JP6351206B2 - High corrosion resistance aluminum alloy brazing sheet and flow path forming part for automotive heat exchanger - Google Patents

Description

  The present invention relates to a highly corrosion-resistant aluminum alloy brazing sheet, and more particularly to a highly corrosion-resistant aluminum alloy brazing sheet that is suitably used as a high-temperature compressed air or refrigerant passage component in a heat exchanger such as an intercooler. Furthermore, this invention relates to the flow-path formation component of the heat exchanger for motor vehicles using the said highly corrosion-resistant aluminum alloy brazing sheet.

  Aluminum alloys are lightweight and have high thermal conductivity, and high corrosion resistance can be realized by appropriate processing. Therefore, aluminum alloys are used as constituent materials for automotive heat exchangers such as radiators, condensers, evaporators, heaters, and intercoolers. For example, as an automotive heat exchanger tube material, an Al—Mn alloy such as 3003 alloy is used as a core material, and a brazing material of an Al—Si alloy or a sacrificial anode material of an Al—Zn alloy is provided on one side thereof. An aluminum alloy brazing sheet which is a clad two-layer clad material and a three-layer clad material obtained by clad an Al—Si alloy brazing material on the other side of the core material is used. A heat exchanger is usually manufactured by combining corrugated fins with this aluminum alloy brazing sheet and brazing and joining at a high temperature of about 600 ° C.

  If corrosive liquid is present inside or outside the tube of this heat exchanger, the tube material may burst as a result of the penetration of the tube due to the occurrence of pitting corrosion or the decrease in the tube thickness due to the uniform corrosion, resulting in a decrease in pressure resistance. There is. If the tube penetrates or ruptures, there is a risk of leakage of air, cooling water, or refrigerant circulating inside. As the corrosive liquid in this heat exchanger, for example, cooling water flows inside the tube of the radiator, and corrosive substances such as snow melting salt from the outside environment adhere to the outside of the tube. Both can be said to be in a corrosive environment.

  Conventionally, as a countermeasure against corrosion of a member such as a heat exchanger tube whose inner and outer surfaces are in a corrosive environment, a sacrificial anode material is clad to prevent corrosion inside the tube, and the outside of the tube is sacrificed to the tube itself. The layer is not clad, and the pitting potential is reduced by adding Zn to the aluminum alloy which is a constituent material of the fin, and the sacrificial anticorrosive action by the fin is utilized. The reason why the outside of the tube can be prevented from being corroded by such a method is that the corrosive liquid to be attached has high conductivity. The conductivity of the corrosive liquid increases as the concentration of the solute component increases, but in the external environment of the radiator, the corrosive liquid with a high concentration of solute components such as snow melting salt adheres to the fin. The sacrificial effect can sufficiently protect the entire tube.

  However, in new heat exchangers used in recent automobiles, due to the peculiarity of the corrosive environment outside the tube, the anticorrosion effect due to the sacrificial effect of fins like conventional radiators cannot be expected. There has been a need to use a material that has been clad.

  One example is a water-cooled intercooler. In the tube of the water-cooled type intercooler, the surface on the side in contact with the cooling water is a corrosive environment similar to that of a conventional radiator, and therefore a sacrificial anode material cladding is required. On the other hand, the opposite surface is in contact with compressed air mixed with exhaust gas. The compressed air is condensed to condense condensed water in which the exhaust gas is dissolved. Since this condensed water contains chloride ions which are exhaust gas components, it has pitting corrosion-inducing properties. Moreover, since this condensed water becomes acidic at pH 4 or less in addition to the dilute solute component, the corrosion rate is extremely fast. Furthermore, sacrificial protection with fins is difficult because it is not a submerged environment. Therefore, the sacrificial anode material clad is also required on the surface in contact with the compressed air.

  In such an aluminum alloy brazing sheet having a sacrificial anode material on both sides, it is necessary to provide both a brazing function with a fin and a sacrificial anticorrosion function on one side. As a configuration of the aluminum alloy brazing sheet having both the brazing function and the sacrificial anticorrosion function on the brazing material side surface, there are the following two modes.

  First, for a three-layer aluminum alloy brazing sheet composed of a brazing material / core material / sacrificial anode material, there is a method in which Zn is added to an Al—Si based alloy as a brazing material to lower the pitting corrosion potential. This brazing sheet imparts a sacrificial anticorrosive effect to the brazing material itself made of an Al—Si alloy, and thereby has both a brazing function with a fin and a sacrificial anticorrosive function.

  Further, as a second means, a four-layer material comprising a brazing material / intermediate layer material (having sacrificial anti-corrosion effect) / core material / sacrificial anode material clad with an intermediate layer material having a sacrificial anti-corrosion effect between the core material and the brazing material. Can be considered. The brazing sheet having such a configuration is described in Patent Documents 1 and 2. The brazing sheet described in Patent Document 1 has an Al-Zn alloy intermediate layer material between a core material and a brazing material, and a sacrificial anode material on the surface of the core material that does not have the intermediate layer material Has a sacrificial anticorrosive effect on both sides of the tube. In addition, the brazing sheet described in Patent Document 2 similarly has an Al-Zn alloy intermediate layer material between the core material and the brazing material, and further on the surface of the core material that does not have the intermediate layer material. Since the sacrificial anode material may be selectively clad, it is possible to provide a sacrificial anticorrosive effect on both sides of the tube.

Japanese Unexamined Patent Publication No. 57-073153 JP-A-10-158769

  However, the above-mentioned two aluminum alloy brazing sheets have a problem that preferential corrosion occurs at the joint in the process of use after making the tube of a heat exchanger. For example, the tube shown in FIG. 3 is formed into a cylindrical shape by brazing both ends of a three-layer aluminum alloy brazing sheet made of brazing material / heart material / sacrificial anode material. In this tube, the brazing material melted from the Al—Si alloy that is the brazing material at the time of brazing gathers at the joint and solidifies (hereinafter, the brazing material gathered and solidified at the joint is referred to as “the joint part”). This is called “brazing material”). At this time, since the brazing material contains Zn, concentration of Zn in the final solidified portion is inevitable. As a result, the pitting corrosion potential on the surface of the brazing filler metal at the joint becomes the lowest, and this is a site where corrosion preferentially occurs. Since the inside of the tube in FIG. 3 is filled with cooling water, such preferential corrosion progresses from one end of the joint to the other as shown by arrow D in FIG. In this case, a corroded portion as shown in FIG.

  Moreover, even if it sees about the 4 layer material provided with the intermediate | middle layer material of patent documents 1, 2, it cannot necessarily avoid the preferential corrosion of a junction part. In these brazing sheets, since Zn is added to the intermediate layer material and the sacrificial anode material, Zn is also concentrated by diffusion during brazing addition heat in the joint as shown in FIG. 3, and preferential corrosion occurs. This is because the concern cannot be dispelled. In these patent documents, no consideration is given to preferential corrosion at the joint between the brazing sheets.

  That is, in patent document 1, it shows only 0.3-2.0% about the added Zn amount of an intermediate | middle layer material and a sacrificial anode material, Zn concentrates on the junction part of tube materials, and it is based on it. There is no concern about the preferential corrosion of the joints. Also, regarding Patent Document 2, it is said that only 7072 or the like is used for the sacrificial anode material, and it is clear that no consideration is given to the possibility of preferential corrosion at the joint.

