JP2842667B2 - High strength and high corrosion resistance A1 alloy clad material for A1 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 It is.

[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-based alloy or an Al-Zn-Mg-based 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 amount of Mg added to the core material is practically limited to 0.2-0.3%,
This hinders high strength.

[Problems to be Solved by the Invention] An object of the present invention is to provide a clad material which solves the above-mentioned problems of the prior art by preventing the diffusion of Mg in the core material.

Means for Solving the Problems The present inventors provided an intermediate material between the core material and the brazing material in order to suppress the amount of Mg diffused from the core material and reaching the surface (the brazing material side). Various studies were made on the alloy type and thickness of the intermediate material.

As a result, Mn: 0.1 to 2.0% as an intermediate material,
By using an alloy containing u: 0.5% or less and / or Si: 0.5% or less, and determining the thickness in relation to the Mg amount in the core material, the amount of Mg reaching the surface and reacting with the flux can be reduced. It has been found that they can be suppressed and prevent a decrease in brazing properties. Also, the amount of Cu in the core material is 0.
By increasing the content by 15%, it was found that the corrosion resistance was remarkably improved, thereby completing the present invention.

That is, the composition of the present invention is as follows: Mn: 0.3 to 2.0%, Cu: 0.25
~ 1.0%, Mg: 0.4 ~ 1.0%, Si: 0.1 ~ 1.0%, remaining A
and an Al alloy consisting of unavoidable impurities as a core material. One side of this core material contains Mn: 0.1 to 2.0%, further contains Cu: 0.5% or less and / or Si: 0.5% or less, and the remaining Al and unavoidable impurities. Al-Si alloy brazing material is clad through an Al alloy intermediate material consisting of: Al-Zn alloy and Al-Zn-Mg
4 clad with sacrificial anode material made of any of
In the layer clad material, a relation of T ≧ 58 × {[Mg (%)] − 0.35} ^1/2 is established between the thickness T (μm) of the intermediate material and the Mg amount (%) in the core material, and The amount of Cu (%) in the core material
This is a high-strength, high-corrosion-resistant Al alloy clad material for Al heat exchangers manufactured by fluoride flux brazing, characterized in that the amount is made 0.15% or more larger than the Cu content (%).

Hereinafter, the amounts and functions of the respective components of the above-described material will be described.

(1) Core material 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. 0.3%
If it is less than 2.0%, 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: The potential of the core material is made noble, the potential difference between the sacrificial anode material and the intermediate material and the core material is increased, and the anticorrosive action of the sacrificial anode material and the intermediate material due to the sacrificial anode effect is increased. Furthermore, Cu in the core material
During brazing, it diffuses into the sacrificial anode material and the intermediate material to form a gentle concentration gradient, the core material side has a noble potential, and the surface side of each of the sacrificial anode material and the intermediate material has a low potential, and the middle is gentle A potential distribution is formed to make the corrosion mode a general corrosion type. The anticorrosion effect of Cu as described above is not exhibited unless the Cu content in the core material is larger than the Cu content in the sacrificial anode material or the Cu content in the intermediate material, and in particular, the Cu content in the core material is better. If not more than 0.15%, the concentration gradient after diffusion is too small and the effect is not sufficient. Normally, Cu is not added to the sacrificial anode material, but care must be taken in that case because Cu may be added to the intermediate material for the purpose of improving strength.

 Cu in the core material also contributes to strength improvement.

The anticorrosive action and strength improving effect of Cu shown above are not exhibited when the Cu content in the core material is less than 0.25% by weight, while the Cu content in the core material is 1.0%.
If the temperature exceeds the above range, the corrosion resistance of the core material itself is deteriorated and the melting point of the core material is lowered, so that local melting occurs during brazing.

Mg: improves the strength of the core material. The strength improvement effect is due to Si and / or
Alternatively, when coexisting with Cu, it is more effectively exerted by age hardening after brazing. If it is less than 0.4%, the effect is not sufficient, and 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.

Si: Improves the strength of the core material. The strength improving effect is well exhibited by age hardening after brazing when coexisting with Mg. 0.1%
If it is less than 1.0%, 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.

Other elements: Fe, Zn, Cr, Zr, Ti and the like may be included in 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 it is necessary to make the content 0.7% or less. Zn makes the potential of the core material low and reduces the potential difference between the sacrificial anode material and the intermediate material, so it needs to be 0.2% or less.

