JP4916334B2 - Aluminum alloy clad material for heat exchangers with excellent strength and brazing - Google Patents

Description

  In the case of manufacturing an aluminum heat exchanger such as a radiator or a heater core by brazing using a fluoride flux or a flux containing a cesium compound in an inert gas atmosphere, this invention is a tube material (cladding material) that is a structural member of the heat exchanger. Aluminum for heat exchangers with excellent strength and brazing properties suitable for piping materials for connecting these heat exchangers, including header plates (including bent, welded or brazed tube shapes) It relates to an alloy cladding material.

  For tube materials and header plate materials such as radiators and heater cores of automobiles, an Al-Mn alloy such as JIS A3003 is used as a core material, and a brazing material of an Al-Si alloy is clad on one side, and in some cases the other A three-layer clad material having a thickness of about 0.3 mm is used in which a sacrificial anode material made of an Al—Zn alloy or an Al—Zn—Mg alloy is clad on the surface.

  The brazing material of Al-Si alloy is for joining tubes and fins, joining tubes and header plates, and brazing is performed using an inert gas atmosphere using a fluoride flux or a flux containing a cesium compound. It is performed by brazing or vacuum brazing. In addition, the sacrificial anode material on the inner surface of the tube material comes into contact with the working fluid during use and exhibits a sacrificial anode effect to prevent pitting corrosion and crevice corrosion of the core material. The sacrificial anode material on the outer surface of the tube material is sacrificed during use. Demonstrate pitting corrosion of core material by demonstrating anode effect.

  For piping materials connecting between heat exchangers of automobiles, an Al-Mn alloy such as JIS A3003 is used as a core material, and a sacrificial anode material of Al-Zn alloy such as JIS A7072 is clad on the inner surface or the inner and outer surfaces. Two-layer or three-layer clad tubes are used. The sacrificial anode material on the inner surface of the clad tube is in contact with the coolant during use to exert a sacrificial anode effect to prevent the occurrence of pitting corrosion or crevice corrosion on the core material, and the outer surface sacrificial anode material is used in harsh environments. When used, the sacrificial anode effect is exhibited to prevent pitting corrosion or crevice corrosion occurring in the core material.

  As shown in FIG. 1, the radiator and the heater core are manufactured by bending and welding the brazing material 3 with the brazing material 3 on one side of the core material 2 and the sacrificial anode material 4 on the other side (welding portion W). It was made by flattening the tube, assembling it to the header plate, and then brazing it integrally (welding type), but recently, as shown in FIGS. Thus, a method of manufacturing a tube by forming it into a tube shape and assembling it to a header plate and integrally brazing (brazing die) is performed.

  In recent years, with the demand for lighter automobiles, automobile heat exchangers are also required to be made thinner from the viewpoint of energy saving and resource saving, and the tube materials are also becoming thinner. In order to reduce the thickness of the tube material, the core material contains a large amount of Mn, Cu, Si, etc. because it is necessary to increase the strength of the material. However, since the corrosion resistance of the core material is reduced by the inclusion of these elements, the sacrificial anode material A material structure has been proposed in which a large amount of Zn is added to ensure a potential difference from the core material and the sacrificial anode effect is reliably obtained.

Further, a large amount of Mg is added to the sacrificial anode material, and Mg ₂ Si is finely precipitated at the interface between the sacrificial anode material and the core material, or a small amount of 0.05 to 0.5% Mg is added to the core material. A material structure in which Mg ₂ Si is finely precipitated and the strength is further increased has been proposed (see Patent Document 1). When adding Mg to the sacrificial anode material, it is effective for the welding mold, but for the brazing mold, there is a surface where the sacrificial anode material and the braze are directly joined, and Mg reacts with the flux to produce MgF ₂ or the like. There is a problem that a compound is formed and the function of the flux is impaired, and a brazing defect occurs. When Mg is added to the core material, Mg diffuses from the core material to the brazing material. Similarly, Mg reacts with the flux to form a compound such as MgF ₂ , thereby reducing the function of the flux and causing a brazing defect. For this reason, the amount of Mg added is limited to 0.5% or less, and in the case of a brazing type, there is a limit to increasing the strength by adding Mg.

