JPS5952760B2 - Heat exchanger with a structure with excellent corrosion resistance - Google Patents

Description

Detailed Description of the Invention The present invention relates to an aluminum alloy heat exchanger having a structure with excellent corrosion resistance, and its purpose is to be used as a heat exchanger for car cooler condensers, automobile radiators, etc. In some cases, the sacrificial anode effect of the fin material is intended to protect the plate or tube material serving as the working fluid passage from corrosion.

An air-cooled heat exchanger made of aluminum alloy, which is generally assembled by brazing, includes a passage for a working fluid (refrigerant, cooling water, etc.) and cooling fins on the air side.

In this case, a brazing sheet (with aluminum or corrosion-resistant aluminum alloy as the core material, A1-Si, Al-S
i-Mg,% and further contains MnO. 3-1.5%, M
gO. 2-1%, ZrO. Ol~0.3%, TlO. O
5-0.3%, CrO. Ol~0.3%, FeO. l~
1. A heat exchanger having a structure with excellent corrosion resistance, characterized in that a working fluid passage is constituted by an aluminum alloy extruded shape containing one or more of 1% of aluminum alloy, and a combination of these. 5Sn0.002 to less than 0.02%, Mn
O. 2 to 2%, suppresses Cn to 0.5% or less, and further contains FeO. l~1%, MgO. 2-2%, ZrO. Ol
~0.3%, CrO. Ol~0.3%, TlO. O5~
AlSi, Al-Si-Mg, Al-
The fin material includes a brazing sheet made of Si-Mg-Bi or A1-Si-Bi-Be brazing material as a skin material, and at least CUO. The working fluid passage is composed of an aluminum alloy extruded shape containing 03 to 0.5% and the balance is aluminum and inevitable impurities, and has a structure with excellent corrosion resistance characterized by a combination of these. exchanger.

6Sn0.002 to less than 0.02%, MnO. 2-2%
containing Cn to 0.5% or less, and FeO. l
~1%, MgO. 2-2%, ZrO. Ol~0.3%,
CrO. Ol~0.3%, TlO. Al-Si, Al-Si-Mg, Al-Si-Mg with an aluminum alloy containing one or more of Ol~0.3% as a core material
-The fin material is composed of a brazing sheet made of Bi or Al-Si-Bi-Be based brazing material as a skin material, and CuO. O3 to 0.5%, and further contains MnO. 3
~1.5%, MgO. 2-1%, ZrO. Ol~0.3
%, TiO. O5~0.3%, CrO. Ol~0.3%
, FeO. 1. A heat exchanger having a structure with excellent corrosion resistance, characterized in that a working fluid passage is constituted by an aluminum alloy extruded shape containing one or more of 1% to 1%, and these are combined.

7Sn0.002 to less than 0.02%, MnO. 2-2%
containing Cu, suppressing Cu to 0.5% or less, and further containing ZnO. 2
~1.5%, BIO. Contains at least one kind of OO5 to 0.3%, and FeO. O5~0.3%, MgO
．． 2-2%, ZrO. Ol~0.3%, CrO. Ol~
0.3%, TiO. One or two of O5-0.3%
Al-Si
, Al-Si-Mg, Al-Si-Mg-Bi or Al-Si-Bi-Be brazing material as a skin material, and fin material A1-Si-Mg-B.
It is common that the metal parts are joined by brazing using a laminated plate made of A1-Si-Bi-Be alloy or A1-Si-Bi-Be alloy as a skin material.

However, when these heat exchangers are exposed to a harsh corrosive environment, the materials that make up the working fluid passages become damaged. In the heat exchanger, significant pitting corrosion occurs on the air side, causing leakage of the internal fluid, which has placed many restrictions on the range of use of the heat exchanger.

That is, in the conventional heat exchanger, as shown in FIG.
Since the natural electrode potential of the material 3 becomes more noble than that of the material composing the working fluid passage, the material 3 forming the working fluid passage becomes an anode, and the corrosion current flows from the material 3 forming the working fluid passage to the brazing fillet portion 2 as shown by the arrow. This causes pitting corrosion 4 to occur in the working fluid passage forming material 3.

As a countermeasure against such corrosion, by specifying the composition and combination of the materials forming the working fluid passage and the fins, the air side fin can be used as a sacrificial anode, and the air side surface of the working fluid passage forming material can be protected from corrosion. There is a way to do it.

