WO2023021915A1 - Aluminum alloy extruded tube and heat exchanger - Google Patents
Aluminum alloy extruded tube and heat exchanger Download PDFInfo
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- WO2023021915A1 WO2023021915A1 PCT/JP2022/028315 JP2022028315W WO2023021915A1 WO 2023021915 A1 WO2023021915 A1 WO 2023021915A1 JP 2022028315 W JP2022028315 W JP 2022028315W WO 2023021915 A1 WO2023021915 A1 WO 2023021915A1
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- Prior art keywords
- tube
- aluminum alloy
- heat exchanger
- brazing
- powder
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- 229910000838 Al alloy Inorganic materials 0.000 title claims abstract description 120
- 238000005219 brazing Methods 0.000 claims abstract description 113
- 239000000843 powder Substances 0.000 claims abstract description 100
- 230000004907 flux Effects 0.000 claims abstract description 89
- KRHYYFGTRYWZRS-UHFFFAOYSA-M Fluoride anion Chemical compound [F-] KRHYYFGTRYWZRS-UHFFFAOYSA-M 0.000 claims abstract description 69
- 238000000576 coating method Methods 0.000 claims abstract description 66
- 239000011248 coating agent Substances 0.000 claims abstract description 65
- 229910021364 Al-Si alloy Inorganic materials 0.000 claims abstract description 32
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- 238000012360 testing method Methods 0.000 claims description 25
- 238000010438 heat treatment Methods 0.000 claims description 19
- 239000013078 crystal Substances 0.000 claims description 14
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- 238000001816 cooling Methods 0.000 claims description 6
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Images
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K1/00—Soldering, e.g. brazing, or unsoldering
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K1/00—Soldering, e.g. brazing, or unsoldering
- B23K1/19—Soldering, e.g. brazing, or unsoldering taking account of the properties of the materials to be soldered
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K35/00—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting
- B23K35/22—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting characterised by the composition or nature of the material
- B23K35/24—Selection of soldering or welding materials proper
- B23K35/28—Selection of soldering or welding materials proper with the principal constituent melting at less than 950 degrees C
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C21/00—Alloys based on aluminium
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
- C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
- C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
- C22F1/04—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of aluminium or alloys based thereon
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F28—HEAT EXCHANGE IN GENERAL
- F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
- F28F19/00—Preventing the formation of deposits or corrosion, e.g. by using filters or scrapers
- F28F19/02—Preventing the formation of deposits or corrosion, e.g. by using filters or scrapers by using coatings, e.g. vitreous or enamel coatings
- F28F19/06—Preventing the formation of deposits or corrosion, e.g. by using filters or scrapers by using coatings, e.g. vitreous or enamel coatings of metal
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F28—HEAT EXCHANGE IN GENERAL
- F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
- F28F21/00—Constructions of heat-exchange apparatus characterised by the selection of particular materials
- F28F21/08—Constructions of heat-exchange apparatus characterised by the selection of particular materials of metal
Definitions
- the present invention relates to an aluminum alloy extruded tube used in a heat exchanger for automobiles and a heat exchanger made using the same.
- Automotive heat exchangers such as evaporators and condensers often use aluminum alloys that are lightweight and have high thermal conductivity.
- the heat exchanger has tubes through which a refrigerant flows and fins for exchanging heat between the refrigerant and the air outside the tubes, and the tubes and the fins are joined by brazing.
- a fluoride-based flux is often used for joining the tube and the fin.
- the tubes used in automotive heat exchangers are joined to fins by brazing in order to perform heat exchange, and it is necessary to provide a brazing material on the fin side or the tube side.
- a brazing filler metal is provided on the fin side
- the fins are produced using a clad material clad with a brazing filler metal, making it difficult to reduce manufacturing costs and material costs.
- a brazing material is provided on the tube side
- a technique has been proposed in which a flux layer containing Si powder, Zn-containing flux, and a binder is formed on the outer surface of the tube (Patent Document 1).
- the flux layer having the above composition can be deposited simultaneously with all of the brazing material component, Zn and flux component in one deposition step.
- the fin can be manufactured using a bare fin material. As a result, cost reduction can be achieved.
- flux components and Zn are generated according to the following reaction formula. 6KZnF3 + 4Al ⁇ 3KAlF4 + K3AlF6 + 6Zn (555°C or higher)
- the Zn-containing flux does not function as Zn and a flux component by itself, but by reacting with Al (aluminum) in the tube, Zn is precipitated and potassium fluoroaluminate, which is a flux component, is produced. , Zn and flux components.
- Patent Document 2 also proposes a technique using an alloy powder containing Si as a brazing powder.
- the pure Si powder contained in the paint melts the tube surface to generate liquid phase brazing, so in order to prevent the tube from penetrating during brazing, the tube must have a certain thickness or more. It is difficult to say that it contributes to the thinning of the tube.
- the pure Si powder contained in the paint forms a fillet when the Al-Si alloy liquid phase brazing produced by eutectic melting with the aluminum on the tube surface flows to the contact area between the fin and the tube. .
- the liquid phase brazing eutectic melted with the aluminum on the surface of the coarse Si grains and the tube surface quickly flows to the contact portion between the fin and the tube due to capillary action.
- the surroundings of the Si grains that have become smaller are separated from the tube surface, forming depressions on the tube surface where the liquid phase brazing flows out, and further eutectic melting progresses at the bottom of the depressions that are in contact with the Si grains. If so, a deep melted hole is formed, and there is a possibility that a through hole is generated in the tube body.
- Patent Document 1 the content of coarse grains that is five times or more the grain size (99% grain size, D99) at which the cumulative volume of grains having a grain size below that is 99% of all grains is less than 1 ppm.
- an Al-Si alloy powder is cited as an example of an alloy containing Si among brazing powders.
- Al--Si alloy powder is used as a brazing material for a coated tube, erosion occurs on the tube surface unlike the case of pure Si powder, and there is a concern that the tube may be thinned during brazing.
- a Zn-containing flux is used as the flux. Since the above-described flux reaction causes Zn to precipitate on the outer surface of the tube immediately before the liquid phase is generated, the generated liquid phase contains Zn at a high concentration.
- This Zn diffuses to the outer surface of the tube to form a Zn diffusion layer, which functions as a sacrificial anticorrosive layer to suppress the occurrence of pitting corrosion in the tube.
- the corrosion rate increases, and the thinning rate of the tube increases.
- Zn contained in the liquid phase during brazing also concentrates in the fillets formed between the fins and tubes.
- the fillet since the potential of the fillet becomes the most base, the fillet is preferentially corroded and worn when exposed to a corrosive environment, causing the fins to come off, resulting in early deterioration of the heat exchange performance and the fins. This means that premature penetration of the tube may occur due to the tube not being protected against corrosion.
- the present technology does not describe such countermeasures, and it is difficult to say that it is practical.
- the amount of surface Zn is usually 5 to 15 g/m 2 , which reduces the potential difference between the tube surface and the tube depth and reduces the corrosion rate. Therefore, when the amount of Zn is set to 5 g/m 2 or less in order to reduce the concentration of Zn on the fillet, it is difficult to spray Zn uniformly onto the tube surface.
- the object of the present invention is to join the fins and the tube without reducing the thickness of the tube during brazing or with a very small amount of reduction in thickness, and to have good brazeability and a long-term use.
- the present inventors have made intensive studies to solve the above problems, and as a result, in an aluminum alloy extruded tube having a tube body and a coating film applied to the tube surface, Al-Si is added to the outer surface of the tube.
- the tube surface is not melted or melted during brazing. Therefore, the thickness of the tube is not reduced during brazing, or the amount of reduction is very small, and a Zn diffusion layer is formed on the outer surface of the tube during brazing, so corrosion is prevented by the sacrificial anticorrosive layer and fins on the tube surface layer.
- the present inventors have completed the present invention by discovering that the corrosion resistance is excellent.
- the present invention (1) is an aluminum alloy extruded tube used in a heat exchanger for automobiles, a tube body made of an aluminum alloy containing Mn; a coating film formed on the surface of the tube body; has The coating contains Al—Si alloy brazing powder, Zn-containing fluoride-based flux powder, Zn-free fluoride-based flux powder, and a binder,
- the coating amount of the Al—Si alloy brazing filler metal powder is 9.0 to 25.0 g/m 2
- the coating amount of the Zn-containing fluoride flux powder is 1.0 to 9.0 g/m 2
- the coating amount of the Zn-free fluoride-based flux powder is 1.0 to 11.0 g/m 2
- the coating amount of the binder is 1.0 to 13.0 g/m 2 ;
- To provide an aluminum alloy extruded tube for a heat exchanger characterized by:
- the present invention (2) is characterized in that the aluminum alloy contains 0.20 to 1.20% by mass of Mn and 0.10% by mass or less of Ti, and the balance is Al and unavoidable impurities.
- the present invention provides an aluminum alloy extruded tube for a heat exchanger according to (1).
- the average crystal grain size of the tube body after the heating test is held at 600° C. ⁇ 10° C. for 3 minutes and cooled to room temperature to measure the average crystal grain size of 150 ⁇ m or more.
- An aluminum alloy extruded tube for a heat exchanger according to any one of (1) to (3) is provided.
- the present invention (5) is characterized in that the heat exchanger aluminum alloy extruded tube according to any one of (1) to (4) and a fin made of an aluminum alloy containing Zn are joined by brazing.
- the present invention provides a heat exchanger that
- the present invention (6) comprises an aluminum alloy extruded tube made of an aluminum alloy containing Mn, and a fin brazed to the aluminum extruded tube and made of an aluminum alloy containing Zn,
- the aluminum alloy extruded tube has a Zn diffusion layer on the tube surface,
- the potential difference between the tube surface and the tube depth of the aluminum alloy extruded tube is -180 to -40 mV,
- the fins and the tube are joined without reducing the thickness of the tube during brazing or with a very small amount of reduction in thickness, and the brazeability is good, and it can be used for a long time.
- the fins are difficult to fall off, and the Zn diffusion layer as a sacrificial corrosion protection layer is formed on the tube surface layer by brazing, and corrosion is prevented by the sacrificial corrosion protection layer on the tube surface layer and the fins, resulting in excellent corrosion resistance. It is possible to provide an aluminum alloy extruded tube used for and a heat exchanger using the extruded tube.
- FIG. 4 is a schematic diagram showing a mini-core produced in an example.
- the aluminum alloy extruded tube of the present invention is an aluminum alloy extruded tube used in a heat exchanger for automobiles, a tube body made of an aluminum alloy containing Mn; a coating film formed on the surface of the tube body; has The coating contains Al—Si alloy brazing powder, Zn-containing fluoride-based flux powder, Zn-free fluoride-based flux powder, and a binder,
- the coating amount of the Al—Si alloy brazing filler metal powder is 9.0 to 25.0 g/m 2
- the coating amount of the Zn-containing fluoride flux powder is 1.0 to 9.0 g/m 2
- the coating amount of the Zn-free fluoride-based flux powder is 1.0 to 11.0 g/m 2 and the coating amount of the binder is 1.0 to 13.0 g/m 2 ;
- An aluminum alloy extruded tube for a heat exchanger characterized by
- the extruded tube for a heat exchanger of the present invention is made of an aluminum alloy, and is an aluminum alloy tube produced by extruding an aluminum alloy.
- the aluminum alloy extruded tube of the present invention is brazed with fins or the like to be used as a tube through which a refrigerant flows in a heat exchanger for automobiles.
- the tube body according to the aluminum alloy extruded tube of the present invention is made of an aluminum alloy containing Mn.
- Mn has the effect of improving the strength by forming a solid solution in the aluminum matrix, and also has the effect of making the potential noble.
- the Mn-containing aluminum alloy that forms the tube body contains 0.20 to 1.20% by mass of Mn, has a Ti content of 0.10% by mass or less, and the balance is Al and inevitable impurities. is preferred.
- the Mn content is preferably 0.20 to 1.20% by mass, particularly preferably 0.40 to 1.20% by mass.
- the Mn content in the Mn-containing aluminum alloy is within the above range, it is possible to obtain a sufficient strength improvement effect and potential noble effect in the deep portion of the tube.
- the Mn content in the aluminum alloy is less than the above range, it is difficult to obtain the above effects.
- the Ti content in the Mn-containing aluminum alloy forming the tube body is preferably 0.10% by mass or less, more preferably 0.001 to 0.08% by mass.
- the structure can be refined during casting.
- the Ti content in the aluminum alloy exceeds the above range, large crystals may form during casting, making it difficult to produce a healthy tube body. , the crystallized Ti may cause friction with the die, which may reduce productivity and tool life.
- an aluminum alloy ingot adjusted to the chemical composition of the aluminum alloy containing Mn and cast that is, 0.20 to 1.20% by mass, preferably 0.40 to 1.20% by mass of Mn, Ti content is 0.10% by mass or less, preferably 0.001 to 0.08% by mass, and the balance is Al and inevitable impurities
- An aluminum alloy ingot is subjected to the following homogenization treatment It is preferably an aluminum alloy subjected to hot extrusion.
- the homogenization treatment includes the following first form of homogenization treatment and second form of homogenization treatment.
- an aluminum alloy ingot having a predetermined chemical composition is held at 400-650°C for 2 hours or longer.
- the treatment temperature in the first form of homogenization treatment is 400-650°C, preferably 430-620°C.
- the treatment temperature of the homogenization treatment is within the above range, coarse crystallized substances formed during casting can be decomposed or granulated, and uneven structures such as segregation layers generated during casting can be homogenized. can.
- resistance during extrusion can be reduced to improve extrudability, and the surface roughness of the product after extrusion can be reduced.
- the treatment temperature of the homogenization treatment is less than the above range, there is a risk that coarse crystallized substances and the uneven structure described above will remain, which may lead to deterioration in extrusion performance and increase in surface roughness. Moreover, if the above range is exceeded, there is a risk of inducing melting of the ingot.
- the treatment time for the homogenization treatment is 2 hours or more, preferably 5 hours or more. Homogenization becomes sufficient when the treatment time of the homogenization treatment is within the above range. Moreover, even if the treatment time of the homogenization treatment exceeds 24 hours, the effect of homogenization is saturated, so 24 hours or less is preferable.
- an aluminum alloy ingot having a predetermined chemical composition is subjected to a first homogenization treatment of holding at 550 to 650 ° C. for 2 hours or more, and after performing the first homogenization treatment, A second homogenization treatment is performed by holding the aluminum alloy ingot at 400 to 550° C. for 3 hours or longer.
- the treatment temperature in the first homogenization treatment of the second form of homogenization treatment is 550-650°C, preferably 580-620°C.
- the treatment temperature of the first homogenization treatment is within the above range, coarse crystallized substances formed during casting can be decomposed or granulated, and can be positively redissolved.
- the treatment temperature of the first homogenization treatment is less than the above range, re-dissolution will be difficult to progress, and if it exceeds the above range, the ingot may melt.
- the treatment time of the first homogenization treatment is 2 hours or more, preferably 5 hours or more. When the treatment time of the homogenization treatment is within the above range, the above effects are sufficient. Moreover, even if the treatment time of the homogenization treatment exceeds 24 hours, the effect of homogenization is saturated, so 24 hours or less is preferable.
- the treatment temperature in the second homogenization treatment according to the second form of homogenization treatment is 400 to 550°C.
- the treatment temperature of the second homogenization treatment is within the above range, Mn dissolved in the matrix phase can be precipitated and the solid solubility of Mn can be reduced. As a result, deformation resistance in extrusion processing can be reduced, and extrudability can be improved.
- the treatment temperature of the second homogenization treatment is less than the above range, the amount of precipitation of Mn is reduced, so the effect of reducing deformation resistance may be insufficient. Since it becomes difficult for Mn to precipitate, there is a risk of increasing the deformation resistance.
- the treatment time of the second homogenization treatment is 3 hours or more, preferably 5 hours or more.
- the treatment time of the second homogenization treatment is less than the above range, the precipitation of Mn may be sufficient, and the effect of lowering the deformation resistance may be insufficient.
- the first homogenization treatment and the second homogenization treatment may be performed continuously, or after performing the first homogenization treatment, the ingot is once After cooling, a second homogenization treatment may be performed.
- performing the first homogenization treatment and the second homogenization treatment continuously means that after the first homogenization treatment is completed, the temperature of the ingot is set to a temperature lower than the treatment temperature of the second homogenization treatment It means that the second homogenization treatment is started when the treatment temperature of the second homogenization treatment is reached without cooling to .
- the second homogenization treatment is started when the treatment temperature of the second homogenization treatment is reached without cooling to .
- the second homogenization treatment is performed, for example, after performing the first homogenization treatment, the ingot is heated to 200 ° C. After cooling to below, it is reheated and the second homogenization treatment is performed.
- the method of hot-extrusion processing the aluminum alloy ingot that has been subjected to the first form of homogenization treatment or the second form of homogenization treatment is not particularly limited.
- the processing temperature for hot extrusion processing is, for example, 400 to 550°C.
- the shape of the tube body is not particularly limited, and is appropriately selected according to the application and required properties.
- the tube main body include an extruded flat multi-hole tube formed by extrusion, having a plurality of coolant channels inside, and having a flat cross-sectional shape perpendicular to the extrusion direction.
- the tube main body may have a shape such as a simple cylindrical shape, for example.
- the tubular tube may be manufactured by extrusion.
- the coating film according to the aluminum alloy extruded tube of the present invention is formed on the outer surface of the tube.
- the coating contains Al—Si alloy brazing powder, Zn-containing fluoride-based flux powder, Zn-free fluoride-based flux powder, and a binder.
- the Al-Si alloy brazing powder is an alloy of powdered Al and Si.
- the Al--Si alloy brazing material powder melts by itself when heated during brazing, and produces liquid-phase brazing on the outer surface of the tube. This allows the tube to be joined to the fins and headers. Since the Al—Si alloy brazing filler metal powder contains Al, the outer surface of the tube is less likely to be melted by the brazing filler metal during brazing.
- the content of Si in the Al-Si alloy constituting the Al-Si alloy brazing powder is preferably 5.0 to 20.0% by mass, particularly preferably 7.0 to 15.0% by mass.
- the content of Si in the alloy of Al and Si is within the above range, it is difficult for the outer surface of the tube to melt during brazing to reduce the thickness of the tube, and the brazeability is improved.
- the coating amount of the Al—Si alloy brazing powder is 9.0 to 25.0 g/m 2 , preferably 12.0 to 20.0 g/m 2 .
- the amount of the Al—Si alloy brazing filler metal powder applied is within the above range, good brazeability is obtained.
- the coating amount of the Al—Si alloy brazing material powder is less than the above range, the amount of the liquid phase brazing filler metal will be insufficient, and joint failure will easily occur. It becomes excessively thick, causing dimensional changes in the core after brazing, and the brazeability tends to be low.
