JP2009275246A - Brazing sheet for heat exchanger made of aluminum alloy, heat exchanger made of aluminum alloy, and method for producing heat exchanger made of aluminum alloy - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a brazing sheet for a heat exchanger made of an aluminum alloy, which attains the optimum balance of a Zn content in a general part and a header/tank joint, and prevents the preferential corrosion in the general part and the header/tank joint with an inexpensive and rational structure, so as to prevent the early generation of piercing pitting in each part. <P>SOLUTION: As a result of examining a Zn diffusion profile in the joint J, by controlling the Zn content X (wt.%) of an Al-Zn-based lining material to 0.5 to 1.0, and controlling a product XY in the case thickness Y (μm) is 30 to 70, to 25 to 70, in the lining material 4b at the header/tank 6 joint, the concentration of Zn is not made surplus in the boundary B with a brazing filler metal 6c, and the optimum balance of the Zn content in the general part G and the joint J of the lining material as a whole is attained, and thus the initial piercing pitting can be prevented in both of the general part G and the joint J. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an Al alloy heat exchanger in which the corrosion resistance of a joint portion that forms a hollow structure is improved using a molded brazing sheet.

Al alloy heat exchangers are used for heat exchangers such as automobile radiators, heaters, car air conditioner evaporators, condensers, and the like.
Such a conventional Al alloy heat exchanger, for example, a radiator for an automobile, is shown in FIGS. 1 (a) and 1 (b). Fig.1 (a) is a front view of the heat exchanger 1 for motor vehicles, FIG.1 (b) is the AA cross-section enlarged schematic diagram of Fig.1 (a).

  The heat exchanger 1 is a hollow fluid passage through which cooling water passes, and is formed by sandwiching corrugated fins 3 between tubes 2 formed by molding an aluminum alloy brazing sheet coated with a brazing material. The core 5 is manufactured by integrating the header plates 4A and 4B molded and punched at both ends of the tube 2 by brazing. Further, resin or aluminum alloy tanks 6A and 6B are joined via header plates 4A and 4B to form a heat exchanger medium passage 7 having a hollow structure, and cooling water is introduced into the tube 2.

The tank 6 and the header plate 4 are made of an Al—Mn alloy, an aluminum alloy containing Mn, for example, a brazing material made of an Al—Si alloy on one side of a core material 6a, 4a made of a JIS3003 alloy or the like. An aluminum alloy brazing sheet clad with an Al—Zn alloy, for example, a JIS7072 alloy, is used on the other side which is clad and is in contact with cooling water.
As a brazing method, a brazing method using a fluoride flux is performed.

  Between the tank 6 and the header plate 4, an aluminum alloy brazing sheet (hereinafter referred to as “tank material”) 6 of an aluminum alloy brazing sheet constituting the tank 6 and an aluminum alloy brazing sheet constituting the header plate 4. A lining material 4b made of an Al—Zn alloy (hereinafter referred to as “header material”) 4 is joined through a joint portion (hereinafter referred to as “header / tank joint portion”) J.

  In the brazing process when assembling the heat exchanger 1, the Al—Si alloy of the brazing material 6c is melted and joined, and the Al—Zn alloy of the lining material 4b is not melted, and Zn is heated by heating in the brazing process. It diffuses in the direction of the core material 4a. Further, the lining material 4 b in the general part G of the header material 4 at that time is arranged so as to face the inside of the tank 6. Therefore, Zn in the lining material 4b of the general part G of the header material 4 not only diffuses toward the core material 4a during brazing, but also desorbs toward the space inside the tank 6 and stays in a sealed space. Part is also taken back into the lining material 4b. As a result, the remaining amount of Zn in the general portion G after brazing is larger than that in the joint portion J.

Moreover, since the temperature during brazing is relatively low in the space inside the tank 6, the degree of Zn diffusion is relatively small in the lining material 4b in the general part G of the header material 4 facing the tank 6, Compared with the joint J between the tank 6 and the header plate 4, the amount of Zn after brazing increases.
The increase in the amount of Zn after brazing in the general part G is functionally effective in that it is necessary to prevent through-holes from being formed early in the lining material 4b of the general part G. It is a phenomenon.

