JP2004176091A - High strength aluminum alloy fin material for automotive heat exchanger having excellent rollability, and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an aluminum alloy fin material for automotive heat exchanger having excellent characteristics of strength and rollability. <P>SOLUTION: The fin material has a composition which consists of, by weight, >2.0 to 3.0% Mn, 0.8 to 1.5% Si, 0.05 to <0.4% Fe, 0.1 to 3.0% Zn and the balance Al with inevitable impurities and in which respective contents of Mn, Si and Fe satisfy relational inequality Mn/(Si+Fe)≥1.6. <P>COPYRIGHT: (C)2004,JPO

Description

【００２８】
【発明の効果】
以上説明したように、本発明の圧延性に優れた自動車熱交換器用高強度アルミニウム合金フィン材及びその製造方法によれば、優れた強度、圧延性を有するフィン材が得られる。[0001]
TECHNICAL FIELD OF THE INVENTION
TECHNICAL FIELD The present invention relates to an aluminum alloy fin material used for a radiator or the like, particularly for an automotive heat exchanger manufactured by a brazing method, and a method of manufacturing the same.
[0002]
[Prior art]
A fin material, which is a structural member of a heat exchanger generally used as a radiator of an automobile, is brazed to a coolant passage forming body (for example, a pipe material) with an Al-Si brazing material and is metallically bonded to reduce a heat transfer area. The heat exchange efficiency is improved by making it wider. As the fin material, a pure Al-based alloy such as an AA1050 alloy, an Al-Mn-based alloy such as an AA3003 alloy, an Al-Fe-based alloy, or the like is used.
Due to the recent reduction in the weight of automobiles, automobile heat exchangers are also required to be reduced in weight, and fin materials are also required to be thinner and have higher strength.
Conventionally, AA1050 alloy, AA3003 alloy, or the like has been used as the fin material, but for the purpose of increasing the strength, Mn: 0.6 to 2.0%, Si: 1.2 to 2.5%, and Fe: 0. High-strength Al alloy fin material defined by a composition of 0.05 to 2.0% (see Patent Document 1), Mn: 0.5 to 2.0%, Si: more than 0.4 to 2%, Ni: An Al alloy fin material defined by a composition of 0.1 to 1.0% (see Patent Document 2) has been developed.
[0003]
[Patent Document 1]
JP-A-7-90446 (page 2)
[Patent Document 2]
JP-A-2000-273565 (page 2)
[0004]
[Problems to be solved by the invention]
However, there is a limit to achieving high strength even with such a conventional fin material. Further, when high strength is to be achieved, there are problems such as remarkably poor rollability, remarkably large side cracks at the time of rolling, lowering the yield, and easily breaking during rolling. Those that have insufficient strength and self-corrosion resistance, or have high strength, but lack erosion resistance and thermal conductivity, and can satisfy all of thermal conductivity, self-corrosion resistance and erosion resistance and strength Did not. The lack of any of these properties not only makes it impossible to satisfy the properties required for the fin material of the heat exchanger, but also causes a problem that the performance of the heat exchanger cannot be avoided.
[0005]
In view of the above, the present inventors have studied to obtain a fin material having high strength and excellent rollability. It has been found that this problem is particularly caused by coarsening of the crystallized product.
The present invention provides a high-strength aluminum alloy fin material for an automotive heat exchanger excellent in rollability and a method for producing the same based on the above findings.
[0006]
[Means for Solving the Problems]
In order to solve the above problems, among the high-strength aluminum alloy fin materials for automobile heat exchangers excellent in rollability according to the present invention, the invention according to claim 1 is based on Mn: more than 2.0 to 3.0% by weight. , Si: 0.8 to 1.5%, Fe: 0.05 to less than 0.4%, Zn: 0.1 to 3.0%, and the balance is composed of Al and unavoidable impurities. The content of Si and Fe satisfies the relational expression of Mn / (Si + Fe) ≧ 1.6.
[0007]
The high-strength aluminum alloy fin material for automobile heat exchangers excellent in rollability according to claim 2 further includes Ni: 0.01 to 1.0% by weight in the invention according to claim 1, The balance has a composition consisting of Al and inevitable impurities, and the contents of Mn, Si, and Ni satisfy a relational expression of Mn- (Si + Ni) ≧ 0.
[0008]
The high-strength aluminum alloy fin material for an automobile heat exchanger having excellent rollability according to claim 3 is the invention according to claim 1 or 2, further comprising, in terms of% by weight, Zr: 0.05 to 0.20%; : One or two of 0.01 to 0.30% are contained, and the balance has a composition of Al and unavoidable impurities.
[0009]
The high-strength aluminum alloy fin material for automobile heat exchangers excellent in rollability according to claim 4 is the invention according to any one of claims 1 to 3, further comprising: 20%, Sn: One or two of 0.01% to 0.50%, and the balance is characterized by having a composition of Al and unavoidable impurities.
[0010]
A method for producing a high-strength aluminum alloy fin material for an automotive heat exchanger having excellent rollability according to claim 5 is a high-strength automotive heat exchanger having an excellent rollability having the composition according to any one of claims 1 to 4. The method for producing an aluminum alloy fin material is characterized in that a cooling rate during casting is set to 15 to 1000 ° C./s.
[0011]
Hereinafter, matters limited by the present invention will be described.
Mn: more than 2.0 to 3.0%
Mn crystallizes or precipitates as an intermetallic compound and improves the strength after brazing. Further, by forming an Al-Mn-Si-based compound, the solid solubility of Si in the matrix can be reduced, and the melting point of the matrix can be improved. If it is 2.0% or less, the above effect is small, and if it exceeds 3.0%, coarse crystals are formed, and castability and rollability are significantly reduced.
[0012]
Si: 0.8-1.5%
