JPH05305307A - Manufacture of high strength aluminum alloy clad fin stock for heat exchanger - Google Patents

Abstract

PURPOSE:To provide a method for inexpensively manufacturing Al alloy clad fin stocks having high temperature buckling resistance and high strength after brazing. CONSTITUTION:Homogenization treatment of the specified Al-Mn-Si Al base alloy ingot is executed at the temperature of 400-560 deg.C, and the ingot is heated at the temperature of 400-560 deg.C to start hot rolling, and after hot rolling is completed at the temperature of 300 deg.C or lower, cold rolling is executed at the draft of 40% or less. After annealing at the temperature between 180 deg.C-240 deg.C, the cold finish rolling is further executed at the draft of 5-50%.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a fin material used in a heat exchanger made of an aluminum alloy, and in particular, a fin material is brazed to a passage material (tubular material or profile) for cooling water or a working fluid. The present invention relates to a method for manufacturing an aluminum alloy fin material which exhibits excellent high temperature buckling resistance against heating during brazing when assembling an exchanger and has high strength after brazing.

[0002]

2. Description of the Related Art In radiators for automobiles, air conditioners, heat exchangers such as intercoolers and oil coolers, Al--Cu alloys, Al--Mn alloys, Al--Mn alloys are used.
A working fluid passage constituent material such as a Cu-based alloy and a fin material of an aluminum alloy are assembled by brazing. The fin material is not deformed by this heating because its strength is significantly reduced and deformed by high temperature heating during brazing, or Si in the brazing material is diffused and buckled in the fin material. Therefore, excellent high temperature buckling resistance is required. Therefore, as the aluminum alloy fin material, an Al-Mn-based alloy has been conventionally used, and it has been proposed that various elements are added to this in order to further add the above characteristics. For example, it has been proposed that Zn, Sn, or the like is added to make it electrochemically base. However, when an element such as Sn or Zn is contained, the brazing property (high temperature buckling property) tends to be poor, so
For example, alloy ingots in which Mg, Mn, and Fe are adjusted in addition to Sn and Zn are heated, hot-rolled, and cold-rolled at 70% or more, and after the softening treatment, cold-rolled finish is 15 to 30%. Method (JP-A-58-31070), Sn, Z
An alloy ingot in which Mg, Mn, Fe, Si, and Zr are adjusted in addition to n is heated, hot-rolled, and cold-rolled to 70% or more, and after the softening treatment, cold-rolled finish is 15 to 30%. A method (JP-A-60-215729) and the like have been proposed. In these, annealing (softening) is 300-450 ° C.
It is said that it is important from the viewpoint of brazability.

[0003]

With respect to the Al—Mn alloy fin material that has been used or proposed in the related art, recently, in addition to weight reduction, there is a strong demand for cost reduction and the like. To make it thinner,
Inexpensive materials are required.

However, when the fin material as described above is manufactured by the conventional method, the tensile strength after brazing is 100M.
When the pressure becomes about Pa and the wall thickness becomes thin, there is a problem that fin collapse easily occurs due to insufficient strength.

The present inventors have found that as a fin material having a high strength after brazing, Al-Fe-Si-Mn-Mg-based alloys with In,
An alloy containing Sn, Ga, etc. has been proposed (JP-A-2-248704). There is another similar proposal (JP-A-3-20436). These have made it possible to reduce the wall thickness to some extent, but it is necessary to further increase the strength after brazing in order to further reduce the wall thickness.

An object of the present invention is to provide a method for inexpensively producing an aluminum alloy fin material having excellent high temperature buckling resistance and high strength after brazing.

[0007]

The present inventors have found that Al-M
As a result of various studies on the composition, manufacturing conditions, strength, high temperature buckling property, and formability of n-based alloys, as a result, it was found that the workability before annealing was not less than a predetermined amount and the annealing temperature before final cold rolling was extremely high. It was found that a fin material having high strength after brazing can be obtained by precipitating a fine compound on a worked structure at a very low temperature. In addition, it is possible to combine strength after brazing and high temperature buckling resistance by maintaining the homogenization conditions of the ingot, the heating temperature and end temperature of hot rolling, and the workability of final cold rolling appropriately. Heading, completed the present invention.

