JP2933382B2 - High strength and high corrosion resistance aluminum alloy clad material for heat exchanger - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for manufacturing a radiator, a heater core, or the like by brazing using a fluoride flux in an inert gas atmosphere.
Al-alloy clad material with good brazing properties and high strength and high corrosion resistance after brazing, suitable for use as a structural member such as tube material and header plate material when manufacturing heat exchangers And
In particular, it is suitable for a thin tube material.

[Conventional technology] Al-Mn based alloys such as 3003 are used as core materials for tubes and header plate materials such as radiators and heater cores of automobiles. Al
A three-layer clad material in which a sacrificial anode material of a -Zn alloy or an Al-Zn-Mg alloy is clad is used. The Al-Si brazing material is used for joining a tube to a fin and joining a tube to a 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 inside (water side) during use, and exhibits a sacrificial anode effect to prevent pitting and crevice corrosion of the core material.

In recent years, there has been a strong demand for weight reduction of radiators, heater cores, and the like, and thinner tube materials and header plate materials have been required. For that purpose, it is necessary to increase the strength of the material, particularly, the strength after brazing, and Mg is often added to the core material for increasing the strength. However, Mg diffuses to the surface during brazing and reacts with the fluoride flux, so that a flocculent product (fluoride of Mg) is generated and adheres, or a bonding failure occurs. Thus,
The maximum amount of Mg added to the core material is 0.5%, practically 0.2 to
It is limited to 0.3%, which hinders high strength.

The strength of the tube or header plate material may also be improved by adding Mg to the sacrificial anode material. For the clad material with Mg added to the sacrificial anode material,
There have been several proposals.

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

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

The addition of Mg is intended to suppress grain boundary diffusion of Sn and to prevent cracking during hot rolling, and the addition of Mg is intended to improve pitting corrosion resistance. In the case of a high concentration, it may be diffused into the core material and a certain degree of strength improving effect may be obtained. However, when a thin tube material (cladding material) is made, the strength of the core material can be increased by Mg diffused from the sacrificial anode material, but 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 increases, and it is necessary to increase the strength of the sacrificial anode material.

[Problems to be Solved by the Invention] Therefore, the present invention provides a clad material that can obtain high strength after brazing without impairing brazing properties, that is, while keeping the amount of Mg added to the core material at a maximum of 0.5%. It is something to offer.

[Means for Solving the Problems] The present inventors studied a method of obtaining high strength after brazing while keeping the amount of Mg added to the core material at a maximum of 0.5%. By adding Mg and Si in concentrations,
Part of the Mg in the sacrificial anode material diffuses into the core material during brazing, strengthening the core material.
And completed the present invention.

That is, Mg and Si coexist in the sacrificial anode material, and Mg contributes to strengthening of the core material, and the sacrificial anode material is strengthened by solid solution effect by Mg and Si and age hardening by precipitation of Mg ₂ Si. is there.

That is, the constitution of the present invention is as follows: (1) The core material is Mn: 0.3 to 2.0%, Cu: 0.25 to 0.8%, Si: 0.2 to 0.8%.
A sacrificial anode material containing 2 to 1.0%, Mg: 0.5% or less, Ti: 0.35% or less, the balance being made of an aluminum alloy composed of Al and unavoidable impurities, and having a composite of Mg: 1.2 to 1 surface of the core material 2.
5%, Si: 0.2-0.8%, Zn: 0.5-2.0%, balance Al
And an aluminum alloy consisting of unavoidable impurities,
A high-strength and high-corrosion-resistant aluminum alloy clad material for a heat exchanger, wherein the skin material combined with the other surface of the core material is made of an Al-Si alloy brazing material; But, Mn: 0.3-2.0%, Cu: 0.25-0.8%, Si: 0.
The sacrificial anode material containing 2 to 1.0%, Mg: 0.5% or less, Ti: 0.35% or less, the balance being made of an aluminum alloy composed of Al and unavoidable impurities, and having one side of the core material combined with Mg: 1.2 to 2.
5%, Si: 0.2-0.8%, Zn: 0.5-2.0%.
n: 0.2% or less, Sn: 0.2% or less, and Ga: 0.2% or less, containing one or more kinds, the balance being made of an aluminum alloy consisting of Al and unavoidable impurities, and A high-strength corrosion-resistant aluminum alloy clad material for a heat exchanger, wherein a skin material composited on one side is made of an Al-Si alloy brazing material.