- Zn-containing fluoride-based flux generates Zn by reacting with Al in the tube during brazing heat, forming a Zn diffusion layer on the tube surface.
- Zn-free fluoride flux is produced at the same time.
- the Zn-free fluoride-based flux melts during the brazing heat and destroys the Al-Si alloy powder and the oxide film on the outer surface of the tube in advance, enabling brazing to proceed immediately after the formation of liquid phase brazing. do.
- the terms "containing Zn" and "containing Zn” indicate that the amount of Zn is detected (beyond the lower limit of detection) in analysis using an electron probe microanalyzer.
- Zn-containing fluoride-based flux powders examples include KZnF 3 and ZnF 2 .
- the coating amount of the Zn-containing fluoride-based flux powder is 1.0 to 9.0 g/m 2 , preferably 2.0 to 8.0 g/m 2 .
- the heat exchanger has excellent corrosion resistance.
- the coating amount of the Zn-containing fluoride-based flux powder is less than the above range, the potential difference between the surface of the tube after brazing heat and the depth of the tube becomes small, resulting in an insufficient sacrificial anode effect. If the range is exceeded, the potential difference between the tube surface and the tube depth becomes excessively large, which increases the rate of thinning of the tube and increases the degree of Zn concentration in the fillet, resulting in a decrease in corrosion resistance.
- the Zn-free fluoride-based flux powder functions as a flux during brazing, melts during brazing addition heat, destroys the Al-Si alloy brazing powder and the oxide film on the outer surface of the tube, and after the formation of liquid phase brazing, Allows brazing to proceed immediately.
- the Zn-free fluoride-based flux powder is powdery fluoride containing no Zn.
- "no Zn" or “no Zn” means that the amount of Zn is below the detection limit in analysis by an electron probe microanalyzer.
- Zn-free fluoride constituting the Zn-free fluoride flux powder examples include K--Al--F compounds such as KAlF 4 , K 2 AlF 5 and K 3 AlF 6 .
- Zn-free fluorides include fluxes such as CaF 2 and LiF.
- the coating amount of the Zn-free fluoride-based flux powder is 1.0 to 11.0 g/m 2 , preferably 3.0 to 11.0 g/m 2 .
- the coating amount of the Zn-free fluoride-based flux powder is within the above range, the effect of destroying the oxide film during brazing is sufficient.
- the coating amount of the Zn-free fluoride-based flux powder is less than the above range, the flux component will be insufficient, resulting in insufficient destruction of the oxide film, and the brazability will tend to be low. If it exceeds, the coating thickness becomes excessively thick, the dimensional change of the core after brazing occurs, and the brazeability tends to deteriorate.
- the total coating amount of the Zn-containing fluoride-based flux powder and the coating amount of the Zn-free fluoride-based flux powder is preferably 3.0 to 15.0 g/m 2 . Particularly preferred is 0 to 13.0 g/m 2 . Sufficient brazability can be obtained by setting the total coating amount of the Zn-containing fluoride-based flux powder and the coating amount of the Zn-free fluoride-based flux powder within the above range.
- the total coating amount of the Zn-containing fluoride-based flux powder and the coating amount of the Zn-free fluoride-based flux powder is less than the above range, the flux component will be insufficient, resulting in insufficient destruction of the oxide film and soldering.
- the above range is exceeded, the effect of destroying the oxide film described above is saturated, but the change in the coating thickness after melting the flux becomes excessively large, so the core during brazing dimensional change, and there is a concern that the brazeability may deteriorate.
- the binder adheres Al-Si alloy brazing powder, Zn-containing fluoride-based flux powder, and Zn-free fluoride-based flux powder to the surface of the tube body.
- binders include acrylic resins and urethane resins.
- the coating amount of the binder is 1.0 to 13.0 g/m 2 .
- the coating amount of the binder is within the above range, the Al—Si alloy brazing powder, the Zn-containing fluoride flux powder, and the Zn-free fluoride flux powder can be adhered well to the surface of the tube body. .
- the coating amount of the binder is less than the above range, the coating film tends to peel off. may remain and the brazability may deteriorate.
- a coating film on the surface of the tube body for example, Al—Si alloy brazing powder, Zn-containing fluoride-based flux powder, Zn-free fluoride-based flux powder, and a binder are mixed with a solvent, A coating film can be formed by applying the obtained paste to the surface of the tube body and then drying and removing the solvent. Before mixing the Al—Si alloy brazing filler metal powder, the Zn-containing fluoride flux powder, and the Zn-free fluoride flux powder in the solvent, the Al—Si alloy brazing filler metal powder and the Zn-containing fluoride flux are mixed in advance.
- Powder and Zn-free fluoride-based flux powder are mixed to form a mixed powder of Al—Si alloy brazing powder, Zn-containing fluoride-based flux powder, and Zn-free fluoride-based flux powder.
- the mixed powder obtained may be mixed in a solvent together with a binder.
- a roll coating method or the like is used to apply the paste to the surface of the tube body.
- the surface of the aluminum alloy extruded tube after brazing and the tube depth is preferably -180 to -40 mV, particularly preferably -150 to -40 mV.
- a Zn diffusion layer is formed on the tube surface by the coating containing the Zn-containing fluoride-based flux powder, so that a potential difference is formed between the tube surface and the deep part of the tube.
- the electric potential at the tube depth of the aluminum alloy extruded tube refers to the electric potential at a depth of 150 ⁇ m or more from the surface of the aluminum alloy extruded tube after brazing.
- the aluminum alloy extruded tube for a heat exchanger of the present invention is preferably kept at 600 ° C. ⁇ 10 ° C. for 3 minutes, cooled to room temperature, and then cooled to room temperature.
- the average grain size is 150 ⁇ m or more.
- the aluminum alloy extruded tube for a heat exchanger has a crystal structure such that the tube body has an average crystal grain size of 150 ⁇ m or more when it is held at 600° C. ⁇ 10° C. for 3 minutes and cooled to room temperature.
- the aluminum alloy extruded tube for a heat exchanger was kept at 600°C ⁇ 10°C for 3 minutes, and after cooling to room temperature, a heating test was conducted to measure the average crystal grain size.
- the heating test related to the aluminum alloy extruded tube for heat exchanger first, the aluminum alloy extruded tube for heat exchanger is heated to raise the temperature, and in the temperature raising process, it is heated to a holding temperature of 600 ° C. ⁇ 10 ° C., and then In this test, a temperature of 600° C. ⁇ 10° C. is maintained for 3 minutes, and then a heating test is performed by cooling to room temperature, and then the average crystal grain size of the tube body of the aluminum alloy extruded tube for heat exchanger is measured after the heating test.
- the method for measuring the average crystal grain size of the tube body includes a method of electropolishing a test piece, obtaining a microscopic image of each cross section with a polarizing microscope at a magnification of 50 to 100, and measuring the equivalent circle diameter. be done.
- the temperature range up to 500 ° C. is an average temperature increase rate of 30 ⁇ 10 ° C./min
- the temperature range of 500 ° C. or higher is an average of 10 ⁇ 5 ° C./min. is the rate of temperature rise.
- the aluminum alloy extruded tube for a heat exchanger of the present invention has a tube main body made of the above specific aluminum alloy. Therefore, the aluminum alloy extruded tube for a heat exchanger of the present invention has higher strength characteristics than when a pure aluminum alloy is used for the tube body.
- the coating film of the aluminum alloy extruded tube for heat exchangers of the present invention contains Al-Si alloy powder, Zn-containing fluoride flux powder, and Zn-free fluoride flux powder. These powders exert their respective characteristics and interact with each other to exert a synergistic effect, thereby easily realizing excellent brazeability and corrosion resistance.
- the Al—Si alloy powder contained in the mixed powder is melted by heating during brazing, and liquid phase brazing is generated on the outer surface of the tube.
- the heat exchanger tubes and the fins can be joined.
- the thickness of the tube should not be reduced during brazing, or the amount of reduction is very small, and a thinner tube should be used. can be done.
- the aluminum alloy extruded tube for heat exchanger of the present invention contains 1.0 to 9.0 g/m 2 , preferably 2.0 to 8.0 g/m 2 of Zn-containing fluoride-based flux powder in the coating film.
- Zn-containing fluoride-based flux powder in the coating film.
- the amount of Zn when the amount of Zn is large, the Zn concentration in the fillets, which are joints formed on the tube surface by brazing, increases, and the fillets are preferentially corroded, which may lead to premature detachment of the fins.
- the tube surface in the case of a heat exchanger tube having a coating film formed by applying a paint containing Zn-containing fluoride-based flux powder, the tube surface should be uniformly coated regardless of the amount of Zn-containing fluoride-based flux. Therefore, an appropriate amount of Zn can be applied to the tube surface.
- an appropriate potential difference is formed between the tube surface and the tube core, and the tube itself can have excellent anti-corrosion performance.
- Zn concentration in fillets is reduced, and corrosion resistance is improved.
- the aluminum alloy extruded tube for a heat exchanger of the present invention contains a Zn-containing fluoride-based flux powder and a Zn-free fluoride-based flux powder in the coating film, and the Zn-containing fluoride-based flux powder and the Zn-free fluoride
- the system flux powder is melted by heating during brazing, and destroys the oxide film on the surface of the brazing material powder and the oxide film on the outer surface of the tube first, making it possible to braze immediately after melting the Al-Si alloy powder. do.
- the Zn-free fluoride-based flux powder is used to form the oxide film on the surface of the brazing material powder and the oxide film on the outer surface of the tube, which are insufficient with the Zn-containing fluoride-based flux powder alone. Since it replenishes the destructive action, the potential difference between the surface of the tube after brazing and the deep part of the tube can be made appropriate, and while the concentration of Zn in the fillet during brazing is reduced, the brazeability can be improved.
- the aluminum alloy extruded tube for a heat exchanger of the present invention does not or hardly causes melting of the outer surface even if it is thinner, and has excellent brazeability.
- Zn-containing fluoride-based flux powder contained in the coating reacts with the tube during brazing addition heat to generate Zn, and Zn diffuses from the tube surface to sacrifice It has a layer and exhibits a sacrificial anti-corrosion effect as a single tube, and at the same time, Zn concentration in the fillet is reduced, and it has excellent corrosion resistance.
- Heat exchanger A heat exchanger according to a first aspect of the present invention is obtained by brazing fins made of an aluminum alloy containing Zn and extruded aluminum alloy tubes for a heat exchanger of the present invention.
- the fins made of an aluminum alloy containing Zn according to the heat exchanger of the first embodiment of the present invention are made of an aluminum alloy.
- the aluminum alloy forming the fin material is not particularly limited as long as it has sufficient strength and corrosion resistance for use in heat exchangers. 0.50 to 2.50% by mass, a Cu content of 0.30% by mass or less, and the balance being Al and unavoidable impurities.
- the aluminum alloy for fin material may further contain 1.50% by mass or less of Si and/or 0.30% by mass or less of Zr.
- the fins made of an aluminum alloy containing Zn according to the heat exchanger of the present invention may be known fins as long as they have sufficient strength and corrosion resistance for use in heat exchangers.
- the heat exchanger of the first aspect of the present invention after contacting the aluminum alloy extruded tube for heat exchanger of the present invention with fins made of an aluminum alloy containing Zn, other members such as a header are assembled, It is produced by heating and brazing these.
- the heating temperature, heating time, and atmosphere for brazing are not particularly limited, and the brazing method is also not particularly limited.
- the heating temperature for brazing is, for example, 590 to 610° C.
- the heating time for brazing is, for example, 15 minutes to 45 minutes
- the atmosphere for brazing is, for example, nitrogen gas atmosphere, argon A gas atmosphere or the like.
- the potential difference between the tube surface and the tube depth of the aluminum alloy extruded tube is -180 to -40 mV, It is preferably -150 to -40 mV. Since the potential difference between the tube surface and the tube depth of the aluminum alloy extruded tube is within the above range, the Zn diffusion layer formed near the tube surface of the extruded tube exhibits a sufficient sacrificial anti-corrosion effect, making the tube excellent as a single unit. It has anti-corrosion performance.
- the heat exchanger of the first aspect of the present invention is brazed using the aluminum alloy extruded tube for heat exchanger of the present invention as a tube material, so that the thickness of the tube is not reduced during brazing. It is joined to the fin with a very small decrease in thickness. Therefore, the heat exchanger of the present invention has high strength even if it is thin. In addition, since the potential difference between the surface of the tube after brazing and the depth of the tube is appropriate, pitting corrosion is suppressed by the sacrificial anode effect, but the rate of thinning of the tube is not too fast, providing excellent corrosion resistance.
- the heat exchanger tubes of the present invention and fins made of an aluminum alloy containing Zn are joined by brazing.
- a fillet is formed between the tube and the fins during brazing.
- Zn in the molten brazing filler metal is concentrated during fillet formation as described above, and the potential of the fillet becomes the most negative.
- corrosion progresses most rapidly in the fillet portions, and the disappearance of the fillets causes the fins to come off the tube surface.
- the heat exchange performance is greatly reduced, and furthermore, the anti-corrosion action of the tube by the fins is lost, so that the tube may penetrate at an early stage.
- the Zn component is contained in the coating film applied to the aluminum alloy extruded tube for heat exchanger
- Zn concentration in the fillet does not occur as compared with the conventional technology. That is, since the fillets do not corrode preferentially, the fins do not fall off from the tube surface for a long period of time, and not only is it possible to prevent deterioration in heat exchange performance, but the fins provide a long-term anti-corrosion effect on the tube. Therefore, as described above, it has excellent corrosion resistance even when exposed to a severe corrosive environment.
- the aluminum alloy extruded tube has a Zn diffusion layer on the tube surface,
- the potential difference between the tube surface and the tube depth is -180 to -40 mV,
- the aluminum alloy extruded tube according to the second aspect of the heat exchanger of the present invention is made of an aluminum alloy containing Mn, and the Mn content in the aluminum alloy extruded tube according to the second aspect of the heat exchanger of the present invention is is preferably 0.20 to 1.20% by weight, particularly preferably 0.40 to 1.20% by weight. Further, the aluminum alloy extruded tube according to the second aspect of the heat exchanger of the present invention can contain Ti, and the Ti content in the aluminum alloy extruded tube according to the second aspect of the heat exchanger of the present invention is The amount is preferably 0.10% by weight or less, particularly preferably 0.001 to 0.08% by weight. Also, the aluminum alloy extruded tube according to the second embodiment of the heat exchanger of the present invention has a Zn diffusion layer on the tube surface.
- the aluminum alloy forming the fin material of the heat exchanger according to the second embodiment of the present invention is not particularly limited as long as it has sufficient strength and corrosion resistance for heat exchangers. is 0.80 to 2.00% by mass, the Zn content is 0.50 to 2.50% by mass, and the Cu content is 0.30% by mass or less.
- the aluminum alloy for fin material may contain 1.50% by mass or less of Si and/or 0.30% by mass or less of Zr.
- the potential difference between the tube surface and the tube depth of the aluminum alloy extruded tube is -180 to -40 mV, It is preferably -150 to -40 mV. Since the potential difference between the tube surface and the tube depth of the aluminum alloy extruded tube is within the above range, the Zn diffusion layer formed near the tube surface of the extruded tube exhibits a sufficient sacrificial anti-corrosion effect, making the tube excellent as a single unit. It has anti-corrosion performance.
- Examples and Comparative Examples A tube body was produced using an alloy having the chemical components shown in Table 1, and then a coating film having a composition shown in Table 2 was formed on the surface of the obtained tube body to produce an aluminum alloy extruded tube. After that, using the obtained aluminum alloy extruded tube, a mini-core simulating a heat exchanger as shown in FIG. 1 was assembled, and the corrosion resistance of the obtained three types of mini-cores was evaluated.
- a billet having the chemical components shown in Table 1 was heated at 600° C. for 10 hours for homogenization. After the homogenized billet was cooled to room temperature, it was reheated to 450° C. and subjected to hot extrusion. As described above, a tube body having a width of 16 mm, a height of 1.0 mm, a flat cross section perpendicular to the extrusion direction, and a plurality of coolant channels was produced.
- a paste for forming a coating film was prepared separately from the production of the tube body. Al--Si alloy brazing powder, Zn-free fluoride flux powder, Zn-containing fluoride flux powder and a binder were mixed with a solvent to prepare a paste for forming a coating film. Next, the obtained paste was applied to the flat surface of the tube body using a roll coater to obtain a coated tube.
- the composition of the paste after coating was as shown in Table 2.
- the Al—Si alloy brazing filler metal powder has a Si content of 12.00% by mass
- the Zn-free fluoride-based flux powder is a K—Al—F-based flux
- the Zn-containing fluoride-based flux is It was KZnF3 and the binder was an acrylic resin.
- a 0.1 mm thick plate made of an aluminum alloy containing Mn: 1.20% by mass and Zn: 1.50% by mass was corrugated to produce a fin having a corrugated shape.
- the fin pitch was 3 mm and the fin height was 7 mm.
- ⁇ Mini-core preparation and heating test> The upper and lower fins were laminated in such a manner that they were sandwiched between aluminum alloy extruded tubes, and assembled into a predetermined shape shown in FIG. In this state, in a nitrogen gas atmosphere, the temperature of the tube and fins was raised to 600°C at an average heating rate of 10°C per minute in the region of 400°C or higher, and the temperature was maintained at 600°C for 3 minutes, and then cooled to room temperature. By brazing, the tube cut to a length of 40 mm and the fins were joined to obtain a mini-core simulating a heat exchanger. Note that the thermal history for producing the mini-core corresponds to the thermal history of the heating test.
- ⁇ Brazability evaluation> The cross section of the brazed tube was observed, and by visual observation, the bonding state of the fins, the presence or absence of appearance defects such as discoloration, the presence or absence of melting of the fins, and the presence or absence of erosion on the tube surface were determined. Etching was also performed, and the average crystal grain size was measured. The average crystal grain size is measured by electropolishing the tube surface and then using a polarizing microscope with a magnification of 25 to obtain a microscopic image of a cross section at a depth of 10 ⁇ m or less from the tube surface. Three 1 mm line segments were drawn, and the average value obtained by dividing the 1 mm length of the line segment by the number of grain boundaries intersecting each line segment was taken as the average grain size.
- Table 3 shows the brazeability evaluation results. Test Examples A, B, and C did not cause any brazing defects and passed the brazing properties. In addition, the average grain size of the post-brazing structure was sufficiently large as 150 ⁇ m or more, and no erosion occurred, which was acceptable. In addition, since the wall thickness of the tube after brazing did not change significantly compared to the wall thickness before brazing, it was confirmed that significant melting did not occur.
