JPH09296243A - Brazing sheet made of aluminum alloy - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a brazing sheet made of an Al alloy excellent in corrosion resistance and suitable for a heat exchanger jointly assembled by vacuum brazing. SOLUTION: As for the constitution of this brazing sheet made of an Al alloy, both sides of an Al allay core material 5 contg., by mass, 0.5 to 2.0% Mn, 0.1 to 1.0% Cu, 0.05 to 0.5% Mg, 0 to 0.3% Ti, and the balance Al with inevitable impurities are clad with Al-Si-Mg brazing filler metals at a cladding rate of 5 to 20%, and furthermore, the space between the brazing filler metal 3 and the core material 5 equivalent to the tank part of a heat exchanger and the outer face C of a refrigerant passage is provided with an intermediate layer 4 composed of an Al alloy contg. 0.5 to 2.0% Mn, 0.05 to 0.5% Mg, 0 to 0.3% Ti, and the balance Al with inevitable impurities and having >=30μm, preferably, >=80μm at a cladding rate of <=35%.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aluminum alloy heat exchanger or the like for automobiles and various industries, which is suitable for brazing, particularly for vacuum-brazing joining and assembling, and is excellent in corrosion resistance. The present invention relates to an alloy brazing sheet. In the present specification, the composition of Al alloy is all mass%, but it will be abbreviated as simply%.

[0002]

2. Description of the Related Art Brazing is an effective means for manufacturing a complex structure made of an aluminum alloy. Vacuum brazing, which does not require a flux, has been actively carried out since there is no concern about pollution. Have been done. Vacuum brazing is Al or A
1 alloy is used as a core material, and one or both surfaces are formed into various shapes using a brazing sheet clad with an Al alloy brazing material as a skin material, and these members are assembled into a predetermined structure, for example, a heat exchanger. This is a method of brazing by heating in a vacuum.

[0003] Brazing sheets for vacuum brazing include:
Various Al alloys for the core material and Al alloy brazing materials for the skin material have been developed, and these materials are now JIS-Z-326.
3 and JIS-H-4000.
As a brazing sheet for vacuum brazing used in a heat exchanger, JIS3003 (a typical example of Al-
0.15% Cu-1.1% Mn alloy), JIS3005
(Representative example: Al-1.1% Mn-0.4% Mg alloy), J
IS3105 (Representative example: Al-0.6% Mn-0.6% M
g alloy) as a skin material according to JIS4004 (typical example of Al-
10% Si-1.5% Mg alloy), JIS4104
(Representative example Al-10% Si-1.2% Mg-0.1% B
It is usual to use an i-alloy) brazing material. The brazing sheet has a thickness of about 0.3 to 1.5 mm,
The brazing material has a clad ratio of 5 to 1 on one side relative to the total plate thickness.
5%, clad on one or both sides.

As a heat exchanger made of an aluminum alloy having a hollow structure using such a brazing sheet, a drone cup type evaporator, an oil cooler, a radiator and the like are manufactured. For example, as shown in FIG. 4, a drone cup type evaporator 10 uses a brazing sheet in which the Al alloy brazing material is clad on both surfaces of the Al alloy core material to form a refrigerant passage as shown in FIGS. 2 and 3. The molded member 1 is manufactured by press molding, the members 1 are laminated as shown in FIG. 4, the corrugated fins 2 are arranged between the laminated members 1, and the side plates 6 ^, 6,, the refrigerant inlet pipe 7, The refrigerant outlet pipe 8 is provided and assembled, and this is vacuum brazed. Brazing is performed at 1.3 × 10 ^-3 to
It is performed by heating to about 873K in a vacuum of about 1.3 × 10 ⁻² Pa.

[0005]

With the reduction in the weight of automobiles, it has been required that these heat exchangers be made thinner. On the other hand, since the use environment of automobiles varies, materials that can withstand all use conditions are required. In particular, in the case of a drone cup type heat exchanger having no sacrificial layer, the corrosion resistance of the core material of the brazing sheet is the most important required property for the material, and the development of a corrosion resistant brazing sheet has been eagerly studied and various studies are being conducted. .

[0006] The corrosion resistance of a brazing sheet is related to the distribution of elements in the thickness direction of the material. Elements that contribute to the corrosion resistance of the material, such as Cu and Zn, are located at the center of the thickness when brazing heating is performed. The distribution is symmetrical about the axis. Therefore, when pitting occurs on the surface of the brazing sheet, the material whose pitting progresses on the surface side slower than the center of the plate thickness has a faster pitting progress after passing through the center of the plate thickness. In other words, it is not an exaggeration to say that the part contributing to the improvement of the corrosion resistance is half the plate thickness, and there is a limit to the improvement of the penetration life by the addition of the element to the core material.

