JPH07116543B2 - High strength and corrosion resistant aluminum alloy clad material for heat exchanger - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a manufacturing member for manufacturing an Al heat exchanger such as a radiator or a heater core by brazing using a fluoride flux in an inert gas atmosphere. Suitable for use as a tube material or header plate material,
The present invention relates to an Al alloy clad material having good brazing property and having high strength and high corrosion resistance after brazing, and is particularly suitable for a tube material used with a thin wall.

[Prior Art] Tube materials such as automobile radiators and heater cores and header plate materials are made of Al-Mn alloy such as 3003 as the core material, and Al-Si alloy brazing material on one side and other one side. Al-
A three-layer clad material in which a sacrificial anode material such as a Zn-based alloy or an Al-Zn-Mg-based alloy is clad is used. The Al-Si type brazing material is used for joining the tube to the fin and joining the tube to the header plate. Brazing is often performed using a fluoride flux in an inert gas atmosphere. The other side clad with the sacrificial anode material becomes an inner side (water side) during use, and exhibits a sacrificial anode function to prevent pitting and crevice corrosion of the core material.

In recent years, there has been a strong demand for weight reduction of radiators and heater cores, and it has become necessary to reduce the thickness of tube materials and header plate materials. For that purpose, it is necessary to increase the strength of the material, especially the strength after brazing, and in order to increase the strength, Mg is often added to the core material. However, since Mg diffuses to the surface during brazing and reacts with the fluoride flux, a cotton-like product (fluoride of Mg) is produced and adheres, or a bonding failure occurs. Thus
The amount of Mg added to the core material is 0.5% at the maximum, 0.2 for practical use
It is limited to 0.3%, which hinders high strength.

The strength of the tube material and header plate material may also be improved by adding Mg to the sacrificial anode material.

There have been some proposals for the clad material in which Mg is added to the sacrificial anode material.

That is, a method of adding Mg and Zn to the sacrificial anode material of the radiator header plate material or tube material (Japanese Patent Publication No. 63-28704), a method of adding Zn and Mg (Japanese Patent Publication No. 61-89498), A method of simultaneously adding Sn and Mg (JP-A-56-16646, JP-A-63-89641) and a method of adding Mg and Zn to a relatively high concentration (JP-B-62-62).
−45301), has been proposed.

However, the addition of Mg above and 1.1% or 1.5
% Or less, it is added to prevent pitting and crevice corrosion, and strength cannot be improved.

The above Mg addition suppresses the grain boundary diffusion of Sn, the purpose of preventing cracking during hot rolling, the addition of the above Mg is intended to improve the pitting corrosion resistance, both Mg In the case of a high concentration, there is a possibility that it diffuses into the core material and some strength improvement effect is obtained. However, when a thin tube material (cladding material) is made, even if the strength of the core material can be increased by the Mg diffused from the sacrificial anode material, the strength of the sacrificial anode material is Mg.
Addition alone is insufficient, and the strength of the entire clad material cannot be increased. That is, when the thickness is reduced, the contribution to the strength of not only the core material but also the sacrificial anode material is large, and it is necessary to increase the strength of the sacrificial anode material.

[Problems to be Solved by the Invention] The present invention intends to provide a clad material which does not impair the brazing property, that is, which keeps the amount of Mg added to the core material to a maximum of 0.5% and provides high strength after brazing. It is what

[Means for Solving the Problems] The inventors of the present invention investigated a method for obtaining high strength after brazing while keeping the amount of Mg added in the core material at a maximum of 0.5%, and found that the high sacrificial anode material had a high strength. When a concentration of Mg and Si is added, part of the Mg in the sacrificial anode material diffuses into the core material during brazing, strengthening the core material, and the sacrificial anode material itself also contains Mg and Si.
The present invention was completed by finding out that it was strengthened by.

That is, coexistence of Mg and Si in the sacrificial anode material, contributing Mg to strengthen the core material, and strengthening the sacrificial anode material by solid solution strengthening with Mg and Si and age hardening by precipitation of Mg ₂ Si. is there.

