JP2000008130A - Member for heat exchanger made of aluminum alloy excellent in corrosion resistance - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the corrosion resistance of a heat exchanger by a method other than a corrosion preventing method by using a Zn-contg. fin. SOLUTION: A fin material obtd. by cladding one side or both sides of an aluminum or aluminum alloy core material with an Al-Si series brazing filler metal, and in which the Zn content in the core material and the brazing filler metal is adjusted to <=0.3% and an extruded tube material contg. 0.3 to 1.2% Mn, 0.1 to 1.1% Si, and the balance Al with inevitable impurities are assembled. They are subjected to brazing to obtain a heat exchanger excellent in corrosion resistance. The corrosion resistance of the heat exchanger can be secured without damaging the extrudability of the tube material.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a member for an aluminum alloy heat exchanger suitable for applications requiring corrosion resistance, such as a heat exchanger for a car such as a car cooler.

[0002]

2. Description of the Related Art Extruded tubing used in heat exchangers such as car coolers has a very complicated and fine cross-sectional shape, such as a hollow shape having a plurality of holes, so that the extrudability (the pushing force is small, the extrusion speed is small). The faster, the better the extrudability)
In order to enhance the strength of the AA1050 alloy and to increase the strength, a material in which Mn, Cu, or the like is added in a small amount (about 0.2%) is used. For this reason, the extruded tube material so far has a composition close to what is called pure Al with few added elements. In such a tube, there is a problem that the tube is susceptible to corrosion because its own potential is relatively low. Conventionally, a sacrificial anode fin that is relatively low by containing Zn at 1% or more is used. Thus, the external corrosion resistance of the tube is improved to prevent corrosion.

[0003]

However, when a fin material containing Zn is used, there is a problem that the self-corrosion rate of the fin is increased, the fin itself is corroded early, and the fin is lost. Further, Zn concentrates in the eutectic phase of the brazing during brazing, which forms a joint (fillet) between the fin and the tube after brazing. For this reason, the electric potential of the fillet portion becomes relatively low, and this portion is most likely to be corroded as compared with the fin and the tube. Then, the fins are separated from the tube, for example, because the fillet portion is corroded and lost at an early stage. As a result, the sacrificial anode effect of the fin on the tube does not work, and the tube is corroded at an early stage.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a member for an aluminum alloy heat exchanger which has improved corrosion resistance of a tube without containing Zn in a fin material.

[0005]

Means for Solving the Problems In order to solve the above-mentioned problems, the first invention of the aluminum alloy heat exchanger member having excellent corrosion resistance according to the present invention is an aluminum or aluminum alloy core material having one or both surfaces of Al. A fin material clad with a Si-based brazing material, wherein the Zn content of each of the core material and the brazing material is regulated to 0.3% or less, and Mn: 0.3 to 1.2%; Si: 0.1-
It is characterized by a combination of 1.1% and a balance of Al and an extruded tube material composed of unavoidable impurities.

According to a second aspect of the present invention, there is provided a member for a heat exchanger made of an aluminum alloy having excellent corrosion resistance, wherein the tube material according to the first aspect further comprises Cu: 0.1 to 0.6% Fe: 0.
It is characterized by containing one or two of 1 to 1.1%.

A third aspect of the present invention is a heat exchanger member made of an aluminum alloy having excellent corrosion resistance, wherein the ratio of the content (% by weight) of Mn and Si in the components of the tube material according to the first or second aspect is as follows. Mn / Si = 1.1-4.5.

According to a fourth aspect of the present invention, there is provided an aluminum alloy heat exchanger member having excellent corrosion resistance.
The tube material is characterized by further containing 0.05 to 0.5% of Mg.

According to a fifth aspect of the present invention, there is provided a heat exchanger member made of an aluminum alloy having excellent corrosion resistance.
The composition of the core material of the fin is as follows: Mn: 0.05 to 1.5%, S
i: 0.1 to 1.0%, and Cu: 0.05 to
0.3%, Fe: 0.1 to 1.0%, Zr: 0.01 to
0.20%, Ti: 0.01 to 0.20%, Cr: 0.
01 to 0.20%, V: 1 out of 0.01 to 0.20%
It is characterized in that it contains one or more species and the balance consists of Al and inevitable impurities.

