JP2001288522A - High strength and high thermal conductivity aluminum alloy material and its producing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high strength and high thermal conductivity aluminum alloy material excellent in both strength and thermal conductivity. SOLUTION: This high strength and high thermal conductivity aluminum alloy material has a composition containing, by mass, 2.0 to 3.0% Fe and 0.5 to 1.5% Si, and the balance Al with inevitable impurities. Further, the alloy material may contain 0.5 to 1.0% Ni, <0.3% Cu and <0.2% Zr.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-strength, high-thermal-conductivity aluminum alloy material used as a fin material for a radiator, a heater, a condenser, an evaporator, etc., which are heat exchangers for automobiles manufactured by brazing, and to the production thereof. About the method.

[0002]

2. Description of the Related Art For example, a radiator, which is a heat exchanger for an automobile, is manufactured by alternately superposing a flat tube made of an aluminum alloy and a fin material formed by corrugation, and integrally brazing. In recent years, from the viewpoint of global environmental protection, heat exchangers have also been required to be reduced in weight, higher in performance, and smaller in size, and materials used for the heat exchangers have been reduced in thickness. Further, the fin material is required to have high strength and high thermal conductivity.

Hitherto, as high-strength aluminum alloy fin materials, Al-Mn alloy materials and Al-Mn-Si alloy materials have been proposed. However, these aluminum alloy materials have a high solid solubility of Mn, and Mn greatly reduces the electrical conductivity, so that the thermal conductivity of the aluminum alloy material is low. For this reason, it is necessary to secure conductivity by increasing the cross-sectional area, and there is a limit to thinning. Therefore, in order to improve the thermal conductivity, Al-Fe-based alloy materials and Al-Fe-Si-Ni-based alloy materials that do not contain Mn have been proposed.

[0004]

However, the above Al-
Fe-based alloy materials and Al-Fe-Si-Ni-based alloy materials have low strength, and a predetermined plate thickness is required in order to obtain required strength, and there is a problem that there is a limit to thinning. . As described above, there is a problem that it is difficult to manufacture a fin material that satisfies the performance required for strength and thermal conductivity.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a high-strength and high-thermal-conductivity aluminum alloy material having excellent strength and thermal conductivity, and a method for producing the same.

[0006]

The high-strength and high-thermal-conductivity aluminum alloy material according to the present invention contains 2.0 to 3.0% by mass of Fe and 0.5 to 1.5% by mass of Si, and the balance is rest. Are Al and inevitable impurities.

In this case, it is preferable to further contain 0.5 to 1.0% by mass of Ni.

Further, it is preferable to further contain Cu: less than 0.3% by mass. Further, it is preferable to contain Zr: less than 0.2% by mass. Further, there are second phase particles with respect to the parent phase, and the density of the second phase particles is 5 × 10 ⁶ particles / mm ²
It is preferred that

In the method for producing a high-strength high-thermal-conductivity aluminum alloy according to the present invention, the cooling rate during casting of the high-strength high-thermal-conductivity aluminum alloy according to any one of claims 1 to 4 is 1 ° C./min. It is characterized by exceeding.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention has been made to solve the above-mentioned problems, and the present inventors have made Al-Fe-
As a result of intensive experiments and studies on the composition, structure and manufacturing method of the Si-Ni-based alloy, it was found that both strength and thermal conductivity were excellent by appropriately defining the contents of Si and Fe.

Further, when manufacturing the aluminum alloy material of the present invention, it has been found that the cooling rate at the time of casting is set to 1 ° C./sec or more, whereby the particle size of the second phase particles can be reduced and the amount thereof can be increased. did.

The aluminum alloy material of the present invention can be applied to a fin material for an automobile heat exchanger. Thereby, an automobile heat exchanger having excellent strength and thermal conductivity can be obtained.

Hereinafter, the composition of the high-strength and high-thermal-conductivity aluminum alloy material of the present invention and the reasons for limiting the numerical values of the manufacturing method thereof will be described.

Si: 0.5 to 1.5% by mass Si enhances solid solution and improves strength by its addition.
If the content of Si is less than 0.5% by mass, sufficient strength cannot be obtained. On the other hand, when the content of Si exceeds 1.5% by mass, erosion by the brazing material becomes large at the time of brazing and heating, and the brazing property decreases. Also, by adding Si,
Since the conductivity is reduced, it is necessary to balance the strength with the thermal conductivity to suppress the amount of Si to be added. Therefore, Si
Is 0.5 to 1.5% by mass.