  Furthermore, these patent documents 1 and 2 do not consider the corrosion resistance with respect to the condensed water containing the acidic exhaust gas component mentioned above. For example, the brazing sheets in Patent Documents 1 and 2 are those in which a wide range of concentrations of Mn are added to the intermediate layer. In particular, in Patent Document 2, an intermediate layer containing 0.6% or more of Mn is described in the examples. ing. However, Mn in the intermediate layer forms an intermetallic compound with Si in the adjacent brazing material, and this compound tends to increase the corrosion rate in an acidic environment. In other words, in order to ensure corrosion resistance in an acidic environment, the intermediate layer need not simply contain Zn, and it is necessary to consider the influence of other constituent elements. There is no such consideration.

  As described above, when an aluminum alloy brazing sheet is used as, for example, a tube material for a heat exchanger, both the inner and outer surfaces of the tube are in a corrosive environment, and the sacrificial anticorrosion by the fin is difficult at the joint surface with the fin. It is a conventional technique to provide a sacrificial anti-corrosion effect on both the inner and outer surfaces, and to provide one that has a brazing function on one of the inner and outer surfaces and that does not cause preferential corrosion at the joint between the brazing sheets. It was difficult.

  The present invention has been completed to solve such problems, and presents an aluminum alloy brazing sheet having a sacrificial anticorrosive effect on both sides and having a brazing function on one side. This aluminum alloy brazing sheet prevents preferential corrosion at the brazed joint, and exhibits good brazing properties without diffusion of the molten brazing into the core material during brazing. Moreover, the flow path formation component of the heat exchanger for motor vehicles using this highly corrosion-resistant aluminum alloy brazing sheet is also provided.

  As can be understood from the above-mentioned problems, in order to prevent preferential corrosion at the joint between the aluminum alloy brazing sheets after brazing, it is necessary to consider the corrosion resistance of the joint in the state after brazing. In order to prevent corrosion of the joint, the relationship between the sacrificial anode material surface after brazing and the brazing material surface of the joint, and the relationship between the brazing material layer surface after brazing and the core material are appropriate. It is necessary to have a pitting corrosion potential relationship.

  As a result of intensive studies, the present inventors clad an intermediate layer material containing Zn between the core material and the brazing material, and clad a sacrificial anode material containing Zn on the surface of the core material without the intermediate layer. Furthermore, it was considered that the above-described preferable pitting corrosion potential relationship can be achieved by appropriately maintaining the relationship between the Zn content and thickness of the intermediate layer material and the Zn content and thickness of the sacrificial anode material. The present inventors have found that a material clad with a brazing material, an intermediate layer material, a core material, and a sacrificial anode material each having a specific alloy composition can solve the problems of the present application, and complete the present invention. It came to.

  The present invention that solves the above-described problems includes a core material, an intermediate layer material clad on one surface of the core material, a brazing material clad on the intermediate material, and a sacrificial anode clad on the other surface of the core material. In the highly corrosion-resistant aluminum alloy brazing sheet comprising the material, the core material includes Si: 0.05 to 1.5 mass%, Fe: 0.05 to 2.0 mass%, Mn: 0.5 to 2.0 mass%. The intermediate layer material contains Zn: 0.5-8.0 mass%, Si: 0.05-1.5 mass%, Fe: 0.05- It consists of an aluminum alloy containing 2.0 mass%, the balance being Al and unavoidable impurities, and the brazing material is made of Si: 2.5-13.0 mass%, Fe: 0.05-1.2 ma. The sacrificial anode material contains Zn: 0.5 to 8.0 mass%, Si: 0.05 to 1.5 mass%, Fe: 0. 0.05 to 2.0 mass%, consisting of the balance Al and inevitable impurities, and the value of Zn addition amount (%) × thickness (μm) in the sacrificial anode material is Zn addition in the intermediate layer material It is a highly corrosion-resistant aluminum alloy brazing sheet characterized by being not less than the amount (%) × thickness (μm) value.

  Hereinafter, preferred embodiments of the highly corrosion-resistant aluminum alloy brazing sheet and the method for producing the same according to the present invention will be described in detail. First, each structure of the core material, the intermediate layer material, the brazing material, and the sacrificial anode material constituting the highly corrosion resistant aluminum alloy brazing sheet according to the present invention will be described, and further, the Zn amount and thickness of the intermediate layer material and the sacrificial anode material The relationship will be described. In the following description, “%” indicating the material composition means mass%.

A. The core material contains Si: 0.05 to 1.5%, Fe: 0.05 to 2.0%, Mn: 0.5 to 2.0% as essential elements, and the balance Al and inevitable impurities An aluminum alloy is used. As the aluminum alloy used for the core material of the present invention, a JIS 3000 series alloy, for example, an Al-Mn series alloy such as a JIS 3003 alloy is preferably used. Hereinafter, each component will be described.

  Si forms an Al-Fe-Mn-Si intermetallic compound together with Fe and Mn, and improves the strength by dispersion strengthening, or improves the strength by solid solution strengthening by solid solution in the aluminum matrix. It is an essential constituent element. Si content is 0.05 to 1.5%. If it is less than 0.05%, the above effect is insufficient, and if it exceeds 1.5%, the melting point of the core material is lowered and the possibility of melting is increased. A preferable content of Si is 0.1 to 1.2%.

  Fe is an essential constituent element that forms an Al—Fe—Mn—Si intermetallic compound together with Si and Mn, and improves the strength by dispersion strengthening. The addition amount of Fe is 0.05 to 2.0%. If the content is less than 0.05%, high-purity aluminum ingots must be used, resulting in high costs. On the other hand, if it exceeds 2.0%, a giant intermetallic compound is likely to be formed during casting, and the plastic workability is lowered. The preferable content of Fe is 0.1 to 1.5% or less.

  Mn is an essential constituent element that forms an Al-Mn-Si-based intermetallic compound with Si and improves strength by dispersion strengthening, or solid solution in an aluminum matrix to improve strength by solid solution strengthening It is. Mn content is 0.5 to 2.0%. If the content is less than 0.5%, the above effect is insufficient. If the content exceeds 2.0%, a giant intermetallic compound is easily formed during casting, and the plastic workability is lowered. A preferable content of Mn is 0.8 to 1.8%.

  Further, the core material is Cu: 0.05 to 1.5%, Mg: 0.05 to 0.5%, Ti 0.05 to 0.3%, Zr: 0.05 to 0.3%, Cr: 0 One or more selected from 0.05 to 0.3% and V: 0.05 to 0.3% may be contained as a selective additive element.

  Cu is an additive element that may be contained because it improves the strength by solid solution strengthening. The Cu content is preferably 0.05 to 1.5%. If it is less than 0.05%, the above effect is insufficient, and if it exceeds 1.5%, there is a high risk of cracking of the aluminum alloy during casting. A preferable content of Cu is 0.3 to 1.0%.

Mg may be contained because it improves the strength by precipitation of Mg ₂ Si. The Mg content is preferably 0.05 to 0.5%. If it is less than 0.05%, the above effect is insufficient, and if it exceeds 0.5%, brazing becomes difficult. The Mg content is more preferably 0.1 to 0.4%.