In this method, as shown in FIG. 2, the fin 1 serves as an anode and the working fluid passage member 3 serves as a cathode similarly to the fillet portion 2, so that corrosion current flows from the fin 1 to the working fluid passage member 3 to the fillet. Flowing like an arrow to part 2,
Although pitting corrosion 5 occurs on the fins 1, the working fluid passage forming material 3
is protected against corrosion, and accidents such as leakage of working fluid can be avoided.
By the way, in recent years aluminum brazing has improved productivity,
From the viewpoint of pollution control, methods that do not use flux in a non-oxidizing atmosphere are increasingly being adopted.

Among them, a fluxless brazing method in a vacuum (about 10 -5 t0rr) environment, called the GE method or vacuum brazing method, has become the mainstream method for brazing aluminum materials at present. However, in this case, the commonly used Al--Zn sacrificial anode material cannot be used because it scatters into the furnace in a vacuum environment due to the high vapor pressure of Zn. Therefore, there is a method of adding an excessive amount of Zn to the fin material in anticipation of scattering, but this is not preferable because it causes significant contamination of the furnace and may reduce brazing properties. It is also possible to add Sn, In, Ga, etc., which do not cause scattering, to the fin core material or brazing material instead of Zn and use it as a sacrificial anode material, but these elements hardly dissolve in solid solution and crystallize. If this happens, even if the amount added is small, cracks will occur during casting and hot rolling, reducing the productivity of the material. The inventors discovered that while maintaining the characteristics as a sacrificial anode material without scattering during brazing,
As a result of research into ways to further improve productivity, we have arrived at the present invention. According to the research conducted by the inventors, a sacrificial anode effect is produced by adding Sn above a certain concentration, but it has been found that cracking during material production also tends to increase with the amount of Sn added.

Materials with an extremely small amount of Sn added that do not cause cracks are
Al-Sn binary alloys do not produce a sacrificial anode, but a ternary alloy containing relatively large amounts of third elements such as Mn, Mg, and Si, which have wide solid solubility limits, can produce a sacrificial anode effect. I found it. Furthermore, it has been found that when an element such as Cu, which has a strong effect of increasing the electrode potential, is added to the material, "microgalvanic cells" are formed in the same material, and the sacrificial anode effect is inhibited. Since this material is the core material of the brazing sheet fin material, it must not only have a sacrificial anode effect but also have good brazing properties and strength after brazing. Therefore, like Zn, a portion of Mg in the third element scatters in the furnace, and conversely, if a large amount remains in the core material, it attracts Si in the brazing metal, which tends to cause brazing defects, and the material after brazing Since it cannot be expected to improve strength, it is difficult to use it other than as a supplementary additive to improve other properties. Si also lowers the melting temperature and cannot be expected to improve strength, so it is difficult to use it as a main additive element.

In the end, it was determined that Mn was the most suitable third element to add. However, like Cu, Mn has a slight tendency to make the electrode potential of the material nobler, so in order to fully exhibit the sacrificial anode effect, there are restrictions on the composition of the material to be protected, that is, the material constituting the working fluid passage. In other words, the working fluid passage material must increase the natural electrode potential of the material without increasing the rate of self-corrosion. Cu is an additive element that achieves this objective, but if Cu is added in excess, there is a risk of intergranular corrosion. The present invention described below has been made based on the knowledge obtained through research on the combination of a fin material brazing sheet having sacrificial anode properties and a working fluid passage constituent material having cathode properties as described above.

That is, 1Sn0.002 to less than 0.02%, MnO
．． Al-Si, Al-Si-Mg, Al
- The fin material includes a brazing sheet made of a Si-Mg-Bi or Al-Si-Bi-Be brazing material as a skin material, and at least CuO. A structure with excellent corrosion resistance characterized in that the working fluid passage is formed by an aluminum alloy extruded shape containing O3 to 0.5% and the balance is aluminum and unavoidable impurities, and these are combined. Heat exchanger with.

2Sn0.002 to less than 0.02%, MnO. 2-2%
Al-Si, Al-Si-Mg, Al-Si-Mg-Bi or A1- A fin material is composed of a brazing sheet made of Si-Bi-Be brazing material as a skin material, and CUO. Contains O3~0.5% and further contains MnO
．． 3-1.5%, MgO. 2-1%, ZrO. Ol〜Σ
0.3%, TlO. O5~0.3%, CrO. Ol
~0.3%, FeO. Two heat exchangers having a structure with excellent corrosion resistance, characterized in that a working fluid passage is constituted by an aluminum alloy extruded shape containing one or more of 1 to 1%, and these are combined. .

