.50% by mass.

[0089] Because the free energy for oxide formation of magnesium (Mg) added to the brazing material layer is lower than that of aluminum, it can reduce and destroy the aluminum-based surface oxide film during brazing heating. However, in a two-layer aluminum alloy brazing sheet composed of brazing material and core material, materials with Mg added to the brazing material cannot be brazed because MgO is formed during the heat treatment process in material manufacturing. Therefore, it is necessary to remove this MgO through pretreatment. In addition, even before the brazing material melts during brazing heating, the Mg in the brazing material destroys the oxide film on the material surface that does not yet need to be destroyed, causing a thick and strong oxide film to grow before the brazing material melts. Furthermore, because this oxide film contains Mg, reduction and destruction of the oxide film by the same Mg is unlikely to occur, and sufficient brazing properties cannot be obtained.

[0090] Furthermore, in a two-layer aluminum alloy brazing sheet composed of a brazing material and a core material, a material in which Mg is added to the core material has the advantage of preventing the formation of MgO during material manufacturing and brazing heating because Mg is not present in the brazing material. However, due to constraints such as formability, there is a limit to the amount of Mg that can be added to the core material, so high-temperature, long-duration brazing heating is required to diffuse the Mg in the core material into the oxide film. In a practical brazing atmosphere, high-temperature, long-duration brazing promotes the oxidation of the aluminum itself, causing the oxide film to grow thicker, which significantly reduces brazing performance.

[0091] Furthermore, by cladding a high-Mg concentration intermediate layer between the brazing material and the core material, Mg can be supplied from the intermediate layer without adding Mg to the brazing material, making it possible to break down the oxide film to a certain extent efficiently. This material exhibits high brazing properties even with relatively short brazing heating times. However, in practical brazing atmospheres, the aluminum itself oxidizes and a thick, strong oxide film grows, so practical brazing properties cannot be obtained unless the brazing conditions are suitable for the material.

[0092] In addition, the breakdown of the oxide film by Mg proceeds relatively slowly, influenced by temperature and time. Therefore, in practical products containing Mg, if a temperature difference occurs within the product during brazing, the breakdown of the oxide film by Mg will proceed faster in some areas and slower in others, resulting in uneven fillet formation. Consequently, molten solder flows into joints where fillets have already formed due to capillary force, while molten solder flows out of joints where fillets have not yet formed, preventing fillet formation even if the oxide film is subsequently broken. Therefore, in practical products with numerous joints, critical non-joints occur. Thus, to obtain sufficient brazing performance in practical products containing Mg, it is important to cause uniform and instantaneous breakdown of the oxide film by Mg to enable brazing.

[0093] To uniformly and instantaneously destroy the oxide film, one method is to add Mg to the brazing material layer and then clad a Mg-free cladding layer on the side of the brazing material layer opposite the core. That is, before the brazing heat melts, the cladding layer on the outermost surface does not contain Mg, so the oxide film on the material surface remains thin. However, once the brazing material layer melts, the Mg contained in the brazing material layer can quickly reach the surface of the cladding layer and destroy the oxide film. However, even in materials with a cladding layer as described above, the Mg concentration in the brazing material layer is low, on the order of a few percent, so the effect of reducing and destroying the oxide film is slow, and sufficient brazing properties cannot be obtained in practical products. On the other hand, if a large amount of Mg is added to the brazing material, cracking is likely to occur during material manufacturing, making it difficult to manufacture brazing sheets.

[0094] Therefore, after diligent research by the present inventors, we discovered that using Bi is an effective method for increasing the concentration of Mg that acts on the material surface during melting of the wax, without increasing the Mg content added to the wax layer.

[0095] Bi combines with Mg to form an intermetallic compound consisting of Mg3Bi2, but the Mg concentration in the Mg3Bi2 compound is extremely high at 85% by mass. Therefore, by applying Mg3Bi2 to an oxide film, it is possible to rapidly accelerate the breakdown of the oxide film, bringing the brazing properties to a practical level.

[0096] Furthermore, practical products include joints that are not easily exposed to the brazing atmosphere, such as large-area joints with clearances of 1 mm or less. The inventors have found that if the material of this joint contains Mg on its outermost surface, the Mg evaporates slightly during brazing heating, reducing the oxidizing components in the atmosphere on the material surface and forming an atmosphere with extremely low levels of oxidizing components, thereby preventing re-oxidation of the material surface and improving brazing properties.

[0097] In other words, in the first embodiment of the aluminum alloy brazing sheet of the present invention and the second embodiment of the aluminum alloy brazing sheet of the present invention, the desired brazing properties are obtained by including in the internal brazing material 1 more than 0.50% by mass and 4.50% by mass or less Mg and 0.010 to 0.50% by mass Bi, and in the outer material 1 more than 0.050% by mass and 0.50% by mass or less Mg.

[0098] Furthermore, when brazing is performed, the internal brazing material layer and the outer layer melt and mix together, causing the Mg and Bi concentrations to decrease. As a result, Mg3Bi2 decomposes in the molten brazing material before it can act on the oxide film. Therefore, the inventors have found that brazing performance can be further improved by controlling not only the Mg concentration in the internal brazing material layer, but also the average value of the Mg and Bi concentrations added to the internal brazing material layer and the outer layer in the thickness direction.

[0099] In other words, in the first embodiment of the aluminum alloy brazing sheet of the present invention and the second embodiment of the aluminum alloy brazing sheet of the present invention, the brazing properties are further improved by setting the average Mg concentration in the thickness direction of the internal brazing material 1 and the outer layer 1 to a concentration of more than 0.50 mass%, and the average Bi concentration in the thickness direction of the internal brazing material 1 and the outer layer 1 to a concentration of more than 0.050 mass%.

