JP5844411B2 - Aluminum clad material for heat exchanger - Google Patents

Description

  The present invention relates to a heat exchanger manufactured by brazing, such as brazing using a fluoride-based flux or vacuum brazing, particularly when manufacturing an aluminum alloy heat exchanger such as a radiator or an inverter cooler. In addition, it is related with the aluminum clad material for heat exchangers used suitably as the tube material and plate material which are the structural members.

  The aluminum alloy heat exchanger tube material is an aluminum alloy clad material having a two-layer structure in which an Al-Mn alloy alloy is used as a core material, and an Al-Si alloy brazing material is clad on one side of the core material. An aluminum alloy clad material having a three-layer structure in which a material is clad and a sacrificial anode material of an Al—Zn alloy or an Al—Zn—Mg alloy is clad on the other surface is used.

  In aluminum alloy heat exchangers, the core material of the clad material keeps the shape as a structural member, has a stress relaxation effect against vibration, pressure fluctuation, and thermal stress applied to the heat exchanger, and exhibits fatigue durability To do. In addition, the Al—Si brazing material is clad to braze and join the members together when an aluminum alloy heat exchanger is manufactured. Further, the sacrificial anode material is used, for example, on the inner surface or the outer surface of the tube, and exerts a sacrificial anode action in contact with the working fluid or the outside air, thereby preventing the pitting corrosion of the core material.

Japanese Patent Laid-Open No. 11-293371

  Especially in aluminum alloy heat exchangers for automobiles, it is important to have fatigue characteristics that can withstand fatigue due to stresses such as vibrations applied to the heat exchanger, and tube materials and plate materials also have excellent fatigue durability. What is needed is desired. In order to obtain a tube material with excellent fatigue characteristics and excellent corrosion resistance, the inventors reviewed the composition and combination of the core material and brazing material constituting the clad material, and the relationship with the fatigue properties of the clad material. As a result of conducting tests and studies on the above, as a core material, pure aluminum in which the amount of component elements added was suppressed was used, the generation of intermetallic compounds produced by the component elements was suppressed, and the solid solubility of Cu, Mn, and Mg was reduced. It has been found that this is effective for improving the fatigue life, particularly for improving the low cycle fatigue life.

  The present invention was made as a result of repeated testing and examination based on the above knowledge, and the object thereof is excellent in fatigue characteristics and excellent corrosion resistance, and is a tube material for an aluminum alloy heat exchanger. An object of the present invention is to provide an aluminum clad material for a heat exchanger that can be suitably used as a material for a plate material.

An aluminum clad material for a heat exchanger according to claim 1 for achieving the above object is an aluminum two-layer clad material obtained by clad a brazing material 1 having a sacrificial anode effect on the core material on one side of the core material. The core material contains Ti: 0.1000% or more and less than 0.3% , the aluminum purity is 99.0% or more and less than 99.9%, and the total content of inevitable impurities is less than 0.7%. In addition, the content of Cu, Mn, and Mg among the inevitable impurities is 0.05% or less of aluminum. Hereinafter, all alloy component values are indicated by mass%.

The aluminum clad material for a heat exchanger according to claim 2 is the aluminum clad material for heat exchanger according to claim 1 , wherein the brazing material 1 contains Si: 2.5 to 14% , or Si: 2.5 to 14%, Mg: 0.00. 1 to 2.0% , Zn: 0.5 to 10%, In: 0.001 to 0.1%, Sn: 0.001 to 0.1 % of one or two It is characterized by being composed of an Al—Si based alloy or an Al—Si—Mg based alloy containing the above and the balance Al and inevitable impurities.

The aluminum clad material for a heat exchanger according to claim 3 is the aluminum clad material for heat exchanger according to claim 2 , wherein the brazing material 1 is further Mn: 0.1 to 2.0%, Fe: 0.1 to 2.0%, Ni: 0. 0.1-2.0%, Cr: 0.01-0.3%, Zr: 0.01-0.3%, Ti: 0.01-0.35%, Sr: 0.001-0.1 %, Na: 0.001 to 0.1%, Sb: 0.001 to 0.1%, or one or more thereof.