  Ti is an additive element that may be contained because it improves the strength by solid solution strengthening. The Ti content is preferably 0.05 to 0.3%. If it is less than 0.05%, the above effect is insufficient. If it exceeds 0.3%, it becomes easy to form a giant intermetallic compound, and the plastic workability is lowered. The Ti content is more preferably 0.1 to 0.2%.

  Zr is an additive element that may be contained because it has the effect of improving strength by solid solution strengthening and precipitating Al—Zr-based intermetallic compounds to coarsen the crystal grains after brazing. The Zr content is preferably 0.05 to 0.3%. If it is less than 0.05%, the above effect cannot be obtained. If it exceeds 0.3%, it becomes easy to form a giant intermetallic compound, and the plastic workability is lowered. The Zr content is more preferably 0.1 to 0.2%.

  Cr is an additive element that may be included because it has the effect of improving the strength by solid solution strengthening and precipitating Al—Cr intermetallic compounds to coarsen the crystal grains after brazing. The Cr content is preferably 0.05 to 0.3%. If it is less than 0.05%, the above effect cannot be obtained. If it exceeds 0.3%, it becomes easy to form a giant intermetallic compound, and the plastic workability is lowered. The Cr content is more preferably 0.1 to 0.2%.

  V is an additive element that may be contained because it improves the strength and improves the corrosion resistance by solid solution strengthening. The V content is preferably 0.05 to 0.3%. If it is less than 0.05%, the above effect cannot be obtained. If it exceeds 0.3%, it becomes easy to form a giant intermetallic compound, and the plastic workability is lowered. The V content is more preferably 0.1 to 0.2%.

  These selective additive elements such as Cu, Mg, Ti, Zr, Cr, and V may be added to the core material if necessary. Furthermore, in addition to the above essential elements and selective additive elements, unavoidable impurities may be contained in amounts of 0.05% or less, respectively, and 0.15% in total.

B. Intermediate layer material The intermediate layer material contains Zn: 0.5-8.0%, Si: 0.05-1.5%, Fe: 0.05-2.0% as essential elements, and the balance Al In addition, an aluminum alloy made of inevitable impurities is used.

  Zn diffuses to the surface of the brazing material during the heat of brazing, and can reduce the pitting corrosion potential on the surface of the brazing material after the brazing heat. By forming a potential difference between the brazing material surface and the core material, the sacrificial anode effect Thus, the corrosion resistance can be improved. The Zn content is 0.5 to 8.0%. If it is less than 0.5%, the effect of improving the corrosion resistance due to the sacrificial anode effect cannot be sufficiently obtained. On the other hand, if it exceeds 8.0%, the corrosion rate increases, the sacrificial anticorrosion layer disappears early, and the corrosion resistance decreases. The preferable content of Zn is 1.0 to 6.0%.

  Si forms an Al-Fe-Si-based intermetallic compound with Fe, and when it simultaneously contains Mn, forms an Al-Fe-Mn-Si-based intermetallic compound with Fe and Mn, The strength is improved by dispersion strengthening, or the solid strength is improved by solid solution strengthening in the aluminum matrix. The Si content is 0.05 to 1.5%. If the content is less than 0.05%, high-purity aluminum ingots must be used, resulting in high costs. On the other hand, if it exceeds 1.5%, the melting point of the intermediate layer material is lowered and the possibility of melting during brazing increases. A preferable content of Si is 0.1 to 1.2%.

  Fe forms an Al—Fe—Si based intermetallic compound with Si, and when it contains Mn at the same time, forms an Al—Fe—Mn—Si based intermetallic compound with Si and Mn, Strength is improved by dispersion strengthening. The addition amount of Fe is 0.05 to 2.0%. If the content is less than 0.05%, high-purity aluminum ingots must be used, resulting in high costs. On the other hand, if it exceeds 2.0%, a giant intermetallic compound is likely to be formed during casting, and the plastic workability is lowered. The preferable content of Fe is 0.1 to 1.5% or less.

  Further, the intermediate layer material is Mn: 0.05 to 0.5%, Mg: 0.05 to 0.5%, Ti: 0.05 to 0.3%, Zr: 0.05 to 0.3% One or more selected from Cr: 0.05 to 0.3 mass% and V: 0.05 to 0.3 mass% may be further contained as a selective additive element.

  Mn forms an Al—Fe—Mn—Si intermetallic compound together with Si and Fe. While this intermetallic compound improves strength by dispersion strengthening, this intermetallic compound also increases the corrosion rate. In particular, since the intermediate layer material is adjacent to the brazing material, it is easy to form an Al—Fe—Mn—Si-based intermetallic compound. Therefore, the content of Mn needs to be within an appropriate range. The Mn content is preferably 0.5% or less. If it exceeds 0.5%, the corrosion rate increases due to the influence of the intermetallic compound, the sacrificial anticorrosion layer disappears early, and the corrosion resistance decreases. On the other hand, if it is less than 0.05%, the effect of improving the strength is not sufficient. In this regard, in the above-mentioned Patent Document 2, there is an application example of an intermediate layer material to which 0.6% or more of Mn is added as an example, and that this prior art does not consider the corrosion rate in an acidic environment. it is obvious.

  In view of corrosion resistance, the Mn content is more preferably regulated to 0.1% or less, and still more preferably 0.01% or less. Moreover, although there is no lower limit to the preferable content of Mn from the viewpoint of corrosion resistance, if the content is less than 0.001%, high-purity aluminum ingots must be used, resulting in high costs.

Mg is an additive element that may be contained because it improves the strength by precipitation of Mg ₂ Si. The Mg content is preferably 0.05 to 0.5%. If it is less than 0.05%, the above effect is insufficient, and if it exceeds 0.5%, brazing becomes difficult. The Mg content is more preferably 0.1 to 0.4%.

  Ti is an additive element that may be contained because it improves strength and improves corrosion resistance by solid solution strengthening. The Ti content is preferably 0.05 to 0.3%. If it is less than 0.05%, the above effect cannot be obtained. If it exceeds 0.3%, it becomes easy to form a giant intermetallic compound, and the plastic workability is lowered. The Ti content is more preferably 0.05 to 0.2%.

  Zr is an additive element that may be contained because it has the effect of improving strength by solid solution strengthening and precipitating Al—Zr-based intermetallic compounds to coarsen the crystal grains after brazing. The Zr content is preferably 0.05 to 0.3%. If it is less than 0.05%, the above effect cannot be obtained. If it exceeds 0.3%, it becomes easy to form a giant intermetallic compound, and the plastic workability is lowered. The Zr content is more preferably 0.1 to 0.2%.

  Cr is an additive element that may be included because it has the effect of improving the strength by solid solution strengthening and precipitating Al—Cr intermetallic compounds to coarsen the crystal grains after brazing. The Cr content is preferably 0.05 to 0.3%. If it is less than 0.05%, the above effect cannot be obtained. If it exceeds 0.3%, it becomes easy to form a giant intermetallic compound, and the plastic workability is lowered. The Cr content is more preferably 0.1 to 0.2%.

  V is an additive element that may be contained because it improves the strength and improves the corrosion resistance by solid solution strengthening. The V content is preferably 0.05 to 0.3%. If it is less than 0.05%, the above effect cannot be obtained. If it exceeds 0.3%, it becomes easy to form a giant intermetallic compound, and the plastic workability is lowered. The V content is more preferably 0.05 to 0.2%.

