Brazing sheet and manufacturing method thereof

Abstract

To provide a brazing sheet excellent in strength, corrosion resistance and brazing ability.SOLUTION: A brazing sheet 1 comprises a core material 11, an intermediate material 12 laminated on one surface of the core material 11, a brazing filler metal 13 laminated on the intermediate material 12, and a sacrificial anode material 14 laminated on the other surface of the core material 11. The core material 11 has a specific chemical composition, and a fibrous structure in a metallographic structure. The intermediate material 12 comprises aluminum alloy having a pitting-corrosion electric potential baser than that of the core material 11. The brazing filler metal 13 has a specific chemical composition, and a thickness of 18 μm or more. The sacrificial anode material 14 has a specific chemical composition, and a thickness of 20 μm or more. A total sum of the thicknesses of the core material 11, the intermediate material 12, the brazing filler metal 13 and the sacrificial anode material 14 is 120-350 μm. The thickness of the core material 11 is 55% or more relative to the total sum of the thicknesses of the core material 11, the intermediate material 12, the brazing filler metal 13 and the sacrificial anode material 14.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] Taking advantage of aluminum alloys' properties such as light weight for a metal and excellent thermal conductivity, they are used in automotive heat exchangers such as radiators, evaporators, heaters, condensers, etc. This type of heat exchanger has multiple tubes for circulating refrigerant and headers for distributing the refrigerant among the tubes and collecting the refrigerant that flows out of the tubes.

[0003] In addition to high thermal conductivity, tubes in heat exchangers are required to have various excellent properties, such as high durability against thermal fatigue and vibration during driving, corrosion resistance against external corrosion caused by water splashes from the road surface, and corrosion resistance against internal corrosion caused by the use of cooling water in which rust prevention functions are ineffective. To meet these requirements, heat exchanger tubes are sometimes composed of a brazing sheet including a core material, a brazing material laminated on one side of the core material, and a sacrificial anode material laminated on the other side of the core material.

[0004] In recent years, as part of efforts to reduce the weight of automobiles, there has been a demand for further reductions in the mass of heat exchangers. To meet this demand, there is a strong demand for further reductions in the thickness of the brazing sheets used in tubes while maintaining the excellent properties mentioned above.

[0005] As such a brazing sheet, for example, Patent Document 1 describes an aluminum alloy clad material in which one side of a core material is clad with a sacrificial anode material and the other side is clad with a brazing material via an intermediate material.

[0006] The core material in the clad material of Patent Document 1 is made of an aluminum alloy containing at least 0.8 to 1.8% (mass %, the same applies hereinafter) of Mn (manganese) and 0.1 to 1.0% of Mg (magnesium). The intermediate material is made of an aluminum alloy containing at least 0.8 to 1.8% of Mn. The sacrificial anode material is made of an aluminum alloy containing at least 0.8 to 1.8% of Mn and 0.5 to 10% of Zn (zinc). The brazing material is made of an aluminum alloy containing at least 6 to 13% of Si (silicon). [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-131923 Summary of the Invention [Problem to be solved by the invention]

[0008] In the clad material of Patent Document 1, a relatively large amount of Mn is added to the sacrificial anode material to improve its strength. However, as the Mn content in the sacrificial anode material increases, the amount of dissolved Mn in the sacrificial anode material tends to increase. Because the dissolved Mn in the sacrificial anode material has the effect of making the potential of the sacrificial anode material nobler, an increased amount of dissolved Mn in the sacrificial anode material may result in a decrease in corrosion resistance against internal corrosion.

[0009] Furthermore, if the Mn content in the sacrificial anode material is high, when the sacrificial anode material and the brazing filler metal come into contact during brazing, the brazing filler metal will be less likely to wet and spread over the sacrificial anode material, which may make it difficult to form a sound brazing joint.

[0010] As described above, the clad material of Patent Document 1 still has room for improvement in terms of improving strength, corrosion resistance, and brazeability in a balanced manner.

[0011] The present invention has been made in view of the above background, and aims to provide a brazing sheet that is excellent in strength, corrosion resistance and brazing properties. [Means for solving the problem]

[0012] One aspect of the present invention is a core material having a chemical composition comprising Si (silicon): 0.30 mass% or more and 1.0 mass% or less, Cu (copper): 0.40 mass% or more and 1.0 mass% or less, Mn (manganese): 1.0 mass% or more and 2.0 mass% or less, and Mg (magnesium): 0.30 mass% or more and 0.90 mass% or less, with the balance being Al (aluminum) and unavoidable impurities, and having a fibrous structure in the metal structure; It has a chemical composition containing Si: 0.3 mass% or more and 1.0 mass% or less, Mn: 1.3 mass% or more and 2.0 mass% or less, and the balance being Al and unavoidable impurities, an intermediate material made of an aluminum alloy having a pitting potential lower than that of the core material and laminated on one surface of the core material; A brazing filler metal having a chemical composition containing 11 mass% or more and 13 mass% or less of Si, with the remainder being Al and unavoidable impurities, and having a thickness of 18 μm or more, laminated on the intermediate material; Zn (zinc): 3.0 mass% or more and 8.0 mass% or less and Mn: 0 mass% or more 0.40 % by mass or less, with the remainder being Al and unavoidable impurities; and a sacrificial anode material having a thickness of 20 μm or more and laminated on the other surface of the core material, The total thickness of the core material, the intermediate material, the brazing material, and the sacrificial anode material is 120 μm or more and 350 μm or less, The brazing sheet has a thickness of the core material that is 55% or more of the total thickness of the core material, the intermediate material, the brazing material, and the sacrificial anode material.

[0013] Another aspect of the present invention is a core material having a chemical composition containing Si: 0.3% by mass or more and 1.0% by mass or less, Cu: 0.4% by mass or more and 1.0% by mass or less, Mn: 1.0% by mass or more and 2.0% by mass or less, and Mg: 0.30% by mass or more and 0.90% by mass or less, with the balance being Al and unavoidable impurities, and having a fibrous structure in its metal structure; an intermediate material made of an aluminum alloy having a chemical composition containing Si: 0.3% by mass or more and 1.0% by mass or less, Mn: 1.0% by mass or more and 2.0% by mass or less, with the balance being Al and unavoidable impurities, and having a pitting potential lower than that of the core material, and laminated on one surface of the core material; A brazing filler metal having a chemical composition containing 11 mass% or more and 13 mass% or less of Si, with the remainder being Al and unavoidable impurities, and having a thickness of 18 μm or more, laminated on the intermediate material; a sacrificial anode material having a chemical composition containing Zn: 3.0% by mass or more and 8.0% by mass or less, Mn: 0% by mass or more and 0.50% by mass or less, with the balance being Al and unavoidable impurities, and having a thickness of 20 μm or more, laminated on the other surface of the core material; The total thickness of the core material, the intermediate material, the brazing material, and the sacrificial anode material is 120 μm or more and 350 μm or less, The thickness of the core material is 55% or more of the total thickness of the core material, the intermediate material, the brazing material, and the sacrificial anode material. A method for manufacturing a brazing sheet, an aluminum ingot preparation step of preparing a plurality of aluminum ingots including a core ingot that will become the core material, an intermediate ingot that will become the intermediate material, a brazing material ingot that will become the brazing material, and a sacrificial anode material ingot that will become the sacrificial anode material; a lamination step of superposing the intermediate material block and the brazing material block on one surface of the core material block and superposing the sacrificial anode material block on the other surface to prepare a clad block; a clad rolling step of hot rolling the clad ingot to integrate a plurality of the aluminum ingots to produce a clad plate; a hot rolling step of hot rolling the clad plate; Next, a cold rolling step of subjecting the clad plate to one or more cold rolling processes; The method for manufacturing a brazing sheet includes a final annealing step in which, after the cold rolling step is completed, the clad sheet is annealed by holding it at a temperature of 180°C or higher and 350°C or lower for 1 hour or higher and 10 hours or lower. [Effects of the Invention]

[0014] In the brazing sheet, the intermediate material and the brazing filler material are laminated on one side of the core material, and a sacrificial anode material is laminated on the other side of the core material. Furthermore, the thicknesses of the core material, intermediate material, brazing filler material, and sacrificial anode material in the brazing sheet each satisfy the specific relationship. By optimizing not only the chemical composition of each layer constituting the brazing sheet but also the metal structure and thickness, the strength of each layer can be increased and the brazing sheet can be age-hardened after brazing. Therefore, the brazing sheet can easily achieve high strength.

[0015] Furthermore, since the brazing sheet can increase its strength after brazing by age hardening, the Mn content in the sacrificial anode material can be relatively low. By keeping the Mn content in the sacrificial anode material within the above-mentioned specific range, a sound brazed joint can be easily formed even when the sacrificial anode material and the brazing filler metal come into contact with each other.

[0016] In addition, in the brazing sheet, the pitting potential of the intermediate material and the pitting potential of the sacrificial anode material are lower than the pitting potential of the core material, so that the intermediate material and the sacrificial anode material function as sacrificial anodes for the core material, and corrosion of the core material can be suppressed, whether corrosion progresses from the brazing material side or the sacrificial anode material side.

[0017] As a result of the above, the brazing sheet has excellent balance of strength, corrosion resistance and brazeability.

[0018] Furthermore, according to the method for producing a brazing sheet of the above aspect, the brazing sheet can be easily obtained. [Brief explanation of the drawings]

[0019] [Figure 1] FIG. 1 is a cross-sectional view showing a main part of a brazing sheet according to an embodiment of the present invention. [Figure 2] FIG. 2 is a perspective view of a heat exchanger tube made of a brazing sheet. [Figure 3] FIG. 3 is a perspective view of a mini-core specimen in the example. DETAILED DESCRIPTION OF THE INVENTION

[0020] (Brazing sheet) The brazing sheet has a core material, an intermediate material laminated on one side of the core material, a brazing material laminated on the intermediate material, and a sacrificial anode material laminated on the other side of the core material. The brazing sheet is composed of four layers: the core material, the intermediate material, the brazing material, and the sacrificial anode material. Each layer that makes up the brazing sheet will be described in detail below.

