JP5913853B2 - Aluminum alloy brazing sheet and method for producing the same - Google Patents

Description

  TECHNICAL FIELD The present invention relates to an aluminum alloy brazing sheet used in a heat exchanger for automobiles, and more particularly to a high formability and high corrosion resistance aluminum alloy brazing sheet suitably used as a high temperature compressed air or refrigerant passage component and a method for producing the same. .

  Aluminum alloys are lightweight and have high thermal conductivity, and can be realized with high corrosion resistance by appropriate processing. Therefore, they are used in automotive heat exchangers such as radiators, condensers, evaporators, heaters, and intercoolers. As a tube material for these automotive heat exchangers, an Al—Mn alloy such as 3003 alloy is used as a core material, and an Al—Si alloy brazing material or an Al—Zn alloy sacrificial anode material is provided on one surface. A clad two-layer clad material or a three-layer clad material clad with an Al—Si alloy brazing material on the other surface is used. The heat exchanger is usually joined by combining such clad material and corrugated fins and brazing at a temperature of about 600 ° C.

  In recent years, heat exchangers have been reduced in size and weight. However, in order to maintain high heat dissipation performance even if the heat exchanger is small, it may be required to give the tube a complicated shape. In order to improve the formability of the tube material, it is preferable that the strength of the tube material in the raw material state is as low as possible and the elongation at break is as large as possible. However, if the structure of the tube material in the state of the raw material is made into a completely recrystallized structure, sub-crystal grains remain during brazing heat due to strain applied during molding, and the braze erodes into the core material and brazeability decreases. Resulting in. Even if the state of the material is a processed structure, it is necessary to have low strength and high elongation at break. Therefore, if the degree of processing during cold rolling is reduced, subgrains remain after heat addition of brazing, and the wax is the core material. It will erode and the brazeability will decrease. Therefore, in order to achieve both excellent formability and brazability, it is necessary to control the metal structure of the core material by devising the manufacturing process.

A technique as described in Patent Document 1 is known as a proposal of a brazing sheet that suppresses the erosion of wax during brazing addition heat. In this technique, as the metal structure of the core material, the number of precipitates having a maximum length of 1 μm or less is 5 × 10 ⁴ pieces / mm ² or less. It is said that wax erosion due to grains can be suppressed. However, no consideration is given to the suppression of wax erosion due to residual subgrains. Moreover, it does not describe a metal structure for reducing the strength of the material.

  As a proposal of a brazing sheet that suppresses erosion of wax by residual sub-crystal grains during brazing addition heat, a technique as described in Patent Document 2 is known. In this technique, homogenization of the core material is performed at 500 to 620 ° C., and the precipitates are coarsened by defining the final annealing conditions in detail, thereby preventing the sub-crystal grains from remaining during the brazing heat. Yes. However, only the temperature is described as the conditions for the homogenization treatment, and there is no description about the holding time, the temperature raising / cooling conditions, and the specific metal structure obtained by the homogenization treatment. There is no mention about.

  Moreover, with the thinning of the brazing sheet, the demand for corrosion resistance is also increasing. As the anticorrosion of the brazing sheet, usually, an Al—Zn alloy clad as a sacrificial material is used. However, depending on the structure of the heat exchanger, it may be necessary to give the brazing material a sacrificial anticorrosive effect. Conventionally, in such a case, a heat exchanger has been configured using a brazing sheet clad with an Al—Si brazing material added with Zn. As the Al—Si based alloy, A4045 alloy to which about 10% Si is added is usually used. However, even if Zn is added thereto, most of the added Zn flows during brazing, and there is a problem that the amount of Zn remaining after brazing decreases.

  For such a problem, techniques as described in Patent Documents 3 and 4 are known. That is, the amount of Si added is reduced to about 3 to 6%, and a part thereof flows as wax and the remainder remains solid, thereby exhibiting corrosion resistance superior to that of the prior art. However, in the brazing sheet using such a technique, molten brazing is generated at the grain boundaries of the brazing material, so that when exposed to a corrosive environment after brazing, the grain boundaries corrode locally and the remaining brazing filler crystal grains fall off. The problem remains.

  Specifically, in the technique described in Patent Document 3, there is no description about the crystal grain size of the Al—Si-based alloy clad layer after brazing and the manufacturing method for controlling it. As described above, the problem of intergranular corrosion of the Al—Si based alloy cladding layer is not recognized at all, and does not teach or suggest any solution.

  Moreover, in the technique described in patent document 4, it describes in detail about the size and number density of the Si particles in the Al—Si alloy clad layer. However, these are intended to improve erosion / corrosion resistance and brazing properties, and are not intended to prevent intergranular corrosion of the Al—Si based alloy cladding layer.

JP-A-2-282451 Japanese Patent Laid-Open No. 3-281761 JP 2008-188616 A JP 2000-309837 A

  An object of this invention is to provide the moldability and corrosion resistance which were excellent in the aluminum alloy brazing sheet. Specifically, while preventing erosion of the brazing during brazing and achieving good brazing properties, it exhibits excellent corrosion resistance, and is particularly suitable as a fluid passage constituent material for automotive heat exchangers. An aluminum alloy brazing sheet that can be used and a method for producing the same are provided.

  As a result of intensive research on the above problems, the present inventors adopt a specific process using a core material and brazing material of an aluminum alloy having a specific alloy composition, or a core material, brazing material and sacrificial anode material of an aluminum alloy. As a result, the present inventors have found that a clad material having a specific metal structure is suitable for the purpose, and have completed the present invention based on this finding.