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

(1) Core material Mn: Mn improves strength. Further, the potential of the core material is made noble to increase the potential difference from the sacrificial anode material, thereby improving the corrosion resistance. 0.
If it is less than 3%, the effect is not sufficient, and if it exceeds 2.0%, a coarse compound is formed at the time of 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 increases 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 core material side has a noble potential,
The surface side of each of the sacrificial anode material and the brazing material has a low potential,
In the meantime, a gentle potential distribution is formed to make the form of corrosion a general corrosion type.

 Cu in the core material also contributes to strength improvement.

The anticorrosive action and strength improvement effect of Cu shown above are not exhibited when the Cu content in the core material is less than 0.25%, while when it exceeds 0.8%, the corrosion resistance of the core material itself deteriorates and the melting point of the core material decreases. As a result, melting occurs locally during brazing.

Si: Si improves the strength of the core material. In particular, by coexisting with Mg diffused from the sacrificial anode material during brazing, the strength is further increased by age hardening after brazing. If it is less than 0.2%, the effect is not sufficient. If it exceeds 1.0%, the corrosion resistance is reduced and the melting point of the core material is lowered, so that local melting occurs during brazing.

Mg: Mg has the effect of improving the strength of the core material, but deteriorates the brazing properties. Therefore, the Mg content in the core material needs to be 0.5% or less. If it exceeds 0.5%, it reacts with the fluoride flux to inhibit brazing properties, or Mg fluoride is generated to deteriorate the appearance of the brazed portion.

Ti: Ti further improves the corrosion resistance of the core material. That is, Ti
Is divided into high-concentration areas and low-concentration areas, which are alternately distributed in the thickness direction to form a layer, and the low-Ti area preferentially corrodes compared to the high-concentration areas, thereby forming a corroded form. . As a result, erosion resistance of the material is improved by preventing the progress of corrosion in the thickness direction. If it exceeds 0.35%, a coarse compound is formed at the time of casting, and a sound plate cannot be obtained.

Other elements: Fe, Zn, Cr, Zr, and the like may be included in a range that does not impair the effects of the present invention. However, since Fe impairs corrosion resistance when contained in a large amount, it is preferable to set the content to 0.7% or less. Since Zn makes the potential of the core material low and reduces the potential difference between the sacrificial anode material and the brazing material, it is preferable that Zn be 0.2% or less.

(2) Sacrificial anode material Mg: A part of Mg in the sacrificial anode material mainly diffuses into the core material during brazing, and improves the core material strength together with Si and Cu in the core material. Mg remaining in the sacrificial anode material together with Si improves the strength of the sacrificial anode material. These actions contribute to improving 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, which is not preferable.

During the brazing, Mg in the sacrificial anode material diffuses into the core material, but has a concentration distribution as shown in FIG. 1 and diffuses in large quantities toward the brazing material side, impairing brazing properties. I will not do it. In addition, it goes without saying that diffusion occurs during the production of the clad, and that the boundary between the core material and the sacrificial anode material has a slight concentration distribution.

Si: Si improves the strength of the sacrificial anode material and contributes to the strength improvement of the entire clad material. In particular, the Mg remaining in the sacrificial anode material
At the same time, age hardening occurs to contribute to strength improvement. 0.
If it is less than 2%, the effect is not sufficient, and if it exceeds 0.8%, local melting occurs during brazing.

Zn: Zn lowers the potential of the skin material and provides a sacrificial anode effect.
As a result, the mode of corrosion is changed to a general corrosion type to suppress pitting and crevice corrosion. If less than 0.5%, the effect is not sufficient.
%, The self-corrosion resistance deteriorates and the corrosion strength increases.