Fe: 2.0 to 3.0% by mass Fe is added, and part of it contributes to solid solution strengthening, and the other part exists as an intermetallic compound and contributes to dispersion strengthening. At this time, if Ni is contained in the parent phase, Fe forms an intermetallic compound together with Ni, and this intermetallic compound exists as a second phase particle with respect to the parent phase and contributes to dispersion strengthening. Thus, the strength can be improved by adding Fe. If the Fe content is less than 2.0% by mass, sufficient strength cannot be obtained. On the other hand, when the content of Fe exceeds 3.0% by mass, castability and workability of the material are reduced. Also, since the thermal conductivity is reduced by the addition of Fe, it is necessary to balance the strength with the thermal conductivity to suppress the Fe content. Therefore, the content of Fe is set to 2.0 to 3.0% by mass.

Ni: 0.5 to 1.0% by mass Ni, similarly to Fe, partially contributes to solid solution strengthening, and the remainder forms an intermetallic compound with Fe. It exists as a second phase particle for the phase and contributes to dispersion strengthening. Thus, the strength can be improved by adding Ni. If the Ni content is less than 0.5% by mass, sufficient strength cannot be obtained. On the other hand, if the content of Ni exceeds 1.0% by mass, the effect of improving the strength is saturated, so that adding more Ni is costly and uneconomical. In addition, since the thermal conductivity is reduced by the addition of Ni, it is necessary to balance the strength with the thermal conductivity to suppress the Ni content. Therefore, the content of Ni is preferably set to 0.5 to 1.0% by mass.

Cu: less than 0.3% by mass Cu, like Si, is solid-solution strengthened by its addition to improve the strength. On the other hand, as the added amount of Cu increases, the thermal conductivity decreases. Further, the potential becomes noble, and the sacrificial anode effect of the material is reduced. Therefore, the content of Cu is preferably less than 0.3% by mass.

Zr: less than 0.2% by mass Zr has an effect of coarsening recrystallized grains during brazing by adding Zr, suppresses erosion of the fin material by the brazing material, and improves brazing properties. . The effect of improving the brazing property is exerted even when the added amount of Zr is very small,
Is sufficient if the content is 0.05% by mass or more. On the other hand, when the content of Zr exceeds 0.2% by mass, the effect of improving the brazing property is saturated. Further, since the thermal conductivity is reduced by the addition of Zr, it is necessary to balance the brazing property and the thermal conductivity to suppress the amount of Zr added. Therefore, the content of Zr is preferably less than 0.2% by mass. More preferably, the content of Zr is 0.05 to 0.2% by mass.

Density of second phase particles: 5 × 10 ⁶ particles / mm ^{2 or} less
The upper main, of the second phase particles consisting of Al-Fe-based alloy, is that the effect of dispersion strengthening, the particle size of the second phase particles is only relatively small. In the present invention, the particle size is 5
Those having a size of μm or less contribute to dispersion enhancement. When the density of the second phase particles is less than 5 × 10 ⁶ particles / mm ² , the effect of dispersion strengthening is small. Therefore, the density of the second phase particles is 5 × 10 ⁶ particles /
mm ² or more.

Cooling rate during casting: 1 ° C./sec or more In the aluminum alloy material of the present invention, the faster the cooling rate during casting, the smaller the particle size of the second phase particles, and The density of the phase particles can be increased. If the cooling rate at the time of casting is less than 1 ° C./sec, the number of the second phase particles having a particle size of 5 μm or more which does not contribute to dispersion strengthening tends to increase. On the other hand, when the cooling rate during casting is 1 ° C./second or more, the particle size of the second phase particles is mostly 5 μm or less, and the density of the second phase particles having a particle size of 5 μm or less is 5 × 10 ⁶ particles. / Mm ² or more. Therefore, the cooling rate during casting is 1 ° C.
/ Sec or more.

The aluminum alloy material of the present invention can be used as a single material, and can also be used as a core material of a brazing sheet fin material. When used as the core material of brazing sheet fin material,
The brazing material is a conventionally used Al-Si or Al
-Si-Mg (Bi) -based brazing material can be used as it is. Furthermore, when vacuum brazing is applied as a brazing method, Mg can be added in addition to the above-described elements. The addition of Mg is effective in improving the strength. In this case, the addition amount of Mg is preferably 0.5 to 2.0% by mass. 0.5% by mass of Mg
If it is less than 3, Mg evaporates from the fin material during vacuum brazing, and the effect of improving the strength is reduced. On the other hand, if the Mg content exceeds 1.5% by mass, M
Since the amount of evaporation of g increases, the number of maintenance operations of the vacuum furnace increases and the cost increases.

