ALUMINUM ALLOY BOLD SHEET AND METHOD FOR PRODUCING THE SAME

Abstract

Aluminium alloy brazing sheet, used for brazing in an inert gas atmosphere without the use of a flux, with: a brazing alloy material that is plated onto at least one side surface of a core material, where the core material is aluminum or an aluminum alloy core material containing one or two or more of Fe of 1.50 wt% or less, Si of 1.50 wt% or less, Cu of 2.00 wt% or less, Mn of 2.00 wt% or less, Zn of 3.00 wt% or less, Cr of 0.30 wt% or less, Ti of 0.30 wt% or less, Zr of 0.30 wt% or less, In of 0.10 wt% or less and Sn of 0.10 wt% or less, the remainder being aluminium and unavoidable impurities, is formed, wherein the brazing alloy material is an aluminum alloy brazing alloy material having Si of 4.00 to 13.00 wt% and one or two or more of Mg of more than 0.03 wt% and 3.00 wt% or less, Li of more than 0.03 wt% and 3.00 wt% or less, and Ca of more than 0.03 wt% and 3.00 wt% or less, the remainder being aluminum and unavoidable impurities, wherein an oxide is formed on a surface of the aluminium alloy brazing sheet by brazing heating, which has an oxide of one or two or more of Mg, Li and Ca and has a volume change ratio of 0.990 or less to a surface oxide film formed before brazing heating, and an atomic molar ratio of Mg, Ni and Ca to Al in the oxide formed on the surface of the aluminium alloy brazing sheet before brazing heating is 0.5 or less.

Description

TECHNICAL AREA

[0001] The present invention relates to an aluminium alloy brazing sheet used for brazing aluminium or an aluminium alloy in an inert gas atmosphere without the use of a flux, and to a method for producing the same. BACKGROUND

[0002] Brazing is widely used as a method for joining aluminum products that have a number of tiny connecting sections, such as heat exchangers and machine components made of aluminum. To perform a brazing joint on aluminum or an aluminum alloy, it is essential to break up any oxide film covering its surface and expose the molten brazing material, which is then wetted with a base material or a similarly molten brazing material. Methods for breaking up the oxide film are largely divided into those using a flux in a nitrogen gas furnace and those using a vacuum furnace that do not, and both have been put into practical use.

[0003] In processes using a nitrogen gas furnace and a flux, the flux reacts with the oxide film during brazing heating, breaking it up. However, these processes suffer from increased flux costs and the additional step of applying the flux. Furthermore, uneven flux application can lead to defective brazing. In contrast, processes using a vacuum furnace without a flux utilize a brazing material formed from an Al-Si-Mg-based alloy. The Mg in the brazing material is vaporized by heating in a vacuum, breaking up the oxide film on the material's surface. However, these processes require expensive vacuum heating equipment.These processes also suffer from the problem of high maintenance costs required to remove adhering Mg, as vaporized Mg sticks to the inside of the furnace. For this reason, there is an increasing need to perform compounding in a nitrogen gas furnace without the use of a flux.

[0004] To meet the need described above, JP 2013-215797A, for example, proposes incorporating Mg into the brazing material to enable surface bonding. Furthermore, JP 4547032B1 proposes incorporating Mg into the core material and diffusing Mg into the brazing material during brazing heating to enable fillet formation in a simple lamellar / tube joint. JP 4547032B1 also discloses that good fluxless brazing can be achieved by limiting the equivalent circle diameter and the number of Si particles contained in the brazing material and by bringing the brazing material and the brazing target material into close contact. However, it is impossible for these methods to form a sufficient fillet in a gap-filling joint without applying a flux.In these processes, the oxide film is broken down into particles containing magnesium. Subsequently, a difference in thermal expansion between the molten brazing material and the oxide film, or an external force such as a flow of filler metal, causes wetting, thus exposing a new surface of the molten brazing material. For this reason, these processes result in the formation of a distorted fillet accompanied by a break in the fillet.

[0005] Furthermore, JP 2004-358519A proposes that it is effective to suppress the thickness of an MgO film present on the oxide film prior to brazing. However, JP 2004-358519A states that with brazing materials containing Mg of 0.1 wt% or more, a MgO-based film partially forms during brazing in a practical joint, preventing the formation of a fillet and causing a fillet break. In contrast, JP H11-285817A proposes a method for removing an MgO-based film and enabling fluxless brazing by performing acid cleaning on brazing materials containing Mg of 0.05 wt% or more prior to brazing. However, the method is not able to sufficiently suppress the formation of an MgO-based film during brazing, as JP 2013 - 215 797 A.

[0006] JP 2017 - 074 609 A proposes a brazing sheet in which oxide particles containing an X element (X being Mg, Li, Be, Ca, Ce, La, Y, and Zr) exhibiting a volume change ratio of 0.99 or less relative to the oxide film before brazing are formed on the surface. Although this structure offers improved brazing properties for a more practical joint with a gap, an actual heat exchanger will have a larger gap, and the brazing properties of the structure may be insufficient.

[0007] EP 3 323 901 A1 and EP 3 205 440 A1 reveal further aluminium alloy brazing sheets. SUMMARY OF THE INVENTION PROBLEM TO BE SOLVED BY THE INVENTION

[0008] An object of the present invention is to provide an aluminium alloy brazing sheet which, even in the case of having a large gap, exhibits excellent brazing properties and a close contact area between components of a heat exchanger when brazing in an inert gas atmosphere without the use of a flux, and a method for producing the same. MEANS TO SOLVE THE PROBLEM

[0009] The problem described above is solved by the present invention, which is described below.

[0010] In particular, the present invention (1) provides an aluminium alloy brazing sheet for brazing in an inert gas atmosphere without the use of a flux, comprising: a brazing alloy material that is plated onto at least one side surface of a core material, in which the core material is formed from aluminium or an aluminium alloy core material comprising one or two or more of Fe of 1.50 wt% or less, Si of 1.50 wt% or less, Cu of 2.00 wt% or less, Mn of 2.00 wt% or less, Zn of 3.00 wt% or less, Cr of 0.30 wt% or less, Ti of 0.30 wt% or less, Zr of 0.30 wt% or less, In of 0.10 wt% or less and Sn of 0.10 wt% or less, the remainder being aluminium and unavoidable impurities, wherein the brazing alloy material is an aluminum alloy brazing alloy material having Si of 4.00 to 13.00 wt% and one or two or more of Mg of more than 0.03 wt% and 3.00 wt% or less, Li of more than 0.03 wt% and 3.00 wt% or less and Ca of more than 0.03 wt% and 3.00 wt% or less, the remainder being aluminum and unavoidable impurities, wherein an oxide is formed on a surface of the aluminium alloy brazing sheet by brazing heating, which contains one or two or more of Mg, Li and Ca and has a volume change ratio of 0.990 or less to a surface oxide film formed before brazing heating, and an atomic molar ratio of Mg, Li and Ca to Al in the oxide formed on the surface of the aluminium alloy brazing sheet before brazing heating is 0.5 or less.

[0011] The present invention (2) provides the aluminium alloy brazing sheet according to (1), wherein the aluminium alloy brazing sheet is a two-layer material in which the brazing material is plated onto a side surface of the core material.

[0012] The present invention (3) provides the aluminium alloy brazing sheet according to (1), wherein the aluminium alloy brazing sheet is a three-layer material in which the brazing material is plated onto each of the two side surfaces of the core material.

[0013] The present invention (4) provides the aluminium alloy brazing sheet according to (1), in which the aluminum alloy brazing sheet is a three-layer material in which the brazing material is plated onto one side surface of the core material and a plating material is plated onto the other side surface of the core material, and the plating material is an aluminum alloy plating material formed from aluminum or an aluminum alloy having Zn of 6.00 wt% or less, the remainder being aluminum and unavoidable impurities.

[0014] The present invention (5) provides the aluminium alloy brazing sheet according to one of (1) to (4), wherein the core material further comprises one or two or more of Mg of 3.00 wt% or less, Li of 3.00 wt% or less and Ca of 3.00 wt% or less.

[0015] The present invention (6) provides the aluminium alloy brazing sheet according to (1) to (5), wherein the core material further comprises Bi of 1.00 wt% or less.

[0016] The present invention (7) provides the aluminium alloy brazing sheet according to (1) to (6), wherein the brazing material further comprises Bi of 1.00 wt% or less.

[0017] The present invention (8) provides the aluminium alloy brazing sheet according to one of (1) to (7), wherein the brazing material further comprises one or two or more of Na of 0.05 wt% or less, Sr of 0.05 wt% or less, Sb of 0.05 wt% or less, Zn of 8.00 wt% or less, Cu of 4.00 wt% or less, Fe of 1.00 wt% or less, Mn of 1.00 wt% or less, Cr of 0.30 wt% or less, Ti of 0.30 wt% or less, Zr of 0.30 wt% or less, In of 0.10 wt% or less and Sn of 0.10 wt% or less.

[0018] The present invention (9) provides the aluminium alloy brazing sheet according to one of (4) to (8), wherein the cladding material further comprises one or two or more of Mn of 2.00 wt% or less, Mg of 3.00 wt% or less, Si of 5.00 wt% or less, Fe of 1.50 wt% or less, Cu of 1.00 wt% or less, Ti of 0.30 wt% or less, Zr of 0.30 wt% or less, Cr of 0.30 wt% or less, In of 0.10 wt% or less and Sn of 0.10 wt% or less.

[0019] The present invention (10) provides the aluminium alloy brazing sheet according to one of (1) to (9) wherein the oxide formed on a brazing material surface of the aluminium alloy brazing sheet has a thickness of 50 nm or less.