In, Sn, Ga: In, Sn, and Ga all make the potential of the skin material low and suppress pitting and crevice corrosion. If the upper limit is exceeded, the self-corrosion resistance and rolling workability deteriorate.

Since these elements do not evaporate in large quantities during brazing or react with flux like Zn and Mg,
It remains in the skin material and ensures that the potential of the skin material is low. However, on the other hand, the effect of diffusing into a skin material like Zn to form a gentle concentration gradient and forming a gentle potential distribution is small, and therefore, the effect of making the corrosion mode entirely corrosive is inferior. Therefore, in the skin material, Zn is allowed to coexist with one or more of In, Sn, and Ga, and this is combined with a core material containing 0.25 to 0.8% of Cu to lower the potential of In, Sn, and Ga. , A function of forming a gentle potential distribution of Zn and Cu in the core material, and a function of making the potential of Cu in the core material noble, are combined to further prevent pitting and crevice corrosion.

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

[Examples] Hereinafter, the present invention will be specifically described with reference to Examples.

Ingots of the alloy for the core material shown in Table 1 below, the alloy for the sacrificial anode material shown in Table 2 and the alloy for the brazing material 4045 were prepared, and the alloy for the core material and the alloy for the sacrificial anode material were homogenized. went. Then, the alloy for the sacrificial anode material and the alloy metal for the brazing material were formed to a predetermined thickness by hot rolling, and these were combined with the ingot of the alloy for the core material to obtain a clad material by hot rolling. Then, cold rolling, intermediate annealing, cold rolling to thickness
A 0.25 mm plate (H14 material) was produced. The configuration of the clad material was 0.20 mm for the core material and 0.025 mm for each of the sacrificial anode material and the brazing material.

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

On the brazing material side of the obtained clad sheet material, Al-1.2% Mn-
A corrugated fin having a thickness of 0.10 mm made of 1.5% Zn alloy was placed thereon, and brazing was performed using a fluoride flux in nitrogen gas. The brazing temperature (material temperature) was 600 ° C. After the brazing, the bonding state between the plate material and the fins and the generation state of the flocculent product were visually observed, and the melting state of the core material and the sacrificial anode material was examined by the cross-sectional metal structure.

Next, the plate material having a thickness of 0.25 mm was heated as it was (without contact with the fin) under the same conditions as for the fluoride flux brazing, and then a tensile test and a corrosion test were performed. The corrosion test method was as follows: CASS test for the outer surface (brazing material side), 30 days, Cl-100 ppm, SO for the inner surface (sacrificial anode material side)
_{^{4 2- -100ppm, HCO 3 - 100ppm}} , 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, 3 months went.

Table 3 summarizes the above results. Invention Examples No. 1 to 20
In the case of, the brazing property is good, the tensile strength is as high as 17 kgf / mm ² or more, the maximum corrosion depth is 0.10 mm or less on the inner side, and the maximum corrosion depth is
It is as small as 0.11mm or less. The maximum corrosion depth on the inner surface is
No. 1-9 and No. 17 are 0.08-0.10 mm, whereas In, S
n, No. 10 to 16 containing Ga, No. 18 to 20 are 0.05 to 0.06 mm
And has become smaller.

In the case of Comparative Example No. 21, the tensile strength was as low as 15 kgf / mm ² because the amount of Mg in the sacrificial anode material was small.

In Comparative Example No. 22, other tests were stopped because local melting occurred during brazing because of a large amount of Mg.

Comparative Example No. 23 had a low tensile strength of 15 kgf / mm ² because the amount of Si in the sacrificial anode material was small.

In Comparative Example No. 24, other tests were stopped because local melting occurred during brazing because of a large amount of Si.

In the case of Comparative Example No. 25, the corrosion depth on the inner surface side was slightly large at 0.13 mm because Zn in the sacrificial anode material was small.

Conversely, No. 26 has a high corrosion depth on the inner surface of 0.18 m due to the large amount of Zn.
m and big.

Nos. 27, 28 and 29 have a large corrosion depth on the inner surface side of 0.15 to 0.16 mm because of a large amount of In, Sn or Ga.

