JPH0790457A - Al alloy clad material having excellent pitting corrosion resistance even after brazing heating treatment - Google Patents

Abstract

PURPOSE:To obtain an Al allay clad material showing excellent pitting corrosion resistance even if being subjected to brazing heating treatment. CONSTITUTION:In an Al alloy clad material obtd. by cladding one side or both sides of the core material with a sacrificial anode material and in an Al alloy clad material obtd. by cladding one side of the core material with a sacrificial anode material and the other side with an Al-Si alloy brazing filler metal, the core material is constituted of an Al alloy contg., by weight, 0.5 to 2% Mn and 0.2 to 1% Fe and contg., at need, one or more kinds among 0.3 to 1.2% Si, 0.05 to 5% Mg, 0.05 to 0.25% Cr, 0.05 to O.25% Zr, 0.02 to 0.25% Ti and 0.05 to 0.25% V. The sacrificial anode material is constituted of an Al alloy contg. 0.01 to 0.15% Sn, 0.05 to 1% Zn and 0.002 to 0.15% Fe and contg., at need, 0.1 to 4.5% Mg.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a working fluid passage forming member for a heat exchanger such as a radiator or a car air conditioner,
Furthermore, when used as structural members for various equipment such as water supply and drainage pipe materials for solar water heaters, water storage tank materials, etc., Al that has excellent pitting corrosion resistance even after the brazing heat treatment necessary for assembly The present invention relates to an alloy clad material.

[0002]

2. Description of the Related Art Generally, an Al alloy clad material obtained by clad a sacrificial anode material on one side or both sides of a core material or a sacrificial anode material on one surface of the core material is used for forming structural members of the above various equipments. An Al alloy clad material obtained by clad with a brazing material of an Al-Si alloy is used on the other surface. Further, the core material of the Al alloy clad material contains Mn: 0.5 to 2% in weight% (hereinafter,% means weight%), and further Si: 0.3 if necessary. ~ 1.2%,
Mg: 0.05-5%, Cr: 0.05-0.2
5%, Zr: 0.05 to 0.25%, Ti: 0.0
2 to 0.25%, V: 0.05 to 0.25%, one or more of the above, and the remainder is composed of an Al alloy having a composition of Al and inevitable impurities,
The sacrificial anode material is Sn: 0.01 to 0.15%,
Zn: 0.05 to 1%, and if necessary, Mg: 0.1 to 4.5%, with the balance being an Al alloy having a composition of Al and unavoidable impurities. It is also known to have been done.

[0003]

However, the conventional method A described above is used.
In the l-alloy clad material, when it is subjected to a brazing heat treatment for assembling, in the sacrificial anode material constituting the clad material, as an alloy component that has been solid-solved in the base material during the cooling process from the brazing temperature. The Sn component of is precipitated at the grain boundaries, and the Sn content of the base material is substantially reduced, so that it becomes electrochemically noble, and an increase in the potential cannot be avoided by that amount. On the other hand, in the concentric material, On the contrary, Sn that has diffused from the sacrificial anode material during the brazing heat treatment forms a solid solution in the base material to lower the potential of the base material. In this way, the sacrificial anode material raises the potential and the core material lowers the potential. Since the sacrificial anode material has a reduced anticorrosion effect on the core material, there is a problem that pitting corrosion is likely to occur during practical use.

[0004]

Therefore, the present inventors have
From the above viewpoints, in order to develop an Al alloy clad material having excellent pitting corrosion resistance even when subjected to brazing heat treatment, as a result of conducting research by focusing on the above conventional Al alloy clad material, In the conventional Al alloy clad material, Fe is used as an alloy component in the sacrificial anode material constituting the clad material.
Is contained in a proportion of 0.002 to 0.15%, the Fe component significantly suppresses the precipitation of the Sn component, which forms a solid solution in the matrix during the cooling process from the brazing temperature, at the grain boundaries, and the Sn component is Since the solid solution is maintained in the base material, the rise of the potential is suppressed, and the excellent sacrificial anode effect by the Sn component is secured, and the same core component has the same Fe component as the alloy component. When contained in a proportion of 0.2 to 1%, this Fe component is combined with the Sn component and Al component diffused from the sacrificial anode material during the brazing heat treatment, and Al-Fe-Sn is cooled in the cooling process from the brazing temperature. Since it precipitates as an intermetallic compound of the system, it becomes possible to avoid the solid solution of the Sn component in the matrix. As a result, the sacrificial anode material and the core material are electrochemically brazed and heated after brazing. Before processing Since maintaining the status is to obtain the results of a study of keeping excellent pitting corrosion resistance.