(2) Intermediate material Mn: Improves strength. If it is less than 0.1%, 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, Si: These elements contribute to strength improvement. In particular, Mg diffuses from the core material during brazing, so after brazing, Mg and Cu,
Since Si coexists, the strength is improved by age hardening. However, since these elements promote the diffusion of Mg from the core material to the brazing material, the higher the content, the worse the brazing property. Therefore, in order to secure brazing properties
It is necessary to limit Cu to 0.5% or less and Si: 0.5% or less.
Also, as described above, in order to form a gradual concentration gradient of Cu from the core material toward the surface of the intermediate material (brazing side), and to make the corrosion form a complete corrosion type, the amount of Cu in the intermediate material must be It is necessary to reduce the amount of Cu in the material by 0.15% or more.

Other elements: Fe, Ti, Cr, Zr, Zn, etc. 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 it must be 0.7% or less. Also, Zn
May be added to the intermediate material to provide a sacrificial anode effect, in which case 0.3%
Must be:

Thickness: The intermediate material is to suppress the amount of Mg in the core material that diffuses and reaches the brazing material side, and its thickness T (μm) depends on the Mg amount (%) in the core material. Is determined by the following equation.

T ≧ 58 × {[Mg (%)] − 0.35} ^1/2 This equation is obtained by experiment, but as the amount of Mg in the core material increases, the thickness of the intermediate material must be increased. It is shown that. And when the thickness of the intermediate material does not satisfy this equation, that is, 58 × {[Mg (%)] − 0.35}
^If it is less than ^{1/2, the} amount of Mg diffused into the brazing material during brazing is large, and Mg and fluoride flux react to cause poor brazing or fluffy products to be formed, resulting in appearance. Or damage.

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

(4) Sacrificial anode material Clad on the side (inner surface) that comes in contact with water with a radiator or heater core, etc., prevents pitting and crevice corrosion of the core material by the sacrificial anode function. Al-
When a Zn alloy is used and a gap is formed in contact with rubber packing or the like, an Al-Zn-Mg alloy is often used. In each case, an element that lowers the potential, such as In, Sn, Ga, or Bi, may be included.

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

Example 1 An ingot of an alloy for a core material shown in Table 1 below, an alloy for an intermediate material shown in Table 2, an alloy for a brazing material shown in Table 3, and an alloy for a sacrificial anode material shown in Table 4 was prepared. The alloy for the intermediate material, the alloy for the brazing material, and the alloy for the sacrificial anode material were hot-rolled to have a predetermined thickness, and these were combined with the ingot of the alloy for the core material, followed by hot rolling to obtain a clad material. Thereafter, a plate (H14 material) having a thickness of 0.27 mm was produced by cold rolling, intermediate annealing, and cold rolling.

The structure of the clad is 170 μm thick as shown in FIG.
Intermediate material 2 having a thickness of 50 μm on one side of a core material 1 having a thickness of
A layer 3 of brazing material having a thickness of 25 μm is formed.
It has a thickness of 0.27 mm on which a layer of the sacrificial anode material 4 of 25 μm is formed.

The alloy composition of each material and its combination are as shown in Table 5.

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 joining state between the sheet material and the fins, the occurrence state of flocculent products, and the melting state of the core material were examined.

Next, the plate material having a thickness of 0.27 mm was directly heated (without contact with the fins) 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 ₄ for the inner surface (sacrificial anode material side)
^2-100 ppm, HCO ₃ ^- 100 ppm, was immersed in an aqueous solution containing Cu ²⁺ 10 ppm, heated to 80 ° C. for 8 hours, then repeating the cycle that left 16 hours while cooling to room temperature, 3 months went.

The following results are summarized in Table 5. Invention Examples (No. 1,
In the case of No. 3 to 13), the brazing property is good and the tensile strength is 18 kg
High f / mm ² or higher and low maximum corrosion depth.

In the case of Comparative Example (No. 2), the amount of Cu in the core material and the amount of Cu in the intermediate material
Due to the small amount difference of 0.11%, corrosion on the outer surface side is deep.

In the case of No. 14, the tensile strength is low due to the small amount of Mn in the core material, and the outer surface side is deeply corroded. In No.15, a sound board was not obtained because Mn was large in the core material.