- Table 4 shows the self-potential measurement results and the corrosion test results.
- the natural potential of the tube surface is 40 mV or more less noble than the deep part of the tube, the corrosion of the deep part of the tube can be prevented by preferential corrosion of the tube surface, and the natural potential of the tube surface and the natural potential of the deep part of the tube The difference was within 180 mV, the natural potential of the tube surface was not too base than the depth of the tube, and the potential difference was moderate.
- Test Example A the peeling of the fins was extremely slight, and the sample passed the test. Specimen B was accepted because the fin peeling was slight.
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Abstract
Provided is an aluminum alloy extruded tube for a heat exchanger, characterized by having a tube body composed of an Mn-containing aluminum alloy and a coating film formed on the surface of the tube body, and the coating film being such that the coating amount of an Al-Si alloy brazing material powder is 9.0-25.0 g/m2, the coating amount of a Zn-containing fluoride-based flux powder is 1.0-9.0 g/m2, the coating amount of a Zn-free fluoride-based flux powder is 1.0-11.0 g/m2, and the coating amount of a binder is 1.0-13.0 g/m2, By using the present invention, it is possible to provide: an extruded tube that is to be used in a heat exchanger for an automobile, the extruded tube being joined to fins without any reduction in the wall thickness of the tube or with extremely little reduction in said wall thickness, having excellent brazing capabilities, having exceptional corrosion resistance, and being such that the fins do not readily fall out for a long period of time; and a heat exchanger in which said extruded tube is used.
Description
本発明は、自動車用熱交換器に用いられるアルミニウム合金製の押出チューブ及びそれを用いて作製された熱交換器に関する。
The present invention relates to an aluminum alloy extruded tube used in a heat exchanger for automobiles and a heat exchanger made using the same.
エバポレータ、コンデンサ等の自動車用熱交換器には、軽量であり、高い熱伝導性を有するアルミニウム合金が多用されている。熱交換器は、冷媒が流通するチューブと、冷媒とチューブ外側の空気との間で熱交換するためのフィンとを有しており、チューブとフィンとがろう付により接合されている。チューブとフィンとの接合には、フッ化物系のフラックスを用いることが多い。
Automotive heat exchangers such as evaporators and condensers often use aluminum alloys that are lightweight and have high thermal conductivity. The heat exchanger has tubes through which a refrigerant flows and fins for exchanging heat between the refrigerant and the air outside the tubes, and the tubes and the fins are joined by brazing. A fluoride-based flux is often used for joining the tube and the fin.
自動車用熱交換器に用いられるチューブは、前述の通り熱交換を行うために、ろう付によりフィンと接合され、フィン側またはチューブ側にろう材を設ける必要がある。フィン側にろう材を設ける場合、ろう材がクラッドされたクラッド材を用いてフィンが作製され、製造コストや材料コストの低減が困難である。チューブ側にろう材を設ける場合、例えばチューブの外表面に、Si粉末とZn含有フラックスとバインダとが含まれてなるフラックス層を形成させる技術が提案されている(特許文献1)。上記の組成を有するフラックス層は、ろう材成分、Zn及びフラックス成分の全てを一度の付着工程で同時に付着させることができる。また、フィン側にろう材を設ける必要がないため、ベアフィン材を用いてフィンを作製することができる。これらの結果、コスト低減を図ることができる。
As mentioned above, the tubes used in automotive heat exchangers are joined to fins by brazing in order to perform heat exchange, and it is necessary to provide a brazing material on the fin side or the tube side. When a brazing filler metal is provided on the fin side, the fins are produced using a clad material clad with a brazing filler metal, making it difficult to reduce manufacturing costs and material costs. When a brazing material is provided on the tube side, for example, a technique has been proposed in which a flux layer containing Si powder, Zn-containing flux, and a binder is formed on the outer surface of the tube (Patent Document 1). The flux layer having the above composition can be deposited simultaneously with all of the brazing material component, Zn and flux component in one deposition step. Moreover, since there is no need to provide a brazing material on the fin side, the fin can be manufactured using a bare fin material. As a result, cost reduction can be achieved.
例えばKZnF3をZn含有フラックスとして含むフラックス層を用いる場合、以下の反応式によりフラックス成分及びZnが生成される。
6KZnF3+4Al→3KAlF4+K3AlF6+6Zn (555℃以上) For example, when using a flux layer containing KZnF3 as a Zn-containing flux, flux components and Zn are generated according to the following reaction formula.
6KZnF3 + 4Al→ 3KAlF4 + K3AlF6 + 6Zn (555°C or higher)
6KZnF3+4Al→3KAlF4+K3AlF6+6Zn (555℃以上) For example, when using a flux layer containing KZnF3 as a Zn-containing flux, flux components and Zn are generated according to the following reaction formula.
6KZnF3 + 4Al→ 3KAlF4 + K3AlF6 + 6Zn (555°C or higher)
上記反応式から、Zn含有フラックスは、単体ではZn及びフラックス成分としては機能せず、チューブのAl(アルミニウム)との反応によりZnを析出すると共にフラックス成分であるフルオロアルミン酸カリウムを生成することにより、Zn及びフラックス成分として機能する。
From the above reaction formula, the Zn-containing flux does not function as Zn and a flux component by itself, but by reacting with Al (aluminum) in the tube, Zn is precipitated and potassium fluoroaluminate, which is a flux component, is produced. , Zn and flux components.
特許文献2では、ろう材粉末としてSiを含む合金粉末を使用した技術も提案されている。
Patent Document 2 also proposes a technique using an alloy powder containing Si as a brazing powder.
近年、環境負荷を低減させるために、構成部品の軽量化により自動車の燃費を向上させる要求や、部品の長寿命化により製品としての材料使用量を低減する要求が高まっている。かかる観点から、従来よりも肉厚の薄いチューブを用いることや、そのようなチューブを用いた熱交換器において従来よりも高い耐食性を有することが強く求められている。このことは、チューブの薄肉化が可能であることだけでなく、チューブ自体が優れた犠牲防食作用を有することと同時に、腐食環境にさらされた後でもフィンがチューブ表面から脱落することなく、長い期間に亘ってチューブ表面を防食する必要があることを意味する。
In recent years, in order to reduce the environmental impact, there has been an increasing demand to improve the fuel efficiency of automobiles by reducing the weight of component parts, and to reduce the amount of materials used in products by extending the life of parts. From this point of view, it is strongly demanded to use thinner tubes than conventional ones and to have higher corrosion resistance than conventional ones in heat exchangers using such tubes. This means not only that the tube can be made thinner, but also that the tube itself has an excellent sacrificial anti-corrosion effect. This means that it is necessary to protect the tube surface from corrosion over a period of time.
しかしながら、特許文献1の手法では、塗料中に含まれる純Si粉末がチューブ表面を溶融させて液相ろうを生成することから、ろう付中のチューブ貫通を防ぐためにチューブ肉厚を一定以上確保する必要があり、チューブの薄肉化に貢献するとは言い難い。
However, in the method of Patent Document 1, the pure Si powder contained in the paint melts the tube surface to generate liquid phase brazing, so in order to prevent the tube from penetrating during brazing, the tube must have a certain thickness or more. It is difficult to say that it contributes to the thinning of the tube.
さらに、塗料中に含まれる純Si粉末は、チューブ表面のアルミニウムと共晶溶融して生成するAl-Si合金の液相ろうがフィンとチューブの接触部に流動してフィレットを形成することになる。このとき、粗大なSi粒が混入していると、粗大なSi粒の表面とチューブ表面のアルミニウムと共晶溶融した液相ろうが毛細管現象によって速やかにフィンとチューブの接触部に流動するため、小さくなったSi粒の周囲がチューブ表面から離れ、液相ろうが流出したチューブ表面に凹み部を形成し、Si粒と接する凹み部の底でさらなる共晶溶融が進行することになる。そうすると深い溶融穴を形成することになり、チューブ本体に貫通孔が発生するおそれが生じる。
Furthermore, the pure Si powder contained in the paint forms a fillet when the Al-Si alloy liquid phase brazing produced by eutectic melting with the aluminum on the tube surface flows to the contact area between the fin and the tube. . At this time, if coarse Si grains are mixed, the liquid phase brazing eutectic melted with the aluminum on the surface of the coarse Si grains and the tube surface quickly flows to the contact portion between the fin and the tube due to capillary action. The surroundings of the Si grains that have become smaller are separated from the tube surface, forming depressions on the tube surface where the liquid phase brazing flows out, and further eutectic melting progresses at the bottom of the depressions that are in contact with the Si grains. If so, a deep melted hole is formed, and there is a possibility that a through hole is generated in the tube body.
特許文献1では、それ以下の粒径を有する粒子の累積体積が全粒子の99%となる粒径(99%粒径、D99)の5倍以上となる粗大粒の含有量が1ppm未満であるSi粉末を用いて、上記課題を解決しようとしているが、粗大粒子の混入を1ppm未満にするための課題も生じていた。
In Patent Document 1, the content of coarse grains that is five times or more the grain size (99% grain size, D99) at which the cumulative volume of grains having a grain size below that is 99% of all grains is less than 1 ppm. An attempt has been made to solve the above problem by using Si powder, but there has also been a problem of reducing the contamination of coarse particles to less than 1 ppm.
特許文献2の手法においては、ろう材粉末のうちSiを含む合金としてAl-Si合金粉末が例に挙げられている。塗装チューブにろう材としてAl-Si合金粉末を用いた場合、純Si粉末の場合と異なりチューブ表面にエロージョンを生じ、ろう付中に減肉する懸念がある。さらに、フラックスとしてZn含有フラックスが用いられている。前述したフラックスの反応により液相の生成直前にチューブ外表面でZnが析出する反応が進行していることから、生成した液相には高濃度のZnが含まれることとなる。このZnはチューブ外表面に拡散してZn拡散層を形成し、犠牲防食層として機能することでチューブにおける孔食の発生を抑制するが、Zn量が多く、チューブ表面とチューブ深部の電位差が大きい場合は腐食速度が大きくなり、チューブの減肉速度が速くなってしまう。また、ろう付中の液相に含まれたZnは、フィンとチューブの間に形成されるフィレット中にも濃縮する。この場合、フィレットの電位が最も卑になることで、腐食環境にさらされた際にフィレットが優先的に腐食して消耗し、フィンの脱落を生じ、早期に熱交換性能が低下するとともに、フィンによりチューブが防食されなくなることでチューブに早期貫通が生じ得ることを意味する。本技術ではそれらの対策が記載されておらず、実用的であるとは言い難いものである。
In the method of Patent Document 2, an Al-Si alloy powder is cited as an example of an alloy containing Si among brazing powders. When Al--Si alloy powder is used as a brazing material for a coated tube, erosion occurs on the tube surface unlike the case of pure Si powder, and there is a concern that the tube may be thinned during brazing. Furthermore, a Zn-containing flux is used as the flux. Since the above-described flux reaction causes Zn to precipitate on the outer surface of the tube immediately before the liquid phase is generated, the generated liquid phase contains Zn at a high concentration. This Zn diffuses to the outer surface of the tube to form a Zn diffusion layer, which functions as a sacrificial anticorrosive layer to suppress the occurrence of pitting corrosion in the tube. In this case, the corrosion rate increases, and the thinning rate of the tube increases. Zn contained in the liquid phase during brazing also concentrates in the fillets formed between the fins and tubes. In this case, since the potential of the fillet becomes the most base, the fillet is preferentially corroded and worn when exposed to a corrosive environment, causing the fins to come off, resulting in early deterioration of the heat exchange performance and the fins. This means that premature penetration of the tube may occur due to the tube not being protected against corrosion. The present technology does not describe such countermeasures, and it is difficult to say that it is practical.
また、熱交換器のチューブに従来よく使用されるZn溶射チューブにおいては、表面Zn量は通常は5~15g/m2であり、チューブ表面とチューブ深部の電位差を小さくし、腐食速度を小さくするため、また、フィレットへのZn濃縮を低減するためにZn量を5g/m2以下とした場合には、チューブ表面へ均一にZnを溶射することが困難であった。
In addition, in Zn sprayed tubes, which are conventionally often used for heat exchanger tubes, the amount of surface Zn is usually 5 to 15 g/m 2 , which reduces the potential difference between the tube surface and the tube depth and reduces the corrosion rate. Therefore, when the amount of Zn is set to 5 g/m 2 or less in order to reduce the concentration of Zn on the fillet, it is difficult to spray Zn uniformly onto the tube surface.
従って、本発明の目的は、ろう付けの際にチューブ肉厚を減少させることなく又は肉厚の減少量が非常に少なくフィンとチューブが接合され、ろう付性が良好であり、且つ、長期間に亘ってフィンが脱落し難く、優れた耐食性を有する、自動車用熱交換器に用いられるアルミニウム合金製の押出チューブ及び該押出チューブが用いられている熱交換器を提供することにある。
Therefore, the object of the present invention is to join the fins and the tube without reducing the thickness of the tube during brazing or with a very small amount of reduction in thickness, and to have good brazeability and a long-term use. To provide an extruded tube made of an aluminum alloy used in a heat exchanger for an automobile, and having excellent corrosion resistance, and a heat exchanger using the extruded tube.
本発明者らは、上記課題を解決するために鋭意検討を重ねた結果、チューブ本体と、チューブ表面に塗布された塗膜とを有するアルミニウム合金押出チューブにおいて、チューブの外表面に、Al-Si合金からなるろう材粉末と、Zn含有フッ化物系フラックス粉末と、Zn非含有フッ化物系フラックス粉末とを、特定の塗布量で塗布することにより、ろう付中にチューブ表面が溶融されない又は溶融され難いため、ろう付中にチューブ肉厚が減少されず又は非常に減少量が少なく、ろう付中にチューブ外表面にZn拡散層が形成されるため、チューブ表層の犠牲防食層とフィンにより防食されることで耐食性に優れることを見出し、本発明を完成させた。
The present inventors have made intensive studies to solve the above problems, and as a result, in an aluminum alloy extruded tube having a tube body and a coating film applied to the tube surface, Al-Si is added to the outer surface of the tube. By applying specific coating amounts of the alloy brazing powder, the Zn-containing fluoride-based flux powder, and the Zn-free fluoride-based flux powder, the tube surface is not melted or melted during brazing. Therefore, the thickness of the tube is not reduced during brazing, or the amount of reduction is very small, and a Zn diffusion layer is formed on the outer surface of the tube during brazing, so corrosion is prevented by the sacrificial anticorrosive layer and fins on the tube surface layer. The present inventors have completed the present invention by discovering that the corrosion resistance is excellent.
上記本発明の課題は、以下の本発明によって解決される。
すなわち、本発明(1)は、自動車用熱交換器に用いられるアルミニウム合金製の押出チューブであり、
Mnを含有するアルミニウム合金からなるチューブ本体と、
該チューブ本体の表面に形成されている塗膜と、
を有し、
該塗膜は、Al-Si合金ろう材粉末と、Zn含有フッ化物系フラックス粉末と、Zn非含有フッ化物系フラックス粉末と、バインダと、を含有しており、
該Al-Si合金ろう材粉末の塗布量が9.0~25.0g/m2であり、該Zn含有フッ化物系フラックス粉末の塗布量が1.0~9.0g/m2であり、該Zn非含有フッ化物系フラックス粉末の塗布量が1.0~11.0g/m2であり、該バインダの塗布量が1.0~13.0g/m2であること、
を特徴とする熱交換器用アルミニウム合金押出チューブを提供するものである。 The above problems of the present invention are solved by the following present invention.
That is, the present invention (1) is an aluminum alloy extruded tube used in a heat exchanger for automobiles,
a tube body made of an aluminum alloy containing Mn;
a coating film formed on the surface of the tube body;
has
The coating contains Al—Si alloy brazing powder, Zn-containing fluoride-based flux powder, Zn-free fluoride-based flux powder, and a binder,
The coating amount of the Al—Si alloy brazing filler metal powder is 9.0 to 25.0 g/m 2 , the coating amount of the Zn-containing fluoride flux powder is 1.0 to 9.0 g/m 2 , The coating amount of the Zn-free fluoride-based flux powder is 1.0 to 11.0 g/m 2 and the coating amount of the binder is 1.0 to 13.0 g/m 2 ;
To provide an aluminum alloy extruded tube for a heat exchanger characterized by:
すなわち、本発明(1)は、自動車用熱交換器に用いられるアルミニウム合金製の押出チューブであり、
Mnを含有するアルミニウム合金からなるチューブ本体と、
該チューブ本体の表面に形成されている塗膜と、
を有し、
該塗膜は、Al-Si合金ろう材粉末と、Zn含有フッ化物系フラックス粉末と、Zn非含有フッ化物系フラックス粉末と、バインダと、を含有しており、
該Al-Si合金ろう材粉末の塗布量が9.0~25.0g/m2であり、該Zn含有フッ化物系フラックス粉末の塗布量が1.0~9.0g/m2であり、該Zn非含有フッ化物系フラックス粉末の塗布量が1.0~11.0g/m2であり、該バインダの塗布量が1.0~13.0g/m2であること、
を特徴とする熱交換器用アルミニウム合金押出チューブを提供するものである。 The above problems of the present invention are solved by the following present invention.
That is, the present invention (1) is an aluminum alloy extruded tube used in a heat exchanger for automobiles,
a tube body made of an aluminum alloy containing Mn;
a coating film formed on the surface of the tube body;
has
The coating contains Al—Si alloy brazing powder, Zn-containing fluoride-based flux powder, Zn-free fluoride-based flux powder, and a binder,
The coating amount of the Al—Si alloy brazing filler metal powder is 9.0 to 25.0 g/m 2 , the coating amount of the Zn-containing fluoride flux powder is 1.0 to 9.0 g/m 2 , The coating amount of the Zn-free fluoride-based flux powder is 1.0 to 11.0 g/m 2 and the coating amount of the binder is 1.0 to 13.0 g/m 2 ;
To provide an aluminum alloy extruded tube for a heat exchanger characterized by:
本発明(2)は、前記アルミニウム合金が、0.20~1.20質量%のMnと、0.10質量%以下のTiと、を含有し、残部Al及び不可避不純物からなることを特徴とする(1)の熱交換器用アルミニウム合金押出チューブを提供するものである。
The present invention (2) is characterized in that the aluminum alloy contains 0.20 to 1.20% by mass of Mn and 0.10% by mass or less of Ti, and the balance is Al and unavoidable impurities. The present invention provides an aluminum alloy extruded tube for a heat exchanger according to (1).