3Sn0.002 to less than 0.02%, MnO. 2-2%
ZnO. 2～
1.5%, BIO. The core material is an aluminum alloy containing at least one of OO5-0.3%,
, Al3-Si-Mg, Al-Si-Mg-Bi, or Al-Si-Bi-Be based brazing material is used as the skin material to constitute the fin material, and at least CuO. Aluminum alloy extrusion form 3 containing 03 to 0.5% and the balance consisting of aluminum and inevitable impurities
A heat exchanger having a structure with excellent corrosion resistance, characterized in that a working fluid passage is constituted by a combination of materials.

4Sn0.002 to less than 0.02%, MnO. 2-2%
containing Cu, suppressing Cu to 0.5% or less, and further containing ZnO. 2
~1.54%, BIO. Al-S
i, the fin material is composed of a brazing sheet made of Al-Si-Mg, Al-Si-Mg-Bi or Al-Si-Bi-Be based brazing material as a skin material, and CuO.
O3 to 0.5%, and further contains MnO. 3-1.5%,
MgO. 2-1%, ZrO. Ol~0.3%, TiO.
O5~0. ．． 3%, CrO. Ol~0.3%, FeO.
1. A heat exchanger having a structure with excellent corrosion resistance, characterized in that a working fluid passage is constituted by an aluminum alloy extruded shape containing one or more of 1% to 1%, and these are combined.

5Sn0.002 to less than 0.02%, MnO. 2-2%
containing Cu, suppressing Cu to 0.5% or less, and further containing FeO. l
~1%, MgO. 2-2%, ZrO. Ol~0.3%,
CrO. Ol~0.3%, TlO. A1-Si, Al-Si-Mg, Al-Si-Mg
-The fin material includes a brazing sheet made of Bi or Al-Si-Bi-Be based brazing material as a skin material, and at least CuO. The working fluid passage is composed of an aluminum alloy extruded shape containing 03 to 0.5% and the balance is aluminum and inevitable impurities, and has a structure with excellent corrosion resistance characterized by a combination of these. exchanger.

3Sn0.002 to less than 0.02%, MnO. 2-2%
containing Cu, suppressing Cu to 0.5% or less, and further containing FeO. l
~1%, MgO. 2-2%, ZrO. Ol~0.3%,
CrO. Ol~0.3%, TlO. The core material is an aluminum alloy containing one or more of Ol~0.3%, Al-Si, Al-Si-Mg, Al-Si-Mg.
-The fin material is composed of a brazing sheet made of Bi or Al-Si-Bi-Be based brazing material as a skin material, and CUO. O3 to 0.5%, and further contains MnO. 3
~1.5%, MgO. 2-1%, ZrO. Ol~0.3
%, TlO. O5~0.3%, CrO. Ol~0.3%
, FeO. 1. A heat exchanger having a structure with excellent corrosion resistance, characterized in that a working fluid passage is constituted by an aluminum alloy extruded shape containing one or more of 1% to 1%, and these are combined.

SnO. OO2~less than 0.02%, MnO. 2 to 2%, suppressing Cu to 0.5% or less, and further containing ZnO. 2～
1.5%, BIO. Contains at least one type of OO5 to 0.3%, and FeO. O5~0.3%, MgO. 2
~2%, ZrO. Ol~0.3%, CrO. Ol~0.
3%, TiO. Aluminum alloy containing one or more of O5 to 0.3% is used as a core material, and A1-Si,A
l-Si-Mg, Al-Si-Mg-Bi or Al
- Construct a fin material with a brazing sheet made of Si-Bi-Be based brazing material as a skin material, and at least Cu
O. A working fluid passage is constituted by an aluminum alloy extruded section containing O3 to 0.5%, the balance being aluminum and unavoidable impurities, and these are combined. A heat exchanger having a structure with excellent corrosion resistance.

8Sn0.002 to less than 0.02%, MnO. 2-2%
containing Cu, suppressing Cu to 0.5% or less, and further containing ZnO. 2
~1.5%, BIO. Contains at least one type of OO5 to 0.3%, and FeO. O5~0.3%, MgO
．． 2-2%, ZrO. Ol~0.3%, CrO. Ol~
0.3%, TiO. One or two of O5-0.3%
Al-Si
, Al-Si-Mg, AlSi-Mg-Bi or A
A fin material is constituted by a brazing sheet made of l-Si-Bi-Be based brazing material as a skin material, and CUO. O3
~0.5% and further contains MnO. 3-1.5%, Mg
O. 2-1%, ZrO. Ol~0.3%, TlO. O5
~0.3%, CrO. Ol~0.3%, FeO. l~1
1. A heat exchanger having a structure with excellent corrosion resistance, characterized in that a working fluid passage is constituted by an aluminum alloy extruded shape containing one or more of the following.