Therefore, for increasing the strength of the brazing die, a method has been proposed in which a large amount of Mn, Cu, Si, etc. is added to the core material, and Mn, Fe, Si is also added to the sacrificial anode material (Patent Document 2). However, it is necessary to further improve to meet the required thinning, and the addition of these elements reduces the wettability of the sacrificial anode material surface and solves the problem of brazing defects. There must be.
Japanese Patent Laid-Open No. 11-61305 JP 2003-293064 A

  In order to achieve higher brazing strength and higher brazing performance for the brazing-type radiator tube, and to obtain improved brazing performance, the inventors have determined the strength and brazing performance of the cladding material and the core material in the cladding material. As a result of testing and investigating the relationship between the composition of the sacrificial anode material and its combination, and the relationship between the structure of the core material and the sacrificial anode material, Mg diffusion occurs mainly through the crystal grain boundaries of the core material, brazing heating It has been found that if the recrystallized grains inside are coarsened, diffusion from the core material to the brazing material is suppressed, and even when a large amount of Mg is added, sound brazing is possible.

  In addition, when a large amount of Mn, Cu, Si is added to the core material to obtain high strength, a large number of Al-Mn-based and Al-Si-based compounds are formed, which are recrystallization nuclei during brazing heating. Therefore, when the ratio of Mn amount to Si amount (Mn% / Si%) is within a specific range, recrystallization is more effective than Al-Mn and Al-Si compounds. It was found that an Al—Mn—Si compound that is difficult to become a core of the metal is easily formed, the proportion of the Al—Mn—Si compound is increased, and the recrystallized grains during brazing heating can be coarsened.

  As for the sacrificial anode material, it is effective to contain elements such as Mn, Fe, Si, etc. in order to increase the strength of the tube material. The wettability decreases and the brazing property is impaired. As a result of examining the wettability of the sacrificial anode surface, it was found that Si in the brazing material mainly diffused through crystal grain boundaries on the surface of the sacrificial anode material, and in order to solve this problem, The refinement of crystal grain on the surface of the sacrificial anode material during brazing heating is effective. The refinement of crystal grain on the surface of the sacrificial anode material involves the ratio of Mn amount to Si amount (Mn% / Si%) and Fe, Ni Was found to be effective. FIG. 4 shows an example of the relationship between the ratio of Mn amount to Si amount (Mn% / Si%) in the core material and sacrificial anode material and the crystal grain size after brazing heating.

  The present invention has been made on the basis of the above knowledge, and the object thereof is to provide high strength and excellent brazing, and heat exchangers, in particular, tube materials, header plate materials, and piping materials for automotive heat exchangers. An object of the present invention is to provide an aluminum alloy clad material for a heat exchanger that can be suitably used as a material for the heat exchanger.

  The aluminum alloy clad material for heat exchanger excellent in strength and brazing according to claim 1 for achieving the above object is an aluminum alloy clad material obtained by clad a sacrificial anode material on at least one surface of a core material. The core material is Si: 0.3-1.2%, Fe: 0.01-1.0%, Cu: 0.6% or less, Mn: 0.6-1.8%, Mg: 0.5 And a ratio of Mn content to Si content (Mn% / Si%) is 2.0 or less, and is composed of an aluminum alloy composed of the remaining Al and impurities, and a sacrificial anode The material is Si: 0.1 to 1.0%, Fe: 0.05 to 0.5%, Mn: 0.6 to 2.0%, Zn: 1.0 to 5.0%, Ni: 0 .01 to 1.0%, and the ratio of Mn content to Si content (Mn% / Si%) is 2.0 or more. Characterized in that it is made of aluminum alloy and the balance Al and impurities.

  An aluminum alloy clad material for a heat exchanger excellent in strength and brazing according to claim 2 is the aluminum alloy clad material for heat exchanger according to claim 1, wherein a sacrificial anode material is clad on one surface of the core material, and an Al-Si brazing material on the other surface. Is clad.

  The aluminum alloy clad material for a heat exchanger excellent in strength and brazing property according to claim 3 is the aluminum alloy clad material for heat exchanger according to claim 2, wherein the Al-Si brazing material is Si: 7-13%, Fe: 0.15-2. Containing 0%, Zn: 0.5-5.0%, Cu: 0.5-5.0%, Sr: 0.005-0.1%, In: 0.05% or less, Sn: It contains one or more of 0.05 or less, and is composed of the balance Al and unavoidable impurities.

  The aluminum alloy clad material for a heat exchanger excellent in strength and brazeability according to claim 4 is characterized in that, in claim 1, sacrificial anode materials are clad on both surfaces of the core material.

  The aluminum alloy clad material for a heat exchanger excellent in strength and brazing according to claim 5 is the heat-treatable aluminum alloy clad material according to any one of claims 1 to 4, wherein the core material is further Cr: 0.02-0.3%, Zr: 0.00. It contains 1 type or 2 types in 02-0.3%, It is characterized by the above-mentioned.

