JPS5825452A - Al alloy for fin material of heat exchanger with superior dropping resistance and sacrificial anode effect - Google Patents

Abstract

PURPOSE:To provide the titled alloy consisting of a prescribed percentage each of Zr and Si and the balance Al with inevitable impurities, showing superior dropping resistance during heating in a brazing stage, and preventing the corrosion of a tube material as the opposite member by the superior sacrificial anode effect. CONSTITUTION:This Al alloy for the fin material of a heat exchanger consists of, by weight 0.02-0.2% Zr, 0.2-1.0% Si and the balance Al with inevitable impurities or contains further 0.1-0.7% Mg. Since the Al alloy has superior dropping resistance and sacrificial anode effect, when it is used as the fin material of a heat exchanger made of Al alloy, the occurrence of fatigue and deformation during brazing is prevented. Accordingly, the heat exchanger can be manufactured in a high yield, and it shows superior corrosion resistance and can be used for over a long term.

Description

[Detailed Description of the Invention] This invention particularly provides that when used as a fin material for an At alloy heat exchanger, brazing such as vacuum brazing and flux brazing is excellent against heating during the process. The present invention relates to an M alloy that exhibits sagging resistance (deformation resistance) and, when put into practical use, has the property of effectively preventing corrosion of a mating member, a tube material, due to its excellent sacrificial anode effect.

Conventionally, M alloy heat exchangers have generally used a thin plate of AA-Mn alloy or A1. A plating sheet made of a Mn alloy core material clad with an AN-8i alloy brazing filler metal on one or both sides is prepared, while the tube material is made of, for example, pure A
Prepare a sheet made of A or At-Mn alloy, or a plating sheet made of pure M or Ae-Mn alloy core material clad with AA-8i alloy brazing material. However, it is manufactured by appropriately combining these two members and brazing them together. However, in manufacturing conventional At alloy heat exchangers manufactured in this way, brazing is not a process that significantly reduces the strength of the fin material due to high-temperature heating; 81 diffuses into the fin material and deteriorates its drooping resistance, which often causes the fin material to deform, making it impossible to properly braze the fin material to the pipe material. On the other hand, in practical use, Mn in the fin material has a significant electrochemical effect, so for example, if pure An-based pipe material is used, the pipe material may become attached to the fin material. In comparison, corrosion of the pipe material is accelerated because it is less noble, and as a result, through-holes are formed in the pipe material, and accidents often occur due to these through-holes.

Therefore, attempts have been 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 using the resulting sacrificial anode effect.
When vacuum brazing is applied during the manufacturing process, the Zn in the fin material evaporates during the vacuum brazing process, and the brazing process later contains enough Zn to make it electrochemically base compared to the pipe material. It was a funny thing.

From the viewpoints mentioned above, the present inventors have developed an AI that does not deform even when heated during brazing and has relatively less electrochemical properties than pipe materials! As a result of conducting research to obtain a fin material for an alloy heat exchanger, the fin material contained Zr: 0.02 to 0.2%, Si: 0.
Contains 2 to 1.0%, and further contains Mg: 0 as necessary.
．． When the fin material is composed of an At alloy having a composition (by weight %) containing 1 to 0.7% of Mn and the rest consisting of Al and unavoidable impurities, the fin material has a relatively low electrochemical performance because it does not contain Mn. It exhibits an excellent sacrificial anode effect on the pipe material and maintains excellent thermal conductivity, and due to the coexistence of Zr and Si, which are alloy components, brazing can be performed using a brazing material. Since the diffusion erosion into the fin material of 81 is significantly suppressed, it has excellent sagging resistance, and when the fin material further contains Mg, it has high strength. I gained the knowledge that it becomes what you have.

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

(a) Zr The Zr component forms fine AP particles during the intermediate annealing process in which cold rolling and intermediate annealing are heated to a temperature around 300 to 350°C. , -Zr compounds precipitate, and the AA-Zr compounds have the effect of significantly increasing the recrystallization temperature, so the crystal grains of the recrystallized grains become coarser, and as a result, the tube material and fin material Brazing sometimes suppresses the diffusion erosion of Si in the brazing filler metal to the fin material, thereby maintaining excellent sagging resistance, but its content is 0.02%. If the content is less than 0.2%, it will not be possible to secure the desired excellent sagging resistance, while if the content exceeds 0.2%, no further improvement will be achieved, and instead, giant crystals will be likely to form during melting and casting. Therefore, the content was set at 0.02 to 02%.