The effect of Sn in the core material in the first invention is to make the natural electrode potential of the core material base and serve as a sacrificial anode, and even if it is added in an amount below the lower limit, the effect is insufficient; If added in an amount exceeding 100%, problems in material production may occur, such as cracks during casting and rolling.

Moreover, Mn's main effect is to bring out the effect of Sn added in a small amount, but it also contributes to improving the material strength after brazing.

However, if the amount added is less than the lower limit, such effects will be insufficient, and if it exceeds the upper limit, giant precipitates will be formed and material defects will occur, which is not preferable. The purpose of suppressing Cu is to keep the natural electrode potential of the material low and suppress self-corrosion associated with preventing the generation of mital galvanic cells, and these effects may be insufficient if the Cu content exceeds the upper limit. Become.

The composition of the brazing material for the brazing sheet fin material differs depending on the brazing method, but the present invention is applicable not only to high-vacuum flux-less brazing, but also to low-vacuum flux brazing and inert gas displacement flux-less brazing. It is possible to utilize any known brazing method such as furnace brazing using flux, and is not limited by the various known brazing filler metal compositions. In addition, Cu added to the working fluid passage forming material has the effect of enriching the natural electrode potential of the material and making it more susceptible to the sacrificial anode effect from the fin material.
If the amount added is less than the lower limit, this effect will not be sufficient, and if it exceeds the upper limit, self-corrosion will increase and there is a risk of intergranular corrosion.

Although the first invention provides an aluminum heat exchanger with excellent corrosion resistance, it may be necessary to further improve mechanical properties, plastic workability, and sacrificial anode effect due to design constraints and other factors. Therefore, the above 2nd to 8th
The invention is for such cases.

Mn, Mg, Zr, Ti,
Both Cr and Fe are useful for improving the strength and plastic workability of the material without significantly changing the corrosion characteristics.

If the amount of these elements is less than the lower limit, the effect will not be sufficient, and if Mn or Mg is added in an amount exceeding the upper limit, the extrusion processability will be significantly reduced, which is not preferable. Further, adding Zr, Ti, Cr, and Fe in amounts exceeding the upper limit is not appropriate because giant precipitates are generated, resulting in material defects. Third
Zn and Bi added to the core material of the brazing sheet according to the seventh aspect of the invention have an effect that supplements the effect of Sn, but if the amount is less than the lower limit, the effect is not sufficient. If Zn is added in excess of the upper limit, high vacuum atmosphere brazing (GE method)
This is not preferable as it will cause significant contamination of the furnace. Furthermore, if Bi is added in an amount exceeding the upper limit, cracks will occur during hot rolling, which is not appropriate. Fe, Mg, Zr, Cr, T added to the core material of the brazing sheet according to the fifth and seventh inventions
Both i serve to improve strength and plastic workability without inhibiting sacrificial anode action.

Note that the effect of these additive elements is not sufficient if the amount is less than the lower limit. Furthermore, if Mg is added in an amount exceeding the upper limit, the furnace will become significantly contaminated in high vacuum atmosphere brazing (GE method), which is not preferable. Furthermore, if any of Fe, Zr, Cr, and Ti are added in amounts exceeding their upper limits, giant precipitates will be formed, resulting in material defects, which is not appropriate. Next, examples and test results of the present invention will be described together with comparative examples.

Table 1 shows the chemical components of the core material in the fin brazing sheet of the first invention.

Note that A1-10Si-1.5Mg brazing material was used as the skin material. In the table, A1 to A3 are those of the present invention, and A4 to A6
are comparative examples, and their main component is of course Al. (
Note) Materials with Sn and Mn exceeding the upper limit of the claimed range will cause cracks in the ingot and poor rolling (scratches, rough skin) and cannot be put to practical use, so they have been deleted.

Table 2 shows the chemical components of the working fluid passage forming material of the first invention.

In the table, B1 to B3 are those of the present invention, B4 and B5 are comparative examples, and their main component is, of course, Al. Third
The table shows the results of natural electrode potential measurements and accelerated corrosion tests for heat exchanger cores made by combining the materials in Table 1 and the materials in Table 2 above.