Hereinafter, the reasons for limiting the components in the present invention will be described. (Tube material) Mn: 0.3 to 1.2% Mn crystallizes or precipitates as an intermetallic compound to improve the strength after brazing, and also makes the potential of the tube noble to move the tube relative to the fin. To increase the corrosion resistance of the tube. Mn is S
There is also an action of forming an Al-Mn-Si-based compound with i to improve the strength. To obtain these effects, 0.3%
The above content is necessary, more preferably 0.45% or more, more preferably 0.6% or more. In addition, the said intermetallic compound produced | generated by containing Mn has a problem that the extrudability of a material falls when manufacturing a tube material. A decrease in extrudability not only causes a decrease in productivity, but also causes problems such as an inability to obtain a desired shape and damage to an extrusion die. To solve this problem, the Si
This is avoided by forming an l-Mn-Si-based compound. However, the excessive Mn content cannot prevent the extrudability from being lowered even by the Si content. From this perspective, M
The upper limit of n is 1.2%. Further, for the same reason, it is desirable to further set the upper limit to 1.0%.

Si: 0.1 to 1.1% Si has an effect of forming an Al-Mn-Si-based compound with Mn to significantly improve extrudability. In addition, by forming a solid solution in the matrix or forming an Al-Mn-Si-based compound, it also has an effect of improving the strength after brazing. To obtain these effects, the content of 0.1% or more is required. Further, it is desirable that the content is 0.2% or more, particularly in view of improving the extrudability, and 0.3%
More desirably, it is contained. On the other hand, an excessive Si content lowers the melting point of the alloy to cause melting of the material at the time of brazing, and lowers the extrudability due to the presence of crystallized substances. Therefore, the upper limit is set to 1.1%. For the same reason, it is desirable to set the upper limit to 0.9%.

Further, in order to improve the extrudability by containing Si, the ratio of the content (% by weight) of Mn to Si in the component must be within the range of Mn / Si = 1.1 to 4.5. Therefore, it is desirable to determine the respective contents. here,
When the above ratio is less than 1.1, the amount of Si becomes relatively large as compared with Mn, and there is a problem that the extrudability is reduced by crystallized Si. On the other hand, when the above ratio exceeds 4.5, M
The amount of Si is relatively small compared to the amount of n, and it becomes difficult to sufficiently compensate for the decrease in extrudability due to the Mn content and to ensure good extrudability by the Si content. The Mn / Si ratio is set to 1.5 or more or 3.5 for the same reason as described above.
It is desirable to do the following.

Cu: 0.1-0.6% Fe: 0.1-
1.1% Cu forms a solid solution to improve the strength after brazing, and Fe crystallizes or precipitates as an intermetallic compound to improve the strength after brazing. Further, since Cu makes the potential noble, a large potential difference from the fin can be obtained, and external corrosion resistance is improved. Also,
Fe is an Al-Mn-Fe-based or Al-Mn-Fe
-Forming a Si-based compound to improve extrudability. In order to obtain these effects, one or two of Cu and Fe may be contained as desired. However, in order to obtain a sufficient effect, the content of each of them must be 0.1% or more. 0.2% or more, and preferably 0.3% or more of Fe. On the other hand, excessive Cu and Fe contents cause crystallization on the surface to increase the corrosion rate and reduce the extrudability, so that the upper limit is 0.6% for Cu and 1.1% for Fe. . Further, it is desirable that the upper limit is 0.5% for Cu and 0.7% for Fe.

Mg: 0.05-0.5% Mg has an effect of improving the brazing property by breaking a surface oxide film at the time of vacuum brazing. In order to obtain this effect sufficiently, the content must be 0.05% or more. On the other hand, an excessive content lowers the extrudability, so the upper limit is 0.5%. When atmosphere brazing is performed instead of vacuum brazing, if Mg is contained, this Mg reacts with a flux (particularly, a fluoride-based material) to form a high-melting-point coating and form a brazing film. In atmosphere brazing, it is desirable not to include Mg.

