JPH08276265A - Manufacture of al product - Google Patents

Abstract

PURPOSE: To manufacture an Al product excellent in a corrosion resistance by stopping a primary temperature drop at a prescribed temperature lower than a brazing temperature after the brazing in the brazing work using the material consisting of the Al alloy containing Si in the core surface. CONSTITUTION: A fin is manufactured by using a brazing sheet where the pure Al or Al alloy is used as a core and a brazing filler metal consisting of an Al-Si alloy containing Si in its surface is cladded, or a sheet where the brazing powder is attached to the core surface by a thermal spraying or with the binder, and a heater exchanger is manufactured by brazing the tube. The cooling after the brazing is achieved not by simply dropping the temperature to the room temperature, but by dropping the temperature to 500-350 deg.C, and temporarily stopping the cooling work, and then, keeping the temperature at the value. The degree of Si solution of the primary crystal α phase is thereby equal to that of the eutectic αphase, and a product difficult to generate an intergranular corrosion and excellent in the corrosion resistance is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a product such as a heat exchanger using an Al-based alloy containing Si as a brazing filler metal.

[0002]

BACKGROUND OF THE INVENTION Fins (or tubes) using a brazing sheet in which a brazing material is attached to the surface of a core material
Is manufactured, the fins and tubes are combined, and brazing is performed to manufacture a heat exchanger. One of the characteristics required for this heat exchanger is that it has excellent corrosion resistance. That is, when placed in a corrosive environment, the corrosion gradually progresses. Therefore, various corrosion resistance techniques have been proposed. However, further corrosion resistance technology is required.

[0003]

DISCLOSURE OF THE INVENTION The inventors of the present invention have enthusiastically investigated the above problems. First, the conventional products were examined. That is, in a heat exchanger made of aluminum or an aluminum alloy (made of Al), a brazing material (Al-Si alloy, or Al-Si-) connecting fins and tubes formed by using a brazing sheet.
The state of Si-containing Al alloys such as Zn-based alloys) was examined. In the process of cooling the Si-containing Al alloy melted during brazing, first, the primary α phase is precipitated and grows. Then, when the eutectic temperature is reached, the liquid phase is solidified to form a eutectic phase (Si + α phase) and cooled to room temperature. At this time, theoretically, S of the primary α phase
The i solid solubility is the same as the Si solid solubility of the eutectic α phase. However, in the cooling process after solidification, Si in the eutectic α phase is likely to precipitate, and therefore, the Si solid solubility in the eutectic α phase is lower than the Si solid solubility in the primary α phase. I came. by the way,
The fact that the solid solubility of the eutectic α phase is lower than that of the primary α phase means that the eutectic α phase is in an electrochemically lower state than the primary α phase. Therefore, in a corrosive environment, eutectic α
It was considered that the phases were preferentially dissolved, and the remaining primary α phase was dropped off, and the weight loss due to this drop contributed more than the loss on dissolution and the corrosion rate was increased. As a result, the fin and the tube are likely to come off.

Further, when the above-mentioned corrosion (local corrosion such as intergranular corrosion) progresses, the core material of the brazing sheet is exposed, and pitting corrosion easily progresses to the core material, so that the through hole Are easily formed. If this is a tube, it is fatal. From this, it was considered important to make the Si solid solubility of the primary crystal α phase equal to the Si solid solubility of the eutectic α phase. In particular, it has been found that it is preferable to make the Si solid solubility of the primary crystal α phase and the Si solid solubility of the eutectic α phase equal and to reduce the Si solid solution amount. That is, in this way, the electrochemical characteristics of the α phase of the brazing material become equal, the primary α phase and the eutectic α phase are dissolved almost at the same time, and the entire surface is dissolved to cause intergranular corrosion. It will be difficult.

In order to achieve such a state, it has been understood that the cooling process after the brazing work should be devised. That is, if the cooling after the brazing work is temporarily stopped, the amount of Si dissolved in the primary α-phase and the amount of Si dissolved in the eutectic α-phase become equal, and the electrochemical characteristics are equalized. It turns out that The present invention has been achieved based on such knowledge, and A having excellent corrosion resistance is obtained.
The purpose is to provide l-based products.