Specifically, the onset bright in claim 1, and an aluminum alloy core and an aluminum alloy brazing sheet and a brazing material Al-Si alloy which is clad on at least one surface of the core, The core material contains Si: 0.05 to 1.2 mass%, Fe: 0.05 to 1.0 mass%, Cu: 0.05 to 1.2 mass%, Mn: 0.6 to 1.8 mass%. An aluminum alloy composed of the balance Al and unavoidable impurities, wherein the brazing material contains Si: 2.5 to 13.0 mass, Fe: 0.05 to 1.0 mass%, and the balance Al and unavoidable impurities. The distribution density of the intermetallic compound having a metal structure of 0.01 μm or more and less than 0.1 μm is 10 ^{4 to} 5 × 10 ⁵ pieces / mm ² , 0.1 μm. Production of an aluminum alloy brazing sheet in which the distribution density of intermetallic compounds of less than 1 μm is 10 ^{4 to} 5 × 10 ⁶ pieces / mm ² and the distribution density of intermetallic compounds of 1 μm or more is 5 × 10 ³ pieces / mm ² or more. A method,
Casting each of the core material and the aluminum alloy of the brazing material, homogenizing the cast core material ingot, and clad the brazing material cast on at least one surface of the homogenized core material ingot; Including a step of hot rolling the clad clad material, and a step of cold rolling the hot rolled clad material,
The homogenization step is a heating stage from heating the core material ingot to reaching the heating holding temperature, a heating holding stage for holding the core material ingot that has reached the heating holding temperature, and heating the core material ingot. A cooling step of cooling from the holding temperature, and in the heating step, the rate of temperature rise from the start of heating the core material ingot to 400 ° C. is 60 ° C./h or more, and the temperature of the core material ingot exceeds 400 ° C. The rate of temperature rise until reaching 500 ° C. is 30 ° C./h or more, and the rate of temperature rise from the temperature of the core ingot exceeding 500 ° C. until reaching the heating holding temperature is 30 ° C./h or less. In the heating and holding stage, the core material ingot is heated and held at 580 to 620 ° C. for 1 hour or more and 20 hours or less. In the cooling stage, the cooling rate from the start of cooling of the core material ingot to 500 ° C. is 30 ° C./h or less. The temperature of the core material ingot Cooling rate from below the 500 ° C. until a 400 ° C. is at 30 ° C. / h or higher,
In the middle of the cold rolling process, intermediate annealing at a temperature of 300 to 450 ° C. is performed once or more, and the final plate thickness is reached by setting the rolling rate in the final cold rolling stage to 10 to 30%. The method for producing an aluminum alloy brazing sheet is as follows.

  In Claim 2, in Claim 1, among the brazing materials, the brazing material clad on at least one surface of the core material further contains Zn: 0.5 to 5.5 mass% in addition to the respective component elements. It was supposed to be.

This onset bright in claim 3, the aluminum alloy core material and an aluminum alloy brazing sheet and a brazing material Al-Si alloy which is clad on both surfaces of the core, wherein the core material, Si: 0. Contains 0.5 to 1.2 mass%, Fe: 0.05 to 1.0 mass%, Cu: 0.05 to 1.2 mass%, Mn: 0.6 to 1.8 mass%, and the balance from Al and inevitable impurities Among the brazing materials, the brazing material clad on at least one surface of the core material is Si: 2.5-7.0 mass, Zn: 0.5-5.5 mass%, Fe: 0 0.05 to 1.0 mass%, an aluminum alloy composed of the balance Al and inevitable impurities, and a metal structure of the core material having a metal structure of 0.01 μm or more and less than 0.1 μm The intermetallic compound distribution density is 10 ^{4 to} 5 × 10 ⁵ pieces / mm ² , and the intermetallic compound distribution density is 10 ^{4 to} 5 × 10 ⁶ pieces / mm ² , 1 μm or more. the distribution density is not less 5 × 10 ³ cells / mm ² or more, an aluminum alloy brazing sheet the average crystal grain size in the thickness direction of the brazing material after brazing is at least 80% of the cladding thickness of the brazing material A manufacturing method of
A step of casting the core material and the aluminum alloy of the brazing material, a step of homogenizing the cast core material ingot, a step of clad the brazing material cast on both sides of the homogenized core material ingot, and the clad clad Including a step of hot rolling the material and a step of cold rolling the hot-rolled clad material,
The homogenization step is a heating stage from heating the core material ingot to reaching the heating holding temperature, a heating holding stage for holding the core material ingot that has reached the heating holding temperature, and heating the core material ingot. A cooling step of cooling from the holding temperature, and in the heating step, the rate of temperature rise from the start of heating the core material ingot to 400 ° C. is 60 ° C./h or more, and the temperature of the core material ingot exceeds 400 ° C. The rate of temperature rise until reaching 500 ° C. is 30 ° C./h or more, and the rate of temperature rise from the temperature of the core ingot exceeding 500 ° C. until reaching the heating holding temperature is 30 ° C./h or less. In the heating and holding stage, the core material ingot is heated and held at 580 to 620 ° C. for 1 hour or more and 20 hours or less. In the cooling stage, the cooling rate from the start of cooling of the core material ingot to 500 ° C. is 30 ° C./h or less. The temperature of the core material ingot Cooling rate from below the 500 ° C. until a 400 ° C. is at 30 ° C. / h or higher,
In the middle of the cold rolling process, intermediate annealing at a temperature of 300 to 450 ° C. is performed once or more, and the final plate thickness is reached by setting the rolling rate in the final cold rolling stage to 10 to 30%. The method for producing an aluminum alloy brazing sheet is as follows.

  In Claim 4, in any one of Claims 1 to 3, the brazing material clad on at least one surface of the core material is Ti0.05 to 0.3 mass in addition to the component elements. %, Zr: 0.05 to 0.3 mass%, Cr: 0.05 to 0.3 mass%, and V: 0.05 to 0.3 mass%, and further containing at least one selected from the group consisting of did.

  In Claim 5, in any one of Claims 1-4, the said core material is Mg: 0.05-0.5mass%, Ti0.05-0.3mass%, Zr: 0 other than each said component element. Further, at least one selected from the group consisting of 0.05 to 0.3 mass%, Cr: 0.05 to 0.3 mass%, and V: 0.05 to 0.3 mass% was further contained.