[0100] The average Mg concentration in the thickness direction of the internal brazing material 1 and the outer layer 1 is preferably greater than 0.50% by mass, more preferably 0.65% by mass or more, and even more preferably 0.80% by mass or more. Having the average Mg concentration in the thickness direction of the internal brazing material 1 and the outer layer 1 within the above range increases the stability of Mg3Bi2 and sufficiently delays its decomposition in the molten brazing material. From the viewpoint of brazing properties, a higher average Mg concentration in the thickness direction of the internal brazing material 1 and the outer layer 1 is preferable, and there is no upper limit; rather, it is determined by the upper limit of the Mg content of the internal brazing material 1, which will be described separately.

[0101] The average Bi concentration in the thickness direction of the internal brazing material 1 and the outer layer 1 is preferably greater than 0.050% by mass, more preferably 0.065% by mass or more, and even more preferably 0.080% by mass or more. Having the average Bi concentration in the thickness direction of the internal brazing material 1 and the outer layer 1 within the above range increases the stability of Mg3Bi2 and sufficiently delays its decomposition in the molten brazing material. From the viewpoint of brazing properties, a higher average Bi concentration in the thickness direction of the internal brazing material 1 and the outer layer 1 is preferable, and there is no upper limit to the concentration; rather, it is determined by the upper limit of the Bi content of the internal brazing material 1, which will be described separately.

[0102] If the Mg and Bi concentrations are low, Mg3Bi2 decomposes during brazing heating, so the brazing improvement effect cannot be fully obtained. Furthermore, not only does the Mg concentration in the internal brazing layer decrease, but the Mg and Bi concentrations also decrease as the internal brazing layer and the outer layer melt and mix, causing Mg3Bi2 to decompose in the molten brazing solution before it can act on the oxide film. Therefore, the inventors diligently investigated the Mg and Bi concentrations that yield good brazing performance and found that brazing performance can be improved by setting the Mg content added to the internal brazing layer and the outer layer, and the Bi content added to the internal brazing layer, within a predetermined range. In this invention, the average Mg concentration in the thickness direction of the internal brazing material 1 and the outer layer 1, and the average Bi concentration in the thickness direction of the internal brazing material 1 and the outer layer 1 are determined as follows, where A is 1% by mass of the Mg content of the internal brazing material 1, B is 1% by mass of the Bi content of the internal brazing material 1, C is 1% by mass of the Mg content of the outer layer 1, D is 1% by mass of the Bi content of the outer layer 1, T is the thickness of the internal brazing material 1 (mm), and t is the thickness of the outer layer 1 (mm). Average Mg concentration (%) in the thickness direction of internal brazing material 1 and outer layer 1 = (A1 × T1 + C1 × t1) / (T1 + t1) Average Bi concentration (%) in the thickness direction of internal brazing material 1 and outer layer 1 = (B1 × T1 + D1 × t1) / (T1 + t1)

[0103] The thickness of the internal brazing material 1 is preferably 15.0 μm or more. The thicker the brazing material, the greater the absolute amount of Mg3Bi2 compound, which accelerates the breakdown of the oxide film. Furthermore, a thickness of 15.0 μm or more for the internal brazing material 1 makes it easier to adjust the average Mg concentration and average Bi concentration in the thickness direction of the internal brazing material 1 and the outer layer 1 to a predetermined concentration. Although there is no upper limit for the thickness of the internal brazing material 1, the range of thickness required for practical products is approximately 15.0 to 400 μm.

[0104] The thickness of the outer layer 1 is preferably 5.0 μm or more. The thicker the outer layer 1, the less likely the Mg in the internal brazing material 1 is to diffuse to the surface of the outer layer 1, thus improving brazing properties. By making the outer layer 1 thickness 5.0 μm or more, the high concentration of Mg in the internal brazing material 1 is less likely to diffuse to the surface of the outer layer 1, making it easier to obtain the antioxidant effect of Mg. Although there is no upper limit to the thickness of the outer layer 1, a thickness of 120 μm or less is preferable in that it is easier to adjust the average Mg concentration in the thickness direction of the internal brazing material 1 and the outer layer 1, and the average Bi concentration in the thickness direction of the internal brazing material 1 and the outer layer 1. Therefore, the practical range for the thickness of the outer layer 1 is approximately 5.0 to 120 μm.

[0105] Furthermore, in the first embodiment of the aluminum alloy brazing sheet of the present invention and the second embodiment of the aluminum alloy brazing sheet of the present invention, it is preferable that the average Mg concentration in the thickness direction of the internal brazing material 2 and the outer layer 2 is greater than 0.50% by mass, and the average Bi concentration in the thickness direction of the internal brazing material 2 and the outer layer 2 is greater than 0.050% by mass. This further improves the brazing properties.

[0106] Sacrificial anode material A for the first embodiment of the present invention, sacrificial anode material B1 for the second embodiment of the present invention, and sacrificial anode material B2 for the second embodiment of the present invention are made of an aluminum alloy containing one or more of the following: 5.00 mass% or less of Si, 1.50 mass% or less of Fe, 2.00 mass% or less of Cu, 2.00 mass% or less of Mn, 3.00 mass% or less of Mg, 6.00 mass% or less of Zn, 0.30 mass% or less of Cr, 0.30 mass% or less of Ti, and 0.30 mass% or less of Zr, with the remainder being aluminum and unavoidable impurities. Hereinafter, sacrificial anode material A, sacrificial anode material B1, and sacrificial anode material B2 will be collectively referred to simply as "sacrificial anode material".