The present invention has been made on the basis of the above research results. An Al alloy clad material obtained by clad a sacrificial anode material on one or both sides of a core material, and a sacrificial anode on one surface of the core material. In an Al alloy clad material in which a brazing material of an Al-Si alloy is clad on the other surface, the core material is Mn: 0.5 to 2%, F
e: 0.2 to 1%, and if necessary, S
i: 0.3 to 1.2%, Mg: 0.05 to 5%,
Cr: 0.05-0.25%, Zr: 0.05-0.
25%, Ti: 0.02 to 0.25%, V: 0.05
To 0.25%, one or more of which is A, and the balance is Al and unavoidable impurities.
1 alloy, the sacrificial anode material is Sn: 0.01
~ 0.15%, Zn: 0.05-1%, Fe: 0.0
02-0.15%, and if necessary, M
g: 0.1 to 4.5%, and the remainder being an Al alloy having a composition of Al and inevitable impurities, which has excellent pitting corrosion resistance even after brazing heat treatment.
This is characterized by the l alloy clad material.

Next, the reason why the component compositions of the Al alloy constituting the core material and the sacrificial anode material of the Al alloy clad material of the present invention are limited as described above will be explained. A. Core material (a) Mn The Mn component improves the strength of the core material, makes the core material electrochemically noble, and raises the potential as compared with the sacrificial anode material so that the sacrificial anode material has a sufficient sacrificial anode material. Although it has an effect of exerting the effect, if the content is less than 0.5%, the desired effect cannot be obtained on the other hand, while the content is 2%.
%, The rolling workability deteriorates, and the intergranular corrosion susceptibility increases, so the content is set to 0.
It was set at 5 to 2%.

(B) Fe As the Fe component, the Sn component diffused from the sacrificial anode material during the brazing heat treatment as described above is a cooling process from the brazing temperature (in this case, cooling means such as air cooling or forced air cooling). However, the cooling rate is generally within the range of 20 to 200 ° C./min), and the Sn component is solid-dissolved in the matrix by precipitating it as an Al-Fe-Sn intermetallic compound. Has a function of preventing a decrease in potential due to, and maintaining a predetermined potential difference with the sacrificial anode material, but its content is 0.2
If the content is less than 0.1%, the desired effect cannot be obtained, while if the content exceeds 1%, the rolling workability and the corrosion resistance are deteriorated, so the content is 0.2 to 1%.
I decided.

(C) Si, Mg, Cr, Zr, Ti,
And V Since any of these components has the effect of improving the strength of the core material, it is contained if necessary, but their contents are respectively less than Si: 0.3% and Mg: 0.05%. Less than, Cr: less than 0.05%, Zr: less than 0.05%, T
If i: less than 0.02% and V: less than 0.05%, the desired strength-improving effect cannot be obtained, while the contents are Si: 1.2%, Mg: 5%, Cr: 0. 25%,
Zr: 0.25%, Ti: 0.25%, and V: 0.
If it exceeds 25%, the corrosion resistance and the rolling workability are deteriorated. Therefore, the contents are Si: 0.3 to 1.2%, Mg: 0.05 to 5%, and C, respectively.
r: 0.05 to 0.25%, Zr: 0.05 to 0.25
%, Ti: 0.02-0.25%, and V: 0.05
Was determined to be 0.25%.

B Sacrificial Anode Material (a) Sn The Sn component has a function of forming a solid solution in the matrix to make it electrochemically base, and exerting an excellent sacrificial anode effect, but its content is 0.01 If the content is less than 0.1%, the desired effect cannot be obtained, while if the content exceeds 0.15%, the hot workability is deteriorated. Therefore, the content is 0.01 to 0.15. Defined as%.