No.30 has a tensile strength of 15kgf / m due to low Mn of the core material
m ² and lower, No.31 is not healthy plate material obtained for Mn in the core material is large, test was discontinued.

No.32 has a tensile strength of 15kgf / m due to low Cu in the core material
m ² and low corrosion depth of the outer surface is as large as 0.19 mm.

For No.33, other tests were stopped because melting occurred during brazing due to the large amount of Cu in the core material.

No.34 has a tensile strength of 15kgf / m due to low core Si
m ² and low.

For No. 35, other tests were stopped because melting occurred during brazing due to the large amount of Si in the core material.

No.36 has a tensile strength of 15kgf because the core material does not contain Mg
/ mm ² and low.

No. 37 has poor brazing due to the large amount of Mg in the core material.

No. 38 has a slightly large corrosion depth of 0.14 mm on the outer surface side because the core material does not contain Ti.

In No.39, the test was interrupted because a sound plate could not be obtained due to the large amount of Ti in the core material.

No. 40 has a tensile strength of 12 kgf / m because the core material is 3003
m ² and low corrosion depth of the outer surface side is large and 0.21 mm.

[Effect of the Invention] As described above, the clad material of the present invention is a clad material for an Al heat exchanger having high strength, corrosion resistance, and excellent brazing properties as a material for brazing a fluoride flux.
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 the drawings]

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

────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁶ Identification code FI C23F 13/00 C23F 13/00 EF28F 19/06 F28F 19/06 B 21/08 21/08 D (72) Inventor Takeshi Kato Within Sumitomo Light Metal Industry Co., Ltd., Research Institute, Sumitomo Light Metal Industries Co., Ltd. (1-2) Minato-ku, Nagoya City, Aichi Prefecture (72) Inventor Keizo Namba 3-1-112, Minato-ku, Nagoya-shi, Aichi Prefecture Sumitomo Light Metal Industries Co., Ltd. (72) Inventor Kaoru Tsuzuki 1-1-1 Showa-cho, Kariya-shi, Aichi Japan Inside Denso Co., Ltd. (56) References JP-A-2-175093 (JP, A) JP-A-2 129333 (JP, A) JP-A-64-83396 (JP, A) JP-A-54-110909 (JP, A) JP-A-63-303027 (JP, A) JP-A-55-119146 (JP, A) (58) Field surveyed (Int.Cl. ⁶ , DB name) C22C 21/00-21/18 B23K 1 / 19,35 / 22 F28F 19 / 06,21 / 08 B32B 15/01 C23F 13/00

Claims (2)

(57) [Claims] 1. The core material contains Mn: 0.3 to 2.0% (weight%, the same applies hereinafter), Cu: 0.25 to 0.8%, Si: 0.2 to 1.0%, Mg: 0.5% or less, Ti: 0.35% or less. Then, a sacrificial anode material composed of an aluminum alloy consisting of the remainder A1 and unavoidable impurities, and combined on one surface of the core material, contains Mg: 1.2 to 2.5%, Si: 0.2 to 0.8%,
Zn: contains 0.5 to 2.0%, is composed of an aluminum alloy including the balance of Al and unavoidable impurities, and a skin material composited on another side of the core material is composed of an Al-Si alloy brazing material. A high-strength, high-corrosion-resistant aluminum alloy clad material for heat exchangers. 2. A core material comprising: Mn: 0.3 to 2.0%, Cu: 0.25 to 0.8
%, Si: 0.2-1.0%, Mg: 0.5% or less, Ti: 0.35% or less, and is composed of an aluminum alloy composed of the balance A1 and unavoidable impurities, and a sacrificial anode material composited on one surface of the core material. M
g: 1.2 to 2.5%, Si: 0.2 to 0.8%, Zn: 0.5 to 2.0%, In: 0.2% or less, Sn: 0.2% or less, and Ga: 0.2%
A skin material comprising one or more of the following, composed of an aluminum alloy consisting of the balance of Al and inevitable impurities, and a composite material on the other surface of the core material, is a brazing material of an Al-Si alloy. A high-strength, high-corrosion-resistant aluminum alloy clad material for a heat exchanger, comprising: