JPH08243734A - Production of aluminum base product - Google Patents

Abstract

PURPOSE: To obtain a heat exchanger, etc., made of Al having excellent corrosion resistance by executing the heat treatment at a specific temperature and for a specified time after brazing. CONSTITUTION: For example, a brazing sheet of 0.4mm thickness obtd. by cladding (clad ratio is 10% on one side) an Al-8Si-3Zn alloy brazing filler metal having a composition contg. 8wt.% Si, 3wt.% Zn, and the balance consisting of Al and inevitable impurities on both faces of a core metal of pure Al containing only inevitable impurities is prepared. A tube is composed by using this sheet. The tube and an Al fin are assembled, and these are brazed by using a fluoride base flux in the inert gas atmosphere. After that, the heat treatment is executed to the product for >=3 minutes at the temperature of 100 to 400 deg.C. Consequently, the Al base product having excellent corrosion resistance can be obtained.

Description

Detailed Description of the Invention

[0001]

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

[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), the state of the brazing filler metal (Al-Si-Zn alloy) connecting the fin and the tube formed by using the brazing sheet is examined. did. Al-melted during brazing
In the process of cooling the Si-Zn alloy, first, the primary crystal α phase is precipitated and grows. Then, when the eutectic temperature is reached, the liquid phase is solidified to form a eutectic phase and cooled to room temperature. At this time, theoretically, the Si solid solubility of the primary crystal α phase and the Si solid solubility of the eutectic α phase are the same. 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 electrochemically more base than the primary α phase. Therefore, when in a corrosive environment, the eutectic α phase is preferentially dissolved, and the remaining primary α phase is removed, and the weight loss due to this loss contributes more than the dissolution weight loss, and the corrosion rate is high. Was thought to be. As a result, the fin and the tube are likely to come off.

Further, when the above-mentioned corrosion (grain boundary corrosion) progresses, the core material of the brazing sheet is exposed, pitting corrosion easily progresses to the core material, and through holes are easily formed. If this is a tube, it is fatal. Considering the relationship between the brazing material and the core material, the eutectic α phase has the largest potential difference from the inside of the core material, but the Si solid solubility in this eutectic α phase is not sufficiently small. Therefore, the potential difference cannot be said to be sufficient. Therefore, the brazing material cannot be expected to have a sufficient sacrificial anode effect.

From the above, it was considered important to make the solid solubility of the primary α phase and the solid solubility of the eutectic α phase equal. 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. Further, the α phase becomes a base material having a large potential difference with respect to the core material inside, the sacrificial anode effect is exerted, and pitting corrosion of the core material hardly occurs.

In order to achieve such a state, it has been found that heat treatment should be performed after the brazing work. That is, when heat treatment is performed after the brazing operation, the amount of Si dissolved in the primary crystal α phase and the amount of Si dissolved in the eutectic α phase are equal and the amount of Si solid solution is low, resulting in an electrochemical reaction. The characteristics are even,
Moreover, it becomes base on the core material. The present invention has been achieved based on such knowledge, and an object thereof is to provide an Al-based product having excellent corrosion resistance.

An object of the present invention is a method for producing a product using an Al material in which an Al-Si-Zn alloy brazing material containing at least Si and Zn is provided on the surface of a core material, and the brazing material is used. After brazing work with wood, 100-4
This is achieved by a method for manufacturing an Al-based product, which is characterized by performing heat treatment for 3 minutes or more at a temperature of 00 ° C. A method for producing a product using an Al material, in which an Al-Si-Zn alloy brazing material containing at least Si and Zn is provided on the surface of a core material made of an Al alloy containing at least Mn, the method comprising: After brazing work with wood, 100-4
This is achieved by a method for manufacturing an Al-based product, which is characterized by performing heat treatment for 3 minutes or more at a temperature of 00 ° C.

Further, at least one selected from the group consisting of Cu, Si, Zr, and Ti, and an Al-containing at least Si and Zn on the surface of a core material made of an Al alloy containing Mn.
A method of manufacturing a product using an Al material provided with a Si-Zn alloy brazing material, wherein a heat treatment is performed for 3 minutes or more at a temperature of 100 to 400 ° C after the brazing operation with the brazing material. And an Al-based product manufacturing method.

The Al material is a brazing sheet in which a brazing material is bonded (clad) on the surface (one surface or both surfaces) of the 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 or tubes are formed using such a sheet. The brazing material in the present invention is an Al-Si-Zn based alloy. In particular, the Si content is 3 to 15 wt% (more preferably 3 to 11 wt%, more preferably 5 to 10 wt%), and the Zn content is 0.1.
-15 wt% (more preferably 0.1-10 wt%, more preferably 1-10 wt%), the balance consisting of Al and unavoidable impurities. In addition, 0.001 to 0.1 wt
% In, 0.01-0.07 wt% Be, 0.02
˜0.20 wt% Bi and the like may be included.

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, and in such a case, an Al alloy is used. In particular,
An Al alloy having a Mn content of 0.1 to 1.5 wt% is used. Also, 0.05 to 0.5 wt% Cu, 0.3 to
1.2 wt% Si, 0.01 to 0.15 wt% Z
An Al alloy containing at least one of r and 0.01 to 0.2 wt% of Ti, 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.

[0011] A tube (tube or putty), which is a flow path for a heat medium formed by using a sheet made of the above-mentioned Al material, and an Al fin are combined, brazed, and then cooled. The cooled product is heat-treated at a temperature of 100 to 400 ° C. for 3 minutes or longer (preferably 10 minutes or longer). When the heat treatment temperature was low, it was not possible to eliminate the difference between the solid solubility of Si in the primary α phase and the solid solubility of Si in the eutectic α phase. On the contrary, if the temperature is too high, the same solid solubility difference occurs in the precipitation process during cooling, and the heat treatment of the present invention is meaningless. The preferable heat treatment temperature is 200 to 300 ° C. Also, when the heat treatment time is short, the primary α-phase Si
Since it was not possible to eliminate the difference between the solid solubility of Si and the solid solubility of Si in the eutectic α phase, it was set to 3 minutes or more. The heat treatment time can be long, but considering the production efficiency, 1
Within 0 hours. The preferable heat treatment time is 10 minutes to 10 minutes.
Time.

A specific embodiment will be described below.

[0013]

【Example】

[Example 1] Al-8Si-3Zn in which Si is 8 wt% and Zn is 3 wt% and the balance is Al and inevitable impurities on both surfaces of a core material made of pure Al containing only inevitable impurities.
A brazing sheet having a thickness of 0.4 mm, in which a brazing alloy material was clad (the clad ratio was 10% on one side) was prepared. Then, a tube was constructed using this brazing sheet.

This tube was combined with an Al fin, and brazing was performed at 600 ° C. for 3 minutes by a brazing means using a fluoride-based flux in an inert atmosphere to bond the tube and the fin. This heat exchanger was heat-treated under the conditions shown in Table-1, and then gradually cooled to room temperature by air cooling, and a corrosion resistance test was conducted.
The results are shown in Table-1.

Table-1 Heat treatment conditions Brazing potential (mVvsSCE) Corrosion resistance No heat treatment (as brazing) -870 Some local corrosion type Pit depth 0.12mm 50 hours after brazing at 50 ° C -875 Some local corrosion type Pitting depth 0.12mm 5 hours at 130 ° C after brazing −960 General corrosion type Pitting depth 0.04mm 3 hours at 200 ° C after brazing −955 General corrosion type Pitting depth 0.04mm At 300 ° C after brazing 1 hour -950 General corrosion type pitting corrosion depth 0.05mm 30 minutes after brazing at 300 ° C -950 General corrosion type pitting corrosion depth 0.05mm 10 minutes after brazing at 300 ° C -948 General corrosion type pitting depth 0.06 mm After brazing at 400 ° C for 3 minutes −920 General corrosion type pitting depth 0.07mm After brazing at 450 ° C for 10 minutes −900 Slightly localized corrosion type pitting depth 0.13mm * Corrosion resistance test is acid salt spray test For 1 day to check the corrosion morphology of the brazing material and Such a test was carried out for 30 days, and the pitting depth was examined.

Example 2 In Example 1, an Al-1.2Mn-0.15Cu alloy was used as the core material, and
Corrosion resistance test was conducted in the same manner except that Al-8Si-1Zn alloy was used as the brazing material.
It is shown in FIG. Table-2 Heat treatment conditions Brazing potential (mVvsSCE) Corrosion resistance No heat treatment (as brazing ) -760 Some local corrosion pitting depth 0.15mm 50 hours after brazing at 50 ° C -763 Some local corrosion pitting depth 0.15mm 5 hours at 130 ° C after brazing −910 General corrosion type pitting depth 0.03mm 3 hours at 200 ° C after brazing −906 General corrosion type pitting depth 0.04mm 1 hour at 300 ° C after brazing − 900 General corrosion type pitting depth 0.03mm After brazing at 300 ° C for 30 minutes −900 General corrosion type pitting depth 0.04mm After brazing at 300 ° C for 10 minutes −900 General corrosion type pitting depth 0.02mm Brazing After that, 400 ° C. for 3 minutes −890 general corrosion type pitting depth 0.02 mm After brazing for 10 minutes at −878 slightly local corrosion type pitting depth 0.14 mm [Example 3] In Example 1, as a core material Al-1.
2Mn-0.5Cu-0.6Si-0.1Zr alloy was used, and Al-8Si-1Zn alloy was used as the brazing material, and the same corrosion resistance test was performed. 3 shows.