This onset bright in claim 6, the aluminum alloy core, and the brazing material on one surface cladded Al-Si based alloy of the core, a sacrificial anode material which is clad on the other surface of the core a aluminum alloy brazing sheet comprising the core material, Si: 0.05~1.2mass%, Fe: 0.05~1.0mass%, Cu: 0.05~1.2mass%, Mn: 0. It is an aluminum alloy containing 6 to 1.8 mass%, the balance being Al and inevitable impurities, and the brazing material contains Si: 2.5 to 13.0 mass, Fe: 0.05 to 1.0 mass% And the sacrificial anode material is made of Zn: 1.0 to 6.0 mass%, Si: 0.05 to 1.5 mass%, Fe: 0.0. Containing ～2.0Mass%, an aluminum alloy and the balance Al and inevitable impurities, as a metal structure of the core, the distribution density of ¹⁰ 4 to 5 × intermetallic compound of less than 0.01 [mu] m 0.1 [mu] m 10 ⁵ pieces / mm ² , distribution density of intermetallic compounds of 0.1 μm or more and less than 1 μm is 10 ^{4 to} 5 × 10 ⁶ pieces / mm ² , distribution density of intermetallic compounds of 1 μm or more is 5 × 10 ³ pieces / mm ^A method for producing an aluminum alloy brazing sheet that is ² or more ,
A step of casting the core material, the brazing material and the aluminum alloy of the sacrificial anode material, a step of homogenizing the cast core material ingot, a brazing material cast on one surface of the homogenized core material ingot, and A step of cladding the sacrificial anode material cast on the other surface, a step of hot rolling the clad clad material, and a step of cold rolling the hot rolled clad material,
The homogenization step is a heating stage from heating the core material ingot to reaching the heating holding temperature, a heating holding stage for holding the core material ingot that has reached the heating holding temperature, and heating the core material ingot. A cooling step of cooling from the holding temperature, and in the heating step, the rate of temperature rise from the start of heating the core material ingot to 400 ° C. is 60 ° C./h or more, and the temperature of the core material ingot exceeds 400 ° C. The rate of temperature rise until reaching 500 ° C. is 30 ° C./h or more, and the rate of temperature rise from the temperature of the core ingot exceeding 500 ° C. until reaching the heating holding temperature is 30 ° C./h or less. In the heating and holding stage, the core material ingot is heated and held at 580 to 620 ° C. for 1 hour or more and 20 hours or less. In the cooling stage, the cooling rate from the start of cooling of the core material ingot to 500 ° C. is 30 ° C./h or less. The temperature of the core material ingot Cooling rate from below the 500 ° C. until a 400 ° C. is at 30 ° C. / h or higher,
In the middle of the cold rolling process, intermediate annealing at a temperature of 300 to 450 ° C. is performed once or more, and the final plate thickness is reached by setting the rolling rate in the final cold rolling stage to 10 to 30%. The method for producing an aluminum alloy brazing sheet is as follows.

  According to claim 7, in claim 6, the brazing material further contains Zn: 0.5 to 5.5 mass% in addition to the component elements.

  In Claim 8, in Claim 6 or 7, the brazing material is Ti 0.05 to 0.3 mass%, Zr: 0.05 to 0.3 mass%, Cr: 0.05 to 0 in addition to the component elements. Further, at least one selected from the group consisting of 3 mass% and V: 0.05 to 0.3 mass% was further contained.

  In Claim 9, in any one of Claims 6-8, the said sacrificial anode material is Mn: 0.05-1.8 mass%, Mg: 0.5-3.0 mass% in addition to each said component element. 1 selected from the group consisting of Ti, 0.05 to 0.3 mass%, Zr: 0.05 to 0.3 mass%, Cr: 0.05 to 0.3 mass%, and V: 0.05 to 0.3 mass%. More than seeds were included.

  In Claim 10, in any one of Claims 6-9, the said core material is Mg: 0.05-0.5mass%, Ti0.05-0.3mass%, Zr: 0 other than each said component element. Further, at least one selected from the group consisting of 0.05 to 0.3 mass%, Cr: 0.05 to 0.3 mass%, and V: 0.05 to 0.3 mass% was further contained.

  According to the present invention, it is possible to produce an aluminum alloy brazing sheet that has excellent formability and does not cause brazing of the brazing during brazing. Such an aluminum alloy brazing sheet has a low strength and a high elongation at break in the state of the raw material, and since it is easy to proceed with recrystallization, no erosion of the wax due to the residual sub-crystal grains during brazing does not occur. Moreover, this aluminum alloy brazing sheet is excellent in brazing properties such as fin joint ratio and erosion resistance. Furthermore, when corrosion resistance is required, the use of a brazing material or / and a sacrificial anode material with an appropriate component provides excellent corrosion resistance, making it a heat exchanger member for automobiles, particularly lightweight and thermally conductive. It is suitably used as an excellent tube material.

  Embodiments of the aluminum alloy brazing sheet and the manufacturing method thereof according to the present invention will be described in detail below. The heating conditions at the time of brazing are usually performed by heating to about 600 ° C. and then air-cooling, and the heating method, heating rate, cooling rate, holding time, etc. are not particularly limited.

  First, an aluminum alloy brazing sheet (hereinafter simply referred to as “aluminum alloy brazing sheet”) according to the first invention will be described. This aluminum alloy brazing sheet is composed of an aluminum alloy core and an Al—Si alloy brazing material clad on at least one surface thereof.

A. Alloy Component The reason for adding the component elements of the core material and the brazing material constituting the aluminum alloy brazing sheet according to the first invention and the content thereof will be described.

1. Core Material The aluminum alloy of the core material contains Si, Fe, Cu, and Mn as essential elements, and contains Mg, Ti, Zr, Cr, and V as selective additive elements.
Si forms an Al—Mn—Si-based intermetallic compound together with Mn and improves the strength by dispersion strengthening, or improves the strength by solid solution strengthening by solid solution in the aluminum matrix. The Si content is in the range of 0.05 to 1.2 mass% (hereinafter simply referred to as “%”). If it is less than 0.05%, high-purity aluminum ingots must be used, resulting in high costs. If it exceeds 1.2%, the melting point of the core material is lowered and melted. A preferable content of Si is 0.05 to 1.0%.

  Fe easily forms an intermetallic compound having a size capable of forming a recrystallization nucleus. In order to suppress the brazing diffusion by making the crystal grain size after brazing coarse, the Fe content is 0.05 to 1.0%. If the content is less than 0.05%, high-purity aluminum ingots must be used, resulting in high costs. If the content exceeds 1.0%, the crystal grain size after brazing becomes fine and the wax diffuses. Eroded. A preferable content of Fe is 0.1 to 0.5%.

  Cu improves the strength by solid solution strengthening. The Cu content is in the range of 0.05 to 1.2%. If the content is less than 0.05%, the effect is small, and if it exceeds 1.2%, the aluminum alloy is more likely to crack during casting. The preferable content of Cu is 0.3 to 1.0%.

  Mn forms an Al—Mn—Si-based intermetallic compound together with Si and improves strength by dispersion strengthening, or solid dissolves in the aluminum matrix and improves strength by solid solution strengthening. The Mn content is 0.6 to 1.8%. If the content is less than 0.6%, the effect is small, and if it exceeds 1.8%, a giant intermetallic compound is easily formed during casting, and the plastic workability is lowered. The preferable content of Mn is 0.8 to 1.6%.