On the other hand, with respect to the header material 4 at the joint J, since the lining material 4b is in contact with the brazing material 6c of the tank material 6, Zn is only diffused toward the core material 4a. The remaining amount of is reduced.
FIG. 2 shows a Zn diffusion profile at the junction J between the tank 6 and the header plate 4.
As shown in the figure, in the lining material 4b of the header / tank junction, Zn is dispersed from the boundary B with the brazing material 6c in the direction of the core material 4a, and the concentration is highest at the boundary B, and in the direction of the core material 4a. The Zn distribution becomes lower in concentration. This is because the diffusion energy is large on the core material 4a side where the Zn concentration is low and low on the boundary B side. As a result, the Zn concentration decreases toward the core material 4a direction so as to draw an exponential function curve approximated by an oblique straight line in the figure. It is because it is not converted.

As a result of showing such a non-uniform Zn diffusion profile, the Zn concentration is not sufficiently reduced at the Al—Zn alloy layer of the lining material 4b of the header / tank junction after heating by brazing, particularly at the boundary B thereof. Due to this, it is more likely to be corroded particularly in a salt water environment as compared with the Al—Si alloy layer of the brazing material 6c.
For example, when a conventional brazing sheet as shown in Patent Document 2 is used, an Al-Zn alloy layer of the lining material 4b at the header / tank junction as shown in the photograph of the junction J cross section in FIG. However, there was a problem that it corroded preferentially and penetrated early.

Therefore, as described above, with respect to the header material 4 in the joint portion J, although there is a tendency that the remaining amount of Zn after brazing tends to decrease, the Zn concentration does not decrease toward the core material 4a. As a result of the uniform Zn diffusion profile, the Zn concentration is high at the boundary B, which preferentially corrodes and causes early penetration.
In order to prevent this, when the Zn amount of the entire lining material 4b of the header material 4 is reduced, the anticorrosion function of the lining material 4b of the general part G is impaired, and a through-hole is formed in the general part G at an early stage. Cause.

  Therefore, as a means for preventing such corrosion of the joint J between the Al—Zn alloy and the brazing material, as disclosed in Patent Document 3 as an aluminum alloy laminated heat exchanger, an Al—Zn alloy layer and an Al It is also possible to consider adopting a method of preventing the preferential corrosion of the brazed portion with the anticorrosive effect of the Al—Zn alloy layer by inserting a brazing sheet between the −Zn alloy layers.

However, since the brazing sheet is used as the joining member, there is a problem that the number of parts increases and the cost increases.
In addition, it is necessary to change the material of the tank material to a double-sided clad material of Al-Zn, and if the tank material is changed to a double-sided clad material, it will be necessary to perform the joining of the tank and the pipe material, etc. There is a problem that costs increase due to an increase in the number of parts and man-hours.
Japanese Patent Laid-Open No. 6-23535 JP-A-53-138955 JP-A-6-170519

  The above problems in the prior art are how to achieve an optimal balance of the Zn content of the entire lining material 4b that does not cause through pitting corrosion at each part of the general part G and the joint J of the header material 4. This results in a problem.

  In view of the above problems in the prior art, the present invention can achieve an optimum balance of the Zn amount in the general part and the header / tank joint, and has a low-cost and rational structure to preferential corrosion of the general part and the header / tank joint. It is an object of the present invention to provide a brazing sheet for an aluminum alloy heat exchanger, an aluminum alloy heat exchanger, and a method for manufacturing an aluminum alloy heat exchanger capable of preventing the occurrence of through pitting corrosion at each part. And

The inventor produced brazing sheets in which the amount of Zn and the cladding ratio of the header-lining material were variously changed, produced test pieces simulating the header / tank joint, and conducted a corrosion test. Accordingly, the preferential corrosion of the lining material of the header / tank joint was evaluated, and studies were carried out to clarify the optimum balance of Zn content as a brazing sheet for preventing preferential corrosion. As a result, the brazing sheet for an aluminum alloy heat exchanger in which the product of the Zn content (wt%) and the cladding thickness (μm) of the header lining material is 25 to 70 at the level of the cladding material before brazing, It became clear that the optimal balance of Zn content of the brazing sheet for heat exchangers can be realized.

  The brazing sheet for an aluminum alloy heat exchanger of the present invention was clad by hot rolling on an Al alloy core material, an Al-Si brazing material joined to one side of the core material, and the other surface of the core material. An Al—Zn-based lining material, wherein the Al—Zn-based lining material has a Zn amount X (wt%) of 0.5 to 1.0 and a thickness Y (μm) of 30 to 70. And the product XY is 25-70.

