JP7244383B2 - Aluminum alloy brazing sheet for heat exchanger and method for producing the same - Google Patents

Description

TECHNICAL FIELD The present invention relates to an aluminum alloy brazing sheet for heat exchangers, which is used as a heat exchanger member for automobiles and the like, and a method for producing the same.

2. Description of the Related Art In recent years, the rapid increase in the number of eco-friendly vehicles represented by electric vehicles and fuel cell vehicles has increased the demand for higher performance heat exchangers for automobiles.
Among them, the heat dissipation performance of the aluminum member for the heat exchanger contributes to the improvement of the heat dissipation performance of the heat exchanger. Here, since there is a certain correlation between the heat radiation performance and the electrical conductivity, the easily measurable electrical conductivity has been conventionally used as a criterion for judging the heat radiation performance of the material. In other words, the higher the conductivity of the material, the more the heat dissipation of the heat exchanger can be improved.

As an aluminum member for a heat exchanger, a brazing sheet has been conventionally used in which a brazing material made of an Al--Si alloy is laminated on both sides or one side of a core material made of an Al--Mn alloy. For example, in the aluminum alloy brazing sheet for heat exchangers described in Patent Document 1, one side of a core material made of an Al—Mn alloy is clad with an Al—Si brazing material, and the other side has Si: 2.5 to 6. It is clad with an aluminum alloy material containing .0% by weight. Such brazing sheets have a good balance of material strength and brazing properties, and are widely used as members for heat exchangers.

JP 2007-178062 A

However, since Mn is added to the core material of the aluminum alloy brazing sheet for heat exchangers described in Patent Document 1, it dissolves in aluminum and lowers the electrical conductivity. In addition, since the heat exchanger is joined by brazing heat treatment at about 600° C., an increase in the solid solubility of Mn due to high temperature heat treatment is unavoidable, leading to a decrease in electrical conductivity of the material.

An object of the present invention is to provide an aluminum alloy brazing sheet for heat exchangers capable of improving electrical conductivity and corrosion resistance, and a method for producing the same.

The present inventors have investigated the use of an Al--Fe alloy as an alloy for suppressing a decrease in electrical conductivity. In this Al—Fe alloy, Fe added to aluminum has a low solid solubility limit, and even in the heat of brazing addition, it hardly dissolves in aluminum, so that it is possible to prevent a decrease in electrical conductivity. However, Al—Fe alloys tend to form coarse intermetallic compounds during casting, and these intermetallic compounds tend to become recrystallization nuclei during brazing addition heat, which tends to make the crystal grains of the core material finer. I found out. When the recrystallized grains of the core material are fine in the brazing heat, the crystal grain boundary serves as an erosion path for the molten brazing filler metal, thereby promoting the erosion of the core material and lowering the brazability. Therefore, as a result of intensive research by the present inventors, by placing pure aluminum between an Al-Fe-based core material and an Al-Si-based brazing material, coarse recrystallized grains are obtained during brazing heat treatment. It was found that pure aluminum suppresses corrosion of the core material.
That is, the aluminum alloy brazing sheet for heat exchangers of the present invention is an aluminum alloy brazing sheet for heat exchangers comprising an Al--Fe-based core material and an Al--Si-based brazing material laminated on one or both sides thereof, The tensile strength after heat treatment equivalent to brazing is 100 MPa or more, and the electrical conductivity is 55% IACS or more, and the Al—Fe-based core material contains Fe: 0.3% by mass or more and 1.5% by mass or less, Cu: An aluminum alloy containing 0.1% by mass or more and 0.7% by mass or less, Si: 0.1% by mass or more and 0.3% by mass or less, and the balance being Al and inevitable impurities, and the Al—Fe An intermediate layer made of pure aluminum is formed between the core material and the Al—Si brazing filler metal, the thickness of the intermediate layer is 20 μm or more, and the average grain size of the intermediate layer is 500 μm. That's it.