Since Mg improves strength by precipitation of Mg ₂ Si, Mg is preferably contained. The content of Mg is preferably 0.05 to 0.5%. If the content is less than 0.05%, the effect may be small, and if it exceeds 0.5%, brazing may be difficult. A more preferable content of Mg is 0.15 to 0.4%.

  Since Ti improves strength by solid solution strengthening, Ti is preferably contained. The content of Ti is preferably 0.05 to 0.3%. If the content is less than 0.05%, the effect may not be obtained. If the content exceeds 0.3%, a giant intermetallic compound is likely to be formed, and the plastic workability may be lowered. A more preferable content of Ti is 0.1 to 0.2%.

  Zr is preferably contained because it improves the strength by solid solution strengthening, and Al—Zr-based intermetallic compounds precipitate and act on the coarsening of crystal grains after brazing. The Zr content is preferably 0.05 to 0.3%. If the content is less than 0.05%, the effect may not be obtained. If the content exceeds 0.3%, a giant intermetallic compound is likely to be formed, and the plastic workability may be reduced. A more preferable content of Zr is 0.1 to 0.2%.

  Cr is preferably contained because it improves the strength by solid solution strengthening and also acts on the coarsening of the crystal grains after brazing by precipitation of an Al-Cr intermetallic compound. The content of Cr is preferably 0.05 to 0.3%. If the content is less than 0.05%, the effect may not be obtained. If the content exceeds 0.3%, a giant intermetallic compound is likely to be formed, and the plastic workability may be reduced. The more preferable content of Cr is 0.1 to 0.2%.

  V is preferably contained because it improves the strength by solid solution strengthening. The content of V is preferably 0.05 to 0.3%. If the content is less than 0.05%, the effect may not be obtained. If the content exceeds 0.3%, a giant intermetallic compound is likely to be formed, and the plastic workability may be reduced. A more preferable content of V is 0.1 to 0.2%.

  These selective additive elements of Mg, Ti, Zr, Cr, and V may be added in the core material if necessary. Further, in addition to these selectively added elements, inevitable impurities may be contained in amounts of 0.05% or less, respectively, and the total content may be 0.15% or less.

2. Brazing material The aluminum alloy of the brazing material contains Si and Fe as essential elements, and contains Zn, Ti, Zr, Cr and V as selective additive elements.
Si lowers the melting point of the material to form a liquid phase and allows brazing. The Si content is 2.5 to 13%. Below 2.5%, the resulting liquid phase is small and brazing becomes difficult to function. On the other hand, if it exceeds 13%, for example, the amount of Si diffusing into the mating material such as fins becomes excessive, and erosion occurs in which the mating material melts. The preferable content of Si is 3.5 to 12%, and the more preferable content is 7.0 to 12%.

  Fe easily forms Al-Fe-based and Al-Fe-Si-based compounds. The formation of the Al—Fe—Si-based compound reduces the effective Si amount of the brazing material. In addition, the formation of an Al-Fe-based or Al-Fe-Si-based compound reduces the brazing fluidity during brazing and inhibits brazing. For this reason, content of Fe shall be 0.05-1.0%. If the Fe content exceeds 1.0%, the brazing property is impaired as described above, and the brazing property becomes insufficient. On the other hand, if the Fe content is less than 0.05%, high-purity aluminum ingots must be used, resulting in high costs. The preferable content of Fe is 0.1 to 0.8%.

  Zn is preferably contained because the potential can be reduced and the corrosion resistance can be improved by the sacrificial anode effect by forming a potential difference with the core material. The content of Zn is preferably 0.5 to 5.5%. If the Zn content is less than 0.5%, the effect may not be sufficient. If the Zn content exceeds 5.5%, the corrosion rate increases, the sacrificial anode material disappears early, and the corrosion resistance decreases. The more preferable content of Zn is 0.5 to 3.0%.

  Since Ti improves strength by solid solution strengthening, Ti is preferably contained. The content of Ti is preferably 0.05 to 0.3%. If the content is less than 0.05%, the effect may not be obtained. If the content exceeds 0.3%, a giant intermetallic compound is likely to be formed, and the plastic workability may be lowered. A more preferable content of Ti is 0.1 to 0.2%.

  Zr is preferably contained because it improves the strength by solid solution strengthening, and Al—Zr-based intermetallic compounds precipitate and act on the coarsening of crystal grains after brazing. The Zr content is preferably 0.05 to 0.3%. If the content is less than 0.05%, the effect may not be obtained. If the content exceeds 0.3%, a giant intermetallic compound is likely to be formed, and the plastic workability may be reduced. A more preferable content of Zr is 0.1 to 0.2%.

  Cr is preferably contained because it improves the strength by solid solution strengthening and also acts on the coarsening of the crystal grains after brazing by precipitation of an Al-Cr intermetallic compound. The content of Cr is preferably 0.05 to 0.3%. If the content is less than 0.05%, the effect may not be obtained. If the content exceeds 0.3%, a giant intermetallic compound is likely to be formed, and the plastic workability may be reduced. The more preferable content of Cr is 0.1 to 0.2%.

  V is preferably contained because it improves the strength by solid solution strengthening. The content of V is preferably 0.05 to 0.3%. If the content is less than 0.05%, the effect may not be obtained. If the content exceeds 0.3%, a giant intermetallic compound is likely to be formed, and the plastic workability may be reduced. A more preferable content of V is 0.1 to 0.2%.

  These selective additive elements of Zn, Ti, Zr, Cr, and V may be added in the core material if necessary. Further, in addition to these selectively added elements, inevitable impurities may be contained in amounts of 0.05% or less, respectively, and the total content may be 0.15% or less.

B. Next, the aluminum alloy brazing sheet according to the present invention relates to the metal structure of the core material, and the distribution density of intermetallic compounds of 0.01 μm or more and less than 0.1 μm is 10 ^{4 to} 5 × 10 ⁵ pieces / before brazing. The distribution density of intermetallic compounds of mm ² , 0.1 μm or more and less than 1 μm is limited to 10 ^{4 to} 5 × 10 ⁶ pieces / mm ² , and the distribution density of intermetallic compounds of 1 μm or more is limited to 5 × 10 ³ pieces / mm ² or more. Is done. The reason for limitation will be described below. In addition, the size of the intermetallic compound here refers to an equivalent circle diameter.

