JPH0333770B2 - - Google Patents

Description

[Detailed description of the invention]

When manufacturing a heat exchanger by brazing a fin material and a tube material, the present invention provides for a heat exchanger that has high temperature strength that exhibits excellent sagging resistance against heating during brazing, and that the tube material after brazing The present invention relates to a composite fin material made of Al alloy for heat exchangers that exhibits an excellent sacrificial anode effect against heat exchangers. In general, Al alloys are light and have excellent thermal conductivity.
Since it also has excellent corrosion resistance, it is widely used, for example, in the manufacture of heat exchangers such as automobile radiators. This heat exchanger is, for example, Al-
Mn-based alloy is used as the core material, and one side of this core material is made of Al-Si.
A pipe material made of a brazing sheet made of brazing material of a brazing alloy and a fin material of an Al-Mn alloy are combined, and this combination is brazed in a vacuum or in an inert gas without flux. or by brazing with flux in a low-pressure atmosphere. Therefore, it goes without saying that the fin material of a heat exchanger is required to have sufficient sagging resistance, that is, high-temperature strength, so as not to deform when heated above the melting temperature of the filler metal during brazing. In practical use, it is required that the sacrificial anode exhibit a sufficiently satisfactory sacrificial anode effect on the pipe material. However, the above-mentioned Al--Mn alloy fin material is not electrochemically sufficiently base with respect to the tube material, so it cannot be expected to exhibit a satisfactory sacrificial anode effect. From this point of view, as a fin material for heat exchangers,
The Al-Mn alloy is made electrochemically less noble by containing about 1 to 2% Zn, thereby fully exhibiting the sacrificial anode effect on the pipe material.
−Zn-based alloy was proposed, and it is true that this Al−Mn−
Zn-based alloy fin materials exhibited excellent sacrificial anode effects when the heat exchanger was manufactured by brazing in an inert gas atmosphere or in the air, but had poor high-temperature strength. Furthermore, when a heat exchanger is manufactured using this material by brazing in a vacuum, the Zn content is high,
In addition, since Zn has a high vapor pressure, a large amount of Zn in the fin material evaporates during brazing, and the remaining amount becomes small, resulting in a low sacrificial anode effect on the tube material, and the possibility of furnace contamination due to Zn evaporation. Such problems would arise. Therefore, from the above-mentioned viewpoint, the present inventors recognized that it would be extremely difficult to construct a fin material with high-temperature strength and sacrificial anode effect from a single material. As a result of conducting research to ensure this by constructing the heat exchanger fin material with composite materials, we found that the heat exchanger fin material has the following properties in weight% (hereinafter % indicates weight%): Mn: 0.1 to 1.5%, Zn: 0.01 to 0.5%, and if necessary, one or more of the following: Mg: 0.01-1%, Cu: 0.01-0.2%, Mn: 0.02-0.2%, Cr: 0.02-0.3%. contains and the rest is
Both sides of the Al alloy core material, which has a composition consisting of Al and inevitable impurities, contain In: 0.01 to 0.1%, Zn: 0.01 to 0.3%, and if necessary, Mg: 0.01 to 1%. When constructed from an Al alloy composite material made by cladding an Al alloy skin material with a composition that contains aluminum and unavoidable impurities, the core material provides excellent sagging resistance (high temperature strength). Since Zn content is relatively low in the above-mentioned skin material, evaporation of Zn during vacuum brazing is suppressed as much as possible, and coexistence with In allows sufficient electrochemical performance. From being lowly,
They discovered that this skin material ensures an excellent sacrificial anode effect. This invention has been made based on the above findings, and the reason why the component compositions of the core material and the skin material are limited as described above will be explained below. A Core material (a) Mn The Mn component forms a compound with Al, finely disperses and precipitates in the base material, and significantly increases the recrystallization temperature of the alloy, resulting in coarsening of recrystallized grains during brazing heating. , has the effect of improving the sagging resistance (high temperature strength) during brazing, but if the content is less than 0.1%, the desired effect cannot be obtained; on the other hand, if the content exceeds 1.5%, Not only would it not be possible to obtain further improvement effects, but also the processability would be impaired by the formation of giant crystals during melting and casting, and the thermal conductivity would also decrease, so the content was reduced to 0.1. It was set at ~1.5%. (b) Zn The Zn component in the core material is included for the purpose of replenishing the small amount of Zn that evaporates from the skin material in response to the vacuum brazing heat. Therefore, if the content is less than 0.01%, It is not possible to satisfactorily replenish Zn to the skin material during brazing heating, and on the other hand, if the content exceeds 0.5%, a large amount of Zn will evaporate through the skin material.