The purity of the pure aluminum is at least 99.0% by mass or more. When the core material is clad with such an intermediate layer made of pure aluminum, rolling treatment such as hot rolling is performed. In this case, the intermediate layer is made of pure aluminum, has a low recrystallization temperature, and has few precipitates, so that the crystal grains become coarse. Larger grains reduce braze erosion paths and improve corrosion resistance. Therefore, if the average grain size of the intermediate layer is less than 500 μm, the effect of improving the corrosion resistance is impaired. Further, if the thickness of the intermediate layer is less than 20 μm, it may not be possible to suppress corrosion of the brazing material to the Al—Fe-based core material.
In the present invention, pure aluminum having a thickness of 20 μm or more is arranged between the Al—Fe core material and the Al—Si brazing material, so that the pure aluminum having coarse recrystallized grains during brazing addition heat is Al A high brazability can be maintained because brazing corrosion to the -Fe-based core material is suppressed. In addition, since the Al--Fe-based core material and the pure aluminum disposed between the Al--Si-based brazing material and the Al--Fe-based core material have high electrical conductivity, the aluminum alloy brazing sheet for heat exchangers Brazeability can be secured while maintaining high strength. As a result, the tensile strength after heat treatment equivalent to brazing can be 100 MPa or more, and the electrical conductivity can be 55% IACS or more.

Fe contributes to improving the strength of the core material. If it is less than 0.3% by mass, the amount of addition is small and the desired effect cannot be obtained, and if it exceeds 1.5% by mass, the castability and rollability of the core material are reduced. do.
Cu contributes to improving the strength of the core material. If it is less than 0.1% by mass, the amount of Cu added is too small to obtain the desired effect. The melting point is lowered and the brazability (conductivity) is also lowered.
Si contributes to the strength improvement of the core material. adhesion (conductivity) is reduced.
If the tensile strength after the heat treatment equivalent to brazing is less than 100 MPa, the reliability of the aluminum alloy brazing sheet for heat exchangers is lowered. The heat treatment equivalent to brazing is a heat treatment held at 600°C for 3 minutes. After holding for 3 minutes at , it is cooled to 300° C. at a cooling rate of 100° C./min, and cooled to room temperature by air cooling.

In a preferred embodiment of the aluminum alloy brazing sheet for a heat exchanger of the present invention, the Al—Si brazing material contains Si: 5.0% by mass or more and 12.0% by mass or less, and the balance is Al and inevitable impurities. It is preferable that it is made of an aluminum alloy having a composition of
Si contributes to improving the brazeability of the brazing filler metal and suppressing erosion. may decrease and the occurrence of erosion may not be suppressed.

In a preferred embodiment of the aluminum alloy brazing sheet for heat exchangers of the present invention, the Al—Si brazing material further contains Zn: 0.1% by mass or more and 3.0% by mass or less.
Zn contributes to improving the brazeability of the brazing filler metal. If it is less than 0.1% by mass, the amount of addition is too small to obtain the desired effect. , the corrosion resistance of the joint may decrease.

The method for producing an aluminum alloy brazing sheet for a heat exchanger of the present invention comprises: Fe: 0.3% by mass or more and 1.5% by mass or less, Cu: 0.1% by mass or more and 0.7% by mass or less, Si: 0.1 A core material manufacturing step of manufacturing an Al-Fe-based core material from an aluminum alloy containing not less than 0.3% by mass and the balance being Al and inevitable impurities, and the Al- An intermediate layer made of pure aluminum and having a thickness of 20 μm or more is laminated on both or one side of the Fe-based core material, and an Al--Si-based brazing material is laminated on the surface of the intermediate layer opposite to the Al--Fe-based core material. and a cladding step of cladding.

ADVANTAGE OF THE INVENTION According to this invention, the electrical conductivity and corrosion resistance of the aluminum alloy brazing sheet for heat exchangers can be improved.

BRIEF DESCRIPTION OF THE DRAWINGS It is sectional drawing of the aluminum alloy brazing for heat exchangers which concerns on one Embodiment of this invention.