[0107] In aluminum alloy sacrificial anode materials, Si contributes to improved strength. When the sacrificial anode material contains Si, the Si content is 5.00% by mass or less, preferably 0.10 to 1.50% by mass, and particularly preferably 0.10 to 1.00% by mass. Having a Si content within this range increases the strength of the sacrificial anode material. Alternatively, a Si content of 1.50 to 5.00% by mass, particularly preferably 2.50 to 4.50% by mass, is preferable. In the range of 1.50 to 5.00% by mass, the Si becomes semi-molten during brazing heating, supplying a small amount of liquid phase brazing material and improving brazing properties when the sacrificial anode surface becomes the brazing surface. On the other hand, if the Si content in the sacrificial anode material exceeds the above range, the melting point becomes too low, causing localized melting during brazing and deformation of the sacrificial anode material.

[0108] Fe contributes to improved strength. When the sacrificial anode material contains Fe, the Fe content in the sacrificial anode material is 1.50% by mass or less, preferably 0.10 to 0.70% by mass. When the Fe content in the sacrificial anode material is within the above range, the strength of the sacrificial anode material is increased. On the other hand, if the Fe content in the sacrificial anode material exceeds the above range, corrosion resistance decreases and large precipitates are more likely to occur.

[0109] Cu contributes to improved strength and potential adjustment. When the sacrificial anode material contains Cu, the Cu content in the sacrificial anode material is 2.00% by mass or less, preferably 0.10 to 1.00% by mass. Having a Cu content within this range in the sacrificial anode material increases its strength. On the other hand, if the Cu content in the sacrificial anode material exceeds this range, intergranular corrosion becomes more likely, and the melting point becomes too low.

[0110] Mn contributes to strength improvement and potential adjustment. When the sacrificial anode material contains Mn, the Mn content in the sacrificial anode material is 2.00% by mass or less, preferably 0.30 to 1.80% by mass. When the Mn content in the sacrificial anode material is within the above range, the strength of the sacrificial anode material is increased and a potential adjustment effect is obtained. If the Mn content in the sacrificial anode material exceeds the above range, cracking is more likely to occur during material rolling.

[0111] Mg contributes to strength improvement. When the sacrificial anode material contains Mg, the Mg content in the sacrificial anode material is 3.00% by mass or less, preferably 0.30 to 1.80% by mass. When the Mg content in the sacrificial anode material is within the above range, the effect of strength improvement is easily obtained. On the other hand, if the Mg content in the sacrificial anode material exceeds the above range, cracking is more likely to occur during material rolling.

[0112] Zn contributes to potential regulation. When the sacrificial anode material contains Zn, the Zn content in the sacrificial anode material is 6.00% by mass or less, preferably 3.00% by mass or less. Having the Zn content in the sacrificial anode material within this range enhances the sacrificial corrosion protection effect. On the other hand, if the Zn content in the sacrificial anode material exceeds this range, the potential of the sacrificial anode material may drop excessively, potentially accelerating corrosion.

[0113] Cr improves strength through solid solution strengthening and also precipitates Al-Cr-based fine compounds, which contribute to grain coarsening after brazing. The Cr content in the sacrificial anode material is 0.30% by mass or less, preferably 0.10 to 0.20% by mass. When the Cr content in the sacrificial anode material is within this range, the strength of the sacrificial anode material is increased. On the other hand, if the Cr content in the sacrificial anode material exceeds this range, large intermetallic compounds are more likely to form during casting, resulting in reduced plasticity.

[0114] Ti improves strength through solid solution strengthening, and its layered distribution creates layers of high and low potential within the sacrificial anode material, resulting in a layered corrosion mode instead of pitting corrosion, thus improving corrosion resistance. The Ti content in the sacrificial anode material is 0.30% by mass or less, preferably 0.10 to 0.20% by mass. When the Ti content in the sacrificial anode material is within this range, the strength of the sacrificial anode material increases, and its corrosion resistance improves. On the other hand, if the Ti content in the sacrificial anode material exceeds this range, large intermetallic compounds are more likely to form during casting, resulting in reduced plastic workability.

[0115] Zr improves strength through solid solution strengthening and also precipitates Al-Zr-based fine compounds, which contribute to grain coarsening after brazing. The Zr content in the sacrificial anode material is 0.30% by mass or less, preferably 0.10 to 0.20% by mass. When the Zr content in the sacrificial anode material is within the above range, the strength of the sacrificial anode material is increased, and the effect of grain coarsening after brazing is obtained. On the other hand, if the Zr content in the sacrificial anode material exceeds the above range, large intermetallic compounds are more likely to form during casting, resulting in reduced plasticity.

[0116] The sacrificial anode material may contain 0.050 mass% or less of Ag, B, Be, Bi, Ca, Cd, Co, Ga, Ge, Hg, In, Li, Mo, Na, Ni, P, Pb, Sb, Sn, Sr, V, and Y as unavoidable impurities.

[0117] The outer brazing material for the first embodiment of the aluminum alloy brazing sheet of the present invention and the outer brazing material for the second embodiment of the aluminum alloy brazing sheet of the present invention are made of an aluminum alloy containing 6.00 to 13.00 mass% of Si, and further containing one or more of the following: 1.00 mass% or less of Fe, 2.00 mass% or less of Cu, 2.00 mass% or less of Mn, 4.50 mass% or less of Mg, 6.00 mass% or less of Zn, 0.50 mass% or less of Bi, 0.30 mass% or less of Cr, 0.30 mass% or less of Ti, and 0.30 mass% or less of Zr, with the remainder being aluminum and unavoidable impurities.