本発明(3)は、Znを含有するアルミニウム合金からなるフィンにろう付により接合したとき、自然電位測定において、前記押出チューブのチューブ表面とチューブ深部との電位差(チューブ表面の電位-チューブ深部の電位)が、-180~-40mVとなることを特徴とする(1)又は(2)の熱交換器用アルミニウム合金押出チューブを提供するものである。
In the present invention (3), when a fin made of an aluminum alloy containing Zn is joined by brazing, in spontaneous potential measurement, the potential difference between the tube surface and the tube depth of the extruded tube (tube surface potential - tube depth potential) of -180 to -40 mV.
本発明(4)は、600℃±10℃で3分間保持し、室温まで冷却した後の平均結晶粒径を測定する加熱試験において、加熱試験後の前記チューブ本体の平均結晶粒径が150μm以上であることを特徴とする(1)~(3)のいずれか1の熱交換器用アルミニウム合金押出チューブを提供するものである。
In the present invention (4), the average crystal grain size of the tube body after the heating test is held at 600° C.±10° C. for 3 minutes and cooled to room temperature to measure the average crystal grain size of 150 μm or more. An aluminum alloy extruded tube for a heat exchanger according to any one of (1) to (3) is provided.
本発明(5)は、(1)~(4)のいずれか1の熱交換器用アルミニウム合金押出チューブと、Znを含有するアルミニウム合金からなるフィンとがろう付により接合されていることを特徴とする熱交換器を提供するものである。
The present invention (5) is characterized in that the heat exchanger aluminum alloy extruded tube according to any one of (1) to (4) and a fin made of an aluminum alloy containing Zn are joined by brazing. The present invention provides a heat exchanger that
本発明(6)は、Mnを含有するアルミニウム合金からなるアルミニウム合金押出チューブと、該アルミニウム押出チューブにろう付接合されており、Znを含有するアルミニウム合金からなるフィンと、を有し、
該アルミニウム合金押出チューブは、チューブ表面にZn拡散層を有し、
自然電位測定において、該アルミニウム合金押出チューブのチューブ表面とチューブ深部との電位差(チューブ表面の電位-チューブ深部の電位)が、-180~-40mVであること、
を特徴とする熱交換器を提供するものである。 The present invention (6) comprises an aluminum alloy extruded tube made of an aluminum alloy containing Mn, and a fin brazed to the aluminum extruded tube and made of an aluminum alloy containing Zn,
The aluminum alloy extruded tube has a Zn diffusion layer on the tube surface,
In spontaneous potential measurement, the potential difference between the tube surface and the tube depth of the aluminum alloy extruded tube (tube surface potential - tube depth potential) is -180 to -40 mV,
To provide a heat exchanger characterized by
該アルミニウム合金押出チューブは、チューブ表面にZn拡散層を有し、
自然電位測定において、該アルミニウム合金押出チューブのチューブ表面とチューブ深部との電位差(チューブ表面の電位-チューブ深部の電位)が、-180~-40mVであること、
を特徴とする熱交換器を提供するものである。 The present invention (6) comprises an aluminum alloy extruded tube made of an aluminum alloy containing Mn, and a fin brazed to the aluminum extruded tube and made of an aluminum alloy containing Zn,
The aluminum alloy extruded tube has a Zn diffusion layer on the tube surface,
In spontaneous potential measurement, the potential difference between the tube surface and the tube depth of the aluminum alloy extruded tube (tube surface potential - tube depth potential) is -180 to -40 mV,
To provide a heat exchanger characterized by
本発明によれば、ろう付けの際にチューブ肉厚を減少させることなく又は肉厚の減少量が非常に少なくフィンとチューブが接合され、ろう付性が良好であり、且つ、長期間に亘ってフィンが脱落し難く、ろう付によりチューブ表層に犠牲防食層としてのZn拡散層が形成され、チューブ表層の犠牲防食層とフィンにより防食されることで優れた耐食性を有する、自動車用熱交換器に用いられるアルミニウム合金製の押出チューブ及び該押出チューブが用いられている熱交換器を提供することができる。
According to the present invention, the fins and the tube are joined without reducing the thickness of the tube during brazing or with a very small amount of reduction in thickness, and the brazeability is good, and it can be used for a long time. The fins are difficult to fall off, and the Zn diffusion layer as a sacrificial corrosion protection layer is formed on the tube surface layer by brazing, and corrosion is prevented by the sacrificial corrosion protection layer on the tube surface layer and the fins, resulting in excellent corrosion resistance. It is possible to provide an aluminum alloy extruded tube used for and a heat exchanger using the extruded tube.
本発明のアルミニウム合金押出チューブは、自動車用熱交換器に用いられるアルミニウム合金製の押出チューブであり、
Mnを含有するアルミニウム合金からなるチューブ本体と、
該チューブ本体の表面に形成されている塗膜と、
を有し、
該塗膜は、Al-Si合金ろう材粉末と、Zn含有フッ化物系フラックス粉末と、Zn非含有フッ化物系フラックス粉末と、バインダと、を含有しており、
該Al-Si合金ろう材粉末の塗布量が9.0~25.0g/m2であり、該Zn含有フッ化物系フラックス粉末の塗布量が1.0~9.0g/m2であり、該Zn非含有フッ化物系フラックス粉末の塗布量が1.0~11.0g/m2であり、該バインダの塗布量が1.0~13.0g/m2であること、
を特徴とする熱交換器用アルミニウム合金押出チューブである。 The aluminum alloy extruded tube of the present invention is an aluminum alloy extruded tube used in a heat exchanger for automobiles,
a tube body made of an aluminum alloy containing Mn;
a coating film formed on the surface of the tube body;
has
The coating contains Al—Si alloy brazing powder, Zn-containing fluoride-based flux powder, Zn-free fluoride-based flux powder, and a binder,
The coating amount of the Al—Si alloy brazing filler metal powder is 9.0 to 25.0 g/m 2 , the coating amount of the Zn-containing fluoride flux powder is 1.0 to 9.0 g/m 2 , The coating amount of the Zn-free fluoride-based flux powder is 1.0 to 11.0 g/m 2 and the coating amount of the binder is 1.0 to 13.0 g/m 2 ;
An aluminum alloy extruded tube for a heat exchanger characterized by
Mnを含有するアルミニウム合金からなるチューブ本体と、
該チューブ本体の表面に形成されている塗膜と、
を有し、
該塗膜は、Al-Si合金ろう材粉末と、Zn含有フッ化物系フラックス粉末と、Zn非含有フッ化物系フラックス粉末と、バインダと、を含有しており、
該Al-Si合金ろう材粉末の塗布量が9.0~25.0g/m2であり、該Zn含有フッ化物系フラックス粉末の塗布量が1.0~9.0g/m2であり、該Zn非含有フッ化物系フラックス粉末の塗布量が1.0~11.0g/m2であり、該バインダの塗布量が1.0~13.0g/m2であること、
を特徴とする熱交換器用アルミニウム合金押出チューブである。 The aluminum alloy extruded tube of the present invention is an aluminum alloy extruded tube used in a heat exchanger for automobiles,
a tube body made of an aluminum alloy containing Mn;
a coating film formed on the surface of the tube body;
has
The coating contains Al—Si alloy brazing powder, Zn-containing fluoride-based flux powder, Zn-free fluoride-based flux powder, and a binder,
The coating amount of the Al—Si alloy brazing filler metal powder is 9.0 to 25.0 g/m 2 , the coating amount of the Zn-containing fluoride flux powder is 1.0 to 9.0 g/m 2 , The coating amount of the Zn-free fluoride-based flux powder is 1.0 to 11.0 g/m 2 and the coating amount of the binder is 1.0 to 13.0 g/m 2 ;
An aluminum alloy extruded tube for a heat exchanger characterized by
本発明の熱交換器用押出チューブは、アルミニウム合金により形成されており、アルミニウム合金を押出成形することにより作製されたアルミニウム合金製のチューブである。そして、本発明のアルミニウム合金押出チューブは、フィン等とろう付されることにより、自動車用熱交換器において、冷媒が流通するチューブに用いられる。
The extruded tube for a heat exchanger of the present invention is made of an aluminum alloy, and is an aluminum alloy tube produced by extruding an aluminum alloy. The aluminum alloy extruded tube of the present invention is brazed with fins or the like to be used as a tube through which a refrigerant flows in a heat exchanger for automobiles.
(チューブ)
本発明のアルミニウム合金押出チューブに係るチューブ本体は、Mnを含有するアルミニウム合金により形成されている。Mnは、アルミニウム母相中に固溶することにより、強度を向上させる作用を有し、また、電位を貴にする効果も有する。 (tube)
The tube body according to the aluminum alloy extruded tube of the present invention is made of an aluminum alloy containing Mn. Mn has the effect of improving the strength by forming a solid solution in the aluminum matrix, and also has the effect of making the potential noble.
本発明のアルミニウム合金押出チューブに係るチューブ本体は、Mnを含有するアルミニウム合金により形成されている。Mnは、アルミニウム母相中に固溶することにより、強度を向上させる作用を有し、また、電位を貴にする効果も有する。 (tube)
The tube body according to the aluminum alloy extruded tube of the present invention is made of an aluminum alloy containing Mn. Mn has the effect of improving the strength by forming a solid solution in the aluminum matrix, and also has the effect of making the potential noble.
チューブ本体を形成するMnを含有するアルミニウム合金は、0.20~1.20質量%のMnを含有し、Ti含有量が0.10質量%以下であり、残部がAl及び不可避不純物からなることが好ましい。
The Mn-containing aluminum alloy that forms the tube body contains 0.20 to 1.20% by mass of Mn, has a Ti content of 0.10% by mass or less, and the balance is Al and inevitable impurities. is preferred.
チューブ本体を形成するMnを含有するアルミニウム合金中、Mn含有量は、好ましくは0.20~1.20質量%、特に好ましくは0.40~1.20質量%である。Mnを含有するアルミニウム合金中のMn含有量が上記範囲にあることにより、十分な強度向上効果及びチューブ深部における電位貴化効果を得ることができる。一方、アルミニウム合金中のMn含有量が、上記範囲未満だと、上記効果が得られ難く、また、上記範囲を超えると、後述する熱間加工以前の工程で母相中にAl-Mn析出物を生じ、これが粒界の移動を抑制することで、ろう付後の結晶組織が微細となり、ろう付不具合を生じ得、また、更に、押出加工における加工性が低くなり、チューブ本体の生産性が低くなるおそれがある。
In the Mn-containing aluminum alloy forming the tube body, the Mn content is preferably 0.20 to 1.20% by mass, particularly preferably 0.40 to 1.20% by mass. When the Mn content in the Mn-containing aluminum alloy is within the above range, it is possible to obtain a sufficient strength improvement effect and potential noble effect in the deep portion of the tube. On the other hand, if the Mn content in the aluminum alloy is less than the above range, it is difficult to obtain the above effects. By suppressing the movement of grain boundaries, the crystal structure after brazing becomes fine, which may cause brazing defects, and furthermore, the workability in extrusion processing is lowered, and the productivity of the tube body is reduced. is likely to be lower.
チューブ本体を形成するMnを含有するアルミニウム合金中、Ti含有量は、好ましくは0.10質量%以下、より好ましくは0.001~0.08質量%である。Mnを含有するアルミニウム合金中のTi含有量が、上記範囲にあることにより、鋳造時の組織を微細にすることができる。一方、アルミニウム合金中のTi含有量が、上記範囲を超えると、鋳造時に巨大結晶物が生成し、健全なチューブ本体の製造が困難となるおそれがあり、また、押出多穴管の場合には、晶出したTiがダイスとの間に摩擦を生じさせ、生産性や工具寿命を低下させるおそれがある。
The Ti content in the Mn-containing aluminum alloy forming the tube body is preferably 0.10% by mass or less, more preferably 0.001 to 0.08% by mass. When the Ti content in the Mn-containing aluminum alloy is within the above range, the structure can be refined during casting. On the other hand, if the Ti content in the aluminum alloy exceeds the above range, large crystals may form during casting, making it difficult to produce a healthy tube body. , the crystallized Ti may cause friction with the die, which may reduce productivity and tool life.
チューブ本体としては、上記のMnを含有するアルミニウム合金の化学成分に調整され鋳造されたアルミニウム合金鋳塊、すなわち、0.20~1.20質量%、好ましくは0.40~1.20質量%のMnを含有し、Ti含有量が0.10質量%以下、好ましくは0.001~0.08質量%であり、残部Al及び不可避不純物からなるアルミニウム合金の鋳塊に、以下の均質化処理が施されたアルミニウム合金を用いて、熱間押出加工されたものであることが好ましい。
均質化処理としては、以下の第一の形態の均質化処理及び第二の形態の均質化処理が挙げられる。 As the tube main body, an aluminum alloy ingot adjusted to the chemical composition of the aluminum alloy containing Mn and cast, that is, 0.20 to 1.20% by mass, preferably 0.40 to 1.20% by mass of Mn, Ti content is 0.10% by mass or less, preferably 0.001 to 0.08% by mass, and the balance is Al and inevitable impurities An aluminum alloy ingot is subjected to the following homogenization treatment It is preferably an aluminum alloy subjected to hot extrusion.
The homogenization treatment includes the following first form of homogenization treatment and second form of homogenization treatment.
均質化処理としては、以下の第一の形態の均質化処理及び第二の形態の均質化処理が挙げられる。 As the tube main body, an aluminum alloy ingot adjusted to the chemical composition of the aluminum alloy containing Mn and cast, that is, 0.20 to 1.20% by mass, preferably 0.40 to 1.20% by mass of Mn, Ti content is 0.10% by mass or less, preferably 0.001 to 0.08% by mass, and the balance is Al and inevitable impurities An aluminum alloy ingot is subjected to the following homogenization treatment It is preferably an aluminum alloy subjected to hot extrusion.
The homogenization treatment includes the following first form of homogenization treatment and second form of homogenization treatment.
第一の形態の均質化処理では、所定の化学組成を有するアルミニウム合金鋳塊を、400~650℃で2時間以上保持する。第一の形態の均質化処理における処理温度は、400~650℃、好ましくは430~620℃である。均質化処理の処理温度が、上記範囲にあることにより、鋳造時に形成される粗大な晶出物を分解あるいは粒状化させ、鋳造時に生じた偏析層などの不均一な組織を均一化させることができる。その結果、押出加工時の抵抗を低減して押出性を向上させることができ、また、押出後の製品の表面粗度を小さくすることができる。一方、均質化処理の処理温度が、上記範囲未満だと、粗大な晶出物や上記の不均一な組織が残存するおそれがあり、押出製の低下や表面粗度の増大を招くおそれがあり、また、上記範囲を超えると、鋳塊の溶融を招くおそれがある。均質化処理の処理時間は、2時間以上、好ましくは5時間以上である。均質化処理の処理時間が、上記範囲であることにより、均質化が十分となる。また、均質化処理の処理時間は、24時間を超えても、均質化の効果が飽和するため、24時間以下が好ましい。
In the first form of homogenization treatment, an aluminum alloy ingot having a predetermined chemical composition is held at 400-650°C for 2 hours or longer. The treatment temperature in the first form of homogenization treatment is 400-650°C, preferably 430-620°C. When the treatment temperature of the homogenization treatment is within the above range, coarse crystallized substances formed during casting can be decomposed or granulated, and uneven structures such as segregation layers generated during casting can be homogenized. can. As a result, resistance during extrusion can be reduced to improve extrudability, and the surface roughness of the product after extrusion can be reduced. On the other hand, if the treatment temperature of the homogenization treatment is less than the above range, there is a risk that coarse crystallized substances and the uneven structure described above will remain, which may lead to deterioration in extrusion performance and increase in surface roughness. Moreover, if the above range is exceeded, there is a risk of inducing melting of the ingot. The treatment time for the homogenization treatment is 2 hours or more, preferably 5 hours or more. Homogenization becomes sufficient when the treatment time of the homogenization treatment is within the above range. Moreover, even if the treatment time of the homogenization treatment exceeds 24 hours, the effect of homogenization is saturated, so 24 hours or less is preferable.
第二の形態の均質化処理では、所定の化学組成を有するアルミニウム合金鋳塊を、550~650℃で2時間以上保持する第一均質化処理を行い、第一均質化処理を行った後、アルミニウム合金鋳塊を、400~550℃で3時間以上保持する第二均質化処理を行う。
In the second form of homogenization treatment, an aluminum alloy ingot having a predetermined chemical composition is subjected to a first homogenization treatment of holding at 550 to 650 ° C. for 2 hours or more, and after performing the first homogenization treatment, A second homogenization treatment is performed by holding the aluminum alloy ingot at 400 to 550° C. for 3 hours or longer.
第二の形態の均質化処理に係る第一均質化処理における処理温度は、550~650℃、好ましくは580~620℃である。第一均質化処理の処理温度が、上記範囲にあることにより、鋳造時に形成される粗大な晶出物を分解あるいは粒状化させ、また、積極的に再固溶させることができる。一方、第一均質化処理の処理温度が、上記範囲未満だと、再固溶が進み難くなり、また、上記範囲を超えると、鋳塊の溶融を招くおそれがある。第一均質化処理の処理時間は、2時間以上、好ましくは5時間以上である。均質化処理の処理時間が、上記範囲であることにより、上記効果が十分となる。また、均質化処理の処理時間は、24時間を超えても、均質化の効果が飽和するため、24時間以下が好ましい。
The treatment temperature in the first homogenization treatment of the second form of homogenization treatment is 550-650°C, preferably 580-620°C. When the treatment temperature of the first homogenization treatment is within the above range, coarse crystallized substances formed during casting can be decomposed or granulated, and can be positively redissolved. On the other hand, if the treatment temperature of the first homogenization treatment is less than the above range, re-dissolution will be difficult to progress, and if it exceeds the above range, the ingot may melt. The treatment time of the first homogenization treatment is 2 hours or more, preferably 5 hours or more. When the treatment time of the homogenization treatment is within the above range, the above effects are sufficient. Moreover, even if the treatment time of the homogenization treatment exceeds 24 hours, the effect of homogenization is saturated, so 24 hours or less is preferable.