Hereinafter, an aluminum alloy brazing sheet for heat exchangers and a method for producing the same according to the present invention will be described with reference to the drawings.
INDUSTRIAL APPLICABILITY An aluminum alloy brazing sheet 1 for heat exchangers according to the present invention (hereinafter simply referred to as brazing sheet 1) is used for heat exchangers for automobiles and the like.
This brazing sheet 1, as shown in FIG. ) and an intermediate layer 13 made of pure aluminum formed between the core material 11 and the brazing material 12 .

[Composition of core material]
The core material 11 contains Fe: 0.3% by mass or more and 1.5% by mass or less, Cu: 0.1% by mass or more and 0.7% by mass or less, and Si: 0.1% by mass or more and 0.3% by mass or less. and the balance is Al and unavoidable impurities.
Here, Fe contributes to improving the strength of the core material 11. If it is less than 0.3% by mass, the amount of addition is too small to obtain the desired effect. And the rollability deteriorates. Further, Cu contributes to improving the strength of the core material 11. If it is less than 0.1% by mass, the amount of Cu added is too small to obtain the desired effect. As it decreases, the melting point decreases and the brazeability (conductivity) also decreases. Furthermore, Si contributes to improving the strength of the core material 11. If it is less than 0.1% by mass, the amount added is too small to obtain the desired effect, and if it exceeds 0.3% by mass, the melting point of the core material 11 is lowered. As a result, the brazeability (conductivity) deteriorates.

More preferably, the core material 11 contains 0.5 mass % to 1.3 mass % of Fe, 0.2 mass % to 0.6 mass % of Cu, and 0.1 mass % to 0.6 mass % of Si. .3% by mass or less, with the balance being Al and unavoidable impurities.

[Composition of Brazing Material]
The brazing material 12 is made of Al--Fi based aluminum alloy. Preferably, the brazing filler metal 12 is made of an aluminum alloy containing 5.0% by mass or more and 12.0% by mass or less of Si, with the balance being Al and unavoidable impurities.
Si contributes to improving the brazeability of the brazing filler metal and suppressing erosion. may decrease and the occurrence of erosion may not be suppressed.

Moreover, the brazing material 12 preferably further contains Zn: 0.1% by mass or more and 3.0% by mass or less.
Zn contributes to improving the brazeability of the brazing filler metal. If it is less than 0.1% by mass, the amount of addition is too small to obtain the desired effect. , the corrosion resistance of the joint may decrease.

[Composition of Intermediate Layer]
The intermediate layer 13 is made of pure aluminum. The purity of this pure aluminum should be at least 99.0% by mass, more preferably 99.5% by mass or more. When the core material 11 is clad with the intermediate layer 13 made of such pure aluminum, rolling treatment such as hot rolling is performed. In this case, the intermediate layer 13 is made of pure aluminum, has a low recrystallization temperature, and has few precipitates, so that the crystal grains become coarse. Larger grains reduce braze erosion paths and improve corrosion resistance. Therefore, the intermediate layer 13 has an average grain size of 500 μm or more and a thickness of 20 μm or more. This intermediate layer 13 has the effect of suppressing the brazing erosion of the core material 11 during the brazing heat treatment. If the thickness is less than 20 μm, there is a possibility that corrosion of the brazing material to the Al—Fe-based core material cannot be suppressed.
Since the intermediate layer 13 is made of pure aluminum and has low strength, it preferably has a minimum thickness necessary for brazing corrosion resistance, and is preferably 40 μm or less. If the thickness of this intermediate layer 13 exceeds 40 μm, the strength of the brazing sheet 1 is reduced. That is, the thickness of the intermediate layer 13 is preferably 20 μm or more and 40 μm or less.

In addition, since the intermediate layer 13 is made of pure aluminum with high electrical conductivity, and the above-described core material 11 also has high electrical conductivity, the electrical conductivity of the brazing sheet 1 after the heat treatment equivalent to brazing is 55% IACS. The brazing sheet 1 after heat treatment equivalent to brazing has a tensile strength of 100 MPa or more.
The heat treatment equivalent to brazing is a heat treatment held at 600°C for 3 minutes. After holding for 3 minutes at , it is cooled to 300° C. at a cooling rate of 100° C./min, and cooled to room temperature by air cooling.