[0020] The present invention (11) provides a method for producing an aluminum alloy brazing sheet, comprising at least hot working and cold working for (1) a stacked structure obtained by stacking a brazing material ingot and a core material ingot in that order; (2) a stacked structure obtained by stacking a brazing material ingot, a core material ingot, and a brazing material ingot in that order; or (3) a stacked structure obtained by stacking a brazing material ingot, a core material ingot, and a cladding material in that order, for producing an aluminum alloy brazing sheet, wherein the core material ingot is formed from aluminium or an aluminium alloy comprising one or two or more of Fe of 1.50 wt% or less, Si of 1.50 wt% or less, Cu of 2.00 wt% or less, Mn of 2.00 wt% or less, Zn of 3.00 wt% or less, Cr of 0.30 wt% or less, Ti of 0.30 wt% or less, Zr of 0.30 wt% or less, In of 0.10 wt% or less and Sn of 0.10 wt% or less, the remainder being aluminium and unavoidable impurities, the brazing ingot is formed from an aluminum alloy having Si of 4.00 to 13.00 wt% and one or two or more of Mg of more than 0.03 wt% and 3.00 wt% or less, Li of more than 0.03 wt% and 3.00 wt% or less and Ca of more than 0.03 wt% and 3.00 wt% or less, the remainder being aluminum and unavoidable impurities, the plating material ingot is formed from aluminium or an aluminium alloy having a Zn content of 6.00 wt% or less, the remainder being aluminium and unavoidable impurities, and an intermediate annealing treatment, a final annealing treatment, or an annealing treatment is carried out, wherein the intermediate annealing treatment is carried out between rolling passes during cold working to heat the stacked structure at 250 to 450°C for one hour or more in an atmosphere controlled to have an oxygen concentration of 10,000 ppm or less and a dew point of 20°C or less, and the final annealing treatment is carried out after a final pass of cold working to heat the stacked structure at 250 to 450°C for one hour or more in an atmosphere controlled to have an oxygen concentration of 10.The annealing treatment is carried out both between rolling passes during cold working and after the last pass of cold working to heat the stacked structure at 250 to 450°C for one hour or more in an atmosphere regulated to have an oxygen concentration of 10,000 ppm or less and a dew point of 20°C or less.

[0021] The present invention (12) provides the method for producing an aluminium alloy brazing sheet according to (11), wherein the core material ingot further comprises one or two or more of Mg of 3.00 wt% or less, Li of 3.00 wt% or less and Ca of 3.00 wt% or less.

[0022] The present invention (13) provides the method for producing an aluminium alloy brazing sheet according to (11) or (12), wherein one of the core material ingot and the brazing material ingot further comprises Bi of 1.00 wt% or less.

[0023] The present invention (14) provides a method for producing an aluminium alloy brazing sheet according to one of (11) to (13), wherein the brazing material ingot further comprises one or two or more of Na of 0.05 wt% or less, Sr of 0.05 wt% or less, Sb of 0.05 wt% or less, Zn of 8.00 wt% or less, Cu of 4.00 wt% or less, Fe of 1.00 wt% or less, Mn of 1.00 wt% or less, Cr of 0.30 wt% or less, Ti of 0.30 wt% or less, Zr of 0.30 wt% or less, In of 0.10 wt% or less and Sn of 0.10 wt% or less.

[0024] The present invention (15) provides a method for producing an aluminium alloy brazing sheet according to one of (11) to (14), wherein the cladding material ingot further comprises one or two or more of Mn of 2.00 wt% or less, Mg of 3.00 wt% or less, Si of 5.00 wt% or less, Fe of 1.50 wt% or less, Cu of 1.00 wt% or less, Ti of 0.30 wt% or less, Zr of 0.30 wt% or less, Cr of 0.30 wt% or less, In of 0.10 wt% or less and Sn of 0.10 wt% or less.

[0025] The present invention (16) provides a method for producing an aluminium alloy brazing sheet according to (11) to (15), wherein a brazing material surface of a cladding material is subjected to etching using one or both an aqueous acid solution and an aqueous basic solution, the etching being carried out after the intermediate annealing treatment, if the intermediate annealing treatment is carried out, after the final annealing treatment, if the final annealing treatment is carried out, and at one or both times after the intermediate annealing treatment and after the final annealing treatment, if both the intermediate annealing treatment and the final annealing treatment are carried out. EFFECTS OF THE INVENTION

[0026] The present invention relates to an aluminium alloy brazing sheet which exhibits excellent brazing properties when brazed in an inert gas atmosphere without the use of a flux, and to a method for producing the same. BRIEF EXPLANATION OF DRAWINGS Fig. Figure 1 is a diagram showing the arrangement of a gap-filling test piece with examples and comparison examples. FORMS OF EXECUTION OF THE INVENTION

[0027] During brazing, Mg, Li, and Ca break up a film-like oxide that forms on the surface of a brazing material, effectively exposing a new surface of the molten brazing material. Furthermore, because Mg, Li, and Ca have a lower oxide formation energy than Al, they reduce the film-like oxide, which is predominantly Al, during brazing and form a particulate oxide containing Mg, Li, and Ca. Specifically, because the brazing material of the brazing sheet contains one or more or more elements of Mg, Li, and Ca in amounts greater than 0.03% by mass, Mg, Li, and Ca diffuse sufficiently into the surface layer of the mating material (for example, a 3003 material) to which the brazing sheet is attached, oxide particles containing one or more or more elements of Mg, Li, and Ca are formed in the 3003 material serving as the mating material.This causes a change in the volume of the oxide on the surface of the mating material, and good brazing properties are achieved even in a joint that has a large gap.

[0028] An aluminum alloy brazing sheet according to the present invention is an aluminum alloy brazing sheet used for brazing in an inert gas atmosphere without the use of a flux, comprising: a hard solder material that is plated onto at least one side surface of the core material, in which the core material is formed from aluminium or an aluminium alloy core material comprising one or two or more of Fe of 1.50 wt% or less, Si of 1.50 wt% or less, Cu of 2.00 wt% or less, Mn of 2.00 wt% or less, Zn of 3.00 wt% or less, Cr of 0.30 wt% or less, Ti of 0.30 wt% or less, Zr of 0.30 wt% or less, In of 0.10 wt% or less and Sn of 0.10 wt% or less, the remainder being aluminium and unavoidable impurities, wherein the brazing alloy material is an aluminum alloy brazing alloy containing one or two or more of Si from 4.00 to 13.00 wt%, Mg from more than 0.03 wt% and 3.00 wt% or less, Li from more than 0.03 wt% and 3.00 wt% or less, and Ca from more than 0.03 wt% and 3.00 wt% or less, the remainder being aluminum and unavoidable impurities, wherein an oxide is formed on a surface of the aluminium alloy brazing sheet by brazing heating, which has an oxide of one or two or more of Mg, Li and Ca and has a volume change ratio of 0.990 or less to a surface oxide film formed before brazing heating, and an atomic molar ratio of Mg, Li and Ca to Al in the oxide formed on the surface of the aluminium alloy brazing sheet before brazing heating is 0.5 or less.

[0029] The aluminum alloy brazing sheet according to the present invention is an aluminum alloy brazing sheet used for brazing in an inert gas atmosphere without the use of a flux. The aluminum alloy brazing sheet according to the present invention is a cladding material in which a brazing material having a chemical composition as described below is cladding onto at least one side surface of a core material having a chemical composition as described below.The aluminum alloy brazing sheet according to the present invention is: (1) a two-layer material in which a brazing material is plated onto one side surface of a core material; (2) a three-layer material in which a brazing material is plated onto each of the side surfaces of a core material; or (3) a three-layer material in which a brazing material is plated onto one side surface of a core material and a plating material is plated onto the other side surface of the core material.

[0030] The core material of the aluminum alloy brazing sheet according to the present invention is formed from aluminum or an aluminum alloy core material comprising one or two or more of Fe of 1.50 wt% or less, Si of 1.50 wt% or less, Cu of 2.00 wt% or less, Mn of 2.00 wt% or less, Zn of 3.00 wt% or less, Cr of 0.30 wt% or less, Ti of 0.30 wt% or less, Zr of 0.30 wt% or less, In of 0.10 wt% or less and Sn of 0.10 wt% or less, the remainder being aluminum and unavoidable impurities.

[0031] If the core material is made of aluminium, the purity of the aluminium is not particularly limited, but is preferably 99.0 wt% or more, and particularly preferably 99.5 wt% or more.

[0032] In the aluminum alloy that forms the core material, iron (Fe) contributes to improved strength. If the core material contains Fe, the Fe content is 1.50 wt% or less, preferably 0.10 to 0.70 wt%, and particularly preferably 0.20 to 0.60 wt%. With an Fe content in the core material within the range described above, the strength of the core material increases. Conversely, if the Fe content in the core material exceeds the range described above, its corrosion resistance decreases, and large compounds are easily formed.

[0033] In the aluminum alloy that forms the core material, silicon (Si) contributes to improved strength. If the core material contains Si, the Si content in the core material is 1.50 wt% or less, preferably 0.10 to 1.00 wt%, and particularly preferably 0.30 to 0.75 wt%. With a Si content in the core material that falls within the range described above, the strength of the core material increases. Conversely, if the Si content in the core material exceeds the range described above, its melting point becomes too low, local melting occurs during brazing, and the core material is deformed, resulting in a decrease in corrosion resistance.

[0034] In the aluminum alloy that forms the core material, copper contributes to improved strength and potential matching. If the core material contains copper, the copper content in the core material is 2.00 wt% or less, preferably 0.10 to 1.00 wt%, and particularly preferably 0.15 to 0.80 wt%. With a copper content in the core material within the range described above, the strength of the core material increases. Conversely, if the copper content in the core material exceeds the range described above, boundary corrosion readily occurs, and the melting point becomes too low.