In the table, C1 to C3 indicate products of the present invention, and C4 to C8 indicate comparative products. Table 4 shows the chemical components of the core material of each material that was subjected to the corrosion investigation among the fin brazing sheets of the third to eighth inventions.

Note that Al-10Si-1.5Mg brazing material was used as the skin material. In the table, A7 to Al6 are those of the present invention, and Al7
~A2O are comparative examples, and their main component is of course Al. Table 5 shows the chemical components of each of the working fluid passage constituent materials of the second, sixth, and eighth inventions that were subjected to corrosion investigation.

In the table, B6 to Bl3 are those of the present invention, and B14 to Bl
No. 7 is a comparative example, and the component is, of course, Al.

Table 6 shows the results of brazing properties, natural electrode potential measurements, and accelerated corrosion tests for heat exchanger cores made by combining the materials in Table 4 and the materials in Table 5 above.

In the table, C9 to Cl8 are products of the present invention, and Cl9 to C26 are comparative products. In each of the above examples and comparative examples, the thickness of the material constituting the fluid passage is 1.0 mm, and the thickness of the fin brazing sheet is 0.16 mm (both sides are clad with a cladding ratio of 12% on each side). It is.

The brazing conditions are a temperature of 590-610°C and a time of 3-610°C.
It's 5 minutes. Also, the atmospheric pressure at that time was 10-5t0
It is rr. Further, the thickness of the side frame material was 1.5 mm, and the fins and the working fluid passage constituent members were joined by brazing and then caulked. As described above, according to the present invention, by combining the fin material having a sacrificial anode effect and the material that constitutes the noble working fluid passage having a large difference in potential, the working fluid passage forming member is formed. It becomes possible to improve corrosion resistance, expand the range of use of aluminum alloy heat exchangers, and its usefulness is extremely high.

In addition, as mentioned above, Al is used as the skin material of the brazing sheet.
-6~14%Si (for flux brazing), A1-6~
14%Si-0.3-2%Mg. Al-6~14%Si
-0.3-2% Mg-0.01-0.3% Bi (for vacuum brazing), 0.1% or less Bi, Sr, Ba, Sb, B
The essence of the present invention is not changed even if any brazing filler metal from A1-6 to 14% Si (for inert gas atmosphere brazing) containing e.g. Any of flux brazing, vacuum brazing, or inert gas atmosphere brazing may be used as the attachment method.

By limiting the composition of the fin material and the aluminum alloy of the working fluid passage material, the present invention can obtain an excellent sacrificial anode effect. In addition, the cathode current required for corrosion protection must be supplied.

In order to achieve this purpose, Finpitz has 1001
It is preferable that it is 01 or less. FIG. 3 shows an example of a corrugated fin. Fin Pitch 1 is 1
If it exceeds 0 mm, the cathode current will be insufficient and corrosion protection may not be achieved partially. In the above-mentioned heat exchanger, an extruded shape is generally used as a working fluid passage constituent material, and in order to reduce the size of the heat exchanger, the heat exchanger is often subjected to a serpentine bending process 7 before use.

Figure 4 shows the outline. In that case, the joint 6 between the fin 1 and the working fluid passage member 3 is protected against corrosion due to the sacrificial anode effect of the fin 1, but the serpentine bent portion 7 is located at a distance from the fin 1 that is outside the reach of the anti-corrosion current. ．． Therefore, corrosion protection due to the sacrificial anode effect of the fin 1 cannot be expected.
Therefore, at least ZnO. 2-8%
A recommended method is to use an aluminum alloy containing as the side plate, so that the side plate serves as a sacrificial anode material and protects the serpentine bending part. Note that the purpose can be achieved if an electrical connection (continuity) is established between the side plate and the serpentine bent part, so the two can be joined using normal joining methods such as spot welding, caulking, riveting, and bolting. All you have to do is join them. In addition, even if the side plate itself constitutes a frame, it may also be a plate material, an extruded shape material, a cast material, or a cast material inserted between the frame made of aluminum alloy or steel material and the serpentine bent portion of the working fluid passage component material. It may be any member formed from a lump.

FIG. 5 shows an example in which the side plate 8 is used as a frame. It is assumed that the side plate will be attached after the brazing process, and in order to exhibit a sufficient sacrificial anode effect, at least ZnO
．． It is necessary to contain 2 to 8%.