[Method for producing brazing sheet]
Next, a method for manufacturing this brazing sheet will be described.
The method for manufacturing the brazing sheet 1 includes a core material manufacturing process for manufacturing the core material 11, a brazing material manufacturing process for manufacturing the brazing material 12, an intermediate layer forming process for forming a pure aluminum plate to be the intermediate layer 13, a cladding step of laminating the intermediate layer 13 on one side of the core material 11 manufactured by the core material manufacturing process, and laminating and cladding the brazing material 12 on the surface of the intermediate layer 13 opposite to the core material 11. .

(Core manufacturing process)
First, an aluminum alloy for core material is cast by semi-continuous casting. Then, the obtained ingot (aluminum alloy for core material) is subjected to a homogenization treatment for the purpose of removing heterogeneous structures such as segregation after slab casting. Due to the high-temperature homogenization treatment, the additive element supersaturated in solid solution in the matrix during casting precipitates as an intermetallic compound. Since the size and dispersion amount of the precipitated intermetallic compound are affected by the temperature and time of the homogenization treatment, it is necessary to select heat treatment conditions according to the type of additive element.
In the present embodiment, Cu and Si are added to an Al-Fe alloy, and the aluminum alloy for the core material is cast by melting and casting them, and the obtained ingot is subjected to a homogenization treatment at 400 ° C. or higher and 520 ° C. or lower. for 5 to 15 hours at a temperature of

Then, the ingot of the aluminum alloy for core material that has been subjected to the homogenization treatment may be subjected to only a facing treatment for removing the rolled outermost surface and subjected to the cladding process described later, or hot rolled to obtain a plate material. good too. Moreover, it is good also as a board|plate material through continuous casting-rolling, without dividing a casting process and a rolling process.
Normally, hot rolling of the core material 11 is carried out at a high temperature of around 500° C., but after the rolling is finished, the core material 11 is coiled and cooled to room temperature. In this case, the time of holding at high temperature changes depending on the finishing temperature of hot rolling, which affects the precipitation behavior of intermetallic compounds.
For this reason, in the present embodiment, hot rolling is performed so that the sheet material made of the aluminum alloy for the core material has a finishing temperature of 408° C. or more and 442° C. or less.

(Brazing material manufacturing process)
An aluminum alloy for brazing material is cast by semi-continuous casting. After slab casting, the obtained ingot (aluminum alloy for brazing filler metal) is subjected to a homogenization treatment for the purpose of removing heterogeneous structures such as segregation.
The homogenization treatment of the aluminum alloy for brazing material made of Al—Si alloy is carried out at 400 to 550° C. for 1 to 15 hours. Generally, in the brazing sheet manufacturing process, the aluminum alloy for brazing material is not subjected to homogenization treatment. A large number of Si particles exist. In order to control the Si particle size in this brazing material, a homogenization treatment is effective and can be selected from the range of 400 to 550° C. for 1 to 15 hours, and 480 to 550° C. for 3 to 10 hours. It is more preferable to carry out in the range of
Then, the ingot of the aluminum alloy for brazing material that has been subjected to the homogenization treatment is hot-rolled into a plate material. In addition, it is good also as a board|plate material through continuous casting-rolling, without dividing a casting process and a rolling process.

(Intermediate layer manufacturing process)
Cast pure aluminum for the intermediate layer by semi-continuous casting. Since this pure aluminum for the intermediate layer is composed of pure aluminum, no homogenization treatment is performed.
Then, the ingot of pure aluminum for the intermediate layer, which has been subjected to the homogenization treatment, is hot-rolled into a plate material. In addition, it is good also as a board|plate material through continuous casting-rolling, without dividing a casting process and a rolling process.