Further, as an element other than Mg, an element such as Zn which makes the potential of the fin material low may be added in order to improve the sacrificial anode effect of the fin material. In this case, the amount of Zn added is preferably 3% by mass or less. When the addition amount of Zn exceeds 3% by mass, the self-corrosion of the fin material increases, and the consumption rate increases. Further, the workability of the fin material is reduced, which is not preferable.

[0023]

EXAMPLES Hereinafter, a fin material is manufactured by using an aluminum alloy material, and characteristics of an example falling within the scope of the present invention will be specifically described in comparison with comparative examples.

First Example Using a high-strength, high-thermal-conductivity aluminum alloy having the composition shown in Table 1 below, casting, homogenizing heat treatment and rolling were performed by a conventional method to produce a fin material. In addition, this fin material has a plate thickness of 0.07 mm and is tempered to H14.

Next, the fin material is placed in a nitrogen atmosphere (oxygen concentration is 100 mass ppm or less) at a temperature of 600.degree.
The brazing heating was performed by holding for a minute. Then strength,
Thermal conductivity and brazing properties were evaluated.

The strength was evaluated by taking a JIS-5 test piece from each fin material and performing a tensile test to measure the tensile strength.

The thermal conductivity was evaluated by measuring the electric resistance of each fin material by measuring the electric resistance by a four-terminal method and converting the electric resistance into the electric conductivity. In addition, the electrical conductivity is standard annealed copper (IACS: Intern).
ational Annealed Copper Standard, specific resistance is 1.
7241 μΩ · cm · 20 ° C.) assuming a conductivity of 100.

FIG. 1 is a schematic perspective view showing the core of the heat exchanger. The core is formed by joining a fin material 1 sandwiched between a pair of plates 2. The fin material 1 has a plate thickness of 0.07 mm, a fin height of 9 mm, a number of peaks of 10, a fin pitch of 3 mm, and a fin width of 20 mm. Plate material 2 is composed of 4045 alloy material, 3003 alloy material and 70
It is a laminated material of 72 alloys, with a thickness of 0.3 mm and a width of 3
0 mm and length is 40 mm. The cladding ratio of the plate material 2 is 10%.

Regarding the brazing properties, for each fin material 1, commercially available KF-Al
F-type flux was applied at 3 g / m ² and dried. Then, the fin material 1 was sandwiched between the plate materials 2 and brazed and heated in a nitrogen atmosphere (oxygen concentration of 100 mass ppm or less) at a temperature of 600 ° C. for 2 minutes to produce the core shown in FIG. Then, the state of erosion and buckling of the brazing material on the fin material 1 at the joint between the fin material 1 and the plate material 2 was observed and evaluated. The brazing property was evaluated as ◎ when there was no erosion or buckling, as ○ when there was some erosion and no buckling, and x when there was erosion and buckling. Table 2 shows the results.

[0030]

[Table 1]

[0031]

[Table 2]

As shown in Table 2, claim 1 of the present invention
In Examples Nos. 1 to 12 satisfying the above, the strength and the electrical conductivity were high, and the brazing properties were good. In Examples 9 to 12 to which Zr was added, the brazing properties were even better.

On the other hand, Comparative Example No. 42 was low in strength because the content of Si was less than the lower limit of the present invention. Comparative example
No. 43, since the content of Si exceeds the upper limit of the present invention, after brazing, the fin material is melted and buckled,
A core having a good shape could not be produced. Comparative Example No. 44 had low strength because the Fe content was less than the lower limit of the present invention. In Comparative Example No. 45, since the Fe content exceeded the upper limit of the present invention, due to poor casting,
A normal fin material could not be produced.

Second Embodiment Of the aluminum alloys shown in Table 1 above, alloy Nos. 1 and 2
For 4, 6, and 10, fin materials having different second-phase particles were produced by changing the casting speed, the amount of cooling water, and the like. Then, in the same manner as in the first example, tests for strength, conductivity, and brazing property were performed, and the results were evaluated. Table 3 shows the results. The density of the second phase particles shown in Table 3 is the density of particles having a particle diameter of 5 μm or less.

The presence state of the second phase particles was determined by measuring the particles having a particle diameter of 5 μm or less from an image taken with a scanning electron microscope using an image processing apparatus.

[0036]

[Table 3]

As shown in Table 3, Examples 13 to 16 satisfying claim 5 of the present application have higher strength,
The conductivity was high and the brazing properties were good. In addition, Example No. 16 to which Zr was added had even better brazing properties. On the other hand, a comparative example deviating from claim 4
Nos. 46 to 49 were lower in strength than the examples.

Third Embodiment Of the aluminum alloys shown in Table 1 above, Alloy No. 1
Regarding 4, 6, and 10, fin materials were produced by changing the cooling rate during casting under various conditions during production. Then, in the same manner as in the first example, tests for strength, conductivity, and brazing property were performed, and the results were evaluated. Table 4 shows the results.