Further, the addition of Cu increases the potential of aluminum, so that it is added to the core material of the brazing sheet for the purpose of improving corrosion resistance. However, Cu added to the core material diffuses into the brazing material melted during the brazing heating, and is discharged and concentrated to the eutectic portion when the brazing material solidifies after the brazing heating. Therefore, as the brazing sheet has more Cu in the core material, the layer in which the brazing material is re-solidified is corroded more quickly. Therefore, there is a limit to the amount of elements such as Cu for improving the corrosion resistance of the core material of the brazing sheet.

Conventionally, for the purpose of preventing the diffusion of the brazing material into the core material at the time of heating by brazing, for example, as disclosed in JP-A-2-30394, a five-layer structure in which an intermediate layer is provided between the core material and the brazing material. A brazing sheet of material has been proposed. In this proposal,
In order to make the potential lower than the core material in consideration of the sacrificial corrosion protection effect,
The 1XXX alloy is used as the intermediate layer. However, this brazing sheet was still insufficient in terms of corrosion resistance. An object of the present invention is to solve the above-mentioned problem of improvement in corrosion resistance, and specifically to find an Al alloy brazing sheet that is more excellent in terms of corrosion resistance.

[0009]

As a result of intensive studies to solve the above problems, the present inventors have found that in order to improve the corrosion resistance of a brazing sheet member, a brazing filler metal is added during brazing and heating. In order to prevent the diffusion of Cu and other elements such as Cu in the core material to the brazing material, an intermediate layer is provided between the brazing material and the core material, and the alloy composition, thickness and clad ratio of this intermediate layer are brazed. The present invention has been completed based on the finding that it is greatly related to the corrosion resistance of the sheet.

[0010] That is, the invention of claim 1 for solving the above-mentioned problem is to provide an aluminum alloy brazing sheet for a heat exchanger, which forms a tank portion and a refrigerant passage by joining press-formed brazing sheets by vacuum brazing. The composition is as follows: Mn: 0.5 to 2.0%, Cu: 0.
1 to 1.0%, Mg: 0.05 to 0.5%, Ti: 0 to 0%
An Al alloy core material containing 0.3% and the balance Al and unavoidable impurities, and an Al-Si-Mg alloy brazing material on both surfaces thereof with a clad ratio of 5 to 20%, and further, the tank portion. And between the brazing material and the core material corresponding to the outer surface of the refrigerant passage, Mn: 0.5 to 2.0%, Mg: 0.05 to
An Al alloy containing 0.5%, Ti: 0 to 0.3%, the balance being Al and unavoidable impurities, and having an thickness of 30 μm or more and a cladding rate of 35% or less. A brazing sheet made of Al alloy characterized by being provided,

The invention of claim 2 has a thickness of 80 μm.
The Al alloy brazing sheet according to claim 1, further comprising an intermediate layer having a cladding rate of 35% or less.

Further, the invention of claim 3 is based on Al-Si-
The brazing sheet made of Al alloy according to claim 1 or 2, wherein the Mg-based brazing material further contains Sn of 0.05 to 0.5%.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in more detail below. First, the Al alloy brazing sheet according to the first aspect of the present invention will be described. The significance of the additive element of the Al alloy used for the core material of this brazing sheet and the reason for limiting the range are as follows. Cu is added in an amount of 0.1 to 1.0% in order to improve the corrosion resistance. However, if its content is less than the lower limit, the effect is weak, and if it exceeds the upper limit, intergranular corrosion is easily generated, and the core material of the brazing material is used. Therefore, the corrosion resistance is reduced because the amount of diffusion into the steel increases. Therefore, the range is 0.1 to 1.0%, and more preferably 0.15 to 0.5%.

Mn is 0.5 to 2.0 for improving strength.
However, if the amount is less than the lower limit, the effect of improving the strength is small. If the amount exceeds the upper limit, the amount of diffusion of the brazing material into the core material during brazing heating increases, thereby deteriorating brazing properties and corrosion resistance. Therefore, the range is 0.5 to 2.0%,
More preferably, it is 0.8 to 1.5%.

Mg is added in an amount of 0.05-0.
5% is added, but if it is less than the lower limit, the effect of improving the strength is small, and if it exceeds the upper limit, the amount of diffusion of the brazing material into the core material during brazing heating increases, thereby deteriorating brazing properties and corrosion resistance. Therefore, the range is 0.05-0.5%,
More preferably, it is 0.1 to 0.3%.