(Clad process)
Then, these plate materials are clad with an appropriate clad rate. The cladding is generally done by hot rolling. Thereafter, cold rolling is applied to obtain an aluminum alloy material for heat exchangers having a desired thickness. Then, final annealing is performed at, for example, 360° C. for 3 hours to obtain a brazing sheet. Specifically, the pure aluminum for the intermediate layer is placed on the aluminum alloy for the core material, and the aluminum alloy for the brazing material is placed on the opposite side of the pure aluminum for the intermediate layer from the aluminum alloy for the core material. By performing rolling and cold rolling, the core material 11, the intermediate layer 13 and the brazing material 12 are bonded together to produce the aluminum alloy brazing sheet 1 for heat exchangers shown in FIG.

The thickness of the brazing sheet 1 is, for example, 0.4 mm in total thickness, 20 μm to 60 μm thickness of the brazing material 12 (e.g., equivalent to 5% to 15% cladding ratio), and the thickness of the intermediate layer 13 The thickness is 20 μm to 40 μm (corresponding to a cladding rate of 5% to 10%, for example), and the remaining thickness is the thickness of the core material 11 .

Hot rolling, cold rolling, and final annealing may be performed by conventional methods, but it is also possible to interpose intermediate annealing during the cold rolling process. In that case, the intermediate annealing can be performed by heating at 200 to 400° C. for 1 to 6 hours, for example. In the final rolling after intermediate annealing, rolling is performed at a cold rolling reduction of 10 to 50%.

Such a brazing sheet 1 is used, for example, as each member of a heat exchanger. The material 12 is melted and the contact portions of the members are brazed to form a heat exchanger. In this brazing heat treatment, for example, the temperature is raised from room temperature (eg, 25° C.) to 550° C. at an average temperature increase rate of 100° C./min, and the temperature increase time from 550° C. to 600° C. is 1 to 3 minutes. After holding at 600° C. for 1 to 3 minutes, cooling from 600° C. to 300° C. at a cooling rate of 68° C./min or more and 100° C./min or less, and cooling to room temperature by air cooling.

In the present embodiment, an intermediate layer 13 made of pure aluminum having a thickness of 20 μm or more is arranged between the Al—Fe-based core material 11 and the Al—Si-based brazing material 12 to prevent coarse regeneration during brazing addition heating. Since pure aluminum having crystal grains suppresses brazing corrosion of the Al—Fe-based core material 11, high brazeability can be maintained. In addition, the Al--Fe core material 11 and the intermediate layer 13 made of pure aluminum disposed between the Al--Si brazing material 12 and the Al--Fe core material 11 have high electrical conductivity. , while maintaining the high strength of the aluminum alloy brazing sheet 1 for heat exchangers, the brazeability can be ensured. As a result, the brazing sheet 1 after the heat treatment equivalent to brazing can have a tensile strength of 100 MPa or more and an electrical conductivity of 55% IACS or more.
Since the heat exchanger is composed of the heat exchanger aluminum alloy brazing sheet 1 manufactured by the above-described manufacturing method, the corrosion resistance and strength of the heat exchanger itself are increased, so the durability of the heat exchanger is improved. can be enhanced.

It should be noted that the present invention is not limited to the configurations of the above-described embodiments, and various modifications can be made to the detailed configurations without departing from the gist of the present invention.
In the above embodiment, an example in which the brazing material 12 is formed on one surface of the core material 11 via the intermediate layer 13 as the brazing sheet is shown. The brazing filler metal 12 may be formed through the intermediate layer 13 .

An aluminum alloy for the core material, an aluminum alloy for the brazing material and pure aluminum for the intermediate layer were cast by semi-continuous casting. The alloys shown in Table 1 (balance of Al and unavoidable impurities) were used as the aluminum alloy for the core material and the aluminum alloy for the brazing material, and the purity of the pure aluminum for the intermediate layer was as shown in Table 1. The core material was homogenized at 450-580° C. for 4-8 hours. Further, the material for the brazing material was subjected to homogenization treatment at 430 to 480° C. for 3 hours.
Next, a brazing filler metal is arranged on one side of the core material, and an intermediate layer is combined therebetween, hot rolled, further cold rolled to a thickness of 0.40 mm, and finally annealed at 360° C. for 3 hours. A brazing sheet (test material) with O temper was produced.
The thickness of each test material (brazing sheet) is such that the thickness of the brazing material is 40 μm (equivalent to a cladding rate of 10%), the thickness of the intermediate layer is 12 to 40 μm, and the remaining thickness is the thickness of the core material. bottom.
Then, as a heat treatment equivalent to brazing, each test material is heated at a temperature rising rate such that the time to reach the target temperature from 550 ° C. is 3 minutes, held at the target temperature of 600 ° C. for 3 minutes, and then After cooling to 300° C. at about 100° C./min, air cooling was performed to room temperature.