[0035] In the aluminum alloy that forms the core material, manganese (Mn) contributes to improved strength and potential matching. If the core material contains Mn, the Mn content is 2.00 wt% or less, preferably 0.30 to 1.80 wt%, and particularly preferably 0.30 to 1.50 wt%. With a Mn content in the core material within the range described above, the strength of the core material increases, and the potential matching effect is achieved. Conversely, if the Mn content in the core material exceeds the range described above, cracks readily occur during rolling of the material.

[0036] In the aluminum alloy forming the core material, zinc (Zn) contributes to potential matching. If the core material contains zinc, the zinc content is 3.00 wt% or less, preferably 0.50 to 3.00 wt%, and particularly preferably 1.50 to 3.00 wt%. Potential matching is achieved with a zinc content in the core material within the range described above. Conversely, if the zinc content in the core material exceeds the range described above, the natural electrode potential becomes too low, and the corrosion resistance decreases.

[0037] In the aluminum alloy forming the core material, chromium improves strength through solution hardening and precipitates Al-Cr-based micro-compounds, thus contributing to grain coarsening after brazing. The chromium content in the core material is 0.30 wt% or less, and preferably 0.10 to 0.20 wt%. With a chromium content in the core material within the range described above, the core material's strength is improved. Conversely, if the chromium content in the core material exceeds the range described above, large intermetallic compounds readily form during casting, and machinability is reduced.

[0038] In the aluminum alloy forming the core material, titanium improves strength through solution hardening and is distributed in layers to form a high-potential layer and a low-potential layer within the core material. This structure changes the corrosion pattern from pitting to layered corrosion, resulting in improved corrosion resistance. The titanium content in the core material is 0.30 wt% or less, preferably 0.10 to 0.20 wt%, and particularly preferably 0.12 to 0.18 wt%. With a titanium content in the core material within the range described above, the core material's strength and corrosion resistance are improved. Conversely, if the titanium content in the core material exceeds the range described above, large intermetallic compounds readily form during casting, and machinability is reduced.

[0039] In the aluminum alloy forming the core material, Zr improves strength through solution hardening and precipitates Al-Zr-based micro-compounds, thus promoting grain coarsening after brazing. The Zr content in the core material is 0.30 wt% or less, and preferably 0.10 to 0.20 wt%. With a Zr content in the core material within the range described above, the core material's strength is improved, and the grain coarsening effect after brazing is achieved. Conversely, if the Zr content in the core material exceeds the range described above, large intermetallic compounds readily form during casting, and machinability is reduced.

[0040] In the aluminum alloy that forms the core material, In contributes to potential matching. If the core material contains In, the In content in the core material is 0.10 wt% or less, and preferably 0.01 to 0.03 wt%. With an In content in the core material that falls within the range described above, the potential matching effect is achieved. Conversely, if the In content in the core material exceeds the range described above, its natural electrode potential becomes too low, and its corrosion resistance decreases.

[0041] In the aluminum alloy that forms the core material, tin (Sn) contributes to potential matching. If the core material contains tin, the tin content is 0.10 wt% or less, and preferably 0.01 to 0.10 wt%. With an tin content in the core material within the range described above, the potential matching effect is achieved. Conversely, if the tin content in the core material exceeds the range described above, the natural electrode potential becomes too low, and the corrosion resistance decreases.

[0042] The core material may contain bi. In the aluminum alloy forming the core material, bi acts to suppress a decrease in the bi concentration of the brazing alloy when the brazing alloy melts during brazing heating and some of the core material melts, and exhibits the effect of reducing the surface tension of the molten Al-Si brazing alloy filler metal. If the core material contains bi, the bi content in the core material is 1.00 wt% or less, and preferably 0.10 to 1.00 wt%. The bi content in the core material, falling within the range described above, produces the effect of melting into the brazing alloy and reducing the surface tension. On the other hand, if the bi content in the core material exceeds the range described above, rolling the material becomes difficult.

[0043] The core material may contain one, two, or more of Mg, Li, and Ca. If the core material contains Mg, the Mg content in the core material is 3.00 wt% or less, and preferably 0.10 to 1.80 wt%. If the core material contains Li, the Li content in the core material is 3.00 wt% or less, and preferably 0.10 to 1.80 wt%. If the core material contains Ca, the Ca content in the core material is 3.00 wt% or less, and preferably 0.10 to 1.80 wt%. With the Mg, Li, or Ca content in the core material falling within the range described above, the Mg, Li, or Ca acts in such a way as to suppress a decrease in the Mg, Li, or Ca concentration of the brazing material when the brazing material is melted and some of the core material melts during brazing heating. Accordingly, the volume change ratio of an oxide formed by oxidation of Mg, Li, or Ca on the surface of the brazing material is 0.990 or less, and the oxide film breaking action of the brazing sheet or mating material containing Mg, Li, and Ca is improved, resulting in excellent brazing properties.On the other hand, if the Mg, Li, or Ca content in the core material exceeds the range described above, the melting point of the core material decreases too much, and local melting occurs in the core material during brazing. This causes deformation of the core material, erosion of the core material with the molten brazing filler metal, and reduces the brazed joint properties and / or corrosion resistance.

[0044] The core material may contain Ag, B, Be, Cd, Co, Ga, Ge, Mo, Na, Ni, P, Pb, Sr, V, Hg and Y at 0.05 wt% or less as unavoidable impurities.

[0045] The brazing material of the aluminum alloy brazing sheet according to the present invention is an aluminum alloy brazing material comprising: (i) Si from 4.0 to 13.0 wt%; and (ii) one or two or more of Mg of more than 0.03 wt% and 3.00 wt% or less, Li of more than 0.03 wt% and 3.00 wt% or less and Ca of more than 0.03 wt% and 3.00 wt% or less, the remainder being aluminium and unavoidable impurities.

[0046] The brazing alloy contains silicon as an essential element. The silicon content in the brazing alloy is 4.00 to 13.00 wt%, and particularly preferably 4.50 to 12.00 wt%. With a silicon content in the brazing alloy within the range described above, a sufficient liquid phase, necessary for a brazed joint, is achieved. Conversely, if the silicon content in the brazing alloy is lower than the range described above, the amount of liquid phase is insufficient. A silicon content exceeding the range described above readily leads to cracking during the manufacturing process and causes difficulties in producing the brazing sheet.

[0047] The brazing alloy contains one or two or more of Mg, Li and Ca.

[0048] If the brazing alloy contains Mg, the Mg content in the brazing alloy exceeds 0.03 wt% and is 3.00 wt% or less, preferably 0.10 to 1.80 wt%, and particularly preferably 0.60 to 1.20 wt%. If the brazing alloy contains Li, the Li content in the brazing alloy exceeds 0.03 wt% and is 3.00 wt% or less, preferably 0.04 to 1.80 wt%, and particularly preferably 0.10 to 1.80 wt%. If the brazing alloy contains Ca, the Ca content in the brazing alloy exceeds 0.03 wt% and is 3.00 wt% or less, preferably 0.05 to 1.80 wt%, and particularly preferably 0.10 to 1.80 wt%.With a Mg, Li, or Ca content in the brazing material that falls within the range described above, the volume change ratio of an oxide formed by the oxidation of Mg, Li, or Ca during brazing heating is set to 0.990 or less. This improves the effect of oxide film breakup on the brazing sheet or mating material containing Mg, Li, and Ca, resulting in excellent brazing properties. Conversely, Mg, Li, and Ca contents in the brazing material that are lower than the range described above reduce the effect of oxide film breakup on the brazing sheet or mating material containing Mg, Li, and Ca. If the Mg, Li, and Ca contents exceed the range described above, oxidation of Mg, Li, and Ca proceeds during brazing heating, and an oxide with a volume change ratio greater than 0.990 is formed.

[0049] The brazing alloy may contain bi. In the aluminum alloy forming the brazing alloy, bi has the effect of reducing the surface tension of the molten Al-Si brazing alloy filler metal. If the brazing alloy contains bi, the bi content in the brazing alloy is 1.00 wt% or less, preferably 0.50 wt% or less, more preferably 0.05 to 0.40 wt%, and most preferably 0.10 to 0.30 wt%. The bi content in the brazing alloy, falling within the range described above, allows the surface tension reduction effect to be readily achieved. On the other hand, if the bi content in the brazing alloy exceeds the range described above, the surface of the brazing alloy becomes blackened after brazing, and its brazing properties are reduced.

[0050] The brazing alloy may contain one, two, or more of Na, Sr, and Sb. In the aluminum alloy forming the brazing alloy, the Na, Sr, and Sb micronize the Si particles in the brazing alloy, thereby improving the flowability of the brazing alloy filler metal. If the brazing alloy contains Na, the Na content in the brazing alloy is 0.05 wt% or less, preferably 0.005 to 0.04 wt%, and particularly preferably 0.007 to 0.04 wt%. If the brazing alloy contains Sr, the Sr content in the brazing alloy is 0.05 wt% or less, preferably 0.005 to 0.04 wt%, and particularly preferably 0.005 to 0.02 wt%. If the brazing material contains Sb, the Sb content in the brazing material is 0.05 wt% or less, and preferably 0.005 to 0.04 wt%.