Its content was set at 0.01-0.5%. (c) Mg and Cu These components dissolve in solid solution in the base material and have the effect of strengthening it, so they are included as necessary when particularly strong strength is required, but the content is If Mg is less than 0.01% and Cu is less than 0.01%, the desired strength improvement effect cannot be obtained, whereas if Mg is contained in excess of 1%, the sagging resistance (high temperature strength) will be significantly reduced, and Cu If the content exceeds 0.2%, the content becomes extremely electrochemically noble and the sacrificial anode effect on the pipe material is lost.
Mg: 0.01-1%, Cu: 0.01-0.2%. (d) Zr and Cr When these components coexist with Mn, they form a compound with Al and are finely dispersed and precipitated in the matrix, further increasing the recrystallization temperature of the alloy and causing it to become weak during brazing heating. Since it has the effect of coarsening recrystallized grains and improving sagging resistance, it is included as necessary especially when even higher sagging resistance is required, but the content is Zr: 0.02%. Less than and Cr: 0.02
If the content is less than 0.3%, the desired sagging resistance improvement effect cannot be obtained, while if the content exceeds 0.3% Cr and 0.2% Zr, it becomes easier to form giant crystals during melting, reducing workability. , and no further improvement effect due to sagging resistance appears, so the content was reduced to Zr: 0.02 to 0.2%,
Cr: set at 0.02 to 0.3%. B Skin material (a) In and Zn When both components coexist,
It has the effect of electrochemically making the skin less base and giving it an excellent sacrificial anode effect, as well as improving its corrosion resistance. Therefore, even if the In content is less than 0.01%, Zn
Even if the content of In is less than 0.01%, excellent sacrificial anode effect and corrosion resistance cannot be ensured. On the other hand, In: 0.1% and Zn: 0.3
If the content exceeds 0.01% to 0.1%, the desired effect of improving the above-mentioned action will not be obtained, and the processability will deteriorate. It was set at 0.3%. (b) Mg The Mg component has the effect of improving the corrosion resistance of the skin material without substantially changing the electrochemical properties of the skin material, so it may be included as necessary when particularly corrosion resistance is required. If the content is less than 0.01%, the desired effect of improving corrosion resistance cannot be obtained, while if the content exceeds 1%, not only the further improvement effect cannot be obtained, but also the workability deteriorates. Therefore, its content was determined to be 0.01 to 1%. Next, the composite fin material of the present invention will be specifically explained using examples. Example Al alloy for core material and Al alloy for skin material having the final component compositions shown in Table 1, respectively, by ordinary melting method.
After melting and casting Al alloys into ingots, homogenization treatment is performed under normal conditions, and then these Al alloys are
Among the alloy ingots, the Al alloy for the core material was hot-rolled under normal conditions to form a hot-rolled plate with a thickness of 8 mm, and the Al alloy for the skin material was also hot-rolled under normal conditions. A hot-rolled plate with a plate thickness of 5 mm is obtained, and then cold-rolled to produce a cold-rolled plate with a plate thickness of 1 mm.
Next, in the combination shown in Table 1, the Al alloy hot-rolled sheet for the core material having a thickness of 8 mm and the cold-rolled Al alloy sheet for the skin material having a sheet thickness of 1 mm were combined as shown in Table 1. The cold-rolled aluminum alloy sheets for skin material are superimposed on both sides of the hot-rolled aluminum alloy sheet for materials, and the superposed body is hot-rolled under normal conditions to form a plate with a thickness of 3 mm, Subsequently, this is subjected to cold rolling while appropriately performing intermediate annealing (final cold working rate:
30%) to produce two types of Al alloy composite fin materials 1 to 27 of the present invention having plate thicknesses of 0.5 mm and 0.16 mm, respectively. In addition, for the purpose of comparison, an Al alloy having the final component composition shown in Table 1 was melted and cast.
After homogenization, it is hot rolled under normal conditions to obtain a hot rolled sheet with a thickness of 5 mm, and then rolled as appropriate.