[0016] Ti is 0 to improve the corrosion resistance.
Add 0.3%. The meaning of 0 to 0.3% is 0% (0.
(Less than 01%) is not added at all, and when added, the content is 0.01 to 0.3%. If the addition amount exceeds 0.3%, coarse Ti crystals are formed, which adversely affects corrosion resistance. Therefore, the range of Ti is set to 0 to 0.3%, but whether to add Ti is determined by appropriately selecting according to the use of the product. In addition, when adding, it is more preferable to set it to about 0.05 to 0.2%.

Elements other than those mentioned above and inevitable impurities in the core material include Si, Fe, Cr, Zn, etc., but generally accepted ranges, that is, Si is 0.6% or less and Fe is 0.7% or less. , Cr is 0.20% or less, Zn is 0.40
If it is less than%, there is no particular problem. However, regarding Si and Fe, Si 0.20% or less and Fe 0.20% or less are more preferable.

Next, the significance of the additive elements of the Al alloy used for the intermediate layer material of the Al alloy brazing sheet according to the present invention and the reasons for limiting the range will be described. Mn is added in an amount of 0.5 to 2.0% for the purpose of improving the strength. However, if it is less than the lower limit, the effect of improving the strength is small, and if it exceeds the upper limit, the diffusion of the brazing material into the core material during brazing heating. Increases the amount and reduces brazing and corrosion resistance. Therefore, the range is 0.5 to 2.0%, more preferably 0.8 to 1.5%.

Mg is added in an amount of 0.05 to 0.
5% is added, but if it is less than the lower limit, the effect of improving the strength is small, and if it exceeds the upper limit, the amount of diffusion of the brazing material into the core material during brazing heating increases, thereby deteriorating brazing properties and corrosion resistance. Therefore, the range is 0.05-0.5%,
More preferably, it is 0.1 to 0.3%.

Ti is 0 to improve the corrosion resistance.
Add 0.3%. The meaning of 0 to 0.3% is 0% (0.
(Less than 01%) is not added at all, and when added, the content is 0.01 to 0.3%. If the addition amount exceeds 0.3%, coarse Ti crystals are formed, which adversely affects corrosion resistance. Therefore, the range of Ti is set to 0 to 0.3%, but when added, it is more preferably set to about 0.05 to 0.2%.

Elements other than those mentioned above in the Al alloy material of the intermediate layer, which are inevitable impurities, include Si, Fe, Cr, and Z.
Although there are n, Cu, etc., generally accepted ranges, that is, Si is 0.6% or less, Fe is 0.7% or less, and Cr is 0.20%.
Hereinafter, as long as Zn is 0.40% or less and Cu is 0.05% or less, there is no particular problem in terms of workability and corrosion resistance. However, for Si and Fe, the content of Si is 0.20% or less,
0.20% or less is more preferable.

Next, in the brazing sheet according to the present invention, the intermediate layer material made of the Al alloy is provided on one side of the core material, that is, on the side corresponding to the outside of the tank portion and the refrigerant passage of the heat exchanger, and further on top of it. The brazing material is clad. In addition,
Usually, the other surface of the core material is directly clad with a brazing material, but is not limited thereto. The reason why the intermediate layer is provided on the side corresponding to the outside of the tank portion and the refrigerant passage is that the outside is more severe in the corrosive environment.
The reason why the thickness of the intermediate layer of the Al alloy brazing sheet according to the present invention is set to 30 μm or more is that when the thickness of the intermediate layer is less than 30 μm, Cu of the core material forms the intermediate layer during brazing heating. This is because it diffuses to the brazing filler metal. The Cu that has reached the brazing material is discharged to the eutectic portion when the brazing material is melted and solidified, and is concentrated, thereby lowering the corrosion resistance.
The reason why the cladding ratio of the intermediate layer is set to 35% or less with respect to the total plate thickness is that if the intermediate layer becomes too thick with respect to the plate thickness,
Because the material strength decreases and molding becomes difficult, and the portion that sacrifices and protects the core material becomes too large, and if corrosion progresses, the remaining plate thickness becomes thin and it cannot withstand the internal pressure of the heat exchanger It is. Therefore, the intermediate layer has a thickness of 30 μm or more and a cladding ratio of 35% or less.

The brazing material used in the present invention is not particularly limited. Al- which is usually used for vacuum brazing
Si-Mg alloy brazing material, ie, 4004 (representative example A of component)
1-10% Si-1.5% Mg alloy), 4104 (Representative example of components: Al-10% Si-1.2% Mg-0.1% B)
i alloy) can be used. As for the clad ratio of the brazing material, a normal clad ratio, that is, 5 to 20% per one side with respect to the entire plate thickness can be used. In addition,
In the case of the present invention, the brazing material is clad on both sides of the plate.