[0021] [Heartwood] The core material is made of an aluminum alloy having a chemical composition containing Si: 0.30 to 1.0 mass %, Cu: 0.40 to 1.0 mass %, Mn: 1.0 to 2.0 mass %, Mg: 0.30 to 0.90 mass %, and the balance being Al and unavoidable impurities. The metal structure of the core material before brazing contains a fibrous structure.

[0022] ·Si: 0.30 mass% or more and 1.0 mass% or less The core material contains 0.30% by mass or more and 1.0% by mass or less of Si as an essential component. Some of the Si in the core material exists as Al-Fe-Mn-Si intermetallic compounds together with Fe and Mn, and the remainder of the Si in the core material is solid-dissolved in the core material. By setting the Si content in the core material within the above-mentioned specific range, the effects of dispersion strengthening by the Al-Fe-Mn-Si intermetallic compounds and solid-solution strengthening by the Si dissolved in the core material can be sufficiently enhanced, thereby improving the strength of the core material.

[0023] Furthermore, Si in the core material has the effect of precipitating Mg2Si in the core material through aging after the brazing heat is completed, thereby improving the strength of the brazing sheet. By setting the Si content in the core material within the above-mentioned specific range, it is possible to increase the increase in the strength of the brazing sheet due to age hardening after brazing.

[0024] From the viewpoint of further enhancing the aforementioned effect of improving the strength of the core material and the effect of increasing the amount of increase in strength due to age hardening, the Si content in the core material is preferably 0.35% by mass or more. If the Si content in the core material is less than 0.30% by mass, the aforementioned effect of improving strength will be insufficient and the amount of increase in strength due to age hardening will be small, which may lead to a decrease in the strength of the core material.

[0025] On the other hand, if the Si content in the core material is excessively high, the melting point of the core material will decrease, and the core material may become more likely to melt during brazing heating. By setting the Si content in the core material to 1.0 mass% or less, preferably 0.60 mass% or less, and more preferably 0.55 mass% or less, melting of the core material during brazing heating can be easily avoided.

[0026] ·Cu: 0.40 mass% or more and 1.0 mass% or less The core material contains 0.40% by mass or more and 1.0% by mass or less of Cu as an essential component. Cu dissolves in the core material and has the effect of improving the strength of the core material through solid solution strengthening. By setting the Cu content in the core material within the above-mentioned specific range, the strength of the core material can be improved.

[0027] To further enhance the aforementioned strength-improving effect, the Cu content in the core material is preferably 0.50% by mass or more, and more preferably 0.60% by mass or more. If the Cu content in the core material is less than 0.40% by mass, the aforementioned strength-improving effect may be insufficient, which may result in a decrease in the strength of the core material.

[0028] On the other hand, if the Cu content in the core material is excessively high, the melting point of the core material will decrease, and the core material may become more likely to melt during brazing heating. By setting the Cu content in the core material to 1.0 mass% or less, preferably 0.90 mass% or less, melting of the core material during brazing heating can be easily avoided.

[0029] ·Mn: 1.0 mass% or more and 2.0 mass% or less The core material contains 1.0% by mass or more and 2.0% by mass or less of Mn as an essential component. Some of the Mn in the core material exists as an Al-Fe-Mn-Si intermetallic compound together with Si and Fe, and the remainder of the Mn in the core material is solid-solved in the core material. By setting the Mn content in the core material within the above-mentioned specific range, the effects of dispersion strengthening by the Al-Fe-Mn-Si intermetallic compound and solid-solution strengthening by the Mn solid-solved in the core material can be sufficiently enhanced, thereby improving the strength of the core material. Furthermore, by setting the Mn content in the core material within the above-mentioned specific range, the potential of the core material can be made nobler and the solidus temperature of the core material can be increased.

[0030] If the Mn content in the core material is less than 1.0 mass %, the above-mentioned effects may not be fully obtained.

[0031] On the other hand, if the Mn content in the core material is excessively high, large intermetallic compounds are likely to form during casting, which may result in a decrease in plastic workability. In this case, the Si dissolved in the core material is likely to be consumed along with the formation of Al-Fe-Mn-Si intermetallic compounds in the core material. If the amount of Si dissolved in the core material decreases, it becomes difficult to form Mg2Si during aging after brazing heat, which may result in a decrease in the increase in strength due to age hardening. The above-mentioned problems can be easily avoided by limiting the Mn content in the core material to 2.0 mass% or less, preferably 1.8 mass% or less, and more preferably 1.4 mass% or less.

[0032] ·Mg: 0.30 mass% or more and 0.90 mass% or less The core material contains 0.30% by mass or more and 0.90% by mass or less of Mg as an essential component. The Mg in the core material forms Mg2Si during aging after the brazing heat, and has the effect of improving the strength of the brazing sheet after the brazing heat by age hardening. By making the Mg content in the core material 0.30% by mass or more, preferably 0.35% by mass or more, it is possible to increase the increase in strength of the brazing sheet due to age hardening after the brazing heat. If the Mg content in the core material is less than 0.30% by mass, the increase in strength due to age hardening may be small.

[0033] On the other hand, if the Mg content in the core material is excessively high, the core material may be more likely to melt during brazing heating. By setting the Mg content in the core material to 0.90 mass% or less, preferably 0.60 mass% or less, and more preferably 0.55 mass% or less, melting of the core material during brazing heating can be easily avoided.

[0034] The core material of the brazing sheet may contain, in addition to the essential components Si, Mn, Cu, and Mg, one or more optional elements selected from the group consisting of Fe (iron): 0.05% by mass or more and 1.0% by mass or less, Ti (titanium): 0.05% by mass or more and 0.30% by mass or less, Cr (chromium): 0.05% by mass or more and 0.30% by mass or less, V (vanadium): 0.05% by mass or more and 0.30% by mass or less, and Zr (zirconium): 0.05% by mass or more and 0.30% by mass or less.

[0035] ·Fe: 0.05 mass% or more and 1.0 mass% or less The core material may contain 0.05% by mass or more and 1.0% by mass or less of Fe as an optional component. The Fe in the core material forms an Al-Fe-Mn-Si intermetallic compound with Si and Mn, further improving the strength of the core material through precipitation strengthening. By setting the Fe content in the core material within the above-mentioned specific range, an appropriate amount of Al-Fe-Mn-Si intermetallic compound can be formed in the core material. As a result, the strength of the core material is further improved, and the amount of Si dissolved in the core material is sufficiently increased, thereby increasing the increase in the strength of the brazing sheet after brazing heating.

[0036] Furthermore, by setting the Fe content in the core material within the above-mentioned specific range, it is possible to easily avoid a decrease in plastic workability due to the formation of coarse intermetallic compounds. From the viewpoint of more reliably avoiding the formation of coarse intermetallic compounds in the core material, the Fe content in the core material is more preferably 0.70 mass% or less, and even more preferably 0.40 mass% or less.

[0037] Furthermore, by setting the Fe content in the core material to 0.05 mass% or more, it is possible to use relatively inexpensive base metal containing a certain amount of Fe as the base metal for producing the core material, which makes it easier to prevent increases in the material cost of the brazing sheet.

[0038] ·Ti: 0.05 mass% or more and 0.30 mass% or less, Cr: 0.05 mass% or more and 0.30 mass% or less, Zr: 0.05 mass% or more and 0.30 mass% or less The core material may contain, as optional components, one or more of the following elements: 0.05% by mass to 0.30% by mass of Ti, 0.05% by mass to 0.30% by mass of Cr, and 0.05% by mass to 0.30% by mass of Zr. These elements dissolve in the core material and have the effect of improving the strength of the core material through solid solution strengthening.

[0039] By setting the Ti, Cr, and Zr contents in the core material to 0.05% by mass or more, and more preferably 0.10% by mass or more, respectively, the strength of the core material can be further improved. Also, by setting the Ti, Cr, and Zr contents in the core material to 0.30% by mass or less, and more preferably 0.20% by mass or less, respectively, a decrease in plastic workability due to the formation of coarse intermetallic compounds can be easily avoided.

[0040] ·V: 0.05 mass% or more and 0.30 mass% or less The core material may contain 0.05% by mass or more and 0.30% by mass or less of V as an optional component. V dissolves in the core material and has the effect of improving the strength of the core material through solid solution strengthening and the effect of improving the corrosion resistance of the core material. By setting the V content in the core material within the above-mentioned specific range, the strength and corrosion resistance of the core material can be further improved. Furthermore, by setting the V content in the core material within the above-mentioned specific range, it is possible to easily avoid a decrease in plastic workability due to the formation of coarse intermetallic compounds. From the viewpoint of further enhancing these effects, the V content in the core material is more preferably 0.10% by mass or more and 0.20% by mass or less.

[0041] Inevitable impurities In addition to the essential and optional components described above, the core material contains unavoidable impurities that are inevitably mixed in during the manufacturing process. The content of the elements that constitute the unavoidable impurities is 0.05% by mass or less for each element, and the total content is 0.15% by mass or less.

[0042] Metal structure before brazing The metal structure of the core material in the brazing sheet before brazing includes a fibrous structure. That is, the metal structure of the core material before brazing may be composed of both a fibrous structure and an equiaxed structure, or may be composed of only a fibrous structure. By forming the metal structure of the core material before brazing in this manner, the crystal grains of the core material after brazing heat can be refined. As a result, the strength of the core material after brazing heat can be further improved. From the viewpoint of more reliably obtaining such effects, it is preferable that the metal structure of the core material be composed of only a fibrous structure.

[0043] The term "fibrous structure" refers to a structure having numerous crystal grains that have been stretched in the processing direction by rolling, extrusion, forging, or other wrought processes. When a cross section parallel to the processing direction is observed using a metallurgical microscope at a magnification of 25 to 100 times, the fibrous structure is observed as a streaky pattern extending in the processing direction. The term "equixed structure" refers to a structure having numerous equiaxed crystal grains. When a cross section parallel to the processing direction is observed using a metallurgical microscope at a magnification of 25 to 100 times, the equiaxed structure is observed as a granular pattern with a relatively small difference between the major and minor axes.

