JPH0321617B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a fin material with excellent corrosion resistance and sacrificial anode effect, which is used in manufacturing aluminum heat exchangers by vacuum brazing. Conventionally, in general, for example, automobile radiators,
Aluminum heat exchangers are widely used in air conditioning equipment and the like. This heat exchanger is usually made of Al (JIS1070 material) with a purity of 99.70% or more as a fin material.
Or a thin plate of Al (JIS1080 agent) with a purity of 99.80% or more, or a phrasing sheet made of a thin plate of Al (JIS1080 agent) with a core material and Al-Si alloy brazing material clad on both sides of the core material. The tube material used is Al-Mn alloy tube material formed by brazing or extrusion, or Al-Mn alloy is used as the core material, and Al-Si alloy brazing is applied to the front side of the core material. The fin material and the tube material are assembled into a heat exchanger shape by combining the fin material and the tube material in the presence of the brazing material, and vacuum brazing is performed in this state. has been done. However, in this conventional heat exchanger, the corrosion resistance of the fin material is poor, and the sacrificial anode effect of the fin material on the tube material is not sufficiently satisfactory, so that the service life of the heat exchanger is reached in a relatively short period of time. Therefore, from the above-mentioned viewpoint, the present inventors conducted research to develop a fin material that has excellent corrosion resistance and has an excellent sacrificial anode effect, that is, is electrochemically less noble than pipe material. As a result of aging, it contains Sn: 0.02-0.1%, Zn: 0.04-0.09%, and if necessary, Mn: 0.1-1.5%, Zr: 0.02-0.2%, Cr: 0.02-0. 0.3%, contains one or more of the following, and the rest is
Al alloys with a composition consisting of inevitable impurities of Al have superior corrosion resistance and electrochemically less noble properties than pure Al such as 1070 and 1080 materials.
Therefore, when this Al alloy is used as the fin material of a heat exchanger, the excellent sacrificial anode effect protects the tube material from corrosion, and in combination with the excellent corrosion resistance of the fin material itself, It was discovered that the exchanger could be used for a significantly longer period of time. Therefore, this invention has been made based on the above knowledge, and the reason why the component composition is limited as described above will be explained below. (a) Sn The Sn component has the effect of electrochemically making the fin material less noble and exerting an excellent sacrificial anode effect on the pipe material, but its content is 0.02%.
If the content is less than 0.1%, the desired effect will not be obtained, and if the content exceeds 0.1%, not only will the effect not be further improved by the action, but the corrosion resistance will deteriorate. The amount was determined to be 0.02-0.1%. (b) Zn The Zn component has the effect of significantly improving the corrosion resistance of the fin material, but if the content is less than 0.04%, the desired excellent corrosion resistance cannot be secured, while if the content exceeds 0.09% Even if the Zn content is reduced to 0.04 to 0.09, not only will the effect of further improving corrosion resistance not be seen, but Zn evaporation during vacuum brazing will become significant and problems such as furnace contamination will occur. %. (c) Mn, Cr, and Zr These components have the effect of particularly improving high-temperature strength and further improving the sagging resistance of the fin material required during vacuum brazing, so they have particularly excellent resistance. It is included as necessary when drooping properties are required, but if the content is less than 0.1% Mn, less than 0.02% Cr, and less than 0.02% Zr, the desired high temperature strength improvement effect cannot be obtained. On the other hand, Mn: 1.5%, Cr:
Even if the content exceeds 0.3% and Zr: 0.2%, not only will no further high-temperature strength improvement effect appear, but also giant crystallized substances will be formed and workability will deteriorate. Therefore, the content is Mn: 0.1 ~
1.5%, Cr: 0.02~0.3%, and Zr: 0.02~0.2
%. Next, the fin material of the present invention will be specifically explained using examples. Example Al alloy 1 for fin materials of the present invention having the composition shown in Table 1 was prepared by a normal melting method.
~16, Comparative Al alloys 1 to 3 for fin materials, Al for pipe materials
Prepare molten alloy and Al alloy for brazing filler metal,
After casting, it was subjected to homogenization heat treatment, and then subjected to face milling and hot rolling to obtain a hot rolled plate with a thickness of 8 mm.
Next, a part of the hot-rolled sheets of Al alloys 1 to 16 for fin materials of the present invention and Al alloys 1 to 3 for comparison fin materials are cold-rolled to obtain a cold-rolled sheet of the present invention having a thickness of 0.2 mm. Fin materials 1-16 and comparison fin materials 1-
3 was manufactured. In addition, some of the above hot-rolled Al alloy sheets for pipe materials and hot-rolled sheets of Al alloy for brazing filler metal are cold-rolled to a thickness of 1 mm (hereinafter, the former is referred to as a thin sheet for pipe materials).

