JPH0686641B2 - Aluminum alloy for fin material of heat exchanger, which has excellent thermal conductivity after brazing and sacrificial anode effect - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to an aluminum alloy for a fin material of a heat exchanger in which a fin and a working fluid passage constituent material are joined by brazing such as a radiator and a car air conditioner. In particular, the present invention relates to an aluminum alloy for a fin material, which has a high thermal conductivity after brazing and has an excellent sacrificial anode effect.

[Prior Art] In radiators of automobiles, air conditioners, heat exchangers such as intercoolers and oil coolers, working fluid passage configurations such as Al-Cu alloys, Al-Mn alloys, and Al-Mn-Cu alloys. The material and the aluminum alloy fin material are assembled by brazing. Further, the fin material is required to have a sacrificial anode effect in order to prevent corrosion of the working fluid passage constituent material, and also has an excellent high temperature buckling resistance so as not to be deformed by high temperature heating during brazing or the brazing material does not corrode. Sex is required. The addition of Mn is effective in preventing deformation during brazing and corrosion of the brazing material.
Al-Mn alloys such as alloys are used. Then, in order to impart a sacrificial anode effect, Zn, Sn, In, Al, Mn alloy,
The method of making electrochemically base by adding such as (see, for example, JP-A-62-120455), in order to further improve the high temperature buckling resistance (high temperature sag resistance), Cr, Ti, Zr
A method of adding such a compound has been proposed (see, for example, Japanese Patent Application Laid-Open No. 50-118919).

[Problems to be Solved by the Invention] In recent years, there have been strong demands for weighing heat exchangers, reducing costs, and the like. It is necessary to reduce the material thickness). However, when the fin material is made thin, the heat transfer cross-sectional area becomes small, which causes a problem of impairing the heat exchange performance.

In order to solve this problem, it is effective to increase the thermal conductivity of the fin material after brazing, but in the case of Al-Mn based alloy, Mn is a solid solution at high temperature during brazing, so the thermal conductivity The degree of decrease is remarkable. In order to improve the thermal conductivity, pure aluminum (1050, 1070, etc.) is Zn, Sn, In or C.
Attempts have also been made to use fin materials to which r, Ti, Zr, etc. have been added, but in this case, fin collapse is likely to occur due to the low thermal strength after brazing, which is the root cause of the problem. Not a solution.

The present invention is intended to solve this point fundamentally.

[Means for Solving the Problems] The present inventors have studied various aluminum alloys, and compared with conventional Al-Mn-based alloys, the thermal conductivity without significantly lowering the strength after brazing. Greatly improved,
The present invention has been completed by finding an aluminum alloy for fin materials which is excellent in sacrificial anode effect and high temperature buckling resistance.

That is, the present invention, Fe: 1.2 ~ 1.8%, Zr: 0.05 ~ 0.20%
In: 0.005-0.1%, Ga: 0.01-0.2% and Bi: 0.01-0.1%, one or more or two or more Zr: 2% or less, Cu: 0.3%, one or two. Contains seeds,
An aluminum alloy for a fin material of a heat exchanger, which is excellent in thermal conductivity after brazing and sacrificial anode effect, characterized by comprising the balance Al and unavoidable impurities.

The reasons for limiting each component in the present invention are as follows.

Fe: Fe improves the strength of the alloy, that is, the strength of the fin material before brazing and the strength after brazing. Since the alloy of the present invention does not contain Mn, 1.2% or more of Fe is necessary for improving the strength. The more Fe, the higher the strength, 10%
The above is desirable. On the other hand, if it exceeds 1.8%, coarse crystallized substances are generated during casting, making it difficult to manufacture a plate material.

Zr: Zr improves high temperature buckling resistance. If it is less than the lower limit, the effect is not sufficient, and if it exceeds the upper limit, the thermal conductivity after brazing decreases.

In, Ga, Bi: Bases the potential of the fin material and imparts a sacrificial anode effect. If it is less than the lower limit, the effect is not sufficient, and if it exceeds the upper limit, not only the effect is saturated, but also self-corrosion resistance and rolling workability are deteriorated.

Zn: Zn makes the potential of the fin material base and further enhances the sacrificial anode effect. However, when vacuum brazing is applied, Zn evaporates during brazing and the amount of residual Zn decreases, so I
It is necessary to coexist with n, Ga and Bi. If the upper limit is exceeded, the self-corrosion resistance will deteriorate, and the amount of evaporation during vacuum brazing will increase, and the number of times the brazing furnace will be cleaned will increase.

Cu: Improves the strength of the fin after brazing. When the upper limit is exceeded, the potential becomes noble and the sacrificial anode effect is impaired.

Other elements may include Si, Mn, Mg, Cr, Ti, etc. within a range that does not impair the effects of the alloy of the present invention. However,
In both cases, the thermal conductivity decreases as the content increases, so
Si less than 0.6%, Mn less than 0.1%, Mg less than 0.2%, Cr less than
It is desirable that 0.05% or less and Ti be 0.05% or less. Mg
When reacting with fluoride flux brazing, it reacts with the flux, so it is desirable to keep it lower, that is, 0.1% or less. Ti may be added as an alloying element for refining the crystal during casting or as an Al-Ti-B refining agent, but it is preferable to keep it within the above range.