  These selective additive elements Ti, Zr, Cr, and V may be added in the intermediate layer material if necessary. Furthermore, in addition to the above essential elements and selective additive elements, unavoidable impurities may be contained in amounts of 0.05% or less, respectively, and 0.15% in total.

C. For the brazing material, an aluminum alloy containing Si: 2.5 to 13.0%, Fe: 0.05 to 1.2% as essential elements, and the balance Al and inevitable impurities is used.

  Si is an essential constituent element of the brazing material, and its addition lowers the melting point of the brazing material and produces a liquid phase, thereby enabling brazing. Si content is 2.5 to 13.0%. If it is less than 2.5%, the resulting liquid phase is small and brazing becomes difficult to function. On the other hand, if it exceeds 13.0%, for example, the amount of Si diffusing into the counterpart material such as fins becomes excessive, and the counterpart material melts. The preferable content of Si is 3.5 to 12.0%.

  Fe easily forms an Al—Fe-based or Al—Fe—Si-based intermetallic compound, so that the amount of Si effective for brazing is reduced and brazing properties are reduced. That is, Fe is an element whose concentration should be regulated in order to ensure brazing. Fe content is 0.05 to 1.2%. If it is less than 0.05%, high-purity aluminum ingots must be used, resulting in high costs. On the other hand, if it exceeds 1.0%, brazing becomes insufficient due to the above action. A preferable content of Fe is 0.1 to 0.5%.

In the present invention, the brazing material is Cu: 0.05 to 0.6 %, Mn: 0.05 to 2.0%, Ti: 0.05 to 0.3%, Zr: 0.05 to 0 .3%, Cr: 0.05-0.3%, V: 0.05-0.3%, Na: 0.001-0.05%, Sr: 0.001-0.05% One or more of these may be further contained as a selective additive element.

Cu is an additive element that may be contained because it improves the strength by solid solution strengthening. The Cu content is preferably 0.05 to 0.6 %. If the content is less than 0.05%, the above effect is insufficient. On the other hand, if the content exceeds 0.6%, the surface pitting corrosion potential becomes noble, the sacrificial anticorrosion effect is lost, and the corrosion resistance decreases. A more preferable content of Cu is 0.1 to 0.4%.

  Mn is an additive element that may be contained because it improves strength and corrosion resistance. The Mn content is preferably 0.05 to 2.0%. If it exceeds 2.0%, a giant intermetallic compound is likely to be formed during casting, and the plastic workability is lowered. On the other hand, if it is less than 0.05%, the effect cannot be sufficiently obtained. The Mn content is more preferably 0.05 to 1.8%.

  Ti is an additive element that may be contained because it improves strength and improves corrosion resistance by solid solution strengthening. The Ti content is preferably 0.05 to 0.3%. If it is less than 0.05%, the above effect cannot be obtained. If it exceeds 0.3%, it becomes easy to form a giant intermetallic compound, and the plastic workability is lowered. The Ti content is more preferably 0.1 to 0.2%.

  Zr is an additive element that may be contained because it has the effect of improving strength by solid solution strengthening and precipitating Al—Zr-based intermetallic compounds to coarsen the crystal grains after brazing. The Zr content is preferably 0.05 to 0.3%. If it is less than 0.05%, the above effect cannot be obtained. If it exceeds 0.3%, it becomes easy to form a giant intermetallic compound, and the plastic workability is lowered. The Zr content is more preferably 0.1 to 0.2%.

  Cr has a function of improving strength by solid solution strengthening and precipitating an Al—Cr intermetallic compound to coarsen crystal grains after brazing, so Cr may be contained. The Cr content is preferably 0.05 to 0.3%. If it is less than 0.05%, the above effect cannot be obtained. If it exceeds 0.3%, it becomes easy to form a giant intermetallic compound, and the plastic workability is lowered. The Cr content is more preferably 0.1 to 0.2%.

  V may be contained because it improves the strength and improves the corrosion resistance by solid solution strengthening. V content is 0.05 to 0.3%. If it is less than 0.05%, the above effect cannot be obtained. If it exceeds 0.3%, it becomes easy to form a giant intermetallic compound, and the plastic workability is lowered. The V content is preferably 0.1 to 0.2%.

  At least one of Mn, Ti, Zr, Cr, and V, which are the above selective additive elements, may be added to the brazing material as necessary. Further, in addition to the essential elements and the selective additive elements, unavoidable impurities may be contained in amounts of 0.05% or less, respectively, and 0.15% in total.

D. Sacrificial anode material The sacrificial anode material contains Zn: 0.5-8.0%, Si: 0.05-1.5%, Fe: 0.05-2.0% as essential elements, and the balance Al In addition, an aluminum alloy made of inevitable impurities is used.

  Zn can lower the pitting corrosion potential, and can improve the corrosion resistance by the sacrificial anode effect by forming a potential difference with the core material. The Zn content is 0.5 to 8.0%. If it is less than 0.5%, the effect of improving the corrosion resistance due to the sacrificial anode effect cannot be sufficiently obtained. On the other hand, if it exceeds 8.0%, the corrosion rate increases, the sacrificial anticorrosion layer disappears early, and the corrosion resistance decreases. The preferable content of Zn is 2.1 to 6.0%.

  Si forms an Al-Fe-Si-based intermetallic compound with Fe, and when it simultaneously contains Mn, forms an Al-Fe-Mn-Si-based intermetallic compound with Fe and Mn, The strength is improved by dispersion strengthening, or the solid strength is improved by solid solution strengthening in the aluminum matrix. The Si content is 0.05 to 1.5%. If the content is less than 0.05%, high-purity aluminum ingots must be used, resulting in high costs. On the other hand, if it exceeds 1.5%, the possibility of melting during brazing increases. A preferable content of Si is 0.1 to 1.2%.

  Fe forms an Al—Fe—Si based intermetallic compound with Si, and when it contains Mn at the same time, forms an Al—Fe—Mn—Si based intermetallic compound with Si and Mn, Strength is improved by dispersion strengthening. The addition amount of Fe is 0.05 to 2.0%. If the content is less than 0.05%, high-purity aluminum ingots must be used, resulting in high costs. On the other hand, if it exceeds 2.0%, a giant intermetallic compound is likely to be formed during casting, and the plastic workability is lowered. The preferable content of Fe is 0.1 to 1.5% or less.

  The sacrificial anode material is Mg: 0.05-3.0%, Mn: 0.05-2.0%, Ti: 0.05-0.3%, Zr: 0.05-0.3% One or more selected from Cr: 0.05 to 0.3 mass% and V: 0.05 to 0.3 mass% may be further contained as a selective additive element.

Mg improves the strength of the sacrificial anode material by precipitation of Mg ₂ Si. In addition to improving the strength of the sacrificial anode material itself, brazing causes Mg to diffuse from the sacrificial anode material to the core material, thereby improving the strength of the core material. For these reasons, Mg may be included. The content of Mg is preferably 0.05 to 3.0%. If it is less than 0.05%, these effects may not be sufficiently obtained, and if it exceeds 3.0%, it becomes difficult to press the sacrificial anode material and the core material in the clad hot rolling process. The Mg content is more preferably 0.1 to 2.0%. In addition, since Mg deteriorates the flux in Nocolok brazing and inhibits brazeability, when the sacrificial anode material contains 0.5% or more Mg, Nocolok brazing cannot be used for joining the tube materials. . In this case, it is necessary to use means such as welding for joining the tube materials, for example.