[0051] The brazing alloy may contain one or two elements of zinc and copper. In the aluminum alloy forming the brazing alloy, the zinc and copper reduce the melting point of the brazing alloy, enabling brazing at a temperature below 600°C, which is considered a common brazing temperature. If the brazing alloy contains zinc, the zinc content is preferably 8.00% by mass or less, more preferably 1.00 to 8.00% by mass, more preferably 2.00 to 8.00% by mass, and more preferably 3.00 to 5.00% by mass, from the perspective of easily achieving the effect of reducing the melting point of the brazing alloy. On the other hand, if the zinc content in the brazing alloy exceeds 8.00% by mass, cracks will occur in the brazing alloy during cold rolling, and an intact sheet material will not be obtained.Furthermore, if the brazing alloy contains zinc (Zn), the Zn content in the brazing alloy is preferably 3.00 wt% or less, from the perspective of easily achieving the effect of preventing the core material from corroding by making the brazing alloy less noble and allowing it to corrode before the core material. If the brazing alloy contains copper (Cu), the Cu content in the brazing alloy is 4.00 wt% or less, preferably 0.50 to 4.00 wt%, and particularly preferably 1.00 to 2.50 wt%. A Cu content in the brazing alloy within the range described above improves the effect of reducing the melting point of the brazing alloy. On the other hand, if the Cu content in the brazing alloy exceeds the range described above, cracks will occur in the brazing alloy during cold rolling, and an intact sheet material will not be obtained.

[0052] The brazing alloy may contain iron (Fe). In the aluminum alloy forming the brazing alloy, relatively coarse-grained Fe-Al-Fe compounds crystallize, thus promoting grain micronization of the brazing alloy after brazing. If the brazing alloy contains Fe, the Fe content is 1.00 wt% or less, preferably 0.10 to 0.50 wt%, and particularly preferably 0.20 to 0.50 wt%. With an Fe content in the brazing alloy within the range described above, the grain micronization effect is readily achieved. On the other hand, if the Fe content in the brazing alloy exceeds the range described above, large intermetallic compounds readily form during casting, and machinability is reduced.

[0053] The brazing alloy can contain one, two, or more of Mn, Cr, Ti, and Zr. In the aluminum alloy forming the brazing alloy, Mn, Cr, Ti, and Zr precipitate relatively coarse Al-Mn-based, Al-Cr-based, Al-Ti-based, and Al-Zr-based compounds, respectively, thus contributing to grain coarsening after brazing. If the brazing alloy contains Mn, the Mn content is 1.00 wt% or less, and preferably 0.10 to 0.60 wt%. With a Mn content in the brazing alloy within the range described above, the grain coarsening effect is readily achieved. On the other hand, if the Mn content in the brazing alloy exceeds the range described above, large intermetallic compounds readily form during casting, and machinability is reduced. If the brazing alloy contains Cr, the Cr content in the brazing alloy is 0.30 wt% or less, and preferably 0.01 to 0.03 wt%.With a Cr content in the brazing alloy that falls within the range described above, the grain coarsening effect is easily achieved. On the other hand, if the Cr content in the brazing alloy exceeds the range described above, large intermetallic compounds are easily formed during casting, and machinability is reduced. If the brazing alloy contains Ti, the Ti content in the brazing alloy is 0.30 wt% or less, preferably 0.10 wt% or less, and particularly preferably 0.01 to 0.03 wt%. With a Ti content in the brazing alloy that falls within the range described above, the grain coarsening effect is easily achieved. On the other hand, if the Ti content in the brazing alloy exceeds the range described above, large intermetallic compounds are easily formed during casting, and machinability is reduced.If the brazing alloy contains Zr, the Zr content in the brazing alloy is 0.30 wt% or less, and preferably 0.01 to 0.03 wt%. With a Zr content in the brazing alloy that falls within the range described above, the grain coarsening effect is readily achieved. On the other hand, if the Zr content in the brazing alloy exceeds the range described above, large intermetallic compounds are easily formed during casting, and machinability is reduced. The grain size after brazing is adjusted using the processes described above. The effect of the present invention can be sufficiently achieved within the range described above.

[0054] The brazing alloy may contain In. In the aluminum alloy forming the brazing alloy, In has the effect of preventing corrosion of the core material by setting the potential of the brazing alloy as less noble and allowing corrosion of the brazing alloy to take precedence over the core material. If the brazing alloy contains In, the In content in the brazing alloy is 0.10 wt% or less, preferably 0.01 to 0.03 wt%, and particularly preferably 0.02 to 0.03 wt%. With the In content in the brazing alloy falling within the range described above, the potential matching effect is readily achieved. On the other hand, if the In content in the brazing alloy exceeds the range described above, the natural electrode potential becomes too low, and the corrosion resistance is reduced.

[0055] The brazing alloy may contain tin (Sn). In the aluminum alloy forming the brazing alloy, the tin has the effect of preventing corrosion of the core material by setting the potential of the brazing alloy as less noble and allowing corrosion of the brazing alloy to take precedence over the core material. If the brazing alloy contains tin, the tin content in the brazing alloy is 0.10 wt% or less, and preferably 0.01 to 0.05 wt%. With the tin content in the brazing alloy falling within the range described above, the potential matching effect is readily achieved. On the other hand, if the tin content in the brazing alloy exceeds the range described above, the natural electrode potential becomes too low, and the corrosion resistance is reduced.

[0056] The brazing alloy may contain Ag, B, Be, Cd, Co, Ga, Ge, Mo, Ni, P, Pb, V, Hg and Y of 0.05 wt% or less as unavoidable impurities.

[0057] The cladding material of the aluminum alloy brazing sheet according to the present invention is made of aluminum or an aluminum alloy cladding material having a zinc content of 6.00% by mass or less, the remainder being aluminum and unavoidable impurities. In the aluminum alloy brazing sheet according to the present invention, the corrosion resistance of the aluminum product after brazing is further improved by the sacrificial anti-corrosion effect, since the cladding material is applied.In the aluminum alloy brazing sheet according to the present invention, an oxide is formed on a surface on the brazing material side during brazing heating. This oxide comprises one or two or more of Mg, Li, and Ca and has a volume change ratio of 0.990 or less, preferably 0.700 to 0.970, more preferably 0.700 to 0.950, and particularly preferably 0.800 to 0.900, compared to a surface oxide film formed before brazing heating. With this structure, a new surface of the brazing material is exposed during brazing heating in an inert gas atmosphere without the use of a flux, and the aluminum alloy brazing sheet exhibits excellent brazing properties.For this reason, the aluminium alloy brazing sheet according to the present invention produces the effect of the present invention described above, regardless of whether the plating material is plated or unplated onto a surface of the core material opposite a surface provided with the brazing material.

[0058] If the plating material is made of aluminium, the purity of the aluminium is not particularly limited, but preferably 99.0 wt% or more, and particularly preferably 99.5 wt% or more.

[0059] If the cladding material is an aluminum alloy containing zinc, the zinc content in the cladding material is 6.00 wt% or less, and preferably 3.00 wt% or less. With a zinc content in the cladding material within the range described above, the sacrificial anti-corrosion effect is enhanced. Conversely, if the zinc content in the cladding material exceeds the range described above, the potential of the cladding material decreases excessively, and corrosion progression may be accelerated.

[0060] The cladding material may contain manganese (Mn). In the aluminum alloy forming the cladding material, Mn contributes to improved strength. If the cladding material contains Mn, the Mn content is 2.00 wt% or less, and preferably 0.30 to 1.80 wt%. With a Mn content in the cladding material within the range described above, the strength improvement is readily achieved. Conversely, if the Mn content in the cladding material exceeds the range described above, cracking is likely to occur during rolling of the material.

[0061] The cladding material may contain magnesium. In the aluminum alloy forming the cladding material, magnesium contributes to improved strength. If the cladding material contains magnesium, the magnesium content is 3.00 wt% or less, preferably 0.30 to 1.80 wt%, and particularly preferably 0.40 to 1.80 wt%. With a magnesium content in the cladding material within the range described above, the strength-enhancing effect is readily achieved. On the other hand, if the magnesium content in the cladding material exceeds the range described above, cracking is likely to occur during rolling of the material.

[0062] The cladding material may contain silicon (Si). In the aluminum alloy forming the cladding material, Si contributes to improved strength. If the cladding material contains Si, the Si content in the cladding material is 5.00 wt% or less, preferably 0.10 to 1.50 wt%, more preferably 0.10 to 1.00 wt%, and particularly preferably 0.20 to 1.00 wt%. With a Si content in the cladding material that falls within the range described above, the strength of the cladding material increases. Furthermore, the Si content in the cladding material is 1.50 to 5.00 wt%, and particularly preferably 2.50 to 4.50 wt%.When the silicon content falls into the range of 1.50 to 5.00 wt%, the cladding material changes to a semi-molten state during brazing, thus introducing a very small amount of liquid-phase brazing alloy filler metal and improving brazing properties when the cladding material surface serves as the brazing surface. If the silicon content in the cladding material exceeds the range described above, the melting point becomes too low, melting occurs during brazing, and the cladding material deforms.

[0063] The cladding material may contain iron (Fe). In the aluminum alloy forming the cladding material, Fe contributes to improved strength. If the cladding material contains Fe, the Fe content in the cladding material is 1.50 wt% or less, preferably 0.10 to 0.70 wt%, and particularly preferably 0.10 to 0.50 wt%. With an Fe content in the cladding material within the range described above, the strength improvement is readily achieved. On the other hand, if the Fe content in the cladding material exceeds the range described above, corrosion resistance decreases, and large-scale corrosion is easily formed.

[0064] The cladding material may contain copper. In the aluminum alloy forming the cladding material, copper contributes to improved strength. If the cladding material contains copper, the copper content is 1.00 wt% or less, and preferably 0.10 to 1.00 wt%. With a copper content in the cladding material within the range described above, the strength improvement is readily achieved. Conversely, if the copper content in the cladding material exceeds the range described above, boundary corrosion is more likely to occur.