  In order to impart excellent formability to the brazing sheet, the rolling rate from the intermediate annealing to the final sheet thickness by cold rolling is lowered in the manufacturing process. Thereby, the intensity | strength in the state of a raw material becomes low, and the outstanding moldability is obtained. However, if the rolling rate is too low, subgrains remain during brazing, and brazing of the core material occurs. When wax erosion of the core material occurs, the fluidity of the wax decreases and brazeability is hindered. Furthermore, when exposed to a corrosive environment, the eroded portion of the wax causes intergranular corrosion, which also reduces the corrosion resistance. On the other hand, if the rolling rate is too high, the strength of the material increases, and excellent formability cannot be obtained. Therefore, it is necessary to obtain a core material structure in which sub-crystal grains hardly remain at the time of brazing at the same rolling rate and the strength of the material is low.

  In this regard, the present inventors have conducted extensive research. As a result, intermetallic compounds of 1 μm or more in the core material promote recrystallization of the core material during brazing, while intermetallic compounds of less than 1 μm suppress recrystallization of the core material during brazing. In addition, the present inventors have found that the strength in the state of the material is increased.

The inventors of the present invention conducted further detailed examination on this point. As a result, the distribution density of the intermetallic compound of less than 1 μm should be low, and the distribution density of the intermetallic compound of from 0.01 μm to less than 0.1 μm is When the distribution density of the intermetallic compound of 10 ⁵ pieces / mm ² or less and 0.1 μm or more and less than 1 μm is 5 × 10 ⁶ pieces / mm ² or less, the erosion of the wax on the core material is suppressed, and in the state of the material It has been found that the strength of is low, and excellent moldability and corrosion resistance can be obtained. When the distribution density of intermetallic compounds of 0.01 μm or more and less than 0.1 μm exceeds 5 × 10 ⁵ pieces / mm ² , or the distribution density of intermetallic compounds of 0.1 μm or more and less than 1 μm is 5 × 10 ⁶ pieces / mm ^2. If it exceeds mm ² , wax erosion to the core material is likely to occur, and the strength of the material increases, so that excellent moldability and corrosion resistance cannot be obtained.

From the viewpoint of formability, there is no lower limit for the distribution density of intermetallic compounds of less than 1 μm. However, with the components of the aluminum alloy brazing sheet of the present invention, it is difficult to completely eliminate intermetallic compounds of less than 1 μm. Actually, the intermetallic compound of 0.01 μm or more and less than 0.1 μm and the intermetallic compound of 0.1 μm or more and less than 1 μm have a distribution density of at least 10 ⁴ / mm ² .

On the other hand, an intermetallic compound having a size of 1 μm or more promotes recrystallization of the core material during brazing and suppresses braze erosion of the core material. It has been found that when the distribution density is 10 ³ pieces / mm ² or more, the erosion of the wax into the core material is suppressed. When the distribution density is less than 10 ³ pieces / mm ² , wax erosion to the core material is likely to occur. A more preferable distribution density of the intermetallic compound of 1 μm or more is 5 × 10 ³ pieces / mm ² or more.

C. Next, when the brazing material contains Zn, the average crystal grain size in the thickness direction of the brazing material remaining in the state after brazing is the brazing material. It has also been found that it has particularly excellent corrosion resistance when it is 80% or more of the cladding thickness of the material. The reason will be described below.

  As already mentioned, the aluminum alloy brazing sheet of the present invention generates molten brazing at the grain boundaries of the brazing material by brazing, and therefore the grain boundaries corrode locally when exposed to a corrosive environment after brazing. The average crystal grain size in the plate thickness direction of the brazing material after brazing (hereinafter, “average crystal grain size in the plate thickness direction” is simply referred to as “crystal grain size”) is 80% of the clad thickness of the brazing material. In the following cases, many grain boundaries exist at the interface between the brazing material and the brazing material or at the interface between the brazing material and the core material in the thickness direction. For this reason, crystal grains are likely to fall off due to intergranular corrosion. As a result, the brazing material disappears early, and sufficient corrosion resistance cannot be obtained. When the crystal grain size of the brazing material after brazing is 80% or more of the cladding thickness of the brazing material, dropout of crystal grains due to intergranular corrosion is suppressed, and sufficient corrosion resistance can be obtained. The preferable crystal grain size of the brazing material after brazing is 90% or more of the cladding thickness of the brazing material.

  Next, the aluminum alloy brazing sheet according to the second invention will be described. This aluminum alloy brazing sheet is composed of an aluminum alloy core material and an Al—Si alloy brazing material clad on both sides thereof. The difference from the first invention is that the upper limit of the Si content of the Al—Si-based alloy clad on at least one surface of the core material is as small as 7.0%, containing Zn as an essential element, The average crystal grain size in the plate thickness direction is defined as a constituent requirement of the invention. Below, it demonstrates centering on the part which is different from 1st invention.

A. Alloy components Core Material The aluminum alloy of the core material is the same as that in the first invention in the reason for addition and content.

2. Brazing material The aluminum alloy of the brazing material contains Si, Fe and Zn as essential elements, and contains Zn, Ti, Zr, Cr and V as selective additive elements. Fe, Zn, Ti, Zr, Cr, and V are the same as in the first invention in the reason and content of addition, and inevitable impurities.

  In the second invention, Zn is contained as an essential element in order to positively give the brazing material a sacrificial anode effect. The Zn content is 0.5 to 5.5%. If the Zn content is less than 0.5%, the effect is not sufficient. If the Zn content exceeds 5.5%, the corrosion rate increases, the sacrificial anode material disappears early and the corrosion resistance decreases. The preferable content of Zn is 0.5 to 3.0%.

  The reason for adding Si is the same as in the first invention, but its content is 2.5 to 7.0%. When the brazing material has a sacrificial anode effect, it is preferable that a liquid phase is generated during brazing and a part of the brazing material remains as a solid phase. In this case, the Si content is 2.5 to 7.0%, preferably 2.5 to 6.0%.

B. Metal structure The metal structure is the same as that of the first invention described above.

C. In this second invention, since the brazing material contains Zn as an essential element, the average crystal grain size in the thickness direction of the brazing material remaining in the state after brazing. However, it is defined as a constituent requirement of the invention that it is 80% or more of the cladding thickness of this brazing material. The reason why the average crystal grain size in the thickness direction of the brazing material is 80% or more of the clad thickness of the brazing material is the same as in the first invention.