The aluminum clad material for a heat exchanger according to claim 4 is provided with Si: 2.5 to 14% on the core material surface opposite to the brazing material 1 of the aluminum clad material for heat exchanger according to any one of claims 1 to 3. Al-Si-based alloy containing the balance Al and inevitable impurities or Si: 2.5 to 14%, Mg: 0.1 to 2.0%, the balance Al and Al- consisting of inevitable impurities A brazing material 2 made of a Si—Mg alloy is clad to form a three-layer clad material.

The aluminum clad material for a heat exchanger according to claim 5 is the aluminum clad material for heat exchanger according to claim 4 , wherein the brazing material 2 is further Fe : 0.1-2.0%, Mn: 0.1-2.0%, Ti: 0.00. 01-0.3%, Zn: 0.5-5.0%, Cu: 0.1-5.0%, Sr: 0.001-0.1%, Na: 0.001-0.1% , Sb: 0.001 to 0.1%, Bi: 0.001 to 0.2%, Be: 0.001 to 0.1%, or one or more of them are contained. .

The aluminum clad material for a heat exchanger according to claim 6 is the sum of the intermetallic compounds having a particle diameter of 1 μm or more in terms of a circle equivalent diameter among the intermetallic compounds in the matrix of the core material according to any one of claims 1 to 5. The number is 3 × 10 ⁴ or less per 1 mm ² .

  According to the present invention, an aluminum clad material having excellent fatigue characteristics, particularly low cycle fatigue characteristics, and excellent corrosion resistance, particularly suitable as a material for a tube material or a plate material that is a constituent member of an aluminum alloy heat exchanger. An aluminum alloy clad material for a heat exchanger that can be used is provided.

It is a figure which shows the outline of the bending fatigue testing machine of an aluminum clad material.

The significance and reasons for limitation of the alloy components in the aluminum clad material for heat exchangers according to the present invention will be described.
(Heartwood)
By using pure aluminum having a total content of inevitable impurities of less than 1.0% and an aluminum purity of 99.0% or more and less than 99.9% as the core material, the fatigue life, in particular, the low cycle fatigue life is improved. Can be achieved effectively. If the aluminum purity is less than 99.0%, the above effects are not sufficient, and the fatigue life, particularly the low cycle fatigue life, is reduced.

  In other words, the core material made of pure aluminum described above is less generated from the intermetallic compound due to the low concentration of the component elements compared to the Al-Mn 3003 alloy, which is a general core material alloy, from the periphery of the intermetallic compound. Since the progress of the generated fatigue cracks is delayed, excellent fatigue characteristics, particularly excellent low cycle fatigue characteristics can be obtained. When there are many intermetallic compounds, strain accumulates around the intermetallic compounds and leads to cracks. Furthermore, by suppressing the content of Cu, Mn, and Mg as impurities, the solid solution amount of Cu, Mn, and Mg decreases, so that the ductility of the matrix increases and strain around the intermetallic compound can be further relaxed. More excellent fatigue characteristics can be obtained.

In order to obtain excellent low cycle fatigue properties, among the intermetallic compounds in the matrix, the total number of intermetallic compounds having a particle diameter of 1 μm or more in terms of a circle equivalent diameter is 3 × 10 ⁴ or less per 1 mm ^2. It is preferable. More preferably 3 × 10 ³ or less, further preferably 3 × 10 ² or less, and most preferably 3 × 10 or less.

Further , the remaining components excluding aluminum are unavoidable impurities, and various elements are unavoidably present depending on the refining method, but such unavoidable impurities are in total as described above. The amount is preferably adjusted to be less than 1.0%.

In the case of pure aluminum having an aluminum purity of 99.0% or more and less than 99.9% , the above inevitable impurities are usually Fe, Si, Mn, Zn, V, Zr, Ga, etc. at a ratio of about 500 ppm or less. Contained .

Ti functions to refine the crystal grain size of the core material and further improve the low cycle fatigue life. The preferable content range of Ti is 0.1000% or more and less than 0.3%.