That is, according to the present invention, (1) Mn: 0.5 to 2.2% (weight%, the same applies hereinafter),
Si: An ingot of an alloy containing more than 0.35% and 1.2% or less with the balance being inevitable impurities and Al
After homogenizing at 560 ° C., heating to 400 to 560 ° C. to start hot rolling, and finishing hot rolling at 300 ° C. or less, cold rolling is performed at a reduction rate of 40% or more, and 180 ℃
After annealing at more than 240 ° C., further 5 to 50%
For producing a high-strength aluminum alloy fin material for heat exchangers, which performs cold finish rolling at a reduction ratio of.

(2) In the manufacturing method of the above (1), the alloy composition contains Mn: 0.5 to 2.2%, Si: more than 0.35% and 1.2% or less, and Zn: 0.5 ~
3.0%, Sn: 0.01 to 0.1%, In: 0.00
An alloy containing one or more selected from the group of 5 to 0.1% and Ga: 0.010.2%, with the balance being unavoidable impurities and Al.

(3) In the manufacturing method of the above (1), the composition of the alloy contains Mn: 0.5 to 2.2%, Si: more than 0.35% and not more than 1.2%, and further Zn: 0. .5-3.
0%, Sn: 0.01-0.1%, In: 0.005-
0.1%, one or more selected from the group of Ga: 0.01 to 0.2%, and Zr: 0.25% or less, C
r: An alloy containing one or two selected from the group of 0.25% or less and the balance being unavoidable impurities and Al.

(4) In the manufacturing method of the above (1), the composition of the alloy contains Mn: 0.5 to 2.2%, Si: more than 0.35% and not more than 1.2%, and further Zn: 0. .5-3.
0%, Sn: 0.01-0.1%, In: 0.005-
0.1%, Ga: 0.01 to 0.2%, one or more selected from the group, Zr: 0.25% or less, Cr:
1 type and 2 types selected from the group of 0.25% or less, and M
g: 0.05 to 1.0%, Cu: 0.3% or less, Fe:
An alloy containing one or more selected from the group of 0.1 to 0.6% and the balance being unavoidable impurities and Al.

(5) In the manufacturing method of the above (1), the composition of the alloy contains Mn: 0.5 to 2.2%, Si: more than 0.35% and not more than 1.2%, and further Zn: 0. .5-3.
0%, Sn: 0.01-0.1%, In: 0.005-
0.1%, Ga: 0.01 to 0.2%, one or more selected from the group, and Mg: 0.05 to 1.0%, C
An alloy containing u: 0.3% or less and Fe: 0.1 to 0.6%, selected from the group consisting of one or more kinds, and the balance being unavoidable impurities and Al.

(6) In the manufacturing method of the above (1), the composition of the core material contains Mn: 0.5 to 2.2%, Si: more than 0.35% and not more than 1.2%, and further Zr: 1 or 2 selected from the group of 0.25% or less and Cr: 0.25% or less
An alloy containing seeds and the balance being unavoidable impurities and Al.

(7) In the manufacturing method of the above (1), the composition of the alloy contains Mn: 0.5 to 2.2%, Si: more than 0.35% and 1.2% or less, and further Zr: 0. 1% and 2 selected from the group of 0.25% or less and Cr: 0.25% or less
And one or more selected from the group consisting of Mg: 0.05 to 1.0%, Cu: 0.3% or less, and Fe: 0.1 to 0.6%, with the balance being An alloy composed of inevitable impurities and Al.

(8) In the manufacturing method of the above (1), the alloy composition contains Mn: 0.5 to 2.2%, Si: more than 0.35% and not more than 1.2%, and further Mg: 0.05 ~
1.0%, Cu: 0.3% or less, Fe: 0.1 to 0.6
%, An alloy containing one or more selected from the group of 100% and the balance being unavoidable impurities and Al. Is the gist.

[Operation] Next, the reason why the present invention limits the component composition range and manufacturing conditions of the alloy as described above will be explained.

