JPH0790427A - Copper alloy excellent in resistance to ant's lair-form corrosion - Google Patents

Abstract

PURPOSE:To obtain a copper alloy for the tube material of a heat exchanger excellent in resistance to an ant's lair-form corrosion by specifying the chemical compsn. of a material. CONSTITUTION:This copper alloy has a compsn. consisting of 0.01-2wt.% Te, 0.005-0.5wt.% P and the balance Cu or further contg. 0.005-0.5wt.% Zr and/or W and/or 0.005-5wt.% Sn and/or Zn. This alloy has improved resistance to an ant's lair-form corrosion as the tube material of a heat exchanger and can stably be used over a long period of time.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a copper alloy having excellent resistance to ant nest corrosion and suitable for use as, for example, a pipe material of a heat exchanger.

[0002]

2. Description of the Related Art Conventionally, many copper alloys have been used as a tube material for heat exchangers, including the phosphorus-deoxidized copper alloy described in JP-A-63-247326.

[0003]

However, miniaturization and weight reduction of heat exchangers have been remarkable in recent years, and along with this, it has been desired that the pipes constituting the heat exchangers also be made thin.
In the pipe material manufactured from the above various conventional copper alloys,
In particular, ant nest-like corrosion is likely to occur, and due to the progress of the corrosion, the service life is reached in a relatively short time due to the penetration of the thinned pipe.

[0004]

From the above viewpoints, the present inventors have conducted research to develop a copper alloy that is particularly excellent in ant nest corrosion resistance. of%
Indicates weight%) Te: 0.01 to 2%, P: 0.005 to 0.5%, and (a) Zr and W of (a)
1 type or 2 types: 0.003 to 1%, (b) 1 of Sn and Zn
Species or two types: 0.05 to 5%, a copper alloy containing either or both of (a) and (b) above, and the balance of Cu and unavoidable impurities, has excellent ant nest-like corrosion resistance. Therefore, when this is used as, for example, a pipe material of a heat exchanger, there is no risk of occurrence of a leakage accident, and a research result that stable and excellent performance is exhibited for a long period of time was obtained.

The present invention was made on the basis of the above-mentioned research results, and the reason why the component composition is limited as described above will be explained below.

(A) Te Te component has an action of improving ant nest corrosion resistance, but if the content thereof is less than 0.01%, a desired excellent ant nest corrosion resistance can be secured. However, if the content exceeds 2%, the workability deteriorates. Therefore, the Te content is 0.01 to 2
Defined as%.

(B) The PP component has a deoxidizing action, and when added at the same time as Te, it has an action of preventing a remarkable decrease in workability that occurs when Te and oxygen coexist, but its content is If it is less than 0.005%, the desired effect cannot be obtained, and if the content is more than 0.5%, the workability tends to decrease, so the content was defined as 0.005 to 0.5%.

(C) Zr and W These components have the action of refining the structure and improving the strength, so they are contained as necessary, but if the content is less than 0.003%, the desired strength improving effect is obtained. Is not obtained,
On the other hand, if the content exceeds 1%, the workability deteriorates, so the content was set to 0.003 to 1%.

(D) Sn and Zn Both of these components form a solid solution in the base material to make them electrochemically base, thereby making the corrosion a general corrosion type and having a pitting corrosion resistance action, so they are contained as necessary. However, its content is 0.
If it is less than 05%, the desired effect cannot be obtained, while if it exceeds 5%, the workability is rather deteriorated. Therefore, the content is set to 0.05 to 5%.

[0010]

EXAMPLES Next, the copper alloy of the present invention will be specifically described by way of examples.

In a normal melting furnace, a molten copper alloy having the composition shown in Tables 1 and 2 is melted, cast into a 5 kg ingot, and after forging the ingot, the face is cut and the intermediate is cut. Cold rolled, outer diameter: 15.88mm, wall thickness: 1.00mm,
Length: A pipe material having a dimension of 3000 mm, which was annealed at 520 ° C. in a reducing atmosphere to give a copper alloy material of the present invention 1
25 and conventional copper alloy materials (phosphorus deoxidized copper alloy materials) were manufactured.

Test pieces having a length of 300 mm were cut out from the above-described copper alloy materials 1 to 25 of the present invention and conventional copper alloy materials, and subjected to a corrosion test. In the corrosion test, one end of the test piece was sealed with a silicon stopper, and 2 ml of a corrosive liquid consisting of 1 vol.% Formic acid was placed in the test piece.
After injecting, seal the other end with a silicon stopper, and place it in a constant temperature water tank in the longitudinal direction so that it is half-immersed in water.Keep the constant temperature water tank at 25 ° C for 12 hours, then at 40 ° C for 12 hours. Holding was performed for 1 cycle, and this was performed for 90 cycles.

After completion of the above-mentioned corrosion test, each test piece was cut in the longitudinal direction, the cut surface was polished, and observed with an optical microscope to measure the presence or absence of ant nest corrosion and the maximum erosion depth. The results are shown in Tables 1 and 2.

[0014]

【table 1】

[0015]

[Table 2]

[0016]

As is clear from the results shown in Tables 1 and 2, in the copper alloy materials 1 to 25 of the present invention, ant nest corrosion does not exist, while in the conventional copper alloy materials, The occurrence of remarkable ant nest corrosion is observed. As described above, the copper alloy of the present invention is excellent in ant nest corrosion resistance,
Therefore, particularly when this copper alloy is used as a tube material of a heat exchanger, it exhibits stable and excellent performance over a long period of time, and further exhibits an excellent effect in which its reliability is further improved.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Masato Watanabe 1230 Kamijideya, Okegawa City, Saitama Prefecture Mitsubishi Material Co., Ltd. Kitamoto Works

Claims (5)

[Claims] [Claim 1] Te: 0.01 to 2%, P: 0.005 to 0.5% by weight
%, And the balance is composed of Cu and unavoidable impurities, and a copper alloy excellent in ant-nested corrosion resistance. 2. By weight%, Te: 0.01 to 2%, P: 0.005 to 0.5
%, 1 type or 2 types of Zr and W: 0.003 to 1%, and the balance is composed of Cu and unavoidable impurities, and a copper alloy excellent in ant nest corrosion resistance. . 3. By weight%, Te: 0.01 to 2%, P: 0.005 to 0.5
%, One or two of Sn and Zn: 0.05 to 5%, and the balance is composed of Cu and unavoidable impurities, and a copper alloy excellent in ant nest corrosion resistance. . 4. By weight%, Te: 0.01 to 2%, P: 0.005 to 0.5
%, 1 or 2 kinds of Zr and W: 0.003 to 1%, 1 or 2 kinds of Sn and Zn: 0.05 to 5%, and the balance of Cu and inevitable impurities. A copper alloy with excellent ant nest corrosion resistance. 5. The copper alloy according to claim 1, characterized in that it is used as a tube material of a heat exchanger.