第二の形態の均質化処理に係る第二均質化処理における処理温度は、400~550℃である。第二均質化処理の処理温度が、上記範囲にあることにより、母相中に固溶しているMnを析出させ、Mnの固溶度を低下させることができる。その結果、押出加工における変形抵抗を低下させ、押出性を向上させることができる。一方、第二均質化処理の処理温度が、上記範囲未満だと、Mnの析出量が少なくなるため、変形抵抗を低下させる効果が不十分となるおそれがあり、また、上記範囲を超えると、Mnが析出し難くなるため、変形抵抗を増加させるおそれがある。第二均質化処理の処理時間は、3時間以上、好ましくは5時間以上である。第二均質化処理の処理時間が、上記範囲未満だと、Mnの析出が十分となり、変形抵抗を低下させる効果が不十分となるおそれがある。また、均質化処理の処理時間は、長い方が反応が進むため効果があるが、長すぎても効果が飽和するため、24時間以下が好ましく、15時間以下が特に好ましい。
The treatment temperature in the second homogenization treatment according to the second form of homogenization treatment is 400 to 550°C. When the treatment temperature of the second homogenization treatment is within the above range, Mn dissolved in the matrix phase can be precipitated and the solid solubility of Mn can be reduced. As a result, deformation resistance in extrusion processing can be reduced, and extrudability can be improved. On the other hand, if the treatment temperature of the second homogenization treatment is less than the above range, the amount of precipitation of Mn is reduced, so the effect of reducing deformation resistance may be insufficient. Since it becomes difficult for Mn to precipitate, there is a risk of increasing the deformation resistance. The treatment time of the second homogenization treatment is 3 hours or more, preferably 5 hours or more. If the treatment time of the second homogenization treatment is less than the above range, the precipitation of Mn may be sufficient, and the effect of lowering the deformation resistance may be insufficient. The longer the homogenization treatment time is, the more effective the reaction progresses. However, even if the treatment time is too long, the effect is saturated.
第二の形態の均質化処理において、第一均質化処理と第二均質化処理とを、連続して行ってもよいし、あるいは、第一均質化処理を行った後、一旦、鋳塊を冷却してから、第二均質化処理を行ってもよい。なお、第一均質化処理と第二均質化処理とを連続して行うとは、第一均質化処理が完了した後に、鋳塊の温度を、第二均質化処理の処理温度よりも低い温度に冷却することなく、第二均質化処理の処理温度に達したときに、第二均質化処理を開始するという意味である。また、第一均質化処理を行った後、一旦、鋳塊を冷却してから、第二均質化処理を行う場合には、例えば、第一均質化処理を行った後、鋳塊を200℃以下まで冷却した後に再加熱し、第二均質化処理を行う。
In the second form of homogenization treatment, the first homogenization treatment and the second homogenization treatment may be performed continuously, or after performing the first homogenization treatment, the ingot is once After cooling, a second homogenization treatment may be performed. Note that performing the first homogenization treatment and the second homogenization treatment continuously means that after the first homogenization treatment is completed, the temperature of the ingot is set to a temperature lower than the treatment temperature of the second homogenization treatment It means that the second homogenization treatment is started when the treatment temperature of the second homogenization treatment is reached without cooling to . Further, after performing the first homogenization treatment, once the ingot is cooled and then the second homogenization treatment is performed, for example, after performing the first homogenization treatment, the ingot is heated to 200 ° C. After cooling to below, it is reheated and the second homogenization treatment is performed.
上記第一の形態の均質化処理又は第二の形態の均質化処理が施されたアルミニウム合金鋳塊を、熱間押出加工する方法は、特に制限されない。熱間押出加工の加工温度は、例えば、400~550℃である。
The method of hot-extrusion processing the aluminum alloy ingot that has been subjected to the first form of homogenization treatment or the second form of homogenization treatment is not particularly limited. The processing temperature for hot extrusion processing is, for example, 400 to 550°C.
チューブ本体の形態は、特に制限されず、用途や要求される特性に応じて、適宜選択される。チューブ本体としては、例えば、押出加工により形成され、内部に複数の冷媒流路を有し、押出方向に垂直な断面の形状が扁平な形状である押出扁平多穴管が挙げられる。また、チューブ本体は、例えば、単純な筒状等の形状であってもよい。筒状のチューブは、押出加工により製造されたものであってもよい。
The shape of the tube body is not particularly limited, and is appropriately selected according to the application and required properties. Examples of the tube main body include an extruded flat multi-hole tube formed by extrusion, having a plurality of coolant channels inside, and having a flat cross-sectional shape perpendicular to the extrusion direction. Further, the tube main body may have a shape such as a simple cylindrical shape, for example. The tubular tube may be manufactured by extrusion.
(塗膜)
本発明のアルミニウム合金押出チューブに係る塗膜は、チューブの外表面に形成されている。塗膜は、Al-Si合金ろう材粉末と、Zn含有フッ化物系フラックス粉末と、Zn非含有フッ化物系フラックス粉末と、バインダとを含有している。 (Coating film)
The coating film according to the aluminum alloy extruded tube of the present invention is formed on the outer surface of the tube. The coating contains Al—Si alloy brazing powder, Zn-containing fluoride-based flux powder, Zn-free fluoride-based flux powder, and a binder.
本発明のアルミニウム合金押出チューブに係る塗膜は、チューブの外表面に形成されている。塗膜は、Al-Si合金ろう材粉末と、Zn含有フッ化物系フラックス粉末と、Zn非含有フッ化物系フラックス粉末と、バインダとを含有している。 (Coating film)
The coating film according to the aluminum alloy extruded tube of the present invention is formed on the outer surface of the tube. The coating contains Al—Si alloy brazing powder, Zn-containing fluoride-based flux powder, Zn-free fluoride-based flux powder, and a binder.
Al-Si合金ろう材粉末は、粉末状のAlとSiの合金である。Al-Si合金ろう材粉末は、ろう付時の加熱により、Al-Si合金ろう材粉末自身のみで溶融し、チューブ外表面に液相ろうを生じる。このことにより、チューブをフィンやヘッダと接合させることができる。Al-Si合金ろう材粉末は、Alを含有しているので、ろう付時のろう材によるチューブ外表面の溶融が起こり難い。
The Al-Si alloy brazing powder is an alloy of powdered Al and Si. The Al--Si alloy brazing material powder melts by itself when heated during brazing, and produces liquid-phase brazing on the outer surface of the tube. This allows the tube to be joined to the fins and headers. Since the Al—Si alloy brazing filler metal powder contains Al, the outer surface of the tube is less likely to be melted by the brazing filler metal during brazing.
Al-Si合金ろう材粉末を構成するAlとSiの合金中、Siの含有量は、好ましくは5.0~20.0質量%、特に好ましくは7.0~15.0質量%である。AlとSiの合金中のSiの含有量が上記範囲にあることにより、ろう付時にチューブ外表面の溶融によるチューブ肉厚の減少が起こり難くなると共に、ろう付性が良好になる。
The content of Si in the Al-Si alloy constituting the Al-Si alloy brazing powder is preferably 5.0 to 20.0% by mass, particularly preferably 7.0 to 15.0% by mass. When the content of Si in the alloy of Al and Si is within the above range, it is difficult for the outer surface of the tube to melt during brazing to reduce the thickness of the tube, and the brazeability is improved.
Al-Si合金ろう材粉末の塗布量は、9.0~25.0g/m2、好ましくは12.0~20.0g/m2である。Al-Si合金ろう材粉末の塗布量が上記範囲にあることにより、ろう付性が良好になる。一方、Al-Si合金ろう材粉末の塗布量が、上記範囲未満だと、液相ろうの量が不十分となり、接合不良を生じ易くなり、また、上記範囲を超えると、塗膜厚さが過度に厚くなり、ろう付後のコアの寸法変化が生じ、ろう付性が低くなり易くなる。
The coating amount of the Al—Si alloy brazing powder is 9.0 to 25.0 g/m 2 , preferably 12.0 to 20.0 g/m 2 . When the amount of the Al—Si alloy brazing filler metal powder applied is within the above range, good brazeability is obtained. On the other hand, if the coating amount of the Al—Si alloy brazing material powder is less than the above range, the amount of the liquid phase brazing filler metal will be insufficient, and joint failure will easily occur. It becomes excessively thick, causing dimensional changes in the core after brazing, and the brazeability tends to be low.
Zn含有フッ化物系フラックスは、ろう付加熱中にチューブのAlとの反応によりZnを生成し、チューブ表面にZnの拡散層を形成する。Zn含有フラックスからZnが生成する際に、同時にZn非含有フッ化物系フラックスが生成する。当該Zn非含有フッ化物系フラックスはろう付加熱中に溶融して、Al-Si合金粉末やチューブ外表面の酸化皮膜を先んじて破壊し、液相ろう生成後にただちにろう付が進行することを可能とする。なお、本発明において、「Zn含有」、「Znを含有する」とは、電子線マイクロアナライザによる分析において、Zn量が検出されること(検出下限値以上であること)を指す。
Zn-containing fluoride-based flux generates Zn by reacting with Al in the tube during brazing heat, forming a Zn diffusion layer on the tube surface. When Zn is produced from Zn-containing flux, Zn-free fluoride flux is produced at the same time. The Zn-free fluoride-based flux melts during the brazing heat and destroys the Al-Si alloy powder and the oxide film on the outer surface of the tube in advance, enabling brazing to proceed immediately after the formation of liquid phase brazing. do. In the present invention, the terms "containing Zn" and "containing Zn" indicate that the amount of Zn is detected (beyond the lower limit of detection) in analysis using an electron probe microanalyzer.
Zn含有フッ化物系フラックス粉末としては、例えば、KZnF3、ZnF2が挙げられる。
Examples of Zn-containing fluoride-based flux powders include KZnF 3 and ZnF 2 .
Zn含有フッ化物系フラックス粉末の塗布量は、1.0~9.0g/m2、好ましくは2.0~8.0g/m2である。Zn含有フッ化物系フラックス粉末の塗布量が上記範囲にあることにより、熱交換器が優れた耐食性を有するものとなる。一方、Zn含有フッ化物系フラックス粉末の塗布量が、上記範囲未満の場合は、ろう付加熱後のチューブ表面とチューブ深部の電位差が小さくなるために、犠牲陽極効果が不十分となり、また、上記範囲を超える場合は、チューブ表面とチューブ深部の電位差が過度に大きくなるために、チューブの減肉速度が速くなり、また、フィレットへのZn濃縮の程度が大きくなり、耐食性が低下する。
The coating amount of the Zn-containing fluoride-based flux powder is 1.0 to 9.0 g/m 2 , preferably 2.0 to 8.0 g/m 2 . When the coating amount of the Zn-containing fluoride-based flux powder is within the above range, the heat exchanger has excellent corrosion resistance. On the other hand, if the coating amount of the Zn-containing fluoride-based flux powder is less than the above range, the potential difference between the surface of the tube after brazing heat and the depth of the tube becomes small, resulting in an insufficient sacrificial anode effect. If the range is exceeded, the potential difference between the tube surface and the tube depth becomes excessively large, which increases the rate of thinning of the tube and increases the degree of Zn concentration in the fillet, resulting in a decrease in corrosion resistance.
Zn非含有フッ化物系フラックス粉末は、ろう付時にフラックスとして機能し、ろう付加熱中に溶融して、Al-Si合金ろう材粉末やチューブ外表面の酸化皮膜を破壊し、液相ろう生成後に、直ちにろう付が進行することを可能にする。Zn非含有フッ化物系フラックス粉末は、粉末状であり且つZnを含有しないフッ化物である。なお、本発明において、「Zn非含有」、「Znを含有しない」とは、電子線マイクロアナライザによる分析において、Zn量が検出下限未満であることを指す。
The Zn-free fluoride-based flux powder functions as a flux during brazing, melts during brazing addition heat, destroys the Al-Si alloy brazing powder and the oxide film on the outer surface of the tube, and after the formation of liquid phase brazing, Allows brazing to proceed immediately. The Zn-free fluoride-based flux powder is powdery fluoride containing no Zn. In the present invention, "no Zn" or "no Zn" means that the amount of Zn is below the detection limit in analysis by an electron probe microanalyzer.
Zn非含有フッ化物系フラックス粉末を構成するZn非含有フッ化物としては、例えば、KAlF4、K2AlF5、K3AlF6等のK-Al-F系化合物が挙げられる。また、これらの他に、Zn非含有フッ化物としては、CaF2、LiF等のフラックスも挙げられる。
Examples of the Zn-free fluoride constituting the Zn-free fluoride flux powder include K--Al--F compounds such as KAlF 4 , K 2 AlF 5 and K 3 AlF 6 . In addition to these, Zn-free fluorides include fluxes such as CaF 2 and LiF.
Zn非含有フッ化物系フラックス粉末の塗布量は、1.0~11.0g/m2であり、好ましくは3.0~11.0g/m2である。Zn非含有フッ化物系フラックス粉末の塗布量が上記範囲にあることにより、ろう付時の酸化皮膜の破壊効果が十分となる。一方、Zn非含有フッ化物系フラックス粉末の塗布量が、上記範囲未満だと、フラックス成分が不足するため、酸化皮膜の破壊が不十分となり、ろう付性が低くなり易く、また、上記範囲を超えると、塗膜厚さが過度に厚くなり、ろう付後のコアの寸法変化が生じ、ろう付性が低くなり易くなる。
The coating amount of the Zn-free fluoride-based flux powder is 1.0 to 11.0 g/m 2 , preferably 3.0 to 11.0 g/m 2 . When the coating amount of the Zn-free fluoride-based flux powder is within the above range, the effect of destroying the oxide film during brazing is sufficient. On the other hand, if the coating amount of the Zn-free fluoride-based flux powder is less than the above range, the flux component will be insufficient, resulting in insufficient destruction of the oxide film, and the brazability will tend to be low. If it exceeds, the coating thickness becomes excessively thick, the dimensional change of the core after brazing occurs, and the brazeability tends to deteriorate.
ろう付性の観点から、Zn含有フッ化物系フラックス粉末の塗布量とZn非含有フッ化物系フラックス粉末の塗布量の合計は3.0~15.0g/m2であることが好ましく、5.0~13.0g/m2であることが特に好ましい。Zn含有フッ化物系フラックス粉末の塗布量とZn非含有フッ化物系フラックス粉末の塗布量の合計が上記範囲であることにより、十分なろう付性が得られる。一方、Zn含有フッ化物系フラックス粉末の塗布量とZn非含有フッ化物系フラックス粉末の塗布量の合計が上記範囲未満だと、フラックス成分が不足するため、酸化皮膜の破壊が不十分となり、ろう付性が低くなり易く、また、上記範囲を超えると、前述の酸化皮膜を破壊する効果が飽和する一方、フラックス溶融後の塗膜厚さの変化が過度に大きくなるため、ろう付中のコアの寸法変化を生じ、ろう付性が低下する懸念がある。
4. From the viewpoint of brazing properties, the total coating amount of the Zn-containing fluoride-based flux powder and the coating amount of the Zn-free fluoride-based flux powder is preferably 3.0 to 15.0 g/m 2 . Particularly preferred is 0 to 13.0 g/m 2 . Sufficient brazability can be obtained by setting the total coating amount of the Zn-containing fluoride-based flux powder and the coating amount of the Zn-free fluoride-based flux powder within the above range. On the other hand, if the total coating amount of the Zn-containing fluoride-based flux powder and the coating amount of the Zn-free fluoride-based flux powder is less than the above range, the flux component will be insufficient, resulting in insufficient destruction of the oxide film and soldering. In addition, if the above range is exceeded, the effect of destroying the oxide film described above is saturated, but the change in the coating thickness after melting the flux becomes excessively large, so the core during brazing dimensional change, and there is a concern that the brazeability may deteriorate.
バインダは、Al-Si合金ろう材粉末、Zn含有フッ化物系フラックス粉末及びZn非含有フッ化物系フラックス粉末を、チューブ本体の表面に付着させるものである。バインダとしては、例えば、アクリル系樹脂、ウレタン系樹脂等が挙げられる。
The binder adheres Al-Si alloy brazing powder, Zn-containing fluoride-based flux powder, and Zn-free fluoride-based flux powder to the surface of the tube body. Examples of binders include acrylic resins and urethane resins.
バインダの塗布量は、1.0~13.0g/m2である。バインダの塗布量が上記範囲にあることにより、Al-Si合金ろう材粉末、Zn含有フッ化物系フラックス粉末及びZn非含有フッ化物系フラックス粉末を、チューブ本体の表面に良好に付着させることができる。一方、バインダの塗布量が、上記範囲未満だと、塗膜の剥離が生じ易くなり、また、上記範囲を超えると、バインダの熱分解が不十分となり、ろう付の際に未分解のバインダ等が残留し、ろう付性が低くなるおそれがある。
The coating amount of the binder is 1.0 to 13.0 g/m 2 . When the coating amount of the binder is within the above range, the Al—Si alloy brazing powder, the Zn-containing fluoride flux powder, and the Zn-free fluoride flux powder can be adhered well to the surface of the tube body. . On the other hand, if the coating amount of the binder is less than the above range, the coating film tends to peel off. may remain and the brazability may deteriorate.
チューブ本体の表面に、塗膜を形成させる方法としては、例えば、Al-Si合金ろう材粉末、Zn含有フッ化物系フラックス粉末、Zn非含有フッ化物系フラックス粉末及びバインダを、溶剤に混合し、得られるペーストをチューブ本体の表面に塗布した後、溶剤を乾燥して除去することにより、塗膜を形成させる方法が挙げられる。Al-Si合金ろう材粉末、Zn含有フッ化物系フラックス粉末及びZn非含有フッ化物系フラックス粉末を、溶剤に混合する前に、予め、Al-Si合金ろう材粉末と、Zn含有フッ化物系フラックス粉末と、Zn非含有フッ化物系フラックス粉末と、を混合して、Al-Si合金ろう材粉末、Zn含有フッ化物系フラックス粉末及びZn非含有フッ化物系フラックス粉末の混合粉末にしてから、得られる混合粉末をバインダと共に、溶剤に混合してもよい。チューブ本体の表面への上記ペーストの塗布には、例えば、ロールコート法等が用いられる。
As a method for forming a coating film on the surface of the tube body, for example, Al—Si alloy brazing powder, Zn-containing fluoride-based flux powder, Zn-free fluoride-based flux powder, and a binder are mixed with a solvent, A coating film can be formed by applying the obtained paste to the surface of the tube body and then drying and removing the solvent. Before mixing the Al—Si alloy brazing filler metal powder, the Zn-containing fluoride flux powder, and the Zn-free fluoride flux powder in the solvent, the Al—Si alloy brazing filler metal powder and the Zn-containing fluoride flux are mixed in advance. Powder and Zn-free fluoride-based flux powder are mixed to form a mixed powder of Al—Si alloy brazing powder, Zn-containing fluoride-based flux powder, and Zn-free fluoride-based flux powder. The mixed powder obtained may be mixed in a solvent together with a binder. For example, a roll coating method or the like is used to apply the paste to the surface of the tube body.