[0044] Metal structure after brazing heating The metal structure of the core material after brazing heat is preferably an equiaxed structure with an average crystal grain size of less than 60 μm. By refining the crystal grains of the core material after brazing heat in this way, the strength of the brazing sheet after brazing heat can be further improved. Specifically, in the above-mentioned "brazing heat," heating is performed so that the temperature of the brazing sheet is in the range of 577°C to 600°C for 3 minutes.

[0045] Thickness The thickness of the core material in the brazing sheet is 55% or more of the total thickness of the core material, the intermediate material, the brazing filler material, and the sacrificial anode material. By setting the thickness of the core material in the brazing sheet within this specific range, it is possible to ensure a sufficient thickness of the core material and improve the strength of the brazing sheet.

[0046] [Intermediate material] An intermediate material is laminated on one surface of the core material. The intermediate material is made of an aluminum alloy with a pitting potential lower than that of the core material. As a result, even if corrosion progresses from the brazing filler metal side and the core material is exposed, the intermediate material remaining on the core material can function as a sacrificial anode for the core material, thereby suppressing corrosion of the core material.

[0047] The aluminum alloy constituting the intermediate material may have a chemical composition that contains, for example, Si: 0.30 mass% or more and 1.0 mass% or less, Mn: 1.0 mass% or more and 2.0 mass% or less, with the remainder being Al and unavoidable impurities.

[0048] ·Si: 0.30 mass% or more and 1.0 mass% or less The intermediate material contains 0.30% by mass or more and 1.0% by mass or less of Si as an essential component. Like Si in the core material, Si in the intermediate material has the effect of improving the strength of the intermediate material through dispersion strengthening and solid solution strengthening. By setting the Si content in the intermediate material within the above-mentioned specific range, the effects of dispersion strengthening and solid solution strengthening can be sufficiently enhanced, and the strength of the intermediate material before brazing can be improved.

[0049] Furthermore, since the intermediate material is adjacent to the core material, Mg and Si diffuse from the core material to the intermediate material during brazing heating. The Si in the intermediate material, together with the Mg and Si supplied from the core material, can precipitate MgSi in the intermediate material by aging after brazing heating is completed. By setting the Si content in the intermediate material within the above-mentioned specific range, the increase in strength of the intermediate material due to age hardening after brazing heating can be increased.

[0050] From the viewpoint of further enhancing the aforementioned effect of improving the strength of the brazing filler metal and the effect of increasing the amount of increase in strength due to age hardening, the Si content in the intermediate material is preferably 0.40 mass% or more. If the Si content in the intermediate material is less than 0.30 mass%, the aforementioned effect of improving strength becomes insufficient and the amount of increase in strength due to age hardening becomes small, which may lead to a decrease in the strength of the intermediate material.

[0051] On the other hand, if the Si content in the intermediate material is excessively high, the melting point of the intermediate material will decrease, and the intermediate material may become more likely to melt during brazing heating. By setting the Si content in the intermediate material to 1.0 mass% or less, preferably 0.80 mass% or less, melting of the intermediate material during brazing heating can be easily avoided.

[0052] ·Mn: 1.0 mass% or more and 2.0 mass% or less The intermediate material contains 1.0 mass % or more and 2.0 mass % or less of Mn as an essential component. Like the Mn in the core material, the Mn in the intermediate material acts to improve the strength of the intermediate material through solid solution strengthening and dispersion strengthening. By setting the Mn content in the intermediate material within the above-mentioned specific range, the strength of the intermediate material can be improved. Furthermore, the Mn in the intermediate material acts to increase the deformation resistance during hot rolling. Therefore, by setting the Mn content in the intermediate material within the above-mentioned specific range, the difference between the deformation resistance of the core material and the deformation resistance of the intermediate material during the brazing sheet manufacturing process can be reduced, and the variation in the thickness of each layer in the final brazing sheet can be reduced.

[0053] To further enhance the aforementioned effects, the Mn content in the intermediate material is preferably 1.3 mass% or more, and more preferably 1.5 mass% or more. If the Mn content in the intermediate material is less than 1.0 mass%, the aforementioned effects may not be fully achieved.

[0054] On the other hand, if the Mn content in the intermediate material is excessively high, large intermetallic compounds are likely to be formed during casting, which may lead to a decrease in plastic workability. The above-mentioned problem can be easily avoided by setting the Mn content in the intermediate material to 2.0 mass% or less, preferably 1.8 mass% or less.

[0055] In addition to the essential components Si and Mn, the intermediate material of the brazing sheet may contain, as optional components, one or more elements selected from the group consisting of Zn (zinc): more than 0% by mass and not more than 3.0% by mass, Fe: 0.05% by mass or more and not more than 1.0% by mass, Ti: 0.05% by mass or more and not more than 0.30% by mass, Cr: 0.05% by mass or more and not more than 0.30% by mass, V: 0.05% by mass or more and not more than 0.30% by mass, Zr: 0.05% by mass or more and not more than 0.30% by mass, In (indium): more than 0% by mass and not more than 0.10% by mass, Sn (tin): more than 0% by mass and not more than 0.10% by mass, and Ni (nickel): 0.05% by mass or more and not more than 2.0% by mass.

[0056] ·Zn: More than 0% by mass and 3.0% by mass or less The intermediate material may contain Zn in an amount of more than 0 mass% and not more than 3.0 mass% as an optional component. Zn in the intermediate material has the effect of making the pitting potential of the intermediate material less noble. By adding 3.0 mass% or less of Zn to the intermediate material, the potential difference between the core material and the intermediate material can be sufficiently increased, thereby further improving corrosion resistance against corrosion from the brazing material side. From the viewpoint of further enhancing the sacrificial corrosion protection effect of the intermediate material, the Zn content in the intermediate material is preferably 0.5 mass% or more, and more preferably 1.0 mass% or more.

[0057] Furthermore, by setting the Zn content in the intermediate material to 3.0 mass% or less, preferably 2.5 mass% or less, and more preferably 2.0 mass% or less, it is possible to slow the corrosion rate of the intermediate material itself while exerting a sacrificial corrosion protection effect on the core material, thereby allowing the sacrificial corrosion protection effect on the core material to be exerted for a longer period of time.

[0058] ·Fe: 0.05 mass% or more and 1.0 mass% or less The intermediate material may contain 0.05% by mass or more and 1.0% by mass or less of Fe as an optional component. The effect of Fe in the intermediate material is similar to that of Fe in the core material. By making the Fe content in the intermediate material 0.05% by mass or more, more preferably 0.10% by mass or more, the effects of dispersion strengthening and solid solution strengthening can be further enhanced, and the strength of the intermediate material can be further improved. In addition, in this case, a relatively inexpensive base metal containing a certain amount of Fe can be used as the base metal for producing the intermediate material. This is expected to further reduce the material cost of the brazing sheet.

[0059] Furthermore, by setting the Fe content in the intermediate material to 1.0 mass % or less, more preferably 0.30 mass % or less, it is possible to easily avoid a decrease in plastic workability due to the formation of coarse intermetallic compounds.

[0060] ·Ti: 0.05 mass% or more and 0.30 mass% or less, Cr: 0.05 mass% or more and 0.30 mass% or less, Zr: 0.05 mass% or more and 0.30 mass% or less The intermediate material may contain, as optional components, one or more of the following elements: 0.05% by mass to 0.30% by mass of Ti, 0.05% by mass to 0.30% by mass of Cr, and 0.05% by mass to 0.30% by mass of Zr. The effects of Ti, Cr, and Zr in the intermediate material and the reasons for limiting the contents of these elements are the same as those for the core material.

[0061] That is, by setting the Ti content, Cr content, and Zr content in the intermediate material to 0.05 mass% or more, and more preferably 0.10 mass% or more, respectively, the strength of the intermediate material can be further improved. Also, by setting the Ti content, Cr content, and Zr content in the intermediate material to 0.30 mass% or less, and more preferably 0.20 mass% or less, respectively, it is possible to easily avoid a decrease in plastic workability due to the formation of coarse intermetallic compounds.

[0062] ·V: 0.05 mass% or more and 0.30 mass% or less The intermediate material may contain 0.05% by mass or more and 0.30% by mass or less of V as an optional component. The effects of V in the intermediate material and the reasons for limiting the V content are the same as those for the core material. That is, by setting the V content in the intermediate material to 0.05% by mass or more, more preferably 0.10% by mass or more, the strength and corrosion resistance of the intermediate material can be further improved. Furthermore, by setting the V content in the intermediate material to 0.30% by mass or less, more preferably 0.20% by mass or less, it is possible to easily avoid a decrease in plastic workability due to the formation of coarse intermetallic compounds.

[0063] In: over 0% by mass and up to 0.10% by mass, Sn: over 0% by mass and up to 0.10% by mass The intermediate material may contain, as optional components, one or two of more than 0% by mass but not more than 0.10% by mass of In and more than 0% by mass but not more than 0.10% by mass of Sn. These elements have the effect of making the pitting potential of the intermediate material less noble. By adding 0.10% by mass or less of In and / or 0.10% by mass or less of Sn to the intermediate material, the sacrificial corrosion protection effect of the intermediate material can be further enhanced, and the corrosion resistance against corrosion from the brazing material side can be further improved. From the viewpoint of ensuring that the sacrificial corrosion protection effect of the intermediate material is exerted for a longer period of time, it is more preferable that the In content and Sn content in the intermediate material are each 0.05% by mass or less.

[0064] ·Ni: 0.05 mass% or more and 2.0 mass% or less The intermediate material may contain 0.05% by mass or more and 2.0% by mass or less of Ni as an optional component. By adding Ni in the above-mentioned specific range to the intermediate material, Al-Ni-based intermetallic compounds and Al-Fe-Ni-based intermetallic compounds can be formed in the intermediate material. These intermetallic compounds have a more noble pitting potential than the Al matrix of the intermediate material, so that at the contact points between the intermetallic compounds and the Al matrix, the Al matrix corrodes before the intermetallic compounds. Furthermore, by dispersing the intermetallic compounds, which serve as corrosion initiation sites, in the intermediate material, the progression of corrosion in the depth direction of the intermediate material can be suppressed.

[0065] To further enhance the above-mentioned effects, the Ni content in the intermediate material is preferably 0.10% by mass or more. Furthermore, by setting the Ni content in the intermediate material to 2.0% by mass or less, more preferably 1.5% by mass or less, it is possible to more easily avoid a decrease in plastic workability due to the formation of coarse intermetallic compounds.