The reasons for limiting each component in the present invention are as follows.

Mn: Mn forms a compound of the Al-Mn-Si system to improve the strength before and after brazing. It also improves high temperature buckling resistance and moldability. If it is less than 0.5%, the effect is not sufficient, and if it exceeds 2.2%, coarse crystallized products are formed during casting, making it difficult to manufacture a plate material and reducing the thermal conductivity.

Within the above range, the higher the Mn content, the higher the strength after brazing. From this viewpoint, it is more desirable to exceed 1.5%.

Si: Si forms an Al-Mn-Si-based compound to improve the strength, and also reduces the amount of Mn dissolved in solid solution to improve the thermal conductivity. Its content is 0.35%
The effect is not sufficient below, and if it exceeds 1.2%, the fin material is melted during brazing.

Zn, In, Sn, Ga: Bases the potential of the fin material and imparts a sacrificial anode effect. If it is less than the lower limit, the effect is not sufficient, and if it exceeds the upper limit, not only the effect is saturated, but also the self-corrosion resistance and the rolling workability are deteriorated.

Zr, Cr: Both improve high temperature buckling resistance. If the upper limit is exceeded, coarse intermetallic compounds will be formed,
The fin material becomes difficult to manufacture.

Mg: Mg improves the strength of the fin.
In particular, coexistence with Si causes age hardening to improve strength without substantially lowering thermal conductivity. 0.
If it is less than 05%, the effect is not sufficient. If it exceeds 1.0%, the brazing property is impaired. That is, in the case of fluoride flux brazing, the flux reacts with Mg to cause brazing failure, and in the case of vacuum brazing, the amount of evaporated Mg increases and the brazing furnace requires more cleaning.

Cu: Cu improves the strength of the fin material. However, if the content is increased, the potential of the fin material becomes noble and the sacrificial anode effect is impaired, so it is necessary to set it to 0.3% or less.

Fe: Fe coexists with Mn to improve high temperature buckling resistance and moldability. Further, the solid solution amount of Mn is reduced to improve the thermal conductivity. If it is less than 0.1%, the effect is not sufficient, and if it exceeds 0.6%, the recrystallized grains during brazing become fine and the high temperature buckling resistance deteriorates. In particular, when the annealing temperature is lowered to increase the strength and complete recrystallization is not performed as in the present invention, the recrystallized grains tend to become fine during brazing, so Fe is 0.6%. You must avoid crossing over.

Next, the reason for limiting the manufacturing conditions will be described.

The alloy having the above composition is melted → casted →
A fin material having a temper of H1n is manufactured by the steps of homogenization treatment → hot rolling → cold rolling → intermediate annealing → final cold rolling.

It should be noted that the fin material is not limited to H1n in quality.
It may be 2n, in which case the final cold rolling is not carried out. In any of these cases, the homogenization treatment may be combined with the heating before hot rolling.

In these steps, the homogenizing treatment, hot rolling, cold rolling, annealing and final cold rolling must be carried out under the following conditions.

Homogenization Treatment Temperature If the annealing temperature is low and recrystallization is not completed as in the present invention, the recrystallized grains during brazing become fine and the high temperature buckling resistance tends to become poor. The temperature of the ingot homogenization treatment must be strictly followed. Then, in order to sufficiently precipitate fine Mn-based compounds and to obtain high strength and high temperature buckling resistance after brazing, it is necessary to carry out in a temperature range of 400 to 560 ° C. If the temperature is less than 400 ° C, Mn-based compounds (Al-Mn, Al-Mn-Fe, Al-
Precipitation of compounds such as Mn-Si and Al-Mn-Fe-Si is not sufficient, so the recrystallized grains of the fin material during brazing become fine and the high temperature buckling resistance deteriorates. Also, 560
When the temperature exceeds ° C, the Mn-based compound becomes coarse, the strength after brazing decreases, the recrystallized grains become fine during brazing, and the high temperature buckling resistance deteriorates.

