JPH04154931A - Aluminum alloy for fin material in heat exchanger - Google Patents

Abstract

PURPOSE:To obtain an Al alloy for heat exchanger fin material having excellent thermal conductivity, strength, etc., after brazing by preparing the Al alloy containing the specific the specific ratios of Fe, Si, Mg, Zn, Zr, Cr and Mn. CONSTITUTION:The Al alloy containing by wt.% of 0.8-1.8% Fe, 0.1-1.0% Si, 0.05-0.7% Mg, 0.3-2.0% Zn, and if necessary, <=0.3% Cu and further one or more kinds among 0.05-0.25% Zr, 0.05-0.25% Cr, 0.05-0.25% Mn and the balance Al with inevitable impurities is prepared. By this method, the Al alloy for heat exchanger fin material having excellent sacrificial anodic effect is obtd. and can be made to thin in the thickness thereof.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to an aluminum alloy for use as a fin material in a heat exchanger such as a radiator or a car air conditioner, in which the fins and the material forming the working fluid passage are joined by brazing. In particular, the present invention relates to aluminum alloys for fin materials that have high thermal conductivity after brazing and have excellent sacrificial anode effects.

[Prior Art] In heat exchangers such as radiators, air conditioners, intercoolers, and oil coolers for automobiles, working fluid passage structures such as Al-Cu alloys, Al-Mn alloys, and Al-Mn-Cu alloys are used. The material and the aluminum alloy fin material are assembled by brazing. The fin material is required to have a sacrificial anode effect to prevent corrosion of the materials forming the working fluid passage, and brazing sometimes requires an excellent high-temperature resistant seat to prevent deformation due to high-temperature heating and corrosion of the wax. Tropism is required. In brazing, addition of Mn is effective in preventing deformation over time and corrosion of the solder, and Al-Mn alloys such as 3003 and 3203 are used as the fin material. In order to impart a sacrificial anode effect, A
A method of electrochemically making the l-Mn alloy less noble by adding Zn SS n % I n etc. (for example, JP-A-62
-120455 publication), high temperature buckling resistance (see
In order to further improve the high temperature sag resistance), Cr5T
A method of adding iSZr etc. (for example, Japanese Patent Application Laid-open No. 50-11
8919) has been proposed.

[Problems to be Solved by the Invention] In recent years, there has been a strong demand for lighter heat exchangers and lower costs. It is now necessary to make the materials thinner (such as materials). However, when the fin material is made thinner, the heat transfer cross-sectional area becomes smaller, which poses a problem in that heat exchange performance is impaired.

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 alloys, brazing sometimes causes Mn to form a solid solution at high temperatures. Thermal conductivity decreases significantly. As a fin material with excellent thermal conductivity, Mn: 0.1 to 0.8%, Zr: 0
．． 02-0.2% and Hisi: 0.1-0.8%
Aluminum alloys containing
1i3-232 (see iO publication), in this case, due to the small amount of Mn, the strength after brazing is low and the fins tend to collapse or deform during use. Furthermore, since the potential of the fin material is not base, the sacrificial anode effect is small. Also, S i : 0.
03-0.3%, Fe: 0.05-0.6%, zr: 0.01-0.4%, Mn: 0.01
An aluminum alloy containing one or two types of -0.3% has also been proposed (see Japanese Patent Laid-Open No. 83-45352), but in this case, the sacrificial anode effect does not occur because the potential of the fin material is not base. small. Furthermore, pure aluminum (1050, 1070, etc.) with high thermal conductivity, Zn, and Sn.

Attempts have been made to use fin materials with additions of In, Cr5Ti, Zr, etc., but in this case, although the thermal conductivity is high, the strength after brazing is low and the fins tend to collapse, which is the root of the problem. There is no real solution.