An object of the present invention is a method for producing a product using an Al material in which an Al-based alloy brazing material containing at least Si is provided on the surface of a core material, which is obtained at a predetermined temperature by the brazing material. In the cooling process after the brazing operation, the temperature is temporarily stopped at a predetermined temperature lower than the brazing temperature, thereby achieving an Al-based product manufacturing method.

Further, A containing at least Si on the surface of the core material
A method of manufacturing a product using an Al material provided with an l-based alloy brazing material, comprising: a brazing temperature at a predetermined temperature-decreasing rate in a cooling process after brazing at a predetermined temperature with the brazing material. This is achieved by a method for producing an Al-based product, which is characterized in that the temperature is lowered to a low predetermined temperature, and the temperature is lowered from this predetermined temperature at a temperature lowering rate lower than the temperature lowering rate.

Although the second invention is different from the first invention, the basic principle is similar. That is, the first invention is one in which the cooling operation is temporarily stopped in the cooling process after the brazing work (the cooling is stopped at one specific temperature), whereas the second invention is brazing. This is because it can be considered that the cooling operation is gradually stopped over a long range in the cooling process after the work.

In the present invention, the brazing material is an Al-Si type alloy containing Si. S in this brazing material
The i content is preferably 3 to 11 wt%. More preferably, it is 5 to 10 wt%. Further, in order to exert a sacrificial anode effect on the brazing material, an Al-based alloy further containing Zn is preferable. The Zn content is 0.1 to 25 w
t% is preferred. More preferably 0.1 to 10 wt%,
More preferably, it is 1 to 10 wt%. In addition,
0.001-0.1 wt% In, 0.01-0.07
It may contain wt% Be, 0.02 to 0.20 wt% Bi and the like. The balance other than the above is Al and inevitable impurities. Specifically, A4343, A4104, A
Al-Si alloy such as 4045, A4343 + 10Z
n, A4104 + 10Zn, A4045 + 8Zn, etc.
An l-Si-Zn alloy is used.

The Al material of the present invention is a brazing sheet in which a brazing material is bonded (clad) on the surface (one surface or both surfaces) of a core material, or a brazing material powder (particles) is sprayed on the surface of the core material. Alternatively, a sheet attached with a binder may be used. Fins are formed using such a sheet, and tubes (particularly tubes) such as tubes and pipes are formed.

The core material is pure Al or Al alloy. Pure Al may be used if mechanical strength is not required. However, mechanical strength is often required. In such a case, an Al alloy (such as A3103, Al
-Mn-based alloy, Al-Mn-Cu-based alloy such as A3003) is used. In particular, the Mn content is 0.1 to 1.5
A wt% Al alloy is used. Also, 0.05 to 0.5
wt% Cu, 0.3-1.2 wt% Si, 0.01
~ 0.15 wt% Zr, 0.01-0.2 wt% T
An Al alloy containing at least one or more of i and 0.1 to 1.5 wt% of Mn is used. By using such an Al-Mn-based alloy or Al-Mn-X-based alloy, the mechanical strength required as the core material is secured.

[0012] A tube (tube) which is a flow path of a heat medium constituted by using a sheet made of the above Al material and an Al fin are combined and brazed at a temperature of about 590 to 615 ° C. Then, cool. This cooling process does not simply lower the temperature from the brazing temperature to room temperature.

For example, when cooling is performed to lower the temperature from the brazing temperature to a temperature of 500 to 350 ° C., the cooling operation is temporarily stopped and the state is maintained at that temperature. The holding time is preferably 10 seconds or longer, more preferably 30 seconds or longer, and particularly preferably 60 seconds or longer. This holding time may be long, but holding it for 1 hour or more does not enhance the effect and lowers the productivity. Therefore, the upper limit of the holding time is about 1 hour.

The temperature range of the temporary stop is set to 500 to 350 ° C. because the cooling operation is temporarily stopped at a high temperature exceeding 500 ° C. and the cooling operation is temporarily stopped at a low temperature below 350 ° C. However, the effect was low. The more preferable temperature range was 450 to 400 ° C. The cooling rate may be a normal one. Specifically, 5 to 300 ° C
A cooling rate of / sec is adopted.