[0031]Heating temperature before hot rolling The heating temperature before hot rolling should be high enough for rolling workability and high resistance.
In order to obtain warm buckling property, the range of 400-560 ℃ is preferred.
Good If this temperature is less than 400 ° C, ear cracks will be severe during rolling.
Processability deteriorates. Also, if it exceeds 560 ℃
The strength after brazing decreases and recrystallized grains during brazing
It becomes fine and the high temperature buckling resistance deteriorates. Temperature at the end of hot rolling The temperature at the end of hot rolling must be 300 ° C or lower
Is. Keep the temperature at the end of hot rolling below 300 ° C
This suppresses the precipitation of Mn-based compounds that precipitate during cooling.
Control, and a fine chemical compound that precipitates during the subsequent annealing.
The product can be sufficiently precipitated and the strength after brazing is improved.
Go up. When the temperature exceeds 300 ℃, hot rolling ends
During the subsequent cooling, the Mn-based compound was precipitated and grew greatly.
Therefore, precipitation of fine compounds becomes insufficient during annealing, and brazing
The strength afterwards becomes low.

Cold Rolling Before Annealing In cold rolling performed after hot rolling and before annealing, dislocations introduced by rolling are uniformly distributed, and in subsequent annealing, Al--Mn--Si system It aims to increase the strength after brazing by uniformly depositing fine compounds on the dislocations, and a reduction rate of 40% or more is required. If the value is less than 40%, the precipitation of fine compounds will be non-uniform and the strength after brazing will be low.

[0033] By performing to lower than usual annealing temperature annealing temperature to precipitate Al-Mn-Si-based fine compounds on top of dislocations introduced in the rolling (circle equivalent diameter 0.1μm or less), Wax It is necessary to carry out at 180 ° C. or higher and lower than 240 ° C. in order to obtain high strength after application. If the temperature is lower than 180 ° C, the precipitation of fine compounds becomes insufficient, and if it is 240 ° C or higher, the size of the precipitate becomes large, resulting in low strength after brazing.

Final Cold Rolling The present invention increases the strength of the H1n material by performing the final cold rolling at an appropriate reduction ratio, and the fin material recrystallizes at the temperature during brazing, so that the brazing material is formed. It is intended to enhance the high temperature buckling resistance by preventing the fin material from diffusing, and a rolling reduction of 5 to 50% is required.
If the value is less than 5%, the strength of the H1n material becomes low. On the other hand, if it exceeds 50%, the recrystallized grains during brazing become fine and the high temperature buckling resistance deteriorates.

The other steps, that is, melting, casting, etc., are carried out according to ordinary methods. The ingot homogenization treatment and the hot rolling heating may be performed once. Further, the annealing is not limited to once and may be performed twice or more. In that case, in the annealing just before the final cold rolling, the above temperature range may be kept.

[0036]

EXAMPLES Alloys having the compositions shown in Table 1 were melted and cast. Then, the alloys No. 1 to No. 8 were subjected to ingot homogenization treatment and hot rolling to a thickness of 2 mm, and then cold rolling,
A bare fin material having a thickness of 0.07 mm was obtained by annealing and final cold rolling.

The manufacturing conditions are shown in Table 2.

After applying a fluoride flux to the obtained fin material, the same as in brazing was performed in a nitrogen gas at 60.
After performing heat treatment at 0 ° C. for 3 minutes, a tensile test was performed. Further, in order to evaluate the sacrificial anode effect, the natural electrode potential was measured after immersing in a 3% NaCl aqueous solution adjusted to pH 3 for 1 hour.

Further, the fin material is corrugated,
3003 alloy as core material and 4045 alloy as skin material (brazing material)
It was placed on a plate material (having a thickness of 0.6 mm) and brazed with fluoride flux to examine the brazing condition.

The above results are summarized in Table 2.

[0041]

[Table 1]

[0042]

[Table 2]

[0043]

[Table 3]

Nos. 1A, 2A, 3A, 4A of the examples of the present invention,
5A, 6A, 7A, 8A, 8B, 8C, 8D, 8E, 8
The strength of F, after brazing, is as high as 130 MPa or more, the spontaneous potential is electrochemically base from −740 to −840 mV, and the brazing condition is also good.

