JP4993440B2 - High strength aluminum alloy clad material for heat exchangers with excellent brazeability - Google Patents

Description

  In the case of manufacturing an aluminum heat exchanger such as a radiator or a heater core by brazing using a fluoride flux or a flux containing a cesium compound in an inert gas atmosphere, this invention is a tube material (cladding material) that is a structural member of the heat exchanger. The present invention relates to a high-strength aluminum alloy clad material for heat exchangers that is excellent in brazing properties (including those that are bent and formed into a tube shape by welding or brazing).

  Tube materials such as radiators and heater cores for automobiles are made of an Al-Mn alloy such as JIS A3003 as a core material, clad with a brazing material of an Al-Si alloy on one side, and in some cases, Al-- A three-layer clad material having a thickness of about 0.3 mm in which a sacrificial anode material made of a Zn-based alloy or an Al-Zn-Mg-based alloy is clad is used.

  The brazing material of Al-Si alloy is for joining tubes and fins, and joining tubes and header plates. Brazing is performed using an inert gas atmosphere using a fluoride flux or a flux containing a cesium compound. It is performed by brazing or vacuum brazing. In addition, the sacrificial anode material on the inner surface of the tube material comes into contact with the working fluid during use and exhibits a sacrificial anode effect to prevent pitting corrosion and crevice corrosion of the core material. The sacrificial anode material on the outer surface of the tube material is sacrificed during use. Demonstrate pitting corrosion of core material by demonstrating anode effect.

  Conventionally, radiators and heater cores have been manufactured by bending and welding a brazing material on one side of a core material and a clad plate with a sacrificial anode material on the other side. Although it was performed by brazing (welding type), as shown in FIGS. 1 and 2, in recent years, a clad plate material in which a brazing material 4 is clad on one side of a core material 3 and a sacrificial anode material 5 is clad on the other side is bent. The tube shape 1 or 2 is formed without being welded only by processing, and a method of being manufactured by assembling to the header plate and integrally brazing (brazing die) is performed.

  In recent years, with the demand for reducing the weight of automobiles, automotive heat exchangers are also required to reduce the thickness of structural materials, including tube materials, from the viewpoint of energy and resource savings. In order to increase the strength of the tube material, a large amount of Mn, Cu, Si, etc. is added to the core material, and the corrosion resistance of the core material is lowered due to the inclusion of these elements, so a large amount of Zn is added to the sacrificial anode material. Has been proposed (see Patent Document 1).

In addition, a large amount of Mg is added to the sacrificial anode material to cause fine precipitation of Mg ₂ Si at the interface between the sacrificial anode material and the core material, or a small amount of Mg is added to the core material to finely precipitate Mg ₂ Si in the core material. In addition, a material structure having higher strength has been proposed (see Patent Document 2). However, when Mg is added to the sacrificial anode material, it is effective with respect to the welding type tube material, but with respect to the brazing type tube material shown in FIGS. There is a problem that Mg reacts with the flux to form a compound such as MgF ₂ and the function of the flux is impaired, resulting in a brazing defect. When Mg is added to the core material, Mg diffuses from the core material to the brazing material. Similarly, Mg reacts with the flux to form a compound such as MgF ₂ , thereby reducing the function of the flux and causing a brazing defect. For this reason, the amount of Mg added is limited to 0.2% or less, and in the case of a brazed tube material, there is a limit to increasing the strength by adding Mg.

Therefore, as shown in FIGS. 1 and 2, in order to increase the strength of the brazed tube material having a surface where the sacrificial anode material and the solder are directly joined, a large amount of Mn, Cu, Si, etc. is added to the core material. A method of adding Mn, Fe, and Si to the sacrificial anode material has also been proposed (see Patent Document 3). In this case, Mn and Fe react with Si of the brazing material that has diffused on the surface of the sacrificial anode material. However, since a large number of Al-Mn-Si and Al-Fe-Si intermetallic compounds are formed, the addition of these elements reduces the brazing wettability of the sacrificial anode material surface, resulting in brazing defects. There is a problem.
Japanese Patent Laid-Open No. 11-293371 Japanese Patent Application Laid-Open No. 08-283891 JP 2003-293064 A

  In order to obtain a brazing property that the brazing-type radiator tube material achieves higher strength than the above-described conventional tube material, and improves the brazing wettability of the sacrificial anode material surface. As a result of testing and investigating the relationship between the strength and brazeability of the clad material, the composition of the core material and sacrificial anode material in the clad material and their combination, and the structure of the core material and sacrificial anode material, the following was found. .

