JPH028018B2 - - Google Patents

Description

[Detailed description of the invention]

This invention exhibits excellent sagging resistance (deformation resistance) against heating during brazing processes such as vacuum brazing and flux brazing in the manufacture of Al alloy heat exchangers. The present invention relates to a heat exchanger fin material that exhibits an anode effect and has the property of effectively preventing corrosion of the tube material that is the mating member. Conventionally, Al alloy heat exchangers are generally made of, for example,
A fin material made of a thin sheet of Al-Mn alloy, or a brazing sheet made by cladding an Al-Si alloy filler metal on one or both sides of the thin sheet, is made of, for example, pure Al or Al-Mn alloy. Alternatively, it is manufactured by cladding the surface of this material with an Al--Si alloy brazing material and brazing it to a tube material that becomes a brazing sheet. However, in manufacturing the above-mentioned conventional Al alloy heat exchanger, not only does the strength of the fin material decrease significantly due to the high temperature heating during brazing, but also the Si in the brazing material As a result, the fin material becomes deformed due to diffusion erosion, which deteriorates the sag resistance.As a result, the problem often arises that the fin material cannot be properly brazed to the pipe material. In this case, Mn in the fin material has the effect of making it electrochemically highly noble, so if pure Al-based pipe material is used, for example, the pipe material will be less noble than the fin material. As a result, corrosion of the pipe material is accelerated, and as a result, through holes are formed in the pipe material, and accidents often occur due to these through holes. Therefore, an attempt was made to make the fin material electrochemically less noble than the pipe material by incorporating Zn into the fin material, and to prevent corrosion of the pipe material by the resulting sacrificial anode effect. When vacuum brazing is applied, the Zn in the fin material evaporates during the vacuum brazing process, and after brazing, enough Zn to make it electrochemically base compared to the pipe material is removed.
was not left in the fin material and did not solve any problems. From the above-mentioned viewpoints, the present inventors have developed an Al alloy heat exchanger that does not deform when heated during brazing and has relatively less electrochemical properties than pipe materials. As a result of research to obtain fin materials for vessels, we found that fin materials made of thin plates, or made into brazing sheets by cladding Al-Si alloy brazing metal on one or both sides of the thin plates, were found to be The plate material contains Zr: 0.02 to 0.2%, Si: 0.2 to 1%, in weight% (hereinafter % is shown in weight%),
The remainder consists of Al and unavoidable impurities.
When composed of Al alloy, the resulting fin material is
Because it does not contain Mn, it does not become electrochemically noble, so it exhibits an excellent sacrificial anode effect on the pipe material and maintains excellent thermal conductivity. We obtained the knowledge that coexistence with Si significantly suppresses the diffusion of Si in the filler metal into the fin material during brazing, resulting in excellent sagging resistance. It was. This invention has been made based on the above knowledge, and the reason why the composition of the Al alloy constituting the thin plate material of the fin material is limited as described above will be explained below. (a) Zr The Zr component is produced by fine Al during the intermediate annealing process of repeated cold rolling and intermediate annealing heated to a temperature around 300 to 350°C during the production of the thin plate material constituting the fin material. -This Al-Zr compound precipitates as a Zr compound, and since this Al-Zr compound has the effect of significantly increasing the recrystallization temperature, the crystal grains become coarser after recrystallization, and as a result, the brazing between the pipe material and the fin material Occasionally, the diffusion erosion of Si in the filler metal to the filler metal is suppressed, which has the effect of maintaining excellent sagging resistance, but if the content is less than 0.02%, the desired excellent Sagging resistance cannot be ensured, and on the other hand, even if the content exceeds 0.2%, no further improvement effect appears, and instead, it becomes easier to form giant crystals during melting and casting, impairing workability. Therefore, its content is 0.02 to 0.2
%. (b) Si The Si component has the effect of significantly promoting the formation of Al-Zr compounds and thereby improving the sagging resistance of the fin material, but if its content is less than 0.2%, the desired effect is not achieved. On the other hand, even if the content exceeds 1%, not only will no further improvement effect appear, but there will also be a tendency to become electrochemically noble, making it impossible to fully demonstrate the sacrificial anode effect. , its content is 0.2~1
%. Next, the heat exchanger fin material of the present invention will be specifically explained using examples. By an ordinary melting method, Al alloys 1 to 4 of the present invention for fin materials, conventional Al alloys 1 and 2 for fin materials, Al alloys a and b for pipe materials, and a brazing material, each having the final component composition shown in Table 1, were prepared. Al alloy for materials was melted and cast into ingots. Although not shown in Table 1, these various Al alloy ingots are