  The aluminum alloy heat exchanger according to the present invention includes an Al alloy core material, a tank having an Al-Si brazing material joined to the core material, an Al alloy core material, and a hot material between the core material. And a header plate formed by molding a brazing sheet comprising an Al—Zn-based lining clad by rolling, and the Zn amount X (wt%) of the Al—Zn-based lining material is 0.5. -1.0, thickness Y ([mu] m) is 30-70 and product XY is 25-70, and the Al-Si brazing filler metal part and the Al-Zn lining material are brazed together A hollow structure is formed by joining to form a heat exchanger medium passage.

  Furthermore, in the method for manufacturing an aluminum alloy heat exchanger according to the present invention, a brazing sheet is produced by bonding an Al—Si brazing material to one side of an Al alloy core and clad an Al—Zn lining material on the other side. The brazing sheet is molded as a tank, and an Al-Si brazing material is bonded to one side of the Al alloy core, and an Al-Zn lining material is clad on the other side to form a brazing sheet. The header plate molding process in which the produced brazing sheet is molded as a header plate, and the Al—Si brazing material constituting the tank and the Al—Zn lining material constituting the header plate are joined together. A bonding step of forming a hollow structure and forming a heat exchanger medium passage, and an Al-Zn system in a brazing sheet used in the header material molding step Stretched member of Zn content X (wt%) is 0.5 to 1.0, the thickness Y ([mu] m) there is and the product XY a 30-70, characterized in that 25 to 70.

  The temperature of clad hot rolling performed by superposing a core material, an Al—Zn-based lining material, and an Al—Si-based brazing material to produce a brazing sheet to be molded as the header plate is set to 450 to 470 ° C. Is desirable. Moreover, it is desirable to perform the said joining process by brazing at 580-600 degreeC.

[Action]
As shown in FIG. 4, when the amount of Zn in the lining material before brazing is large and the cladding ratio is high, the amount of Zn in the lining material after brazing increases at the joint J, compared to the brazing material. However, it becomes baseless in potential and corrodes preferentially and leads to leakage.
On the other hand, as shown in FIG. 5, when the amount of Zn in the lining material before brazing is reduced and the cladding ratio is lowered, the amount of Zn in the lining material after brazing is reduced at the joint J, Since it is equal in potential to the brazing material, the brazing material and the lining material are evenly corroded, and there is no preferential corrosion of the lining material and no through leakage occurs.
However, when the Zn content of the general portion G of the lining material and the entire joint portion J is reduced, the anticorrosion function of the lining material of the general portion G is impaired, and a through hole is formed early in the general portion G.

  Therefore, in the present invention, as a result of examining the Zn diffusion profile in the joint portion J, the Zn amount X (wt%) of the Al—Zn-based lining material is 0.5 to 1.0, and the thickness Y (μm) is By setting the product XY when it is 30 to 70 to 25 to 70, the lining material of the header / tank junction does not have an excessive Zn concentration at the boundary B with the brazing material, and the lining material By optimizing the Zn amount of the general part G and the entire joint J, it is possible to prevent early penetration of both the general part G and the joint J.

  According to the brazing sheet for an aluminum alloy heat exchanger, the aluminum alloy heat exchanger, and the aluminum alloy heat exchanger manufacturing method of the present invention, it is possible to achieve an optimal balance between the Zn content in the general part and the header / tank joint. In addition, the preferential corrosion of the general part and the header / tank joint can be prevented with an inexpensive and rational structure, and early occurrence of through-hole corrosion can be prevented in each part.

  The reasons for limiting the Zn content and thickness of the lining material in the brazing sheet for an aluminum alloy heat exchanger of the present invention will be described below. The amount of Zn limited here is that at the stage of becoming a clad material and before brazing. The reason for this limitation is that Zn is easy to diffuse and the amount of Zn may change during clad rolling and may also change during brazing.