  Mn may be contained because it improves strength and corrosion resistance. The Mn content is 0.05 to 2.0%. If it exceeds 2.0%, a giant intermetallic compound is likely to be formed at the time of casting, so that the plastic workability is lowered and the potential of the sacrificial anode layer is made noble, so that the sacrificial anode effect is inhibited and the corrosion resistance is lowered. On the other hand, if it is less than 0.05%, the effect cannot be sufficiently obtained. The Mn content is preferably 0.05 to 1.8%.

  Ti may be contained because it improves strength by solid solution strengthening and also improves corrosion resistance. Ti content is 0.05 to 0.3%. If it is less than 0.05%, the above effect cannot be obtained. If it exceeds 0.3%, it becomes easy to form a giant intermetallic compound, and the plastic workability is lowered. The Ti content is preferably 0.05 to 0.2%.

  Zr may be contained because it has the effect of improving strength by solid solution strengthening and precipitating Al—Zr-based intermetallic compounds to coarsen the crystal grains after brazing. The Zr content is 0.05 to 0.3%. If it is less than 0.05%, the above effect cannot be obtained. If it exceeds 0.3%, it becomes easy to form a giant intermetallic compound, and the plastic workability is lowered. The Zr content is preferably 0.1 to 0.2%.

  Cr has a function of improving strength by solid solution strengthening and precipitating an Al—Cr intermetallic compound to coarsen crystal grains after brazing, so Cr may be contained. The Cr content is 0.05 to 0.3%. If it is less than 0.05%, the above effect cannot be obtained. If it exceeds 0.3%, it becomes easy to form a giant intermetallic compound, and the plastic workability is lowered. The Cr content is preferably 0.1 to 0.2%.

  V may be contained because it improves the strength and improves the corrosion resistance by solid solution strengthening. V content is 0.05 to 0.3%. If it is less than 0.05%, the above effect cannot be obtained. If it exceeds 0.3%, it becomes easy to form a giant intermetallic compound, and the plastic workability is lowered. The V content is preferably 0.05 to 0.2%.

  These Mn, Ti, Zr, Cr, and V may be added in the intermediate layer material if necessary. Furthermore, in addition to the above essential elements and selective additive elements, unavoidable impurities may be contained in amounts of 0.05% or less, respectively, and 0.15% in total.

  The aluminum alloy brazing sheet clad with the core material, the intermediate layer material, the brazing material, and the sacrificial anode material having the appropriate composition described above is subjected to brazing additional heat when formed into a tube as shown in FIG. 3, for example. Thus, the joint is filled with the molten solder, and the solder is solidified by the subsequent cooling.

  Here, in the tube after brazing, if there is a base portion with a pitting potential lower than the surroundings, the portion preferentially corrodes. In such a state after brazing, if the pitting corrosion potential on the surface of the sacrificial anode material is the same as or lower than the pitting corrosion potential on the surface of the brazing filler metal surface, the surface of the sacrificial anode material is preferentially corroded. Preferential corrosion of the part does not occur.

  On the other hand, the brazing material after brazing needs to have a so-called sacrificial anode effect that preferentially corrodes the brazing material surface over the core material. When the pitting corrosion potential difference between the brazing filler metal surface and the core material after brazing is 20 mV or more, the sacrificial anode effect due to this potential difference is exerted, so that the generation of through holes due to corrosion from the brazing filler metal side can be prevented. If the pitting corrosion potential difference between the brazing filler metal surface and the core material after brazing is less than 20 mV, the sacrificial anode effect due to this potential difference is not sufficient, and through holes are generated due to corrosion from the brazing filler metal side. Here, the pitting corrosion potential difference between the brazing material surface and the core material after brazing is defined as a value obtained by subtracting the pitting corrosion potential of the brazing material surface from the pitting corrosion potential of the core material after brazing.

  Therefore, the brazing sheet according to the present invention is suitable for the relationship between the pitting corrosion potential on the surface of the sacrificial anode material after brazing and the pitting corrosion potential on the surface of the brazing material at the joint portion. Is made larger than the total amount of Zn contained in the intermediate layer material. The total amount of Zn in the sacrificial anode material and the intermediate layer material is calculated by Zn addition amount (%) × thickness (μm). In the present invention, the value of Zn addition amount (%) × thickness (μm) in the sacrificial anode material is not less than the value of Zn addition amount (%) × thickness (μm) in the intermediate layer material, The pitting corrosion potential on the surface of the sacrificial anode material is set equal to or lower than the pitting corrosion potential on the surface of the brazing filler metal surface.

  In addition, regarding the pitting corrosion potential difference between the brazing material surface after brazing and the core material, as described above, the intermediate layer material Zn diffuses into the brazing material during brazing addition heat, so that the brazing material surface after brazing The pitting corrosion potential can be made lower. In the present invention, by setting the Zn content of the intermediate layer material to 0.5% or more, a potential difference of 20 mV or more is generated with respect to the core material.

  The brazing conditions in the present invention are not particularly limited, but are usually carried out by applying a fluoride-based flux and then heating to about 600 ° C. in a nitrogen atmosphere furnace.

  The overall thickness of the highly corrosion-resistant aluminum alloy brazing sheet according to the present invention is not particularly limited. For example, when used as a tube material for a heat exchanger for automobiles, a thin brazing sheet of about 0.6 mm or less is usually used. can do. However, it is not limited to the plate thickness within this range, and it can be used as a relatively thick material of about 0.6 mm or more and about 5 mm or less.

  Further, the individual cladding rates of the brazing material layer, the intermediate layer material, and the sacrificial anode material layer are usually about 2 to 30%. For the sacrificial anode material and the intermediate layer material, the clad rate can be set by defining the thickness in consideration of the respective Zn amounts.

  The highly corrosion-resistant aluminum alloy brazing sheet according to the present invention described above is suitable for manufacturing a flow path forming component of an automobile heat exchanger, that is, a tube. For example, a brazing sheet as shown in FIG. 1 woven into a B-shaped cross section is brazed by applying a flux and heating to about 600 ° C.

  When the highly corrosion-resistant aluminum alloy brazing sheet according to the present invention is used as a flow path forming component of a heat exchanger for automobiles, one surface forms a flow path for cooling liquid, and the other surface is in contact with air. The above effect is maximized when condensed water having a total solute concentration of 1000 ppm or less and containing 5 ppm or more of chloride ions and having a pH of 4 or less is formed on the surface of the other surface. To be demonstrated.