  The aluminum alloy clad material for a heat exchanger excellent in strength and brazing property according to claim 6 is any one of claims 1 to 5, wherein the core material further contains Ti: 0.05 to 0.35%. It is characterized by.

  The aluminum alloy clad material for a heat exchanger excellent in strength and brazing property according to claim 7 is any one of claims 1 to 6, wherein the core material is further V: 0.01 to 0.3%, B: 0. It is characterized by containing 1 type or 2 types among 0.01-0.3%.

  The aluminum alloy clad material for a heat exchanger excellent in strength and brazing property according to claim 8 is the sacrificial anode material according to any one of claims 1 to 7, further containing Ti: 0.01 to 0.35% It is characterized by doing.

  The aluminum alloy clad material for a heat exchanger excellent in strength and brazeability according to claim 9 is any one of claims 1 to 8, wherein the sacrificial anode material is further In: 0.05% or less, Sn: 0.00. It contains one or two of 05 or less.

  The aluminum alloy clad material for heat exchanger excellent in strength and brazing property according to claim 10 is characterized in that in any one of claims 1 to 9, the core material has an average grain size after brazing heating of 200 µm or more. And

  The aluminum alloy clad material for heat exchangers excellent in strength and brazing property according to claim 11 has an average crystal grain size after brazing heating of the sacrificial anode material in any one of claims 1 to 10 μm or less. It is characterized by.

  According to the present invention, aluminum for heat exchangers that has high strength and excellent brazing properties, and can be suitably used as a material for heat exchangers, particularly tube materials, header plate materials, and piping materials for automotive heat exchangers. An alloy cladding material is provided.

The significance of the alloy components in the aluminum alloy clad material for heat exchangers according to the present invention and the reasons for their limitation will be described.
(Heartwood)
Mn: Mn functions to improve the corrosion resistance by improving the strength of the core material and making the potential of the core material noble and increasing the potential difference from the sacrificial anode material. A preferable content range is 0.6% to 1.8%, and if the content is less than 0.6%, the effect is small. If the content exceeds 1.8%, a coarse compound is generated at the time of casting, and the rollability is low. As a result of harm, it is difficult to obtain a healthy plate. A more preferable content range of Mn is 1.0 to 1.3%.

Mg: Mg improves the strength of the core material by solid solution hardening and fine precipitation hardening of the compound Mg ₂ Si with Si. Preferred content range is 1.0% or less than 0.5%, no sufficient effect of improving the strength is 0.5% or less, when the content exceeds 1.0% Mg and a compound of flux MgF _2, etc. Is produced in large quantities and brazing properties are reduced.

Si: Si has a function of improving the strength of the core material by solid solution hardening and fine precipitation hardening of Mg ₂ Si, a compound of Mg. A preferable content range is 0.3 to 1.2%. If the content exceeds 1.2%, the corrosion resistance is lowered, the melting point of the core material is lowered, and local melting is likely to occur during brazing. The more preferable content range of Si is 0.5 to 1.0%.

  Fe: Fe has a function of improving the strength of the core material. A preferable range is 0.01 to 1.0%, and the effect is small when the content is 0.01% or less. When the content exceeds 1.0%, the self-corrosion property of the core material increases. A more preferable content range of Fe is 0.1 to 0.7%.

  Cu: Cu functions to improve the anticorrosion effect by improving the strength of the core material, making the potential of the core material noble, and increasing the potential difference from the sacrificial anode material. Furthermore, Cu in the core material diffuses into the sacrificial anode material during brazing heating and forms a gentle concentration gradient. As a result, the potential on the core material side becomes noble and the potential on the surface side of the sacrificial anode material becomes base and sacrificed. A gentle potential distribution is formed in the anode material, and the corrosion form is changed to the full corrosion type. The preferable content of Cu is limited to 0.6% or less. This is because when Mg exceeding 0.5% is added as in the core material of the present invention, if Cu exceeds 0.6%, the melting point of the core material is lowered and local melting is likely to occur during brazing. Because. A more preferable content range of Cu is 0.1 to 0.4%.

  Mn% / Si%: The ratio of Mn content to Si content (Mn% / Si%) affects the crystal grain size of the core material as described above. In order to coarsen the crystal grains of the core material and suppress the diffusion of Mg of the core material into the brazing material, it is preferable that Mn% / Si% is 2.0 or less. A more preferable range of Mn% / Si% is 1.7 or less.