【table】

[Table] Two types of conventional Al alloy fin materials having plate thicknesses of 0.5 mm and 0.16 mm were manufactured by cold rolling (final cold working ratio: 30%) while adding intermediate annealing. Next, a drooping resistance test was conducted for the purpose of evaluating high temperature strength using the composite fin materials 1 to 27 made of Al alloy of the present invention and the conventional fin material made of Al alloy having a plate thickness of 0.16 mm. For the sagging resistance test, as a specimen,
Using a specimen with dimensions of width: 30 mm x length: 140 mm, the specimen was held horizontally at a distance of 30 mm from one end in the longitudinal direction, in a vacuum of approximately 10 ^-4 torr, at a temperature of 620°C. The hanging height of the tip was measured under the condition of holding for 5 minutes. Further, using the specimens after the sagging resistance test, the potential for pitting corrosion in 1N saline (saturated calomel standard) was measured for the purpose of evaluating the sacrificial anode effect. Furthermore, specimens with dimensions of width: 20 mm x length: 50 mm were cut out from the above-mentioned composite fin materials 1 to 27 made of Al alloy of the present invention with a thickness of 0.5 mm and conventional fin materials made of Al alloy. Separately prepared width: 40mm x
Length: 50mm x plate thickness: 1mm, Mn:
Si: 9.50 on one side of the core material, thickness: 0.9 mm, with a composition consisting of 1.21%, Al and the remainder: unavoidable impurities
%, Mg: 1.53%, Al and unavoidable impurities: the remainder, the brazing filler metal is clad with a thickness of 0.1 mm, and is placed on the longitudinal center line of an Al alloy plate, which is normally used as a pipe material. Hold it upright at a right angle, in this state, in vacuum, temperature: 620
The brazing process was performed under the condition of holding at ℃ for 5 minutes, and the resulting assembly after brazing had a concentration of 1 ppm.
Temperature of Cu ⁺⁺ ion content: 30°C in tap water at 40°C
Tap water immersion test for 1 day and 30 day immersion test
A CASS test was conducted to measure the number of occurrences of pitting corrosion and the maximum depth of pitting corrosion in the Al alloy plate material commonly used as a pipe material after the test. These measurement results are also shown in Table 1. From the results shown in Table 1, it is clear that the present Al alloy composite fin material 5 with almost the same Mn content and the conventional Al alloy composite fin material 5 have almost the same Mn content.
As is clear from the comparison with the alloy fin materials, the Al alloy composite fin materials 1 to 27 of the present invention all have excellent sagging resistance (high temperature strength) equivalent to the conventional Al alloy fin materials, On the other hand, regarding the sacrificial anode effect, it shows much better results than conventional Al alloy fin materials. The various Al alloys shown in Table 1 all contain Mn: 0.01% or less as unavoidable impurities.
It contained Cu: 0.01% or less, Cr: 0.01% or less, Zr: 0.01% or less, Si: 0.3% or less, and Fe: 0.4% or less. As mentioned above, the Al alloy composite fin material of the present invention has excellent high-temperature strength (sag resistance), so it does not cause "settling" in the brazing process applied when manufacturing heat exchangers. Not only does brazing not occur, and therefore good brazing can be performed, it also has electrical properties that are electrochemically sufficiently base to the pipe material to be brazed. In addition to exhibiting a sufficient sacrificial anode effect and having excellent corrosion resistance, it has industrially useful properties such as making it possible to significantly extend the life of heat exchangers.