  That is, in such a corrosive environment, sacrificial corrosion is necessary because the condensate has pitting corrosion-inducing properties, but sacrificial corrosion by fins does not work effectively because the solute concentration is low and it is not a submerged environment. . The high corrosion resistance aluminum alloy brazing sheet according to the present invention is also useful for such a corrosive environment. When the chloride ion concentration of the condensate is 500 ppm or less and the total value of the solute concentrations is 10000 ppm or less, the sacrificial corrosion prevention by the fins is not effectively exhibited, so that the effect of the present invention becomes more effective. Even when the solute concentration of the condensate is 10000 ppm or less, if the opposite surface is not a corrosive environment such as cooling water, the possibility of preferential corrosion of the tube joint is low. Further, when the chloride ion concentration of the condensate is 5 ppm or more, the condensed water has pitting corrosion-inducing properties, so that the effect of the present invention becomes more effective. Further, when the pH of the condensed water is 4 or less, the corrosion rate due to the condensed water is very high, so that the effect of the present invention becomes more effective.

  The manufacturing process of the highly corrosion-resistant aluminum alloy brazing sheet of the present invention includes a casting process in which the aluminum alloy core material, the intermediate layer material, the sacrificial anode material, and the Al—Si alloy brazing material are respectively cast into an ingot; A hot rolling process in which the sacrificial anode material, the intermediate layer material and the Al—Si alloy brazing material are each hot-rolled; and the hot-rolled sacrificial anode material is superposed on one surface of the ingot for the core material and hot rolled A hot clad rolling process in which the Al—Si based alloy brazing material is superposed on the other surface of the ingot for the core material, and these are heated and hot rolled to form a clad material; A cold rolling step for cold rolling; and an annealing step for performing annealing in the middle of cold rolling or after cold rolling.

  There are no particular restrictions on the conditions in the casting process, but it is usually carried out by water-cooled semi-continuous casting. In the hot rolling process and the hot cladding rolling process, the heating temperature is usually preferably about 400 to 560 ° C. If it is less than 400 ° C, the plastic workability is poor, and cracks may occur during rolling. In the case of hot clad rolling, it is difficult to press the brazing material, intermediate layer material, and sacrificial anode material against the core material. In some cases, hot rolling cannot be performed. On the other hand, when the temperature is higher than 560 ° C., the brazing filler metal may be melted during heating.

  The annealing step is usually preferably performed at about 100 to 560 ° C. for the purpose of reducing processing strain during rolling. If it is less than 100 degreeC, the effect may not be enough, and when it exceeds 560 degreeC, there exists a possibility that a brazing material may fuse | melt. Note that a batch type furnace or a continuous type furnace may be used for the annealing step. Moreover, although an annealing process is performed at least 1 time or more in the middle of a cold rolling process or after a cold rolling process, there is no upper limit in the frequency | count of implementation.

  The ingot obtained by casting the aluminum alloy core may be subjected to a homogenization treatment step before the hot clad rolling step. The homogenization treatment step is usually preferably performed at 450 to 620 ° C. If the temperature is lower than 450 ° C., the effect may not be sufficient, and if it exceeds 620 ° C., the core material ingot may be melted.

  The aluminum alloy brazing sheet according to the present invention has, for example, a tube material for a heat exchanger, and has an effective anticorrosion performance even when the inside and outside of the tube are in a severe corrosive environment. Moreover, the brazing function is also given to the single side | surface. And the preferential corrosion in the junction part when brazing sheets are brazed and joined for shaping | molding of a tube is also suppressed. The aluminum alloy brazing sheet according to the present invention is excellent in brazing properties such as fin joint rate and erosion resistance, and is suitably used as a heat exchanger tube material for automobiles from the viewpoint of light weight and good thermal conductivity. It is done.

It is sectional drawing of the tube shape | molded by the B type cross-sectional shape which consists of an aluminum alloy brazing sheet. It is a schematic diagram which shows the sample for a measurement of the pitting corrosion potential of the highly corrosion-resistant aluminum alloy brazing sheet and the corrosion test on the sacrificial material side according to the present invention. It is explanatory drawing which shows the preferential corrosion of the tube which consists of a 3 layer aluminum alloy brazing sheet.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail based on examples and comparative examples. In this embodiment, a brazing material having an alloy composition shown in Table 1, an intermediate layer material having an alloy composition shown in Table 2, a core material having an alloy composition shown in Table 3, and a sacrificial anode material having an alloy composition shown in Table 4 are used. After each manufacture, it clad and made the aluminum alloy brazing sheet.

  Each alloy was cast by DC casting and finished by facing each side. The thickness of the ingot after chamfering was 400 mm in all cases. For the brazing material, the intermediate layer material, and the sacrificial anode material, calculate the cladding ratio that will be the target thickness by the final plate thickness, and in the heating process at 520 ° C. for 3 hours so as to obtain the required thickness at the time of matching. After being provided, it was hot-rolled to a predetermined thickness.

  Using these alloys, the intermediate material of Table 2 is combined on one side of the core material alloy, the sacrificial anode material of Table 4 is combined on the other surface, and the brazing alloy of Table 1 is used for the intermediate material. Combined. In some cases, the intermediate layer material was not used, and the brazing material shown in Table 1 was combined on one side of the core alloy and the sacrificial anode material shown in Table 4 was combined on the other side. These laminated materials were subjected to a heating process at 520 ° C. for 3 hours, and then subjected to a hot cladding rolling process to produce a 4-layer or 3-layer cladding material having a thickness of 3.5 mm. The four-layer or three-layer clad material was subjected to cold rolling, intermediate annealing held at 400 ° C. for 5 hours, and final cold rolling to prepare a H1n tempered brazing sheet sample. The cold rolling rate after the intermediate annealing was 40% in all cases.

  Table 5 shows the thickness of each layer in the combination of the core material, brazing material, intermediate layer material, sacrificial anode material, final plate thickness, and final plate thickness for the brazing sheets of the examples and comparative examples in the present embodiment. Show. Table 5 also shows the value of Zn amount (%) × thickness (μm) of the sacrificial anode material.

  In the above manufacturing process, the evaluation of the productivity of the brazing sheet was also performed. If no problems occur in this manufacturing process and rolling to a final sheet thickness of 0.3 mm is possible, the productivity is set to “◯”, and cracking occurs during casting or rolling, and rolling can be performed to a final sheet thickness of 0.3 mm. If not, the manufacturability was evaluated as “x”. The manufacturability evaluation results are also shown in Table 5.

  And about the brazing sheet sample of the manufactured Example and Comparative Example, brazing property, tensile strength after brazing, sacrificial anode material surface Zn amount after brazing, brazing material side corrosion resistance, sacrificial material by the following methods Evaluation and measurement of side corrosion resistance were performed.

(Evaluation of brazing)
A fin material having a thickness of 0.07 mm, a tempered H14, and a composition in which 1.0% Zn was added to 3003 alloy was prepared, and this was corrugated to obtain a heat exchanger fin material. The fin material was placed on the brazing material surface of the brazing sheet sample, immersed in a 5% fluoride flux aqueous solution, and subjected to brazing addition heat at 600 ° C. for 3 minutes to prepare a minicore sample. When the fin joint rate of this mini-core sample is 95% or more, and the brazing sheet sample and the fin are not melted, the brazing property is “good”, and the fin joint rate is less than 95%. When melting occurred in the brazing sheet sample, the brazing property was determined as “x” when the case corresponding to at least one of the cases where melting occurred in the fin.

(Measurement of tensile strength after brazing)
A brazing sheet sample subjected to heat treatment at 600 ° C. for 3 minutes (corresponding to brazing addition heat) was subjected to a tensile test according to JIS Z2241 under the conditions of a tensile speed of 10 mm / min and a gauge length of 50 mm. The tensile strength was read from the obtained stress-strain curve. As a result, the case where the tensile strength was 120 MPa or more was determined to be a pass “◯”, and the case where the tensile strength was less than “MP”.