(B) Fe The Fe component suppresses the precipitation of the Sn component dissolved in the matrix in the grain boundaries during the cooling process from the brazing temperature during the brazing heat treatment as described above. Although it has the effect of preventing the excellent sacrificial anode effect from being lowered by the components, if its content is less than 0.002%, the desired effect is not obtained on the other hand, while its content is less than 0.
If it exceeds 15%, the crystal grains become coarse and the hot workability is rapidly deteriorated. Therefore, the content thereof is set to 0.002 to 0.15%.

(C) Zn The Zn component has the effect of changing the corrosion form to a full-face type and thereby improving pitting corrosion resistance, but its content is 0.05%.
If the content is less than the above, the desired effect cannot be obtained, while if the content exceeds 1%, the corrosion rate sharply increases, which causes the shortening of the service life.
It was set at 5 to 1%.

(D) Mg Since the Mg component has a function of forming a solid solution in the matrix and improving the room temperature strength without impairing the action of the Sn component, it is contained as necessary, but its content is 0. When the content is less than 1%, the desired strength improving effect cannot be obtained, and when the content exceeds 4.5%, the hot workability is deteriorated. It was set at 5%.

[0013]

EXAMPLES Next, the Al alloy clad material of the present invention will be specifically described by way of examples. Table 1 by the usual dissolution method
To Al alloys for core materials, Al alloys for sacrificial anode materials, and Al alloys for brazing materials, each of which has the component composition shown in FIGS. After subjected to homogenizing heat treatment, hot rolled to a plate thickness: 8 mm
The hot-rolled sheet for sacrificial anode material and the brazing material is cold-rolled. For the sacrificial anode material, the thickness of the single-sided clad is 0.9 mm, the double-sided clad. In this case, the thickness is 1 mm, and for the brazing material, the thickness is 1 mm. In this state, the hot-rolled core material, the cold-rolled sacrificial anode material, and the brazing material are used. The cold-rolled sheets for materials are stacked according to the combinations shown in Tables 6 and 7, clad by hot rolling, and then cold rolled to give a sheet thickness of 0.5 mm. Clad materials 1 to 16 and conventional Al alloy clad materials 1 to 10
Were manufactured respectively.

Then, test pieces were cut out from the various Al alloy clad materials obtained as a result, and the test pieces were used to prepare a core material and a sacrificial anode material constituting the same in a 3.5% NaCl solution at room temperature. The pitting potential was measured, and the test piece was then brazed by heat treatment. That is, the Al alloy clad material clad with Al alloys a and b for brazing was used in a vacuum of 10 ^-4 torr and other Al. The alloy clad material was held in a nitrogen atmosphere at a temperature of 600 ° C. for 5 minutes and then heat-treated under the conditions of air cooling. The pitting corrosion potential of the test piece after the heat treatment was measured under the same conditions as above, and further 1
30 in 40 ° C tap water containing ppm Cu ⁺⁺ ions
The corrosion test of immersion for a day was performed to measure the maximum pitting depth. The measurement results are shown in Tables 6 and 7.

[0015]

[Table 1]

[0016]

[Table 2]

[0017]

[Table 3]

[0018]

[Table 4]

[0019]

[Table 5]

[0020]

[Table 6]

[0021]

[Table 7]

[0022]

From the results shown in Tables 1 to 7, the present invention A
In the 1-alloy clad materials 1 to 16, during the cooling process from the brazing temperature during the brazing heat treatment, the Sn component contained in the sacrificial anode material is suppressed from precipitating at the grain boundaries due to the action of the Fe component. The potential rise of the sacrificial anode material after the brazing heat treatment is extremely small, and the Sn component diffused from the sacrificial anode material during the brazing heat treatment by the Fe component contained in the core material is cooled in the cooling process from the brazing temperature. Since it precipitates as an intermetallic compound and does not form a solid solution in the matrix,
The core material also holds the same potential as before the brazing heat treatment, and as a result, a potential difference that is the same as that before the brazing heat treatment is secured between the core material and the sacrificial anode material even after the brazing heat treatment,
It is clear that the sacrificial anode material exerts an excellent sacrificial anode effect and well protects the core material from corrosion. On the other hand, in the conventional Al alloy clad materials 1 to 10, the potential of the sacrificial anode material is changed by the brazing heat treatment. It rises, the potential of the core material decreases, and the potential difference between the two becomes extremely small, so that it is clear that pitting corrosion easily occurs in the core material.