  Cr and Zr: Cr and Zr increase the recrystallization temperature during brazing heating and coarsen the grain size of the core material to suppress Mg grain boundary diffusion during brazing heating. A preferable content range is 0.02 to 0.3%, and even if the content exceeds 0.3%, the effect is saturated. A more preferable content range of Cr and Zr is 0.05 to 0.2%.

  Ti: Ti is divided into a high-concentration region and a low region in the thickness direction of the core material, and the layers are alternately distributed. Corrosion occurs by preferentially corroding the low-Ti concentration region over the high-concentration region. It has the effect of layering the form, thereby preventing the progress of corrosion in the thickness direction and improving the pitting corrosion resistance of the material. If the content is less than 0.05%, this effect is small, and if it exceeds 0.35%, casting becomes difficult, and workability deteriorates, making it difficult to produce a sound material. A more preferable content range of Ti is 0.1 to 0.2%.

  V and B: V and B coarsen the grain size of the core material and suppress Mg grain boundary diffusion during brazing heating. A preferable content range is 0.01 to 0.3%, and even if the content exceeds 0.3%, the effect is saturated.

(Sacrificial anode material)
Mn: Mn improves the strength of the sacrificial anode material. In addition, the Al—Mn compound serves as a starting point of corrosion, and the pitting corrosion is dispersed to improve the corrosion resistance. A preferable content range is 0.6% to 2.0%, and if the content is less than 0.6%, the effect is small. If the content exceeds 2.0%, a coarse compound is generated at the time of casting, and the rollability is low. It is difficult to obtain a healthy plate material. A more preferable content range of Mn is 1.3 to 1.7%.

  Zn: Zn lowers the potential of the sacrificial anode material and maintains the sacrificial anode effect on the core material. As a result, pitting corrosion and crevice corrosion of the core material are prevented. The preferable range of Zn is 1.0 to 5.0%. When the content is less than 1.0%, the effect is small, and when the content exceeds 5.0%, the self-corrosion property of the sacrificial anode material increases. The more preferable content range of Zn is 2.0 to 4.0%.

  Si: Si improves the strength of the sacrificial anode material. In addition, Al—Mn—Si, Al—Fe—Si, and Al—Mn—Fe—Si compounds are formed, which serve as starting points for corrosion, and the corrosion resistance is improved by dispersing pitting corrosion. . A preferable content range is 0.1 to 1.0%, and if it exceeds 1.0%, the corrosion resistance is lowered. A more preferable content range of Si is 0.3 to 0.7%.

  Fe: Fe improves the strength of the sacrificial anode material. In addition, Al-Fe-based, Al-Fe-Si-based, Al-Mn-Fe-based and Al-Mn-Fe-Si-based compounds are generated, and these serve as a starting point for corrosion and pitting corrosion is dispersed. Corrosion resistance is improved. A preferable range is 0.05 to 0.5%, and if it is 0.05% or less, the effect is small, and if it exceeds 0.5%, the corrosion resistance is lowered. In addition, Fe is effective for refining the crystal grains of the sacrificial anode material because the Al—Fe-based compound serves as a nucleus for recrystallization. It is more preferable to contain 2 to 0.5%.

  Ni produces an Al—Ni-based compound, which serves as a nucleus for recrystallization, and is therefore effective for refining the crystal grains of the sacrificial anode material. In order to refine the sacrificial anode material, the preferable Ni content is in the range of 0.01 to 1.0%. If the content is less than 0.01%, the effect is not sufficient. The self-corrosion property of the anode material is increased. A more preferable content range of Ni is 0.1 to 0.5%.

  Mn% / Si%: The ratio of Mn content to Si content (Mn% / Si%) affects the crystal grain size of the sacrificial anode material as described above. In order to reduce the crystal grains of the sacrificial anode material and improve the wettability of the brazing anode material surface, it is preferable to set Mn% / Si% to 2.0 or more. A more preferable range of Mn% / Si% is 2.5 or more.

  Ti: Ti is divided into a high-concentration region and a low region in the thickness direction of the sacrificial anode material, and the layers are alternately distributed, and the low-Ti concentration region corrodes preferentially compared to the high region. It has the effect of layering the corrosion form, thereby preventing the progress of corrosion in the plate thickness direction and improving the pitting corrosion resistance of the material. If the content is less than 0.01%, this effect is small, and if it exceeds 0.35%, casting becomes difficult, and workability deteriorates, making it difficult to produce a sound material. A more preferable content range of Ti is 0.1 to 0.2%.

