JPS58130243A - Aluminum alloy thin plate for heat exchanger excellent in high-temperature sagging and sacrificial anode property - Google Patents

Abstract

PURPOSE:To obtain an Al alloy thin plate for a heat exchanger having excellent high-temperature sagging and sacrificial anode properties, which consists of Zn and Mn in each prescribed ratio and the balance Al with inevitable impurities. CONSTITUTION:A titled Al alloy thin plate has composition which consists of 0.5-8.0% Zn and 0.5-1.5% Mn, by weight and the balance Al with inevitable impurities. This Al alloy thin plate has above described excellent characteristics, therefore, in case when it has been used especially for a fin material of a usual heat exchanger, corrosion of a pipe body can be prevented completely owing to an excellent sacrificial anode effect of the fin. Also, when brazing the pipe body with the fin material, the shape in case of assembling is held as it is even after brazing, therefore, a dense or sparse distribution of arrangement of the fin is not resulted. As a result, cooling and heating are executed uniformly and efficiently, and the performance and service life are improved.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an aluminum alloy (A1 alloy) thin plate for heat exchangers, which has excellent high-temperature sag properties and sacrificial anodic properties.

In general, the fin materials used in lassoators for motorcycles, automobiles, etc. and condensers for coolers (hereinafter collectively referred to as heat exchangers) meet AA standard 10.
50 material (AQ of 99.5% or more).

3003 material (AA -1,2%Mn) and 70
A thin plate of 72 material (/V, -1.2% Zn) or a thin plate of brazing material cladding is used. Manufactures exchangers.

However, the above conventional AQ and A1 constituting the fin material
Because thin alloy plates have poor high-temperature sag properties (see Examples below), brazing the fin material to the pipe body sometimes deforms due to external force and its own weight, and the brazing may not maintain the shape of the fin material before brazing. The problem is that there is no.

In addition, 7072 is said to have relatively good sacrificial anodic properties.
In the case of alloys, when a heat exchanger is manufactured by joining fin materials made of this alloy to tube bodies by vacuum brazing, the Zn component evaporates from the fin materials, reducing its sacrificial anodic property. During use, corrosion often occurs in the pipe body, shortening the product's lifespan.

From the above-mentioned viewpoint, the present inventor conducted research to obtain an At alloy thin plate particularly suitable for use as a fin material of a heat exchanger, and as a result, the results were as follows:

Zn: 0.5-8.0%1 Mn', 05-1.5%, Contains AC and unavoidable impurities: remainder.

It was discovered that the M alloy thin plate having the composition of

This invention was made based on the above knowledge, and the reason why the component composition range was limited as described above will be explained below.

(al Zn The Zn component has the effect of improving the sacrificial anodic properties of the alloy thin plate, but if its content is less than 0.5%, it is not possible to secure the desired excellent sacrificial anodic properties, so it should not be contained in an amount of 0.5% or more. However, if the content exceeds 8.0%, the sag properties will deteriorate and the melting point of the alloy thin plate will be lowered, resulting in high temperature heating (sometimes partial melting) during brazing. Therefore, the content should not exceed 8%.

(b) Mn The Mn component has the effect of improving the sagging properties of the alloy thin plate and suppressing the evaporation of Zn during brazing and preventing the deterioration of the sacrificial anodic property, but if the Mn content is less than 0.5% Since the desired effect cannot be obtained in this case, the content must be 0.5% or more. However, even if the content exceeds 1.5%, no further improvement in the effect will be seen, so the upper limit was set at 1.5%.

Next, the M alloy thin plate of the present invention will be explained based on examples and comparative examples.

EXAMPLE M alloys having the compositions shown in Table 1 were melted and cast using a conventional melting method to form an ingot.

450M thick) were each kept at a temperature of 580° C. for 24 hours and subjected to soaking treatment, and then the top and bottom surfaces were removed by mechanical shaving by a thickness of 5 mm.

In this way, the face-cut ingot was made to a thickness of 440mm, and the temperature was 510mm.
After hot-rolling at 0.degree. C. to a thickness of 8u, it was cold-rolled to a thickness of 2u. Then, after performing intermediate annealing at a temperature of 400°C for 1 hour, the thickness was reduced by cold rolling to a thickness of 0.5 mx, and the intermediate annealing was further performed, and the thickness was reduced by final cold rolling. By reducing the thickness of 0.05 m to 0.15 M, bare thin plates 1 to 7 of the alloy of the present invention were prepared. and comparative 7072 alloy bare alloy gold, respectively.

