JP5084490B2 - Aluminum alloy clad material - Google Patents

Description

  The present invention relates to an aluminum alloy clad material used for a heat exchanger or the like, for example, a clad material assembled as an aluminum heat exchanger by brazing in an inert gas atmosphere using a fluoride flux. The aluminum alloy clad material according to the present invention is suitably used for aluminum heat exchangers such as automotive evaporators and condensers, and has excellent corrosion resistance.

  Aluminum heat exchangers are used as heat exchangers for automobile oil coolers, intercoolers, heaters, car air conditioner evaporators, condensers, or oil coolers for hydraulic equipment and industrial machinery. An aluminum heat exchanger usually forms an aluminum alloy brazing sheet coated with a brazing material, laminates it to form a fluid passage, and arranges corrugated aluminum alloy fins between the fluid passages, These are manufactured by brazing and integrating them.

  For example, in a Delon cup evaporator, a tube sheet is formed by press-molding an aluminum alloy brazing sheet material clad with a brazing material on both sides. Next, corrugated aluminum alloy fins are laminated between the tube sheets, and these are brazed to join the core plate and the fins and to form a coolant passage between the tube sheets.

  As a tube sheet, an aluminum alloy containing Mn such as an Al—Mn alloy, an Al—Mn—Cu alloy, an Al—Mn—Cu—Mg alloy, an Al—Mn—Mg alloy, such as JIS 3003 alloy, 3005 alloy, etc. Al-Si alloy, Al-Si-Mg alloy, Al-Si-Mg-Bi alloy, Al-Si-Bi alloy, Al-Si-Be alloy on one or both sides of the core material An aluminum alloy brazing sheet clad with a brazing material made of an Al—Si—Bi—Be alloy is used. As the fin material, an Al—Mn alloy, an Al—Mn—Mg alloy, an Al—Mn—Cu alloy, an Al—Mn—Zn alloy, or the like is used. As the brazing method, a vacuum brazing method or a brazing method using a chloride flux or a fluoride flux is used.

  In order to improve the corrosion resistance of the tube sheet from the outside (outside air), a fin material having a lower potential than the tube sheet, such as an Al-Mn-Zn alloy, an Al-Mn-Sn alloy fin material, Corrosion protection of the tube sheet which is a fluid passage constituent material is achieved by the sacrificial anticorrosion effect of the fin material. However, there is a problem that corrosion occurs in a range where the sacrificial anticorrosive effect of the fin material does not reach, for example, a general portion of the tank portion or a brazed portion.

Patent Documents 1 and 2 describe a clad material in which the potential of the core material is adjusted by adding Zn to the brazing material in order to improve the corrosion resistance of the outer brazing material in order to solve the above problem.
JP-A-7-88678 JP-A-11-199957

  By adding Zn to such an outer brazing material, the corrosion resistance of the flat part of the tank part can be improved. However, in the tank mating portion which is a brazing portion, there remains a problem that preferential corrosion occurs and a through leakage occurs.

  In view of the above problems, an object of the present invention is to provide an aluminum alloy clad material that prevents preferential corrosion at a brazed portion and that does not cause through pitting corrosion at an early stage.

  The inventors of the present invention have made the Zn concentration on the sacrificial brazing material side and the Cu concentration on the core material side at the interface between the outer brazing material (hereinafter referred to as “sacrificial brazing material”) and the core material at the stage of the clad material before brazing. The present invention has been completed by obtaining effective knowledge regarding prevention of preferential corrosion at the brazed portion.

  The present invention is characterized in that, in claim 1, Si 0.07 to 0.40% (mass%, the same shall apply hereinafter), Fe 0.1 to 0.4%, Cu 0.3 to 1.0%, Mn 0.4 to 1.5% , Containing 0.05 to 0.20% Ti, the core material manufactured from an ingot consisting of the balance Al and unavoidable impurities, and clad on one or both sides of the core material, Zn 0.5 to 4.0% An aluminum alloy cladding material comprising a sacrificial brazing material made of an ingot comprising Si 7.0 to 12.5%, Fe 0.05 to 0.25%, and the balance Al and inevitable impurities, At the stage of the clad material before brazing, the sacrificial brazing material side Zn concentration (ZnC) and the core material side Cu concentration (CuC) at the interface between the sacrificial brazing material and the core material are 0.9 ≦ ZnC / CuC ≦ 7. It was characterized as an aluminum alloy clad material.