  In, Sn: In and Sn lower the potential of the sacrificial anode material by adding a small amount, ensure the sacrificial anode effect on the core material, and prevent pitting corrosion and crevice corrosion of the core material. The preferable range of In and Sn is 0.05% or less, and if it exceeds 0.05%, the self-corrosion property of the sacrificial anode material increases. A more preferable content range of In and Sn is 0.01 to 0.03%.

(Brazing material)
Si: An Al—Si based alloy is used as the brazing material, and an alloy containing 7 to 13% Si is usually used. If the content is less than 7%, the fluidity tends to decrease and does not act effectively, and if it exceeds 13%, it is difficult to produce a sound material. In order to ensure brazing of the material containing Mg in the core material, the Si content range is preferably 9.5 to 12.0%. If the Si content is less than 9.5%, the amount of brazing material may be insufficient. If the Si content exceeds 12.0%, coarse crystallized products of Si are generated in the brazing material, resulting in non-uniform melting of the brazing. A flaw is likely to occur.

  Fe: Fe forms an Al-Fe-based or Al-Fe-Si-based compound, and these compounds serve as a starting point for corrosion to disperse pitting corrosion. As a result, the corrosion resistance of the outer surface is improved. The preferable content range of Fe is 0.15 to 2.0%. If the content is less than 0.15%, the effect is small, and if the content exceeds 2.0%, the corrosion resistance of the outer surface is lowered. A more preferable content range of Fe is 0.5 to 1.0%.

  Zn: Zn lowers the potential of the brazing material and maintains the sacrificial anode effect on the core material. As a result, pitting corrosion and crevice corrosion of the core material from the outer surface are prevented. Moreover, by making it coexist with Cu, melting | fusing point of a brazing material is reduced. The preferable content range of Zn is 0.5 to 5.0%. If the content is less than 0.5%, the effect is small, and if it exceeds 5.0%, the self-corrosion property of the brazing material increases. The more preferable content range of Zn is 0.9 to 1.5%.

  Cu: Cu coexists with Zn, thereby lowering the melting point of the brazing material. The preferable content range of Cu is 0.5 to 5.0%. If the content is less than 0.5%, the effect is small. If the content exceeds 5.0%, the self-corrosion property of the brazing material increases. A more preferable content range of Cu is 1 to 3%.

  Sr: Sr has an effect of making the existence form of the Si particles finer and uniform, and as a result, the melting of the brazing becomes uniform and the brazing property is improved. Moreover, since the presence form of the Si particles after brazing becomes fine and uniform, the corrosion resistance of the outer surface is also improved. The preferable content range of Sr is 0.005 to 0.1%. If the content is less than 0.005%, the effect is small, and even if the content exceeds 0.1%, the effect is saturated. A more preferable content range of Sr is 0.01 to 0.03%. In addition, even if Na: 1 to 100 ppm and Sb: 0.001 to 0.5% are added, the same effect can be obtained.

  In, Sn: In and Sn add a small amount to lower the potential of the brazing material and maintain the sacrificial anode effect on the core material. As a result, pitting corrosion and crevice corrosion of the core material are prevented. A preferable content range of In and Sn is 0.05% or less, and when each content exceeds 0.05%, the self-corrosion property of the brazing material increases. A more preferable content range of In and Sn is 0.01 to 0.03%.

  In the present invention, even if the core material contains a large amount of Mg, in order to prevent Mg from diffusing from the core material to the brazing material and impairing the brazing property, Mn% / Si% is more preferably 2.0 or less. Is 1.7 or less, and it is necessary to coarsen the recrystallized grains of the core material during brazing heating. In this case, the average crystal grain size of the core material is preferably 200 μm or more.

  In addition, Mn% / Si% is set to 2.0 or more in order to suppress a decrease in wettability of the sacrificial anode material surface when Mn, Fe, Si, or the like is added to the sacrificial anode material for high strength. More preferably, the grain size of the sacrificial anode material is refined to 2.5 or more, and an Al-Fe-based compound is formed by adding a specific amount of Fe and Ni, which is used as a nucleus for recrystallization during brazing heating. It is necessary to refine the recrystallized grains of the sacrificial anode material and promote the surface diffusion of Si. In this case, the average crystal grain size of the sacrificial anode material is preferably 200 μm or less. A more preferable range of the average crystal grain size of the sacrificial anode material is less than 100 μm.