Table-3 Heat treatment conditions Brazing potential (mVvsSCE) Corrosion resistance No heat treatment (as brazing) -750 Some local corrosion type Pit depth 0.15mm 50 hours after brazing at 50 ° C-690 Some local corrosion type Pitting depth 0.13mm 5 hours at 130 ° C after brazing −915 General corrosion type Pitting depth 0.04mm 3 hours at 200 ° C after brazing −909 General corrosion type Pitting depth 0.06mm At 300 ° C after brazing 1 hour -900 General corrosion type pitting corrosion depth 0.05mm After brazing at 300 ° C for 30 minutes -900 General corrosion type pitting corrosion depth 0.05mm After brazing at 300 ° C for 10 minutes -902 General corrosion type pitting corrosion depth 0.05 mm After brazing at 400 ° C. for 3 minutes −880 General corrosion type pitting depth 0.06 mm After brazing at 450 ° C. for 10 minutes −860 Slightly localized corrosion type pitting depth 0.14 mm [Comparative Example] In Example 1, Al-1.2 as material
A Mn-0.15Cu alloy is used and A is used as a brazing filler metal.
A corrosion resistance test was conducted in the same manner except that the 1-8Si alloy was used, and the results are shown in Table-4.

Table-4 Heat treatment conditions Brazing potential (mVvsSCE) Corrosion resistance No heat treatment (as brazing) -740 Pitting depth 0.40mm After brazing at 50 ° C for 50 hours -740 Pitting depth 0.35mm Brazing After 5 hours at 130 ℃ -740 Pitting depth 0.32mm After brazing 3 hours at 200 ℃ -750 Pitting depth 0.34mm After brazing at 1 hour at 300 ℃ -760 Pitting depth 0.36mm After brazing 300 30 minutes at ℃ −755 Pitting depth 0.37mm After brazing at 300 ℃ for 10 minutes −753 Pitting depth 0.35mm After brazing at 400 ℃ for 3 minutes −762 Pitting depth 0.34mm At 450 ℃ after brazing 10 minutes -745 Pitting depth 0.35mm

[0019]

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

Claims (8)

[Claims] 1. A method of manufacturing a product using an Al material in which an Al—Si—Zn alloy brazing material containing at least Si and Zn is provided on the surface of a core material, the brazing operation using the brazing material. After that, a heat treatment is performed for 3 minutes or more at a temperature of 100 to 400 ° C., a manufacturing method of an Al-based product. 2. An Al—Si containing at least Si and Zn on the surface of a core material made of an Al alloy containing at least Mn.
A method for manufacturing a product using an Al material provided with a Zn-based alloy brazing material, comprising performing a heat treatment for 3 minutes or more at a temperature of 100 to 400 ° C. after brazing with the brazing material. A method for producing a characteristic Al-based product. 3. An Al—S containing at least Si and Zn on the surface of a core material made of an Al alloy containing Mn and at least one selected from the group consisting of Cu, Si, Zr and Ti.
A method of manufacturing a product using an Al material provided with an i-Zn alloy brazing material, wherein after the brazing operation with the brazing material, a heat treatment is performed at a temperature of 100 to 400 ° C for 3 minutes or more. A method for producing an Al-based product, comprising: 4. The method for producing an Al-based product according to claim 1, wherein the Al material is a brazing material bonded to the surface of a core material. 5. The method for producing an Al-based product according to claim 1, wherein the Al material comprises a brazing material particle provided on a surface of a core material. 6. The brazing material has a Si content of 3 to 15 wt.
%, Zn content of 0.1 to 15 wt%, I if necessary
n is 0.001 to 0.1 wt% and Be is 0.01 to 0.
The method for producing an Al-based product according to any one of claims 1 to 5, wherein 07 wt% and Bi are 0.02 to 0.20 wt% and the balance is Al and inevitable impurities. 7. The method for producing an Al-based product according to claim 2, wherein the Mn content in the core material made of an Al alloy is 0.1 to 1.5 wt%. 8. The Cu content in the core material made of an Al alloy when it contains Cu is 0.05 to 0.5 wt%, S
Si content when i is included is 0.3 to 1.2 wt.
%, Zr content in the case of containing Zr is 0.01-0.
15wt%, Ti content when Ti is included is 0.0
A of claim 3 wherein the content is 1 to 0.2 wt%.
Method for manufacturing l-based product.