[0039]

[Table 4]

As shown in Table 4 above, Examples Nos. 17 to 20 had high strength and electrical conductivity and good brazing properties. In addition, Example No. 20 to which Zr was added had even better brazing properties.

On the other hand, Comparative Examples Nos. 50 to 53 were low in strength because the cooling rate during casting was less than the lower limit of the present invention.

Fourth Example A fin material was manufactured in the same manner as in the first example using a high-strength, high-thermal-conductivity aluminum alloy having the composition shown in Table 5 below. Then, in the same manner as in the first example, tests for strength, conductivity, and brazing property were performed, and the results were evaluated. Table 6 shows the results.

[0043]

[Table 5]

[0044]

[Table 6]

As shown in Table 6 above, Examples Nos. 21 to 31 were high in strength and electrical conductivity and good in brazing properties. In Examples Nos. 26, 27, 30, and 31, since Zr was added, the brazing properties were much better.

On the other hand, Comparative Example No. 54 had low strength because the content of Si was less than the lower limit of the present invention. Comparative example
No. 55, since the content of Si exceeds the upper limit of the present invention, after brazing, the fin material is melted and buckled,
A core having a good shape could not be produced. Comparative Example No. 56 had low strength because the Fe content was less than the lower limit of the present invention. In Comparative Example No. 57, since the Fe content exceeded the upper limit of the present invention, due to poor casting,
A normal fin material could not be produced.

Fifth Embodiment Of the aluminum alloys shown in Table 5 above, alloy No. 1
With respect to 6, 19, 21, 24, and 25, fin materials in which the state of existence of the second phase particles were different were produced. Then, in the same manner as in the first example, tests for strength, conductivity, and brazing property were performed, and the results were evaluated. Table 7 shows the results. The density of the second phase particles shown in Table 7 is the density of particles having a particle diameter of 5 μm or less.

[0048]

[Table 7]

As shown in Table 7, Examples Nos. 32 to 36 satisfying claim 5 of the present application have higher strengths,
The conductivity was high and the brazing properties were good. Examples Nos. 34 and 36 to which Zr was added had even better brazing properties. On the other hand, Comparative Examples Nos. 58 to 62 deviating from Claim 4 had lower strength than the Examples.

Sixth Embodiment Of the aluminum alloys shown in Table 6 above, alloy No. 1
6, 19, 21, 24, and 25 were manufactured by changing the cooling rate during casting under various conditions when manufacturing the fin materials. Then, in the same manner as in the first example, tests for strength, conductivity, and brazing property were performed, and the results were evaluated. Table 8 shows the results.

[0051]

[Table 8]

As shown in Table 8 above, Example Nos. 37 to 4
Sample No. 1 had high strength and electrical conductivity and good brazing properties. Examples Nos. 39 and 4 to which Zr was added
In No. 1, the brazing properties were even better.

On the other hand, Comparative Examples Nos. 63 to 67 were low in strength because the cooling rate during casting was less than the lower limit of the present invention.

[0054]

As described above in detail, according to the present invention, since the composition, structure and manufacturing method of the aluminum alloy material are properly specified, the strength is high, the thermal conductivity is excellent, and the brazing property is excellent. A good aluminum alloy material can be obtained. Further, this aluminum alloy material can be applied to a fin material for an automobile heat exchanger.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view showing a core of a heat exchanger.

[Explanation of symbols]

 1: fin material 2: plate material

Claims (6)

[Claims] 1. Fe: 2.0 to 3.0 mass% and S
i: A high-strength and high-thermal-conductivity aluminum alloy material containing 0.5 to 1.5% by mass, with the balance being Al and inevitable impurities. 2. The high-strength high-thermal-conductivity aluminum alloy material according to claim 1, further comprising 0.5 to 1.0% by mass of Ni. 3. The high-strength and high-thermal-conductivity aluminum alloy material according to claim 1, further comprising Cu: less than 0.3% by mass. 4. The high-strength and high-thermal-conductivity aluminum alloy material according to claim 1, further comprising Zr: less than 0.2% by mass. 5. The method according to claim 1, wherein a second phase particle is present with respect to the mother phase, and the density of the second phase particle is 5 × 10 ⁶ particles / mm ^2. The high-strength high-thermal-conductivity aluminum alloy material described in the above. 6. A high-strength high-thermal-conductivity aluminum alloy material, wherein the high-strength high-thermal-conductivity aluminum alloy material according to any one of claims 1 to 4 has a cooling rate at the time of casting exceeding 1 ° C./min. Manufacturing method.