(Brazing material 1)
In the brazing material 1 having a sacrificial anode effect, Zn, In, and Sn, which make the potential lower, are added to an Al—Si based alloy or an Al—Si—Mg based alloy that is usually used as a brazing material. By sacrificing the potential of the brazing material, the sacrificial anode effect on the core material is maintained, and as a result, pitting corrosion of the core material is prevented. The content of Si in the brazing material is in the range of 2.5 to 14%, and the content of Mg is in the range of 0.1 to 2.0%. The preferable content range of Zn is 0.5 to 10.0%, the more preferable content range is 1 to 5%, the preferable content range of In is 0.001 to 0.1%, and the more preferable content range is 0.01 to 0%. 0.05%, the preferable content range of Sn is 0.001 to 0.1%, and the more preferable content range is 0.01 to 0.05%.

  Mn produces | generates an Al-Mn type compound, an Al-Mn type compound becomes a starting point of corrosion, and as a result of a pitting corrosion being disperse | distributed, corrosion resistance improves. A preferable content range of Mn is 0.1 to 2.0%, and if it contains more than 2.0%, a coarse compound is generated at the time of casting, rolling workability is impaired, and it is difficult to obtain a sound plate material. . The more preferable content of Mn is in the range of 0.5 to 1.7%.

  Fe produces an Al—Fe-based compound, and the Al—Fe-based compound serves as a starting point of corrosion, and as a result of the pitting corrosion being dispersed, the corrosion resistance is improved. The preferable content range of Fe is 0.1 to 2.0%, and if it exceeds 2.0%, the corrosion resistance is lowered. The more preferable content of Fe is in the range of 0.2 to 1.0%.

  Ni produces | generates an Al-Ni type compound, an Al-Ni type compound becomes a starting point of corrosion, and as a result of a pitting corrosion being disperse | distributed, corrosion resistance improves. The preferable content range of Ni is 0.1 to 2.0%, and if it exceeds 2.0%, the corrosion resistance is lowered. A more preferable content of Ni is in the range of 0.2 to 1.0%.

  Cr and Zr produce an Al—Cr-based compound and an Al—Zr-based compound, and these compounds serve as a starting point for corrosion, and as a result of pitting corrosion being dispersed, corrosion resistance is improved. The preferable content ranges of Cr and Zr are both 0.01 to 0.3%, and even if the content exceeds 0.3%, the effect is saturated and no further improvement effect can be expected. A more preferable content of Cr and Zr is in the range of 0.05 to 0.2%.

  Ti generates an Al—Ti compound, and the Al—Ti compound becomes a starting point of corrosion, and as a result of the pitting corrosion being dispersed, the corrosion resistance is improved. The preferable content range of Ti is 0.01 to 0.35%, and if it exceeds 0.35%, casting becomes difficult, and workability deteriorates and it becomes difficult to produce a sound material. A more preferable content of Ti is in the range of 0.1 to 0.2%.

  Sr, Na, and Sb finely and uniformly disperse the Si particles in the brazing material. When coarse Si particles are present, strain accumulates around the Si particles and becomes a starting point of cracks. The inclusion of Sr, Na, and Sb makes the Si particles finer, making it difficult for cracks to form, and further improving the fatigue life. The preferable content ranges of Sr, Na, and Sb are 0.001 to 0.1%, respectively, and even if the content exceeds 0.1%, the effect is saturated. A more preferable content of Sr, Na, Sb is in the range of 0.01 to 0.05%.

  The brazing material 1 includes elements added to known sacrificial anode materials, for example, Cu: 0.5% or less, V: 0.3% or less, Co: 0.3% or less, Ce: 0.3 % Or less, Y: 0.3% or less, La: 1.0% or less, Nd: 1.0% or less, Pr: 1.0% or less may be included.

(Braze material 2)
In the aluminum clad material of the present invention, a brazing material can be clad as the brazing material 2 on the core material surface opposite to the brazing material 1 to form a three-layer structure. As the brazing material 2, an Al—Si based alloy or an Al—Si—Mg based alloy that is usually used as a brazing material is used. The preferable content range of Si is 2.5 to 14%, and the preferable content range of Mg is 0.1 to 2.0%.

  For Al-Si based alloys and Al-Si-Mg based alloys, Fe: 0.1-2.0%, Mn: 0.1-2.0%, Ti: 0.01-0, as necessary. .3%, Zn: 0.5-5.0%, Cu: 0.1-5.0%, Sr: 0.001-0.1%, Na: 0.001-0.1%, Sb: One or more of 0.001 to 0.1%, Bi: 0.001 to 0.2%, and Be: 0.001 to 0.1% may be contained. In addition, the brazing material 2 includes elements added to known brazing materials, for example, V: 0.3% or less, Co: 0.3% or less, Ce: 0.3% or less, Y: 0.3% Hereinafter, La: 1.0% or less, Nd: 1.0% or less, Pr: 1.0% or less, Cr: 0.3% or less, Zr: 0.3% or less may be included.

  The aluminum clad material according to the present invention ingots the core material alloy, the brazing material alloy 1 and the brazing material 2 alloy by DC casting. For example, in the obtained ingot, the core material alloy is homogenized. The alloy for brazing filler metal 1 and the alloy for brazing filler metal 2 are hot-rolled to a predetermined thickness, and these and the ingot of the core alloy are combined and hot-rolled to obtain a clad material. Thereafter, the clad material is cold-rolled and finally annealed to obtain an aluminum clad material (for example, grade O) having a predetermined thickness. Intermediate annealing may be performed in the middle of the process, or cold rolling may be further performed after final annealing to obtain H1n according to quality.

In the aluminum clad material of the present invention, the total number of intermetallic compounds having a particle diameter of 1 μm or more in terms of a circle equivalent diameter among the intermetallic compounds in the matrix of the core material in both the two-layer structure and the three-layer structure. As a result, it is possible to obtain more excellent low cycle fatigue characteristics by being 3 × 10 ⁴ or less per 1 mm ² , and such an intermetallic compound distribution form, as a core material, suppresses the amount of inevitable impurities. This can be achieved by using pure aluminum or aluminum containing a small amount of Ti.

  Examples of the present invention will be described below in comparison with comparative examples to demonstrate the effects. These examples show one embodiment of the present invention, and the present invention is not limited thereto.

Example 1
Ingots of core material having a composition shown in Table 1 by continuous casting, an aluminum alloy for brazing material 1 having a composition shown in Table 2, and an aluminum alloy for brazing material 2 shown in Table 3 were obtained. Among them, homogenization treatment is performed on the aluminum for the core material, and the aluminum alloy for the brazing material 1 and the aluminum alloy for the brazing material 2 are hot-rolled to a predetermined thickness. It rolled and obtained the clad material of 2 layers and 3 layers. In addition, in the aluminum for core materials shown in Table 1, inevitable impurities other than the elements shown in Table 1 are 500 ppm or less for A1 and A5, 10 ppm or less for A2 and A6, and 5 ppm or less for A3 and A7. , A4 and A8 were all 1 ppm or less.

  Subsequently, the clad material was cold-rolled and finally annealed to obtain a clad plate material (quality O) having a thickness of 0.40 mm. The clad composition was such that the brazing material 1 had a cladding ratio of 10% (thickness 0.040 mm), the brazing material 2 had a cladding ratio of 10% (thickness 0.040 mm), and the remainder was the core material. Note that the plate thickness and the clad rate are not limited to those in the examples, and are appropriately adjusted and used. For example, the plate thickness can be set to 0.10 to 2.00 mm, and the cladding rate can be set to about 2 to 30%.

The obtained aluminum clad material was used as a test material, heated at 600 ° C. (material temperature) in nitrogen gas for 3 minutes without applying a flux to the clad material, and then the fatigue life was measured by a plane bending fatigue test. . In the plane bending fatigue test, after cutting the clad material after brazing and heating, the end face is cut to produce a strip-shaped test piece having a width of 5 mm, and for the test piece, using a bending fatigue tester shown in FIG. The strain range was fixed at 0.67, and a double-bending bending fatigue test was performed. The frequency was 0.5 Hz at room temperature, and the number of cycles until breakage was measured. Fatigue life was evaluated in a low cycle range of about 10 ⁴ break times, it was considered good if the fatigue life exceeds 1 × 10 ^4. The results are shown in Table 4. In Table 4, the test material 1 does not contain Ti in the core material, and the test materials 2-4, 6-18, 29-39, 51-52 are pure aluminum having an aluminum purity of 99.9% or more as the core material. The test materials 26 to 27 use the brazing material 1 that does not contain Zn, Sn, and In, and all are shown as reference examples.