  Addition of Cu, Si and Mn is effective to increase the strength of the core material. However, if a large amount of Cu and Si is added, the melting point of the core material decreases, and part of the core material melts during brazing heating. There's a problem. This is because a large amount of Si in the brazing material diffuses into the core material during brazing heating, and the core material in the vicinity of the boundary between the brazing material and the core material melts locally. Therefore, the amount of Si and Cu added to the core material Must be restricted.

  As for the sacrificial anode material, it is effective to contain elements such as Mn, Fe, Si, etc. in order to increase the strength of the tube material. The wettability decreases and the brazing property is impaired. Even if the strength of the tube material is improved by increasing the strength of the sacrificial anode surface, the sacrificial anode material disappears due to preferential corrosion during use of the heat exchanger. It does not contribute to the improvement of strength durability during use of the vessel, and the strength durability is drastically lowered during use.

  If Si is added to the sacrificial anode material and the amount of Si added to the sacrificial anode material exceeds the Si concentration of the core material, Si diffuses from the sacrificial anode material to the core material during brazing heating. The Al-Mn-Si compound is finely precipitated near the boundary between the sacrificial anode material and the core material, and the strength of the tube material is improved. In this case, even if the sacrificial anode material disappears, the strength is increased on the core material side. Therefore, the strength durability during use of the heat exchanger is less decreased, and the strength durability is improved as compared with the case where Mn, Fe, and Si are added to the sacrificial anode material.

  However, when a large amount of Si is added to the sacrificial anode material, a large amount of Si diffuses from the brazing material so that the core material near the boundary between the brazing material and the core material melts. Because the core material melts locally, the amount of Si added to the sacrificial anode material must also be limited. When Mn, Fe, and Si are added to the sacrificial anode material, Si in the sacrificial anode material forms an Al—Mn—Si-based or Al—Fe—Si-based compound. The amount of Si diffusing from the sacrificial anode material into the core material is small, and there is almost no effect of increasing the strength of the core material.

  The present invention has been made on the basis of the above findings, and the object thereof is to provide excellent strength and durability and brazing, and is suitably used as a tube material for heat exchangers, particularly automotive heat exchangers. An object of the present invention is to provide an aluminum alloy clad material for a heat exchanger.

The high-strength aluminum alloy clad material for heat exchanger excellent in brazing performance according to claim 1 for achieving the above object is an aluminum alloy clad material obtained by clad a sacrificial anode material on at least one surface of a core material. The core material is Si: 0.7 to 1.2% (mass%, the same applies hereinafter) , Cu: more than 0.2% and 1.0% or less, Mn: 1.0 to 1.8%, Ti: 0 The sacrificial anode material is composed of an aluminum alloy containing 0.05 to 0.35%, the balance being Al and inevitable impurities, and Si: 1.0 to 1.5%, Zn: 1.0 to 7.0% It is characterized in that it is made of an aluminum alloy composed of the balance Al and inevitable impurities, and the Si content of the sacrificial anode material is not less than the Si content of the core material.

  A high-strength aluminum alloy clad material for a heat exchanger excellent in brazeability according to claim 2 is characterized in that the sacrificial anode material is clad on one surface of the core material and the Al-Si brazing material on the other surface. Is clad.

  The high strength aluminum alloy clad material for heat exchangers excellent in brazing property according to claim 3 is characterized in that, in claim 1, sacrificial anode materials are clad on both surfaces of the core material.

  The high-strength aluminum alloy clad material for a heat exchanger excellent in brazing property according to claim 4 is any one of claims 1 to 3, wherein the core material is further Cr: 0.02-0.3%, Zr: 0 It contains one or two of 0.02 to 0.3%.

  The high-strength aluminum alloy clad material for a heat exchanger excellent in brazing property according to claim 5 is any one of claims 1 to 4, wherein the core material is further V: 0.01 to 0.3%, B: 0. It is characterized by containing 1 type or 2 types among 0.01-0.3%.

The high-strength aluminum alloy clad material for heat exchangers excellent in brazing property according to claim 6 is characterized in that in any one of claims 1 to 5, the sacrificial anode material is further In: 0.05% or less, Sn: 0.00. It is characterized by containing one or two of 05 % or less.