(I) The composition of the brazing sheet for an aluminum alloy heat exchanger of the present invention The brazing sheet for an aluminum alloy heat exchanger of the present invention is an Al alloy core material, an Al-Si brazing material bonded to one side of the core material, An Al—Zn-based lining material clad by hot rolling on the other surface of the core material.
(I) The Zn amount X (wt%) of the Al—Zn-based lining material is set to 0.5 to 1.0.
Zn is dissolved in an aluminum alloy, the natural electrode potential of the brazing material is made base to prevent corrosion of the core material, and the corrosion resistance of the tube is improved. However, if the amount of Zn is large, the Zn concentration after brazing becomes high at the header / tank junction, and preferential corrosion of the lining material occurs.
If the added amount of Zn is less than 0.5 wt%, penetration corrosion will occur early in the general part G in contact with the cooling water flowing through the heat exchanger medium passage 7 of the header material.
On the other hand, if it exceeds 1.0 wt%, the corrosion resistance of the general part G in contact with the cooling water becomes good, but the preferential corrosion of the header / tank joint is promoted. Therefore, the addition amount of Zn is defined as 0.5 wt% to 1.0 wt%.

(Ii) The thickness Y (μm) of the Al—Zn lining material is set to 30 to 70.
The amount of Zn in the liner at the header / tank junction after brazing is related not only to the amount of Zn in the header liner but also to the cladding thickness (μm).
When the clad thickness Y (μm) is less than 30 (μm), 1.0 wt% is required in order to obtain a sufficient Zn amount that does not cause penetration corrosion at an early stage in the general part G in contact with the cooling water. Therefore, it is necessary to make the amount of Zn more than the amount of Zn.
When the excess Zn amount exceeds 1.0 wt%, an appropriate balance for preventing penetration leakage is suppressed by suppressing the Zn amount after brazing in the lining material of the header / tank joint. It is not possible.

(Iii) The product XY of Zn amount X (wt%) and thickness Y (μm) of the Al—Zn-based lining material is set to 25 to 70.
A sufficient amount of Zn that does not cause penetration corrosion at an early stage in the general part G that is in contact with the cooling water is prevented, and the amount of Zn after brazing is suppressed in the lining material of the header / tank joint to prevent penetration leakage. The product XY was adopted as an index for achieving an appropriate balance, and this was set to 25-70.

When the product XY of the Zn amount and the cladding thickness is less than 25, the diffusion distance of Zn in the core material direction is small and the diffusion proceeds easily. Therefore, as shown in the Zn diffusion profile of FIG. Even at the boundary B with the highest brazing material 6c, Zn after brazing becomes less than 0.2%.
As a result, since the brazing material and the lining material are equal in potential at the header / tank junction, the brazing material and the lining material are evenly corroded, and the preferential corrosion of the lining material is eliminated, resulting in through leakage. do not do.

  However, on the other hand, the Zn content in the general part G that is in contact with the cooling water other than the header / tank joint is less than 0.25%, so that the sacrificial corrosion effect cannot be exhibited and the general part G in contact with the cooling water. This causes penetration corrosion at an early stage.

  On the other hand, when the product XY of the Zn amount and the cladding ratio exceeds 70, the corrosion of the general part G in contact with the cooling water becomes good. However, in that case, as shown in the Zn diffusion profile of FIG. 4, when the Zn concentration is highest at the boundary B with the brazing material 6c, and the Zn amount X (wt%) before brazing is 0.5 to 1.0, At the boundary B, the Zn content after brazing exceeds 0.55%. As a result, it becomes lower in potential than the brazing material at the header / tank junction, and the lining material preferentially corrodes at the header / tank junction, leading to penetration leakage.

  As described above, considering the Zn diffusion profile in brazing depending on the diffusion energy and diffusion distance due to heating, the product XY of the Zn content of the lining material before brazing of the header material and the cladding thickness (μm) By setting the value to 25 to 70, the amount of Zn at the boundary B with the brazing material 6c at the header / tank junction after brazing can be suppressed to 0.2 to 0.55% to achieve an appropriate balance. It becomes possible. That is, the corrosion resistance of the header / tank junction is improved, and the Zn content of the lining material is 0.25% or more in the general portion G, so that the corrosion resistance of the general portion G can be ensured.

(II) Manufacturing Process of Brazing Sheet for Aluminum Alloy Heat Exchanger of the Present Invention The manufacturing process of the brazing sheet material proposed in the present invention is performed at a temperature of the clad hot rolling (from start to finish) from 450 ° C. Perform at 470 ° C.
This is done by hot rolling in this temperature range, so that Zn of the lining material is pre-diffused into the core material by preheating during hot rolling or temperature rise during rolling, and header material / tank header during brazing heating / This is to reduce the Zn content of the lining material at the tank joint. However, particularly in the temperature range exceeding 500 ° C., the temperature rise of the lining material / outer brazing material due to rolling is higher than that of the core material, so that the diffusion of Zn in the lining material becomes too large. For this reason, the amount of Zn in the lining material is reduced at the header material / tank header / tank joint, and corrosion of the header / tank joint is not a problem, but after brazing at the general part G in contact with the cooling water, Zn Since the amount is less than 0.25%, the sacrificial corrosion effect of the lining material is reduced, and there is a problem that the general part penetrates early.