(Core material in fin material) Zn: 0.3% or less Zn in the fin material makes the potential of the fin low and accelerates the corrosion of the fin. Therefore, it is desirable to reduce the content of Zn as much as possible. The Zn content is regulated to 0.3%. For the same reason, it is desirable to further reduce the content to 0.2% or less.

Mn: 0.05 to 1.5% Usually, pure aluminum or Al-Mn is used for the fin material.
Although a system alloy is used, an Al-Mn system alloy containing 0.05 to 1.5% of Mn can be exemplified. The inclusion of Mn causes the intermetallic compound to crystallize or precipitate out, thereby improving the strength of the fin after brazing. For that purpose, the content must be 0.05% or more. On the other hand, if Mn is excessively contained, the potential becomes noble and the external corrosion resistance of the tube is reduced. Therefore, the upper limit of the Mn content is set to 1.5. For the same reason as above, it is desirable to set the lower limit to 0.2% and the upper limit to 1.2%.

Si: 0.1-1.0% Since Mn forms an Al-Mn-Si compound between 0.1% and 1.0% Mn, and solid-dissolves in a matrix to improve the strength.
If necessary, it is contained together with Mn. In order to obtain these effects, a content of 0.1% or more is required. On the other hand, if the content is excessive, the melting point is reduced and the material is susceptible to erosion by brazing, and the potential becomes noble to reduce the external corrosion resistance of the tube. Therefore, the upper limit is made 1.0%. For the same reason, it is desirable to set the lower limit to 0.3% and the upper limit to 0.8%.

Cu: 0.05-0.3%, Fe: 0.1
~ 1.0%, Zr: 0.01 ~ 0.20%, Ti: 0.
01 to 0.20%, Cr: 0.01 to 0.20%, V:
0.01 to 0.20% Further, the fin material of the Al-Mn alloy may contain one or more selected from the above components. Among these components, Cu is included as a solid solution to improve the strength after brazing. On the other hand, an excessive content lowers the external corrosion resistance of the tube by making the potential noble, so the upper limit is made 0.3%.
For the same reason, the lower limit is 0.1% and the upper limit is 0.2%
It is desirable that Among these components, Fe
Is crystallized or precipitated as an intermetallic compound and improves the strength after brazing. on the other hand,
If an excessive amount of Fe is contained, the rate of self-corrosion becomes too high, so the upper limit is made 1.0%. For the same reason, it is desirable to set the lower limit to 0.2% and the upper limit to 0.8%.
Further, Zr, Ti, Cr, and V are dispersed as fine intermetallic compounds after brazing and have an effect of improving the strength. Therefore, one or more of these elements are optionally contained. In order to obtain this effect sufficiently, the content of each component must be equal to or more than the above lower limit. On the other hand, if each component is contained excessively, the processability is reduced. In the core material of the fin material, it is desirable to adjust the components so that the tube side becomes noble in relation to the tube. That is, Mn, Cu, and Si have the property of making the material noble, and considering their respective contributions, Mn + 2
In the calculation formula of Cu + Si (% by weight), it is preferable that the calculation value of the tube ≧ the calculation value of the core material of the fin.

(Brazing material in fin material) Zn: 0.3% or less Zn in the brazing material is concentrated in the fillet portion at the time of brazing to accelerate the corrosion of the fillet portion, so it is desirable to reduce the content as much as possible. From that viewpoint, Zn as an impurity
The content is set to 0.3% or less. In addition, for the same reason, 0.
It is desirable to set it to 2% or less.