[0066] Other ingredients In addition to the essential and optional components described above, the intermediate material contains unavoidable impurities that are inevitably mixed in during the manufacturing process of the intermediate material. The content of the elements that constitute the unavoidable impurities is 0.05% by mass or less for each element, and the total content is 0.15% by mass or less.

[0067] The intermediate material may contain Cu as an inevitable impurity, but Cu in the intermediate material has the effect of making the potential of the intermediate material nobler. Therefore, if the Cu content is excessively high, the potential difference between the intermediate material and the core material tends to become small. From the viewpoint of more reliably avoiding a decrease in the sacrificial corrosion protection effect of the intermediate material due to Cu, the Cu content in the intermediate material is preferably less than 0.05 mass%, and more preferably 0.03 mass% or less.

[0068] Thickness The intermediate material preferably has a thickness of 12 μm or more. By making the thickness of the intermediate material 12 μm or more, the sacrificial corrosion protection effect of the intermediate material can be maintained for a longer period of time, and corrosion resistance against corrosion from the brazing filler metal can be further improved. In this case, the amount of Mg that reaches the surface of the brazing filler metal from the core material during brazing heat is reduced, making it easier to avoid deterioration of brazing properties due to the reaction between Mg and flux. Furthermore, by making the thickness of the intermediate material 12 μm or more, the amount of Si that reaches the core material from the brazing filler metal during brazing heat is reduced, making it easier to avoid erosion of the core material, i.e., the phenomenon in which Si that reaches the core material uses the grain boundaries of the core material as a diffusion path to corrode the core material. From the viewpoint of further enhancing these effects, it is more preferable that the thickness of the intermediate material be 18 μm or more.

[0069] [Brazing material] A brazing filler metal is laminated on the intermediate material. The brazing filler metal is made of an aluminum alloy having a chemical composition containing 11% by mass or more and 13% by mass or less of Si, with the remainder being Al and unavoidable impurities.

[0070] ·Si: 11% by mass or more and 13% by mass or less The brazing filler metal contains 11% by mass or more and 13% by mass or less of Si as an essential component. Si in the brazing filler metal has the effect of generating brazing material during brazing heating and forming a brazed joint.

[0071] In addition to the thin overall thickness of the brazing sheet, the thicknesses of the intermediate material, brazing filler metal, and sacrificial anode material are also thin, so Mg in the core material easily diffuses into these layers during the temperature rise process during brazing heating. However, if an excessive amount of Mg diffuses from the core material and reaches the surface of the brazing filler metal, this is likely to lead to deterioration of brazing performance in both flux-based and flux-free brazing.

[0072] That is, in brazing using a flux, Mg that reaches the surface of the brazing filler metal reacts with the flux, resulting in the consumption of the flux. As a result, the oxide film is not sufficiently destroyed by the flux, which tends to inhibit the wetting and spreading of the brazing filler metal. In addition, in brazing without a flux, Mg that reaches the surface of the brazing filler metal reacts with oxygen and moisture in the atmosphere to form a thick oxide film, which tends to inhibit the wetting and spreading of the brazing filler metal.

[0073] To avoid deterioration of brazing properties due to Mg reaching the brazing filler metal surface, it is desirable to form a brazed joint with the mating material while the amount of Mg reaching the brazing filler metal surface is relatively small. The diffusion rate of Mg increases as the heating temperature increases. In particular, at temperatures higher than the eutectic temperature, liquid brazing filler metal is generated, and the diffusion rate of Mg is significantly faster than before the liquid brazing filler metal is generated. Therefore, it is important to quickly liquidize the entire brazing filler metal after the heating temperature reaches the eutectic temperature and form a brazed joint with the mating material before the wetting and spreading of the brazing filler metal is inhibited. Furthermore, the higher the liquid fraction of the brazing filler metal when the heating temperature reaches the eutectic temperature, the easier it is to supply the brazing filler metal to the area where the brazing filler metal is to be formed before it is affected by Mg diffusing from the core material, and the thinner the brazing filler metal can be.

[0074] Based on this concept, the Si content in the brazing sheet is set to 11% by mass or more in the brazing filler metal. By setting the Si content in the brazing filler metal to 11% by mass or more, the liquid phase ratio immediately after the eutectic temperature is exceeded during brazing heating can be sufficiently increased. As a result, a sound brazed joint can be easily formed with the mating material before the Mg that has reached the surface of the brazing filler metal deteriorates brazing properties. If the Si content in the brazing filler metal is less than 11% by mass, it may be difficult to form a sound brazed joint with the mating material.

[0075] On the other hand, if the Si content in the brazing filler metal is too high, the amount of Si that diffuses into the mating material during brazing heat will be too large, which may cause the mating material to melt. By setting the Si content in the brazing filler metal to 13.0 mass% or less, preferably 12.5 mass% or less, it is possible to more reliably avoid melting of the mating material while ensuring excellent brazing properties.

[0076] In addition to Si as an essential component, the brazing material of the brazing sheet may contain, as optional components, one or more elements selected from the group consisting of Fe: 0.05% by mass or more and 1.0% by mass or less, Zn: more than 0% by mass and 4.0% by mass or less, Ti: 0.05% by mass or more and 0.30% by mass or less, Cr: 0.05% by mass or more and 0.30% by mass or less, V: 0.05% by mass or more and 0.30% by mass or less, Zr: 0.05% by mass or more and 0.30% by mass or less, In: more than 0% by mass and 0.10% by mass or less, Sn: more than 0% by mass and 0.10% by mass or less, Na (sodium): 0.001% by mass or more and 0.050% by mass or less, and Sr (strontium) 0.001% by mass or more and 0.050% by mass or less.

[0077] ·Fe: 0.05 mass% or more and 1.0 mass% or less The brazing filler metal may contain 0.05% by mass or more and 1.0% by mass or less of Fe as an optional component. An excessively high Fe content in the brazing filler metal may result in a deterioration in brazability. However, by limiting the Fe content in the brazing filler metal to 1.0% by mass or less, more preferably 0.50% by mass or less, the deterioration in brazability due to Fe can be easily avoided. Therefore, a brazing filler metal having an Fe content within the above-mentioned specific range has good brazability and can easily form a sound brazed joint with a mating material.

[0078] Furthermore, by setting the Fe content in the brazing filler metal to 0.05 mass% or more, and more preferably 0.10 mass% or more, it is possible to use a relatively inexpensive base metal containing a certain amount of Fe as the base metal for producing the brazing filler metal, which makes it easier to prevent an increase in the material cost of the brazing sheet.

[0079] ·Zn: More than 0 mass% and 4.0 mass% or less The brazing filler metal may contain more than 0 mass% and 4.0 mass% or less Zn as an optional component. Zn in the brazing filler metal has the effect of lowering the pitting corrosion potential of the brazing filler metal. By adding 4.0 mass% or less Zn to the brazing filler metal, the potential difference between the core material and the brazing filler metal can be made sufficiently large, allowing the brazing filler metal to function as a sacrificial anode for the core material. As a result, corrosion resistance against corrosion from the brazing filler metal side can be further improved.

[0080] The Zn content in the brazing filler metal is more preferably 1.0 mass% or less, and even more preferably 0.5 mass% or less. In this case, the brazing filler metal can exhibit a sacrificial corrosion protection effect on the core material while slowing down the corrosion rate of the brazing filler metal itself. This allows the sacrificial corrosion protection effect on the core material to be exhibited for a longer period of time.

[0081] ·Ti: 0.05 mass% or more and 0.30 mass% or less, Cr: 0.05 mass% or more and 0.30 mass% or less, Zr: 0.05 mass% or more and 0.30 mass% or less The brazing filler metal may contain, as optional components, one or more of 0.05% by mass to 0.30% by mass of Ti, 0.05% by mass to 0.30% by mass of Cr, and 0.05% by mass to 0.30% by mass of Zr. The effects of Ti, Cr, and Zr in the brazing filler metal and the reasons for limiting the contents of these elements are the same as those for the core material.

[0082] That is, by setting the Ti content, Cr content, and Zr content in the brazing filler metal to 0.05 mass% or more, and more preferably 0.10 mass% or more, respectively, the strength of the brazing filler metal can be further improved. Also, by setting the Ti content, Cr content, and Zr content in the brazing filler metal to 0.30 mass% or less, and more preferably 0.20 mass% or less, respectively, the deterioration of plastic workability due to the formation of coarse intermetallic compounds can be easily avoided.

[0083] ·V: 0.05 mass% or more and 0.30 mass% or less The brazing filler metal may contain 0.05% by mass or more and 0.30% by mass or less of V as an optional component. The effects of V in the brazing filler metal and the reasons for limiting the V content are the same as those for the core metal. That is, by setting the V content in the brazing filler metal to 0.05% by mass or more, more preferably 0.10% by mass or more, the strength and corrosion resistance of the brazing filler metal can be further improved. Furthermore, by setting the V content in the brazing filler metal to 0.30% by mass or less, more preferably 0.20% by mass or less, it is possible to easily avoid a decrease in plastic workability due to the formation of coarse intermetallic compounds.

[0084] In: over 0% by mass and up to 0.10% by mass, Sn: over 0% by mass and up to 0.10% by mass The brazing filler metal may contain, as optional components, one or two of more than 0% by mass but not more than 0.10% by mass of In and more than 0% by mass but not more than 0.10% by mass of Sn. The effects of In and Sn in the brazing filler metal and the reasons for limiting the contents of these elements are the same as those for the intermediate material. That is, by adding 0.10% by mass or less of In and / or 0.10% by mass or less of Sn to the brazing filler metal, the corrosion resistance against corrosion from the brazing filler metal side can be further improved. From the viewpoint of ensuring that the sacrificial corrosion protection effect of the brazing filler metal is exerted for a longer period of time, it is more preferable that the In content and Sn content in the brazing filler metal are each 0.05% by mass or less.

