JP2768393B2 - Aluminum alloy for heat exchanger fin material with excellent strength after brazing and sacrificial anode effect - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aluminum alloy fin material for a heat exchanger, such as a radiator or a car air conditioner, in which a fin and a working fluid passage material are joined by brazing. Degree and strength,
The present invention relates to an aluminum alloy fin material having an excellent sacrificial anode effect.

[0002]

2. Description of the Related Art In heat exchangers such as radiators for automobiles, air conditioners, intercoolers and oil coolers, Al-Cu alloys, Al-Mn alloys, and Al-Mn alloys are known.
A working fluid passage forming material such as a Cu alloy and a fin material of an aluminum alloy are assembled by brazing. The fin material is required to have a sacrificial anode effect in order to prevent corrosion of the material constituting the working fluid passage. Is required. The addition of Mn is effective in preventing deformation during brazing and erosion of the braze.
-A Mn-based alloy is used. In order to impart a sacrificial anode effect, a method of adding Zn, Sn, In, or the like to an Al—Mn alloy to electrochemically make it base (for example, see Japanese Patent Application Laid-Open No. 62-120455) is also known. In order to further improve high-temperature buckling resistance (high-temperature sag resistance), C
r, Ti, Zr, etc.
-118919) has been proposed.

[0003]

In recent years, there has been a strong demand for weight reduction and cost reduction of heat exchangers, and in order to respond to these demands, materials for heat exchangers (such as working fluid passage materials and fins) have been developed. Materials) must be made thinner. However, when the fin material is made thinner, the heat transfer cross-sectional area becomes smaller, which hinders the heat exchange performance, and also causes a problem that the strength and durability of the heat exchanger as a product are reduced.

To solve this problem, it is effective to increase the thermal conductivity and strength of the fin material after brazing. In the case of an Al-Mn alloy, Mn
, Form a solid solution, so that the thermal conductivity is significantly reduced. As a fin material having excellent thermal conductivity, Mn: 0.1 to 0.8%, Z
r: 0.02-0.2% and Si: 0.1-0.8%
Aluminum alloys containing nickel have also been proposed (Japanese Unexamined Patent Publication No.
In this case, since the Mn content is small, the strength after brazing is low and the fins are likely to collapse or deform during use. Further, since the potential of the fin material is not low, the sacrificial anode effect is small. Also, Si: 0.03-0.
3%, Fe: 0.05 to 0.6%, Zr: 0.0
An aluminum alloy containing 1 or 0.4% and one or two kinds of Mn: 0.01 to 0.3% has also been proposed (see JP-A-63-45352). Since the potential of the material is not low, the sacrificial anode effect is small.
Pure aluminum (1050, 10
70, etc.), Zn, Sn, In or Cr, Ti, Z
Attempts have been made to use fin materials to which r has been added, but in this case, the fins are likely to collapse due to low thermal strength but low strength after brazing. is not.

[0005] The present inventors have proposed that Al, Fe-Si-Mn-Mg-based alloy be used as a fin material having high strength after brazing.
An alloy to which Sn, Ga, or the like is added has been proposed (Japanese Patent Application No. 2-248704). There are other similar proposals (JP-A-3-20436). These have made it possible to reduce the thickness to some extent, but it is necessary to further increase the strength after brazing to further reduce the thickness.

An object of the present invention is to solve the above-mentioned problems. By adjusting the components such as Mn and Si, the thermal conductivity and strength after brazing are high, and the sacrificial anode effect is obtained. To provide an excellent aluminum alloy fin material. .

[0007]

Means for Solving the Problems The present inventors have studied various aluminum alloys, produced an Al-Mn-Si-based compound by coexisting Mn and Si, and further converted Fe and Mg. By adding it, it is possible to combine thermal conductivity after brazing and high strength, and further, Zn
It has been found that the addition of C is excellent in the sacrificial anode effect, and the present invention has been completed.

The structure of the present invention based on the above findings is an aluminum alloy for a heat exchanger fin material as described in the claims.

In summary, Mn: more than 1.5% and 2.2% or less, Si: 0.5 to 1.2%, Fe:
0.1~0.6%, Mg: 0.05~ 0.6% , Zn:
0.5 to 2.0%, Zr: 0.25% or less, the balance being Al and an aluminum alloy which is an unavoidable impurity or an aluminum alloy further containing 0.25% or less of Cr in addition to the above components. Aluminum alloy for exchanger fin material. The reasons for limiting each component in the present invention are as follows.

Mn: Mn forms an Al-Mn-Si-based compound by coexisting with Si to improve the strength before brazing and after brazing. It also improves high temperature buckling resistance and moldability. If the content is less than 1.5%, the effect is not sufficient. If the content is more than 2.2%, coarse crystals are formed at the time of casting, making it difficult to produce a sheet material. Degree decreases.

Si: Si forms an Al-Mn-Si-based compound to improve the strength, and also reduces the amount of solid solution of Mn to improve the thermal conductivity. If the content is less than 0.5%, the effect is not sufficient, and if it exceeds 1.2%, the fin material is melted during brazing. Fe: Fe suppresses the solid solution amount of Mn and improves the thermal conductivity after brazing. If it is less than 0.1%, the effect is not sufficient, and if it exceeds 0.6%, coarse crystals of Al-Mn-Fe system are generated at the time of casting, and it becomes difficult to produce a sheet material.