In order to solve this problem, the present inventors first conducted the following steps: (1) Fe: 0.8-1.8%, Zr:
0.05-0.20%, Zn: 0.3-2.0
% (Patent Application No. 1-(2) Fe: 0.8
-1.8%, Zr: 0.05-0.20%, further In: 0.005-0.1%, Sn: 0.01
~0.1%, Ga: 0.01-0.2% and B
i; Alloy containing one or more of 0.01 to 0.1% (Japanese Patent Application No. 1-218649) (3) Fe: 0.2 to 1.8%, Si:
0.2-0.8%, Mn: 0.1-0.35%,
Zr: Contains 0.05 to 0.20%, and further contains I
n: 0.005~O,1%, Sn:0, old~0,1
%, Ga: 0. O1-0.2% and B i :
Alloys containing one or more of 0.01 to 0.1% and, if necessary, Zn: 2.0% or less or Cu: 0.3% or less (Patent Application No. 2405
77, Japanese Patent Application No. 1-242319). These alloys have excellent thermal conductivity and sacrificial anode effect after brazing, and also have a certain level of strength after brazing, so they contributed to making the fin material thinner. That is, in the example -, it became possible to reduce the thickness of the conventional fin material of 0.111 mm to 0.08 mm. However, the tensile strength of these fin materials after brazing is 8~1Dkgf/mt.
Since the degree of n is 2, there is a problem in that fins tend to collapse if the thickness is further reduced.

The present invention aims to solve this problem.

[Means for Solving the Problems] The present inventors investigated various aluminum alloys, and by simultaneously adding Si and Mg to an Al-Fe alloy, brazing can improve the subsequent thermal conductivity and high The present invention was completed based on the discovery that it is possible to achieve both strength and strength.

That is, in the present invention, Fe: 0.8 to 1.8%,
Si: 0.1-1.0%, Mg: 0.05-0.
7%, Z n : 0.3 to 2.0%, and further Z
r: 0.05-0.25%, Cr: 0.05
-0.25% and Mn: 0.05-0.25%, and one or more of them, with the balance consisting of Al and inevitable impurities, and the above-mentioned It further contains Cu: 04% or less.

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

Fe: Fe improves the strength of the alloy, ie, the strength before and after brazing.

If it is less than 0.8%, the effect will not be sufficient, and if it exceeds 1.8%, coarse crystallized substances will be formed during casting, making it difficult to manufacture plate materials.

Si: Si improves the strength of the fin. In particular, coexistence with Mg causes age hardening and improves strength without substantially lowering thermal conductivity. Its content is 0.1
If it is less than 1.0%, the effect will not be sufficient, and if it exceeds 1.0%, the fin material will melt during brazing.

Mg: Mg improves the strength of the fin. Especially St.
Coexistence with steel causes age hardening, which improves strength without significantly reducing thermal conductivity. If it is less than 0.05%, the effect is not sufficient. If it exceeds 0.7%, brazing properties will be impaired. That is, in the case of fluoride flux brazing, Mg and flux react to cause poor brazing, and in the case of vacuum brazing, the amount of evaporation of Mg increases, resulting in an increased number of cleanings of the brazing furnace.

Zn: Zn makes the potential of the fin material less noble and provides a sacrificial anode effect. If it is less than the lower limit, the effect will not be sufficient, and if it exceeds the upper limit, self-corrosion resistance will deteriorate, and the amount of evaporation during vacuum brazing will increase, resulting in an increase in the number of cleanings of the brazing furnace.

Zrs Cr, Mn: Increases resistance to wax erosion during brazing. If it is less than the lower limit, the effect will not be sufficient, and if it exceeds the upper limit, the thermal conductivity after brazing will decrease.

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

Other elements may include Ti and the like within a range that does not impair the effects of the light alloy of the present invention. However, as the Ti content increases, the thermal conductivity decreases, so it is desirable to keep it at 0.1% or less.

Ti may be added as an alloying element for grain refinement during casting, or as an Al-Ti-B refiner, but it is desirable to keep it within the above range.