[0085] ·Na: 0.001 mass% or more and 0.050 mass% or less, Sr: 0.001 mass% or more and 0.050 mass% or less The brazing filler metal may contain one or two of 0.001% by mass to 0.050% by mass of Na and 0.001% by mass to 0.050% by mass of Sr as optional components. By adding 0.001% by mass to 0.050% by mass of Na and / or 0.001% by mass to 0.050% by mass of Sr to the brazing filler metal, the Si particles in the brazing filler metal can be made finer. From the viewpoint of further enhancing this effect, the Na content and Sr content in the brazing filler metal are preferably each 0.003% by mass or more.

[0086] On the other hand, if the Na content or Sr content in the brazing filler metal is excessively high, the oxide film formed on the surface of the brazing filler metal during brazing heating tends to become thick, which may lead to deterioration of brazing properties. This problem can be easily avoided by setting the Na content and Sr content in the brazing filler metal to 0.050 mass% or less, respectively. From the same perspective, it is more preferable that the Na content and Sr content in the brazing filler metal are each 0.020 mass% or less.

[0087] Other ingredients In addition to the essential and optional components described above, the brazing filler metal contains unavoidable impurities that are inevitably mixed in during the manufacturing process of the brazing filler metal. The content of the elements as unavoidable impurities is 0.05% by mass or less for each element, and the total content is 0.15% by mass or less.

[0088] Thickness The thickness of the brazing filler metal is 18 μm or more. By making the brazing filler metal thickness 18 μm or more, a sufficient amount of brazing filler metal is generated during brazing heating, making it easy to form a sound brazed joint with the mating material. On the other hand, if the brazing filler metal thickness is excessively large, it becomes difficult to ensure a sufficient thickness of the core material, which may result in a decrease in the strength of the brazing sheet. In addition, in this case, the amount of brazing filler metal generated during brazing heating may be excessive, which may make the core material and the mating material more susceptible to erosion by the brazing filler metal. From the perspective of more reliably avoiding these problems, it is preferable that the thickness of the brazing filler metal be 40 μm or less.

[0089] [Sacrificial anode material] A sacrificial anode material is laminated on the other surface of the core material of the brazing sheet, i.e., the surface on which neither the intermediate material nor the brazing material is provided. The sacrificial anode material is made of an aluminum alloy having a chemical composition containing 3.0% by mass to 8.0% by mass of Zn, 0% by mass to 0.5% by mass of Mn, and the remainder being Al and unavoidable impurities.

[0090] ·Zn: 3.0 mass% or more and 8.0 mass% or less The sacrificial anode material contains 3.0 mass % to 8.0 mass % Zn as an essential component. Zn in the sacrificial anode material has the effect of lowering the pitting corrosion potential of the sacrificial anode material. By setting the Zn content in the sacrificial anode material within the above-mentioned specific range, the potential difference between the core material and the sacrificial anode material can be made sufficiently large, allowing the sacrificial anode material to function as a sacrificial anode for the core material. As a result, corrosion resistance against corrosion from the sacrificial anode material side can be further improved.

[0091] The Zn content in the sacrificial anode material is preferably 4.0% by mass or more. In this case, the sacrificial corrosion protection effect for the core material can be further enhanced. If the Zn content in the sacrificial anode material is less than 3.0% by mass, the potential difference between the core material and the sacrificial anode material becomes small, and the sacrificial corrosion protection effect may become insufficient.

[0092] On the other hand, if the Zn content in the sacrificial anode material is excessively high, the corrosion rate of the sacrificial anode material increases, and the sacrificial anode material is likely to disappear early. By setting the Zn content in the sacrificial anode material to 8.0 mass% or less, preferably 7.0 mass% or less, the corrosion rate of the sacrificial anode material itself can be slowed while the sacrificial corrosion protection effect on the core material is exerted. This allows the sacrificial corrosion protection effect on the core material to be exerted for a longer period of time.

[0093] ·Mn: 0 mass% or more and 0.50 mass% or less The sacrificial anode material may contain 0.50% by mass or less of Mn as an optional component. Like the Mn in the intermediate material, the Mn in the sacrificial anode material improves the strength of the sacrificial anode material through dispersion strengthening and solid-solution strengthening, and also has the effect of increasing deformation resistance during hot rolling. Therefore, adding more than 0% by mass and 0.50% by mass or less of Mn to the sacrificial anode material improves the strength of the sacrificial anode material and reduces the variation in thickness of each layer in the brazing sheet. To further enhance these effects, the Mn content in the sacrificial anode material is preferably 0.10% by mass or more, and more preferably 0.20% by mass or more.

[0094] On the other hand, Mn in the sacrificial anode material has the effect of increasing the pitting potential of the sacrificial anode material. Therefore, if the Mn content in the sacrificial anode material is excessively high, the potential difference between the sacrificial anode material and the core material will decrease, which may lead to a decrease in the sacrificial corrosion protection effect. Furthermore, if the Mn content in the sacrificial anode material is excessively high, the brazing filler metal will not wet and spread easily when it comes into contact with the brazing filler metal during brazing heating, which may lead to a deterioration in brazing properties.

[0095] By setting the Mn content in the sacrificial anode material to 0.50 mass% or less, preferably 0.40 mass% or less, it is possible to easily avoid the above-mentioned problems while obtaining the effects of improving the strength of the sacrificial anode material and reducing the thickness variation.

[0096] In addition to the above-mentioned Zn and Mn, the sacrificial anode material may further contain one or more elements selected from the group consisting of Si: more than 0 mass% and 1.0 mass% or less, Fe: 0.05 mass% or more and 1.0 mass% or less, Ti: 0.05 mass% or more and 0.30 mass% or less, Cr: 0.05 mass% or more and 0.30 mass% or less, V: 0.05 mass% or more and 0.30 mass% or less, Zr: 0.05 mass% or more and 0.30 mass% or less, In: more than 0 mass% and 0.1 mass% or less, Sn: more than 0 mass% and 0.1 mass% or less, and Ni: 0.05 mass% or more and 2.0 mass% or less.

[0097] ·Si: More than 0 mass% and 1.0 mass% or less The sacrificial anode material may contain Si in an amount greater than 0% by mass and not greater than 1.0% by mass as an optional component. Because the core material is in contact with not only the intermediate material but also the sacrificial anode material, Mg and Si diffuse from the core material to the sacrificial anode material during brazing. The Si in the sacrificial anode material, together with the Mg and Si supplied from the core material, can precipitate Mg2Si in the sacrificial anode material by aging after brazing is completed. By setting the Si content in the sacrificial anode material within the above-mentioned specific range, the increase in strength of the sacrificial anode material due to age hardening after brazing can be further enhanced. To further enhance this effect, the Si content in the sacrificial anode material is preferably 0.10% by mass or more, and even more preferably 0.20% by mass or more.

[0098] On the other hand, if the Si content in the sacrificial anode material is excessively high, the sacrificial anode material may melt during brazing heating, which may cause erosion of the core material. By setting the Si content in the sacrificial anode material to 1.0 mass% or less, preferably 0.8 mass% or less, and more preferably 0.7 mass% or less, it is possible to obtain the above-mentioned effects while avoiding melting of the sacrificial anode material.

[0099] ·Fe: 0.05 mass% or more and 1.0 mass% or less The sacrificial anode material may contain 0.05% by mass or more and 1.0% by mass or less of Fe as an optional component. The effect of Fe in the sacrificial anode material is similar to that of Fe in the intermediate. By making the Fe content in the sacrificial anode material 0.05% by mass or more, more preferably 0.10% by mass or more, the effects of dispersion strengthening and solid-solution strengthening can be further enhanced, thereby further improving the strength of the sacrificial anode material. In addition, in this case, a relatively inexpensive base metal containing a certain amount of Fe can be used as the base metal for producing the sacrificial anode material. This makes it easier to suppress increases in the material cost of the brazing sheet.

[0100] Furthermore, by setting the Fe content in the sacrificial anode material to 1.0 mass % or less, more preferably 0.30 mass % or less, it is possible to easily avoid a decrease in plastic workability due to the formation of coarse intermetallic compounds.

[0101] ·Ti: 0.05 mass% or more and 0.30 mass% or less, Cr: 0.05 mass% or more and 0.30 mass% or less, Zr: 0.05 mass% or more and 0.30 mass% or less The sacrificial anode material may contain, as optional components, one or more of 0.05% by mass to 0.30% by mass of Ti, 0.05% by mass to 0.30% by mass of Cr, and 0.05% by mass to 0.30% by mass of Zr. The effects of Ti, Cr, and Zr in the sacrificial anode material and the reasons for limiting the contents of these elements are the same as those for the core material.

[0102] That is, by setting the Ti content, Cr content, and Zr content in the sacrificial anode material to 0.05 mass% or more, and more preferably 0.10 mass% or more, respectively, the strength of the sacrificial anode material can be further improved. Also, by setting the Ti content, Cr content, and Zr content in the sacrificial anode material to 0.30 mass% or less, and more preferably 0.20 mass% or less, respectively, the deterioration of plastic workability due to the formation of coarse intermetallic compounds can be easily avoided.

[0103] ·V: 0.05 mass% or more and 0.30 mass% or less The sacrificial anode material may contain 0.05% by mass or more and 0.30% by mass or less of V as an optional component. The effects of V in the sacrificial anode material and the reasons for limiting the V content are the same as those for the core material. That is, by setting the V content in the sacrificial anode material to 0.05% by mass or more, more preferably 0.10% by mass or more, the strength and corrosion resistance of the sacrificial anode material can be further improved. Furthermore, by setting the V content in the sacrificial anode material to 0.30% by mass or less, more preferably 0.20% by mass or less, it is possible to easily avoid a decrease in plastic workability due to the formation of coarse intermetallic compounds.

[0104] In: over 0% by mass and up to 0.10% by mass, Sn: over 0% by mass and up to 0.10% by mass The sacrificial anode material may contain, as optional components, one or two of more than 0% by mass but not more than 0.10% by mass of In and more than 0% by mass but not more than 0.10% by mass of Sn. The effects of In and Sn in the sacrificial anode material and the reasons for limiting these elements are the same as those for the intermediate material. That is, by adding 0.10% by mass or less of In and / or 0.10% by mass or less of Sn to the sacrificial anode material, it is possible to further improve corrosion resistance against corrosion from the sacrificial anode material side. From the viewpoint of ensuring that the sacrificial anticorrosion effect of the sacrificial anode material is exerted for a longer period of time, it is more preferable that the In content and Sn content in the sacrificial anode material are each 0.05% by mass or less.