That is, in the constitution of the present invention, (1) the core material is Mn: 0.3 to 2.0%, Cu: 0.25 to 0.8%, Si: 0.
2 to less than 0.7%, Mg: containing 0.5% or less, composed of an aluminum alloy consisting of balance Al and unavoidable impurities, the sacrificial anode material compounded on one side of the core material Mg: 1.2 to 2.5%, Si: 0.2
~ 0.8%, Zn: 0.5-2.0%, the balance is composed of an aluminum alloy consisting of Al and unavoidable impurities, and the skin material compounded on the other side of the core material is an Al-Si alloy solder. High strength and high corrosion resistance aluminum alloy clad material for heat exchangers, characterized by being composed of materials, (2) core material is Mn: 0.3 to 2.0%, Cu: 0.25 to 0.8%, Si: 0.
2 to less than 0.7%, Mg: containing 0.5% or less, is composed of an aluminum alloy consisting of the balance Al unavoidable impurities, the sacrificial anode material composite on one surface of the core material Mg: 1.2 ~ 2.5%, Si: 0.2 ~
0.8%, Zn: 0.5-2.0%, In: 0.2% or less,
A skin that contains one or more of Sn: 0.2% or less and Ga: 0.2% or less, is composed of an aluminum alloy consisting of the balance Al and inevitable impurities, and is compounded on the other side of the core material. A high-strength and high-corrosion-resistant aluminum alloy clad material for a heat exchanger, characterized in that the material is a brazing material of an Al-Si alloy.

[Operation] The reasons for limiting the composition and composition range in the present invention will be described.

(1) Core material Mn: Mn improves the strength. Further, the potential of the core material is made noble and the potential difference with the sacrificial anode material is increased to improve the corrosion resistance. 0.3
If it is less than%, the effect is not sufficient, and if it exceeds 2.0%, coarse compounds are generated during casting, and a sound plate material cannot be obtained.

Cu: Cu makes the potential of the core material noble, increases the potential difference between the sacrificial anode material and the brazing material and the core material, and enhances the anticorrosion effect of the sacrificial anode material and the brazing material due to the sacrificial anode effect. Further, Cu in the core material diffuses into the sacrificial anode material and the brazing material during brazing to form a gentle concentration gradient, and the noble potential on the core side, and the surface side of each of the sacrificial anode material and the brazing material are base. A potential is applied, and a gentle potential distribution is formed between them to make the corrosion form a general corrosion type.

Cu in the core material also contributes to the improvement of strength.

The anticorrosion effect and strength improving effect of Cu shown above are
If the Cu content is less than 0.25%, it will not be exhibited. On the other hand, if it exceeds 0.8%, the corrosion resistance of the core material itself will deteriorate and the melting point of the core material will decrease, causing local melting during brazing.

Si: Si improves the strength of the core material. In particular, when coexisting with Mg that diffuses from the sacrificial anode material during brazing, the strength becomes higher due to age hardening after the brazing material. If it is less than 0.2%, the effect is not sufficient, and if it is more than 0.7%, the corrosion resistance is reduced and the melting point of the core material is lowered to cause local melting during brazing.

Mg: Mg has the effect of improving the strength of the core material.

The effect of improving strength is more effectively exhibited by age hardening after brazing when coexisting with Si and / or Cu. However,
If the amount exceeds 0.5%, it reacts with the fluoride flux, hinders the brazing property, and forms Mg fluoride to impair the appearance.

Other elements: Fe, Zn, Cr, Zr and the like may be contained within a range that does not impair the effects of the present invention. However, if Fe is contained in a large amount, the corrosion resistance is impaired, so the Fe content is preferably 0.7% or less. Since Zn makes the potential of the core material base and reduces the potential difference between the sacrificial anode material and the intermediate material, Zn is preferably 0.2% or less.

(2) Sacrificial anode material Mg: Part of Mg in the sacrificial anode material diffuses into the core material mainly during brazing, and improves the strength of the core material together with Si and Cu in the core material. Further, Mg remaining in the sacrificial anode material improves the strength of the sacrificial anode material together with Si. And these effects contribute to the improvement of the strength of the entire clad material. If it is less than 1.2%, the effect is not sufficient, and if it exceeds 2.5%, local melting occurs during brazing.