As shown in Table 4, all of the test materials 5, 19 to 25, 28 , ⁴⁰ to 50, and 53 to 54 according to the present invention had excellent fatigue characteristics in which the fatigue life exceeded 1 × 10 ⁴ .

Comparative Example 1
The aluminum for core material having the composition shown in Table 5 was formed by continuous casting, and the resulting ingot was homogenized, and the heat of the aluminum alloy for brazing material 1 and the aluminum alloy for brazing material 2 used in Example 1 was obtained. A hot rolled material was combined with the hot rolled material to obtain an aluminum clad material.

Subsequently, the clad material was cold-rolled and finally annealed to obtain a clad plate material (quality O) having a thickness of 0.40 mm. The clad composition is such that the brazing material 1 has a clad rate of 10% (thickness 0.040 mm), the brazing material 2 has a clad rate of 10% (thickness 0.040 mm), and the remainder is a core material, and the resulting aluminum clad material Was used as a test material, and the fatigue life was measured by the same method as in Example 1. The results are shown in Table 6.

  As shown in Table 6, the test material 101 has a large amount of impurities because of the low aluminum purity of the core material. Therefore, when repeated stress is applied, strain accumulates around the intermetallic compound, leading to cracks, fatigue. Life was inferior.

Claims (6)

An aluminum two-layer clad material obtained by clad a brazing material 1 having a sacrificial anode effect on the core material on one side of the core material, the core material being Ti: 0.1000% (mass%, the same applies hereinafter) or more It contains less than 0.3% , the aluminum purity is 99.0% or more and less than 99.9%, the total content of inevitable impurities is less than 0.7%, and among the inevitable impurities, Cu, Mn, Mg An aluminum clad material for a heat exchanger, wherein the aluminum clad material comprises 0.05% or less of aluminum. The brazing filler metal 1 contains Si: 2.5 to 14% , or contains Si: 2.5 to 14%, Mg: 0.1 to 2.0% , and Zn: 0.5 ~10%, in: 0.001~0.1%, Sn: contain one or two or more of 0.001 to 0.1%, Al-Si system the balance being Al and unavoidable impurities The aluminum clad material for a heat exchanger according to claim 1, wherein the aluminum clad material is made of an alloy or an Al-Si-Mg alloy . The brazing filler metal 1 further has Mn: 0.1-2.0%, Fe: 0.1-2.0%, Ni: 0.1-2.0%, Cr: 0.01-0.3. %, Zr: 0.01 to 0.3%, Ti: 0.01 to 0.35%, Sr: 0.001 to 0.1%, Na: 0.001 to 0.1%, Sb: 0.0. one or heat exchanger aluminum clad material according to claim 2, characterized by containing two or more of 001 to 0.1%. The core material surface opposite to the brazing filler metal 1 of the aluminum clad material for a heat exchanger according to any one of claims 1 to 3 , containing Si: 2.5 to 14%, the balance Al and Al consisting of inevitable impurities -Cladding a brazing material 2 comprising an Si-based alloy or an Al-Si-Mg based alloy containing Si: 2.5-14%, Mg: 0.1-2.0%, the balance being Al and inevitable impurities An aluminum clad material for a heat exchanger, characterized in that a three-layer clad material is obtained. The brazing filler metal 2 is further Fe : 0.1-2.0%, Mn: 0.1-2.0%, Ti: 0.01-0.3%, Zn: 0.5-5.0% Cu: 0.1-5.0%, Sr: 0.001-0.1%, Na: 0.001-0.1%, Sb: 0.001-0.1%, Bi: 0.001 The aluminum clad material for a heat exchanger according to claim 4 , comprising one or more of ˜0.2% and Be: 0.001 to 0.1%. 2. The intermetallic compound having a particle diameter of 1 μm or more in a circle equivalent diameter among the intermetallic compounds in the matrix of the core material is 3 × 10 ⁴ or less per 1 mm ² as a total number . The aluminum clad material for a heat exchanger according to any one of 5 .

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