(III) Zn content in each production stage of the brazing sheet for an aluminum alloy heat exchanger of the present invention In the brazing sheet for an aluminum alloy heat exchanger of the present invention manufactured through the above manufacturing steps, the Zn content is At each manufacturing stage, the following occurs.
(I) Skin ingot
0.5-1.0% is required. This is because it is necessary to satisfy the Zn content condition from the viewpoint of preferential corrosion and sacrificial effect after brazing.
(Ii) Brazed sheet in the clad state after production If the temperature of the clad hot rolling is too high, the amount of Zn in the ingot is reduced, but a sufficient sacrificial effect cannot be obtained after brazing. Therefore, 0.5-1.0% is required after brazing and before brazing.
(Iii) Header / tank joint after brazing From the viewpoint of preventing preferential corrosion of the header / tank joint, it is necessary to be less than 0.55%.
(Iv) General part G after brazing
In order to obtain a sufficient sacrificial anticorrosive effect, it is necessary to be 0.25% or more.

(IV) Aluminum Alloy Heat Exchanger of the Present Invention As shown in FIGS. 1 (a) and 1 (b), the aluminum alloy heat exchanger 1 of the present invention is molded from the brazing sheet for an aluminum alloy heat exchanger of the present invention. The Al—Si brazing material 6 c and the Al—Zn lining material 4 b are joined by brazing to form a hollow structure, thereby forming a heat exchanger medium passage 7. The heat exchanger medium passage 7 is formed by brazing at 580 to 600 ° C.

(V) Manufacturing method of aluminum alloy heat exchanger of the present invention The aluminum alloy heat exchanger 1 of the present invention described above is manufactured by the following steps.
An Al-Si brazing material 6c is joined to one side of the Al alloy core material 6a, and an Al-Zn lining material 6b is clad on the other side to produce a brazing sheet. The produced brazing sheet is used as a tank (6A), (6B) A tank molding step for molding is performed.

Also, an Al—Si brazing material 4c is joined to one side of the Al alloy core material 4a, and an Al—Zn lining material 4b is clad on the other side to produce a brazing sheet. The produced brazing sheet is used as a header material plate. The header material plate molding process to be molded as 4 is performed.
The brazing sheet for an aluminum alloy heat exchanger according to the present invention is used as the brazing sheet.

  A heat exchanger medium passage is formed by forming a hollow structure so that the Al—Si brazing material 6c constituting the tanks (6A) and (6B) and the Al—Zn lining material 4b constituting the header material plate 4 are joined. 7 is performed by brazing at 580 to 600 ° C.

[Example]
Table 1 shows the lining material component and cladding ratio in the header material of the present invention example, and the comparative example lining material component that deviates from the present invention example. These lining material, core material alloy (JIS3003 alloy) and inner brazing material (BA4343P alloy (referred to as inner brazing material) are cast in ingot size width 600mm, length 5000mm, width 1200mm. The brazing material is rolled at a hot rolling start temperature of 500 ° C. so as to have a predetermined cladding ratio, and then superposed so as to have a predetermined cladding ratio. The cladding hot rolling start temperature is 460 ° C. and the end temperature is 470 ° C. A brazing sheet was produced by rolling and cold rolling to a final plate thickness of 1.0 mm for 1 hour at a final annealing temperature of 400 ° C. As a comparative example, the composition of the lining material alloy The product XY of the Zn amount and the clad thickness is within the range of the present invention example, but the clad hot rolling start temperature is 520 ° C., the end temperature is 530 ° C., and cold rolling is 1.0 mm. Also , The brazing sheet the final annealing temperature was carried out for 1 hour at 400 ° C. were also prepared.

  As a tank material to be joined with these header materials, a BAS311P (core material: JIS3003 alloy, inner brazing material: JIS4343 alloy, lining material: JIS7072 alloy) plate thickness of 1.0 mm and O tempered material was used.