【table】

[Table] In both cases, Mn: 0.01% or less,
Mg: 0.01% or less, Cu: 0.05% or less, Zn: 0.02%
Below, Fe: 0.40% or less and Cr: 0.01% or less were contained. Next, regarding the various Al alloy ingots obtained as a result, the present invention Al alloys 1 to 4 for fin materials,
Conventional alloys 1 and 2 for fin materials, Al alloy a for pipe materials,
b is a hot-rolled plate with a thickness of 8 mm by hot rolling, and the Al alloy for brazing metal is similarly hot-rolled into a hot-rolled plate with a thickness of 5 mm;
The hot-rolled alloy sheet was cold-rolled to obtain a cold-rolled sheet with a thickness of 1 mm. In this state, on both sides of the hot-rolled sheets of Al alloys 1 to 4 for fin materials, conventional Al alloys 1 and 2 for fin materials, and Al alloys a and b for pipe materials,
Al alloy cold-rolled plates are stacked together and hot rolled to clad both sides to form a brazing sheet, resulting in a plate thickness of 0.5mm (Thickness of thin plate: 0.4mm, thickness of one side of brazing metal: 0.05mm) Brazing filler metal cladding fin materials 1 to 4 of the present invention, conventional brazing filler metal cladding fin materials 1 and 2, and brazing filler metal cladding pipe materials a and b each having a plate thickness of 1 mm were manufactured. Furthermore, the above-mentioned brazing filler metal cladding fin materials 1 to 4 of the present invention and conventional brazing filler metal cladding fin materials 1 and 2
A part of the steel sheet was cold rolled, and intermediate annealing was performed during this process to achieve a final rolling reduction of 40%, resulting in a plate thickness of 0.16 mm. On the other hand, the above-mentioned Al alloys 1 to 4 for fin materials having a plate thickness of 8 mm, conventional Al alloy 1 for fin materials,
2, and the thin plate fin materials 1 to 4 of the present invention having a thickness of 0.5 mm and the conventional thin plate fin materials 1 by cold rolling the hot rolled sheets of Al alloys a and b for pipe materials.
2, and thin plate tube materials a and b having a plate thickness of 1 mm were manufactured, and the above-mentioned thin plate fin materials 1 to 4 of the present invention and conventional thin plate fin materials 1 and 2 were continuously subjected to cold rolling. After intermediate annealing, the final rolling reduction is 40.
The plate thickness was set as 0.16 mm as a percentage. Next, the thickness of each plate prepared in this way:
Brazing filler metal clad fin material 1 of the present invention having a diameter of 0.16 mm
~4, and conventional brazing filler metal clad fin material 1,
2. Furthermore, using test pieces cut out from thin plate fin materials 1 to 4 of the present invention and conventional thin plate fin materials 1 and 2 and having dimensions of width: 30 mm x length: 140 mm, the length of this test piece was determined. One end in the horizontal direction 30
A drooping resistance test was conducted under the condition that the specimen was held at a temperature of 620° C. for 5 minutes with the specimen horizontally fixed, and the height of drooping at the tip of the test piece after heating was measured. The measurement results are shown in Table 2. From the results shown in Table 2, the brazing filler metal clad fin materials 1 to 4 of the present invention and the thin plate fin materials 1 to 4 of the present invention both exhibit excellent sagging resistance and are free from "sagging" or deformation during brazing. This shows that good brazing is possible with almost no brazing, whereas it is clear that conventional brazing filler metal clad fin materials 1 and 2 and conventional thin plate fin materials 1 and 2 only show poor sagging resistance. It is. In addition, the brazing filler metal clad fin materials 1 to 4 of the present invention, all of which have a plate thickness of 0.5 mm, the conventional brazing filler metal clad fin materials 1 and 2, and the thin plate fin materials 1 to 4 of the present invention, each having a plate thickness of 0.5 mm.
4, and conventional thin plate fin materials 1 and 2,

【table】

[Table] Width: 40 mm x length: 70 mm test pieces were cut out, and from the brazing metal clad pipe materials a, b and thin plate pipe materials a, b with plate thickness: 1 mm, width: 50 mm x length: 70 mm.
Cut out a test piece with a dimension of In this state, brazing was performed in a vacuum at a temperature of 620°C for 5 minutes, and immersed in tap water at 40°C with 10ppm of Cu ⁺⁺ ions added for 30 days. Tap water immersion test and 30 days
Subjected to CASS test. After these tests, the number of pitting corrosion and the maximum pitting depth in the tube test pieces were measured, and the measurement results are shown in Table 3. From the results shown in Table 3, it can be seen that the brazing filler metal fin materials 1 to 4 of the present invention and the thin plate fin materials 1 to 4 of the present invention fully exhibit the sacrificial anode effect, and therefore the thin plate tube material that is the mating member Corrosion of a, b and brazing metal clad pipe materials a, b is suppressed to a minimum, whereas conventional brazing filler metal clad fin materials 1 and 2 and conventional thin plate fin materials 1 and 2 are susceptible to electrochemical damage. It is clear that corrosion of the pipe material, which is the mating member, is accelerated.

【table】

[Table] As mentioned above, the heat exchanger fin material of the present invention has excellent sag resistance and sacrificial anode effect, so it can be used without "sagging" or deformation during brazing.
Therefore, a heat exchanger can be manufactured with a high yield, and the resulting heat exchanger has excellent corrosion resistance and has industrially useful properties such as being able to be used for a long period of time.

Claims (1)

[Claims] 1 Contains Zr: 0.02 to 0.2%, Si: 0.2 to 1%,
A heat exchanger fin material having excellent sag resistance and sacrificial anode effect, characterized by being made of a thin plate material of an Al alloy having a composition (by weight % or more) of Al and unavoidable impurities. 2 Contains Zr: 0.02 to 0.2%, Si: 0.2 to 1%,
A droop-resistant brazing sheet characterized in that a brazing sheet is made by cladding an Al-Si alloy brazing material on one or both sides of an Al alloy thin plate material whose composition (weight percent) consists of Al and unavoidable impurities. Heat exchanger fin material with excellent performance and sacrificial anode effect.