本発明のアルミニウム合金押出チューブは、好ましくは、Znを含有するアルミニウム合金からなるフィンにろう付により接合したとき、自然電位測定において、ろう付接合後のアルミニウム合金押出チューブのチューブ表面とチューブ深部との電位差(チューブ表面の電位-チューブ深部の電位)が、好ましくは-180~-40mV、特に好ましくは-150~-40mVである。本発明のアルミニウム合金押出チューブでは、Zn含有フッ化物系フラックス粉末を含む塗膜によりチューブ表面にZn拡散層が形成されるため、チューブ表面とチューブ深部との間に電位差が形成され、該電位差が上記範囲であることにより、十分な犠牲防食効果を発揮し、チューブ単体として優れた防食性能を有する。なお、本発明において、アルミニウム合金押出チューブのチューブ深部の電位とは、ろう付後のアルミニウム合金押出チューブの表面から150μm以上深いの部分の電位を指す。
Preferably, when the aluminum alloy extruded tube of the present invention is joined to a fin made of an aluminum alloy containing Zn by brazing, in the self-potential measurement, the surface of the aluminum alloy extruded tube after brazing and the tube depth (tube surface potential-tube deep potential) is preferably -180 to -40 mV, particularly preferably -150 to -40 mV. In the aluminum alloy extruded tube of the present invention, a Zn diffusion layer is formed on the tube surface by the coating containing the Zn-containing fluoride-based flux powder, so that a potential difference is formed between the tube surface and the deep part of the tube. By being within the above range, a sufficient sacrificial anti-corrosion effect is exhibited, and the tube itself has excellent anti-corrosion performance. In the present invention, the electric potential at the tube depth of the aluminum alloy extruded tube refers to the electric potential at a depth of 150 μm or more from the surface of the aluminum alloy extruded tube after brazing.
本発明の熱交換器用アルミニウム合金押出チューブは、好ましくは、600℃±10℃で3分間保持し、室温まで冷却した後の平均結晶粒径を測定する加熱試験において、加熱試験後のチューブ本体の平均結晶粒径が150μm以上である。つまり、熱交換器用アルミニウム合金押出チューブは、600℃±10℃で3分間保持し、室温まで冷却することにより、チューブ本体の平均結晶粒径が150μm以上となるような、結晶組織を有している。なお、熱交換器用アルミニウム合金押出チューブを、600℃±10℃で3分間保持し、室温まで冷却した後の平均結晶粒径を測定する加熱試験をしたときのチューブ本体の平均結晶粒径が150μm以上であることにより、ろう付加熱中に、液相ろうが結晶粒界を侵食する所謂エロージョンが発生し難く、チューブ肉厚の減少やチューブの貫通が起こり難くなり、また、ろう量の減少による接合不良が起こり難くなるので、ろう付性が良好になる。
The aluminum alloy extruded tube for a heat exchanger of the present invention is preferably kept at 600 ° C. ± 10 ° C. for 3 minutes, cooled to room temperature, and then cooled to room temperature. The average grain size is 150 μm or more. In other words, the aluminum alloy extruded tube for a heat exchanger has a crystal structure such that the tube body has an average crystal grain size of 150 μm or more when it is held at 600° C.±10° C. for 3 minutes and cooled to room temperature. there is The aluminum alloy extruded tube for a heat exchanger was kept at 600°C ± 10°C for 3 minutes, and after cooling to room temperature, a heating test was conducted to measure the average crystal grain size. Due to the above, during the brazing heat, the so-called erosion in which the liquid phase brazing erodes the crystal grain boundaries is difficult to occur, the decrease in the tube wall thickness and the penetration of the tube are difficult to occur, and the reduction in the amount of brazing Since defects are less likely to occur, brazeability is improved.
熱交換器用アルミニウム合金押出チューブに係る加熱試験は、先ず、熱交換器用アルミニウム合金押出チューブを、加熱して昇温し、昇温過程において、600℃±10℃の保持温度まで加熱し、次いで、600℃±10℃で3分間保持し、次いで、室温まで冷却する加熱試験を行い、次いで、加熱試験後の熱交換器用アルミニウム合金押出チューブのチューブ本体の平均結晶粒径を測定する試験である。なお、チューブ本体の平均結晶粒径の測定方法は、試験片を電解研磨した後、倍率50~100倍の偏光顕微鏡により、各断面の顕微鏡像を得て、円相当径を測定する方法が挙げられる。また、加熱試験の昇温過程における昇温温度については、500℃までの温度域が平均30±10℃/分の昇温速度であり、500℃以上の温度域が平均10±5℃/分の昇温速度である。
In the heating test related to the aluminum alloy extruded tube for heat exchanger, first, the aluminum alloy extruded tube for heat exchanger is heated to raise the temperature, and in the temperature raising process, it is heated to a holding temperature of 600 ° C. ± 10 ° C., and then In this test, a temperature of 600° C.±10° C. is maintained for 3 minutes, and then a heating test is performed by cooling to room temperature, and then the average crystal grain size of the tube body of the aluminum alloy extruded tube for heat exchanger is measured after the heating test. The method for measuring the average crystal grain size of the tube body includes a method of electropolishing a test piece, obtaining a microscopic image of each cross section with a polarizing microscope at a magnification of 50 to 100, and measuring the equivalent circle diameter. be done. In addition, regarding the temperature increase in the heating process of the heating test, the temperature range up to 500 ° C. is an average temperature increase rate of 30 ± 10 ° C./min, and the temperature range of 500 ° C. or higher is an average of 10 ± 5 ° C./min. is the rate of temperature rise.
本発明の熱交換器用アルミニウム合金押出チューブは、上記特定のアルミニウム合金よりなるチューブ本体を有している。そのため、本発明の熱交換器用アルミニウム合金押出チューブは、チューブ本体に純アルミニウム系合金を採用する場合に比べて高い強度特性を有する。
The aluminum alloy extruded tube for a heat exchanger of the present invention has a tube main body made of the above specific aluminum alloy. Therefore, the aluminum alloy extruded tube for a heat exchanger of the present invention has higher strength characteristics than when a pure aluminum alloy is used for the tube body.
本発明の熱交換器用アルミニウム合金押出チューブの塗膜は、Al-Si合金粉末、Zn含有フッ化物系フラックス粉末及びZn非含有フッ化物系フラックス粉末を含んでいる。これらの粉末がそれぞれの特徴を発揮すると共に、相互に作用して相乗的な効果を発揮することにより、優れたろう付性及び耐食性を容易に実現することができる。
The coating film of the aluminum alloy extruded tube for heat exchangers of the present invention contains Al-Si alloy powder, Zn-containing fluoride flux powder, and Zn-free fluoride flux powder. These powders exert their respective characteristics and interact with each other to exert a synergistic effect, thereby easily realizing excellent brazeability and corrosion resistance.
すなわち、混合粉末に含まれるAl-Si合金粉末は、ろう付時の加熱によって溶融し、チューブ外表面に液相ろうを生じさせる。これにより、熱交換器用チューブとフィンとを接合させることができる。この際、チューブ外表面を溶融させることなくろう材粉末単体で液相ろうを生じるため、ろう付中にチューブ肉厚を減少させず又は非常に減少量が少なく、より薄肉のチューブを使用することができる。
That is, the Al—Si alloy powder contained in the mixed powder is melted by heating during brazing, and liquid phase brazing is generated on the outer surface of the tube. Thereby, the heat exchanger tubes and the fins can be joined. At this time, since liquid phase brazing is generated by the brazing material powder alone without melting the outer surface of the tube, the thickness of the tube should not be reduced during brazing, or the amount of reduction is very small, and a thinner tube should be used. can be done.
本発明の熱交換器用アルミニウム合金押出チューブは、塗膜中にZn含有フッ化物系フラックス粉末を1.0~9.0g/m2、好ましくは2.0~8.0g/m2含有している。例えば、Znをチューブ表面に溶射した熱交換器用チューブの場合、Zn量が少ない場合には、チューブ表面への均一なZn溶射が困難であり、Zn量が多い場合には、ろう付によりZn拡散層が形成された場合、チューブ表面とチューブ深部の電位差が大きくなり、チューブの減肉速度が速くなってしまう。また、Zn量が多い場合には、チューブ表面にろう付により形成される接合部であるフィレットのZn濃度が高くなり、フィレットが優先的に腐食し、早期のフィンの脱落を招く懸念がある。一方、Zn含有フッ化物系フラックス粉末を含む塗料を塗布して形成させた塗膜を有する熱交換器用チューブの場合、Zn含有フッ化物系フラックスの量によらずチューブ表面に均一に塗装を施すことが可能であるため、適切な量のZnをチューブ表面に付与することができる。この結果、Zn拡散層の形成により、チューブ表面とチューブ芯との間に適切な電位差が形成され、チューブ単体として優れた防食性能を有することができる。また、フィレットへのZn濃縮が低減され、耐食性が向上する。
The aluminum alloy extruded tube for heat exchanger of the present invention contains 1.0 to 9.0 g/m 2 , preferably 2.0 to 8.0 g/m 2 of Zn-containing fluoride-based flux powder in the coating film. there is For example, in the case of heat exchanger tubes in which Zn is thermally sprayed on the tube surface, uniform Zn thermal spraying on the tube surface is difficult when the amount of Zn is small, and when the amount of Zn is large, Zn diffuses due to brazing. When a layer is formed, the potential difference between the surface of the tube and the depth of the tube increases, and the rate of thinning of the tube increases. Moreover, when the amount of Zn is large, the Zn concentration in the fillets, which are joints formed on the tube surface by brazing, increases, and the fillets are preferentially corroded, which may lead to premature detachment of the fins. On the other hand, in the case of a heat exchanger tube having a coating film formed by applying a paint containing Zn-containing fluoride-based flux powder, the tube surface should be uniformly coated regardless of the amount of Zn-containing fluoride-based flux. Therefore, an appropriate amount of Zn can be applied to the tube surface. As a result, due to the formation of the Zn diffusion layer, an appropriate potential difference is formed between the tube surface and the tube core, and the tube itself can have excellent anti-corrosion performance. In addition, Zn concentration in fillets is reduced, and corrosion resistance is improved.
本発明の熱交換器用アルミニウム合金押出チューブは、塗膜中にZn含有フッ化物系フラックス粉末と共に、Zn非含有フッ化物系フラックス粉末を含有し、Zn含有フッ化物系フラックス粉末及びZn非含有フッ化物系フラックス粉末は、ろう付時の加熱によって溶融し、ろう材粉末表面の酸化皮膜およびチューブ外表面の酸化皮膜を先んじて破壊することで、Al-Si合金粉末の溶融後ただちにろう付を可能にする。そして、本発明の熱交換器用アルミニウム合金押出チューブでは、Zn非含有フッ化物系フラックス粉末が、Zn含有フッ化物系フラックス粉末だけでは不足するろう材粉末表面の酸化皮膜およびチューブ外表面の酸化皮膜の破壊作用を補充するので、ろう付後のチューブ表面とチューブ深部の電位差を適切にし、ろう付時のフィレットへのZnの濃縮を少なくしつつも、ろう付性を良好にすることができる。
The aluminum alloy extruded tube for a heat exchanger of the present invention contains a Zn-containing fluoride-based flux powder and a Zn-free fluoride-based flux powder in the coating film, and the Zn-containing fluoride-based flux powder and the Zn-free fluoride The system flux powder is melted by heating during brazing, and destroys the oxide film on the surface of the brazing material powder and the oxide film on the outer surface of the tube first, making it possible to braze immediately after melting the Al-Si alloy powder. do. In the aluminum alloy extruded tube for a heat exchanger of the present invention, the Zn-free fluoride-based flux powder is used to form the oxide film on the surface of the brazing material powder and the oxide film on the outer surface of the tube, which are insufficient with the Zn-containing fluoride-based flux powder alone. Since it replenishes the destructive action, the potential difference between the surface of the tube after brazing and the deep part of the tube can be made appropriate, and while the concentration of Zn in the fillet during brazing is reduced, the brazeability can be improved.
以上のように、本発明の熱交換器用アルミニウム合金押出チューブは、より薄肉であっても外表面の溶融を生じず又は生じ難く優れたろう付性を有する。また、熱交換器用アルミニウム合金押出チューブは、塗膜に含まれたZn含有フッ化物系フラックス粉末がろう付加熱中にチューブと反応することでZnを生成し、チューブ表面からZnが拡散することで犠牲層を有しチューブ単体として犠牲防食効果を発揮し、同時にフィレットへのZn濃縮が低減され、優れた耐食性を有する。
As described above, the aluminum alloy extruded tube for a heat exchanger of the present invention does not or hardly causes melting of the outer surface even if it is thinner, and has excellent brazeability. In the aluminum alloy extruded tube for heat exchangers, Zn-containing fluoride-based flux powder contained in the coating reacts with the tube during brazing addition heat to generate Zn, and Zn diffuses from the tube surface to sacrifice It has a layer and exhibits a sacrificial anti-corrosion effect as a single tube, and at the same time, Zn concentration in the fillet is reduced, and it has excellent corrosion resistance.
(熱交換器)
本発明の第一の形態の熱交換器は、Znを含有するアルミニウム合金からなるフィンと本発明の熱交換器用アルミニウム合金押出チューブとがろう付により接合されたものである。 (Heat exchanger)
A heat exchanger according to a first aspect of the present invention is obtained by brazing fins made of an aluminum alloy containing Zn and extruded aluminum alloy tubes for a heat exchanger of the present invention.
本発明の第一の形態の熱交換器は、Znを含有するアルミニウム合金からなるフィンと本発明の熱交換器用アルミニウム合金押出チューブとがろう付により接合されたものである。 (Heat exchanger)
A heat exchanger according to a first aspect of the present invention is obtained by brazing fins made of an aluminum alloy containing Zn and extruded aluminum alloy tubes for a heat exchanger of the present invention.
本発明の第一の形態の熱交換器に係るZnを含有するアルミニウム合金からなるフィンは、アルミニウム合金により形成されている。フィン材を形成するアルミニウム合金は、特に制限されず、熱交換器用として十分な強度及び耐食性を有するものであればよいが、例えば、Mn含有量が0.80~2.00質量%、Zn含有量が0.50~2.50質量%、Cu含有量が0.30質量%以下であり、残部Al及び不可避不純物からなるアルミニウム合金が挙げられる。また、前記フィン材用アルミニウム合金は、更に、Siを1.50質量%以下、及び/又はZrを0.30質量%以下含有してもよい。また、本発明の熱交換器に係るZnを含有するアルミニウム合金からなるフィンは、熱交換器用として十分な強度及び耐食性を有するものであれば、公知のフィンであってもよい。
The fins made of an aluminum alloy containing Zn according to the heat exchanger of the first embodiment of the present invention are made of an aluminum alloy. The aluminum alloy forming the fin material is not particularly limited as long as it has sufficient strength and corrosion resistance for use in heat exchangers. 0.50 to 2.50% by mass, a Cu content of 0.30% by mass or less, and the balance being Al and unavoidable impurities. The aluminum alloy for fin material may further contain 1.50% by mass or less of Si and/or 0.30% by mass or less of Zr. Further, the fins made of an aluminum alloy containing Zn according to the heat exchanger of the present invention may be known fins as long as they have sufficient strength and corrosion resistance for use in heat exchangers.
本発明の第一の形態の熱交換器は、本発明の熱交換器用アルミニウム合金押出チューブに、Znを含有するアルミニウム合金からなるフィンを当接させた後、ヘッダ等の他の部材を組み付け、これらを加熱して、ろう付することにより作製される。ろう付に際しての加熱温度、加熱時間、雰囲気は、特に制限されず、ろう付方法も、特に制限されない。ろう付の加熱温度は、例えば、590~610℃であり、また、ろう付の加熱時間は、例えば、15分~45分であり、また、ろう付の雰囲気は、例えば、窒素ガス雰囲気、アルゴンガス雰囲気等である。
In the heat exchanger of the first aspect of the present invention, after contacting the aluminum alloy extruded tube for heat exchanger of the present invention with fins made of an aluminum alloy containing Zn, other members such as a header are assembled, It is produced by heating and brazing these. The heating temperature, heating time, and atmosphere for brazing are not particularly limited, and the brazing method is also not particularly limited. The heating temperature for brazing is, for example, 590 to 610° C., the heating time for brazing is, for example, 15 minutes to 45 minutes, and the atmosphere for brazing is, for example, nitrogen gas atmosphere, argon A gas atmosphere or the like.
本発明の第一の形態の熱交換器では、自然電位測定において、アルミニウム合金押出チューブのチューブ表面とチューブ深部との電位差(チューブ表面の電位-チューブ深部の電位)が、-180~-40mV、好ましくは-150~-40mVである。アルミニウム合金押出チューブのチューブ表面とチューブ深部との電位差が、上記範囲にあることにより、押出チューブのチューブ表面近傍に形成されているZn拡散層が十分な犠牲防食効果を発揮し、チューブ単体として優れた防食性能を有する。
In the heat exchanger of the first embodiment of the present invention, in self-potential measurement, the potential difference between the tube surface and the tube depth of the aluminum alloy extruded tube (tube surface potential - tube depth potential) is -180 to -40 mV, It is preferably -150 to -40 mV. Since the potential difference between the tube surface and the tube depth of the aluminum alloy extruded tube is within the above range, the Zn diffusion layer formed near the tube surface of the extruded tube exhibits a sufficient sacrificial anti-corrosion effect, making the tube excellent as a single unit. It has anti-corrosion performance.
本発明の第一の形態の熱交換器は、チューブ材として、本発明の熱交換器用アルミニウム合金押出チューブを用いて、ろう付されたものなので、ろう付時にチューブ肉厚を減少させることなく又は非常に肉厚の減少量が少なくフィンと接合されたものである。そのため、本発明の熱交換器は、薄肉であっても強度が高い。また、ろう付後のチューブ表面とチューブ深部の電位差が適切であるため、犠牲陽極効果により孔食が抑制されつつも、チューブの減肉速度が速すぎず、優れた耐食性を有する。
The heat exchanger of the first aspect of the present invention is brazed using the aluminum alloy extruded tube for heat exchanger of the present invention as a tube material, so that the thickness of the tube is not reduced during brazing. It is joined to the fin with a very small decrease in thickness. Therefore, the heat exchanger of the present invention has high strength even if it is thin. In addition, since the potential difference between the surface of the tube after brazing and the depth of the tube is appropriate, pitting corrosion is suppressed by the sacrificial anode effect, but the rate of thinning of the tube is not too fast, providing excellent corrosion resistance.