Si: 5 to 13% An Al-Si alloy containing an appropriate amount of Si is used as a brazing material used as a brazing sheet.
A desirable Si content is 5 to 13%. In this content range, the brazing material can be melted and flowed well during brazing, and the members can be reliably joined to each other.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION As described above, the fin material of the present invention includes a brazing sheet in which pure aluminum or an Al--Mn alloy is used as a core material and one or both surfaces of which are clad with an Al--Si brazing material. The Zn content of each material is restricted to 0.3% or less. The regulation of the Zn content can be achieved by carefully selecting raw materials when the above-mentioned materials are melted. Further, the cladding method and the thickness ratio of each material in the above are not particularly limited in the present invention. This brazing sheet is processed into a shape required as a fin, such as a corrugated shape, if necessary, but the shape and processing method are not particularly limited in the present invention.

On the other hand, the above-mentioned components (Al
-Mn-Si alloy), and an aluminum alloy melted by a conventional method can be used. When an extruded material is manufactured using this alloy, 53.
It is preferable to perform a homogenization treatment by heating at 0 ° C. to 600 ° C. for 3 to 15 hours, and then to perform a soaking heat treatment at 450 ° C. to 550 ° C. for 0.1 to 2 hours before extruding. In the homogenization treatment and the soaking treatment, the Al-Mn-Si-based alloy is reliably formed, and as a result, the extrudability of the tube material can be reliably improved. From this viewpoint, the heating temperature of the homogenization treatment is further increased to 550 to
570 ° C., the heating time is preferably limited to 6 to 10 hours, and the heating temperature for the soaking treatment is 480 to 540.
It is desirable to limit the heating time to 0.5 to 1 hour. The heating method and the structure of the heating furnace in the homogenization treatment and the soaking treatment are not particularly limited.
In the above extrusion, it is extruded into an appropriate shape as a tube material.In this extrusion, since the extrudability of the material is good, even when extruding a hollow shape using a porous die, it is efficient and good. Extrusion is also possible. Also, the extrusion method (system) at the time of extrusion is not particularly limited, and an appropriate method can be adopted according to the extrusion shape and the like.

The fin material and the extruded tube material are combined as members for a heat exchanger. In addition,
As long as it is a heat exchanger, its use place and use purpose are not particularly limited, but it is particularly suitable for a heat exchanger for automobiles requiring corrosion resistance, and as a heat exchanger, a condenser, an evaporator, an intercooler And the like. The above-mentioned heat exchanger member is assembled by brazing by attaching both members or a member obtained by adding other members such as a header thereto. The atmosphere, heating temperature, and time for brazing are not particularly limited in the present invention. At the time of brazing, the brazing material in the fin material melts and flows on the surface of the tube material, and is solidified to join the fin material and the tube material. The core material and brazing material in the fin material are Zn
Since the content is regulated, Zn is hardly contained even in the brazing, and a high concentration of Zn is not contained in the fillet formed by brazing. The heat exchanger obtained as described above is efficiently manufactured with good extrudability, has good corrosion resistance, and can be used as a heat exchanger for automobiles in a severely corrosive environment. Demonstrate good durability.

[0024]

EXAMPLE An aluminum alloy having the composition shown in Table 1 was melted and cast according to a conventional method to produce a billet having a diameter of 15 cm, and the billet was subjected to a homogenization treatment of heating at 560 ° C. for 12 hours. 0.8 at 500 ° C
Immediately after performing the soaking process for heating for a time, as shown in FIG. 1, immediately extruded to obtain an extruded tube material 1 having a cross-sectional shape having a plurality of medium passage holes 2 and a thickness of 0.5 mm, At that time, the extrudability was evaluated. The extrudability was evaluated comprehensively based on the extrusion force during extrusion, the extrusion speed, and whether a sufficient shape was obtained. ◎ (very good), ○ (good), Δ (somewhat poor), × (poor) Was evaluated.

Further, an aluminum alloy for a core material and an aluminum alloy for a brazing material having the composition shown in Table 2 are melted and cast by a conventional method, followed by a facing, a homogenizing heat treatment, and hot and cold rolling. The alloy for the brazing was 80 mm thick, and the alloy for the brazing material was a 10 mm thick plate. These are hot-clad rolled so that the brazing alloy is superimposed on both sides of the core alloy, and cold-rolled while appropriately performing intermediate annealing, and temper H14 (final rolling ratio 30%). Thus, a fin material 3 having a thickness of 0.1 mm was produced. This fin material 3 has a fin height of 10 mm
And corrugated so that the fin pitch becomes 5 mm.