(Average grain size of intermediate layer)
The average crystal grain size of the intermediate layer in each test material was measured by using each test material before heat treatment equivalent to brazing, filling the cross section parallel to the rolling direction with resin, polishing it to a mirror surface, and applying an etchant (e.g., Keller at room temperature). The crystal grains of the core material were revealed by immersion in the solution for 1 to 3 minutes, and 5 locations on each test material were photographed at 200 times using an optical microscope. The grain size was measured by a cutting method in the rolling direction from the photographs taken, and the average grain size was calculated.

(Evaluation of conductivity after heat treatment equivalent to brazing)
The conductivity of each test material after the heat treatment equivalent to brazing was measured with a double-bridge conductivity meter according to the conductivity measurement method described in JIS H-0505. Those whose conductivity is 55.5% IACS or more are evaluated as good "A", those whose conductivity is 55.0% IACS or more and less than 55.5% IACS are evaluated as good "B", and less than 55.0% IAC was evaluated as unsatisfactory "C".

(Evaluation of tensile strength after heat treatment equivalent to brazing)
After the heat treatment equivalent to brazing, a sample was cut out parallel to the rolling direction to prepare a JIS No. 5 test piece, and a tensile test was performed to measure the tensile strength. The tensile speed was 3 mm/min.
Those with a tensile strength of 100 MPa or more were evaluated as good "A" in tensile strength after brazing, and those with less than 100 MPa were evaluated as unsatisfactory "C".

(Evaluation of Brazing Flow Coefficient)
The wax flow coefficient (Kd) was measured by a drop-type flow test and calculated by the following formula.
Kd = (4WB-W0)/(3W0 x cladding ratio)
W0: Weight of brazing sheet before brazing
WB: Weight of lower 1/4 of brazing sheet after brazing
Cladding rate: Cladding rate of brazing filler metal In the drop-type flow test, each test material was processed into a test piece of 60 mm long x 25 mm wide, and the mass W0 of the entire test piece in this initial state was measured. Next, in a high-purity nitrogen gas atmosphere, each vertically arranged test material is held at a temperature of 600 ° C. for 3 minutes to melt the brazing alloy, and the part from one end side of the test piece to 1/4 in the vertical direction ( That is, the mass WB of the portion of 60 mm/4=15 mm) was measured, and the flow coefficient was obtained by the above formula.
When the braze flow coefficient was 0.3 or more and less than 0.9, it was judged as good "A", and in other cases it was judged as good "B".

(Evaluation of erosion depth)
In addition to the evaluation of the brazing fluidity coefficient, the erosion depth in the plate thickness direction from the brazing filler metal/intermediate layer interface was measured by observing the cross section of the central part of the test piece. When the erosion depth was less than 20 μm, it was evaluated as good “A”, and when it was 20 μm or more, it was evaluated as unsatisfactory “C”.

(Evaluation of corrosion resistance)
A 30 × 50 mm sample was cut from each test material after heat treatment equivalent to brazing, and the brazing material layer side was placed in an aqueous solution containing Cl ⁻ : 195 ppm, SO ₄ ²⁻ : 60 ppm, Cu ²⁺ : 1 ppm, and Fe ³⁺ : 30 ppm. The immersion test was performed for 4 weeks with cycles between 80°C x 8 hours and room temperature x 16 hours. After the corrosion test, the sample was immersed in a boiling chromic acid mixed solution to remove corrosion products, and then the corrosion weight loss was measured, and the corrosion resistance was evaluated using this result. A corrosion weight loss of less than 5 mg/cm ² was evaluated as good "A", a weight loss of 5 mg/cm ² or more and less than 7 mg/cm ² was evaluated as fair "B", and 7 mg/cm ² or more. was evaluated as unsatisfactory "C".
The measurement results and evaluation described above are as shown in Tables 1 and 2.