On the other hand, Comparative Examples No. 1B, 3B, 5
B, 7B, 8G has a high ingot homogenization treatment temperature of 600 ° C, and Nos. 2B, 4B, 6B, 8H have a high heating temperature of 580 ° C before hot rolling. Was low, the recrystallized grains became fine during brazing, and fin buckling occurred during brazing. No. 1C, 2C, 3C, 4
C, 5C, 6C, 7C and 8K all have an annealing temperature of 4
Since it is as high as 00 ° C. and the precipitate grows large, the strength after brazing is low. No. 8I has a temperature of 4 at the end of hot rolling.
It is as high as 60 ° C., and since the precipitate grows large, the strength after brazing is low. No. 8J has a low reduction rate of 30% in the cold rolling before annealing, and a reduction rate of 95% in the final cold rolling.
Therefore, the strength after brazing was low, the recrystallized grains became fine during brazing, and the fins buckled during brazing. No. 8L has a low annealing temperature of 150 ° C., and the precipitation of fine compounds is small, so the strength after brazing is low.

[0046]

According to the present invention, it is possible to provide a fin material having high strength after brazing, high temperature buckling resistance and sacrificial anode function. The fins of the heat exchanger can be made thinner, which contributes to weight reduction and cost reduction of the heat exchanger.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kenji Kato 5-11-3 Shimbashi, Minato-ku, Tokyo Sumitomo Light Metal Industries, Ltd. (72) Inventor Su Kendo 5-11 Shimbashi, Minato-ku, Tokyo No. 3 Sumitomo Light Metal Industry Co., Ltd.

Claims (8)