(1) Corrosion test As a corrosion test of the header / tank joint, the header material having the structure shown in Table 1 was processed into a test piece having a width of 25 mm and a length of 100 mm, and the lining material of the header material and the tank material (BAS311P: plate thickness) 1.0 mm) brazing material is joined with a joining area width of 25 mm and length of 20 mm, and after heating equivalent to brazing (3 minutes at 600 ° C.) under a nitrogen atmosphere, the joining surface remains and the back and end portions. After masking, a CASS test according to JISH8601 was performed to remove corrosion products, and then the corrosion depth of the header / tank junction was measured by the depth of focus method. Further, as a general part corrosion test, the header material having the structure shown in Table 1 was processed into a test piece having a width of 25 mm and a length of 100 mm, and brazed and heated (600 ° C. for 3 minutes) in a nitrogen atmosphere. The lining material is left with a width of 20 mm and a length of 80 mm, and after masking the end portion and the back surface, OY water (Cl-: 195 ppm, SO ₄ ^2- : 60 ppm, Cu ² +: 1 ppm, Fe ³ +: 30 ppm) ), And subjected to a test in which a heat cycle of 88 ° C. × 8 hours of heating and 16 hours of cooling was repeated for 3 months. After the test, after removing the corrosion products, the corrosion depth was measured by the depth of focus method. The results are shown in Table 1.

  As can be seen from Table 1, in Example 1 of the present invention, the Zn (wt%) at the header material ingot stage was 0.52, the Zn (wt%) before brazing the header material was 0.51, and the header liner The material thickness (μm) was 70. The product XY of the amount of Zn before brazing and the cladding ratio is 35.7, the amount of Zn in the header liner at the header / tank joint after brazing is 0.27, and the header in the general part after brazing The amount of Zn in the lining material was 0.35. As a result, the corrosion depth (mm) of the header / tank junction was 1.1, and the corrosion depth (mm) of the general part was 0.05.

  In Example 2 of the present invention, Zn (wt%) at the header material ingot stage is 0.72, Zn (wt%) before brazing the header material is 0.70, and the thickness of the header lining material (μm) is 0.72 50. The product XY of the amount of Zn before brazing and the cladding ratio is 35.0, the amount of Zn in the header liner at the header / tank joint after brazing is 0.26, and the header in the general part after brazing The amount of Zn in the lining material was 0.34. As a result, the corrosion depth (mm) of the header / tank junction was 1.4, and the corrosion depth (mm) of the general part was 0.05.

  In Example 3 of the present invention, the Zn (wt%) at the header material ingot stage is 0.73, the Zn (wt%) before brazing the header material is 0.71, and the header lining material thickness (μm) is 70. The product XY of the amount of Zn before brazing and the cladding ratio is 49.7, the amount of Zn in the header liner at the header / tank joint after brazing is 0.37, and the header in the general part after brazing The amount of Zn in the lining material was 0.48. As a result, the corrosion depth (mm) of the header / tank junction was 1.5, and the corrosion depth (mm) of the general part was 0.10.

  In Example 4 of the present invention, the Zn (wt%) at the header material ingot stage is 0.95, the Zn (wt%) before brazing the header material is 0.93, and the thickness of the header lining material (μm) is 50. The product XY of the amount of Zn before brazing and the cladding ratio is 46.5, the amount of Zn in the header liner at the header / tank joint after brazing is 0.35, and the header in the general part after brazing The amount of Zn in the lining material was 0.45. As a result, the corrosion depth (mm) of the header / tank junction was 1.5, and the corrosion depth (mm) of the general part was 0.04.

  In Example 5 of the present invention, the Zn (wt%) at the header material ingot stage is 0.99, the Zn (wt%) before brazing the header material is 0.97, and the header lining material thickness (μm) is 70. The product XY of the amount of Zn before brazing and the cladding ratio is 67.9, the amount of Zn in the header liner at the header / tank joint after brazing is 0.51, and the header in the general portion after brazing The amount of Zn in the lining material was 0.66. As a result, the corrosion depth (mm) of the header / tank junction was 2.1, and the corrosion depth (mm) of the general part was 0.04.

  In Example 6 of the present invention, the Zn (wt%) at the header material ingot stage is 0.53, the Zn (wt%) before brazing the header material is 0.52, and the header lining material thickness (μm) is 50. The product XY of the amount of Zn before brazing and the cladding ratio is 26.0, the amount of Zn in the header liner at the header / tank joint after brazing is 0.20, and the header in the general part after brazing The amount of Zn in the lining material was 0.25. As a result, the corrosion depth (mm) of the header / tank junction was 0.9, and the corrosion depth (mm) of the general part was 0.08.