本発明の第一の形態の熱交換器は、本発明の熱交換器用チューブと、Znを含有するアルミニウム合金からなるフィンとがろう付により接合されている。ろう付の際にはチューブとフィンとの間にフィレットを形成する。一般に塗膜中に純Zn粉末等を含む場合には、前述の通りフィレット形成時に溶融ろう中のZnが濃縮し、フィレットの電位が最も卑になる。この場合、熱交換器が腐食環境下にさらされるとフィレット部分の腐食が最も早く進行するため、フィレットが消失することでフィンがチューブ表面から脱落する。その結果、熱交換性能が大きく低下し、さらにフィンによるチューブの防食作用が失われるため、早期にチューブの貫通を生じ得る。
In the heat exchanger of the first embodiment of the present invention, the heat exchanger tubes of the present invention and fins made of an aluminum alloy containing Zn are joined by brazing. A fillet is formed between the tube and the fins during brazing. In general, when pure Zn powder or the like is contained in the coating film, Zn in the molten brazing filler metal is concentrated during fillet formation as described above, and the potential of the fillet becomes the most negative. In this case, when the heat exchanger is exposed to a corrosive environment, corrosion progresses most rapidly in the fillet portions, and the disappearance of the fillets causes the fins to come off the tube surface. As a result, the heat exchange performance is greatly reduced, and furthermore, the anti-corrosion action of the tube by the fins is lost, so that the tube may penetrate at an early stage.
一方、本発明においては熱交換器用アルミニウム合金押出チューブに塗装された塗膜中にZn成分が含有されているものの、従来技術に比べフィレットへのZn濃縮を生じない。すなわち、フィレットが優先的に腐食しないため長期間に亘ってチューブ表面からフィンが脱落せず、熱交換性能の低下を防止できるだけでなく、フィンによるチューブの防食作用が長期間得られる。それ故、上述したように、過酷な腐食環境下にさらされても優れた耐食性を有する。
On the other hand, in the present invention, although the Zn component is contained in the coating film applied to the aluminum alloy extruded tube for heat exchanger, Zn concentration in the fillet does not occur as compared with the conventional technology. That is, since the fillets do not corrode preferentially, the fins do not fall off from the tube surface for a long period of time, and not only is it possible to prevent deterioration in heat exchange performance, but the fins provide a long-term anti-corrosion effect on the tube. Therefore, as described above, it has excellent corrosion resistance even when exposed to a severe corrosive environment.
また、本発明の第二の形態の熱交換器は、Mnを含有するアルミニウム合金からなるアルミニウム合金押出チューブと、該アルミニウム押出チューブにろう付接合されており、Znを含有するアルミニウム合金からなるフィンと、を有し、
該アルミニウム合金押出チューブは、チューブ表面にZn拡散層を有し、
チューブ表面とチューブ深部との電位差(チューブ表面の電位-チューブ深部の電位)が、-180~-40mVであること、
を特徴とする熱交換器である。 A heat exchanger according to a second aspect of the present invention comprises an aluminum alloy extruded tube made of an aluminum alloy containing Mn, and a fin made of an aluminum alloy containing Zn, brazed to the extruded aluminum tube. and
The aluminum alloy extruded tube has a Zn diffusion layer on the tube surface,
The potential difference between the tube surface and the tube depth (tube surface potential - tube depth potential) is -180 to -40 mV,
A heat exchanger characterized by
該アルミニウム合金押出チューブは、チューブ表面にZn拡散層を有し、
チューブ表面とチューブ深部との電位差(チューブ表面の電位-チューブ深部の電位)が、-180~-40mVであること、
を特徴とする熱交換器である。 A heat exchanger according to a second aspect of the present invention comprises an aluminum alloy extruded tube made of an aluminum alloy containing Mn, and a fin made of an aluminum alloy containing Zn, brazed to the extruded aluminum tube. and
The aluminum alloy extruded tube has a Zn diffusion layer on the tube surface,
The potential difference between the tube surface and the tube depth (tube surface potential - tube depth potential) is -180 to -40 mV,
A heat exchanger characterized by
本発明の第二の形態の熱交換器に係るアルミニウム合金押出チューブは、Mnを含有するアルミニウム合金からなり、本発明の第二の形態の熱交換器に係るアルミニウム合金押出チューブ中のMn含有量は、好ましくは0.20~1.20質量%、特に好ましくは0.40~1.20質量%である。また、本発明の第二の形態の熱交換器に係るアルミニウム合金押出チューブは、Tiを含有することができ、本発明の第二の形態の熱交換器に係るアルミニウム合金押出チューブ中のTi含有量は、好ましくは0.10質量%以下、特に好ましくは0.001~0.08質量%である。また、本発明の第二の形態の熱交換器に係るアルミニウム合金押出チューブは、チューブ表面にZn拡散層を有する。
The aluminum alloy extruded tube according to the second aspect of the heat exchanger of the present invention is made of an aluminum alloy containing Mn, and the Mn content in the aluminum alloy extruded tube according to the second aspect of the heat exchanger of the present invention is is preferably 0.20 to 1.20% by weight, particularly preferably 0.40 to 1.20% by weight. Further, the aluminum alloy extruded tube according to the second aspect of the heat exchanger of the present invention can contain Ti, and the Ti content in the aluminum alloy extruded tube according to the second aspect of the heat exchanger of the present invention is The amount is preferably 0.10% by weight or less, particularly preferably 0.001 to 0.08% by weight. Also, the aluminum alloy extruded tube according to the second embodiment of the heat exchanger of the present invention has a Zn diffusion layer on the tube surface.
本発明の第二の形態の熱交換器に係るフィン材を形成するアルミニウム合金は、特に制限されず、熱交換器用として十分な強度及び耐食性を有するものであればよいが、例えば、Mn含有量が0.80~2.00質量%、Zn含有量が0.50~2.50質量%、Cu含有量が0.30質量%以下であるアルミニウム合金が挙げられる。前記フィン材用アルミニウム合金は、Siを1.50質量%以下及び/又はZrを0.30質量%以下含有してもよい。
The aluminum alloy forming the fin material of the heat exchanger according to the second embodiment of the present invention is not particularly limited as long as it has sufficient strength and corrosion resistance for heat exchangers. is 0.80 to 2.00% by mass, the Zn content is 0.50 to 2.50% by mass, and the Cu content is 0.30% by mass or less. The aluminum alloy for fin material may contain 1.50% by mass or less of Si and/or 0.30% by mass or less of Zr.
本発明の第二の形態の熱交換器では、自然電位測定において、アルミニウム合金押出チューブのチューブ表面とチューブ深部との電位差(チューブ表面の電位-チューブ深部の電位)が、-180~-40mV、好ましくは-150~-40mVである。アルミニウム合金押出チューブのチューブ表面とチューブ深部との電位差が、上記範囲にあることにより、押出チューブのチューブ表面近傍に形成されているZn拡散層が十分な犠牲防食効果を発揮し、チューブ単体として優れた防食性能を有する。
In the heat exchanger of the second aspect of the present invention, in the self-potential measurement, the potential difference between the tube surface and the tube depth of the aluminum alloy extruded tube (tube surface potential - tube depth potential) is -180 to -40 mV, It is preferably -150 to -40 mV. Since the potential difference between the tube surface and the tube depth of the aluminum alloy extruded tube is within the above range, the Zn diffusion layer formed near the tube surface of the extruded tube exhibits a sufficient sacrificial anti-corrosion effect, making the tube excellent as a single unit. It has anti-corrosion performance.
以下に、実施例を示して、本発明を具体的に説明するが、本発明は、以下に示す実施例に限定されるものではない。
The present invention will be specifically described below with reference to examples, but the present invention is not limited to the examples shown below.
(実施例及び比較例)
表1に示す化学成分を有する合金を用いてチューブ本体を作製し、次いで、得られたチューブ本体の表面に表2に示す組成の塗膜を形成させて、アルミニウム合金押出チューブを作製した。その後、得られたアルミニウム合金押出チューブを用いて図1に示すような熱交換器を模擬したミニコアを組み立て、得られた3種のミニコアの耐食性について評価を行った。 (Examples and Comparative Examples)
A tube body was produced using an alloy having the chemical components shown in Table 1, and then a coating film having a composition shown in Table 2 was formed on the surface of the obtained tube body to produce an aluminum alloy extruded tube. After that, using the obtained aluminum alloy extruded tube, a mini-core simulating a heat exchanger as shown in FIG. 1 was assembled, and the corrosion resistance of the obtained three types of mini-cores was evaluated.
表1に示す化学成分を有する合金を用いてチューブ本体を作製し、次いで、得られたチューブ本体の表面に表2に示す組成の塗膜を形成させて、アルミニウム合金押出チューブを作製した。その後、得られたアルミニウム合金押出チューブを用いて図1に示すような熱交換器を模擬したミニコアを組み立て、得られた3種のミニコアの耐食性について評価を行った。 (Examples and Comparative Examples)
A tube body was produced using an alloy having the chemical components shown in Table 1, and then a coating film having a composition shown in Table 2 was formed on the surface of the obtained tube body to produce an aluminum alloy extruded tube. After that, using the obtained aluminum alloy extruded tube, a mini-core simulating a heat exchanger as shown in FIG. 1 was assembled, and the corrosion resistance of the obtained three types of mini-cores was evaluated.
<チューブ本体の作製>
表1に示す化学成分を有するビレットを600℃で10時間加熱して均質化処理を行った。均質化処理が完了したビレットを室温まで冷却した後、450℃まで再加熱し、熱間押出加工を行った。以上により、幅が16mm、高さが1.0mmの押出方向に垂直な断面が扁平な形状を呈し、複数の冷媒流路を備えたチューブ本体を作製した。 <Production of tube body>
A billet having the chemical components shown in Table 1 was heated at 600° C. for 10 hours for homogenization. After the homogenized billet was cooled to room temperature, it was reheated to 450° C. and subjected to hot extrusion. As described above, a tube body having a width of 16 mm, a height of 1.0 mm, a flat cross section perpendicular to the extrusion direction, and a plurality of coolant channels was produced.
表1に示す化学成分を有するビレットを600℃で10時間加熱して均質化処理を行った。均質化処理が完了したビレットを室温まで冷却した後、450℃まで再加熱し、熱間押出加工を行った。以上により、幅が16mm、高さが1.0mmの押出方向に垂直な断面が扁平な形状を呈し、複数の冷媒流路を備えたチューブ本体を作製した。 <Production of tube body>
A billet having the chemical components shown in Table 1 was heated at 600° C. for 10 hours for homogenization. After the homogenized billet was cooled to room temperature, it was reheated to 450° C. and subjected to hot extrusion. As described above, a tube body having a width of 16 mm, a height of 1.0 mm, a flat cross section perpendicular to the extrusion direction, and a plurality of coolant channels was produced.
<塗膜の形成>
チューブ本体の作製とは別に、塗膜を形成するためのペーストを準備した。Al-Si合金ろう材粉末、Zn非含有フッ化物系フラックス粉末、Zn含有フッ化物系フラックス粉末およびバインダを溶剤に混合し、塗膜形成用のペーストを調整した。次いで、得られたペーストを、上記チューブ本体の平坦面に、ロールコーターを用いて塗布し、塗装チューブを得た。塗装後のペーストの組成は表2の通りとした。 <Formation of coating film>
A paste for forming a coating film was prepared separately from the production of the tube body. Al--Si alloy brazing powder, Zn-free fluoride flux powder, Zn-containing fluoride flux powder and a binder were mixed with a solvent to prepare a paste for forming a coating film. Next, the obtained paste was applied to the flat surface of the tube body using a roll coater to obtain a coated tube. The composition of the paste after coating was as shown in Table 2.
チューブ本体の作製とは別に、塗膜を形成するためのペーストを準備した。Al-Si合金ろう材粉末、Zn非含有フッ化物系フラックス粉末、Zn含有フッ化物系フラックス粉末およびバインダを溶剤に混合し、塗膜形成用のペーストを調整した。次いで、得られたペーストを、上記チューブ本体の平坦面に、ロールコーターを用いて塗布し、塗装チューブを得た。塗装後のペーストの組成は表2の通りとした。 <Formation of coating film>
A paste for forming a coating film was prepared separately from the production of the tube body. Al--Si alloy brazing powder, Zn-free fluoride flux powder, Zn-containing fluoride flux powder and a binder were mixed with a solvent to prepare a paste for forming a coating film. Next, the obtained paste was applied to the flat surface of the tube body using a roll coater to obtain a coated tube. The composition of the paste after coating was as shown in Table 2.
なお、Al-Si合金ろう材粉末は、Si含有量12.00質量%であり、Zn非含有フッ化物系フラックス粉末は、K-Al-F系フラックスであり、Zn含有フッ化物系フラックスは、KZnF3であり、バインダはアクリル樹脂とした。
The Al—Si alloy brazing filler metal powder has a Si content of 12.00% by mass, the Zn-free fluoride-based flux powder is a K—Al—F-based flux, and the Zn-containing fluoride-based flux is It was KZnF3 and the binder was an acrylic resin.
<フィンの作製>
Mn:1.20質量%、Zn:1.50質量%のアルミニウム合金からなる厚さ0.1mmの板材にコルゲート加工を施し、コルゲート形状を有するフィンを作製した。なお、フィンピッチは3mmとし、フィン高さは7mmとした。 <Fabrication of fins>
A 0.1 mm thick plate made of an aluminum alloy containing Mn: 1.20% by mass and Zn: 1.50% by mass was corrugated to produce a fin having a corrugated shape. The fin pitch was 3 mm and the fin height was 7 mm.
Mn:1.20質量%、Zn:1.50質量%のアルミニウム合金からなる厚さ0.1mmの板材にコルゲート加工を施し、コルゲート形状を有するフィンを作製した。なお、フィンピッチは3mmとし、フィン高さは7mmとした。 <Fabrication of fins>
A 0.1 mm thick plate made of an aluminum alloy containing Mn: 1.20% by mass and Zn: 1.50% by mass was corrugated to produce a fin having a corrugated shape. The fin pitch was 3 mm and the fin height was 7 mm.
<ミニコア作製および加熱試験>
フィンの上下をアルミニウム合金押出チューブで挟む形で積層し、図1に示す所定の形状に組み付けた。この状態で、窒素ガス雰囲気下で、チューブおよびフィンを400℃以上の領域を平均10℃毎分の昇温速度で600℃まで昇温させ、600℃の温度を3分間保持した後室温まで降温させることにより、ろう付を行うことにより、長さ40mmに切断したチューブおよびフィンを接合し、熱交換器を模擬したミニコアを得た。
なお、ミニコア作製のための熱履歴は、加熱試験の熱履歴に相当する。 <Mini-core preparation and heating test>
The upper and lower fins were laminated in such a manner that they were sandwiched between aluminum alloy extruded tubes, and assembled into a predetermined shape shown in FIG. In this state, in a nitrogen gas atmosphere, the temperature of the tube and fins was raised to 600°C at an average heating rate of 10°C per minute in the region of 400°C or higher, and the temperature was maintained at 600°C for 3 minutes, and then cooled to room temperature. By brazing, the tube cut to a length of 40 mm and the fins were joined to obtain a mini-core simulating a heat exchanger.
Note that the thermal history for producing the mini-core corresponds to the thermal history of the heating test.
フィンの上下をアルミニウム合金押出チューブで挟む形で積層し、図1に示す所定の形状に組み付けた。この状態で、窒素ガス雰囲気下で、チューブおよびフィンを400℃以上の領域を平均10℃毎分の昇温速度で600℃まで昇温させ、600℃の温度を3分間保持した後室温まで降温させることにより、ろう付を行うことにより、長さ40mmに切断したチューブおよびフィンを接合し、熱交換器を模擬したミニコアを得た。
なお、ミニコア作製のための熱履歴は、加熱試験の熱履歴に相当する。 <Mini-core preparation and heating test>
The upper and lower fins were laminated in such a manner that they were sandwiched between aluminum alloy extruded tubes, and assembled into a predetermined shape shown in FIG. In this state, in a nitrogen gas atmosphere, the temperature of the tube and fins was raised to 600°C at an average heating rate of 10°C per minute in the region of 400°C or higher, and the temperature was maintained at 600°C for 3 minutes, and then cooled to room temperature. By brazing, the tube cut to a length of 40 mm and the fins were joined to obtain a mini-core simulating a heat exchanger.
Note that the thermal history for producing the mini-core corresponds to the thermal history of the heating test.
以上により得られた3種のミニコア(試験体A~C)を用いて、ろう付性評価、自然電位測定、腐食試験を行った。
Using the three types of mini-cores (test specimens A to C) obtained above, brazeability evaluation, self-potential measurement, and corrosion tests were performed.
<ろう付性評価>
ろう付後のチューブの断面観察を行い、目視観察により、フィンの接合状態、変色等の外観不良の有無、フィンの溶融の有無、チューブ表面のエロージョンの有無を判定した。また、エッチングを施し、平均結晶粒径を測定した。平均結晶粒径の測定は、チューブ表面を電解研磨した後、倍率25倍の偏光顕微鏡により、チューブ表面から深さ10μm以下の断面の顕微鏡像を得て、チューブ長手方向と平行方向および直角方向に1mmの線分を各3本引き、線分の長さ1mmを、各線分と交差する結晶粒界の数で割った値の平均値を、平均結晶粒径とした。 <Brazability evaluation>
The cross section of the brazed tube was observed, and by visual observation, the bonding state of the fins, the presence or absence of appearance defects such as discoloration, the presence or absence of melting of the fins, and the presence or absence of erosion on the tube surface were determined. Etching was also performed, and the average crystal grain size was measured. The average crystal grain size is measured by electropolishing the tube surface and then using a polarizing microscope with a magnification of 25 to obtain a microscopic image of a cross section at a depth of 10 μm or less from the tube surface. Three 1 mm line segments were drawn, and the average value obtained by dividing the 1 mm length of the line segment by the number of grain boundaries intersecting each line segment was taken as the average grain size.
ろう付後のチューブの断面観察を行い、目視観察により、フィンの接合状態、変色等の外観不良の有無、フィンの溶融の有無、チューブ表面のエロージョンの有無を判定した。また、エッチングを施し、平均結晶粒径を測定した。平均結晶粒径の測定は、チューブ表面を電解研磨した後、倍率25倍の偏光顕微鏡により、チューブ表面から深さ10μm以下の断面の顕微鏡像を得て、チューブ長手方向と平行方向および直角方向に1mmの線分を各3本引き、線分の長さ1mmを、各線分と交差する結晶粒界の数で割った値の平均値を、平均結晶粒径とした。 <Brazability evaluation>
The cross section of the brazed tube was observed, and by visual observation, the bonding state of the fins, the presence or absence of appearance defects such as discoloration, the presence or absence of melting of the fins, and the presence or absence of erosion on the tube surface were determined. Etching was also performed, and the average crystal grain size was measured. The average crystal grain size is measured by electropolishing the tube surface and then using a polarizing microscope with a magnification of 25 to obtain a microscopic image of a cross section at a depth of 10 μm or less from the tube surface. Three 1 mm line segments were drawn, and the average value obtained by dividing the 1 mm length of the line segment by the number of grain boundaries intersecting each line segment was taken as the average grain size.