[0065] The cladding material may contain one, two, or more of Ti, Zr, and Cr. In the aluminum alloy forming the cladding material, Ti, Zr, and Cr exhibit a strength-enhancing effect through solution hardening. If the cladding material contains Ti, the Ti content in the cladding material is 0.30 wt% or less, and preferably 0.10 to 0.20 wt%. If the cladding material contains Zr, the Zr content in the cladding material is 0.30 wt% or less, and preferably 0.10 to 0.20 wt%. If the cladding material contains Cr, the Cr content in the cladding material is 0.30 wt% or less, and preferably 0.10 to 0.20 wt%. With a Ti, Zr or Cr content in the plating material that falls within the range described above, the strength improvement effect is easily achieved.On the other hand, if the Ti, Zr or Cr content in the plating material exceeds the range described above, huge intermetallic compounds are easily formed during casting, and plastic machinability is reduced.

[0066] The cladding material may contain inhalant (In). In the aluminum alloy forming the cladding material, In has the effect of preventing corrosion of the core material by setting the potential of the cladding material as less noble and allowing corrosion of the cladding material to occur prioritized over that of the core material. If the cladding material contains In, the In content in the cladding material is 0.10 wt% or less, and preferably 0.01 to 0.03 wt%. With the In content in the cladding material falling within the described range, the potential matching effect is readily achieved. On the other hand, if the In content in the cladding material exceeds the range described above, the natural electrode potential becomes too low, and the corrosion resistance is reduced.

[0067] The cladding material may contain tin (Sn). In the aluminum alloy forming the cladding material, the Sn has the effect of preventing corrosion of the core material by setting the potential of the cladding material as less noble, thus allowing corrosion of the cladding material to take precedence over the core material. If the cladding material contains Sn, the Sn content in the cladding material is 0.10 wt% or less, and preferably 0.01 to 0.05 wt%. With an Sn content in the cladding material within the range described above, the potential matching effect is readily achieved. On the other hand, if the Sn content in the cladding material exceeds the range described above, the natural electrode potential becomes too low, and the corrosion resistance is reduced.

[0068] The plating material may contain Ag, B, Be, Bi, Ca, Cd, Co, Ga, Ge, Li, Mo, Na, Ni, P, Pb, Sr, V and Hg of 0.05 wt% or less as unavoidable impurities.

[0069] The aluminum alloy brazing sheet according to the present invention is an aluminum alloy brazing sheet in which an oxide is formed on a surface thereof by brazing heating in an inert gas atmosphere without the use of a flux, and the oxide comprises one or two or more of Mg, Ni and Ca and has a volume change ratio of 0.990 or less, preferably 0.700 to 0.970, more preferably 0.700 to 0.950, and particularly preferably 0.800 to 0.900, to a surface oxide film formed before brazing heating.When brazing in an inert gas atmosphere without the use of a flux, if the oxide containing Mg, Li and Ca has undergone brazing and exhibits a volume change ratio that falls within the range described above, compared to a surface oxide formed before brazing, and if the formed particulate oxide contains Mg, Li and Ca, since a new surface of the brazing material is effectively exposed during brazing, the aluminum alloy brazing sheet exhibits excellent brazing properties.

[0070] In contrast, when brazing in an inert gas atmosphere without the use of a flux, if the oxide containing one or two or more of Mg, Li and Ca, and which has been subjected to brazing, exhibits a volume change ratio exceeding the range described above, to a surface oxide formed before brazing, a new surface of the brazing material is not readily exposed upon brazing.In the present invention, the volume change ratio of the oxide comprising one or two or more Mg, Li, and Ca formed by brazing is a volume change ratio to an oxide film formed on the surface of the brazing material prior to brazing, and a value calculated using the expression "volume per oxygen atom of oxide particles comprising one or two or more Mg, Li, and Ca formed by brazing / volume per oxygen atom of an oxide film formed on the surface of the brazing material prior to brazing". In this expression, the volume per oxygen atom is calculated by dividing the molecular weight of the oxide by the density of the oxide.

[0071] Mg, Li, and Ca have a lower free energy of oxide formation than that of Al and are capable not only of reducing the oxide film but also of forming an oxide with a volume change ratio of 0.990 or less. For this reason, Mg, Li, and Ca are effective constituents for exposing a new surface of the brazing material upon brazing heating. For example, although the volume change ratio of MgO is 0.994, the volume change ratio of MgAl₂O₄ is 0.863 and less than 0.990. In contrast, Ba, Th, Nd, and the like are elements that have a lower free energy of oxide formation than that of Al but are not effective constituents because they do not form an oxide with a volume change ratio of 0.990 or less. For example, the volume change ratios of BaO and BaAl₂O₄, which act as oxides containing Ba, are 2.366 and 0.863, respectively.1.377, and Ba does not contain any oxide that has a volume change ratio of 0.990 or less.

[0072] An oxide film is formed on the surface of the brazing material of the aluminum alloy brazing sheet according to the present invention. Furthermore, the molar ratio of each of Mg, Li, and Ca to Al in the oxide film formed on the surface of the brazing material of the aluminum alloy brazing sheet according to the present invention is 0.50 or less in terms of atoms. With this molar ratio (such as Mg / Al) of each of Mg, Li, and Ca to Al in the oxide film formed on the surface of the brazing material falling within the range described above in terms of atoms, the volume change ratio of the oxide containing Mg, Li, and Ca, determined by brazing heat on the oxide film formed on the surface of the brazing material prior to brazing, is set to 0.990 or less.If the oxide film formed on the surface of the brazing material of the aluminium alloy brazing sheet according to the present invention comprises two or more elements of Mg, Li and Ca, the fact that the molar ratio of each of Mg, Li and Ca to Al is 0.50 or less in terms of atoms means that for each of Mg, Li and Ca the molar ratio of each of Mg, Li and Ca to Al is 0.5 or less in terms of atoms.

[0073] The thickness of the oxide film formed on the surface of the brazing material of the aluminum alloy brazing sheet according to the present invention is preferably 50 nm or less, and more preferably 10 nm or less, with regard to the ease of oxide film breakup. If the thickness of the oxide film formed on the surface of the brazing material exceeds 50 nm, it becomes difficult for oxide film breakup to progress.

[0074] The aluminum alloy brazing sheet according to the present invention is suitably produced by a method for producing the aluminum alloy brazing sheet according to the present invention, which is described below.

[0075] A method for producing an aluminum alloy brazing sheet according to the present invention is a method for producing an aluminum alloy brazing sheet, comprising performing at least hot working and cold working for (1) a stacked structure obtained by stacking a brazing material ingot and a core material ingot in that order; (2) a stacked structure obtained by stacking a brazing material ingot, a core material ingot and a brazing material ingot in that order;or (3) a stacked structure obtained by stacking a brazing ingot, a core ingot and a cladding ingot in that order, to obtain an aluminium alloy brazing sheet, wherein the core ingot is formed of aluminium or an aluminium alloy comprising one or two or more of Fe of 1.50 wt% or less, Si of 1.50 wt% or less, Cu of 2.00 wt% or less, Mn of 2.00 wt% or less, Zn of 3.00 wt% or less, Cr of 0.30 wt% or less, Ti of 0.30 wt% or less, Zr of 0.30 wt% or less, In of 0.10 wt% or less and Sn of 0.10 wt% or less, the remainder being aluminium and unavoidable impurities; the brazing ingot is formed from an aluminum alloy having Si of 4.00 to 13.00 wt% and one or two or more of Mg of more than 0.03 wt% and 3.00 wt% or less, Li of more than 0.03 wt% and 3.00 wt% or less and Ca of more than 0.03 wt% and 3.00 wt% or less, the remainder being aluminum and unavoidable impurities, the plating material ingot is formed from aluminium or an aluminium alloy having a Zn content of 6.00 wt% or less, the remainder being aluminium and unavoidable impurities, and an intermediate annealing treatment, a final annealing treatment or an annealing treatment is carried out, wherein the intermediate annealing treatment is carried out between rolling passes during cold working to heat the stacked structure at 250 to 450°C for one hour or more in an atmosphere controlled to have an oxygen concentration of 10,000 ppm or less and a dew point of 20°C or less, and the final annealing treatment is carried out after a final pass of cold working to heat the stacked structure at 250 to 450°C for one hour or more in an atmosphere controlled to have an oxygen concentration of 10.The annealing treatment is carried out both between rolling passes during cold working and after the last pass of cold working to heat the stacked structure at 250 to 450°C for one hour or more in an atmosphere regulated to have an oxygen concentration of 10,000 ppm or less and a dew point of 20°C or less.

[0076] A method for producing an aluminum alloy brazing sheet according to the present invention is a method for producing an aluminum alloy brazing sheet, comprising at least hot working and cold working for: (1) a stacked structure obtained by stacking a brazing material ingot and a core material ingot; (2) a stacked structure obtained by stacking a brazing material ingot on each of the two side surfaces of the core material ingot; or a stacked structure obtained by stacking a brazing material ingot on one side surface of a core material ingot and stacking a cladding material ingot on the other side surface of the core material ingot, i.e.(1) a stacked structure obtained by stacking a brazing ingot and a core material ingot in that order; (2) a stacked structure obtained by stacking a brazing ingot, a core material ingot and a brazing ingot in that order; or (3) a stacked structure obtained by stacking a brazing ingot, a core material ingot and a cladding material in that order, for obtaining an aluminium alloy brazing sheet.

[0077] In the method for producing an aluminium alloy brazing sheet according to the present invention, the types and contents of the additive compositions in the core material ingot, the brazing material ingot and the cladding material ingot are the same as the compositions and contents of those in the core material, the brazing material and the cladding material of the aluminium alloy brazing sheet according to the present invention.