【table】

[Table] (referred to as a board). Next, the cold-rolled sheets of the Al alloy for brazing filler metal were superimposed on both sides of the remaining hot-rolled sheets of Al alloys 1 to 16 for fin materials of the present invention and Al alloys 1 to 3 for comparative fin materials, respectively. Composite fin materials 1 to 16 of the present invention and comparative composite fin materials 1 to 3 each having a plate thickness of 0.2 mm were manufactured by hot rolling to clad in this state and then cold rolling. Furthermore, regarding the remaining hot-rolled sheet of the Al alloy for pipe material, one side of the plate is for the brazing filler metal.
Cold-rolled plates of Al alloy were stacked together, hot-rolled to clad them in this state, and further cold-rolled to produce a composite thin plate for pipe material having a thickness of 1 mm. Next, the resulting fin materials of the present invention 1-
16, Comparative fin materials 1 to 3, Composite fin material 1 of the present invention
A test piece was cut out from each of Composite Fin Materials 1 to 16 and Comparative Composite Fin Materials 1 to 3, and the test piece was held in a vacuum at a temperature of 600°C for 10 minutes, then subjected to forced cooling heat treatment, and then a portion of it was The dissolution potential was measured while immersed in a 5.5% saline solution and an anode current of 1 mA/cm ² was applied, and the remaining test pieces were immersed in a saline solution adjusted to pH 3 for 20 hours. , the corrosion weight loss after the test was measured. In addition, the fin material dimensions of the present invention fin materials 1 to 16 and the comparative fin materials 1 to 3 and the composite thin plate for pipe materials, and the fin material dimensions of the present invention composite fin materials 1 to 16 and comparative composite fin materials 1 to 3 and the thin pipe material plate, respectively. :30mm×80
mm, thin plate for pipe material and composite thin plate dimensions: 50mm x 80mm
In this state, the fin material was assembled in an upright position along the longitudinal center line of the thin pipe material plate placed horizontally, and in this state, in a vacuum of 10 ^-4 torr, temperature: 600
Vacuum brazing was carried out under the conditions of holding at ℃ for 10 minutes, and a 500-hour CASS test was conducted on the test piece after vacuum brazing to measure the number of pitting corrosion and maximum pitting depth of the thin pipe plate or composite thin plate. The state of erosion of the fin material was observed. In addition, the corrosion state is marked ◎ for extremely light corrosion, and normal corrosion:
Evaluation was made with ○ mark, comparatively much corrosion: △ mark, marked corrosion: × mark, and case with little fin material remaining: XX marks. These results are shown in Table 2.

【table】

[Table] From the results shown in Table 2, the fin material 1 of the present invention
- 16 and composite fin materials 1 to 16 of the present invention all have excellent corrosion resistance and electrochemically abrasive properties, so they exhibit excellent sacrificial anode effects and can be used as pipe materials in a satisfactory state. In contrast, Comparative Fin Materials 1 to 3 and Comparative Composite Fin Materials 1 to 3 that did not contain Sn and/or Zn were inferior in at least one of corrosion resistance and sacrificial anode effect. It is clear that it has become a thing. As mentioned above, the fin material of the present invention has excellent corrosion resistance and also has an excellent sacrificial anode effect, so when it is put into practical use, it will protect the pipe material well from corrosion, so the fin material itself will be Coupled with its excellent corrosion resistance, it has industrially useful properties such as allowing heat exchangers to be used for an extremely long period of time.

Claims (1)

[Claims] 1. It is characterized by being composed of an Al alloy having a composition (weight %) containing 1 Sn: 0.02 to 0.1%, Zn: 0.04 to 0.09%, and the remainder consisting of Al and unavoidable impurities. Fin material for aluminum heat exchangers manufactured by vacuum brazing. 2 Contains Sn: 0.02 to 0.1%, Zn: 0.04 to 0.09%, and further contains one or two of the following: Mn: 0.1 to 1.5%, Zr: 0.02 to 0.2%, Cr: 0.02 to 0.3%. A fin material for an aluminum heat exchanger manufactured by vacuum brazing, characterized in that it is made of an Al alloy having a composition (the above weight %) containing the following and the remainder consisting of Al and unavoidable impurities.