Although Mg in the sacrificial anode material diffuses to the core material during brazing, it has a concentration distribution as shown in Fig. 1 and diffuses in large amounts to the brazing material side, hindering the brazing property. There is no such thing. Needless to say, diffusion also occurs during the production of the clad, and there is a slight concentration distribution at the boundary between the core material and the sacrificial anode material.

Si: Si improves the strength of the sacrificial anode material and contributes to the strength of the entire clad material. In particular, age hardening occurs together with Mg remaining in the sacrificial anode material, which contributes to the improvement of strength. 0.2
If it is less than%, the effect is not sufficient, and if it exceeds 0.8%, local melting occurs during brazing.

Zn: Zn makes the electric potential of the skin material base and gives a sacrificial anode effect. As a result, the mode of corrosion is changed to the general corrosion type, and pitting corrosion and crevice corrosion are suppressed. If less than 0.5%, the effect is not sufficient, 2.0%
If it exceeds, the self-corrosion resistance is deteriorated and the corrosion rate is increased.

In, Sn, Ga: In, Sn, and Ga all reduce the potential of the skin material to suppress pitting and crevice corrosion. If it exceeds the upper limit, the self-corrosion resistance and rolling processability deteriorate.

Unlike Zn and Mg, these elements do not evaporate in large quantities during brazing or react with the flux, so a large amount remains in the skin material, making the skin material's electric potential surely base. . On the other hand, on the other hand, the action of Zn, which diffuses into the skin material to form a gentle concentration gradient and forms a gentle potential distribution, is small, and therefore the action of making the corrosion form a general corrosion type is slightly inferior. Therefore, in the skin material, one or more of In, Sn, and Ga are allowed to coexist with Zn, and this and 0.25 to 0.8%
By combining with a core material containing Cu, In, Sn, Ga
Pitting and crevice corrosion can be achieved by combining the effect of making the electric potential of the base less, the effect of forming a gentle electric potential distribution of Cu in the Zn and core material, and the effect of making the electric potential of Cu in the core material noble. It can be prevented further.

(3) Brazing material The brazing material is a commonly used Al-Si alloy. Usually 6 to 13
An Al alloy containing% Si is used.

[Examples] The present invention will be specifically described with reference to Examples below.

Prepare ingots of core alloy shown in Table 1 below, sacrificial anode alloy shown in Table 2 and brazing alloy 4047, and homogenize the core alloy and sacrificial anode alloy. went. Then, the alloy for the sacrificial anode material and the alloy for the brazing material were hot-rolled to have a predetermined thickness, and the ingot of the alloy for core material was combined and hot-rolled to obtain a clad material. afterwards,
A plate (H14 agent) having a thickness of 0.25 mm was produced by cold rolling, intermediate annealing and cold rolling. The clad material has a core material of 0.20 m
m, the sacrificial anode material and the brazing material were each 0.025 mm.

The alloy composition of each material and its combination are shown in Table 3.

On the brazing material side of the obtained clad plate material, Al-1.2% Mn-1.5
A 0.10 mm-thick corrugated fin made of a% Zn alloy was put on and brazed in a nitrogen gas using a fluoride flux. The brazing temperature (material temperature) was 600 ° C. After brazing, the bonding state between the plate material and the fin was visually observed, and the melting state of the core material and the sacrificial anode material was examined by the cross-section metallographic structure.

Next, a plate material having a thickness of 0.25 mm was heated as it is (without being brought into contact with the fins) under the same conditions as in the fluoride flux brazing, and then a tensile test and a corrosion test were performed. The method of corrosion test, CASS test for outer surface side (the brazing material side), and 30 days, for the inner surface (sacrificial anode material side) C1 ^- 100 ppm, SO ₄
^2-100 ppm, HCO ₃ ^- 100 ppm, was immersed in an aqueous solution containing Cu ²⁺ 10 ppm, heated to 80 ° C. during -8 hr, then repeat cycle that 16hr left to cool to room temperature, was carried out 3 months .

The above results are summarized in Table 3. In Invention Examples Nos. 1 to 17, the brazing property is good, the tensile strength is as high as 17 kgf / mm ² or more, and the maximum corrosion depth is small.