  Next, an aluminum alloy brazing sheet according to the third invention will be described. This aluminum alloy brazing sheet is composed of an aluminum alloy core, an Al—Si alloy brazing material clad on one surface, and a sacrificial anode material clad on the other surface. The difference from the first invention is that the brazing sheet is provided with a sacrificial anode material. Below, it demonstrates centering on the part which is different from 1st invention.

A. Alloy components Core Material The aluminum alloy of the core material is the same as that in the first invention in the reason for addition and content.

2. Brazing material The aluminum alloy of the brazing material is the same as in the first invention in the reason for addition and content.

3. Sacrificial anode material When the brazing sheet is required to have high corrosion resistance in the environment where the heat exchanger is used, one in which a sacrificial anode material is clad on one side of the core material is used. The aluminum alloy of the sacrificial anode material contains Zn, Si and Fe as essential elements, and contains Mn, Mg, Ti, Zr, Cr and V as selective additive elements.

  Zn can lower the 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 1.0 to 6.0%. If the Zn content is less than 1.0%, the effect is not sufficient. If the Zn content exceeds 6.0%, the corrosion rate increases, the sacrificial anode material disappears early, and the corrosion resistance decreases. The preferable content of Zn is 2.0 to 5.0%.

Si forms an Al—Fe—Mn—Si compound together with Fe and Mn, and improves the strength by dispersion strengthening, or improves the strength by solid solution and solid solution strengthening in the aluminum matrix. Moreover, it reacts with Mg diffusing from the core material during brazing to form an Mg ₂ Si compound, thereby improving the strength. 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 sacrificial anode material is lowered and melted, and since the potential of the sacrificial anode material is made noble, the sacrificial anode effect is inhibited and the corrosion resistance is lowered. The preferable content of Si is 1.2% or less.

  Fe forms an Al—Fe—Mn—Si compound together with Si and Mn, and improves strength by dispersion strengthening. The Fe content 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 huge intermetallic compound is likely to be formed at the time of casting, cracking may occur, and the plastic workability is lowered. The preferable content of Fe is 1.5% or less.

  Mn is preferably contained because it improves strength and corrosion resistance. The Mn content is preferably 1.8% or less. If the content exceeds 1.8%, a giant intermetallic compound is likely to be formed during casting, which may reduce plastic workability. Moreover, in order to make the potential of the sacrificial anode material noble, the sacrificial anode effect may be hindered to reduce the corrosion resistance. A more preferable content of Mn is 1.5% or less.

Since Mg improves strength by precipitation of Mg ₂ Si, Mg is preferably contained. Not only the strength of the sacrificial anode material itself is improved, but also Mg diffuses into the core material by brazing heat and the strength of the core material is also improved. The content of Mg is preferably 0.5 to 3.0%. If the content is less than 0.5%, the effect may be small, and if it exceeds 3.0%, it is difficult to perform pressure bonding during hot clad rolling. A more preferable content of Mg is 0.5 to 2.0%.

  Ti is preferably contained because it improves strength by solid solution strengthening and also improves corrosion resistance. The content of Ti is preferably 0.02 to 0.3%. When the content is less than 0.02%, the effect may not be obtained. When the content exceeds 0.3%, it becomes easy to form a giant intermetallic compound, and cracking occurs or plastic workability is lowered. There is. A more preferable content of Ti is 0.1 to 0.2%.

  Zr is preferably contained because it improves the strength by solid solution strengthening, and Al—Zr-based intermetallic compounds precipitate and act on the coarsening of crystal grains after brazing. The Zr content is preferably 0.05 to 0.3%. When the content is less than 0.05%, the effect may not be obtained. When the content exceeds 0.3%, it becomes easy to form a giant intermetallic compound, and cracking occurs or plastic workability is lowered. There is. A more preferable content of Zr is 0.1 to 0.2%.

  Cr is preferably contained because it improves the strength by solid solution strengthening and also acts on the coarsening of the crystal grains after brazing by precipitation of an Al-Cr intermetallic compound. The content of Cr is preferably 0.05 to 0.3%. When the content is less than 0.05%, the effect may not be obtained. When the content exceeds 0.3%, it becomes easy to form a giant intermetallic compound, and cracking occurs or plastic workability is lowered. There is. The more preferable content of Cr is 0.1 to 0.2%.

  V is preferably contained because it improves strength by solid solution strengthening and also improves corrosion resistance. The content of V is preferably 0.02 to 0.3%. When the content is less than 0.02%, the effect may not be obtained. When the content exceeds 0.3%, it becomes easy to form a giant intermetallic compound, and cracking occurs or plastic workability is lowered. There is. A more preferable content of V is 0.1 to 0.2%.

  These selective additive elements of Mn, Mg, Ti, Zr, Cr, and V may be added in the core material if necessary. Further, in addition to these selectively added elements, inevitable impurities may be contained in amounts of 0.05% or less, respectively, and the total content may be 0.15% or less.

B. Metal structure, and C.I. The average crystal grain size in the plate thickness direction of the brazing material The metal structure and the average crystal grain size in the plate thickness direction of the brazing material are the same as in the first invention described above.

  Next, as a method for producing an aluminum alloy brazing sheet of the present invention, first, a method for producing an aluminum alloy brazing sheet according to the first and second inventions will be described.

  The manufacturing process of the aluminum alloy brazing sheet of the first and second inventions includes a step of casting the core material and the aluminum alloy of the brazing material, a step of homogenizing the cast core material ingot, and a homogenized core material ingot. A step of cladding a brazing material cast on at least one surface, a step of hot rolling the clad clad material, and a step of cold rolling the hot rolled clad material. This includes a cold rolling process in which intermediate annealing at a temperature of 1 is applied at least once. When the intermediate annealing is performed once in the course of the cold rolling process, the second cold rolling stage, which is the final cold rolling stage, is performed sequentially through the first cold rolling stage and the intermediate annealing. The Further, when the intermediate annealing is performed twice, the first cold rolling step, the first intermediate annealing, the second cold rolling step, and the second intermediate annealing are sequentially performed to obtain the final cold. A third cold rolling stage, which is a rolling stage, is performed. Similarly, when the intermediate annealing is performed three times or more, the cold rolling step is performed with each intermediate annealing interposed therebetween.