The extruded tube material 1 and the fin material 3 are assembled as shown in FIG. 1 by a combination shown in Table 3, and a fluoride-based flux is applied. The extruded tube material 1 and the fin material 3 were brazed and joined for 3 minutes to prepare a heat exchanger (mini-core) for corrosion resistance and strength investigation. The pressure resistance of the heat exchange was evaluated by applying pressure to the inside of the extruded tube material sealed with ion-exchanged water and measuring the pressure at which the tube material began to leak. Further, in order to measure the strength of the extruded tube material, a tensile test was separately performed on the extruded tube material subjected to the heat treatment. The corrosion resistance was evaluated by measuring the pit depth on the tube surface after performing the salt spray test. The salt spray test conditions (continuous spray) were as follows: [test liquid]: 3.5% N
aCl, [Temperature]: Performed continuously at 40 ° C. × 20 days.
Table 3 shows the results of the above evaluations and measurements.

[0027]

[Table 1]

[0028]

[Table 2]

[0029]

[Table 3]

As shown in Table 3, the heat exchanger material obtained by combining the tube material and the fin material of the present invention can be efficiently manufactured in the production (particularly, extrusion) of each member. The obtained heat exchanger had excellent corrosion resistance and pressure resistance, and was excellent in durability. On the other hand, the comparative heat exchanger was inferior in either of the above-mentioned extrudability and corrosion resistance because it deviated from the combination of the present invention.

[0031]

As described above, the aluminum alloy heat exchanger member having excellent corrosion resistance according to the present invention is made of aluminum or aluminum alloy core material having one or both surfaces of Al.
A fin material clad with a Si-based brazing material, wherein the Zn content of each of the core material and the brazing material is regulated to 0.3% or less, and Mn: 0.3 to 1.2%; S
i: Since the extruded tube material containing 0.1 to 1.1% and the balance Al and inevitable impurities was combined, both the fin material and the tube material exhibited good corrosion resistance, and a heat exchanger excellent in durability was obtained. Can be Further, the extrudability of the tube material is good, and the extrusion can be efficiently and favorably performed during the production.

[Brief description of the drawings]

FIG. 1 is a partial perspective view showing an embodiment of the present invention.

[Explanation of symbols]

 1 Extruded tube material 3 Fin material

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Claims (5)

[Claims] 1. A fin material in which an aluminum or aluminum alloy core material is clad on one or both surfaces with an Al-Si brazing material, wherein the core material and the brazing material each have a Zn content of 0.3% or less. Fin material and M
Heat made of an aluminum alloy excellent in corrosion resistance, characterized by combining n: 0.3 to 1.2% and Si: 0.1 to 1.1%, with the balance being Al and an extruded tube material composed of unavoidable impurities. Exchanger components 2. The tube material further comprises Cu: 0.1 to
The member for a heat exchanger made of an aluminum alloy having excellent corrosion resistance according to claim 1, wherein one or two of 0.6% Fe: 0.1 to 1.1% are contained. 3. The method according to claim 1, wherein the ratio of the content (% by weight) of Mn and Si in the components of the tube material is Mn / Si = 1.1 to 4.5. Aluminum alloy heat exchanger components with excellent corrosion resistance 4. The tube material may further contain Mg: 0.05-.
The member for a heat exchanger made of an aluminum alloy excellent in corrosion resistance according to any one of claims 1 to 3, which contains 0.5%. 5. The composition of the fin core material is Mn: 0.05.
~ 1.5%, Si: 0.1 ~ 1.0% and further C
u: 0.05-0.3%, Fe: 0.1-1.0%, Z
r: 0.01 to 0.20%, Ti: 0.01 to 0.20
%, Cr: 0.01-0.20%, V: 0.01-0.
The member for a heat exchanger made of an aluminum alloy having excellent corrosion resistance according to any one of claims 1 to 4, wherein the member comprises one or more of 20% and the balance is Al and inevitable impurities.