  Further, in claim 2, the core material further contains V 0.02 to 0.10%. Further, in claim 3, the sacrificial brazing material contains at least one of Sn 0.05 to 0.20% and In 0.05% to 0.20%.

  ADVANTAGE OF THE INVENTION According to this invention, the aluminum alloy clad material which showed favorable corrosion resistance in the tank part in which the corrosion prevention effect by a sacrificial corrosion fin does not work, and prevented the preferential corrosion of the brazing filler fillet part can be provided.

A. Relationship between Zn concentration and Cu concentration at the clad material stage before brazing The inventors examined the relationship between Zn concentration and Cu concentration at the interface between the sacrificial brazing material and the core material at the clad material stage before brazing. did. The brazing sheet which changed variously Zn content of a sacrificial brazing material and Cu content of a core material was produced, and it shape | molded in the cup 1 shown in FIG. These cups were stacked in three stages as shown in FIG. 2, and test pieces simulating the tank part of the heat exchanger tube were prepared and subjected to a corrosion test to evaluate the preferential corrosion of the brazed part. As a result, the following findings have been found. In FIG. 2, the plurality of cups 1 are stacked so that the tank matching portions 2 of adjacent cups are in contact with each other, and the adjacent cups 1 are not in contact with each other in the tank flat portion 3.

A-1. For Zn, FIG. 3 shows the tank mating section (clad stage before brazing) of FIG. That is, the distribution of the Zn concentration (ZnC) and the Cu concentration (CuC) of the sacrificial brazing material 4 and the core material 5 in the clad material used for the adjacent cup is schematically shown. In the clad material before brazing shown in FIG. 3, the sacrificial brazing material 4 has a high concentration of ZnC and the core material 5 has a low concentration of CuC. When brazing is performed using such a clad material, as shown in FIG. 4, the Zn concentration (ZnW) of the final solidified portion 61 in the brazed portion 6 is such that the primary crystal portion 62 and the core material of the brazed portion 5. Since the concentration is higher than ZnW of 5, the potential of the final solidified portion 61 becomes lower than the surroundings. In this case, in the clad material before brazing, the relationship between ZnC and CuC is ZnC / CuC> 7. As a result, when such a clad material is exposed to a corrosive environment after brazing, preferential corrosion of the brazed portion 6 occurs due to preferential corrosion of the final solidified portion 61.

A-2. For Cu, FIG. 5 also shows the tank mating section (cladding stage before brazing) of FIG. That is, the distribution of ZnC and CuC in the sacrificial brazing material 4 and the core material 5 in the clad material used for the adjacent cup is schematically shown. The clad material before brazing shown in FIG. 5 has a low concentration of ZnC in the sacrificial brazing material 4 and a high concentration of CuC in the core material. When brazing is performed using such a clad material, a low concentration region of Cu concentration (CuW) is formed at the interface between the brazing portion 6 and the core material 5, as shown in FIG. The potential at becomes lower than the surroundings. In this case, in the clad material before brazing, the relationship between CuC and ZnC is ZnC / CuC <0.9. As a result, when such a clad material is exposed to a corrosive environment after brazing, preferential corrosion of the brazed portion 6 occurs due to preferential corrosion of the CuW low concentration region.

A-3. Relationship between ZnC and CuC As described above, the present inventors clarified the requirements of the brazing sheet for preventing preferential corrosion of the brazed portion based on the relationship between ZnC and CuC. That is, an aluminum alloy cladding in which 0.9 ≦ ZnC / CuC ≦ 7 in relation to ZnC on the sacrificial brazing material side and CuC on the core material side at the interface between the sacrificial brazing material and the core material at the stage of the clad material before brazing It was found that the preferential corrosion of the brazed portion can be effectively prevented in the material.

B. The content of each constituent element constituting the aluminum alloy clad material in the ingot stage will be described below with respect to the component content in the ingot stage of each constituent element constituting the aluminum alloy clad material according to the present invention.