[0118] The outer brazing material contains Si. In the outer brazing material of aluminum alloys, Si contributes to brazing properties. The Si content in the outer brazing material is 6.00 to 13.00 mass%. Sufficient brazing properties can be obtained when the Si content in the outer brazing material is within this range. If the Si content in the outer brazing material is below this range, the bonding properties will be poor, and if it exceeds this range, cracking will easily occur during material manufacturing, making it difficult to manufacture brazing sheets.

[0119] When the outer brazing material contains Fe, the Fe content in the outer brazing material is 1.00% by mass or less, preferably 0.10 to 0.50% by mass. When the Fe content in the outer brazing material is within this range, the effect of grain refinement is more easily obtained. On the other hand, if the Fe content of the outer brazing material exceeds this range, large intermetallic compounds are more likely to form during casting, resulting in reduced plasticity.

[0120] When the outer brazing material contains Cu, the Cu content in the outer brazing material is 2.00% by mass or less, preferably 0.50 to 2.00% by mass. Having a Cu content within this range enhances the effect of lowering the melting point of the brazing material. On the other hand, if the Cu content in the outer brazing material exceeds this range, cracking occurs during material manufacturing, making it difficult to manufacture the brazing sheet.

[0121] When the outer brazing material contains Mn, the Mn content in the outer brazing material is 2.00% by mass or less, preferably 0.10 to 0.60% by mass. Having the Mn content in the outer brazing material within this range makes it easier to achieve the grain coarsening effect. On the other hand, if the Mn content in the outer brazing material exceeds this range, large intermetallic compounds are more likely to form during casting, resulting in reduced plasticity.

[0122] When the outer brazing material contains Mg, the Mg content in the outer brazing material is 4.50% by mass or less, preferably 0.60 to 4.00% by mass. A Mg content within this range ensures sufficient brazing bonding properties. If the Mg content in the outer brazing material is below this range, the oxide film destructive effect becomes poor. If it exceeds this range, cracking becomes more likely during material manufacturing, making the production of brazing sheets difficult.

[0123] When the outer brazing material contains Zn, the Zn content in the outer brazing material is preferably 6.00% by mass or less, as this makes it easier to obtain the effect of lowering the melting point of the brazing material. On the other hand, if the Zn content in the outer brazing material exceeds 6.00% by mass, cracks will occur during material manufacturing, making it difficult to manufacture the brazing sheet. Furthermore, when the outer brazing material contains Zn, the Zn content in the outer brazing material is preferably 3.00% by mass or less, as this makes it easier to obtain the effect of preventing corrosion of the core material by making the potential of the brazing material less attractive and preferentially corroding the core material.

[0124] When the outer brazing material contains Bi, the Bi content in the outer brazing material is 0.50% by mass or less. A Bi content within this range ensures sufficient brazing properties. If the Bi content is below this range, the effect of promoting the breakdown of the oxide film by Mg is diminished. Conversely, if it exceeds this range, cracking becomes more likely during material manufacturing, making the production of brazing sheets difficult.

[0125] When the outer brazing material contains chromium (Cr), the Cr content in the outer brazing material is 0.30% by mass or less, preferably 0.10 to 0.20% by mass. Having a Cr content within this range makes it easier to achieve grain coarsening. On the other hand, if the Cr content in the outer brazing material exceeds this range, large intermetallic compounds are more likely to form during casting, resulting in reduced plasticity.

[0126] When the outer brazing material contains Ti, the Ti content in the outer brazing material is 0.30% by mass or less, preferably 0.10 to 0.20% by mass. Having a Ti content within this range in the outer brazing material makes it easier to achieve the effect of grain coarsening. On the other hand, if the Ti content in the outer brazing material exceeds this range, large intermetallic compounds are more likely to form during casting, resulting in reduced plasticity.

[0127] When the outer brazing material contains Zr, the Zr content in the outer brazing material is 0.30% by mass or less, preferably 0.10 to 0.20% by mass. Having the Zr content in the outer brazing material within this range makes it easier to achieve the grain coarsening effect. On the other hand, if the Zr content in the outer brazing material exceeds this range, large intermetallic compounds are more likely to form during casting, resulting in reduced plastic workability.

[0128] The crystal grain size after brazing is adjusted by utilizing the above-mentioned action, and the effects of the present invention can be fully obtained within the above range.

[0129] The outer brazing material may contain one or more of Na, Sr, and Sb. In the aluminum alloy forming the outer brazing material, Na, Sr, and Sb have the effect of refining the Si particles in the brazing material and improving the fluidity of the brazing material. When the outer brazing material contains Na, the Na content in the outer brazing material is 0.050% by mass or less, preferably 0.005 to 0.040% by mass. When the outer brazing material contains Sr, the Sr content in the outer brazing material is 0.050% by mass or less, preferably 0.005 to 0.040% by mass. When the outer brazing material contains Sb, the Sb content in the outer brazing material is 0.050% by mass or less, preferably 0.005 to 0.040% by mass. The refining effect of Si particles is obtained by having the content of Na, Sr, and Sb in the outer brazing material within the above ranges. On the other hand, if the Na, Sr, and Sb content in the exterior brazing material exceeds the above range, the effect becomes saturated and it is not economical.

[0130] The outer brazing material may contain 0.050% by mass or less of Ag, B, Be, Ca, Cd, Co, Ga, Ge, Hg, In, Li, Mo, Ni, P, Pb, Sn, V, and Y as unavoidable impurities.