  Here, in the step of cold rolling to the final plate thickness, that is, in the final cold rolling stage, the rolling rate is limited to 10 to 30%. The reason for the limitation will be described from the viewpoints of moldability and corrosion resistance.

  In order for the brazing sheet of the present invention to have excellent formability, it is necessary to reduce the rolling rate until the final plate thickness is reached in the final cold rolling step. When the rolling rate is 30% or less, the brazing sheet has low form strength and exhibits excellent formability. When the rolling rate is greater than 30%, the brazing sheet has high strength in the raw material state and does not exhibit excellent formability. In addition, when the rolling rate is less than 10%, even if the metal structure of the core material satisfies the above-mentioned conditions, the sub-crystal grains remain during brazing and the core material is eroded by brazing.

  On the other hand, from the viewpoint of corrosion resistance, as described above, excellent corrosion resistance is exhibited when the crystal grain size of the brazing material after brazing is larger than the cladding thickness of the brazing material. The inventors have made detailed studies on the relationship between the crystal grain size and the rolling rate. As a result, it has been found that the crystal grain size after brazing of the brazing material becomes larger than the clad thickness of the brazing material only when the rolling rate is 30% or less. When the rolling rate exceeds 30%, crystal grains fall off due to intergranular corrosion of the brazing material, and excellent corrosion resistance cannot be obtained. On the other hand, when the rolling rate is less than 10%, the strain for inducing recrystallization of the core material is not sufficient, and the core material does not recrystallize at the time of brazing, so that brazing of the core material occurs. As a result, intergranular corrosion occurs in the core material, so that excellent corrosion resistance cannot be obtained. A more preferable rolling ratio is 10 to 25%. The intermediate annealing temperature is preferably 300 to 550 ° C. If it is less than 300 ° C., the core material may not be completely recrystallized, and if it exceeds 550 ° C., the brazing material may be melted. A batch type furnace may be used for the intermediate annealing, or a continuous type furnace may be used. When using a batch type furnace, the holding time of the intermediate annealing is preferably 1 to 10 hours. If it is less than 1 hour, the core material may not be completely recrystallized. If it exceeds 10 hours, the cost becomes high.

  Next, in the homogenization step of heating the core material ingot, the heating condition and the cooling condition are limited in detail. The reason for the limitation will be described.

  As already described, in the brazing sheet of the present invention, a small amount of fine intermetallic compounds of less than 1 μm are present in the core metal structure and a large amount of coarse compounds of 1 μm or more are present. In order to obtain such a metal structure, it is preferable that the heating and holding temperature in the homogenization step is high. When the heating and holding temperature is 580 ° C. or higher, the metal structure of the core material satisfies the above-described conditions, but when it is lower than 580 ° C., the conditions are not satisfied. On the other hand, if the heating and holding temperature in the homogenization step exceeds 620 ° C., the core material ingot may be locally melted. The heating and holding time is 1 hour or more and 20 hours or less. If it is less than 1 hour, the effect of coarsening the intermetallic compound is insufficient, while if it exceeds 20 hours, the cost increases.

  Further, in the temperature raising and cooling process, a fine intermetallic compound is generated in a temperature range of less than 500 ° C. Therefore, it is necessary to increase the rate of temperature rise and cooling in this temperature range as much as possible. At the time of temperature increase, the rate of temperature increase from the start of heating of the core material ingot to the temperature of the core material ingot reaching 400 ° C is set to 60 ° C / h or more, and the temperature of the core material ingot exceeds 400 ° C to 500 ° C. The rate of temperature increase until the temperature reached 30 ° C./h or more. On the other hand, at the time of cooling, the cooling rate from the temperature of the core material ingot to below 400 ° C until reaching 400 ° C was set to 30 ° C / h or more. By setting the heating rate and the cooling rate as described above, a small amount of fine intermetallic compounds of less than 1 μm can be present.

On the other hand, in the temperature range of 500 ° C. or higher, fine intermetallic compounds re-dissolve in the matrix, and coarse intermetallic compounds grow larger. Therefore, the temperature raising and cooling rates in this temperature range must be as slow as possible. There is. At the time of temperature increase, the rate of temperature increase from the temperature of the core material ingot exceeding 500 ° C. to the heating holding temperature is set to 30 ° C./h or less until the temperature of the core material ingot reaches 500 ° C. from the start of cooling. The cooling rate was set to 30 ° C./h or less. By setting such a temperature rising rate and cooling rate, a small amount of fine intermetallic compounds of less than 1 μm can be present and a large amount of coarse intermetallic compounds of 1 μm or more can be present.
When the aluminum alloy brazing sheet of the present invention is produced under the above limiting conditions, the metal structure satisfies the above-described conditions, and excellent formability and corrosion resistance are achieved.

  In addition, in the manufacturing process of the aluminum alloy brazing sheet of the present invention, it may be subjected to a finish annealing process for the purpose of further improving formability after being subjected to the cold rolling process to the final plate thickness. The finish annealing step is preferably performed at 150 to 550 ° C. If it is less than 150 degreeC, the effect of a moldability improvement will be few, and when it exceeds 550 degreeC, there exists a possibility that a brazing material may fuse | melt. Moreover, there is no restriction | limiting in particular in the thickness of the aluminum alloy brazing sheet of this invention, and the clad rate of a brazing material layer or a sacrificial anode material layer. Usually, when used as a tube material of a heat exchanger for automobiles, a thin brazing sheet of 0.6 mm or less is often used. However, it is not limited to the plate thickness within this range, and it is of course possible to use it as a relatively thick material of about several mm. The single-sided cladding rate of the brazing material layer is usually about 3 to 25%.

  Next, the manufacturing method of the aluminum alloy brazing sheet which concerns on 3rd invention is demonstrated.

  The manufacturing process of the aluminum alloy brazing sheet of the third invention includes the steps of casting the core material, the brazing material and the sacrificial anode material, respectively, homogenizing the cast core material ingot, and homogenized core material casting. Clad the brazing material cast on one side of the lump, the sacrificial anode material cast on the other side, the hot rolling of the clad clad material, and the hot rolled clad material cold It is a process of rolling, and includes a cold rolling process in which intermediate annealing at a temperature of 300 to 450 ° C. is performed once or more in the middle. The cold rolling stage and the intermediate annealing in the cold rolling process are the same as those in the first and second inventions.