B-1. Sacrificial brazing material Zn: Zn is dissolved in an aluminum alloy, and the corrosion resistance of the tube is improved by preventing the core material from corroding the natural electrode potential of the sacrificial brazing material. However, when there is too much Zn content, it will concentrate in the brazing part of a tank and the preferential corrosion of a brazing part will generate | occur | produce. If the Zn content is less than 0.5 mass% (hereinafter simply referred to as “%”), the sacrificial corrosion effect of the sacrificial brazing material cannot be exhibited, and if it exceeds 4.0%, preferential corrosion of the brazed portion is promoted. Therefore, Zn content is prescribed | regulated to 0.5 to 4.0%. The Zn content is preferably 0.5 to 2.5%.

  When Si: Si is added to an aluminum alloy, the melting point of the aluminum alloy decreases. The brazing temperature in manufacturing the heat exchanger is usually around 600 ° C., and the sacrificial brazing material needs to be melted around that temperature. When the Si content is less than 7.0%, the melting point is not sufficiently lowered, the sacrificial brazing material is not sufficiently melted, and brazing is not sufficiently achieved. On the other hand, if the Si content exceeds 12.5%, a large crystallized product is generated during casting, and the core material may be melted during brazing using this crystallized product as a base point. Therefore, the Si content is defined as 7.0 to 12.5%.

  When Fe: Fe is added to the aluminum alloy, it is dissolved in aluminum or an Al—Fe-based compound is formed, which contributes to improving the strength. In addition, this Al—Fe compound is a starting point for pitting corrosion in a neutral environment. If the Fe content exceeds 0.25%, the corrosion resistance in a neutral environment becomes remarkable and the deterioration proceeds. On the other hand, if the Fe content is less than 0.05%, the strength is insufficient. Therefore, the Fe content is specified to be 0.05 to 0.25%.

  When Sn, In: Sn or In is added to the aluminum alloy, the sacrificial corrosion effect of the sacrificial brazing material is further enhanced by solid solution in aluminum and lowering the potential. If the content is less than 0.05%, the contribution of the sacrificial corrosion effect is not sufficient, and if it exceeds 0.2%, rolling workability is also hindered. Therefore, the Sn or In content is preferably 0.05 to 0.2%. Sn and In may be added singly or both. When both are added, the total content of both is preferably 0.05 to 0.2%.

B-2. When the core material Si: Si is added to the aluminum alloy, it forms a solid solution in the matrix and forms an intermetallic compound with Fe and Mn, thereby contributing to an improvement in strength. If the Si content is less than 0.07%, the effect of improving the strength is insufficient, and if it exceeds 0.4%, the meltability and external corrosion resistance of the core material during brazing are inferior. Accordingly, the Si content is specified to be 0.07 to 0.4%.

  When Fe: Fe is added to the aluminum alloy, it forms a solid solution and forms an intermetallic compound with Si and Mn in the matrix, thereby contributing to an improvement in strength. If the Fe content is less than 0.1%, the effect of improving the strength is insufficient, and if it exceeds 0.4%, the corrosion resistance of the core material deteriorates when the core material is a composite material. Therefore, the Fe content is specified to be 0.1 to 0.4%.

  Cu: When Cu is added to an aluminum alloy, it dissolves in the matrix and contributes to strength improvement. If the Cu content is less than 0.3%, the strength improving effect is poor. On the other hand, if the Cu content exceeds 1.0%, the meltability of the core material is inferior during brazing, and intergranular corrosion occurs in the core material during brazing, resulting in poor external corrosion resistance. Therefore, the Cu content is specified to be 0.3 to 1.0%.

  Mn: When Mn is added to an aluminum alloy, it forms a solid solution and forms an intermetallic compound with Si and Fe in the matrix, thereby contributing to strength improvement. If the Mn content is less than 0.4%, the strength improvement effect is insufficient. On the other hand, if the Mn content exceeds 1.5%, when the composite material is used as a core material, cracking occurs at the end during rolling, making rolling difficult. Therefore, the Mn content is specified to be 0.4 to 1.5.