  The high-strength aluminum alloy clad material for a heat exchanger excellent in brazeability according to claim 7 has a temperature increase rate of up to 400 ° C at 50 ° C / min in any one of claims 1 to 6, and reaches up to 595 ° C. In the case where the heating is performed under the condition that the time is within 30 minutes, the average crystal grain size on the surface of the sacrificial anode material is 0.13 mm or less.

  ADVANTAGE OF THE INVENTION According to this invention, the aluminum alloy clad material for heat exchangers which has the outstanding intensity | strength durability and brazing property and can be used suitably as a tube material of a heat exchanger, especially an automotive heat exchanger is provided. .

The significance of the alloy components in the high strength aluminum alloy clad material for heat exchangers with excellent brazing properties according to the present invention and the reasons for their limitation will be described.
(Heartwood)
Si: Si has a function of improving the strength of the core material by solid solution hardening and fine precipitation hardening of an Al—Mn—Si based compound. The preferable content range is 0.3 to 1.2%, and if it is less than 0.3%, the effect is not sufficient. If it exceeds 1.2%, the corrosion resistance is lowered and the melting point of the core material is lowered. Local melting tends to occur during application. The more preferable content range of Si is 0.7 to 1.2%.

  Cu: Cu functions to improve the anticorrosion effect by improving the strength of the core material, making the potential of the core material noble, and increasing the potential difference from the sacrificial anode material. Furthermore, Cu in the core material diffuses into the sacrificial anode material during brazing heating and forms a gentle concentration gradient. As a result, the potential on the core material side becomes noble and the potential on the surface side of the sacrificial anode material becomes base and sacrificed. A gentle potential distribution is formed in the anode material, and the corrosion form is changed to the full corrosion type. The preferable content of Cu is in the range of 0.2 to 1.0%. When the content is less than 0.2%, the effect is small, and when the content exceeds 1.0%, the melting point of the core material is lowered, so that it is localized during brazing. Easy melting occurs. The more preferable content range of Cu is 0.4 to 0.7%.

  Mn: Mn functions to improve the corrosion resistance by improving the strength of the core material and making the potential of the core material noble and increasing the potential difference from the sacrificial anode material. A preferable content range is 1.0% to 1.8%, and if the content is less than 1.0%, the effect is small. If the content exceeds 1.8%, a coarse compound is generated at the time of casting, and the rollability is low. As a result of harm, it is difficult to obtain a healthy plate. A more preferable content range of Mn is 1.2 to 1.7%.

Ti: Ti is divided into a high-concentration region and a low region in the thickness direction of the core material, and the layers are alternately distributed. Corrosion occurs by preferentially corroding the low-Ti concentration region over the high-concentration region. It has the effect of layering the form, thereby preventing the progress of corrosion in the thickness direction and improving the pitting corrosion resistance of the material. The preferable content of Ti is in the range of 0.05 to 0.35%. If it is less than 0.05%, this effect is small, and if it exceeds 0.35%, casting becomes difficult, and workability deteriorates and is healthy. Production of the material becomes difficult. A more preferable content range of Ti is 0.1 to 0.2 % .

  Cr and Zr: Cr and Zr increase the recrystallization temperature during brazing heating, coarsen the grain size of the core material, suppress the grain boundary diffusion of Si in the brazing material, and suppress erosion. , Function to improve brazing. The preferable content ranges of Cr and Zr are 0.02 to 0.3%, respectively, and even if the content exceeds 0.3%, the effect is saturated. The more preferable content ranges of Cr and Zr are each 0.05 to 0.2%.

  V and B: V and B coarsen the grain size of the core material and suppress Mg grain boundary diffusion during brazing heating. A preferable content range is 0.01 to 0.3%, respectively, and even if it exceeds 0.3%, the effect is saturated.

(Sacrificial anode material)
Si: Si improves the strength of the sacrificial anode material. Furthermore, it diffuses into the core material during brazing heating, and fine precipitation of an Al—Si—Mn compound is generated in the core material, thereby improving the strength of the core material. The preferable content range is 1.0 to 1.5%, and if the content is less than 1.0%, the effect is small. If the content exceeds 1.5%, the amount of diffusion to the core material during brazing heating is large. Therefore, local melting is likely to occur in the core material. The more preferable content range of Si is 1.1 to 1.4%.