[0105] ·Ni: 0.05 mass% or more and 2.0 mass% or less The sacrificial anode material may contain 0.05% by mass or more and 2.0% by mass or less of Ni as an optional component. The effects of Ni in the sacrificial anode material and the reasons for limiting the Ni content are the same as those for the intermediate material. That is, by setting the Ni content in the intermediate material to 0.05% by mass or more, more preferably 0.10% by mass or more, it is possible to suppress the progression of corrosion in the depth direction of the sacrificial anode material. Furthermore, by setting the Ni content in the intermediate material to 2.0% by mass or less, more preferably 1.5% by mass or less, it is possible to more easily avoid a decrease in plastic workability due to the formation of coarse intermetallic compounds.

[0106] Other ingredients In addition to the essential and optional components described above, the sacrificial anode material contains unavoidable impurities that are inevitably mixed in during the manufacturing process of the sacrificial anode material. The content of the elements as unavoidable impurities is 0.05% by mass or less for each element, and the total content is 0.15% by mass or less.

[0107] Thickness The sacrificial anode material has a thickness of 20 μm or more. By making the thickness of the sacrificial anode material 20 μm or more, preferably 25 μm or more, the sacrificial anticorrosion effect of the sacrificial anode material can be exhibited for a longer period of time, and the corrosion resistance against corrosion from the sacrificial anode material side can be further improved. If the thickness of the sacrificial anode material is less than 20 μm, the sacrificial anode material is likely to be lost due to corrosion, and the sacrificial anticorrosion effect may be easily lost early.

[0108] [Brazing sheet thickness] The thickness of the brazing sheet is preferably 120 μm or more and 350 μm or less. By making the thickness of the brazing sheet 120 μm or more, the thickness of the brazing material, intermediate material, and sacrificial anode material can be made appropriately thick while ensuring a sufficient thickness of the core material. This increases the strength of the brazing sheet after brazing and enables excellent corrosion resistance and brazeability to be improved in a balanced manner.

[0109] Furthermore, by making the thickness of the brazing sheet 350 μm or less, the brazing sheet can be suitably used in automotive heat exchangers, for which weight reduction is strongly desired. The thickness of the brazing sheet is more preferably 290 μm or less, even more preferably 250 μm or less, and particularly preferably 220 μm or less. Because the chemical composition, metal structure, and thickness of the core material, intermediate material, brazing filler metal, and sacrificial anode material are optimized, even when the brazing sheet is thinned, it is possible to improve strength, corrosion resistance, and brazeability in a balanced manner. Furthermore, by using a brazing sheet having such a thickness, it is possible to more easily reduce the weight of a heat exchanger while maintaining the performance required for the heat exchanger.

[0110] [Strength of brazing sheet after brazing] The brazing sheet preferably has a strength of 200 MPa or more, and more preferably 210 MPa or more, after brazing heating and subsequent holding at room temperature for 7 days. Brazing sheets with such age-hardening properties are suitable for automotive heat exchangers because they have excellent strength after brazing. Specifically, the "brazing heating" described above is performed so that the temperature of the brazing sheet is in the range of 577°C to 600°C for 3 minutes. "Room temperature" refers to a temperature range of 15°C to 25°C.

[0111] [Uses of brazing sheet] The brazing sheet is suitable for automotive heat exchanger components such as evaporators, condensers, radiators, heaters, intercoolers, and oil coolers, and is particularly suitable for tubes through which aqueous refrigerants such as engine coolants or non-aqueous refrigerants such as fluorocarbon refrigerants flow. Examples of tubes that can be used include brazed tubes in which the brazing sheet is bent into a cylindrical shape and a brazing joint is formed between a brazing material and a sacrificial anode material, and welded tubes in which the end faces of the brazing sheet are butt-welded.

[0112] (Brazing sheet manufacturing method) The brazing sheet can be obtained, for example, by the following manufacturing method: That is, the manufacturing method of the brazing sheet includes an aluminum ingot preparation step of preparing a plurality of aluminum ingots including a core ingot that will become the core material, an intermediate ingot that will become the intermediate material, a brazing filler material ingot that will become the brazing filler material, and a sacrificial anode material ingot that will become the sacrificial anode material; a lamination step of superposing the intermediate material block and the brazing material block on one surface of the core material block and superposing the sacrificial anode material block on the other surface to prepare a clad block; a clad rolling step of hot rolling the clad ingot to integrate a plurality of the aluminum ingots to produce a clad plate; a hot rolling step of hot rolling the clad plate; Next, a cold rolling step of subjecting the clad plate to one or more cold rolling processes; After the cold rolling step is completed, the method includes a final annealing step in which the clad plate is annealed by holding it at a temperature of 180° C. or higher and 350° C. or lower for 1 hour or higher and 10 hours or lower.

[0113] [Aluminum block preparation process] In the aluminum ingot preparation process, multiple aluminum ingots are prepared, including an ingot for core material, an ingot for intermediate material, an ingot for brazing material, and an ingot for sacrificial anode material. The chemical compositions of these aluminum ingots are the same as the chemical compositions of the corresponding layers in the brazing sheet. The method for casting the aluminum ingots is not particularly limited, and known methods such as DC casting and CC casting can be used. The cast aluminum ingots may be subjected to the lamination process as is, or may be subjected to a homogenization treatment as necessary before being subjected to the lamination process.

[0114] The holding temperature and holding time for the homogenization treatment may be appropriately set depending on the chemical composition of the aluminum ingot. For example, when homogenizing a core ingot, it is preferable to hold the core ingot at a temperature of 450°C to 620°C for 1 hour to 20 hours. By performing the homogenization treatment on the core ingot under these conditions, the Mg2Si precipitated during casting can be sufficiently redissolved into the Al matrix. As a result, after the brazing heat treatment of the brazing sheet is completed, the amount of Mg2Si precipitated by aging can be increased, and the increase in the strength of the brazing sheet due to age hardening can be increased.

[0115] Furthermore, the thickness of the aluminum ingot may be adjusted by hot rolling the aluminum ingot after casting, if necessary. When hot rolling the aluminum ingot, it is preferable to hold the aluminum ingot at a temperature of 400°C or higher and 560°C or lower for 1 hour to 10 hours before hot rolling. If the heating temperature before hot rolling is lower than 400°C or the heating time is shorter than 1 hour, the plastic workability of the aluminum ingot may be reduced, and cracks may be more likely to occur at the edges of the aluminum ingot during hot rolling. If the heating temperature before hot rolling exceeds 560°C, the aluminum ingot may melt due to heat generated during processing. If the heating time exceeds 10 hours, productivity may be reduced.

[0116] [Lamination process] In the lamination step, a plurality of aluminum blocks are laminated in the order of the desired brazing sheet layers to produce a clad block.

[0117] [Clad rolling process] In the clad rolling step, the clad ingot is subjected to hot rolling to integrate the plurality of aluminum ingots into a clad plate. The rolling conditions for the clad rolling are not particularly limited as long as they allow adjacent aluminum ingots to be joined together.

[0118] [Hot rolling process] In the hot rolling process, the clad plate obtained by clad rolling is hot rolled to reduce the thickness of the clad plate. In the hot rolling process, the clad plate is preferably heated to 400°C or higher and 560°C or higher before hot rolling. The temperature of the clad plate at the end of hot rolling is preferably 350°C or lower. The thickness of the clad plate after hot rolling is preferably 1 mm or higher and 10 mm or lower. In this case, the processing strain accumulated in the clad plate in the subsequent cold rolling process can be made sufficiently large, making it possible to easily form a fibrous structure in the core material of the brazing sheet.

[0119] [Cold rolling process] In the cold rolling step, the clad plate after the hot rolling step is subjected to cold rolling once or multiple times, thereby obtaining a brazing sheet having a desired thickness.

[0120] [Intermediate annealing process] When multiple cold rollings are performed in the cold rolling process, the manufacturing method may further include an intermediate annealing process in which the clad plate is heated and annealed during the cold rolling. However, from the viewpoint of increasing the processing strain accumulated in the clad plate, it is preferable not to perform the intermediate annealing process.

[0121] [Final annealing process] In the final annealing step, the clad sheet after cold rolling is annealed by holding it at a temperature of 180°C or higher and 350°C or lower for 1 hour or higher and 10 hours or lower. As described above, by annealing the clad sheet in which sufficient processing strain has accumulated in the cold rolling step under the specific heating conditions, a fibrous structure can be formed in the core material of the resulting brazing sheet, and the amount of processing strain remaining in the core material can be made sufficiently large.

[0122] When such a brazing sheet is subjected to brazing heating, the core material recrystallizes using the accumulated processing strain as a driving force, and the crystal grains of the recrystallized core material can be refined. As a result, the strength of the brazing sheet after brazing can be improved. From the viewpoint of more reliably obtaining this effect, the heating temperature in the final annealing step is preferably 180°C or higher and 300°C or lower.

[0123] If the heating temperature in the final annealing step is less than 180°C or the holding time is less than 1 hour, the formability of the brazing sheet may be reduced, making it difficult to form the brazing sheet into the desired shape. Furthermore, if the heating temperature in the final annealing step exceeds 350°C, the core material may recrystallize during annealing, making it impossible to obtain the desired properties. If the holding time in the final annealing step exceeds 10 hours, the productivity of the brazing sheet may be reduced. [Example]

[0124] An embodiment of the brazing sheet and its manufacturing method will be described with reference to Figures 1 to 3. As shown in Figure 1, the brazing sheet 1 of this embodiment has a core material 11, an intermediate material 12 laminated on one surface of the core material 11, a brazing material 13 laminated on the intermediate material 12, and a sacrificial anode material 14 laminated on the other surface of the core material 11.

[0125] The core material 11 is made of an aluminum alloy containing Si: 0.3% to 1.0% by mass, Cu: 0.4% to 1.0% by mass, Mn: 1.0% to 2.0% by mass, and Mg: 0.30% to 0.90% by mass, with the remainder being Al and unavoidable impurities. The metal structure of the core material 11 contains a fibrous structure.