  Ti: Ti forms a compound of Ti at the time of casting and forms a light and dark part around it. This light and shade part is stretched by rolling, and a light and dark layer of Ti is formed in the rolling direction. Such a Ti light / dark layer improves the corrosion resistance of the core material itself. When the Ti content is less than 0.05%, the effect of improving the corrosion resistance by the Ti concentration layer is insufficient. On the other hand, if the Ti content is 0.20% or more, a giant Ti crystallized product is formed and causes cracking during rolling. Therefore, the Ti content is specified to be 0.05 to 0.20%.

  V: When V is added to an aluminum alloy, it forms a solid solution or an Al-V compound in aluminum and forms a dark and light layer of V around it. This dark and light layer is stretched by rolling to form a dark and dark layer of V in the plate thickness direction, further contributing to the improvement of corrosion resistance along with the addition of Ti. When the V content is less than 0.02%, the effect of improving the corrosion resistance by the light and dark layer is insufficient. On the other hand, if the V content exceeds 0.1%, the corrosion resistance is poor. Therefore, the V content is preferably 0.02 to 0.10%.

C. Production of clad material The aluminum alloy clad material according to the present invention has a structure in which the sacrificial brazing material is clad on both sides of the core material and one is an outer brazing material and the other is an inner brazing material, or one surface of the core material. Alternatively, the sacrificial brazing material may be clad to form an outer brazing material, and the other surface may be clad with BA4343P, BA4045P, and BA4047P defined by JIS to form an inner brazing material. Such a configuration can be variously selected depending on the shape of the heat exchanger and the heating conditions when producing the heat exchanger.

C-1. Casting process The core material, outer brazing material and inner brazing material are first cast into an ingot having a thickness of 600 to 700 mm, a length of 4000 to 5000 mm, and a width of 1000 to 1200 mm by ordinary semi-continuous casting. Here, the outer brazing filler metal and the inner brazing filler metal are rolled at a hot rolling start temperature of 460 to 510 ° C. so as to have a predetermined cladding ratio.

C-2. The outer brazing filler metal and the inner brazing filler metal that have been hot-rolled in the cladding process are superimposed on the core material so as to have a predetermined cladding ratio. The superposed product is hot-rolled at a start temperature of 460 ° C. and an end temperature of 470 ° C. In the clad hot rolling of the aluminum alloy clad material according to the present invention, the temperature is preferably set to 450 to 470 ° C. from the start to the end. This is by hot rolling in this temperature range to suppress the diffusion of Zn in the brazing material and Cu in the core material due to preheating during hot rolling and temperature rise during rolling, and during brazing heating This is to reduce the amount of diffusion of these components.

  In particular, in hot rolling in a temperature range exceeding 500 ° C., the temperature increase of the outer brazing material surface due to rolling is higher than that of the core material. Therefore, the amount of Zn diffusion from the outer brazing material to the core material is larger than the amount of Cu diffusion from the core material to the outer brazing material, and the amount of Zn at the interface between the outer brazing material and the core material is reduced. As a result, the ratio (ZnC / CuC) of the Zn concentration on the brazing material side and the Cu concentration on the core material side at the interface between the brazing material and the core material at the stage of the clad material before brazing becomes small.

  What was hot-rolled has a final plate thickness of 0.20 to 0.40 mm by cold rolling, and is further subjected to final annealing at a temperature of 360 to 400 ° C. for 10 seconds to 8 hours to obtain a clad material (brazing sheet). Produced. Here, as a method of annealing, either batch annealing or continuous annealing treatment is appropriately used.

  Hereinafter, preferred embodiments of the present invention will be described in detail based on examples and comparative examples.

Examples 1-28 and Comparative Examples 1-27
Table 1 shows the alloy components of the outer brazing material which is a sacrificial brazing material of the aluminum alloy clad material of the present invention. A to N are within the scope of the present invention, and OT is outside the scope of the present invention. In addition, BA4045P alloy and BA4343P alloy were used for the inner brazing material.

  Table 2 shows alloy components of the core material of the aluminum alloy clad material according to the present invention. 1-9 are within the scope of the present invention and 10-19 are outside the scope of the present invention.