Claims (1)

[Claims] 1. On both sides of an Al alloy core material containing Mn: 0.1 to 1.5%, Zn: 0.01 to 0.5%, and the remainder consisting of Al and inevitable impurities, In: 0.01 to 0.1 %, Zn: 0.01 to 0.3%, and the remainder is Al and unavoidable impurities (weight %).The heat exchanger has excellent high-temperature strength and sacrificial anode effect. Composite fin material made of dexterous Al alloy. 2 Contains Mn: 0.1 to 1.5%, Zn: 0.01 to 0.5%, and further contains one or two of the following: Mg: 0.01 to 1%, Cu: 0.01 to 0.2%, and the remainder is Al. Both sides of an Al alloy core material having a composition consisting of This is an Al alloy composite fin material for heat exchangers, which is made by cladding an Al alloy skin material and has excellent high-temperature strength and sacrificial anode effect. 3 Contains Mn: 0.1 to 1.5%, Zn: 0.01 to 0.5%, and further contains one or two of the following: Zr: 0.02 to 0.2%, Cr: 0.02 to 0.3%, and the rest is Al. Both sides of an Al alloy core material with a composition consisting of inevitable impurities contain In: 0.01 to 0.1%, Zn: 0.01 to 0.3%, and the remainder consists of Al and inevitable impurities (weight %). Al alloy composite fin material for heat exchangers with excellent high temperature strength and sacrificial anode effect, made by cladding Al alloy skin material. 4 Contains Mn: 0.1 to 1.5%, Zn: 0.01 to 0.5%, and further contains one or two of Mg: 0.01 to 1%, Cu: 0.01 to 0.2%, and Zr: 0.02 to 0.2. %, Cr: 0.02-0.3%, In: 0.01-0.1%, Zn: An Al alloy for heat exchangers with excellent high-temperature strength and sacrificial anode effect, which is made by cladding Al alloy skin material with a composition of 0.01 to 0.3% and the remainder consisting of Al and unavoidable impurities (weight percent). Composite fin material. 5 Mn: 0.1~1.5%, Zn: 0.01~0.5%, In: 0.01~0.1%, Zn: 0.01~ 0.3%, Mg: 0.01~1%, and the remainder is Al and unavoidable impurities (weight%).Thermal material has excellent high-temperature strength and sacrificial anode effect. Al alloy composite fin material for exchangers. 6 Contains Mn: 0.1 to 1.5%, Zn: 0.01 to 0.5%, and further contains one or two of the following: Mg: 0.01 to 1%, Cu: 0.01 to 0.2%, and the remainder is Al. Both sides of the Al alloy core material, which has a composition consisting of An Al alloy composite fin material for heat exchangers with excellent high-temperature strength and sacrificial anode effect, which is made by cladding an Al alloy skin material having the following composition (weight %). 7 Contains Mn: 0.1 to 1.5%, Zn: 0.01 to 0.5%, and further contains one or two of the following: Zr: 0.02 to 0.2%, Cr: 0.02 to 0.3%, and the rest is Al. In: 0.01-0.1%, Zn: 0.01-0.3%, Mg: 0.01-1%, on both sides of an Al alloy core material having a composition consisting of unavoidable impurities, with the remainder consisting of Al and unavoidable impurities. An Al alloy composite fin material for a heat exchanger, which has excellent high-temperature strength and sacrificial anode effect, and is made by cladding an Al alloy skin material having a weight percentage of (more than 1% by weight). 8 Contains Mn: 0.1 to 1.5%, Zn: 0.01 to 0.5%, and further contains one or two of Mg: 0.01 to 1%, Cu: 0.01 to 0.2%, and Zr: 0.02 to 0.2. %, Cr: 0.02-0.3%, In: 0.01-0.1%, Zn: 0.01~0.3%, Mg: 0.01~1%, and the rest is Al and unavoidable impurities (wt%).It has excellent high-temperature strength and sacrificial anode effect. Al alloy composite fin material for heat exchangers.