(b) 5i Si component has AP! - It has the effect of significantly accelerating the formation of Zr compounds and thereby improving the sagging resistance, but if the content is less than 0.2%, the desired effect cannot be obtained, whereas if it exceeds 1.0%. Even if it is contained, not only will it not produce any further improvement effect, but it will also have a tendency to become electrochemically detrimental, making it impossible to fully demonstrate the sacrificial anode effect. It was set at 1.0%.

(c) Mg The Mg component is solid-solved in the base material to strengthen it as a solid solution, and is work-hardened at a small processing rate during cold working after intermediate annealing during thin plate manufacturing to increase strength. Since it has the effect of significantly improving strength, it is included as necessary when particularly high strength is required, but if the content is less than 0.1%, the desired strength improvement effect cannot be obtained; If the content exceeds 0.05%, the recrystallized grain coarsening effect will be inhibited and the sagging resistance will deteriorate.
It was set at 1% to 0.7%.

Next, the A2 alloy of the present invention will be specifically explained by comparing it with an example and a conventional example.

Examples A9 alloys 1 to 4 of the present invention for fin materials having the final component compositions shown in Table 1 were prepared by a conventional melting method. Conventional Ae alloys for fin materials 1, 2. Ae gold alloy for pipe materials, b, and A9 alloy for brazing filler metal were melted and cast into ingots.

Although not shown in Table 1, these various APs
, alloy ingots all contain Mn: 0 as inevitable impurities.
．． 01% or less, Mg: 0.01% or less, cu: o,
o 5% or less, Zn:O, 02% or less.

Fe: 0.40% or less, and Cr: 0.01%
It contained the following:

Next, regarding the various above-mentioned M alloy ingots obtained as a result, AQ alloys 1 to 4 of the present invention. Conventional alloy l.

2. A9 alloys a and b for pipe materials are hot-rolled plate thickness: S
A hot-rolled plate of +Ot was used, and the superalloy for brazing metal was similarly hot-rolled and a hot-rolled plate with a thickness of 5rtat, and the hot-rolled plate of the A2 alloy for brazing metal was cold-rolled. Thickness:
It was made into a cold-rolled sheet of 1.

In this state, the present invention A1 alloy 1-4. Conventional M alloy 1.2
．． The cold-rolled plates of the A9 alloy for brazing filler metal are laminated on both sides of the hot-rolled plates of the AR gold alloy for pipe materials and b, and both sides are clad by hot rolling, and the At alloys 1 to 4 of the present invention
For the conventional A1 alloys 1 and 2 cladding materials, the plate thickness was set to 0.5 mm, while the AA alloys a and b for pipe materials were
, the plate thickness is 1 dragon, and the present invention ATL
A part of the clad material of Alloys 1 to 4 and conventional A1 Alloys 1 and 2 was cold rolled, and intermediate annealing was performed during this process to obtain a final plate thickness of 0.16 g with a cold rolling reduction of 40%. It was used as a praising sheet.

Moreover, on the other hand, the present invention At alloy 1 having the above plate thickness: 8 mm
~4. Conventional superalloys 1, 2. and Aε alloys a, b for pipe materials
The hot-rolled sheets of the A1 alloys 1 to 4 of the present invention and the conventional A2 alloy 1.2 have a thickness of 0.5B, and the hot-rolled sheets of the A9 alloy ab for pipe materials are , the plate thickness was set to 1 mm, and a part of the cold rolled plates of real tag alloy 4 and conventional superalloys 1 and 2 were continuously cold rolled, and intermediate annealing was performed in the middle to reduce the thickness to 40%. A thin plate having a cold rolling rate and a final plate thickness of O, 16B was obtained.