[0078] In particular, the core material ingot is made of aluminum or an aluminum alloy containing one or two or more of the following elements: Fe of 1.50 wt% or less, preferably 0.10 to 0.70 wt%, and particularly preferably 0.20 to 0.60 wt%; Si of 1.50 wt% or less, preferably 0.10 to 1.00 wt%, and particularly preferably 0.30 to 0.75 wt%; Cu of 2.00 wt% or less, preferably 0.10 to 1.00 wt%, and particularly preferably 0.15 to 0.80 wt%; Mn of 2.00 wt% or less, preferably 0.30 to 1.80 wt%, and particularly preferably 0.30 to 1.50 wt%; Zn of 3.00 wt% or less, preferably 0.50 to 3.00 wt%, and particularly preferably 1.50 to 3.00 wt%; Cr of 0.30 wt% or less, and preferably 0.10 to 0.20 wt%, Ti of 0.30 wt% or less, preferably 0.10 to 0.20 wt%, and particularly preferably 0.12 to 0.18 wt%, Zr of 0.30 wt% or less, and preferably 0.10 to 0.20 wt%, In of 0.10 wt% or less, and preferably 0.01 to 0.03 wt%,and Sn of 0.10 wt% or less, and preferably 0.01 to 0.10 wt%, and, if necessary, Bi of 1.00 wt% or less, and preferably 0.10 to 1.00 wt%, and, if necessary, one or two or more Mg of 3.00 wt% or less, and preferably 0.10 to 1.80 wt%, Fe of 3.00 wt% or less, and preferably 0.10 to 1.80 wt%, and Ca of 3.00 wt% or less, and preferably 0.10 to 1.80 wt%, the remainder being aluminum and unavoidable impurities. The core material ingot may contain Ag, B, Be, Cd, Co, Ga, Ge, Mo, Na, Ni, P, Pb, Sr, V, Hg, and Y of 0.05 wt% or less as unavoidable impurities.

[0079] The brazing ingot is made of an aluminum alloy comprising Si of 4.00 to 13.00%, and preferably 4.50 to 12.00% by mass, and one or two or more of Mg of more than 0.03% by mass and 3.00% by mass or less, preferably 0.10 to 1.80% by mass, and particularly preferably 0.60 to 1.20% by mass, Li of more than 0.03% by mass and 3.00% by mass or less, preferably 0.04 to 1.80% by mass, and particularly preferably 0.10 to 1.80% by mass, and Ca of more than 0.03% by mass and 3.00% by mass or less, preferably 0.05 to 1.80% by mass, and particularly preferably 0.10 to 1.80% by mass, and, if necessary, Bi of 1.00% by mass or less, preferably 0.50% by mass or less. preferably 0.05 to 0.40 wt%, and particularly preferably 0.10 to 0.30 wt%, and, if necessary, one or two or more of Na of 0.05 wt% or less, preferably 0.005 to 0.04 wt%, and particularly preferably 0.007 to 0.04 wt%, Sr of 0.05 wt% or less, preferably 0.005 to 0.04 wt%,and particularly preferably 0.005 to 0.02 wt%, Sb of 0.05 wt% or less, and preferably 0.005 to 0.04 wt%, Zn of 8.00 wt% or less, preferably 1.00 to 8.00 wt%, more preferably 2.00 to 8.00 wt%, and particularly preferably 3.00 to 5.00 wt%, Cu of 4.00 wt% or less, preferably 0.50 to 4.00 wt%, and particularly preferably 1.00 to 2.50 wt%, Fe of 1.00 wt% or less, preferably 0.10 to 0.50 wt%, and particularly preferably 0.20 to 0.50 wt%, Mn of 1.00 wt% or less, and preferably 0.10 to 0.60 wt%, Cr of 0.30 wt% or less, and preferably 0.01 to 0.03 wt%, Ti of 0.30 wt% or less, preferably 0.10 wt% or less, and particularly preferably 0.01 to 0.03 wt%, Zr of 0.30 wt% or less, and preferably 0.01 to 0.03 wt%, In of 0.10 wt% or less, preferably 0.01 to 0.03 wt%, and particularly preferably 0.02 to 0.03 wt%, and Sn of 0.10 wt% or less, and preferably 0.01 to 0.05 wt%,the remainder being aluminum and unavoidable impurities. The brazing ingot may contain one or two or more of Ag, B, Be, Cd, Co, Ga, Ge, Mo, Ni, P, Pb, V, Hg and Y at 0.05 wt% or less as unavoidable impurities.

[0080] The plating material ingot is made of aluminum or an aluminum alloy having a zinc content of 6.00 wt% or less, and preferably 3.00 wt% or less, and, if necessary, one or two or more of manganese of 2.00 wt% or less, and preferably 0.30 to 1.80 wt%, magnesium of 3.00 wt% or less, preferably 0.30 to 1.80 wt%, and particularly preferably 0.40 to 1.80 wt%, silicon of 5.00 wt% or less, preferably 0.10 to 1.50 wt%, preferably 0.10 to 1.00 wt%, and particularly preferably 0.20 to 1.00 wt%, or silicon of 5.00 wt% or less, preferably 2.50 to 4.50 wt%, iron of 1.50 wt% or less, preferably 0.10 to 0.70 wt%, and particularly preferably 0.10 to 0.50 wt%, Cu of 1.00 wt% or less, and preferably 0.10 to 1.00 wt%, Ti of 0.30 wt% or less, and preferably 0.10 to 0.20 wt%, Zr of 0.30 wt% or less, and preferably 0.10 to 0.20 wt%, Cr of 0.30 wt% or less, and preferably 0.10 to 0.20 wt%,The cladding material ingot may contain Ag, B, Be, Bi, Ca, Cd, Co, Ga, Ge, Li, Mo, Na, Ni, P, Pb, Sr, V, Hg, and Y in amounts of 0.05% by mass or less, preferably 0.01 to 0.03% by mass, and Sn in amounts of 0.10% by mass or less, preferably 0.01 to 0.05% by mass, the remainder being aluminum and unavoidable impurities.

[0081] In the method for producing an aluminum alloy brazing alloy sheet according to the present invention, hot rolling and cold rolling are performed to produce (1) a stacked structure obtained by stacking a brazing alloy ingot and a core material ingot in that order; (2) a stacked structure obtained by stacking a brazing alloy ingot, a core material ingot, and a brazing alloy ingot in that order; or (3) a stacked structure obtained by stacking a brazing alloy ingot, a core material ingot, and a cladding material in that order. In hot rolling, a clad sheet is formed at 400 to 550°C and then machined to a thickness of 2 to 3 mm while being held in a hot state.In cold rolling, a clad sheet is rolled in a cold manner with a plurality of passes and processed to have a predetermined thickness of an aluminum alloy brazing alloy sheet.

[0082] In the method for producing an aluminum alloy brazing sheet according to the present invention, an intermediate annealing treatment, a final annealing treatment, or a final annealing treatment is performed. The intermediate annealing treatment is performed between rolling passes during cold working to heat the stacked structure at 250 to 450°C for one hour or more in an atmosphere controlled to have an oxygen concentration of 10,000 ppm or less and a dew point of 20°C or less. The final annealing treatment is performed after the last cold working pass to heat the stacked structure at 250 to 450°C for one hour or more in an atmosphere controlled to have an oxygen concentration of 10,000 ppm or less and a dew point of 20°C or less.The intermediate or final annealing treatment is performed both between cold-working passes and after the final cold-working pass to heat the stacked structure at 250 to 450°C for one hour or more in an atmosphere controlled to maintain an oxygen concentration of 10,000 ppm or less and a dew point of 20°C or less. The intermediate or final annealing treatment has a significant impact on the oxide film condition due to its high-temperature nature. The atmosphere used for the intermediate or final annealing treatment is an inert gas atmosphere, such as nitrogen, argon, or carbon dioxide. By performing an intermediate or final annealing treatment in an atmosphere controlled to maintain an oxygen concentration of 10,000 ppm or less and a dew point of 20°C or less, the oxide film is significantly improved.If the atmospheric oxygen concentration is 000 ppm or less and the dew point is 20°C or less, an aluminum alloy brazing sheet is readily obtained in which oxide particles containing Mg, Li, and Ca, exhibiting a volume change ratio of 0.990 or less, are formed on the surface of the sheet by brazing. If the atmospheric oxygen concentration exceeds 10,000 ppm during intermediate or final annealing, oxide film growth is promoted, and / or the concentration of Mg, Li, and Ca in the oxide film increases slightly. If the atmospheric dew point exceeds 20°C during intermediate or final annealing, a hydroxide film is readily formed, and the oxide film thickens slightly.

[0083] In the method for producing an aluminum alloy brazing sheet according to the present invention, the brazing material surface of the brazing sheet can, if necessary, be etched using an aqueous acid solution and / or an aqueous basic solution after an intermediate annealing or a final annealing treatment. Performing etching makes the oxide film formed by heating during the intermediate or final annealing treatment brittle or removes it. As a result, the brazing properties of the brazing sheet can be further improved. In the case of etching the brazing material surface, when the brazing material is plated onto a side surface of the core material, it may be possible to etch only the brazing material surface, or both the brazing material surface and the opposing surface may be etched.When the brazing alloy material is plated onto both sides of the core material, both sides are etched.

[0084] Examples of acid solutions used for etching the brazing alloy include aqueous solutions such as sulfuric acid, hydrochloric acid, nitric acid, phosphoric acid, and hydrofluoric acid. One of these acids may be used, or two or more may be used together. For more efficient oxide film removal, it is preferred to use a mixed aqueous solution containing hydrofluoric acid and an acid other than hydrofluoric acid, and more preferably a mixed aqueous solution of hydrofluoric acid and sulfuric acid, or a mixed aqueous solution of hydrofluoric acid and nitric acid. Examples of basic solutions used for etching the brazing alloy include aqueous solutions such as sodium hydroxide, potassium hydroxide, and calcium hydroxide. One of these basic solutions may be used, or two or more may be used together.In the case of etching using a basic solution, cleaning using an aqueous sulfuric acid solution and / or a nitric acid solution is preferably carried out after etching.