When the Zn content exceeds the upper limit, it causes a decrease in workability, an increase in the rate of self-corrosion, intergranular corrosion, and layered corrosion, and when used as a frame, it causes a decrease in strength.
Even if it is inserted between the frame and the serpentine bent portion of the working fluid passage component, the corrosion protection period will be shortened, which is inappropriate. Furthermore, depending on the environmental conditions, excessive corrosion protection may occur, accelerating corrosion of the serpentine bending section.
If the Zn content is less than the lower limit, the above effects will not be exhibited.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of the corrosion state of a conventional heat exchanger, Fig. 2 is an explanatory diagram of the sacrificial anode action according to the present invention, Fig. 3 is an explanatory diagram of the fin pitch of a corrugated fin, and Fig. 4 is an explanatory diagram of the working fluid passage. FIG. 5 is an explanatory view of the serpentine bending portion of the constituent material (extruded shape material), and FIG. 5 is an explanatory view of the sacrificial anode side plate frame according to the present invention. 1...Fin, 2...Brazing fillet part, 3...
... Working fluid passage constituent material, 4, 5... Pitting corrosion, 6...
Joint part, 7...廿-Pentine bending part, 8...
Side plate, 1...fin pitch.

Claims (1)

[Claims] 1 Sn 0.002 to less than 0.02%, Mn 0.2 to 2
%, with the balance aluminum containing less than 0.5% Cu, and unavoidable impurities as the core material, Al-Si, Al-Si-Mg, Al-Si-
The fin material consists of a brazing sheet made of Mg-Bi or Al-Si-Bi-Be brazing material, and contains at least 0.03 to 0.5% of Cu, with the balance consisting of aluminum and inevitable impurities. A heat exchanger having a structure with excellent corrosion resistance, characterized in that a working fluid passage is constructed of extruded aluminum alloy sections, and these are combined. 2 Sn0.002~less than 0.02%, Mn0.2~2
%, with the balance aluminum containing less than 0.5% Cu, and unavoidable impurities as the core material, Al-Si, Al-Si-Mg, Al-Si-
The fin material is composed of a brazing sheet made of Mg-Bi or Al-Si-Bi-Be brazing material as a skin material, contains 0.03 to 0.5% of Cu, and further contains Mn0
．． 3-1.5%, Mg0.2-1%, Zr0.01-0
．． 3%, Ti0.05-0.3%, Cr0.01-0.
The working fluid passage is composed of an aluminum alloy extruded shape containing one or more of the following: Heat exchanger with. 3 Sn0.002~less than 0.02%, Mn0.2~2
%, Cu is suppressed to 0.5% or less, and Zn0.
Al-
The fin material includes a brazing sheet made of Si, Al-Si-Mg, Al-Si-Mg-Bi, or Al-Si-Bi-Be brazing material as a skin material, and has at least Cu0.03 to 0.5 A heat exchanger having a structure with excellent corrosion resistance, characterized in that a working fluid passage is constituted by an aluminum alloy extruded section made of % aluminum and unavoidable impurities, and a combination of these. 4 Sn0.002~less than 0.02%, Mn0.2~2
%, Cu is suppressed to 0.5% or less, and Zn0.
Al-
The fin material is composed of a brazing sheet made of Si, Al-Si-Mg, Al-Si-Mg-Bi or Al-Si-Bi-Be based brazing material, and Cu0
．． 03 to 0.5, and at least Cu0.03 to 0
．． 1. A heat exchanger having a structure with excellent corrosion resistance, characterized in that a working fluid passage is constituted by an aluminum alloy extruded shape containing 5% aluminum and the remainder consisting of aluminum and unavoidable impurities, and these are combined. 8 Sn0.002 to less than 0.02%, Mn0.2 to 2
%, Cu is suppressed to 0.5% or less, and Zn0.
2-1.5%, Bi0.005-0.3%, and Fe0.05-0.3%, Mg0
．． 2~2%, Zr0.01~0.3%, Cr0.01~
0.3%, one or two of Ti0.05-0.3%
Al-Si
, the fin material is composed of a brazing sheet made of Al-Si-Mg, Al-Si-Mg-Bi or Al-Si-Bi-Be brazing material as a skin material, and Cu0.0
Contains 3-0.5%, further Mn0.3-1.5%, M
g0.2-1%, Zr0.01-0.3%, Ti0.0
5~0.3%, Cr0.01~0.3%, Fe0.1~
1. A heat exchanger having a structure with excellent corrosion resistance, characterized in that a working fluid passage is constituted by an aluminum alloy extruded shape containing one or more of 1% of aluminum alloy, and a combination of these.