[0131] The following manufacturing methods are used to produce the first embodiment of the aluminum alloy brazing sheet and the second embodiment of the aluminum alloy brazing sheet of the present invention. First, an aluminum alloy ingot having the core material composition for the first embodiment of the aluminum alloy brazing sheet and the second embodiment of the aluminum alloy brazing sheet of the present invention is produced, and the aluminum alloy ingot for the core material is made to a predetermined thickness. Next, an aluminum alloy ingot having the cladding material composition (skin material 1, skin material 2, internal brazing material 1, internal brazing material 2, sacrificial anode material A, sacrificial anode material B1, sacrificial anode material B2, outer brazing material) for the first embodiment of the aluminum alloy brazing sheet and the second embodiment of the aluminum alloy brazing sheet of the present invention is produced, and made to a predetermined thickness by hot rolling or the like. Then, if necessary, the aluminum alloy ingot for the core material is homogenized at 450 to 630°C for 1 to 100 hours. Next, the aluminum alloy ingot for the core material and the predetermined aluminum alloy ingot for the cladding material are stacked in a predetermined stacking order, and hot rolling is performed at 400 to 550°C. Next, by cold rolling in one or more passes to a predetermined thickness and, if necessary, intermediate annealing at 250-450°C for 1-24 hours and / or final annealing, an aluminum alloy brazed sheet of the first embodiment of the present invention or an aluminum alloy brazed sheet of the second embodiment of the present invention is obtained.

[0132] The aluminum alloy brazing sheet of the first embodiment of the present invention and the aluminum alloy brazing sheet of the second embodiment of the present invention are processed into a predetermined shape for a heat exchanger component, combined with other heat exchanger components as part of the heat exchanger, and then brazed by brazing heating at a temperature of 580-630°C for 1-10 minutes without the use of flux in an inert gas atmosphere, thereby manufacturing the heat exchanger.

[0133] The first embodiment of the aluminum alloy brazing sheet and the second embodiment of the aluminum alloy brazing sheet of the present invention exhibit excellent brazing properties in brazing in an inert gas atmosphere. The brazing properties of clad plate materials are generally evaluated by the gap-filling test (LWS T 8801). However, this gap-filling test is insufficient to evaluate practical brazing properties where solder inflow and outflow occur between multiple joints, as the fillet is formed and grows from a single point. Therefore, to solve this problem, the inventors developed an "open-mouth overlap test" and evaluated the brazing properties of each test material. The open-mouth overlap test described below is a test method in which, as shown in Figure 1, a test material cut to a predetermined size, for example, 15 mm wide and 25 mm long, and a bare A3003-O plate with a thickness of 1.0 mm cut to a predetermined size, for example, 15 mm wide and 25 mm long, are overlapped so that the sides on which the cladding material 1 and internal brazing material 1 are attached face inward, one side of the bare plate is lifted and a spacer with a diameter of 1.6 mm is inserted, and the bare plate on the opposite side of the spacer and the test material are brought into linear contact, thereby creating a test specimen with a small clearance between the test material and the bare plate, and this test specimen is brazed in a position where the linear contact area between the test material and the bare plate is parallel to gravity. In the brazing heating in the open-mouth overlap test, after assembling the test material into the open-mouth overlap test specimen, it is brazed in a furnace in a nitrogen gas atmosphere without using flux. The brazing heating conditions are as follows: when the test specimen is heated to 400°C or higher, the oxygen concentration in the furnace is controlled to 50 ppm or less and the dew point to -45°C or lower; when the test specimen temperature is 570°C or higher, the oxygen concentration is controlled to 10 ppm or less and the dew point to -60°C or lower, and the target temperature of the test specimen is 600°C. In this open-mouth overlap test, for example, if the breakdown of the oxide film is delayed at the top compared to the bottom in the direction of gravity, a fillet will be formed on the bottom side first, causing the brazing material that would have formed the fillet on the top side to flow out to the bottom side where the fillet is formed. This is an extremely excellent evaluation method that can easily evaluate the inflow and outflow of brazing material in practical products. Therefore, this open-mouth overlap test can appropriately evaluate the practical brazing properties where inflow and outflow of brazing material occurs between multiple joints.

[0134] The present invention will be specifically described below with reference to examples, but the present invention is not limited to the examples shown below. [Examples]

[0135] (Examples and Comparative Examples) Core ingots, internal brazing ingots, and outer ingots having the compositions shown in Table 1 were produced by continuous casting. For the core ingots, the obtained ingots were faceted to a size of 163 mm in length, 163 mm in width, and 27 mm in thickness. For the outer ingots and brazing ingots, the obtained ingots were hot-rolled at 500°C to a thickness of 3 mm, then cold-rolled to the desired thickness, and cut to dimensions of 163 mm in length and 163 mm in width.

[0136] [Table 1]

[0137] The prepared core ingots, internal brazing material ingots, and outer layer ingots were stacked in the combinations shown in Table 2 and subjected to hot rolling and cold rolling to a thickness of 0.6 mm. After that, a final annealing was performed at 360°C by a conventional method to obtain a soft clad sheet material with layers of outer layer 1 / internal brazing material 1 / core material (for Comparative Example 1, internal brazing material 1 / core material). The obtained clad sheet material was used as the test material.

[0138] [Table 2]

[0139] Next, the resulting clad plate material was used to conduct the following overlapping test with open ends. The results are shown in Table 3.