In the case of Comparative Example No. 18, the tensile strength is low because the sacrificial anode material has a small amount of Mg.

Comparative Example No. 19 has a large amount of Mg, so that local melting occurs during brazing.

Comparative Example No. 20 has low tensile strength because the sacrificial anode material has a small amount of Si.

In Comparative Example No. 21, since the amount of Si is large, local melting occurs during brazing.

In Comparative Example No. 22, since the Zn of the sacrificial anode material is small, the corrosion depth on the inner surface side is slightly large.

On the contrary, No. 23 has a large amount of Zn, so the corrosion depth on the inner surface side is large.

No. 24, 25 and 26 have a large amount of In, Sn or Ga,
Corrosion depth on the inner surface side is large.

No. 27 has a low tensile strength due to a small amount of Mn in the core material.
As for 28, since a large amount of Mn is contained in the core material, a healthy plate material is not obtained.

No. 29 has low tensile strength due to a small amount of Cu in the core material, and has a large corrosion depth on the outer surface side.

No. 30 has a large amount of Cu in the core material, so that melting occurs during brazing.

No. 31 has a low tensile strength because the core material is low in Si.

No. 32 has a large amount of Si in the core material, and therefore melts during brazing.

No. 33 has a low tensile strength because the core material does not contain Mg.

No. 34 has a brazing defect because the core material has a large amount of Mg.

No. 35 has a low tensile strength because the core material is 3003,
The outer surface has a large corrosion depth.

[Effects of the Invention] As described above, the clad material of the present invention has high strength and corrosion resistance as a material for fluoride flux brazing, and
It is an Al heat exchanger clad material with excellent brazing properties. As a result, the tube material and the header plate material can be made thin, and the weight of the radiator and the heater can be reduced.

[Brief description of drawings]

FIG. 1 is a sectional view showing the Mg concentration distribution after brazing of the material of the present invention.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kenji Kato 3-12-12, Minen-ku, Nagoya-shi, Aichi, Sumitomo Light Metal Industries, Ltd. Technical Research Institute (72) Inventor Naoki Tokizo, Minen-ku, Nagoya, Aichi Sumitomo Light Metal Industry Co., Ltd. Technical Research Institute (72) Inventor Keizo Nanba 3-11, Sennen, Chitose, Minato-ku, Nagoya, Aichi Prefecture Sumitomo Light Metal Industrial Co., Ltd. Technical Research Institute (56) References 63-303027 (JP, A) JP-A-54-110909 (JP, A) JP-A-55-119146 (JP, A)

Claims (2)

[Claims] 1. A core material is Mn: 0.3 to 2.0% (weight%, hereinafter the same), Cu: 0.25 to 0.8%, Si: 0.2 to less than 0.7%, Mg: 0.5%
The sacrificial anode material containing the following, composed of an aluminum alloy consisting of the balance Al and unavoidable impurities, and the sacrificial anode material compounded on one surface of the core material: Mg: 1.2 to 2.5%, Si: 0.2 to 0.8%, Zn: 0.5 to 2.0 %
Characterized in that it is composed of an aluminum alloy consisting of balance Al and unavoidable impurities, and the skin material compounded on the other surface of the core material is composed of a brazing material of an Al-Si alloy. High strength and corrosion resistant aluminum alloy clad material for heat exchangers. 2. The core material is Mn: 0.3 to 2.0%, Cu: 0.25 to 0.8
%, Si: 0.2 to less than 0.7%, Mg: 0.5% or less, balance A
l Made of aluminum alloy consisting of inevitable impurities,
The sacrificial anode material compounded on one side of the core material is Mg: 1.2 to 2.5
%, Si: 0.2 to 0.8%, Zn: 0.5 to 2.0%, and I
One or more of n: 0.2% or less, Sn: 0.2% or less and Ga: 0.2% or less, and composed of an aluminum alloy consisting of the balance Al and inevitable impurities, and the other side of the core material. A high-strength and high-corrosion-resistant aluminum alloy clad material for a heat exchanger, characterized in that the skin material composited with is composed of a brazing material of Al-Si alloy.