  The aluminum alloy clad material according to the present invention ingots a core material alloy, a sacrificial anode material alloy and a brazing material alloy by continuous casting. For example, among the obtained ingots, the core material alloy and the sacrificial anode material alloy Is subjected to a homogenization treatment, and hot rolled the sacrificial anode material alloy and brazing material alloy to a predetermined thickness, and these are combined with the ingot of the core material alloy and hot rolled to obtain a clad material. .

  Thereafter, the clad material is cold-rolled, intermediate-annealed, and cold-rolled to obtain an aluminum alloy clad material (for example, H14) having a predetermined thickness. In this case, in the intermediate annealing, the maximum temperature is preferably 360 ° C. or less and the holding time at the maximum temperature is preferably 5 hours or less in order to suppress diffusion of Mg of the core material into the brazing material. The degree of cold rolling is preferably 40% or less in order to coarsen the average grain size of the core material after brazing heating to 200 μm or more, and the average grain size of the sacrificial anode material after brazing heating is 200 μm or less. In order to make it finer, it is desirable to make it 20% or more. The degree of cold rolling for obtaining the contradictory characteristics of the coarse grain of the core material and the fine grain of the sacrificial anode material is adjusted in accordance with the shape of the heat exchanger.

  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 An alloy for a core material having a composition shown in Table 1, an alloy for a sacrificial anode material having a composition shown in Table 2, and an alloy for a brazing material having a composition shown in Table 3 were obtained by ingot casting. Among the ingots, the alloy for the core material and the alloy for the sacrificial anode material are homogenized, and the alloy for the sacrificial anode material and the alloy for the brazing material are hot-rolled to a predetermined thickness. Were combined and hot rolled to obtain a clad material.

  Subsequently, the clad material was cold-rolled, intermediate-annealed, and cold-rolled to obtain an aluminum alloy clad material (H14) having a thickness of 0.20 mm. The structure of the clad was 0.020 to 0.050 mm for the sacrificial anode material, 0.020 to 0.050 mm for the brazing material, and the remainder was the core material. The intermediate annealing temperature was 350 ° C. and the holding time was 3 hours. The degree of cold rolling work after intermediate annealing was 30%.

  Using the obtained aluminum alloy clad material as a test material, the average crystal grain size of the core material after brazing and heating, and the average crystal grain size of the sacrificial anode material were measured by the following method. Wet spreadability, strength characteristics (tensile strength), and sacrificial anode material surface corrosion resistance (internal corrosion resistance) were evaluated. The reason for measuring the average crystal grain size after brazing heating is that the grain size of recrystallized grains generated during brazing heating hardly changes even when brazing heating is completed. The results are shown in Tables 4-6.

  Measurement of average grain size of core material: Fluoride flux was applied only to the brazing material surface of the clad material, and heated in nitrogen gas at 595 ° C. (material temperature) for 3 minutes. The temperature was raised at about 30 ° C./min. For the test material after heating, the brazing material surface was polished with emery paper (500 to 2400) by 50 μm to expose the core material (L-LT direction), and finished to a mirror surface by buffing. Furthermore, electrolysis was performed at a voltage of 25 to 30 V for 45 to 60 seconds in a mixed solution of 500 ml of pure water, 27 ml (46%) of hydrofluoric acid, and 11 g of boric acid. Thereafter, the polarization microstructure on the core material surface was photographed using an optical microscope, and the crystal grain size was measured by a comparative method. For comparison, the standard grain size structure chart of ASTM (E112-61) was used, and the grain size shown in the standard grain size structure chart was used as an index of the average grain size.

  Measurement of average grain size of sacrificial anode material: Fluoride flux was applied only to the brazing material surface of the clad plate material, and heated in nitrogen gas at 595 ° C. (material temperature) for 3 minutes. The temperature is raised under heating conditions of about 30 ° C./minute. The sacrificial anode material surface (L-LT direction) is polished several μm with emery paper (1000 to 2400) for the heated test material, and then mirror-finished by buffing. Finished. Furthermore, electrolysis was performed at a voltage of 25 to 30 V for 45 to 60 seconds in a mixed solution of 500 ml of pure water, 27 ml (46%) of hydrofluoric acid, and 11 g of boric acid. Thereafter, the polarization microstructure on the surface of the sacrificial anode material was photographed using an optical microscope, and the crystal grain size was measured by a comparative method. For comparison, the standard grain size structure chart of ASTM (E112-61) was used, and the grain size shown in the standard grain size structure chart was used as an index of the average grain size.