Si is dispersed or solid-dissolved in a matrix as Al-Mn-Si, Al-Fe-Si, Al-Mn-Si-Fe, or Zr-Si-based compound to improve the strength. Further, the formation of such a compound lowers the solid solubility of Mn or Zr after brazing and improves the thermal conductivity. If it is less than 0.8%, the above effect is small, and if it exceeds 1.5%, coarse crystals are formed and castability and rolling property are remarkably reduced. In addition, the melting point is lowered, and it melts during brazing. Furthermore, the solid solubility of Si increases and the thermal conductivity decreases.
[0013]
Fe: 0.05 to less than 0.4% Fe crystallizes or precipitates as an intermetallic compound and improves the strength after brazing. In addition, Al-Mn-Fe, Al-Fe-Si, and Al-Mn-Fe-Si-based compounds are formed to reduce the solid solubility of Mn and Si in the matrix and improve the thermal conductivity. If it is less than 0.05%, the above effect is small, and if it is 0.4% or more, coarse crystals are formed and castability and rollability are remarkably reduced.
[0014]
Zn: 0.1-3.0%
Zn makes the potential lower than that of the non-joined member, and acts as a sacrificial anode material. If it is less than 0.1%, the above effect is small, and if it exceeds 3.0%, the self-corrosion rate becomes extremely large.
[0015]
Mn / (Si + Fe) ≧ 1.6
It is preferable to satisfy the above-mentioned relational expression, since the crystallized material is refined, and the rollability is not reduced while improving the strength. If the relational expression is less than 1.6, the crystallized material becomes coarse and the rollability is reduced, and at the same time, the strength is lowered.
[0016]
Ni: 0.01 to 1.0%
Ni crystallizes or precipitates as an intermetallic compound and improves the strength after brazing. If it is less than 0.01%, the above effect is small, and if it exceeds 1.0%, the self-corrosion rate becomes extremely large. Further, since an Al-Mn-Ni-based compound is formed, excessive elemental Si is formed, which causes a decrease in the solidus temperature and facilitates melting during brazing.
[0017]
Mn− (Si + Ni) ≧ 0
It is preferable that the above-mentioned relational expression be satisfied, since simple Si that does not form a compound forms a solid solution in the fin material matrix to lower the melting point. When the relational expression is not satisfied, problems such as susceptibility to erosion by molten brazing during brazing heat treatment and melting of the fin material itself occur.
[0018]
Zr: 0.05 to 0.20%, Ti: 0.01 to 0.30%
Zr and Ti are dispersed as fine intermetallic compounds after brazing to improve the strength. When Zr: less than 0.05% and Ti: less than 0.01%, the above effect is small, and when Zr: more than 0.20% and Ti: more than 0.30%, castability and rollability are significantly reduced. I do.
[0019]
In: 0.001 to 0.20%, Sn: 0.01 to 0.50%
In and Sn make the potential lower than that of the non-joined member and act as a sacrificial anode material. If In is less than 0.001% and Sn is less than 0.01%, the above effect is small, and if In is more than 0.20% and Sn is more than 0.50%, the self-corrosion rate is significantly increased. In addition, the rollability decreases.
[0020]
Cooling rate during casting: 15-1000 ° C / s
If the cooling rate at the time of casting is 15 to 1000 ° C./s, the cooling rate is high, so that the formation of coarse crystals can be suppressed, and the rollability and strength can be further improved. Note that even if the cooling rate is higher than 1000 ° C./s, no further effect is obtained, so the cooling rate is set to 15 to 1000 ° C./s.
[0021]
BEST MODE FOR CARRYING OUT THE INVENTION
The aluminum alloy used for the fin material of the present invention can be produced by a conventional method according to the above composition. The production method of the fin material of the present invention is not limited. The fin material obtained as described above is usually subjected to corrugation to form fins. The fins are assembled by, for example, being installed between tubes, and are subjected to a brazing process to obtain a heat exchanger.
[0022]
【Example】
An aluminum alloy having the composition shown in Table 1 was cast at a different cooling rate during casting, and subjected to hot rolling and / or cold rolling, intermediate annealing, and cold rolling to obtain a rolled material having a thickness of 0.06 mm. Produced.
[0023]
Tensile strength after brazing To evaluate the strength of the fin material after brazing, heat treatment equivalent to brazing a fin material alone in a high-purity nitrogen gas atmosphere (600 to 610 ° C × 5 minutes, cooling rate 100 ° C / min) And a tensile test was performed to measure the tensile strength. Since the tensile strength of the conventional fin material manufactured using the AA3003 alloy was 110 MPa, those having a tensile strength of 145 MPa or more were judged to be sufficiently strong.
[0024]
Rollability The rollability of the fin material was evaluated by a value obtained by dividing the total length of the side cracks after rolling by the length of the material after rolling. After rolling to a plate thickness of 2 mm, the end face was cut under the same conditions to obtain a sample having a length of 200 mm and a width of 100 mm. Thereafter, intermediate annealing was performed at 560 ° C. for 60 s (conditions for completely softening any material). Then, cold rolling was performed to 0.1 mm, and the rolling property was evaluated. In addition, it was determined that side cracks of less than 0.5 mm did not substantially pose a problem, and side cracks of 0.5 mm or more were targeted. When it was 0.15 or less, it was determined that the rolling property was sufficient.
[0025]
In order to evaluate fining material buckling due to brazing erosion and fin material melting during brazing heat treatment, the fin material melting starts when the temperature is raised at a rate of 10 ° C./min. The temperature was investigated. Since the brazing heat treatment was carried out at a temperature of about 600 ° C., those having a fin material melting start temperature of 610 ° C. or higher were judged to have sufficient brazing erosion resistance.
[0026]
The results of each evaluation are shown in Table 1, and all the materials of the present invention showed excellent strength and rollability.
[0027]
[Table 1]