The plate thickness thus prepared: 0.16 m, and 0
．． 5@Il and conventional superalloys 1 and 2 and brazing superalloys (hereinafter referred to as plating sheets for fin materials of the present invention 4 and 4). Conventional brazing sheets for fin materials 1 and 2), brazing sheets for pipe materials which are clad materials of superalloys a and b for pipe materials having a plate thickness of 1 and A1 alloy for brazing filler metals) a, -b, and Above board thickness:
0.16 and 0-511+1 b The thin plates 1 to 4 for fin materials of the present invention and the thin plates 1, 2 for conventional fin materials. Among the thin plates a and b for pipe materials having a thickness of 1, the plating sheets 1 to 4 for fin materials of the present invention and the conventional plating sheet 1 for fin materials of the present invention have thicknesses of O, 16, ... ,2. Furthermore, using a test piece having dimensions of width: 3011 x length: 14 o IH cut out from the thin plate 1-4 for fin material of the present invention and the conventional thin plate for fin material of the same 0.1611, Length direction - blade end 3
A drooping resistance test was conducted under the condition that the specimen was held horizontally at 2,620° C. for 5 minutes, and the height of drooping at the tip of the test piece after heating was measured. This measurement result is
Shown in the table.

As shown in Table 2, the plating sheet 4 for fin materials of the present invention and the thin plates 1 to 4 for fin materials of the present invention both exhibit excellent droop resistance, and brazing sometimes causes "sagging". This shows that there is almost no occurrence of deformation or deformation, indicating that good brazing is possible, whereas conventional plating sheets for fin materials l.

2 and the conventional thin plates 1 and 2 for fin materials have poor droop resistance.

Next, plating sheets 1 to 4 for fin materials of the present invention and conventional plating sheets 1, 2 for Z-in materials having the above-mentioned plate thickness of 0.5I+1m were prepared. Furthermore, test pieces for fin materials having a width of 4 o 1 RH x length of near 0 mm were cut out from the thin plates 1 to 4 for fin materials of the present invention having a plate thickness of 20.51 m and the thin plates 1 and 2 for conventional fin materials. :1 plating sheet for pipe material a.

b, and the width from the pipe material thin plates a and b of I IIN:
Table 2 A tube material test piece having dimensions of 5011 In this case, either the fin material test piece or the tube material test piece is combined with a brazing sheet clad with a brazing material), and in this state, brazing is performed in a vacuum at a temperature of 620°C for 5 minutes. , 10 p, p, B of Cu
It was subjected to a tap water immersion test in which it was immersed in tap water at 40°C to which ions had been added for 30 days, and a CASS test for 30 days.

After these tests, the number of pitting corrosion and the maximum pitting depth in the above tube material test pieces were measured, and the measurement results are shown in Table 3.

As shown in Table 3, plating sheets 1 to 4 for fin materials of the present invention and thin plates 1 to 4 for fin materials of the present invention are as follows:
Both of them fully exhibit the sacrificial anode effect, so corrosion of the mating materials, thin plate for pipes (Al BL) and brazing seams for pipes (a) and b), is suppressed to a minimum, whereas conventional fin material plating sheets 1 and 2 and the conventional thin plates 1 and 2 for fin materials, it is clear that corrosion of the mating material is accelerated because these are chemically harmful to the metal.

As mentioned above, the Affiff of this invention has excellent droop resistance and sacrificial anode effect, so it can be used as At
When used as a fin material for an alloy heat exchanger, brazing can produce heat exchangers with a higher yield without causing "deformation" or deformation, and the resulting heat The exchanger has excellent corrosion resistance and has industrially useful properties such as being able to be used for a long period of time.

Applicant: Mitsubishi Aluminum Corporation Agent Tomi 1) Kazuo

Claims (2)

[Claims] (1) Zr: 0.02-0.2%, Si:
0.2-1. An M alloy for heat exchanger fin material having excellent sagging resistance and sacrificial anode effect, characterized by containing Oqb and the remainder consisting of At and unavoidable impurities (weight percent). (2) Zr: 0.02-0.2%, Si:
Contains 0.2 to 1.0%, and further contains Mg: O, l
An At alloy for heat exchanger fin material having excellent sagging resistance and sacrificial anode effect, characterized in that it contains -0.7% and the remainder consists of At and unavoidable impurities (weight percent).