[0085] In the method for producing an aluminum alloy brazing sheet according to the present invention, it is preferred to suppress the growth of an oxide film and the concentration of Mg, Li and Ca in the oxide film during the manufacturing process.

[0086] The aluminum alloy brazing sheet according to the present invention is used for brazing in an inert gas atmosphere without the use of a flux. Furthermore, the aluminum alloy brazing sheet according to the present invention is subjected to brazing heating in an inert gas atmosphere without the use of a flux. In this way, since oxide particles containing Mg, Li, and Ca, which have a volume change ratio of 0.990 or less compared to the oxide film formed before brazing heating, are formed on the surface of the aluminum alloy brazing sheet, a new surface of the brazing material is readily exposed, and excellent brazing properties are exhibited.

[0087] An aluminum alloy sheet (A) according to the present invention is an aluminum alloy sheet obtained by subjecting the aluminum alloy brazing sheet according to the present invention to brazing in an inert gas atmosphere without using a flux, wherein oxide particles comprising Mg, Li and Ca and having a volume change ratio of 0.990 or less to the oxide of the aluminum alloy brazing sheet that has not been subjected to brazing are formed on the surface of the aluminum alloy sheet.Since the oxide of Mg, Li, and Ca formed on the surface of the aluminum alloy sheet (A) according to the present invention is particulate and has a volume change ratio of 0.990 or less compared to the oxide of the aluminum alloy brazing sheet that has not been subjected to brazing, a new aluminum alloy surface appears on a portion of the brazing sheet's surface upon brazing. Examples of inert gases include nitrogen gas and argon gas. As the temperature increases, the oxygen concentration in the furnace is 100 ppm or less when the brazing sheet temperature is 400°C or higher, and 20 ppm or less, preferably 10 ppm or less, when the brazing sheet temperature is 570°C or higher.

[0088] The aluminium alloy sheet (A) according to the present invention is an aluminium alloy sheet obtained after the aluminium alloy brazing sheet has been brazed. EXAMPLES

[0089] The following is an explanation of examples of the present invention in comparison to comparative examples to demonstrate an effect of the present invention. The examples represent embodiments of the present invention, and the present invention is not limited to them.

[0090] Core material ingots and brazing material ingots with compositions listed in Table 1 and Table 2 were cast by continuous casting. Each of the procured core material ingots was surface-machined to a size of 163 mm × 163 mm. Subsequently, each of the core material ingots to be clad with brazing material on only one side surface was surface-machined to a size with a thickness of 27 mm, and each of the core material ingots to be clad with brazing material on both sides was surface-machined to a size with a thickness of 24 mm. Each of the procured brazing material ingots was hot-rolled to a thickness of 3 mm at 500°C and cut into sizes of 163 mm × 163 mm after cooling. [Table 1] [Table 2] Material number Alloy composition (mass%) Si Mg Li Approx Bi Sr Zn Cu Fe Mn Cr Ti Zr In Ba N / a Al F1 16,00 0,60 - - - - - - 0,20 - - - - - - - rest F2 10,00 - - 0,05 - - - - 0,20 - - - - - - - rest F3 12,00 1,00 - - 0,30 - - - 0,20 - - - - - - 0,007 rest F4 10,00 0,10 - - 0,15 0,02 - - 0,20 - - - - - - - rest F5 10,00 0,60 - - 0,15 0,02 1,00 - 0,20 - - 0,10 - - - - rest F6 12,00 0,60 - - 0,05 - - - 0,20 - - - - - - - rest F7 12,00 0,60 - - 0,30 - - - 0,20 - - - - - - - rest F8 4,50 0,60 - - 0,10 - 4,00 - 0,20 - - - - - - - rest F9 7,00 0,60 - - 0,10 - 4,00 - 0,20 - - - - - - - rest F10 12,00 0,10 - - 0,05 - - - 0,20 - - - - - - - rest F11 10,00 0,60 - - 0,30 - - - 0,20 - - 0,10 - - - - rest F12 12,00 0,60 - - 0,30 - 2,00 - 0,20 - - - - - - - rest F13 12,00 1,20 - - 0,30 - - - 0,20 - - - - - - - rest F14 12,00 2,92 - - 0,30 - - - 0,20 - - - - - - - rest F15 10,00 1,20 - - 0,10 - - - 0,20 - - - - 0,02 - - rest F16 12,00 0,60 - - 0,30 - - - 0,20 - - - - - - - rest F17 10,00 0,60 - - - - - - 0,20 - - - - - - - rest F18 10,00 3,00 - - - - - - 0,20 - - - - - - - rest F19 10,00 - - - - - - - 0,20 - - - - - - - rest F20 10,00 0,60 - - 0,50 - - - 0,20 - - - - - - - rest F21 10,00 0,60 - - 0,10 - - - 0,20 - - - - 0,03 - - rest F22 10,00 - 0,04 - 0,05 - - - 0,20 - - - - - - - rest F23 10,00 0,01 - - 0,02 - - - 0,20 - - - - - - - rest F24 10,00 1,50 - - 0,20 - - - 0,20 - - - - - - - rest F25 3,50 1,50 - - 0,20 - - - 0,20 - - - - - - - rest F26 10,00 3,50 - - 0,10 - - - 0,20 - - - - - - - rest

[0091] The prepared brazing bars and core bars were stacked in the combinations listed in Table 3. The combinations were then subjected to hot rolling and cold rolling, followed by a final annealing treatment under the conditions listed in Table 4 to produce annealed clad materials. Alternatively, the combinations were subjected to an intermediate annealing treatment under the conditions listed in Table 4 after hot rolling and cold rolling, followed by cold rolling to produce annealed clad materials.Other examples include the following combinations: intermediate annealing under the conditions listed in Table 4, followed by hot rolling and cold rolling, then cold rolling, and finally a final annealing treatment under the conditions listed in Table 4, to obtain annealed clad materials. Cleaning was performed after annealing in the cases listed in Table 4. The final thickness was set to 0.3 to 1.0 mm. The obtained clad sheet materials were used as test pieces.

[0092] The thickness of the oxide film on the brazing alloy surface of each test piece was measured by X-ray photoelectron spectroscopy (XPS). Oxygen was analyzed by XPS in the depth direction from the surface of the material, and the position of the measured full width at half maximum (FWHM) of oxygen was defined as the oxide film thickness. Additionally, a molar ratio (e.g., Mg / Al) of each of Mg, Li, and Ca to aluminum (total of metallic aluminum and aluminum compositions in the aluminum oxide) was calculated in terms of atoms within the oxide film thickness.

[0093] The oxide film thickness is expressed in the "Oxide Film Thickness" column of Table 4 as follows: a thickness of 10 nm or less (the most preferred thickness) is expressed as "A", a thickness greater than 10 nm and 50 nm or less as "B", and a thickness greater than 50 nm as "C". In the "Molar Ratio" column, a ratio of 0.1 or less is expressed as "A", a ratio greater than 0.1 and 0.5 or less as "B", and a ratio greater than 0.5 as "C".

[0094] The brazing properties of each test piece can be evaluated by performing a gap-filling test. Each test piece used in the gap-filling test was mounted with SUS fixtures in a state where a bare 3003 material was arranged as a vertical plate and the test piece as a horizontal plate, and brazed in a nitrogen atmosphere in a furnace without the use of a flux, in the same manner as in Fig.1. Under brazing conditions, the oxygen concentration in the furnace was controlled to 50 ppm or less when the test piece temperature was 400°C or higher during a temperature rise, and to 10 ppm or less when the test piece temperature was 570°C or higher. The maximum test piece temperature was set at 600°C. Although the length of the vertical plate of a standard gap-filling test (LWS T8801) is 55 mm, the length of the vertical plate of each of the test pieces was set to 25 mm, thus increasing the gradient of a gap formed between the horizontal and vertical plates. This implemented an evaluation procedure that simulates a heat exchanger with a large gap.

[0095] In the gap-filling test, brazability can be evaluated based on the length FL of a fillet formed after brazing. In the "Brazability" column of Table 3, the integrity of FL and the fillet is expressed using three levels: "A" indicates the case where the length FL was 5 mm or more and no partial fillet discontinuity occurred; "B" indicates the case where the length FL was 5 mm or more and a partial fillet discontinuity occurred; and "C" indicates the case where the length FL was less than 5 mm. Level "A" was determined to be a pass / fail level.

[0096] The volume change ratio of oxide particles containing Mg, Li, and Ca formed after brazing to an oxide film formed before brazing was determined by dividing the volume per oxygen atom by the molecular weight of the oxide by a density disclosed in the publicly available document and by the volume per oxygen atom of the oxide film formed before brazing. The film composition of the oxide film formed before brazing is Al₂O₃, and its density is given as 3.0 g / cm³. 3 “ determined. Table 3 lists an analysis of the procured clad sheet materials and performance test results of their brazability.