[0028]
【The invention's effect】
As described above, according to the high-strength aluminum alloy fin material for an automotive heat exchanger of the present invention having excellent rollability and the method for producing the same, a fin material having excellent strength and rollability can be obtained.

Claims (5)

By weight%, Mn: more than 2.0 to 3.0%, Si: 0.8 to 1.5%, Fe: 0.05 to less than 0.4%, Zn: 0.1 to 3.0%, An automobile having excellent rollability, characterized in that the balance has a composition of Al and unavoidable impurities, and the contents of Mn, Si and Fe satisfy a relational expression of Mn / (Si + Fe) ≧ 1.6. High strength aluminum alloy fin material for exchangers. Furthermore, Ni: 0.01 to 1.0% by weight% is contained, and the contents of Mn, Si and Ni satisfy the relational expression of Mn- (Si + Ni) ≧ 0. 2. A high-strength aluminum alloy fin material for automobile heat exchangers having excellent rollability according to 1. 3. The composition according to claim 1, further comprising one or two of 0.05 to 0.20% of Zr and 0.01 to 0.30% of Ti in weight%. High strength aluminum alloy fin material for automotive heat exchanger with excellent rollability. 4. The method according to claim 1, further comprising one or more of In: 0.001 to 0.20% and Sn: 0.01 to 0.50% by weight%. A high-strength aluminum alloy fin material for automobile heat exchangers excellent in rollability as described in (1). 5. A method for producing a high-strength aluminum alloy fin material for an automotive heat exchanger having an excellent rollability having the composition according to claim 1, wherein the cooling rate during casting is 15 to 1000 ° C./s. A method for producing a high-strength aluminum alloy fin material for an automobile heat exchanger having excellent rollability characterized by the following.