(Measurement of pitting corrosion potential)
The brazing material surface and sacrificial anode material surface of the brazing sheet sample were overlapped as shown in FIG. 2, and 5% fluoride flux aqueous solution was applied to the overlapping portion and dried. Next, the entire dried brazing sheet sample was covered with stainless steel foil, and this was subjected to brazing addition heat at 600 ° C. for 3 minutes to prepare a combined sample. NaCl was dissolved in pure water to give a 5 wt% NaCl aqueous solution, and an aqueous solution adjusted to pH 3 by adding acetic acid was prepared.

  The combined sample was immersed in this aqueous solution, and polarization was measured by scanning the potential from −1500 to 0 mV using a potentiostat while bubbling with nitrogen gas. The measurement target portions were the brazing filler metal surface, the sacrificial anode material surface, the brazing filler metal surface of the joint, and the core material surface. Masking was performed using an insulating resin so that only the measurement target portion was exposed in each measurement. In the measurement of the core material, the measurement was performed by immersing the core material in the NaOH solution to expose the core material. The pitting corrosion potential was read from the anodic polarization curve thus obtained, and the pitting corrosion potential on the surface of the sacrificial anode material, the pitting corrosion potential on the joint surface, and the pitting corrosion potential difference between the core material and the brazing material surface were calculated. The pitting corrosion potential difference between the core material and the brazing material surface is a value obtained by subtracting the pitting corrosion potential on the brazing material surface from the pitting corrosion potential of the core material.

(Evaluation of brazing material side corrosion resistance)
Using the same mini-core sample as used in the evaluation of brazing, masking the sacrificial anode material surface of the brazing sheet with an insulating resin and using the brazing material surface as a test surface, 500 hours and 1000 hours based on JIS-H8502 Were subjected to CASS test. As a result, the case where corrosion penetration did not occur in the brazing sheet after 1000 hours was designated as “PASS” for CASS corrosion resistance, and the case where corrosion penetration did not occur in 500 hours but occurred in 1000 hours was indicated as “△” where corrosion resistance was insufficient. The case where corrosion penetration occurred in 500 hours was defined as a CASS corrosion resistance failure “x”.

  For the corrosion resistance evaluation on the brazing side, in addition to the above CASS test, a corrosion test using an acidic solution shown in Table 5 is also performed. In this corrosion test, a masked mini-core sample was sprayed for 2 hours (spraying amount 1 to 2 ml / 80 cm 2 / h), dried 2 hours (relative humidity 20 to 30%), and wet with a cyclic corrosion tester. The sample was subjected to a cyclic corrosion test for 2 hours (relative humidity of 95% or more). Each spray solution was an aqueous solution of the components shown in Table 5, the temperature in the test tank was 50 ° C., and the test time was 3000 hours. After completion of the test, the corrosion products were removed with concentrated nitric acid, and the depth of the corrosion holes generated on the surface of the sacrificial anode material was measured by the depth of focus method, with the maximum being the corrosion depth. In the evaluation with the aqueous solutions A, B, C, D, and E, the case where the corrosion depth was less than 150 μm was determined as pass (◯), and the case where the corrosion depth was 150 μm or more was determined as reject (×). .

(Evaluation of sacrificial material side corrosion resistance)
The brazing material side of the sample for measuring Zn content was masked with an insulating resin, and the sacrificial anode material surface was used as a test surface. This combined sample was immersed in 88 ° C. high-temperature water containing Cl ⁻ 500 ppm, SO ₄ ²⁻¹⁰⁰ ppm, Cu ²⁺ 10 ppm for 8 hours, and then allowed to stand at room temperature for 16 hours. Served for months and 6 months. As a result, the case where corrosion penetration did not occur in 3 months was evaluated as “O” for the general part, and the case where corrosion penetration occurred in 3 months was determined as “X” for the general part. As for the bonded portion, the case where the peeled portion of the bonded portion did not occur was regarded as acceptable corrosion resistance of the bonded portion (◯), and the case where the peeled portion of the bonded portion caused by corrosion was regarded as rejected corrosion resistance (×).

  The above evaluation results are shown in Table 6. In addition, about the thing of manufacturability "x", since the sample could not be manufactured, these evaluations were not performed. In addition, in the brazeability evaluation, those with an evaluation of “x” described later have items that cannot be evaluated, so other evaluations were omitted.

  Here, the measurement result and evaluation result by each test are examined. First, test No. which is an example. As for 1 to 12 and 44 to 48, these are the compositions of the components of the brazing sheet (brazing material, intermediate layer material, core material, sacrificial anode material) and the relationship between the total amount of Zn in the sacrificial anode material and the intermediate layer material. In this case, the conditions specified in the present invention were satisfied, and all of manufacturability, brazing property, tensile strength after brazing, and corrosion resistance were acceptable. On the other hand, test No. which is a comparative example. Nos. 13 to 43 and 49 to 54 are preferable in any one of manufacturability, brazing, tensile strength after brazing, and corrosion resistance because they do not satisfy the conditions defined in the present invention for each configuration of the brazing sheet. It was not a thing. Specifically, the following results were obtained.

(About the composition of brazing material)
Test No. In No. 13, the brazing property was unacceptable because there was too little Si component in the brazing material.
Test No. In No. 14, the brazing property was rejected because the brazing material contained too much Si component.
Test No. In No. 15, the brazing property was unacceptable because there was too much Fe component in the brazing material.
Test No. In No. 16, since the Cu component of the brazing material was too much, the corrosion resistance on the brazing material side in the liquids D and E was unacceptable.
Test No. In No. 17, since there was too much Mn component of a brazing material, a crack occurred at the time of rolling, a brazing sheet could not be produced, and productivity was unsuccessful.
Test No. In No. 18, since there were too many components of Ti, Zr, Cr, and V in the brazing material, cracking occurred during rolling, and a brazing sheet could not be produced, resulting in an unacceptable productivity.
Test No. In No. 19, the brazing property was rejected because there was too much Na component in the brazing material.
Test No. In No. 20, since there was too much Sr component of a brazing material, brazing property was disqualified.

(About composition of intermediate layer material)
Test No. In No. 21, the brazing property was rejected because the Si component of the intermediate layer material was too much.
Test No. In No. 22, since there were too many Fe components of the intermediate layer material, cracking occurred during rolling, and a brazing sheet could not be produced, resulting in rejected productivity.
Test No. In No. 23, since there were too many Ti, Zr, Cr, and V components of the intermediate layer material, cracking occurred during rolling, and a brazing sheet could not be produced, resulting in an unacceptable productivity.
Test No. In No. 24, since the Mn component of the intermediate layer material was too much, the corrosion resistance on the brazing filler metal side in the liquids D and E was unacceptable.
Test No. In No. 25, since the Zn component in the intermediate layer material was too small, the corrosion resistance on the brazing filler metal side in the liquids D and E was unacceptable.
Test No. In No. 26, since there was too much Zn component in the intermediate layer material, the corrosion resistance on the brazing filler metal side in the liquids D and E failed.
Test No. In No. 27, the brazing property was rejected because the Mg component of the intermediate layer material was too much.
Test No. In 28-30, since it did not have an intermediate | middle layer material, the corrosion resistance in the brazing material side in the liquids D and E was disqualified.