[0140] <Mouth opening overlap test> As shown in Figure 1, a test specimen was prepared by overlapping a test material cut to 15 mm wide and 25 mm long with a bare A3003-O plate with a thickness of 1.0 mm cut to 15 mm wide and 25 mm long, with the sides on which the cladding material 1 and internal brazing material 1 are attached facing inward. A 1.6 mm diameter spacer was inserted by lifting one side of the bare material, and the bare material on the opposite side of the spacer and the test material were brought into linear contact, thereby creating a small clearance between the test material and the bare material. Next, the test material was assembled into a test specimen by overlapping the open pieces. Then, the test specimen was brazed in a furnace in a nitrogen gas atmosphere without using flux, with the linear contact area between the test material and the bare material parallel to gravity. The brazing heating conditions were controlled as follows: when the test specimen was heated to 400°C or higher, the oxygen concentration in the furnace was 50 ppm or less and the dew point was -45°C or lower; when the test specimen temperature was 570°C or higher, the oxygen concentration was 10 ppm or less and the dew point was -60°C or lower, and the final temperature of the test specimen was 600°C. After brazing heating, the fillet shape formed in the minute clearance of the open-mouthed, overlapping test specimens was imaged using X-ray CT. The imaging conditions were a tube voltage of 160kV and a tube current of 100μA, and the entire test specimen was imaged. Figure 2 shows a schematic diagram of the acquired X-ray CT image. The fillet is shown in white, with the left side of Figure 2 being the side under gravity and the right side being the side over gravity. The obtained X-ray CT image was analyzed using ImageJ. The X-ray CT image was binarized to black and white, the gravity direction was set as the x-axis, and the fillet length perpendicular to the x-axis was quantified. Based on the analysis results, a ○× judgment was made for each of the following three indicators. (Indicator 1) Excluding the edges of the image where no fillets exist, if the fillet length was 0, i.e., no fillets were present, it was determined that there was a fillet break (×); otherwise, it was determined that there was no fillet break (〇). (Indicator 2) When the gravity-affected end of the fillet is set to x=0, the minimum fillet length at x=12~13mm is defined as the central part (B), the minimum fillet length at x=22~23mm is defined as the gravity-affected side (C), and the maximum fillet length at x=0~1mm is defined as the gravity-affected side (A). Then, "((B+C) / 2) / A" was defined as the gravity effect coefficient of the fillet length. A larger coefficient means that a uniform fillet was formed against gravity, and a value of 0.35 or higher was judged as (○), and a value less than 0.34 was judged as (×). (Indicator 3) The standard deviation of the fillet length was calculated in the range of x = 0 to 25 mm. A smaller value indicates that a more uniform fillet was formed, and it was judged as ○ if it was 0.6 mm or less, and × if it was greater than 0.6 mm. The evaluation results are shown in Table 3. In the example, all indicators received a "○" rating. In the comparative example, at least one indicator received a "×" rating.

[0141] [Table 3]

[0142] From the above results, it can be seen that the first embodiment of the present invention, having an internal brazing material 1 and a outer layer 1 whose chemical composition is within the specified range of the present invention, exhibits excellent brazing properties in brazing in an inert gas atmosphere without the use of flux. Furthermore, the above results show that having a skin material 1 with a chemical composition within the specified range of the present invention as the outermost layer, and an internal brazing material 1 with a chemical composition within the specified range of the present invention one layer inside it, results in excellent brazing properties when brazing in an inert gas atmosphere without the use of flux. Therefore, it is presumed that the second embodiment of the present invention, an aluminum alloy brazing sheet having a skin material 1 with a chemical composition within the specified range of the present invention as the outermost layer, and an internal brazing material 1 with a chemical composition within the specified range of the present invention one layer inside it, will similarly have excellent brazing properties when brazing in an inert gas atmosphere without the use of flux. Furthermore, the above results show that even when the aluminum alloy brazing sheet of the first embodiment of the present invention or the aluminum alloy brazing sheet of the second embodiment of the present invention has an internal brazing material 2 and a skin material 2 on the side opposite to the internal brazing material 1 and skin material 1 with respect to the core material, and the chemical composition of these materials is within the range specified by the present invention, it exhibits excellent brazing properties when brazed in an inert gas atmosphere without the use of flux.

Claims

1. An aluminum alloy brazing sheet having a core made of pure aluminum or an aluminum alloy, and an internal brazing material 1 and a cladding material 1 clad on at least one side of the core in the order of a cladding material 1 / internal brazing material 1 / core, and used for brazing in an inert gas atmosphere without the use of flux. The internal brazing material 1 is made of an aluminum alloy containing 6.00 to 13.00 mass% Si, more than 0.50 mass% and 4.50 mass% or less Mg, and 0.010 to 0.50 mass% Bi, with the remainder being aluminum and unavoidable impurities. The aforementioned leather material 1 is an aluminum alloy brazing sheet characterized by containing 6.00 to 13.00 mass% of Si and Mg in amounts exceeding 0.050 mass% and 0.50 mass% or less, with a Bi content of 1.00 mass% or less, and the remainder consisting of aluminum and unavoidable impurities.

2. Furthermore, the structure consists of a skin material 1 / internal brazing material 1 / core material / sacrificial anode material A, with the sacrificial anode material A cladding to the other side of the core material. The aluminum alloy brazing sheet according to claim 1, characterized in that the sacrificial anode material A contains one or more of the following: 5.00 mass% or less of Si, 1.50 mass% or less of Fe, 2.00 mass% or less of Cu, 2.00 mass% or less of Mn, 3.00 mass% or less of Mg, 6.00 mass% or less of Zn, 0.30 mass% or less of Cr, 0.30 mass% or less of Ti, and 0.30 mass% or less of Zr, with the remainder being aluminum and unavoidable impurities.