The structure of the Al alloy brazing sheet according to the present invention is as described above. The sectional structure of this sheet (plate) is shown in FIG.
That is, the brazing filler metal 3 is provided on the side C of the Al alloy core material 5 corresponding to the outer surface of the tank portion and the refrigerant passage of the heat exchanger via the intermediate layer 4 made of the Al alloy, and the core material 5 other side brazing material 3 to D (the side corresponding to the inner ^surface), a four-layer structure in which a.

The invention of claim 2 is the Al of the invention of claim 1.
In the alloy brazing sheet, in particular, the intermediate layer is an Al alloy brazing sheet having a thickness of 80 μm or more and a clad ratio of 35% or less. The present invention is a preferred embodiment of the first aspect of the present invention. The reason why the thickness of the intermediate layer is 80 μm or more and the cladding rate is 35% or less is that this range is particularly excellent in terms of corrosion resistance.

The invention of claim 3 relates to claim 1 and claim 2.
In the brazing sheet made of an Al alloy according to the invention,
-Si-Mg based alloy brazing material, Sn further 0.05 ~
0.5% is added. Since Sn is discharged to the eutectic portion when the brazing material solidifies after the brazing heating, the potential of the eutectic portion can be neutralized, and the corrosion resistance of the brazing sheet surface after the brazing heating can be further improved. . When the amount is less than the lower limit, the effect is not obtained. When the amount exceeds the upper limit, the corrosion resistance of the surface after brazing is reduced, and the progress of corrosion is promoted. Therefore, the addition amount is 0.05-0.5%
However, the content is more preferably set to 0.05 to 0.2%. Other requirements are the same as those of the first and second aspects.

[0027]

EXAMPLES Next, examples of the present invention (invention examples) will be described in more detail together with comparative examples. Example 1 Core materials and intermediate layer materials having various alloy compositions shown in Table 1 were prepared. The core material and the intermediate layer material are combined as shown in Table 1, the intermediate layer material is combined on one side of the core material, and the brazing material made of JIS4104 alloy is clad on both surfaces thereof (the cladding ratio is based on the total thickness). 15% per side)
did. The cladding ratio of the intermediate layer was set to 15% of the total thickness. The rolling material thus combined was subjected to soaking, hot rolling, intermediate annealing and cold rolling according to a conventional method to produce a 1.0 mm thick brazing sheet. Table 1 shows the configurations of these various brazing sheets. After the brazing sheets (Nos. 1 to 16) shown in Table 1 thus obtained were washed and finish annealed,
Vacuum brazing was performed at 873 K × 3 minutes in a vacuum of 6.7 × 10 ⁻³ Pa to obtain a test material. One side of each of these test materials was covered with a resin, and a corrosion test (CASS test) was performed.
After 500 hours and 1000 hours from the start of the test, the test material was taken out, the surface corrosion products were removed, and the corrosion state of the material was evaluated. For evaluation, the pitting depth of the maximum pitting portion was measured by the depth of focus method using an optical microscope. For some materials, the corrosion morphology was observed from the cross section. The measurement results are shown in Table 1.

[0028]

[Table 1]

As is clear from Table 1, the brazing sheet according to the present invention is superior in corrosion resistance to the comparative example.

[Example 2] No. 1 shown in Table 1 Using the core material and the intermediate layer material of No. 3, the cladding rate of the intermediate layer material is 2 to 4
Change to various values up to 0%.
A brazing material made of 4104 alloy was clad (the cladding ratio was 15% per one side with respect to the entire plate thickness). The rolling material thus combined was subjected to soaking, hot rolling, intermediate annealing, and cold rolling according to a conventional method to produce brazing sheets having thicknesses of 1.0 mm and 0.5 mm. Table 2 shows the configurations of these various brazing sheets. After cleaning and finish annealing the brazing sheets shown in Table 2, 873K × in a vacuum of 6.7 × 10 ⁻³ Pa.
Vacuum brazing and heating were performed for 3 minutes to obtain a test material. JIS No. 5 test pieces were prepared using these test materials, and the tensile strength was measured. Press molding was performed using these test materials. Whether or not a sufficient molding height was obtained was evaluated by measuring the overhang height of the molded product. Furthermore, one surface of all the test materials was coated with a resin and a corrosion test (CASS test) was performed.
After 500 hours and 1000 hours from the start of the test, the test material was taken out, the surface corrosion products were removed, and the corrosion state of the material was evaluated. For evaluation, the pitting depth of the maximum pitting portion was measured by the depth of focus method using an optical microscope. The measurement results are also shown in Table 2.