The same thing can be expected if the cooling process is performed in multiple stages instead of suspending the cooling operation as described above. That is, 500 to 350 from the brazing temperature
In the first cooling process reaching the temperature range of ℃ (preferably 450 to 400 ℃), for example, it is cooled at a temperature decrease rate (first temperature decrease rate) of 5 to 300 ℃ / sec, and then the first
Cooling rate smaller than the rate of temperature decrease, eg 0.5 ° C / min
You may make it cool at the following temperature lowering rate (2nd temperature lowering rate). Even in this case, the Si solid solubility of the primary crystal α phase and the Si solid solubility of the eutectic α phase become uniform, and intergranular corrosion hardly occurs.

A specific embodiment will be described below.

[0017]

【Example】

[Example 1] A brazing sheet having a thickness of 0.4 mm was prepared in which a core material made of Al-1wt% Mn was clad with an Al-4wt% Si alloy brazing material (cladding ratio was 10% on one side) on both sides. Then, a tube was constructed using this brazing sheet.

This tube was combined with an Al fin, and brazing was carried out at 600 ° C. for 5 minutes by a brazing means using a fluoride type flux in an inert atmosphere. And cooling after brazing (500-35
After cooling to a temperature of 0 ° C., the cooling operation was temporarily stopped, the temperature was maintained for a predetermined time, and then cooling was performed again under the conditions shown in Table 1 below. The corrosion resistance test was conducted on the products, and the results are also shown in Table-1.

Table-1 Cooling stop temperature Cooling stop time Cooling rate Corrosion resistance Non-invention Cooling at a constant rate from the brazing temperature to room temperature (3 ° C / sec) × The present invention 360 ° C 30 minutes 10 ° C / s ◎ Invention 360 ° C. 1 hour 20 ° C./s ◎ Invention 400 ° C. 10 minutes 5 ° C./s ◎ Invention 450 ° C. 30 seconds 10 ° C./s ◎ Invention 470 ° C. 20 seconds 70 ° C./s ◎ Invention 500 ° C. 15 seconds 300 ° C / s ◎ * Corrosion resistance is 10 days for acid salt spray test (ASTMM G85-85SWAAT) ◎ mark indicates that there is no preferential dissolution of eutectic α phase, and × sign indicates preferential dissolution of eutectic α phase, and core Corrosion progresses to the material * Outside of the invention, there is no temporary cooling stop and cooling is performed from the brazing temperature to room temperature at 3 ° C / sec. [Example 2] Al-0.2wt% Mn-0.3wt% C
On both sides of the core material made of u, Al-9wt% Si-5wt
% Zn alloy brazing material clad (cladding ratio is 10
%) Brazing sheet having a thickness of 0.4 mm was prepared. Then, a tube was constructed using this brazing sheet.

This tube was combined with an Al fin, and brazing was carried out at 600 ° C. for 5 minutes by a brazing means using a fluoride type flux in an inert atmosphere. And cooling after brazing (500-35
After cooling to a temperature of 0 ° C., the cooling operation was temporarily stopped, the temperature was maintained for a predetermined time, and then cooling was performed again under the conditions shown in Table 2 below, and thus obtained. The corrosion resistance test was conducted on the products, and the results are also shown in Table 2.

Table-2 Cooling stop temperature Cooling stop time Cooling rate Corrosion resistance Non-invention Cooling at a constant rate from the brazing temperature to room temperature (3 ° C / sec) × The present invention 360 ° C 30 minutes 10 ° C / s ◎ Invention 360 ° C. 1 hour 20 ° C./s ◎ Invention 400 ° C. 10 minutes 5 ° C./s ◎ Invention 450 ° C. 30 seconds 10 ° C./s ◎ Invention 470 ° C. 20 seconds 70 ° C./s ◎ Invention 500 ° C. 15 seconds 300 ° C / s ◎ * Corrosion resistance is 10 days for acid salt spray test (ASTMM G85-85SWAAT) ◎ mark indicates that there is no preferential dissolution of eutectic α phase, and × sign indicates preferential dissolution of eutectic α phase, and core Corrosion progresses to the material * Outside the invention, there is no temporary cooling stop, and the material is cooled from the brazing temperature to room temperature at 3 ° C / sec. [Example 3] Al-on both sides of the core material made of A1070
A sheet was prepared in which a brazing filler metal powder (average particle diameter 30 μm) made of a 5 wt% Si-20 wt% Zn alloy was provided with a resin binder so as to have a ratio of 60 g / m ² . Then, a tube was constructed using this sheet.