Zn: Zn lowers the potential of the sacrificial anode material and maintains the sacrificial anode effect on the core material. As a result, pitting corrosion and crevice corrosion of the core material are prevented. The preferable range of Zn is 1.0 to 7.0%. When the content is less than 1.0%, the effect is small, and when the content exceeds 7.0%, the self-corrosion property of the sacrificial anode material increases. A more preferable content range of Zn is 2.0 to 5.0 % .

  In, Sn: In and Sn lower the potential of the sacrificial anode material by adding a small amount, ensure the sacrificial anode effect on the core material, and prevent pitting corrosion and crevice corrosion of the core material. The preferable ranges of In and Sn are 0.05% or less (not including 0%), respectively. If the content exceeds 0.05%, the self-corrosion property of the sacrificial anode material increases. More preferable content ranges of In and Sn are 0.01 to 0.03%, respectively.

(Brazing material)
Si: An Al—Si based alloy is used as the brazing material, and an alloy containing 7 to 13% Si is usually used. If the content is less than 7%, the fluidity tends to decrease and does not act effectively, and if it exceeds 13%, it is difficult to produce a sound material. In order to ensure brazing of the material containing Mg in the core material, the Si content range is preferably 9.5 to 12.0%. If the Si content is less than 9.5%, the amount of brazing material may be insufficient. If the Si content exceeds 12.0%, coarse crystallized products of Si are generated in the brazing material, resulting in non-uniform melting of the brazing. A flaw is likely to occur.

  In the brazing material, Fe: 0.15 to 2.0%, Zn: 0.5 to 5.0%, In: 0.05% or less, Sn: 0.05% or less, Cu: 0. Even if it is contained in the range of 5 to 5.0%, Sr: 0.005 to 0.1%, Na: 1 to 100 ppm, Sb: 0.001 to 0.5%, the effect of the present invention is impaired. There is no.

  The aluminum alloy clad material according to the present invention has the above composition and is sacrificed when heated under the condition that the rate of temperature increase to 400 ° C. is 50 ° C./min and the time to reach 595 ° C. is within 30 minutes. The crystal grain size of the surface of the anode material is 0.13 mm or less (130 μm or less). In the above heating conditions, that is, brazing heating, the sacrificial anode material surface has a crystal grain size of 0.13 mm or less, so that wetting and spreading of the sacrificial anode material surface is improved and improved. Easy to get.

  When the wax spreads to the surface of the sacrificial anode material, the grain boundary preferentially becomes a path for spreading the wax, and then the wax spreads wet from the grain boundary in the grain direction. Therefore, when the crystal grain size is small, the number of wet spreading paths increases, and the wax spreads uniformly. On the other hand, when the crystal grain size is large, there are few paths for spreading the wetting, the wetting spread of the wax becomes non-uniform, and the wettability decreases. The crystal grain size of the sacrificial anode material having good wettability on the surface of the sacrificial anode material of brazing is in the range of 0.13 mm or less as viewed from the surface of the sacrificial anode material, and when it exceeds 0.13 mm, the wettability spreads.

  The aluminum alloy clad material according to the present invention ingots a core material alloy, a sacrificial anode material alloy and a brazing material alloy by continuous casting. For example, among the obtained ingots, the core material alloy and the sacrificial anode material alloy Is subjected to a homogenization treatment, and hot rolled the sacrificial anode material alloy and brazing material alloy to a predetermined thickness, and these are combined with the ingot of the core material alloy and hot rolled to obtain a clad material. .

  Thereafter, the clad material is cold-rolled, intermediate-annealed, and cold-rolled to obtain an aluminum alloy clad material having a predetermined thickness. In this case, the degree of cold rolling after intermediate annealing is desirably 20% or more in order to refine the average grain size of the sacrificial anode material after brazing heating to 0.13 mm or less.

  Examples of the present invention will be described below in comparison with comparative examples to demonstrate the effects. These examples show one embodiment of the present invention, and the present invention is not limited thereto.

Example An alloy for a core material having a composition shown in Table 1, an alloy for a sacrificial anode material having a composition shown in Table 2, and an alloy for a brazing material having a composition shown in Table 3 were obtained by ingot casting. Among the ingots, the alloy for the core material and the alloy for the sacrificial anode material are homogenized, and the alloy for the sacrificial anode material and the alloy for the brazing material are hot-rolled to a predetermined thickness. Were combined and hot rolled to obtain a clad material.