Mg: Mg improves the strength of the fin.
In particular, age coexistence is caused by coexistence with Si, and the strength is improved without substantially lowering the thermal conductivity. 0.
If it is less than 05%, the effect is not sufficient. If it exceeds 0.6 %, the brazing property is impaired. That is, in the case of the fluoride flux brazing, Mg and the flux react with each other to cause poor brazing, and in the case of the vacuum brazing, the evaporation amount of Mg increases and the number of times of cleaning the brazing furnace increases.

Zn: Zn lowers the potential of the fin material and gives a sacrificial anode effect. If it is less than 0.5%, the effect is not sufficient, and if it exceeds 2.0%, the self-corrosion resistance is deteriorated, and when vacuum brazing is applied, the amount of evaporated Zn during brazing increases, and The frequency of furnace cleaning increases.

Zr, Cr: Improves high temperature buckling resistance.
If it exceeds the upper limit, the thermal conductivity after brazing decreases.

[0015]

EXAMPLE Alloys Nos. 1 to 14 shown in Table 1 were melted and cast, and subjected to homogenization treatment, hot rolling, cold rolling, intermediate annealing and finish cold rolling to obtain fins having a thickness of 0.07 mm. Wood was obtained. The temperature of the intermediate annealing was 300 ° C.

[0016]

[Table 1]

[0017]

[Table 2]

Regarding the fin material manufactured as described above,
After applying the fluoride flux, a heat treatment at 600 ° C. for 3 minutes was performed in a nitrogen gas in the same manner as at the time of brazing, and then a tensile test and an electric conductivity were measured. In general, there is a proportional relationship between the thermal conductivity and the electrical conductivity of a metal. Therefore, here, the electrical conductivity (25 ° C.) was measured instead of the thermal conductivity. In addition, in order to evaluate the sacrificial anode effect, the pH was adjusted to 3 to 3
After being immersed in an aqueous solution of NaCl for 8 hours, the natural electrode potential was measured.

The fin material is corrugated,
3003 alloy as core material and 4045 alloy as skin material (brazing material)
Was placed on a plate material (thickness: 0.6 mm) to be subjected to fluoride flux brazing, and brazing properties were examined. Also, for the joint between the fin and the plate, CASS
The test was conducted for one month based on JIS D0201, and the maximum corrosion depth of the plate was measured and the corrosion state of the fin was observed.

The results are shown in Table 2.

[0021]

[Table 3]

[0022]

[Table 4]

The alloys No. 1 and No. 1 of the present invention were used . No. 2 has a high tensile strength of 14 kgf / mm ² or more and an electric conductivity of 4
It is as high as 3% or more (3004 of the conventional material is 39%), indicating that the thermal conductivity is high. Also, the brazing property is good, and the natural electrode potential is -800 to -830 mV vs SC.
It is in the range of E and is electrochemically low. Also, CASS
The maximum corrosion depth of the plate material after the test is 0.10-0.
It is as small as 13 mm and has excellent sacrificial anode effect. In addition, the fins are corroded normally. Further, the productivity of the plate material is good without any problem.

On the other hand, the comparative alloy No. 3 has a low tensile strength due to a small amount of Mn.

In No. 4, since the amount of Mn was small, the productivity of the plate material was poor, and a sound fin material could not be obtained.

No. 5 has a low tensile strength and a low electric conductivity due to a small amount of Si. In No. 6 , local melting occurred during brazing because of the large amount of Si.

No. 7 has a low electric conductivity due to a small amount of Fe. In No. 8, since the amount of Fe was large, the productivity of the plate was poor, and a sound fin material could not be obtained.

No. 9 has a low tensile strength because of a small amount of Mg, and No. 10 has a reaction between flux and Mg due to a large amount of Mg, resulting in poor bonding.

In Nos. 11 and 14, since the amount of Zn is small, the potential of the natural electrode becomes as high as about 3003 alloy, and the maximum corrosion depth of the plate is large. That is, it is inferior to the sacrificial anode effect.

In No. 12, since the amount of Zn is large, the corrosion consumption of the fin is remarkable.

No. 13 has a small electric conductivity because of a large amount of Zr and Cr.

[0032]

According to the present invention, the thermal conductivity after brazing,
A fin material with excellent strength and sacrificial anode effect can be provided,
The fin material can be made thinner, which contributes to the weight reduction and cost reduction of the heat exchanger.

Continued on the front page (72) Inventor Yuji Suzuki 5-11-3 Shimbashi, Minato-ku, Tokyo Sumitomo Light Metal Industries Co., Ltd. (72) Inventor Takeshi Kato 5-11-3 Shimbashi, Minato-ku, Tokyo Sumitomo Light Metal Within Industrial Co., Ltd. (72) Inventor Su Kendo 5-11-3, Shimbashi, Minato-ku, Tokyo Sumitomo Light Metal Industries, Ltd. (56) References JP-A-3-104838 (JP, A) JP-A-3 -20436 (JP, A) JP-A-54-140098 (JP, A)

Claims (2)

(57) [Claims] 1. Mn: more than 1.5% and 2.2% or less, Si: 0.5 to 1.2% Fe: 0.1 to 0.6 % Mg: 0.05 to 0.6 % Zn: 0.5 to 2.0% Zr: 0.25% or less Residual aluminum and unavoidable impurities, an aluminum alloy for a heat exchanger fin material. 2. The aluminum alloy for a heat exchanger fin material according to claim 1, comprising Cr: 0.25% or less.