  The core material, the outer brazing material and the inner brazing material were cast in a size of ingot size width 600 mm, length 5000 mm, width 1200 mm. The outer brazing material and the inner brazing material were rolled at a hot rolling start temperature of 500 ° C. so as to have a predetermined cladding ratio, and then superposed on the core material so as to have a predetermined cladding ratio. Next, the clad hot rolling was performed at a start temperature of 460 ° C. and an end temperature of 470 ° C., and the final plate thickness was 0.3 mm by cold rolling, and the final annealing was performed at 360 ° C. for 2 hours. An aluminum alloy clad material (brazing sheet) was prepared.

  Table 3 shows combinations of the outer brazing material, the core material, and the inner brazing material of each of the examples and the comparative examples. In Comparative Examples 24-27, the alloy ingot components of the core material and the brazing filler metal are within the scope of the present invention, but the start temperature of the clad hot rolling is set to 520 ° C., the end temperature is set to 530 ° C., and then cold. A final annealing temperature of 360 ° C. was performed for 2 hours at 0.3 mm by rolling.

  The following evaluation was performed on the aluminum brazing sheet shown in Table 3.

(1) The ratio of the Zn concentration (ZnC) on the sacrificial brazing material side and the Cu concentration (CuC) on the core material side at the interface between the sacrificial brazing material and the core material at the stage of the clad material before brazing. After collecting and polishing the cross section, the position of the cross section was analyzed using EPMA (electron beam analysis analyzer) at n = 5, and ZnC and CuC were measured at five locations, respectively, to obtain the arithmetic average value of (ZnC / CuC). . The results are shown in Table 3. Table 3 shows (Zn content / Cu content) in the ingot stage.

(2) Tensile test The brazing sheet having the structure shown in Table 3 was processed into a JIS No. 5 test piece, and heated corresponding to brazing (600 ° C for 3 minutes) in a nitrogen atmosphere. These samples were subjected to a tensile test to measure the strength. A tensile strength of 140 kg / cm ² or higher was accepted and less than that was rejected. The results are shown in Table 3.

(3) External corrosion resistance test A brazing sheet having the structure shown in Table 3 was molded into a cup shown in FIG. 6, a hole having a diameter of 12 mm was formed in the center, and stacked in three stages as shown in FIG. A 5% aqueous solution was applied, and brazing heating (3 minutes at 600 ° C.) was performed in a nitrogen atmosphere. Next, the hole was masked with a silicon sealant manufactured by Shin-Etsu Chemical, and a test piece was produced. Then, after conducting a SWAAT test according to ASTM G85 for 500 hours, the test piece was washed with water and the corrosion product was removed with nitric acid / chromic acid chromic acid. The pitting depth was measured at. At that time, the presence or absence of penetration of the tank fitting portion was confirmed. The pitting corrosion depth of less than 70 μm was accepted and more than that was rejected. Moreover, the thing which the tank matching part has not penetrated was made into the pass, and the thing which has penetrated was made unsuccessful.

  As is apparent from Table 3, Examples 1 to 28 showed high strength even after brazing. Further, in Examples 1 to 28, the pitting corrosion depth of the tank flat portion was less than 70 μm, so that no through pitting corrosion occurred, and no through corrosion occurred in the tank matching portion.

  In Comparative Examples 1 to 4, the components of the sacrificial outer brazing material and the core material were each within the scope of the present invention, and no penetration corrosion occurred in the flat portion of the tank. However, at the stage of the clad material before brazing, the relationship between the brazing material side Zn concentration and the core material side Cu concentration at the interface between the sacrificial brazing material and the core material was ZnC / CuC> 7. As a result, the Zn concentration in the final solidified part of the brazed part is higher than that of the primary crystal part and the core material of the brazed part. occured.

  In Comparative Example 5, the components of the sacrificial brazing material and the core material are within the scope of the present invention. However, at the stage of the clad material before brazing, the relationship between the Zn concentration on the sacrificial brazing material side and the Cu concentration on the core material side at the interface between the sacrificial brazing material and the core material was Zn / Cu <0.9. As a result, no penetration corrosion occurred in the flat part of the tank, but a low-concentration region of Cu was formed at the interface between the brazing part and the core material, and the low-concentration region of Cu was preferentially corroded to the tank mating part. Through corrosion occurred.