Evaluation of brazing property: After applying 15 g / m ² of a fluoride-based flux only to the brazing material surface of the obtained aluminum alloy clad material, as shown in FIG. combined to produce a gap-filling test piece, in nitrogen gas, it was heated for three minutes at 595 ° C. (material temperature), measured filling length of the brazing material after heating indicated by F _L in FIG. 6 (junction length) The bonding length of 10 mm or more was evaluated as good (◯), and the length of less than 10 mm was evaluated as defective (×).

  Evaluation of brazing wettability on the surface of the sacrificial anode material: Using the obtained aluminum alloy clad material, a 20 mm x 60 mm test piece was cut out, and end faces (all four faces) were cut by shaper processing to obtain 15 mm x 55 mm Finished in size. This plate was placed horizontally in the furnace with the sacrificial anode material face up without applying flux, and heated in nitrogen gas at 595 ° C. (material temperature) for 3 minutes. A photograph of the sacrificial anode material surface after heating taken at a magnification of 16 using an optical microscope (negative-positive reversal photography) (FIG. 7). The average value L of the wax circumference from the top (for example, L = (L1 + L2 in FIG. 7) ) / 2) was measured. In the evaluation of the wetting and spreading property of the wax, the average value L of the wax circumference length was evaluated as good (◯) when the average value L was 1.3 mm or more, and as poor (×) when less than 1.3 mm.

Evaluation of strength characteristics (tensile strength): After applying 15 g / m ² of fluoride-based flux only to the brazing filler metal surface of the obtained aluminum alloy clad material, heating in nitrogen gas at 595 ° C. (material temperature) for 3 minutes Thereafter, a tensile test (based on JIS Z2241) was performed.

Evaluation of the corrosion resistance (internal corrosion resistance) of the sacrificial anode material: The obtained aluminum alloy clad material was heated in nitrogen gas at 595 ° C. (material temperature) for 3 minutes without applying a flux, and then tested for 50 mm × 80 mm. Cut the piece, seal the brazing filler metal surface and the end face with silicon resin, perform the corrosion test by the following method on the sacrificial anode material surface using the following corrosive liquid, and the corrosion depth is less than 0.07 mm ( ○), 0.07 mm or more was evaluated as defective (x).
Corrosion solution: Cl ⁻ : 300 ppm, SO ₄ ²⁻ : 100 ppm, Cu ²⁺ : 10 ppm
Specific liquid volume: 5 to 10 mL / cm ²
Method: After heating at 88 ° C. for 8 hours, a cycle of cooling and holding at 25 ° C. × 16 hours was repeatedly tested for 4 months. The corrosive liquid was replaced once a month.

  As seen in Tables 4-6, the test material No. All of Nos. 1 to 65 were excellent in brazeability and wettability and spreadability of the sacrificial anode material surface, had sufficient strength, and had good inner surface corrosion resistance.

Comparative Example 1
The ingot for core material having the composition shown in Table 7 and the alloy for sacrificial anode material having the composition shown in Table 8 are formed by continuous casting, and then homogenized, and the sacrificial anode material alloy is hot-rolled to a predetermined value. The sacrificial anode alloy as a sacrificial anode alloy and the sacrificial anode alloy B2 hot rolled to a predetermined thickness after ingot formation in Example 1, and hot rolled to a predetermined thickness after ingot formation in Example 1 The brazing material alloy C1, the core material alloy and the ingots of the core material alloys A1 and A7 formed in Example 1 were combined and hot-rolled to obtain a clad material.

  Subsequently, the clad material was cold-rolled, intermediate-annealed, and cold-rolled to obtain an aluminum alloy clad material (H14) having a thickness of 0.20 mm. The structure of the clad was 0.020 to 0.050 mm for the sacrificial anode material, 0.020 to 0.050 mm for the brazing material, and the remainder was the core material. The intermediate annealing temperature was 350 ° C. and the holding time was 3 hours. The degree of cold rolling work after intermediate annealing was 30%.

  Using the obtained aluminum alloy clad material as a test material, the average crystal grain size of the core material and the average crystal grain size of the sacrificial anode material were measured by the same method as in Example 1, and the brazing performance and the wetting spread of the brazing on the sacrificial anode material surface , Strength characteristics (tensile strength), and corrosion resistance (internal corrosion resistance) of the sacrificial anode material surface were evaluated. The results are shown in Table 9.

