JPH11199957A - Aluminum alloy composite material for heat exchanger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a composite material capable of lowering the brazing temperature of an aluminum alloy composite material for brazing consisting of a core material and a brazing filler metal and also capable of facilitating the production of the brazing filler metal itself. SOLUTION: One side or both sides of an Al alloy core material having a composition consisting of, by weight, 0.5-2.0% Mn, 1.3-2.5% Cu, and the balance Al with inevitable impurities is clad with an Al alloy brazing filler metal having a composition consisting of, by weight, 7-12% Si, 1-20% Zn, and the balance Al with inevitable impurities.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aluminum alloy composite material coated with a brazing material for brazing, for example, a tube material, a header plate material, a side plate material, etc. constituting a heat exchanger for an automobile. .

[0002]

BACKGROUND OF THE INVENTION Generally,
The heat exchanger member is composed of a composite material called a brazing sheet in which a brazing material is clad on one or both sides of a core material, and each member is assembled in a predetermined shape, and is brazed using a flux under an inert atmosphere. In general, the members are joined to form a heat exchanger.

[0003] In such a heat exchanger, Si, Cu, and the like are added to the core material of the composite material for the purpose of improving durability.
It is common to add an element that contributes to an increase in strength, such as Mg. However, the addition amount of Cu was generally at most 1.0%. However, with the increase in strength, a normal brazing temperature, for example, 6
When heated and held at 00 to 610 ° C., there is a possibility that a problem that the core material is partially melted may occur. Therefore, as a countermeasure, by adding Cu in addition to Si in the conventional brazing material and lowering the melting point of the brazing material slightly from the conventional one,
Some measures have been taken to complete the brazing operation at a temperature lower than the melting point of the core material.

In consideration of the corrosion resistance on the outer side (the brazing material side),
Potential adjustment has also been made to further add Zn to the brazing material to prevent corrosion of the core material. So-called Al-Si-Cu-Zn
A system alloy brazing material is known. (JP-A-7-88678
No.)

[0005] However, there has been a problem that cannot be solved simply by conducting the above-mentioned study on the brazing material. That is, the following problem has occurred in the process of manufacturing such an aluminum alloy composite material. After the brazing material is cast, the brazing material is hot-rolled in advance to a predetermined thickness in order to be rolled together with the core material. The process enters. However, in the brazing material having the above composition, that is, an Al alloy brazing material in which Cu and Zn are previously added in addition to Si, the Al-Si-Cu-based compound is distributed. There remains a problem in mass production that it is easy to wear and break easily, and furthermore, the brazing material and the core material are hot-rolled together, and then cold-rolled, near the end of the width of the brazing material surface during rolling. This tends to cause edge cracking, which causes a reduction in yield and breakage of the rolled material due to edge cracking, and the problem that productivity and yield significantly decrease.

[0006]

Accordingly, as a result of diligent studies, the above-mentioned problem has been solved by the present invention.

[0007] That is, the present invention provides a method for producing Mn: 0.5 to 2.0.
wt% (hereinafter, wt% is simply referred to as%), Cu: 1.3 to 2.
Al containing 5%, the balance being Al and unavoidable impurities
Si: 7 to 12%, Z on one or both sides of alloy core material
An aluminum alloy composite material containing n: 1 to 20% and coated with an Al alloy brazing material consisting of a balance of Al and inevitable impurities.

First, a major difference between the present invention and the prior art will be described. In the prior art, the Al-Si brazing material
By adding u, the brazing temperature can be lowered. However, as described above, Al-Si-
Since a Cu-based intermetallic compound is generated, the blade of the equipment is damaged during the cutting and facing steps during the production of the brazing material, and edge cracking occurs during rolling, resulting in a very poor yield. Therefore, there was a problem in mass productivity.

On the other hand, in the present invention, the brazing material itself does not employ a low melting point alloy. That is, Cu is added to the Al-Si alloy.
Is not added, the problem of abrasion and destruction of the equipment blade when cutting and facing the brazing material during the production of the brazing material is eliminated. Further, at the time of rolling, it is possible to solve the problems of a decrease in productivity and a decrease in yield due to edge cracks or plate breaks at the plate ends of the brazing material.

Another major feature of the present invention is that Cu added to the core material diffuses into the brazing material during the heating of the brazing, thereby changing the brazing material from an Al-Si type to an Al-Si-Cu type. (Si-based), the brazing material starts melting at a lower temperature. That is, it is possible to lower the brazing temperature achieved by the prior art, and even if a low melting point alloy is used for the core material, there is no concern that the core material will melt during brazing.
Further, since the furnace temperature during the brazing operation is lowered, a synergistic merit of lowering the energy cost is obtained. When the amount of Cu in the core material added for improving the durability in the prior art is ≦ 1.0%, it is difficult to sufficiently lower the brazing temperature by the above mechanism.

Next, the reason why the core element is specified as described above in the present invention will be explained. Mn content is 0.5 to 2.
If it is less than 0.5%, the strength cannot be ensured, and if it exceeds 2.0%, a large amount of Al-Mn intermetallic compound is formed, which may cause edge cracking during production rolling. Because it comes. Desirably, 0.9 to 1.6% is good.