  In Comparative Examples 6 and 7, the core component is within the scope of the present invention, but the sacrificial brazing component departs from the scope of the present invention. Therefore, at the stage of the clad material before brazing, the relationship between the Zn concentration on the sacrificial brazing material side and the Cu concentration on the core material side at the interface between the sacrificial brazing material and the core material was Zn / Cu <0.9. As a result, no penetration corrosion occurred in the flat part of the tank, but a low-concentration region of Cu was formed at the interface between the brazing part and the core material, and the low-concentration region of Cu was preferentially corroded to the tank mating part. Penetration corrosion occurred and the corrosion of the flat part also progressed.

  In Comparative Example 8, because the amount of Si in the brazing material was insufficient, a problem occurred during brazing, and a sample for corrosion test could not be produced. In Comparative Example 9, since the amount of Si in the brazing material was too large, it melted at the time of cladding, and a sample for measuring the tensile strength could not be produced.

  In Comparative Example 10, the core material component is in the present invention example. However, the sacrificial brazing material component departs from the present invention, and the sacrificial brazing material is sacrificed at the interface between the sacrificial brazing material and the core material at the stage of the clad material before brazing. The relationship between the Zn concentration on the brazing material side and the Cu concentration on the core material side was ZnC / CuC <0.9. As a result, the corrosion resistance of the flat part of the tank was also inferior, and a low concentration region of Cu was formed at the interface between the brazing part and the core material, and the low concentration region of Cu was preferentially corroded to cause penetration corrosion in the tank mating part. .

  In Comparative Example 11, the core component was in the inventive example, but the sacrificial brazing component departed from the present invention. Although penetration corrosion did not occur in the flat part of the tank, the relationship between the Zn concentration on the brazing material side and the Cu concentration on the core material side at the interface between the sacrificial brazing material and the core material is ZnC / CuC> 7. As a result, the Zn concentration in the final solidified part of the brazed part is higher than that of the primary crystal part and the core material of the brazed part. occured. In Comparative Example 12, the tensile strength was insufficient because the Fe content of the outer brazing material was too small.

  In Comparative Example 13, the core component is within the scope of the present invention, and the relationship between the Zn concentration on the brazing material side and the Cu concentration on the core material side at the interface between the sacrificial brazing material and the core material at the stage of the clad material before brazing. Satisfies 0.9 ≦ Zn / Cu ≦ 7. However, the components of the sacrificial brazing material deviated from the present invention, and as a result, penetration corrosion did not occur in the tank mating portion, but penetration corrosion occurred in the tank flat portion where the Fe content of the sacrificial brazing material was excessive. It was.

  In Comparative Example 14, at the stage of the clad material before brazing, 0.9 ≦ Zn / Cu ≦ 7 was satisfied, and the corrosion resistance of the tank flat portion and the tank fitting portion was good, but the Si amount of the core material was It was less than the present invention, and the tensile strength was insufficient.

  In Comparative Example 15, the relationship between the Zn concentration on the sacrificial brazing material side and the Cu concentration on the core material side at the interface between the sacrificial brazing material and the core material at the stage of the clad material before brazing. 0.9 ≦ Zn / Cu ≦ 7 was satisfied, and the corrosion resistance of the tank mating portion was good, but the tank flat portion penetrated because the Si content of the core material deviated from the present invention.

In Comparative Example 16, the relationship between the Zn concentration on the sacrificial brazing material side and the Cu concentration on the core material side at the interface between the sacrificial brazing material and the core material. 0.9 ≦ Zn / Cu ≦ 7 was satisfied, and the corrosion resistance of the tank mating portion and the flat portion of the tank were good, but the tensile strength was insufficient because the Fe content of the core material was insufficient.
In Comparative Example 17, the relationship between the Zn concentration on the sacrificial brazing material side and the Cu concentration on the core material side at the interface between the sacrificial brazing material and the core material. 0.9 ≦ Zn / Cu ≦ 7 was satisfied, and the corrosion resistance of the tank mating portion was good. However, since the Fe content of the core material was excessive, penetration corrosion occurred in the flat portion of the tank.
In Comparative Example 18, the component of the sacrificial brazing material is within the range of the present invention, but the component of the core material deviates from the present invention. There was no penetration corrosion in the flat part of the tank, but the relationship between the Zn concentration on the brazing filler metal side and the Cu concentration on the core material side at the interface between the sacrificial brazing material and the core material at the stage of the clad material before brazing is Zn / Cu > 7. As a result, the Zn concentration in the final solidified part of the brazed part is higher than that of the primary crystal part and the core material of the brazed part. occured. Moreover, since the Cu content of the core material was insufficient, the tensile strength was insufficient.