[0126] The intermediate material 12 is made of an aluminum alloy having a pitting potential lower than that of the core material 11. The brazing filler metal 13 is made of an aluminum alloy having a chemical composition containing 11% by mass to 13% by mass of Si, with the balance being Al and unavoidable impurities. The brazing filler metal 13 has a thickness of 18 μm or more. The sacrificial anode material 14 is made of an aluminum alloy having a chemical composition containing 3.0% by mass to 8.0% by mass of Zn and 0% by mass to 0.50% by mass of Mn, with the balance being Al and unavoidable impurities. The sacrificial anode material 14 has a thickness of 20 μm or more.

[0127] The total thickness of the core material 11, intermediate material 12, brazing material 13, and sacrificial anode material 14 is 120 μm or more and 350 μm or less. The thickness of the core material 11 is 55% or more of the total thickness of the core material 11, intermediate material 12, brazing material 13, and sacrificial anode material 14.

[0128] The brazing sheet 1 of this example is suitable for a heat exchanger tube 2 for circulating a refrigerant in an automotive heat exchanger. Fig. 2 shows an example of a tube 2 made of the brazing sheet 1. For convenience, the intermediate material 12 is not shown in Fig. 2.

[0129] The shape of the tube 2 in a cross section perpendicular to the flow direction of the refrigerant is generally rectangular or elliptical. The tube 2 shown in Fig. 2 has an outer wall portion 21 that forms its outer wall, and a partition portion 23 that divides the internal space surrounded by the outer wall portion 21 into two refrigerant flow paths 22. A brazing material 13 of the brazing sheet 1 is disposed on the outer surface of the outer wall portion 21, and a sacrificial anode material 14 of the brazing sheet 1 is disposed on the inner surface. Such a tube 2 can be formed, for example, by bending the brazing sheet 1 and abutting both ends 15 in the width direction of the brazing sheet 1 against the sacrificial anode material 14.

[0130] A more specific example of the configuration of the brazing sheet 1 of this example will be described along with its manufacturing method. To manufacture the brazing sheet 1, first prepare a core material ingot having the chemical compositions shown in Table 1 under alloy symbols A1 to A5, an intermediate material ingot having the chemical compositions shown in alloy symbols B1 to B8, a brazing material ingot having the chemical compositions shown in alloy symbols C1 to C4, and a sacrificial anode material ingot having the chemical compositions shown in alloy symbols D1 to D4. These aluminum ingots can be manufactured by DC casting, for example. In Table 1, the symbol "-" indicates that the content of the element in question is less than 0.01% by mass, and "Bal." indicates the remainder.

[0131] After preparing the aluminum ingots, the surfaces of the aluminum ingots are chamfered. Then, for some of the core ingots, they are heated and homogenized at the heating temperature and holding time shown in Table 2. The intermediate ingots, brazing filler ingots, and core ingots are held at 480°C for one hour and then hot-rolled. The thicknesses of the intermediate ingots, brazing filler ingots, and core ingots are adjusted so that the cladding ratio of the final brazing sheet is the desired value.

[0132] Next, the core material ingot, intermediate material ingot, brazing material ingot, and sacrificial anode material ingot are stacked together in the combinations shown in Table 2 to form a clad ingot. This clad ingot is held at a temperature of 480°C for 1 hour, and then subjected to clad rolling to obtain a clad plate with a thickness of 3.0 mm.

[0133] The obtained clad plate is subjected to cold rolling to make the overall thickness of the clad plate the thickness shown in Table 2. The clad plate is then held at a temperature of 220°C for 2 hours for final annealing. Through the above steps, the brazing sheet 1 (test materials S1 to S11) shown in Table 2 can be obtained. The thicknesses of the core material 11, intermediate material 12, brazing material 13, and sacrificial anode material 14 in test materials S1 to S11 are the values ​​shown in Table 2. Table 2 lists the thickness of the core material 11 as well as the ratio (unit: %) of the thickness of the core material 11 to the overall thickness of the brazing sheet 1.

[0134] Note that test materials S12 to S15 shown in Table 2 are test materials for comparison with test materials S1 to S11. The configurations of test materials S12 to S14 are the same as those of test materials S1 to S11, except that the combination of core material 11, intermediate material 12, brazing material 13, and sacrificial anode material 14 is changed as shown in Table 2.

[0135] Test material S15 can be produced in the same manner as test material S9, except that the holding temperature in the final annealing is changed from 220°C to 400°C and the holding time is changed from 2 hours to 3 hours.

[0136] Next, the methods for evaluating the various properties of the test materials S1 to S15 will be described.

[0137] [Evaluation of the metal structure of the core material before brazing heating] Before brazing heating, the test material is cut along the rolling direction to expose a cross section parallel to both the rolling direction and the thickness direction. This cross section is mirror-polished and then etched using Keller's solution. The metallographic structure of the core material exposed on the cross section is then observed using a metallurgical microscope. In the "Metallic Structure" column of Table 2, the symbol "F" indicates that the metallographic structure of the core material is a fibrous structure, and the symbol "R" indicates that the metallographic structure of the core material is an equiaxed structure resulting from recrystallization.

[0138] [Average grain size of core material after brazing heating] The test material is suspended in a heating furnace and the temperature inside the furnace is increased so that the temperature remains within the range of 577°C to 600°C for 3 minutes. After cooling in the furnace, the test material is removed from the heating furnace and stored in a constant temperature bath at 20°C for 7 days.

[0139] The test material was then removed from the thermostatic chamber and cut along the rolling direction to expose a cross section parallel to both the rolling direction and the thickness direction. This cross section was then mirror-polished, and a crystal orientation map of the core material was obtained using electron backscatter diffraction (EBSD). The observation area for EBSD was set to a length of 1.5 mm in the rolling direction. Furthermore, in EBSD, among the boundaries of regions with different crystal orientations, boundaries where the difference in crystal orientation between adjacent regions is 20 degrees or more are defined as grain boundaries, and the regions surrounded by grain boundaries are defined as crystal grains.

[0140] The circle equivalent diameters of all crystal grains in the crystal orientation map obtained by EBSD were calculated, and these were then arithmetically averaged to calculate the average crystal grain size of the core material. The average crystal grain size of the core material for each test material after brazing is shown in Table 3. Note that the symbol "-" in the "Average crystal grain size of the core material after brazing heating" column in Table 3 indicates that the average crystal grain size of the core material was not evaluated.

[0141] [Tensile strength after brazing heat] The test material is suspended in a heating furnace and the temperature inside the furnace is increased so that the temperature remains within the range of 577°C to 600°C for 3 minutes. After cooling in the furnace, the test material is removed from the heating furnace and stored in a constant temperature bath at 20°C for 7 days.

[0142] Using this test material, a tensile test is conducted using a method in accordance with JIS Z2241:2011. The tensile speed in the tensile test is 10 mm / min, and the gauge length is 50 mm. The tensile strength of the test material is determined based on the stress-strain curve obtained from the tensile test. The tensile strength of each test material after brazing is shown in Table 3. Note that the symbol "-" in the "Tensile strength after brazing heat" column in Table 3 indicates that the tensile strength after brazing was not evaluated.

[0143] [Brazability] Brazeability was evaluated using a mini-core specimen 3 simulating the core of a corrugated fin heat exchanger. As shown in FIG. 3, the mini-core specimen 3 has a corrugated fin 31 and two flat plates 32 (32a, 32b) that sandwich the corrugated fin 31. The corrugated fin 31 is a 0.08 mm thick plate made of an aluminum alloy in which 1.5 mass % of Zn is added to an A3003 alloy. The corrugated fin 31 is tempered according to the tempering code H14. The length of the corrugated fin 31 is 40 mm, the height is 10 mm, and the pitch between adjacent apexes 311 is 3 mm.

[0144] The flat plate 32 is made of one of the test materials and has a length of 40 mm and a width of 16 mm.

[0145] To prepare the mini-core specimen 3, first, a corrugated fin 31 is placed on the brazing filler metal 13 of one flat plate 32a. Next, the other flat plate 32b is placed on the corrugated fin 31 so that the corrugated fin 31 and the brazing filler metal 13 are in contact with each other. After that, a fluoride flux solution with a concentration of 5% by mass is applied to the brazing filler metal 13 of the flat plate 32 using a brush. Note that the intermediate material 12 is omitted from FIG. 3 for the sake of convenience.

[0146] The mini-core test piece 3 thus obtained is placed in a heating furnace, and then the temperature inside the furnace is increased and the mini-core test piece 3 is heated so that the temperature inside the furnace is kept within the range of 577°C to 600°C for 3 minutes. In this way, the flat plate 32 made of the test material and the corrugated fin 31 are brazed together.

[0147] The brazeability is evaluated based on the bonding rate of the corrugated fins 31 and whether or not the corrugated fins 31 melt. To calculate the bonding rate of the corrugated fins 31, first, the corrugated fins 31 are cut out from the mini-core specimens 3 after brazing. Next, the ratio of the number of brazed connections between the tops 311 of the corrugated fins 31 and the flat plates 32 formed after brazing to the total number of contact points between the tops 311 of the corrugated fins 31 and the flat plates 32 before brazing is calculated. This value, expressed as a percentage (unit: %), is defined as the bonding rate of the corrugated fins 31. The bonding rates of the corrugated fins 31 for the mini-core specimens 3 using each test material are shown in the "Bonding Rate" column of Table 3. Note that the symbol "-" in this column indicates that brazeability was not evaluated.

[0148] To evaluate whether the corrugated fins 31 have melted, the mini-core specimens 3 after brazing are visually observed to determine whether the corrugated fins 31 have melted. The "Melted fins" column in Table 3 shows whether the corrugated fins 31 have melted in the mini-core specimens 3 using each test material.