This tube was combined with an Al fin, and brazing was carried out at 600 ° C. for 5 minutes by a brazing means using a fluoride type flux in an inert atmosphere. And cooling after brazing (500-35
After cooling to a temperature of 0 ° C., the cooling work was temporarily stopped, the temperature was maintained for a predetermined time, and then cooling was performed again under the conditions shown in Table 3 below. The corrosion resistance test was conducted on the products, and the results are also shown in Table 3.

Table-3 Cooling stop temperature Cooling stop time Cooling rate Corrosion resistance Non-invention Cooling at a constant rate from the brazing temperature to room temperature (3 ° C / sec) × The present invention 360 ° C 30 minutes 10 ° C / s ◎ Invention 360 ° C. 1 hour 20 ° C./s ◎ Invention 400 ° C. 10 minutes 5 ° C./s ◎ Invention 450 ° C. 30 seconds 10 ° C./s ◎ Invention 470 ° C. 20 seconds 70 ° C./s ◎ Invention 500 ° C. 15 seconds 300 ° C / s ◎ * Corrosion resistance is 10 days for acid salt spray test (ASTMM G85-85SWAAT) ◎ mark indicates that there is no preferential dissolution of eutectic α phase, and × sign indicates preferential dissolution of eutectic α phase, and core Corrosion progresses to the material * Outside the invention, there is no temporary cooling stop and cooling is performed from the brazing temperature to room temperature at 3 ° C / sec. [Example 4] Cooling after brazing in Example 1 (500-
After cooling to a temperature of 350 ° C. at a predetermined rate and then slowly cooling) under the conditions shown in Table 4 below, a corrosion resistance test was performed on the obtained product. Shown in.

Table-4 First cooling rate Cooling rate change temperature Second cooling rate Corrosion resistance Non-invention Cooling at a constant rate from brazing temperature to room temperature (3 ° C / sec) × Inventive 100 ° C / s 400 ℃ 0.5 ℃ / min ◎ The present invention 200 ℃ / s 450 ℃ 0.5 ℃ / min ◎ * Corrosion resistance is acid salt spray test 10 days (ASTMM G85-85SWAAT) ◎ indicates the preferential dissolution of eutectic α phase No general corrosion type X indicates preferential dissolution of eutectic α phase and corrosion progresses to core material

[0025]

According to the present invention, products such as Al heat exchangers having excellent corrosion resistance can be obtained.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location C22C 21/00 C22C 21/00 D // B23K 101: 14

Claims (7)

[Claims] 1. An Al containing at least Si on the surface of a core material.
A method of manufacturing a product using an Al material provided with a system alloy brazing material, wherein the brazing material is temporarily cooled at a predetermined temperature lower than the brazing temperature in the cooling process after the brazing operation at the predetermined temperature. A method for producing an Al-based product, characterized in that the temperature lowering is stopped temporarily. 2. An Al containing at least Si on the surface of the core material.
A method of manufacturing a product using an Al material provided with a system alloy brazing material, wherein the brazing temperature is lower than a brazing temperature at a predetermined temperature lowering rate in a cooling process after brazing at a predetermined temperature with the brazing material. A temperature is lowered to a predetermined temperature, and the temperature is lowered from the predetermined temperature at a temperature lowering rate lower than the temperature lowering rate.
Method for manufacturing l-based product. 3. The method for producing an Al-based product according to claim 1 or 2, wherein an Al-based brazing filler metal having a Si content of 3 to 11 wt% is used. 4. The method for producing an Al-based product according to any one of claims 1 to 3, wherein an Al-based alloy brazing material further containing Zn is used. 5. The brazing material further contains Zn, and an Al alloy brazing material having a Zn content of 0.1 to 25 wt% is used.
Method for manufacturing l-based product. 6. The predetermined temperature lower than the brazing temperature is 35.
The temperature is in the range of 0 to 500 ° C., The method for producing an Al-based product according to claim 1 or 2. 7. The method for producing an Al-based product according to claim 1, wherein the temperature is temporarily stopped at a predetermined temperature lower than the brazing temperature for 10 seconds or more.