[Claims] 1. An alloy containing Mn: 0.5 to 2.2% (weight%, the same shall apply hereinafter), Si: more than 0.35% and 1.2% or less, with the balance being inevitable impurities and Al. Of the ingot is subjected to homogenization treatment at 400 to 560 ° C., and 400 to 560
After heating to ℃ to start hot rolling, after finishing the hot rolling at 300 ℃ or less, after performing cold rolling at a reduction rate of 40% or more, after annealing at 180 ℃ or more and less than 240 ℃, A method for producing a high-strength aluminum alloy fin material for a heat exchanger, which comprises performing cold finish rolling at a rolling reduction of 5 to 50%. 2. Mn: 0.5 to 2.2%, Si: 0.3
5% to 1.2% is contained, and Zn: 0.
5 to 3.0%, Sn: 0.01 to 0.1%, In: 0.
An alloy ingot containing one kind or two or more kinds selected from the group of 005 to 0.1% and Ga: 0.01 to 0.2%, with the balance being inevitable impurities and Al, 400 to 560
After homogenizing at 400 ° C., heating to 400 to 560 ° C. to start hot rolling, and finishing hot rolling at 300 ° C. or less, 4
Cold rolled at a reduction rate of 0% or more, 180 ° C or more 24
A method for producing a high-strength aluminum alloy fin material for a heat exchanger, which comprises performing annealing at a temperature lower than 0 ° C. and then performing cold finish rolling at a reduction rate of 5 to 50%. 3. Mn: 0.5 to 2.2%, Si: 0.3
5% to 1.2% is contained, and Zn: 0.
5 to 3.0%, Sn: 0.01 to 0.1%, In: 0.
005 to 0.1%, Ga: 0.01 to 0.2%, one or more selected from the group, and Zr: 0.25% or less, Cr: 0.25% or less selected from the group 1 or 2
An ingot of an alloy containing seeds and the balance consisting of unavoidable impurities and Al was homogenized at 400 to 560 ° C.
After heating to 560 ° C. to start hot rolling, finishing hot rolling at 300 ° C. or lower, performing cold rolling at a reduction rate of 40% or higher, and annealing at 180 ° C. or higher and lower than 240 ° C. ,
Furthermore, the method for producing a high-strength aluminum alloy fin material for a heat exchanger, which comprises performing cold finish rolling at a reduction rate of 5 to 50%. 4. Mn: 0.5 to 2.2%, Si: 0.3
5% to 1.2% is contained, and Zn: 0.
5 to 3.0%, Sn: 0.01 to 0.1%, In: 0.
One or two or more selected from the group of 005 to 0.1% and Ga: 0.01 to 0.2%, and a group of Zr: 0.25% or less and Cr: 0.25% or less. 1 or 2
And one or more selected from the group consisting of Mg: 0.05 to 1.0%, Cu: 0.3% or less, and Fe: 0.1 to 0.6%, with the balance being An ingot of an alloy consisting of unavoidable impurities and Al is homogenized at 400 to 560 ° C., heated to 400 to 560 ° C. to start hot rolling, and 3
After finishing the hot rolling at 00 ° C or lower, cold rolling is performed at a rolling reduction of 40% or more, annealing is performed at 180 ° C or more and less than 240 ° C, and further cold finishing is performed at a rolling reduction of 5 to 50%. A method for producing a high-strength aluminum alloy fin material for a heat exchanger, which comprises rolling. 5. Mn: 0.5 to 2.2%, Si: 0.3
5% to 1.2% is contained, and Zn: 0.
5 to 3.0%, Sn: 0.01 to 0.1%, In: 0.
005 to 0.1%, Ga: 0.01 to 0.2%, one or more selected from the group, and Mg: 0.05 to 1.
Ingot of alloy containing 0%, Cu: 0.3% or less, Fe: 0.1 to 0.6% and one or more selected from the group, the balance being unavoidable impurities and Al. From 400
After homogenizing at 560 ° C., heating to 400 to 560 ° C. to start hot rolling, and finishing hot rolling at 300 ° C. or less, cold rolling is performed at a rolling reduction of 40% or more to 180 ° C. A method for producing a high-strength aluminum alloy fin material for a heat exchanger, which comprises annealing at 240 ° C. or higher and further cold finishing rolling at a reduction rate of 5 to 50%. 6. Mn: 0.5 to 2.2%, Si: 0.3
More than 5% and 1.2% or less, and further Zr: 0.
1 selected from the group of 25% or less and Cr: 0.25% or less
The alloy ingot containing two or two kinds and the balance consisting of unavoidable impurities and Al is homogenized at 400 to 560 ° C., heated to 400 to 560 ° C. to start hot rolling, and 3
After finishing the hot rolling at 00 ° C or less, cold rolling is performed at a reduction rate of 40% or more, annealing is performed at 180 ° C or more and less than 240 ° C, and then cold finishing is performed at a reduction rate of 5 to 50%. A method for producing a high-strength aluminum alloy fin material for a heat exchanger, which comprises rolling. 7. Mn: 0.5 to 2.2%, Si: 0.3
More than 5% and 1.2% or less, and further Zr: 0.
1 selected from the group of 25% or less and Cr: 0.25% or less
Or two, and Mg: 0.05 to 1.0%, Cu:
An alloy ingot containing one or more selected from the group of 0.3% or less and Fe: 0.1 to 0.6%, the balance being inevitable impurities and Al, 400 to 560 After homogenizing treatment at ℃, heating to 400 to 560 ℃ to start hot rolling, after finishing hot rolling at 300 ℃ or less, cold rolling is performed at a reduction rate of 40% or more, 180 ℃ or more A method for producing a high-strength aluminum alloy fin material for a heat exchanger, which comprises performing annealing at a temperature lower than 240 ° C. and then performing cold finish rolling at a reduction rate of 5 to 50%. 8. Mn: 0.5 to 2.2%, Si: 0.3
The content of Mg: 0.
05-1.0%, Cu: 0.3% or less, Fe: 0.1
An ingot of an alloy containing one or more selected from the group of 0.6% and the balance consisting of inevitable impurities and Al is homogenized at 400 to 560 ° C., and 400 to 560.
After heating to ℃ to start hot rolling, after finishing the hot rolling at 300 ℃ or less, after performing cold rolling at a reduction rate of 40% or more, after annealing at 180 ℃ or more and less than 240 ℃, A method for producing a high-strength aluminum alloy fin material for a heat exchanger, which comprises performing cold finish rolling at a rolling reduction of 5 to 50%.