In Example 7 of the present invention, the Zn (wt%) at the header material ingot stage is 0.98, the Zn (wt%) before brazing the header material is 0.96, and the header lining material thickness (μm) is 30. The product XY of the amount of Zn before brazing and the cladding ratio is 28.8, the amount of Zn in the header liner at the header / tank joint after brazing is 0.22, and the header in the general portion after brazing The amount of Zn in the lining material was 0.28. As a result, the corrosion depth (mm) of the header / tank junction was 1.2, and the corrosion depth (mm) of the general part was 0.08.
Therefore, it can be seen that all of the above examples of the present invention satisfy the conditions of the present invention, the preferential corrosion does not occur at the header / tank junction, the corrosion resistance of the general part is good, and the optimum balance is achieved.

  In Comparative Example 8, the Zn (wt%) at the header material ingot stage was 0.45, the Zn (wt%) before brazing the header material was 0.44, and the header lining material thickness (μm) was 50. Met. The product XY of the amount of Zn before brazing and the cladding ratio is 22.0, the amount of Zn in the header liner at the header / tank junction after brazing is 0.11, and the header in the general part after brazing The amount of Zn in the lining material was 0.14. Therefore, in Comparative Example 8, the Zn content in the header material was less than the present invention in which the Zn content in the Al—Zn-based lining material (2b) was 0.5 to 1.0%. Moreover, since the product XY of the Zn content (wt%) and the cladding thickness of the header material was less than 25, the corrosion depth (mm) of the header / tank junction was 0.8 and no corrosion occurred. Penetration corrosion occurred in the general part in contact with.

  In Comparative Example 9, the Zn (wt%) at the header material ingot stage was 0.51, Zn (wt%) before brazing the header material was 0.50, and the header lining material thickness (μm) was 30. Met. The product XY of the amount of Zn before brazing and the cladding ratio is 15.0, the amount of Zn in the header liner at the header / tank joint after brazing is 0.11, and the header in the general part after brazing The amount of Zn in the lining material was 0.15. As a result, the Zn content of the lining material is within the scope of the present invention, but the header / tank junction does not corrode because the product XY of the Zn content (wt%) of the header material and the cladding thickness was less than 25. (Corrosion depth (mm) was 0.8), however, penetration corrosion occurred in the general part in contact with the cooling water.

  In Comparative Example 10, the Zn (wt%) at the header material ingot stage was 0.70, the Zn (wt%) before brazing the header material was 0.68, and the header lining material thickness (μm) was 30. Met. The product XY of the amount of Zn before brazing and the cladding ratio is 20.4, the amount of Zn in the header liner at the header / tank joint after brazing is 0.12, and the header in the general part after brazing The amount of Zn in the lining material was 0.16. As a result, as in Comparative Example 9, the Zn content of the lining material is within the scope of the present invention, but the product XY of the Zn content (wt%) of the header material and the cladding thickness was less than 25, so the header / tank Although no corrosion occurred at the joint (corrosion depth (mm) was 1.0), penetration corrosion occurred at the general part in contact with the cooling water.

  In Comparative Example 11, Zn (wt%) at the header material ingot stage was 0.98, Zn (wt%) before brazing the header material was 0.98, and the header lining material thickness (μm) was 100. Met. The product XY of the amount of Zn before brazing and the cladding ratio is 98.0, the amount of Zn in the header liner at the header / tank junction after brazing is 0.74, and the header in the general part after brazing The amount of Zn in the lining material was 0.96. As a result, the Zn content of the lining material is within the range of the present invention, but the product XY of the Zn content (wt%) of the header material and the cladding thickness exceeded 70, so that Al—Zn at the header / tank junction was obtained. Preferential corrosion occurred in the alloy layer, resulting in penetration corrosion.

  In Comparative Example 12, the Zn (wt%) in the header material ingot stage was 1.20, the Zn (wt%) before brazing the header material was 1.15, and the header lining material thickness (μm) was 70. Met. The product XY of the amount of Zn before brazing and the cladding ratio is 80.5, the amount of Zn in the header liner at the header / tank joint after brazing is 0.60, and the header in the general part after brazing The amount of Zn in the lining material was 0.78. As a result, the Zn content of the lining material exceeded the present invention, and the product XY of the Zn content (wt%) of the header material and the cladding thickness exceeded 70, so the Al—Zn alloy layer at the header / tank junction Caused preferential corrosion and lead to through corrosion.