The reason why the Cu content is specified to be 1.3 to 2.5% is that if it is less than 1.3%, the amount of Cu diffusion from the core material to the brazing material during the heating of the brazing material is small, so that the effect of lowering the melting point of the brazing material. This is because if the ratio is smaller than 2.5%, the rollability of the composite material is reduced, and a problem occurs that ear cracks and plate breaks occur. Desirably, 1.6 to 2.2% is good.

The core material contains Si, M as other elements.
Addition of g, Cr, Ti, etc. may be performed as long as the properties are not impaired. For example, 0.2 to 1.0% of Si,
If Mg is added in the range of 0.01 to 0.5%, an effect of increasing strength and self-corrosion resistance can be expected. Cr is 0.01
Addition of -0.3% and Ti in the range of 0.01-0.3% can be expected to have an effect of making the structure finer and improving workability.

The reason why the brazing filler metal element is specified as described above in the present invention is as follows. Si content of 7
The reason why the content is set to １２12% is that if the content of Zn is 7% or less, even if the amount of Zn specified in the present invention is added to the brazing material and Cu in the core material specified in the present invention diffuses into the brazing material,
This is because brazing at a temperature of 0 ° C. or less becomes difficult, and if it exceeds 12%, not only the melting point of the brazing material does not decrease, but also a problem that the brazing material erodes the core material appears.

The reason for adding Zn is that it is necessary to adjust the potential against Cu diffusion from the core material, and the brazing material needs to have a lower potential than the core material in consideration of the corrosion resistance of the brazing material side. is there. The reason why the Zn content is set to 1 to 20% is that if the content is less than 1%, the above effect is not obtained, and if the content exceeds 20%, the rollability becomes extremely poor. Preferably,
7-17% is good. There is no problem in adding a trace amount of other elements to the brazing material as long as the properties are not impaired.

Thus, by defining the amounts of Si and Zn in the brazing material and the amount of Cu in the core material within the scope of the present invention, Cu is sufficiently diffused from the core material to the brazing material during brazing, For the first time, lower the brazing temperature (conventional 595-605 ° C → 5
Low temperature to 70 to 580 ° C.) and good brazing properties can be obtained.

Further, in the present invention, a conventional method such as a method of coating a brazing material on a core material by a clad rolling method, or a method of coating a brazing material on a core material by powder application (a mixture of a binder and a flux) in a final step. The effect of the present invention can be sufficiently exhibited by any of the coating methods being performed.

[0018]

EXAMPLE A core material and a brazing alloy having the compositions shown in Table 1 were cast, respectively, and after facing, were subjected to a homogenization treatment, and were joined by hot rolling, cold rolling, intermediate annealing, and then cold rolling again. Rolling was performed to obtain base plates of aluminum alloy composite materials No. 1 to No. 9 having a plate thickness of 0.25 mm. The obtained base plate was subjected to electric resistance welding to form a tube, and the tube was assembled with a corrugated 0.08 mm-thick fin (JIS3003 alloy + 1.5% Zn). This was immersed in a suspension having a flux concentration of 5%, dried with hot air, and then heated at 580 ° C. by brazing to prepare N = 3 simple cores in one stage. Two of them were used to evaluate the brazing property, and the remaining one was used to evaluate the corrosion resistance of the brazing material side.

The brazing test was performed by counting the number of completely joined portions of the fins and tubes of the simple core by brazing to determine the adhesion ratio. In addition, the corrosion resistance test is one cycle of spraying with 5% NaCl solution (temperature of 50 ° C, humidity of 95% for 3 hours) → wet (temperature of 30 ° C, humidity of 90%, 1 hour) → drying (temperature of 50 ° C, humidity of 35%, 4 hours) The dry / humidity test was performed for 60 cycles. Regarding the brazing bondability of these test results, those with an adhesion rate of 95% or more are marked with a circle in Table 1 and those with an adhesion rate of less than 95% are marked with a cross in Table 1, and the corrosion resistance is shown in Table 1 for the maximum pit depth of the tube Are 100 μm or less, and are also shown in Table 1 as ○ marks.

[0020]

[Table 1]

In the composite materials Nos. 1 to 7 of the present invention, brazing at 580 ° C. was successfully performed without any problem. Also, the corrosion resistance is good. On the other hand, the composite material of Comparative Example No. 8 has no problem in corrosion resistance, but since the Cu content of the core material is outside the range of the present invention, the brazing material is not sufficiently melted at 580 ° C., and the brazing is not successfully performed. No. 9 shows the Cu content of the core material and the Zn content of the brazing material.
Since the amount was larger than the specified value of the present invention, rolling was not possible and evaluation was not possible.

[0022]

As described above, according to the present invention, a low melting point brazing material composition is formed in an aluminum alloy composite material comprising a core material and a brazing material by diffusion of Cu from the core material to the brazing material when the brazing is applied. Thus, the brazing operation can be performed at a lower temperature than before. In addition, lowering the temperature of the brazing furnace can reduce energy costs.

────────────────────────────────────────────────── ─── Continued on the front page (51) Int.Cl. ⁶ Identification code FI B23K 35/28 310 B23K 35/28 310B F28F 21/08 F28F 21/08 B

Claims (1)

[Claims] 1. Mn: 0.5 to 2.0 wt%, Cu: 1.
One or both sides of an Al alloy core material containing 3 to 2.5 wt%, the balance being Al and inevitable impurities, Si: 7 to
An aluminum alloy composite material containing 12 wt% and Zn: 1 to 20 wt%, and coated with an Al alloy brazing material comprising the balance of Al and inevitable impurities.