[Example] Twenty-two alloys shown in Table 1 were melted and cast, homogenized,
Hot rolling, cold rolling, intermediate annealing and finish cold rolling were performed to obtain a fin material having a thickness of 0.07 mm. In addition, Mn as an impurity was 0.05% or less in the case where the amount of Mn was not described. Then, after heating at 600 ° C for 3 minutes in a vacuum of 5 × 10 ^-5 Torr or less as in the brazing, tensile test and electrical conductivity measurement were performed, and 3% NaCl aqueous solution adjusted to pH 3 was used. After being immersed in the solution for 1 hour, the natural electrode potential was measured. In general, the thermal conductivity and the electrical conductivity of a metal are in a proportional relationship, so here, the electrical conductivity (at 25 ° C.) is measured instead of the thermal conductivity.

Further, the fin material was corrugated, placed on a plate material having 3003 as a core material and 4004 as a skin material (brazing material), and vacuum brazing was performed to examine the brazing property. Then, the CASS test (JIS
D0201) was carried out for one month, the maximum corrosion depth of the plate was investigated, and the corrosion state of the fin was observed.

The results are also shown in Table 1.

Inventive Examples No. 1 to 10 have a high tensile strength of 8.2 kgf / mm ² or more,
It also has a high electrical conductivity of over 50%. Also, the brazing property is good, and the natural electrode potential is -840 mV ^VS SCE or less, which is base,
The maximum corrosion depth of the plate material is as small as 0.03 to 0.05mm, and it has excellent sacrificial anode effect. Comparative Example No. 11 has a small amount of Fe and thus has a low tensile strength. No. 12 has a small amount of Zr, so the brazing material is eroded in the fin material during brazing and the fins buckle. No. 13 has a large amount of Zr and thus has low electric conductivity. No. 14 has a noble natural electrode potential of -720 mV ^VS SCE because it does not contain In, Ga, and Bi, the maximum corrosion depth of the plate material is large at 0.46 mm, and the sacrificial anode effect is not sufficient. No.15
Nos. 18 to 18 have a large amount of In, Ga, Bi or Zn, so that the self-corrosion resistance of the fin material is inferior and the wear of the fin is remarkable.

No. 19 has a large natural electrode potential of -710 mV ^VS SCE due to the large amount of Cu, and the maximum corrosion depth of the plate material is 0.43 mm larger.

Since Comparative Example 20 has a large amount of Mn as an impurity, it has a low electric conductivity of 45% IACS.

Comparative example No. 21 is M, which has been used as a conventional fin material.
This is the case for the 3003 alloy with n and Cu added, and the electrical conductivity is 3
It has a low 7% IACS and low thermal conductivity. In addition, the natural electrode potential is noble at -700 mV ^VS SCE, and the maximum corrosion depth of the plate material is large at 0.45 mm, so the sacrificial anode effect is not sufficient.
No. 22 is a 3203 alloy to which In, Ga, and Zn are added, but it has a low electric conductivity of 37% IACS and a low thermal conductivity.

[Advantages of the Invention] According to the present invention, a fin material having excellent thermal conductivity, sacrificial anode effect, high temperature buckling resistance, and strength can be provided, the fin material can be thinned, and the heat exchanger can be quantified. Contributes to cost reduction.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kenshi Kato 3-12-12, Chiennen, Minato-ku, Nagoya, Aichi Sumitomo Light Metal Industries, Ltd. Technical Research Laboratory (56) References JP 61-195947 (JP, A) ) JP-A-55-95094 (JP, A) JP-A-61-217547 (JP, A) JP-A-54-124811 (JP, A) JP-A-55-119146 (JP, A) JP-A-59- 100249 (JP, A) JP-A-56-13456 (JP, A)

Claims (4)

[Claims] 1. Fe: 1.2 to 1.8% (weight%, the same applies hereinafter), Zr:
0.05 to 0.20%, In: 0.005 to 0.1%, Ga: 0.
01 to 0.2% and Bi: 0.01 to 0.1% of one or more kinds are contained, and the balance is Al and inevitable impurities,
Particularly, Mn is 0.1% or less, which is an aluminum alloy for fin material of a heat exchanger, which has excellent thermal conductivity after brazing and sacrificial anode effect. 2. Fe: 1.2 to 1.8%, Zr: 0.05 to 0.20%, Zn: 2%
Contains: In: 0.005-0.1%, Ga: 0.01-0.2
% And Bi: 0.01 to 0.1%, one or more of them are contained, and the balance is Al and unavoidable impurities. In particular, Mn is
An aluminum alloy for a heat exchanger fin material, which has a thermal conductivity after brazing and a sacrificial anode effect, which is 0.1% or less. 3. Fe: 1.2 to 1.8%, Zr: 0.05 to 0.20%, Cu: 0.3
% Or less, In: 0.005-0.1%, Ga: 0.01-0.
2% and Bi: 0.01 to 0.1% of 1 or 2 or more types, and the balance Al and unavoidable impurities.
An aluminum alloy for a heat exchanger fin material, which is excellent in thermal conductivity after brazing and sacrificial anode effect, characterized by being 0.1% or less. 4. Fe: 1.2 to 1.8%, Zr: 0.05 to 0.20%, Zr: 2%
Below, containing Cu: 0.3% or less, further In: 0.005-0.1
%, Ga: 0.01 to 0.2% and Bi: 0.01 to 0.1%, and one or more of them, and the balance Al and unavoidable impurities, especially Mn is 0.1% or less. Aluminum alloy for heat exchanger fin material, which has excellent thermal conductivity after attachment and sacrificial anode effect.