[0098] [Table 3] Nr. Brazing material 1 Core material Brazing material 2 Manufacturing conditions Atomic molar ratio to Al in oxide film Oxide film thickness (nm) Volume change ratio (type of oxide particles) Brazability element molar ratio Examples 1 F2 C1 - P5 Approx A A 0.967 (CaAl 12 Oh 19 ) A 2 F3 C2 - P1 Mg A A 0.863 (MgAl2O4) A 3 F4 C3 - P4 Mg A B 0.863 (MgAl2O4) A 4 F5 C3 - P4 Mg A B 0.863 (MgAl2O4) A 5 F6 C3 - P4 Mg A B 0.863 (MgAl2O4) A 6 F7 C3 - P6 Mg A A 0.863 (MgAl2O4) A 7 F8 C4 - P1 Mg A A 0.863 (MgAl2O4) A 8 F9 C4 - P1 Mg A A 0.863 (MgAl2O4) A 9 F11 C4 - P1 Mg B B 0.863 (MgAl2O4) A 10 F12 C6 - P1 Mg B B 0.863 (MgAl2O4) A 11 F13 C7 - P1 Mg B B 0.863 (MgAl2O4) A 12 F14 C7 - P1 Mg B B 0.863 (MgAl2O4) A 13 F17 C1 - P2 Mg A B 0.863 (MgAl2O4) A 14 F18 C1 - P3 Mg A B 0.863 (MgAl2O4) A 15 F20 C1 - P1 Mg B B 0.863 (MgAl2O4) A 16 F21 C9 - P1 Mg B B 0.863 (MgAl2O4) A 17 F22 C8 - P1 Li A A 0.822 (LiAl5O8) A 18 F24 C11 F24 P1 Mg A B 0.863 (MgAl2O4) A 19 F24 C13 - P6 Mg A A 0.863 (MgAl2O4) A Comparative examples 101 F25 C12 - P1 Mg A A 0.863 (MgAl2O4) C 102 F1 C1 Edge cracking occurred during hot rolling of brazing material and production was impossible. 103 F23 C10 P1 Mg A B 0.863 (MgAl2O4) C 104 F26 C12 - P1 Mg C C 0.994 (MgO) C

[0099] [Table 4] Condition number Annealing treatment condition Acid cleaning Oxygen concentration in atmosphere (ppm) Dew point in atmosphere (°C) P1 10,000 or less 20 or less Not executed P2 500 or less 0 or less Not executed P3 100 or less -10 or less Not executed P4 10,000 or less 10 or less After intermediate annealing P5 10,000 or less 10 or less After final annealing treatment P6 10,000 or less 10 or less After intermediate annealing and final annealing

Claims

[1] Aluminium alloy brazing sheet used for brazing in an inert gas atmosphere without the use of a flux, with: a brazing alloy material that is plated onto at least one side surface of a core material, where the core material is aluminum or an aluminum alloy core material containing one or two or more of Fe of 1.50 wt% or less, Si of 1.50 wt% or less, Cu of 2.00 wt% or less, Mn of 2.00 wt% or less, Zn of 3.00 wt% or less, Cr of 0.30 wt% or less, Ti of 0.30 wt% or less, Zr of 0.30 wt% or less, In of 0.10 wt% or less and Sn of 0.10 wt% or less, the remainder being aluminium and unavoidable impurities, is formed, wherein the brazing alloy material is an aluminum alloy brazing alloy material having Si of 4.00 to 13.00 wt% and one or two or more of Mg of more than 0.03 wt% and 3.00 wt% or less, Li of more than 0.03 wt% and 3.00 wt% or less, and Ca of more than 0.03 wt% and 3.00 wt% or less, the remainder being aluminum and unavoidable impurities, wherein an oxide is formed on a surface of the aluminium alloy brazing sheet by brazing heating, which has an oxide of one or two or more of Mg, Li and Ca and has a volume change ratio of 0.990 or less to a surface oxide film formed before brazing heating, and an atomic molar ratio of Mg, Ni and Ca to Al in the oxide formed on the surface of the aluminium alloy brazing sheet before brazing heating is 0.5 or less. [2] Aluminium alloy brazing sheet according to claim 1, wherein the aluminium alloy brazing sheet is a two-layer material in which the brazing material is plated onto a side surface of the core material. [3] Aluminium alloy brazing sheet according to claim 1, wherein the aluminium alloy brazing sheet is a three-layer material in which the brazing material is plated onto each of the two side surfaces of the core material. [4] Aluminium alloy brazing sheet according to claim 1, wherein the aluminum alloy brazing sheet is a three-layer material in which the brazing material is plated onto one side surface of the core material and a plating material is plated onto the other side surface of the core material, and the plating material is an aluminum alloy plating material formed from aluminum or an aluminum alloy having Zn of 6.00 wt% or less, the remainder being aluminum and unavoidable impurities. [5] Aluminium alloy brazing sheet according to any one of claims 1 to 4, wherein the core material further comprises one or two or more of Mg of 3.00 wt% or less, Li of 3.00 wt% or less and Ca of 3.00 wt% or less. [6] Aluminium alloy brazing sheet according to any one of claims 1 to 5, wherein the core material further comprises Bi of 1.00 wt% or less. [7] Aluminium alloy brazing sheet according to any one of claims 1 to 6, wherein the brazing material further comprises Bi of 1.00 wt% or less. [8] Aluminium alloy brazing sheet according to any one of claims 1 to 7, wherein the brazing material further comprises one or two or more of Na of 0.05 wt% or less, Sr of 0.05 wt% or less, Sb of 0.05 wt% or less, Zn of 8.00 wt% or less, Cu of 4.00 wt% or less, Fe of 1.00 wt% or less, Mn of 1.00 wt% or less, Cr of 0.30 wt% or less, Ti of 0.30 wt% or less, Zr of 0.30 wt% or less, In of 0.10 wt% or less and Sn of 0.10 wt% or less. [9] Aluminium alloy brazing sheet according to any one of claims 4 to 8, wherein the cladding material further comprises one or two or more of Mn of 2.00 wt% or less, Mg of 3.00 wt% or less, Si of 5.00 wt% or less, Fe of 1.50 wt% or less, Cu of 1.00 wt% or less, Ti of 0.30 wt% or less, Zr of 0.30 wt% or less, Cr of 0.30 wt% or less, In of 0.10 wt% or less and Sn of 0.10 wt% or less. [10] Aluminium alloy brazing sheet according to any one of claims 1 to 9, wherein the oxide formed on a brazing material surface of the aluminium alloy brazing sheet has a thickness of 50 nm or less. [11] A method for producing an aluminium alloy brazing sheet, comprising performing at least hot working and cold working for (1) a stacked structure obtained by stacking a brazing material ingot and a core material ingot in that order; (2) a stacked structure obtained by stacking a brazing material ingot, a core material ingot and a brazing material ingot in that order; or (3) a stacked structure obtained by stacking a brazing material ingot, a core material ingot and a cladding material in that order, for producing an aluminium alloy brazing sheet, wherein the core material ingot is formed from aluminium or an aluminium alloy comprising one or two or more of Fe of 1.50 wt% or less, Si of 1.50 wt% or less, Cu of 2.00 wt% or less, Mn of 2.00 wt% or less, Zn of 3.00 wt% or less, Cr of 0.30 wt% or less, Ti of 0.30 wt% or less, Zr of 0.30 wt% or less, In of 0.10 wt% or less and Sn of 0.10 wt% or less, the remainder being aluminium and unavoidable impurities, the brazing ingot is formed from an aluminum alloy having Si of 4.00 to 13.00 wt% and one or two or more of Mg of more than 0.03 wt% and 3.00 wt% or less, Li of more than 0.03 wt% and 3.00 wt% or less, and Ca of more than 0.03 wt% and 3.00 wt% or less, the remainder being aluminum and unavoidable impurities, the plating material ingot is formed from aluminium or an aluminium alloy having a Zn content of 6.00 wt% or less, the remainder being aluminium and unavoidable impurities, and an intermediate annealing treatment, a final annealing treatment, or an annealing treatment is carried out, wherein the intermediate annealing treatment is carried out between rolling passes during cold working to heat the stacked structure at 250 to 450°C for one hour or more in an atmosphere controlled to have an oxygen concentration of 10,000 ppm or less and a dew point of 20°C or less, and the final annealing treatment is carried out after a final pass of cold working to heat the stacked structure at 250 to 450°C for one hour or more in an atmosphere controlled to have an oxygen concentration of 10.The annealing treatment is carried out both between rolling passes during cold working and after the last pass of cold working to heat the stacked structure at 250 to 450°C for one hour or more in an atmosphere regulated to have an oxygen concentration of 10,000 ppm or less and a dew point of 20°C or less. [12] Method for producing an aluminium alloy brazing sheet according to claim 11, wherein the core material ingot further comprises one or two or more of Mg of 3.00 wt% or less, Li of 3.00 wt% or less and Ca of 3.00 wt% or less. [13] Method for producing an aluminium alloy brazing sheet according to claim 11 or 12, wherein one of the core material ingot and the brazing material ingot further comprises Bi of 1.0 wt% or less. [14] Method for producing an aluminium alloy brazing bar according to any one of claims 11 to 13, wherein the brazing bar further comprises one or two or more of Na of 0.05 wt% or less, Sr of 0.05 wt% or less, Sb of 0.05 wt% or less, Zn of 8.00 wt% or less, Cu of 4.00 wt% or less, Fe of 1.00 wt% or less, Mn of 1.00 wt% or less, Cr of 0.30 wt% or less, Ti of 0.30 wt% or less, Zr of 0.30 wt% or less, In of 0.10 wt% or less and Sn of 0.10 wt% or less. [15] Method for producing an aluminium alloy brazing sheet according to any one of claims 11 to 14, wherein the cladding material ingot further comprises one or two or more of Mn of 2.00 wt% or less, Mg of 3.00 wt% or less, Si of 5.00 wt% or less, Fe of 1.50 wt% or less, Cu of 1.00 wt% or less, Ti of 0.30 wt% or less, Zr of 0.30 wt% or less, Cr of 0.30 wt% or less, In of 0.10 wt% or less and Sn of 0.10 wt% or less. [16] A method for producing an aluminium alloy brazing sheet according to any one of claims 11 to 15, wherein a brazing material surface of a cladding material is subjected to etching using one or both of an aqueous acid solution and an aqueous basic solution, wherein the etching is carried out after the intermediate annealing treatment, if the intermediate annealing treatment is carried out, after the final annealing treatment, if the final annealing treatment is carried out, and at one or both of a time point after the intermediate annealing treatment and a time point after the final annealing treatment, if both the intermediate annealing treatment and the final annealing treatment are carried out.

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