No. 16 has a slightly lower tensile strength due to a small amount of Cu in the core material, and has deep corrosion on the outer surface side. No. 17 has a large amount of Cu in the core material and locally melts during brazing, so that the tensile strength is low and the corrosion depth on the outer and inner surfaces is large.

No. 18 has low tensile strength due to low Mg in the core material,
In the case of o.19, brazing defects occurred due to the large amount of Mg in the core material, and the outer surface side was deeply corroded.

No.20 has low tensile strength due to low Si content in the core material,
In o.21, local melting occurs due to a large amount of Si in the core material, the tensile strength is low, and the corrosion on the outer surface side and the inner surface side is deep.

No. 22 is a three-layer clad material with 3003 alloy as the core material and no intermediate material, but has low tensile strength and deep corrosion on the outer and inner surfaces.

No. 23 has a slightly lower tensile strength due to a small amount of Mn in the intermediate material. In No.24, a sound plate was not obtained because of the large amount of Mn in the intermediate material.

In No. 25, a cotton-like product is generated during brazing due to a large amount of Cu in the intermediate material, and the outer surface side is deeply corroded because the amount of Cu in the core material is smaller than the amount of Cu in the intermediate material.

No. 26 has a flocculent product during brazing due to the large amount of Si in the intermediate material.

Example 2 A plate of 0.27 mm was produced in the same manner as in Example 1 by the combination shown in Table 6. Here, the thicknesses of the brazing material and the sacrificial anode material were the same as in Example 1, and the thicknesses of the intermediate material and the core material were variously changed.

The obtained plate was subjected to a brazing test, a tensile test, and a corrosion test in the same manner as in Example 1.

Table 6 shows the results. T ≧ 58 × ｛[Mg (%)] −
Failure to satisfy 0.35｝ ^1/2 causes brazing failure.

FIG. 2 shows the results of the brazing test in Table 6 and the results of the brazing tests Nos. 5 to 8 in Table 5 collectively. It can be seen that if the curve T is above 58 × {[Mg (%)] − 0.35} ^1/2 , the brazing property is good, and if it is below the curve, the brazing property is poor.

[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 configuration of a clad material of the present invention. FIG. 2 is a graph showing the results of a brazing test performed in Example 2. 1 ... core material, 2 ... intermediate material, 3 ... brazing material, 4 ... sacrificial anode material.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI C22C 21/00 C22C 21/00 EF28F 21/08 F28F 21/08 D (72) Inventor Yasunaga Ito Minato-ku, Nagoya-shi, Aichi Sumitomo Light Metal Industry Co., Ltd.Technical Research Laboratory (72) Etika YamamotoEtika Yamamoto 3-1-1, Minato-ku, Minato-ku, Nagoya City, Aichi Prefecture Sumitomo Light Metal Industry Co., Ltd.Nagoya Works (56) References JP-A-2-11291 (JP, A) JP-A-64-40195 (JP, A) JP-A-1-208432 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) C22C 21/00-21/18 F28F 21/08 B32B 15/01 B23K 1 / 00,1 / 19,35 / 28

Claims (1)

(57) [Claims] 1. Mn: 0.3 to 2.0% (% by weight, the same applies hereinafter), Cu:
0.25-1.0%, Mg: 0.4-1.0%, Si: 0.1-1.0%,
Al alloy consisting of remaining Al and unavoidable impurities is used as a core material. One side of this core material contains 0.1 to 2.0% of Mn, further contains 0.5% or less of Cu and / or 0.5% or less of Si, and is inevitable with the remaining Al. An Al-Si alloy brazing material is clad through an Al alloy intermediate material made of impurities, and an Al-Zn alloy and an Al-Zn
-In a four-layer clad material clad with a sacrificial anode material made of any one of Mg-based alloys, T ≧ 58 × ｛[Mg] between the thickness T (μm) of the intermediate material and the amount of Mg (%) in the core material. (%)]-0.35｝ ^1/2 , and the Cu content (%) in the core material is Cu in the intermediate material.
High-strength, high-corrosion-resistant Al alloy clad material for Al heat exchangers manufactured by fluoride flux brazing, characterized in that the amount is 0.15% or more than the amount (%).