[Example] Alloy Nos. 1 to 21 shown in Table 1 were melted and cast, and subjected to homogenization treatment, hot rolling, cold rolling, intermediate annealing, and final cold rolling to form a 0.07 mm thick fin. I got the material. The temperature of intermediate annealing was 330°C.

Table 1: After applying fluoride flux to the fin material manufactured as described above, the
After heat treatment at 00°C for 3 minutes, a tensile test and electrical conductivity were measured.

Generally, there is a proportional relationship between the thermal conductivity and electrical conductivity of metals, so here we will use electrical conductivity (2
5°C) was measured. In addition, in order to evaluate the sacrificial anode effect, the natural electrode potential was measured after immersion in a 3% NaCl aqueous solution adjusted to pH 3 for 8 hours.

In addition, the fin material is corrugated, placed on a plate material (1.6 mm thick) with 3003 alloy as the core material and 4045 alloy as the skin material (brazing material), and fluoride flux brazing is performed. , the properties of brazing were investigated. Also, a CAS S test was conducted on the joint between the fin and the plate.
The test was carried out for one month in accordance with IS DO201, and the maximum corrosion depth of the plate was measured and the state of corrosion of the fins was observed.

The results are shown in Table 2.

Table 2 = 12 - Invention alloy Nos. 1 to 8 have tensile strength after brazing of 1O
It has a high electrical conductivity of over 49% (compared to 38% for the conventional material 3003).

In addition, brazing properties are good, and the natural electrode potential is -77
It ranges from 0 to 1840+nV vs S CH and is electrochemically base. Further, the maximum corrosion depth of the test material after the CASS test is as small as 0.05 to 0.07 mm, and the sacrificial anode effect is excellent. Furthermore, the corrosion of the fins is also normal.

On the other hand, comparative alloy No. 9 has a low tensile strength due to a small amount of Fen.

In No. IO, a healthy fin material could not be obtained due to the large amount of Fe.

No.]1 has low tensile strength due to the small amount of Si, and N
Since the number o and 12 has a large amount of 5ift, melting occurs during brazing.

No. 13 has low tensile strength (, N
No. 14 has a large amount of Mgff1, so a reaction between the flux and Mg occurs, resulting in poor bonding.

In No. I5, since znffi is small, the natural electrode potential is noble, and the maximum corrosion depth of the plate material is large.

No. IB has a large amount of Zn, so the wear of the fins is significant.

No. 1.7 has a small amount of Zr5Crs and Mn, so corrosion of the wax occurs during brazing.

Nos. 18, 19, and 20 have low electrical conductivity due to large amounts of Zr, Cr, or Mn.

No. 21 has a large amount of Cu, so the natural electrode potential is noble and the maximum corrosion depth of the plate is large.

[Effects of the Invention] According to the present invention, a fin material with excellent thermal conductivity, strength, and sacrificial anode effect after brazing can be provided, and the fin material can be made thinner, thereby reducing the weight of the heat exchanger. Contributes to cost reduction.

Patent applicant: Sumitomo Light Metal Industries, Ltd. Agent Patent Attorney Hidetake Komatsu Agent Patent Attorney Hiroshi Asahi

Claims (2)

[Claims] (1) Fe: 0.8 to 1.8% (weight%, same below)
, Si: 0.1-1.0%, Mg: 0.05-0.7%
, Zn: 0.3 to 2.0%, and further Zr: 0.0
5-0.25%, Cr: 0.05-0.25% and M
An aluminum alloy for heat exchanger fin material, characterized in that it contains one or more of n: 0.05 to 0.25%, and the remainder consists of Al and unavoidable impurities. (2) Fe: 0.8-1.8%, Si: 0.1-1.
0%, Mg: 0.05-0.7%, Zn: 0.3-2.
0%, Cu: 0.3% or less, and Zr: 0.0
5-0.25%, Cr: 0.05-0.25% and M
An aluminum alloy for heat exchanger fin material, characterized in that it contains one or more of n: 0.05 to 0.25%, and the remainder consists of Al and unavoidable impurities.