  In Comparative Example 13, the Zn (wt%) at the header ingot stage was 0.75, the Zn (wt%) before brazing the header material was 0.44, and the header lining material thickness (μm) was 70. Met. The product XY of the amount of Zn before brazing and the cladding ratio is 30.8, the amount of Zn in the header liner at the header / tank joint after brazing is 0.12, and the header in the general part after brazing The amount of Zn in the lining material was 0.16. In Comparative Example 13, since the clad hot rolling start temperature was 520 ° C. and the end temperature was 530 ° C., the amount of Zn in the brazing sheet forming the header material was reduced (in the general part, the Zn of the lining material) The amount was less than 0.25%), and no corrosion occurred at the header / tank junction, but through corrosion occurred at the general part in contact with the cooling water.

Fig.1 (a) is a front view of the heat exchanger (radiator) for motor vehicles, FIG.1 (b) is the AA cross-section enlarged schematic diagram of Fig.1 (a). Explanatory drawing which shows Zn diffusion profile in the header / tank junction part between a tank and header material plates. Cross section of header / tank joint between tank and header plate. It is explanatory drawing which shows an example of Zn diffusion profile in the header / tank junction part between a tank and a header material plate, (a) shows before brazing, (b) shows after brazing. It is explanatory drawing which shows the other example of Zn diffusion profile in the header / tank junction part between a tank and header material plates, (a) is before brazing, (b) shows after brazing.

Explanation of symbols

2 ... tube, 6 ... tank, 4 ... header plate, 6a, 4a ... core material 6c ... brazing material, 4b ... lining material, J ... joint, G ... General part.

Claims (7)

  An Al alloy core material, an Al-Si brazing material bonded to one side of the core material, and an Al-Zn lining material clad by hot rolling on the other surface of the core material, The Zn amount X (wt%) of the Al—Zn-based lining material is 0.5 to 1.0, the thickness Y (μm) is 30 to 70, and the product XY is 25 to 70. A brazing sheet for an aluminum alloy heat exchanger.   The brazing sheet for an aluminum alloy heat exchanger according to claim 1, wherein the Al-Zn lining material is clad by hot rolling at 450 to 470 ° C. A tank having an Al alloy core material and an Al-Si brazing material part bonded to the core material;
A header plate formed by molding a brazing sheet comprising an Al alloy core material and an Al-Zn-based lining material clad by hot rolling on the core material;
In the brazing sheet, the amount of Zn X (wt%) in the stage before brazing of the Al—Zn-based lining material is 0.5 to 1.0, the thickness Y (μm) is 30 to 70, and The product XY is 25-70,
An aluminum alloy heat exchanger characterized in that the Al-Si brazing filler metal part and the Al-Zn lining material are joined by brazing to form a hollow structure to serve as a heat exchanger medium passage.   The heat exchanger made of aluminum alloy according to claim 3, wherein the heat exchanger medium passage is formed by brazing at 580 to 600 ° C. A tank molding step in which an Al-Si brazing material is joined to one side of an Al alloy core, an Al-Zn lining material is clad on the other side to produce a brazing sheet, and the produced brazing sheet is molded as a tank; ,
Header plate molding in which an Al-Si brazing material is joined to one side of an Al alloy core, an Al-Zn lining material is clad on the other side to produce a brazing sheet, and the produced brazing sheet is molded as a header plate Process,
A bonding step of forming a hollow structure so that the Al-Si brazing material constituting the tank and the Al-Zn lining material constituting the header plate are joined to form a heat exchanger medium passage, In the brazing sheet used in the header material molding step, the amount of Zn X (wt%) of the Al—Zn lining material is 0.5 to 1.0, the thickness Y (μm) is 30 to 70, and the product XY is 25-70, The manufacturing method of the heat exchanger made from an aluminum alloy characterized by the above-mentioned. The temperature of clad hot rolling performed by superimposing a core material, an Al-Zn-based lining material, and an Al-Si-based brazing material to produce a brazing sheet to be molded as the header plate is set to 450 to 470 ° C. Item 6. A method for producing an aluminum alloy heat exchanger according to Item 5. The method for producing an aluminum alloy heat exchanger according to claim 5 or 6, wherein the joining step is performed by brazing at 580 to 600 ° C.

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