<自然電位測定>
ろう付後の各試験体のチューブ表面、チューブ深部の自然電位を測定した。各部位を適切な大きさに切断し、測定する部分以外をシーラントにてマスキングし、5%NaCl溶液に24h浸漬し、18hから24hまでの平均値より各部位の自然電位を求めた。アルミニウム合金押出チューブのチューブ深部の電位については、アルミニウム合金押出チューブの外表面から深さ150μmの位置の電位を測定した。
「チューブ表面の電位(A)-チューブ深部の電位(B)」については、-180~-40mVの場合を「合格」、-180mVより小さい場合又は-40mVより大きい場合を「不合格」とした。 <Spontaneous potential measurement>
After brazing, the self-potential of the tube surface and tube depth of each specimen was measured. Each site was cut to an appropriate size, masked with a sealant except for the area to be measured, immersed in a 5% NaCl solution for 24 hours, and the self-potential of each site was obtained from the average value from 18 hours to 24 hours. As for the potential at the deep portion of the aluminum alloy extruded tube, the potential at a depth of 150 μm from the outer surface of the aluminum alloy extruded tube was measured.
Regarding "tube surface potential (A) - tube deep potential (B)", -180 to -40 mV was "passed", and less than -180 mV or greater than -40 mV was "failed". .
ろう付後の各試験体のチューブ表面、チューブ深部の自然電位を測定した。各部位を適切な大きさに切断し、測定する部分以外をシーラントにてマスキングし、5%NaCl溶液に24h浸漬し、18hから24hまでの平均値より各部位の自然電位を求めた。アルミニウム合金押出チューブのチューブ深部の電位については、アルミニウム合金押出チューブの外表面から深さ150μmの位置の電位を測定した。
「チューブ表面の電位(A)-チューブ深部の電位(B)」については、-180~-40mVの場合を「合格」、-180mVより小さい場合又は-40mVより大きい場合を「不合格」とした。 <Spontaneous potential measurement>
After brazing, the self-potential of the tube surface and tube depth of each specimen was measured. Each site was cut to an appropriate size, masked with a sealant except for the area to be measured, immersed in a 5% NaCl solution for 24 hours, and the self-potential of each site was obtained from the average value from 18 hours to 24 hours. As for the potential at the deep portion of the aluminum alloy extruded tube, the potential at a depth of 150 μm from the outer surface of the aluminum alloy extruded tube was measured.
Regarding "tube surface potential (A) - tube deep potential (B)", -180 to -40 mV was "passed", and less than -180 mV or greater than -40 mV was "failed". .
<腐食試験>
各試験体にASTM-G85-Annex A3に規定されたSWAATを1320時間実施した。試験完了後の試験材を目視で観察することにより、フィンの剥離の有無を判定した。また、焦点深度測定により選定したチューブの最大腐食部について、機械研磨により断面を出し、倍率50倍の金属顕微鏡により、チューブ長手方向と平行方向の断面の顕微鏡像を得て、最大腐食部を含むチューブ長手方向に2mmの領域のチューブ断面積を、腐食試験前のチューブ断面積で割った値を、チューブ断面積減少率とした。
フィン剥がれについては、チューブとフィンが固定されており、力を加えてもチューブとフィンが固定されている場合を「◎:合格、フィン剥がれが非常に少ない」とし、チューブとフィンの接合部が一部剥離しているものの、チューブとフィンが分離していない場合を「〇:合格、フィン剥がれが少ない」とし、チューブとフィンの接点でフィンが分離している場合を「×:不合格、フィン剥がれが多い」とした。
チューブ断面積減少率が、20%以下の場合を「合格」、20%を超える場合を「不合格」とした。 <Corrosion test>
Each specimen was subjected to SWAAT specified in ASTM-G85-Annex A3 for 1320 hours. The presence or absence of peeling of the fins was determined by visually observing the test material after the completion of the test. In addition, for the maximum corroded portion of the tube selected by the depth of focus measurement, a cross section was obtained by mechanical polishing, and a microscope image of the cross section in the direction parallel to the longitudinal direction of the tube was obtained using a metallographic microscope with a magnification of 50 times, including the maximum corroded portion. The tube cross-sectional area reduction rate was obtained by dividing the tube cross-sectional area in a region of 2 mm in the longitudinal direction of the tube by the tube cross-sectional area before the corrosion test.
Regarding peeling of fins, if the tube and fins are fixed and force is applied, the tube and fins are fixed together. If the tube and fins are not separated from each other, even though the tube is partially peeled off, it is evaluated as "○: Passed, little fin peeling". A lot of fins come off."
When the tube cross-sectional area reduction rate was 20% or less, it was evaluated as "accepted", and when it exceeded 20%, it was evaluated as "failed".
各試験体にASTM-G85-Annex A3に規定されたSWAATを1320時間実施した。試験完了後の試験材を目視で観察することにより、フィンの剥離の有無を判定した。また、焦点深度測定により選定したチューブの最大腐食部について、機械研磨により断面を出し、倍率50倍の金属顕微鏡により、チューブ長手方向と平行方向の断面の顕微鏡像を得て、最大腐食部を含むチューブ長手方向に2mmの領域のチューブ断面積を、腐食試験前のチューブ断面積で割った値を、チューブ断面積減少率とした。
フィン剥がれについては、チューブとフィンが固定されており、力を加えてもチューブとフィンが固定されている場合を「◎:合格、フィン剥がれが非常に少ない」とし、チューブとフィンの接合部が一部剥離しているものの、チューブとフィンが分離していない場合を「〇:合格、フィン剥がれが少ない」とし、チューブとフィンの接点でフィンが分離している場合を「×:不合格、フィン剥がれが多い」とした。
チューブ断面積減少率が、20%以下の場合を「合格」、20%を超える場合を「不合格」とした。 <Corrosion test>
Each specimen was subjected to SWAAT specified in ASTM-G85-Annex A3 for 1320 hours. The presence or absence of peeling of the fins was determined by visually observing the test material after the completion of the test. In addition, for the maximum corroded portion of the tube selected by the depth of focus measurement, a cross section was obtained by mechanical polishing, and a microscope image of the cross section in the direction parallel to the longitudinal direction of the tube was obtained using a metallographic microscope with a magnification of 50 times, including the maximum corroded portion. The tube cross-sectional area reduction rate was obtained by dividing the tube cross-sectional area in a region of 2 mm in the longitudinal direction of the tube by the tube cross-sectional area before the corrosion test.
Regarding peeling of fins, if the tube and fins are fixed and force is applied, the tube and fins are fixed together. If the tube and fins are not separated from each other, even though the tube is partially peeled off, it is evaluated as "○: Passed, little fin peeling". A lot of fins come off."
When the tube cross-sectional area reduction rate was 20% or less, it was evaluated as "accepted", and when it exceeded 20%, it was evaluated as "failed".
<評価結果>
ろう付性評価結果を表3に示す。
試験例A、B、Cはろう付不具合を生じず、ろう付性に関しては合格であった。また、ろう付後組織の平均結晶粒径は、150μm以上と充分に大きく、エロージョンも生じず、合格であった。また、ろう付後のチューブの肉厚は、ろう付前の肉厚と比べて、大きく変化していないことから、顕著な溶融が起こっていないことが確認された。 <Evaluation results>
Table 3 shows the brazeability evaluation results.
Test Examples A, B, and C did not cause any brazing defects and passed the brazing properties. In addition, the average grain size of the post-brazing structure was sufficiently large as 150 μm or more, and no erosion occurred, which was acceptable. In addition, since the wall thickness of the tube after brazing did not change significantly compared to the wall thickness before brazing, it was confirmed that significant melting did not occur.
ろう付性評価結果を表3に示す。
試験例A、B、Cはろう付不具合を生じず、ろう付性に関しては合格であった。また、ろう付後組織の平均結晶粒径は、150μm以上と充分に大きく、エロージョンも生じず、合格であった。また、ろう付後のチューブの肉厚は、ろう付前の肉厚と比べて、大きく変化していないことから、顕著な溶融が起こっていないことが確認された。 <Evaluation results>
Table 3 shows the brazeability evaluation results.
Test Examples A, B, and C did not cause any brazing defects and passed the brazing properties. In addition, the average grain size of the post-brazing structure was sufficiently large as 150 μm or more, and no erosion occurred, which was acceptable. In addition, since the wall thickness of the tube after brazing did not change significantly compared to the wall thickness before brazing, it was confirmed that significant melting did not occur.
自然電位測定結果および腐食試験結果を表4に示す。
試験体A、Bは、チューブ表面の自然電位がチューブ深部より40mV以上卑であり、チューブ表面の優先腐食によりチューブ深部を防食可能であり、且つ、チューブ表面の自然電位とチューブ深部の自然電位の差が180mV以内であり、チューブ表面の自然電位がチューブ深部より卑になり過ぎておらず適度な電位差であり、腐食試験前後のチューブ断面積減少率は20%以下となり、合格であった。また、試験例Aは、フィン剥がれは極めて軽微であり合格であった。試験体Bは、フィン剥がれは軽微であり合格であった。いずれの試験体においても、塗装中のZn含有フラックス量が適切であり、フィレットの優先腐食が生じにくかった。
試験体Cは、フィン剥がれは軽微であり合格であったが、チューブ表面の自然電位とチューブ深部の自然電位の差が180mVより大きいためにチューブの腐食速度が大きく、腐食試験前後のチューブ断面積減少率は20%より大きくなり、不合格であった。 Table 4 shows the self-potential measurement results and the corrosion test results.
In test specimens A and B, the natural potential of the tube surface is 40 mV or more less noble than the deep part of the tube, the corrosion of the deep part of the tube can be prevented by preferential corrosion of the tube surface, and the natural potential of the tube surface and the natural potential of the deep part of the tube The difference was within 180 mV, the natural potential of the tube surface was not too base than the depth of the tube, and the potential difference was moderate. Further, in Test Example A, the peeling of the fins was extremely slight, and the sample passed the test. Specimen B was accepted because the fin peeling was slight. In all test specimens, the amount of Zn-containing flux in the coating was appropriate, and preferential corrosion of fillets was less likely to occur.
Specimen C had slight fin peeling and passed the test, but the corrosion rate of the tube was high because the difference between the natural potential of the tube surface and the natural potential of the deep part of the tube was greater than 180 mV. The reduction rate was greater than 20% and was unacceptable.
試験体A、Bは、チューブ表面の自然電位がチューブ深部より40mV以上卑であり、チューブ表面の優先腐食によりチューブ深部を防食可能であり、且つ、チューブ表面の自然電位とチューブ深部の自然電位の差が180mV以内であり、チューブ表面の自然電位がチューブ深部より卑になり過ぎておらず適度な電位差であり、腐食試験前後のチューブ断面積減少率は20%以下となり、合格であった。また、試験例Aは、フィン剥がれは極めて軽微であり合格であった。試験体Bは、フィン剥がれは軽微であり合格であった。いずれの試験体においても、塗装中のZn含有フラックス量が適切であり、フィレットの優先腐食が生じにくかった。
試験体Cは、フィン剥がれは軽微であり合格であったが、チューブ表面の自然電位とチューブ深部の自然電位の差が180mVより大きいためにチューブの腐食速度が大きく、腐食試験前後のチューブ断面積減少率は20%より大きくなり、不合格であった。 Table 4 shows the self-potential measurement results and the corrosion test results.
In test specimens A and B, the natural potential of the tube surface is 40 mV or more less noble than the deep part of the tube, the corrosion of the deep part of the tube can be prevented by preferential corrosion of the tube surface, and the natural potential of the tube surface and the natural potential of the deep part of the tube The difference was within 180 mV, the natural potential of the tube surface was not too base than the depth of the tube, and the potential difference was moderate. Further, in Test Example A, the peeling of the fins was extremely slight, and the sample passed the test. Specimen B was accepted because the fin peeling was slight. In all test specimens, the amount of Zn-containing flux in the coating was appropriate, and preferential corrosion of fillets was less likely to occur.
Specimen C had slight fin peeling and passed the test, but the corrosion rate of the tube was high because the difference between the natural potential of the tube surface and the natural potential of the deep part of the tube was greater than 180 mV. The reduction rate was greater than 20% and was unacceptable.
Claims (6)
- 自動車用熱交換器に用いられるアルミニウム合金製の押出チューブであり、
Mnを含有するアルミニウム合金からなるチューブ本体と、
該チューブ本体の表面に形成されている塗膜と、
を有し、
該塗膜は、Al-Si合金ろう材粉末と、Zn含有フッ化物系フラックス粉末と、Zn非含有フッ化物系フラックス粉末と、バインダと、を含有しており、
該Al-Si合金ろう材粉末の塗布量が9.0~25.0g/m2であり、該Zn含有フッ化物系フラックス粉末の塗布量が1.0~9.0g/m2であり、該Zn非含有フッ化物系フラックス粉末の塗布量が1.0~11.0g/m2であり、該バインダの塗布量が1.0~13.0g/m2であること、
を特徴とする熱交換器用アルミニウム合金押出チューブ。 Aluminum alloy extruded tubes used in automobile heat exchangers,
a tube body made of an aluminum alloy containing Mn;
a coating film formed on the surface of the tube body;
has
The coating contains Al—Si alloy brazing powder, Zn-containing fluoride-based flux powder, Zn-free fluoride-based flux powder, and a binder,
The coating amount of the Al—Si alloy brazing filler metal powder is 9.0 to 25.0 g/m 2 , the coating amount of the Zn-containing fluoride flux powder is 1.0 to 9.0 g/m 2 , The coating amount of the Zn-free fluoride-based flux powder is 1.0 to 11.0 g/m 2 and the coating amount of the binder is 1.0 to 13.0 g/m 2 ;
An aluminum alloy extruded tube for a heat exchanger, characterized by: - 前記アルミニウム合金は、0.20~1.20質量%のMnと、0.10質量%以下のTiと、を含有し、残部Al及び不可避不純物からなることを特徴とする請求項1に記載の熱交換器用アルミニウム合金押出チューブ。 2. The aluminum alloy according to claim 1, wherein the aluminum alloy contains 0.20 to 1.20% by mass of Mn and 0.10% by mass or less of Ti, and the balance is Al and inevitable impurities. Aluminum alloy extruded tube for heat exchanger.
- Znを含有するアルミニウム合金からなるフィンにろう付により接合したとき、自然電位測定において、前記押出チューブのチューブ表面とチューブ深部との電位差(チューブ表面の電位-チューブ深部の電位)が、-180~-40mVとなることを特徴とする請求項1又は2記載の熱交換器用アルミニウム合金押出チューブ。 When the fins made of an aluminum alloy containing Zn are joined by brazing, the potential difference between the surface of the extruded tube and the depth of the tube (potential on the surface of the tube - potential at the depth of the tube) is -180 to -180. 3. The aluminum alloy extruded tube for a heat exchanger according to claim 1, wherein the voltage is -40 mV.
- 600℃±10℃で3分間保持し、室温まで冷却した後の平均結晶粒径を測定する加熱試験において、加熱試験後の前記チューブ本体の平均結晶粒径が150μm以上であることを特徴とする請求項1~3のいずれか1項に記載の熱交換器用アルミニウム合金押出チューブ。 In a heating test for measuring the average crystal grain size after cooling to room temperature after holding at 600° C.±10° C. for 3 minutes, the average crystal grain size of the tube body after the heating test is 150 μm or more. The aluminum alloy extruded tube for heat exchangers according to any one of claims 1 to 3.
- 請求項1~4のいずれか1項に記載された熱交換器用アルミニウム合金押出チューブと、Znを含有するアルミニウム合金からなるフィンと、のろう付け接合物であることを特徴とする熱交換器。 A heat exchanger characterized by being a brazed joint of the extruded aluminum alloy tube for a heat exchanger according to any one of claims 1 to 4 and fins made of an aluminum alloy containing Zn.
- Mnを含有するアルミニウム合金からなるアルミニウム合金押出チューブと、該アルミニウム押出チューブにろう付接合されており、Znを含有するアルミニウム合金からなるフィンと、を有し、
該アルミニウム合金押出チューブは、チューブ表面にZn拡散層を有し、
自然電位測定において、該アルミニウム合金押出チューブのチューブ表面とチューブ深部との電位差(チューブ表面の電位-チューブ深部の電位)が、-180~-40mVであること、
を特徴とする熱交換器。 An aluminum alloy extruded tube made of an aluminum alloy containing Mn, and a fin brazed to the aluminum extruded tube and made of an aluminum alloy containing Zn,
The aluminum alloy extruded tube has a Zn diffusion layer on the tube surface,
In spontaneous potential measurement, the potential difference between the tube surface and the tube depth of the aluminum alloy extruded tube (tube surface potential - tube depth potential) is -180 to -40 mV,
A heat exchanger characterized by:
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JP2006348358A (en) * | 2005-06-17 | 2006-12-28 | Mitsubishi Alum Co Ltd | Aluminum-alloy extruded material for heat-exchanger, and flat tube with multi-holes for heat-exchanger and header for heat-exchanger using the same |
JP2011007383A (en) * | 2009-06-24 | 2011-01-13 | Sumitomo Light Metal Ind Ltd | Aluminum alloy heat exchanger and method for manufacturing refrigerant passage pipe used for the same |
WO2011148781A1 (en) * | 2010-05-25 | 2011-12-01 | 住友軽金属工業株式会社 | Method for producing aluminum alloy heat exchanger |
JP4980787B2 (en) * | 2007-05-16 | 2012-07-18 | 三菱アルミニウム株式会社 | Aluminum alloy brazing paint excellent in peeling resistance of coating film, brazing aluminum alloy plate, aluminum alloy member for automobile heat exchanger using the same, and method for producing automobile heat exchanger |
JP5834624B2 (en) * | 2011-08-25 | 2015-12-24 | 日本軽金属株式会社 | Heat exchanger |
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JP2006348358A (en) * | 2005-06-17 | 2006-12-28 | Mitsubishi Alum Co Ltd | Aluminum-alloy extruded material for heat-exchanger, and flat tube with multi-holes for heat-exchanger and header for heat-exchanger using the same |
JP4980787B2 (en) * | 2007-05-16 | 2012-07-18 | 三菱アルミニウム株式会社 | Aluminum alloy brazing paint excellent in peeling resistance of coating film, brazing aluminum alloy plate, aluminum alloy member for automobile heat exchanger using the same, and method for producing automobile heat exchanger |
JP2011007383A (en) * | 2009-06-24 | 2011-01-13 | Sumitomo Light Metal Ind Ltd | Aluminum alloy heat exchanger and method for manufacturing refrigerant passage pipe used for the same |
WO2011148781A1 (en) * | 2010-05-25 | 2011-12-01 | 住友軽金属工業株式会社 | Method for producing aluminum alloy heat exchanger |
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