In addition, on each of the upper and lower surfaces of the solid ingot of the above alloy,
At 55 thicknesses! -95%5i-1,5%Mg alloy brazing filler metal is overlaid and tack-welded at the four corners on both sides (total of 8 locations), and then rolled under the same conditions as in the case of producing bare thin sheets as described above. The present invention alloy brazing material clad thin plates 1 to 7. and Comparative 7072 alloy brazing filler metal clad thin sheets were manufactured, respectively.

Then, the resulting bare sheet and brazing filler metal
1 A sag test and a sacrificial anodic test were conducted on the front clad thin plate.

First, the sag test was carried out using the above-mentioned bare thin plate and brazing metal clad thin plate, each with a length of 60 mm x width of 15 B x thickness of 0.1 mm.
A test piece with a size of 5 mg was cut out, and as shown in the schematic side view in FIG. 600℃ for 1 minute, 2 minutes, 3 minutes and 5 minutes, respectively.
Heating and holding for minutes, ■ Temperatures of 560°C, 580°C, 600°C, and 620°C
The sample was heated under the following conditions, and the drooping value t of the test piece I was measured.

The measurement results are shown in Tables 2 and 3.

As is clear from the results shown in Tables 2 and 3, the alloy thin sheets of the present invention exhibit significantly superior sag resistance compared to the comparative 7072 alloy thin sheets in both bare thin sheets and brazing metal clad thin sheets. .

In general, it is considered practical to have a sagging value of 5 or less when held at each temperature in the table above for 3 to 5 minutes. Since the value exceeds 12.5 myn9, it is not practical, and similarly, it is only barely practical for thin plates when the heating time is 3 minutes or less.

Table 2 Table 3 On the other hand, the thin alloy sheets of the present invention show a maximum drooping value of only 8.5 B even in the case of the brazing metal clad thin sheets, indicating excellent sag resistance sufficient for practical use.

Next, the sacrificial @ anodic test was performed using the bare thin plate and the brazing metal clad thin plate, each having a length of 140 mm and a width of 20 mm.
Nine specimens each having dimensions of 0.15 mm x 0.15 mm were cut out, and as shown in the schematic perspective view in Fig. 2,
For bare thin plate specimen 3', core material; AA Standard 3003
Material, brazing material: Same X4004 material (AM-9,5%5i-
1.5%Mg) length 140 mm x width 'zomm
x thickness 1. ○ On the upper surface of the brazing metal clad flat plate 4 with the same dimensions as 1050 mm, the brazing metal clad thin plate test pieces 3' were erected by vacuum brazing at 7 mm intervals.
This was erected on the upper surface of a bare flat plate 4' made of material (995% 1 SO L Ap) in the same manner as in the case of the bare thin plate test piece described above, to form a sacrificial anodic test assembly A. , Next, this assembly was soaked in 5% saline solution at a temperature of 30°C.
1 hour of soaking for 0 minutes, pulling out and forced drying for 50 minutes
4 Alternate immersion cycles were performed for 90 days, and pitting corrosion occurring on the side surfaces of the brazed test pieces of the brazing material clad flat plate 4 and the bare flat plate 4' was observed. , this observation result is the fourth
shown in the table.

As is clear from the results shown in Table 4, the thin alloy sheet of the present invention exhibits excellent sacrificial anodic properties both when used as a raw material and when used as a brazing material clad material. Only slight corrosion is observed when the amount is low, and no corrosion occurs at all in other cases, whereas the ratio! In the case of the 1.27072 alloy thin plate, due to poor sacrificial anode properties, a large number of pitting corrosion occurs in the flat plate that is the mating material.

As mentioned above, the M alloy thin plate of the present invention has excellent sag properties and sacrificial anode properties, so when it is used as a fin material for a normal heat exchanger, it can be used as a sacrificial anode with excellent fin properties. As a result, corrosion of the pipe body can be completely prevented, and when the pipe body and fin material are brazed, the shape at the time of assembly is maintained as it is after brazing, so there is no unevenness in the fin material. As a result, cooling and heating can be performed uniformly and efficiently, resulting in useful effects such as improved performance and service life.

[Brief explanation of the drawing]

FIG. 1 is a schematic side view showing a sag test mode, and FIG. 2 is a schematic perspective view of the sacrificial anode test assembly. In the drawings: 1... Sag test piece, 2... Stainless steel stand,
A... Sacrificial anodic test assembly, 3.3'... Test piece, 4.4'... Flat plate. Applicant Mitsubishi Aluminum Co., Ltd. Agent Tomi 1) Kazuo and one other person Figure 1!

Claims (1)

[Claims] Zn, 05-80%1), only 5-1.5%, AQ and unavoidable impurities: the remainder (more than % by weight). Aluminum alloy thin plate for heat exchangers with excellent sacrificial anode properties.