As shown in Tables 1 and 2, in Examples 1 to 10, the core material is Fe: 0.3% by mass or more and 1.5% by mass or less, Cu: 0.1% by mass or more and 0.7% by mass or less, Si: made of an aluminum alloy having a composition containing 0.1% by mass or more and 0.3% by mass or less, the balance being Al and inevitable impurities, the thickness of the intermediate layer being 20 μm or more, and the average thickness of the intermediate layer Since the crystal grain size was 500 μm or more, the tensile strength, electrical conductivity, erosion depth, braze flow coefficient, and corrosion resistance after the heat treatment equivalent to brazing were all evaluated as acceptable “B” or higher.

On the other hand, in Comparative Examples 1 to 6, the core material is Fe: 0.3% by mass or more and 1.5% by mass or less, Cu: 0.1% by mass or more and 0.7% by mass or less, Si: 0.1% by mass or more. Since the content was not within the range of 0.3% by mass or less, any evaluation of tensile strength, electrical conductivity, and corrosion resistance after heat treatment equivalent to brazing was failed "C". In Comparative Example 7, since the thickness of the intermediate layer was as thin as 12 μm, the erosion depth was as large as 35 μm, and the evaluation was "C". Furthermore, in Comparative Example 8, since the purity of the pure aluminum constituting the intermediate layer was as low as 98%, the average crystal grain size was 480 μm, the erosion depth was as large as 25 μm, and the evaluation was not possible “C”. .

1 Aluminum alloy brazing sheet for heat exchanger (brazing sheet)
11 core material (Al-Fe-based core material)
12 Brazing material (Al-Si brazing material)
13 middle layer

Claims (4)

An aluminum alloy brazing sheet for a heat exchanger, comprising an Al--Fe-based core material and an Al--Si-based brazing material laminated on one or both sides thereof,
Tensile strength after heat treatment equivalent to brazing is 100 MPa or more, and electrical conductivity is 55% IACS or more,
The Al—Fe-based core material has Fe: 0.3% by mass or more and 1.5% by mass or less, Cu: 0.1% by mass or more and 0.7% by mass or less, Si: 0.1% by mass or more and 0.3% by mass. Made of an aluminum alloy with a composition containing 10% by mass or less, with the balance being Al and inevitable impurities,
An intermediate layer made of pure aluminum is formed between the Al—Fe-based core material and the Al—Si-based brazing filler metal, the thickness of the intermediate layer being 20 μm or more, and the average crystallinity of the intermediate layer. An aluminum alloy brazing sheet for a heat exchanger, characterized by having a particle size of 500 μm or more. 2. The method according to claim 1, wherein the Al—Si brazing material is made of an aluminum alloy having a composition containing 5.0% by mass or more and 12.0% by mass or less of Si, with the balance being Al and unavoidable impurities. The aluminum alloy brazing sheet for heat exchangers described above. 3. The aluminum alloy brazing sheet for a heat exchanger according to claim 2, wherein the Al--Si brazing material further contains Zn: 0.1% by mass or more and 3.0% by mass or less. Fe: 0.3% by mass or more and 1.5% by mass or less, Cu: 0.1% by mass or more and 0.7% by mass or less, Si: 0.1% by mass or more and 0.3% by mass or less, and the balance is A core material manufacturing process for manufacturing an Al—Fe-based core material from an aluminum alloy composed of Al and inevitable impurities;
An intermediate layer made of pure aluminum and having a thickness of 20 μm or more is laminated on both or one side of the Al—Fe-based core material manufactured by the core material manufacturing process, and the intermediate layer is placed on the opposite side of the Al—Fe-based core material. A method for producing an aluminum alloy brazing sheet for a heat exchanger, comprising: a cladding step of laminating and cladding an Al—Si brazing material on the surface of the aluminum alloy brazing sheet.

Images