  As shown in Table 9, the test material No. Nos. 101 to 103 have a large Mn% / Si% of the core material, and the recrystallized grains of the core material during brazing heating cannot be coarsened, and the average crystal grain size of the core material after brazing heating becomes less than 200 μm. The brazing property is inferior due to the diffusion to the wax. Test material No. Nos. 104 to 105 have small Mn% / Si% of the sacrificial anode material, and the test material No. No. 106, the sacrificial anode material does not contain Ni, the crystal grain refinement of the sacrificial anode material surface during brazing heating cannot be obtained, and the average crystal grain size of the sacrificial anode material after brazing heating exceeds 200 μm Thus, the sacrificial anode material is inferior in the wetting and spreading properties of the wax. Test material No. No. 107 has a small amount of Mg in the core material. No. 108 has a low tensile strength because the sacrificial anode material has a small amount of Si, Fe, and Mn.

It is sectional drawing which shows the tube shape of a welding type. It is sectional drawing which shows the Example of a brazing-type tube shape. It is sectional drawing which shows the other Example of the brazing-type tube shape. It is a figure which shows an example of the relationship between the ratio (Mn% / Si%) of Mn amount and Si amount in a core material and a sacrificial anode material, and a crystal grain size. It is a figure which shows the gap filling test piece used by brazing property evaluation. It is a diagram illustrating the filling length F _L of the brazing material after the test of the gap filling specimens of FIG. It is a figure which shows the circumference | surroundings length in the solder | pewter wettability evaluation of the sacrificial anode material surface.

Explanation of symbols

1 Clad plate material 2 Core material 3 Brazing material 4 Sacrificial anode material

Claims (11)

An aluminum alloy clad material obtained by cladding a sacrificial anode material on at least one surface of a core material, wherein the core material is Si: 0.3 to 1.2% (mass%, the same applies hereinafter), Fe: 0.01 to 1.0%, Cu: 0.6% or less (excluding 0%, the same shall apply hereinafter), Mn: 0.6 to 1.8%, Mg: more than 0.5% and 1.0% or less The ratio of Mn content to Si content (Mn% / Si%) is 2.0 or less, and the sacrificial anode material is made of an aluminum alloy composed of the remaining Al and impurities. 0%, Fe: 0.05-0.5%, Mn: 0.6-2.0%, Zn: 1.0-5.0%, Ni: 0.01-1.0%, The ratio of Mn content to Si content (Mn% / Si%) is 2.0 or more, and the aluminum alloy is composed of the balance Al and impurities. Strength and brazeability excellent aluminum alloy clad sheet, wherein the door. 2. A heat exchanger excellent in strength and brazing properties according to claim 1, wherein a sacrificial anode material is clad on one surface of the core material and an Al-Si brazing material is clad on the other surface. Aluminum alloy clad material. The Al—Si brazing material contains Si: 7-13%, Fe: 0.15-2.0%, Zn: 0.5-5.0%, Cu: 0.5-5. 1% or more of 0%, Sr: 0.005 to 0.1%, In: 0.05% or less, Sn: 0.05 or less, with the balance being Al and inevitable impurities 3. The aluminum alloy clad material for a heat exchanger having excellent strength and brazing properties according to claim 2. The aluminum alloy clad material for a heat exchanger having excellent strength and brazing properties according to claim 1, wherein a sacrificial anode material is clad on both surfaces of the core material. The said core material further contains 1 type or 2 types in Cr: 0.02-0.3%, Zr: 0.02-0.3%, The any one of Claims 1-4 characterized by the above-mentioned. Aluminum alloy clad material for heat exchangers with excellent strength and brazeability as described in 1. The aluminum alloy clad material for a heat exchanger excellent in strength and brazing according to any one of claims 1 to 5, wherein the core material further contains Ti: 0.05 to 0.35%. The core material further contains one or two of V: 0.01 to 0.3% and B: 0.01 to 0.3%. Aluminum alloy clad material for heat exchangers with excellent strength and brazeability as described in 1. The aluminum alloy clad for heat exchanger excellent in strength and brazeability according to any one of claims 1 to 7, wherein the sacrificial anode material further contains Ti: 0.01 to 0.35%. Wood. 9. The strength according to claim 1, wherein the sacrificial anode material further contains one or two of In: 0.05% or less and Sn: 0.05 or less. Aluminum alloy clad material for heat exchangers with excellent brazing properties. The aluminum alloy clad material for a heat exchanger excellent in strength and brazing according to any one of claims 1 to 9, wherein the core material has an average grain size after brazing heating of 200 µm or more. The aluminum alloy clad material for heat exchangers according to any one of claims 1 to 10, wherein the sacrificial anode material has an average grain size after brazing heating of 200 µm or less.

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