[0031]

[Table 2]

As is apparent from Table 2, the brazing sheet according to the present invention has strength comparable to that of the comparative example, excellent moldability, and particularly excellent corrosion resistance.

[Example 3] As shown in Table 3, various core materials and intermediate layer materials were combined and combined, and JIS4104 alloy was further added with Sn in an amount of 0.05 to 0.05% on both surfaces thereof.
A brazing material containing 0.6% was clad (the cladding ratio was 15% per one side with respect to the entire plate thickness). Soaking according to the conventional method for the material for rolling thus adjusted,
Hot rolling, intermediate annealing and cold rolling are performed to a thickness of 1.0
mm brazing sheet was produced. Table 3 shows the configurations of these various brazing sheets. After cleaning and finishing annealing these brazing sheets shown in Table 3,
Vacuum brazing was performed at 873 K × 3 minutes in a vacuum of 6.7 × 10 ⁻³ Pa to obtain a test material. One side of each of these test materials was covered with a resin, and a corrosion test (CASS test) was performed.
After 500 hours and 1000 hours from the start of the test, the test material was taken out, the surface corrosion products were removed, and the corrosion state of the material was evaluated. For evaluation, the pitting depth of the maximum pitting portion was measured by the depth of focus method using an optical microscope. Table 3 also shows the measurement results.

[0034]

[Table 3]

As is clear from Table 3, the brazing sheet according to the present invention is superior in corrosion resistance as compared with the comparative example.

[0036]

As described in detail above, the present invention can significantly improve the corrosion resistance of one side of a corrosive environment which is severe in the use of an Al alloy brazing sheet. In this case, the corrosion life of the heat exchanger can be remarkably improved, and this has an industrially remarkable effect.

[Brief description of drawings]

FIG. 1 is a diagram showing a cross-sectional structure of an Al alloy brazing sheet according to the present invention.

FIG. 2 is a plan view showing a refrigerant passage forming member for a drone cup evaporator.

FIG. 3 is a sectional view taken along line B-B 'of FIG.

FIG. 4 is an explanatory view showing an example of a heat exchanger (Drone cup evaporator), and is a schematic sectional view thereof.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 refrigerant forming member for drone cup evaporator 2 fin 3 ^, 3 ^, brazing material 4 intermediate layer material 5 core material 6 ^, 6 ^, side plate 7 refrigerant inlet tube 8 refrigerant outlet tube 10 heat exchanger (dron cup evaporator) C heat Side corresponding to the outside of the tank part and the refrigerant passage of the exchanger D Side corresponding to the inside of the tank part and the refrigerant passage of the heat exchanger

 ─────────────────────────────────────────────────── ─── Continued front page (72) Inventor Noboru Soga 2-6-1, Marunouchi, Chiyoda-ku, Tokyo Furukawa Electric Co., Ltd. (72) Inventor Haruhiko Miyaji 1-1-1, Showa-cho, Kariya city, Aichi Japan Inside Denso Co., Ltd. (72) Inventor Eiichi Torikoshi 1-1, Showa-cho, Kariya city, Aichi Prefecture Inside Nihon Denso Co., Ltd.

Claims (3)

[Claims] 1. A brazing sheet made of an Al alloy for a heat exchanger which forms a tank portion and a refrigerant passage by joining press-formed brazing sheets by vacuum brazing, wherein the Mn is 0.5 to 2 mm. 0.0 mass%
(Hereinafter simply referred to as%), Cu: 0.1 to 1.0%, M
g: 0.05 to 0.5%, Ti: 0 to 0.3%, the balance being an Al alloy core material consisting of Al and unavoidable impurities, and an Al-Si-Mg alloy brazing material on both surfaces thereof 5
ク ラ ッ ド 20% of the cladding ratio, and further, M
n: 0.5 to 2.0%, Mg: 0.05 to 0.5%, T
i: an Al alloy containing 0 to 0.3%, the balance being Al and unavoidable impurities, and having an intermediate layer having a thickness of 30 μm or more and a cladding rate of 35% or less. Al alloy brazing sheet. 2. An Al alloy brazing sheet according to claim 1, further comprising an intermediate layer having a thickness of 80 μm or more and a clad ratio of 35% or less. 3. The brazing sheet made of Al alloy according to claim 1, wherein the Al—Si—Mg alloy brazing material further contains Sn 0.05 to 0.5%.