As described above, in the Al alloy clad material of the present invention, even if the brazing heat treatment is performed, the sacrificial anode material and the core material constituting the same have a potential difference that is almost unchanged from that before the brazing heat treatment. Since the sacrificial anode material corrodes the core material well in the various equipment devices assembled by brazing and using the same, the excellent performance is exhibited for a remarkably long time.

Claims (4)

[Claims] 1. An Al alloy clad material obtained by clad a sacrificial anode material on one or both sides of a core material, and a sacrificial anode material on one surface of the core material and an brazing material of an Al--Si alloy on the other surface. In the Al alloy clad material obtained by the above, a composition containing the above-mentioned core material by weight%, Mn: 0.5 to 2%, Fe: 0.2 to 1%, and the balance of Al and unavoidable impurities Al alloy, which has the above sacrificial anode material, by weight%
Then, Sn: 0.01 to 0.15%, Zn: 0.05 to 1
%, Fe: 0.002 to 0.15%, and the balance being an Al alloy having a composition of Al and unavoidable impurities, which is excellent in hole resistance even after brazing heat treatment. Al alloy clad material having corrosion resistance. 2. An Al alloy clad material in which a sacrificial anode material is clad on one or both sides of a core material, and a sacrificial anode material on one surface of the core material and an brazing material of an Al--Si alloy on the other surface. In the Al alloy clad material obtained by the above, the core material contains, by weight%, Mn: 0.5 to 2%, Fe: 0.2 to 1%, and further Si: 0.3 to 1. 2%, Mg: 0.05-5
%, Cr: 0.05 to 0.25%, Zr: 0.05 to 0.
25%, Ti: 0.02 to 0.25%, V: 0.05 to 0.2
5%, one or more of them, and the balance being an Al alloy having a composition of Al and unavoidable impurities, wherein the sacrificial anode material is, by weight%, Sn: 0.01 ~ 0.15%, Zn: 0.05-1
%, Fe: 0.002 to 0.15%, and the balance being an Al alloy having a composition of Al and unavoidable impurities, which is excellent in hole resistance even after brazing heat treatment. Al alloy clad material having corrosion resistance. 3. An Al alloy clad material obtained by clad a sacrificial anode material on one or both sides of a core material, and a sacrificial anode material on one side of the core material and a brazing material of an Al--Si alloy on the other side. In the Al alloy clad material obtained by the above, a composition containing the above-mentioned core material by weight%, Mn: 0.5 to 2%, Fe: 0.2 to 1%, and the balance of Al and unavoidable impurities Al alloy, which has the above sacrificial anode material, by weight%
Then, Sn: 0.01 to 0.15%, Zn: 0.05 to 1
%, Fe: 0.002 to 0.15%, further, Mg: 0.1 to 4.5%, and the balance being an Al alloy having a composition of Al and unavoidable impurities. An Al alloy clad material having excellent pitting corrosion resistance even after brazing heat treatment, characterized in that. 4. An Al alloy clad material obtained by clad a sacrificial anode material on one or both sides of a core material, and a sacrificial anode material on one surface of the core material and a brazing material of an Al--Si alloy on the other surface. In the Al alloy clad material obtained by the above, the core material contains, by weight%, Mn: 0.5 to 2%, Fe: 0.2 to 1%, and further Si: 0.3 to 1. 2%, Mg: 0.05-5
%, Cr: 0.05 to 0.25%, Zr: 0.05 to 0.
25%, Ti: 0.02 to 0.25%, V: 0.05 to 0.2
5%, one or more of them, and the balance being an Al alloy having a composition of Al and unavoidable impurities, wherein the sacrificial anode material is, by weight%, Sn: 0.01 ~ 0.15%, Zn: 0.05-1
%, Fe: 0.002 to 0.15%, further, Mg: 0.1 to 4.5%, and the balance being an Al alloy having a composition of Al and unavoidable impurities. An Al alloy clad material having excellent pitting corrosion resistance even after brazing heat treatment, characterized in that.