  Subsequently, the clad material was cold-rolled, intermediate-annealed, and cold-rolled to obtain an aluminum alloy clad material (H14) having a thickness of 0.20 mm. The structure of the clad was 0.040 mm for the sacrificial anode material, 0.030 mm for the brazing material, and the remaining core material. The intermediate annealing temperature was 350 ° C. and the holding time was 3 hours. The degree of cold rolling work after intermediate annealing was 30%.

  Using the obtained aluminum alloy clad material as a test material, the following method was used to observe the presence or absence of local melting after brazing heating, to measure the average crystal grain size of the sacrificial anode material surface after brazing heating, and to the sacrificial anode material The wettability of the surface wax was evaluated. Moreover, the strength characteristic (tensile strength) after brazing heating was evaluated. The results are shown in Tables 4-5.

  Observation of the presence or absence of local melting: A fluoride flux was applied only to the brazing filler metal surface of the clad material and heated in nitrogen gas at 595 ° C. (material temperature) for 3 minutes. The temperature was raised under the conditions that the time required to reach 50 ° C./min and 595 ° C. (material temperature) was within 30 minutes. About the test material after heating, resin-filled and polished according to a conventional method, and after etching a cross section in a direction perpendicular to the rolling direction with Keller's solution, using an optical microscope, local melting is possible at a magnification of 400 (○) No (× ) Was observed.

Measurement of average grain size of sacrificial anode material: A fluoride flux was applied only to the brazing material surface of the clad plate material, and heated in nitrogen gas at 595 ° C. (material temperature) for 3 minutes. The heating is performed under heating conditions in which the time to reach 50 ° C./min and 595 ° C. (material temperature) is within 30 minutes. 1000-2400) and polished to a mirror surface by buffing. Furthermore, electrolysis was performed at a voltage of 25 to 30 V for 45 to 60 seconds in a mixed solution of 500 ml of pure water, 27 ml (46%) of hydrofluoric acid, and 11 g of boric acid. Thereafter, the polarization microstructure on the surface of the sacrificial anode material was photographed using an optical microscope, and the crystal grain size was measured by a comparative method. For comparison, the standard grain size structure chart of ASTM (E112-61) was used, and the grain size shown in the standard grain size structure chart was used as an index of the average grain size.

  Evaluation of brazing wettability on the surface of the sacrificial anode material: Using the obtained aluminum alloy clad material, a 20 mm × 60 mm plate was cut out, and the end surfaces (all four surfaces) were cut by shaper processing to obtain a size of 15 mm × 55 mm Finished. This plate was placed horizontally in the furnace with the sacrificial anode material face up without applying flux, and heated in nitrogen gas at 595 ° C. (material temperature) for 3 minutes. A photograph of the sacrificial anode material surface after heating taken at a magnification of 16 using an optical microscope (negative-positive reversal photography) (FIG. 3) The average value L of the wax circumference from the top (for example, L = (L1 + L2 in FIG. 3) ) / 2) was measured. In the evaluation of the wetting and spreading property of the wax, the average value L of the wax circumference length was evaluated as good (◯) when the average value L was 1.5 mm or more, and as poor (×) when less than 1.5 mm.

Evaluation of strength characteristics (tensile strength): 3 g / m ² of fluoride-based flux was applied only to the brazing filler metal surface of the obtained aluminum alloy clad material, and then heated in nitrogen gas at 595 ° C. (material temperature) for 3 minutes. Thereafter, a tensile test (based on JIS Z2241) was performed.

As can be seen in Tables 4-5, the test material No. 1-13 , no. 15-24, no. In any of Nos. 26 to 39, local melting during brazing heating was not observed, and the brazing wettability of the sacrificial anode material surface was excellent, and it was confirmed that the brazing heating had sufficient strength.

Comparative Example 1
A core alloy having the composition shown in Table 6 and a sacrificial anode material alloy having the composition shown in Table 7 are ingoted by continuous casting, and then homogenized, and the sacrificial anode material alloy is hot-rolled to a predetermined value. The ingot of the core material alloy, the sacrificial anode alloy B1 hot rolled to a predetermined thickness after ingot formation in Example 1, and the sacrificial anode alloy and core material alloy A1 ingot in Example 1. In combination with the ingot, the alloy C1 for brazing material that was hot rolled to a predetermined thickness after ingot forming in Example 1 was combined and hot rolled to obtain a clad material. Also, the ingot of the core material alloy A1 ingoted in Example 1, the sacrificial anode alloy B1 ingot hot rolled to a predetermined thickness after ingotging in Example 1, and hot rolled to the predetermined thickness after ingot in Example 1. The clad material was obtained by combining with the brazing material alloy C1 and hot rolling.