3. Furthermore, the structure consists of a leather material 1 / internal brazing material 1 / core material / outer brazing material, with the outer brazing material cladding to the other side of the core material. The aluminum alloy brazing sheet according to claim 1, characterized in that the outer brazing material contains 6.00 to 13.00 mass% of Si, and further contains one or more of the following: 1.00 mass% or less of Fe, 2.00 mass% or less of Cu, 2.00 mass% or less of Mn, 4.50 mass% or less of Mg, 6.00 mass% or less of Zn, 0.50 mass% or less of Bi, 0.30 mass% or less of Cr, 0.30 mass% or less of Ti, and 0.30 mass% or less of Zr, with the remainder being an aluminum alloy consisting of aluminum and unavoidable impurities.

4. Furthermore, the layers are arranged in the order of outer material 1 / inner brazing material 1 / core material / sacrificial anode material A / outer brazing material, with the outer brazing material cladding to the side of the sacrificial anode material A opposite to the core material. The aluminum alloy brazing sheet according to claim 2, characterized in that the outer brazing material contains 6.00 to 13.00 mass% of Si, and further contains one or more of the following: 1.00 mass% or less of Fe, 2.00 mass% or less of Cu, 2.00 mass% or less of Mn, 4.50 mass% or less of Mg, 6.00 mass% or less of Zn, 0.50 mass% or less of Bi, 0.30 mass% or less of Cr, 0.30 mass% or less of Ti, and 0.30 mass% or less of Zr, with the remainder being aluminum and unavoidable impurities.

5. Furthermore, the sacrificial anode material A has an internal brazing material 2 and a cladding material 2 cladding to the side of the sacrificial anode material A opposite to the core material, in the order of skin material 1 / internal brazing material 1 / core material / sacrificial anode material A / internal brazing material 2 / skin material 2. The internal brazing material 2 is made of an aluminum alloy containing 6.00 to 13.00 mass% Si, more than 0.50 mass% and 4.50 mass% or less Mg, and 0.010 to 0.50 mass% Bi, with the remainder being aluminum and unavoidable impurities. The aluminum alloy brazing sheet according to claim 2, characterized in that the leather material 2 contains 6.00 to 13.00 mass% of Si and Mg in an amount greater than 0.050 mass% and less than or equal to 0.50 mass%, has a Bi content of 1.00 mass% or less, and is made of an aluminum alloy with the remainder being aluminum and unavoidable impurities.

6. Furthermore, the core material has an internal brazing material 2 and an internal brazing material 2 cladding to the other side of the core material in the order of outer material 1 / internal brazing material 1 / core material / internal brazing material 2 / outer material 2. The internal brazing material 2 is made of an aluminum alloy containing 6.00 to 13.00 mass% Si, more than 0.50 mass% and 4.50 mass% or less Mg, and 0.010 to 0.50 mass% Bi, with the remainder being aluminum and unavoidable impurities. The aluminum alloy brazing sheet according to claim 1, characterized in that the leather material 2 contains 6.00 to 13.00 mass% of Si and Mg in an amount greater than 0.050 mass% and less than or equal to 0.50 mass%, has a Bi content of 1.00 mass% or less, and is made of an aluminum alloy with the remainder being aluminum and unavoidable impurities.

7. An aluminum alloy brazing sheet having a core made of pure aluminum or an aluminum alloy, and a sacrificial anode material B1, internal brazing material 1, and core material B1 clad on at least one side of the core in the order of outer material 1 / internal brazing material 1 / sacrificial anode material B1 / core material, and used for brazing in an inert gas atmosphere without using flux. The internal brazing material 1 is made of an aluminum alloy containing 6.00 to 13.00 mass% Si, more than 0.50 mass% and 4.50 mass% or less Mg, and 0.010 to 0.50 mass% Bi, with the remainder being aluminum and unavoidable impurities. The aforementioned coating material 1 contains 6.00 to 13.00 mass% of Si and more than 0.050 mass% and 0.50 mass% or less of Mg, with a Bi content of 1.00 mass% or less, and is made of an aluminum alloy consisting of the remainder being aluminum and unavoidable impurities. The sacrificial anode material B1 is an aluminum alloy brazing sheet characterized by containing one or more of the following: 5.00 mass% or less of Si, 1.50 mass% or less of Fe, 2.00 mass% or less of Cu, 2.00 mass% or less of Mn, 3.00 mass% or less of Mg, 6.00 mass% or less of Zn, 0.30 mass% or less of Cr, 0.30 mass% or less of Ti, and 0.30 mass% or less of Zr, with the remainder being aluminum and unavoidable impurities.

8. Furthermore, the structure consists of a skin material 1 / internal brazing material 1 / sacrificial anode material B1 / core material / sacrificial anode material B2, with the sacrificial anode material B2 cladding to the other side of the core material. The aluminum alloy brazing sheet according to claim 7, characterized in that the sacrificial anode material B2 contains one or more of the following: 5.00 mass% or less of Si, 1.50 mass% or less of Fe, 2.00 mass% or less of Cu, 2.00 mass% or less of Mn, 3.00 mass% or less of Mg, 6.00 mass% or less of Zn, 0.30 mass% or less of Cr, 0.30 mass% or less of Ti, and 0.30 mass% or less of Zr, with the remainder being aluminum and unavoidable impurities.