[0149] [Corrosion resistance of brazing filler metal] To evaluate the brazing filler metal side corrosion resistance, the mini-core specimen 3 described above is first prepared. After coating the sacrificial anode material 14 of the flat plate 32 of the mini-core specimen 3 with insulating resin, the surface of the brazing filler metal 13 side is used as the test surface, and a CASS test is performed according to the method specified in JIS H8502:1999. The test time for the CASS test is 1000 hours. In the "Brazing Filler Metal Side Corrosion Resistance" column of Table 3, the symbol "A+" indicates that the test material does not undergo corrosion penetration until the test is completed, the symbol "A" indicates that corrosion penetration occurs in the test material after 700 hours have elapsed since the start of the test, the symbol "B" indicates that corrosion penetration occurs in the test material before 700 hours have elapsed since the start of the test, and the symbol "-" indicates that the CASS test was not performed.

[0150] [Corrosion resistance of sacrificial anode material] To evaluate the corrosion resistance of the sacrificial anode material side, two test materials are placed in a heating furnace with the sacrificial anode materials 14 abutting against each other, and the temperature inside the furnace is then increased. The two test materials are then heated so that the temperature inside the furnace remains within the range of 577°C to 600°C for three minutes. After the two test materials have cooled in the furnace, they are removed from the heating furnace and one test material is separated from the other. The brazing filler metal 13 of the test material is then coated with insulating resin.

[0151] The test piece thus obtained is used to carry out a cyclic immersion test. In the cyclic immersion test, the surface of the test piece on the side of the sacrificial anode material 14 is immersed in a solution of 500 mass ppm of Cl. - and 100 ppm by mass of SO4 2- and 10 mass ppm of Cu 2+ The test piece is immersed in an 88°C aqueous solution containing ammonium nitrate for 8 hours, then removed from the solution and left to stand at room temperature for 16 hours. This cycle is repeated. The test is terminated when 1000 hours have elapsed since the start of the test. The corrosion resistance is then evaluated based on the time it takes for penetration of the test material due to corrosion.

[0152] The symbol "A" in the "Corrosion resistance of sacrificial anode material side" column in Table 3 indicates that the test material was not penetrated by corrosion until the test was completed, the symbol "B" indicates that the test material was penetrated by corrosion before the test was completed, and the symbol "-" indicates that the test was not performed.

[0153] [Table 1]

[0154] [Table 2]

[0155] [Table 3]

[0156] As shown in Tables 2 and 3, the core material, intermediate material, brazing filler metal, and sacrificial anode material in test materials S1 to S11 have the specific chemical compositions and metal structures, as well as the specific thicknesses. Therefore, these test materials are excellent in all aspects: strength after brazing, brazing ability, brazing filler metal-side corrosion resistance, and sacrificial anode material-side corrosion resistance. Among these test materials, test materials S2, S3, S8, and S10, which contain Zn in the intermediate material, have even higher brazing filler metal-side corrosion resistance than the other test materials due to the high sacrificial corrosion protection effect of the intermediate material.

[0157] On the other hand, the intermediate materials of test materials S12 and S13 contain a relatively large amount of Cu, and therefore have a lower sacrificial corrosion protection effect on the core material than the intermediate materials of test materials S1 to S11. Therefore, test materials S12 and S13 have inferior corrosion resistance on the brazing filler metal side compared to test materials S1 to S11.

[0158] The Si content in the brazing filler metal of test material S14 is lower than the specific range, and therefore test material S14 is inferior in brazeability to test materials S1 to S11.

[0159] In the case of test material S15, the heating temperature in the final annealing process was too high, so the core material recrystallized in the final annealing process and became an equiaxed structure. When brazing is performed using a brazing sheet whose core material has an equiaxed metal structure, the crystal grains become coarse after brazing heating compared to when the core material has a fibrous metal structure. Therefore, test material S15 has inferior strength after brazing compared to test materials S1 to S11.

[0160] The above describes examples of the brazing sheet and its manufacturing method, but the specific aspects of the brazing sheet and its manufacturing method according to the present invention are not limited to the above-mentioned examples, and the configuration can be changed as appropriate within the scope that does not detract from the spirit of the present invention. [Explanation of symbols]

[0161] 1. Brazing sheet 11 Heartwood 12 Intermediate materials 13 Brazing material 14 Sacrificial anode material

Claims

1. a core material having a chemical composition containing Si: 0.3 mass% or more and 1.0 mass% or less, Cu: 0.4 mass% or more and 1.0 mass% or less, Mn: 1.3 mass% or more and 2.0 mass% or less, and Mg: 0.30 mass% or more and 0.90 mass% or less, with the balance being Al and unavoidable impurities, and having a fibrous structure in its metal structure; an intermediate material made of an aluminum alloy having a chemical composition containing Si: 0.3% by mass or more and 1.0% by mass or less, Mn: 1.3% by mass or more and 2.0% by mass or less, with the balance being Al and unavoidable impurities, and having a pitting potential lower than that of the core material, and laminated on one surface of the core material; a brazing filler metal having a chemical composition containing Si: 11 mass% or more and 13 mass% or less, with the balance being Al and unavoidable impurities, and having a thickness of 18 μm or more, laminated on the intermediate material; a sacrificial anode material having a chemical composition containing Zn: 3.0% by mass or more and 8.0% by mass or less, Mn: 0% by mass or more and 0.40% by mass or less, with the balance being Al and unavoidable impurities, and having a thickness of 20 μm or more, laminated on the other surface of the core material; The total thickness of the core material, the intermediate material, the brazing material, and the sacrificial anode material is 120 μm or more and 350 μm or less, A brazing sheet, wherein the thickness of the core material is 55% or more of the total thickness of the core material, the intermediate material, the brazing material, and the sacrificial anode material.

2. The brazing sheet according to claim 1, wherein the core material further contains one or more elements selected from the group consisting of Fe: 0.05 mass% or more and 1.0 mass% or less, Ti: 0.05 mass% or more and 0.30 mass% or less, Cr: 0.05 mass% or more and 0.30 mass% or less, V: 0.05 mass% or more and 0.30 mass% or less, and Zr: 0.05 mass% or more and 0.30 mass% or less.

3. 3. The brazing sheet according to claim 1, wherein the sacrificial anode material further contains one or more elements selected from the group consisting of Si: more than 0% by mass and 1.0% by mass or less, Fe: 0.05% by mass or more and 1.0% by mass or less, Ti: 0.05% by mass or more and 0.30% by mass or less, Cr: 0.05% by mass or more and 0.30% by mass or less, V: 0.05% by mass or more and 0.30% by mass or less, Zr: 0.05% by mass or more and 0.30% by mass or less, In: more than 0.10% by mass or less, Sn: more than 0.10% by mass or less, and Ni: 0.05% by mass or more and 2.0% by mass or less.

4. The brazing sheet according to any one of claims 1 to 3, wherein the brazing filler metal further contains one or more elements selected from the group consisting of Fe: 0.05% by mass or more and 1.0% by mass or less, Zn: more than 0% by mass and 4.0% by mass or less, Ti: 0.05% by mass or more and 0.30% by mass or less, Cr: 0.05% by mass or more and 0.30% by mass or less, V: 0.05% by mass or more and 0.30% by mass or less, Zr: 0.05% by mass or more and 0.30% by mass or less, In: more than 0.10% by mass or less and Sn: more than 0.10% by mass or less, Na: 0.001% by mass or more and 0.050% by mass or less, and Sr: 0.001% by mass or more and 0.050% by mass or less.

5. 5. The brazing sheet according to claim 1, wherein the aluminum alloy constituting the intermediate material further contains one or more elements selected from the group consisting of Zn: more than 0% by mass and 3.0% by mass or less, Fe: 0.05% by mass or more and 1.0% by mass or less, Ti: 0.05% by mass or more and 0.30% by mass or less, Cr: 0.05% by mass or more and 0.30% by mass or less, V: 0.05% by mass or more and 0.30% by mass or less, Zr: 0.05% by mass or more and 0.30% by mass or less, In: more than 0.10% by mass or less, Sn: more than 0.10% by mass or less, and Ni: 0.05% by mass or more and 2.0% by mass or less, and has a thickness of 12 μm or more.

6. A core material having a chemical composition containing Si: 0.3% by mass or more and 1.0% by mass or less, Cu: 0.4% by mass or more and 1.0% by mass or less, Mn: 1.0% by mass or more and 2.0% by mass or less, and Mg: 0.30% by mass or more and 0.90% by mass or less, with the remainder consisting of Al and unavoidable impurities, and having a fibrous structure in the metal structure; an intermediate material made of an aluminum alloy having a chemical composition containing Si: 0.3% by mass or more and 1.0% by mass or less, Mn: 1.0% by mass or more and 2.0% by mass or less, with the balance being Al and unavoidable impurities, and having a pitting potential lower than that of the core material, and laminated on one surface of the core material; a brazing filler metal having a chemical composition containing Si: 11 mass% or more and 13 mass% or less, with the balance being Al and unavoidable impurities, and having a thickness of 18 μm or more, laminated on the intermediate material; a sacrificial anode material having a chemical composition containing Zn: 3.0 mass% or more and 8.0 mass% or less, Mn: 0 mass% or more and Mn: 0 mass% or more and 0.50 mass% or less, with the balance being Al and unavoidable impurities, and having a thickness of 20 μm or more, laminated on the other surface of the core material; The total thickness of the core material, the intermediate material, the brazing material, and the sacrificial anode material is 120 μm or more and 350 μm or less, A method for manufacturing a brazing sheet, wherein the thickness of the core material is 55% or more of the total thickness of the core material, the intermediate material, the brazing material, and the sacrificial anode material, an aluminum ingot preparation step of preparing a plurality of aluminum ingots including a core ingot that will become the core material, an intermediate ingot that will become the intermediate material, a brazing material ingot that will become the brazing material, and a sacrificial anode material ingot that will become the sacrificial anode material; a lamination step of superposing the intermediate material block and the brazing material block on one surface of the core material block and superposing the sacrificial anode material block on the other surface to prepare a clad block; a clad rolling step of hot rolling the clad ingot to integrate a plurality of the aluminum ingots to produce a clad plate; a hot rolling step of hot rolling the clad plate; Next, a cold rolling step of subjecting the clad plate to one or more cold rolling processes; A method for manufacturing a brazing sheet, comprising: a final annealing step in which, after the cold rolling step is completed, the clad plate is annealed by holding it at a temperature of 180°C or higher and 350°C or lower for 1 hour or higher and 10 hours or lower.

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