  Subsequently, the clad material was cold-rolled, intermediate-annealed, and cold-rolled to obtain an aluminum alloy clad material (H14) (test materials No. 101 to 105) having a thickness of 0.20 mm. The structure of the clad was 0.040 mm for the sacrificial anode material, 0.030 mm for the brazing material, and the remaining core material. The intermediate annealing temperature was 350 ° C. and the holding time was 3 hours. The degree of cold rolling work after intermediate annealing was 30%. The test material No. For No. 105, the degree of cold rolling after intermediate annealing was 15%.

  Using the obtained aluminum alloy clad material as a test material, by the same method as in Example 1, observe the presence or absence of local melting after brazing heating, measure the average grain size of the sacrificial anode material surface after brazing heating, The wettability of the sacrificial anode material surface was evaluated. Moreover, the strength characteristic (tensile strength) after brazing heating was evaluated. The results are shown in Table 8.

  As shown in Table 8, the test material No. Since 101 and 102 had a large amount of Cu in the core material and a large amount of Si in the core material, local melting and severe erosion occurred at the boundary between the core material and the brazing material. Test material No. Since 103 had a large amount of Si in the sacrificial anode material, local melting occurred near the boundary between the sacrificial anode material and the core material. Test material No. Since 104 had a small amount of Si in the sacrificial anode material, sufficient strength could not be obtained. Test material No. In No. 105, since the degree of work after ingot annealing was low, the average crystal grain size of the sacrificial anode material surface after brazing heating was coarsened, and the wetting spreadability of the sacrificial anode material surface was reduced.

It is sectional drawing which shows the Example of a brazing-type tube shape. It is sectional drawing which shows the other Example of the brazing-type tube shape. It is a figure which shows the circumference | surroundings length in the wax wettability evaluation of the sacrificial anode material surface.

Explanation of symbols

1 Tube shape 2 Tube shape 3 Core material 4 Brazing material 5 Sacrificial anode material

Claims (7)

An aluminum alloy clad material obtained by cladding a sacrificial anode material on at least one surface of a core material, wherein the core material is Si: 0.7 to 1.2% (mass%, the same applies hereinafter), Cu: 0.2% And 1.0% or less, Mn: 1.0 to 1.8%, Ti: 0.05 to 0.35%, the balance being composed of an aluminum alloy composed of Al and unavoidable impurities, Si: 1.0 to 1.5%, Zn: 1.0 to 7.0%, the balance being composed of an aluminum alloy composed of Al and inevitable impurities, the Si content of the sacrificial anode material is Si of the core material A high-strength aluminum alloy clad material for heat exchangers with excellent brazing characteristics characterized by being at least the content. 2. A high strength brazing heat exchanger according to claim 1, wherein a sacrificial anode material is clad on one surface of the core material and an Al-Si brazing material is clad on the other surface. Aluminum alloy clad material. The high-strength aluminum alloy clad material for heat exchangers with excellent brazeability according to claim 1, wherein a sacrificial anode material is clad on both surfaces of the core material. The core material further contains one or two of Cr: 0.02 to 0.3% and Zr: 0.02 to 0.3%. High-strength aluminum alloy clad material for heat exchangers with excellent brazeability described in 1. The core material further contains one or two of V: 0.01 to 0.3% and B: 0.01 to 0.3%. High-strength aluminum alloy clad material for heat exchangers with excellent brazeability described in 1. The wax according to any one of claims 1 to 5, wherein the sacrificial anode material further contains one or two of In: 0.05% or less and Sn: 0.05 % or less. High strength aluminum alloy clad material for heat exchangers with excellent adhesion. When heating is performed under the condition that the temperature rising rate up to 400 ° C. is 50 ° C./min and the time required to reach 595 ° C. is 30 minutes or less, the average grain size of the sacrificial anode material surface is 0.13 mm or less. The high-strength aluminum alloy clad material for heat exchangers having excellent brazing properties according to any one of claims 1 to 6.

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