9. Furthermore, the layers are arranged in the order of outer material 1 / inner brazing material 1 / sacrificial anode material B1 / core material / outer brazing material, with the outer brazing material cladding to the other side of the core material. The aluminum alloy brazing sheet according to claim 7, characterized in that the outer brazing material contains 6.00 to 13.00 mass% of Si, and further contains one or more of the following: 1.00 mass% or less of Fe, 2.00 mass% or less of Cu, 2.00 mass% or less of Mn, 4.50 mass% or less of Mg, 6.00 mass% or less of Zn, 0.50 mass% or less of Bi, 0.30 mass% or less of Cr, 0.30 mass% or less of Ti, and 0.30 mass% or less of Zr, with the remainder being aluminum and unavoidable impurities.

10. Furthermore, the structure consists of a skin material 1 / internal brazing material 1 / sacrificial anode material B1 / core material / sacrificial anode material B2 / outer brazing material, with the outer brazing material cladding to the side of the sacrificial anode material B2 opposite to the core material. The aluminum alloy brazing sheet according to claim 8, characterized in that the outer brazing material contains 6.00 to 13.00 mass% of Si, and further contains one or more of the following: 1.00 mass% or less of Fe, 2.00 mass% or less of Cu, 2.00 mass% or less of Mn, 4.50 mass% or less of Mg, 6.00 mass% or less of Zn, 0.50 mass% or less of Bi, 0.30 mass% or less of Cr, 0.30 mass% or less of Ti, and 0.30 mass% or less of Zr, with the remainder being aluminum and unavoidable impurities.

11. Furthermore, the structure is arranged in the order of skin material 1 / internal brazing material 1 / sacrificial anode material B1 / core material / sacrificial anode material B2 / internal brazing material 2 / skin material 2, with the internal brazing material 2 and skin material 2 cladding to the side of the sacrificial anode material B2 opposite to the core material. The internal brazing material 2 is made of an aluminum alloy containing 6.00 to 13.00 mass% Si, more than 0.50 mass% and 4.50 mass% or less Mg, and 0.010 to 0.50 mass% Bi, with the remainder being aluminum and unavoidable impurities. The aluminum alloy brazing sheet according to claim 8, characterized in that the leather material 2 contains 6.00 to 13.00 mass% of Si and Mg in an amount greater than 0.050 mass% and less than or equal to 0.50 mass%, has a Bi content of 1.00 mass% or less, and is made of an aluminum alloy with the remainder being aluminum and unavoidable impurities.

12. Furthermore, the core material has an internal brazing material 2 and a cladding material 2 cladding to the other side of the core material, in the order of: outer material 1 / internal brazing material 1 / sacrificial anode material B1 / core material / internal brazing material 2 / outer material 2. The internal brazing material 2 is made of an aluminum alloy containing 6.00 to 13.00 mass% Si, more than 0.50 mass% and 4.50 mass% or less Mg, and 0.010 to 0.50 mass% Bi, with the remainder being aluminum and unavoidable impurities. The aluminum alloy brazing sheet according to claim 7, characterized in that the leather material 2 contains 6.00 to 13.00 mass% of Si and Mg in an amount greater than 0.050 mass% and less than or equal to 0.50 mass%, has a Bi content of 1.00 mass% or less, and is made of an aluminum alloy with the remainder being aluminum and unavoidable impurities.

13. The aluminum alloy brazing sheet according to any one of claims 1 to 12, characterized in that the core material is an aluminum alloy containing one or more of the following: 1.50% by mass or less of Si, 1.50% by mass or less of Fe, 2.00% by mass or less of Cu, 2.00% by mass or less of Mn, 3.00% by mass or less of Mg, 3.00% by mass or less of Zn, 0.50% by mass or less of Bi, 0.30% by mass or less of Cr, 0.30% by mass or less of Ti, and 0.30% by mass or less of Zr, with the remainder being aluminum and unavoidable impurities.

14. The aluminum alloy brazing sheet according to any one of claims 5, 6, 11, or 12, characterized in that at least one of the internal brazing material 1 and the internal brazing material 2 further contains one or more of the following: 1.00 mass% or less of Fe, 2.00 mass% or less of Cu, 2.00 mass% or less of Mn, 6.00 mass% or less of Zn, 0.30 mass% or less of Cr, 0.30 mass% or less of Ti, and 0.30 mass% or less of Zr.

15. The aluminum alloy brazing sheet according to any one of claims 5, 6, 11, or 12, characterized in that at least one of the skin material 1 and the skin material 2 further contains one or more of the following: 1.00% by mass or less of Fe, 2.00% by mass or less of Cu, 2.00% by mass or less of Mn, 6.00% by mass or less of Zn, 0.30% by mass or less of Cr, 0.30% by mass or less of Ti, and 0.30% by mass or less of Zr.

16. The aluminum alloy brazing sheet according to any one of claims 5, 6, 11, or 12, characterized in that the thickness of at least one of the leather material 1 and the leather material 2 is 5.0 μm or more.

17. The aluminum alloy brazing sheet according to any one of claims 5, 6, 11, or 12, characterized in that the thickness of at least one of the internal brazing material 1 and the internal brazing material 2 is 15.0 μm or more.

18. The aluminum alloy brazing sheet according to any one of claims 1 to 17, characterized in that the average Mg concentration in the thickness direction of the internal brazing material 1 and the outer material 1 exceeds 0.50% by mass, and the average Bi concentration in the thickness direction of the internal brazing material 1 and the outer material 1 exceeds 0.050% by mass.

19. The aluminum alloy brazing sheet according to any one of claims 5, 6, 11, or 12, characterized in that the average Mg concentration in the thickness direction of the internal brazing material 2 and the outer material 2 exceeds 0.50% by mass, and the average Bi concentration in the thickness direction of the internal brazing material 2 and the outer material 2 exceeds 0.050% by mass.

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