In Comparative Example 19, since the Cu content of the core material was too large, it melted at the time of cladding, and a sample for measurement of tensile strength could not be produced.
In Comparative Example 20, there is a relationship between the Zn concentration on the sacrificial brazing material side and the Cu concentration on the core material side at the interface between the sacrificial brazing material and the core material. 0.9 ≦ Zn / Cu ≦ 7 was satisfied, and the corrosion resistance of the tank mating portion and the flat portion of the tank were good, but the tensile strength was insufficient because the Mn content of the core material was insufficient.
In Comparative Example 21, rolling was not possible because the Mn content of the core was too high.
In Comparative Example 23, rolling was not possible because the Ti content in the core was too high.

  In Comparative Example 22, the component of the sacrificial brazing material was within the range of the present invention, but the component of the core material deviated from the present invention, so that penetration corrosion occurred in the tank flat portion.

  In Comparative Examples 24-27, since the temperature of the clad hot rolling was too high, the relationship between the Zn concentration on the brazing material side and the Cu concentration on the core material side at the interface between the sacrificial brazing material and the core material at the stage of the clad material before brazing. Zn / Cu <0.9. As a result, penetration corrosion did not occur in the tank flat part, but penetration corrosion occurred in the tank fitting part.

  Thus, the present invention exhibits high brazing strength and good corrosion resistance without causing penetration corrosion in the tank general part and the joint part. For example, an aluminum alloy clad material having excellent external corrosion resistance can be provided as a brazing sheet for an automotive heat exchanger.

FIG. 1 is a front view showing a cup molded using an aluminum alloy clad material according to the present invention. FIG. 2 is a front view showing a test piece simulating the tank portion of the heat exchanger tube by stacking the cups shown in FIG. 1 in three stages. FIG. 3 schematically shows the distribution of the Zn concentration and the Cu concentration at the tank matching portion at the stage of the clad material before brazing. FIG. 4 shows a state after brazing of the clad material shown in FIG. FIG. 5 schematically shows the distribution of Zn concentration and Cu concentration at the tank matching portion in the stage of the clad material before brazing. FIG. 6 shows a state after brazing of the clad material shown in FIG.

Explanation of symbols

1 ............ Cup 2 ...... ...... Tank matching part 3 ...... ...... Tank flat part 4 ...... Sacrificial brazing material 5 ...... ...... Core material 6 ...... ...... Brazed part 61 ...... Final solidification part 62 ...... Primary crystal part CuC, CuW ... Cu concentration ZnC, ZnW ... Zn concentration

Claims (3)

  Si 0.07 to 0.40% (mass%, the same applies hereinafter), Fe 0.1 to 0.4%, Cu 0.3 to 1.0%, Mn 0.4 to 1.5%, Ti 0.05 to 0.20 %, And is clad on one side or both sides of the core material made of an ingot comprising the balance Al and unavoidable impurities, Zn 0.5 to 4.0%, Si 7.0 to 12.5 And a sacrificial brazing material manufactured from an ingot consisting of the balance Al and inevitable impurities, and a stage of the clad material before brazing. An aluminum alloy clad material characterized in that the sacrificial brazing material side Zn concentration (ZnC) and the core material side Cu concentration (CuC) at the interface between the sacrificial brazing material and the core material satisfy 0.9 ≦ ZnC / CuC ≦ 7 .   The aluminum alloy clad material according to claim 1, wherein the core material further contains V 0.02 to 0.10%.   The aluminum alloy clad material according to claim 1 or 2, wherein the sacrificial brazing material contains at least one of Sn 0.05 to 0.20% and In 0.05% to 0.20%.

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