(About the composition of heartwood)
Test No. In No. 31, the brazing property was unacceptable because the Si component of the core material was too much.
Test No. In No. 32, since there was too much Mg component of a core material, brazing property was disqualified.
Test No. In No. 33, since there was too much Fe component of a core material, a crack generate | occur | produced at the time of rolling, and a brazing sheet could not be produced but productivity was disqualified.
Test No. In No. 34, since there were too many Ti, Zr, Cr, and V components of the core material, cracks occurred during rolling, and a brazing sheet could not be produced, resulting in an unacceptable productivity.
Test No. In No. 35, since there was too much Mn component of a core material, a crack generate | occur | produced at the time of rolling, and a brazing sheet could not be produced but productivity was disqualified.
Test No. In No. 36, since there was too much Cu component of a core material, a crack generate | occur | produced at the time of casting, and a brazing sheet could not be produced but productivity was disqualified.
Test No. In No. 37, since the Mn component of the core material was too small, the tensile strength after brazing heat was not acceptable.

(About composition of sacrificial anode material)
Test No. In No. 38, the sacrificial anode material failed in brazing because there was too much Si component.
Test No. In No. 39, since there were too many Fe components of a sacrificial anode material, a crack generate | occur | produced at the time of rolling, and a brazing sheet could not be produced but productivity was disqualified.
Test No. In No. 40, since there were too many Ti, Zr, Cr, and V components of a sacrificial anode material, a crack generate | occur | produced at the time of rolling, and a brazing sheet could not be produced but productivity was disqualified.
Test No. In No. 41, since there was too much Mn component of a sacrificial anode material, a crack generate | occur | produced at the time of rolling, and a brazing sheet could not be produced but productivity was disqualified.
Test No. In No. 42, since the Zn component of the sacrificial anode material was too small, the corrosion resistance on the sacrificial anode material side was rejected.
Test No. In No. 43, the corrosion resistance on the sacrificial anode material side was unacceptable because there was too much Zn component in the sacrificial anode material.

(Regarding the total amount of Zn in the sacrificial anode material and intermediate layer material)
Test No. In 49 to 54, the value of Zn addition amount (%) × thickness (μm) in the sacrificial anode material is less than the value of Zn addition amount (%) × thickness (μm) in the intermediate layer material. As a result, the pitting corrosion potential of the joint after brazing was lower than the surface of the sacrificial anode material, and the corrosion resistance of the joint was unacceptable.

  According to the present invention, for example, it is possible to provide an aluminum alloy brazing sheet for a tube material of a heat exchanger in which both inner and outer surfaces of the tube are in a corrosive environment and sacrificial corrosion prevention by the fins is difficult on the joint surface with the fins. Such a highly corrosion-resistant aluminum alloy brazing sheet has a sacrificial anti-corrosion effect on both the inside and outside of the tube, and has a brazing function on one side, and can prevent the occurrence of preferential corrosion between tubes. Yes, excellent in brazing properties such as fin joint ratio and erosion resistance, light weight, and thermal conductivity. Furthermore, a flow path forming component of an automotive heat exchanger using such a high corrosion resistance aluminum alloy brazing sheet is also provided.

Claims (7)

With heartwood,
An intermediate layer material clad on one surface of the core material;
A brazing material clad on the intermediate layer material;
In a high corrosion resistance aluminum alloy brazing sheet comprising a sacrificial anode material clad on the other surface of the core material,
The core material contains Si: 0.05 to 1.5 mass%, Fe: 0.05 to 2.0 mass%, Mn: 0.5 to 1.8 mass%, and the balance aluminum and unavoidable impurities. Made of alloy,
The said intermediate | middle layer material contains Zn: 0.5-8.0mass%, Si: 0.05-1.5mass%, Fe: 0.05-2.0mass%, and consists of remainder Al and an unavoidable impurity. Made of aluminum alloy,
The brazing material contains Si: 2.5-13.0 mass%, Fe: 0.05-1.2 mass%, and consists of an aluminum alloy composed of the balance Al and inevitable impurities,
The sacrificial anode material contains Zn: 0.5-8.0 mass%, Si: 0.05-1.5 mass%, Fe: 0.05-2.0 mass%, and consists of the balance Al and inevitable impurities. ,
Furthermore, the value of the Zn amount in the sacrificial anode material (%) × thickness ([mu] m) is state, and are greater than or equal to the Zn amount in the intermediate layer material (%) × thickness ([mu] m),
The pitting corrosion potential difference between the brazing filler metal surface and the core material after brazing heat addition at 600 ° C. for 3 minutes is 20 mV or more, and the pitting corrosion potential on the sacrificial anode material surface after brazing heating heat at 600 ° C. for 3 minutes is A highly corrosion-resistant aluminum alloy brazing sheet characterized by having the same or lower base than the pitting potential on the surface of the brazing filler metal.   Further, the core material is Cu: 0.05 to 1.5 mass%, Mg: 0.05 to 0.5 mass%, Ti 0.05 to 0.3 mass%, Zr: 0.05 to 0.3 mass%, Cr: 0 The highly corrosion-resistant aluminum alloy brazing sheet according to claim 1, comprising at least one selected from 0.05 to 0.3 mass% and V: 0.05 to 0.3 mass%.   The intermediate layer material further includes Mn: 0.05 to 0.5 mass%, Mg: 0.05 to 0.5 mass%, Ti 0.05 to 0.3 mass%, Zr: 0.05 to 0.3 mass%, Cr The highly corrosion-resistant aluminum alloy brazing sheet according to claim 1 or 2, comprising one or more selected from: 0.05 to 0.3 mass% and V: 0.05 to 0.3 mass%. The brazing material is further Cu: 0.05 to 0.6 mass%, Mn: 0.05 to 2.0 mass%, Ti: 0.05 to 0.3 mass%, Zr: 0.05 to 0.3 mass%. , Cr: 0.05-0.3 mass%, V: 0.05-0.3 mass%, Na: 0.001-0.05 mass%, Sr: 0.001-0.05 mass% The highly corrosion-resistant aluminum alloy brazing sheet according to any one of claims 1 to 3, comprising the above.   The sacrificial anode material further includes Mg: 0.05 to 3.0 mass%, Mn: 0.05 to 2.0 mass%, Ti 0.05 to 0.3 mass%, Zr: 0.05 to 0.3 mass%, Cr The highly corrosion-resistant aluminum alloy according to any one of claims 1 to 4, comprising one or more selected from: 0.05 to 0.3 mass% and V: 0.05 to 0.3 mass%. Brazing sheet. A flow path forming part of a heat exchanger for automobiles manufactured by brazing the highly corrosion-resistant aluminum alloy brazing sheet according to any one of claims 1 to 5. A heat exchanger using the flow path forming component according to claim 6,
The flow path forming component is formed so that one surface thereof forms a flow path for a cooling liquid and the other surface is in contact with air.
A heat exchanger used in an environment in which condensed water having a total solute concentration of 10,000 ppm or less on the other surface and containing chloride ions of 5 ppm to 500 ppm and having a pH of 4 or less is generated. .

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