  The manufacturing process of the aluminum alloy brazing sheet of the third invention differs from the manufacturing processes of the first and second aluminum alloy brazing sheets, including the step of casting the aluminum alloy of the sacrificial anode material, which is cast in the cladding step. The sacrificial anode material is clad on the other surface of the homogenized core material ingot.

  Regarding the limitation of the rolling rate in the final cold rolling stage in the cold rolling process and the limitation of the heating condition and the cooling condition in the homogenization process for heating the core ingot, the aluminum according to the first and second inventions This is the same as in the method for producing an alloy brazing sheet.

  EXAMPLES Next, although this invention is demonstrated further in detail based on an Example, this invention is not restrict | limited to these.

Invention Examples 1 to 13 and 35 to 44, and Comparative Examples 14 to 34 and 45 to 61
The core material alloy having the alloy composition shown in Table 1, the brazing material alloy having the alloy composition shown in Table 2, and the sacrificial anode material having the alloy composition shown in Table 3 were cast by DC casting, and the core material alloy is shown in Table 4. Homogenization treatment was performed under conditions, and each side was chamfered and finished. In Table 4, the temperature increase rate until the temperature of the ingot reaches 400 ° C. is shown in the “A” column, and the temperature increase rate until the temperature of the ingot exceeds 400 ° C. and reaches 500 ° C. “B” column, the temperature rising rate from the temperature of the ingot exceeding 500 ° C. until reaching the heating holding temperature is indicated in the “C” column, and the temperature of the ingot reaches 500 ° C. after starting the cooling. The cooling rate until is shown in the “D” column, and the cooling rate until the temperature of the ingot is lowered from 500 ° C. to 400 ° C. is shown in the “E” column. In addition, Table 4 shows the ultimate temperature and holding time during holding.

  Using these alloys, in the first and second embodiments, the brazing material of Table 2 is combined as the skin material 1 on one side of the core material, and the brazing material of Table 2 as the skin material 2 on the other surface. Combined materials. Note that there are also two-layer materials that are not combined with the skin material 2. In the third embodiment of the invention, the brazing material of Table 2 was combined as the skin material 1 on one side of the core material, and the sacrificial anode material of Table 3 was combined as the skin material 2 on the other surface. The clad rate was 10% on each side. These laminated materials were subjected to a hot rolling process at 530 ° C. for 3 hours to prepare a clad material having a thickness of 3.5 mm. The material temperature at the start of hot rolling was 510 ° C. The clad material thus produced was subjected to a cold rolling process. In the cold rolling process, first, the first cold rolling stage is performed, then intermediate annealing (condition: held at 400 ° C. for 5 hours) is performed, and further, the final cold rolling stage, which is the second cold rolling stage. Finally, a brazing sheet sample having a thickness of 0.4 mm and having an H1n temper was prepared. Tables 5 and 6 show the core material of each brazing sheet sample, the combination of the skin material 1 and the skin material 2, the manufacturing process and productivity shown in Table 4, and the rolling rate in the final cold rolling stage after the intermediate annealing. In addition, no problems occurred in the manufacturing process, and those that could be rolled to a final plate thickness of 0.4 mm passed the manufacturability (O), and excessive elongation of the sacrificial anode material during manufacture, core material and sacrificial anode The product with poor press bonding with the material was rejected (x) in manufacturability.

  Tables 7 and 8 show the results of subjecting these brazing sheet samples to the following evaluations.

(Measurement of density of intermetallic compounds)
The core material portion of each brazing sheet sample was examined by thinning the L-LT surface by polishing and observation with a scanning transmission electron microscope (STEM). At this time, the film thickness of the observation portion was measured using an electron spectrometer (EELS), and STEM observation was performed only at a location where the film thickness was 0.1 to 0.15 μm. The density of the intermetallic compound of each size was calculated | required by observing one by one and image-analyzing the STEM photograph of each visual field. In addition, the distribution density of the intermetallic compounds shown in Tables 7 and 8 was expressed as an average value obtained from 10 fields of view.

(Measurement of crystal grain size of brazing material)
The L-ST surface of each brazing sheet sample is polished and etched with Keller solution, and the contrast thickness due to the difference in alloy components is observed with a microscope to measure the cladding thickness A of the skin material 1 did. On the other hand, the L-ST surface of the same brazing sheet sample subjected to brazing addition heat at 600 ° C. for 3 minutes was surfaced by polishing, anodized using Barker's solution, and observed with a polarized microscope. The average crystal grain size B in the thickness direction of the material was measured. The observation magnification was 100 times, and the average of all the crystal grains of the brazing material in the three fields of view was taken as the average crystal grain diameter. A value of (B / A) × 100 was calculated from the obtained A and B, and when it was 80% or more, it was regarded as acceptable (◯), and when it was less than that, it was regarded as unacceptable (×). Note that the evaluation was performed only on the sample in which Zn was added to the skin material 1.

(Measurement of tensile strength and elongation at break of brazing sheet)
Each brazing sheet sample 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 and elongation at break were read from the obtained stress-strain curve. As a result, the case where the tensile strength was 200 MPa or less and the elongation at break was 5.0% or more was regarded as acceptable, and the case other than this was regarded as unacceptable.

(Measurement of tensile strength after brazing)
In place of the brazing sheet sample, the tensile strength was read from the stress-strain curve of the sample after brazing heat applied at 600 ° C. for 3 minutes in the same manner as the brazing sheet sample before brazing. The case where the tensile strength was 130 MPa or more was regarded as acceptable, and the other cases were regarded as unacceptable.

Evaluation of brazeability Alloy 3003 is processed into fins by corrugation molding, combined with 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. did. The test core has a fin joint ratio of 95% or more, and when the sample after brazing has not melted and brazed to the core material, the brazeability is passed (◯), and the fin joint ratio is 95. Less than% or when brazing occurred in the sample after brazing, the brazing property was judged as rejected (x). The presence or absence of wax erosion on the core material was judged by polishing the cross section of the sample heated by brazing, etching with Keller solution, and observing with a microscope.

Measurement of Corrosion Depth A brazing sheet sample was heat treated at 600 ° C. for 3 minutes (corresponding to brazing addition heat), then cut into 50 mm × 50 mm, and the opposite side of the test surface was masked with resin. Here, the corrosion resistance of the brazing material was tested using the brazing material surface to which Zn was added as a test surface. In addition, when the brazing material to which Zn was added was not provided on any surface, the corrosion resistance of the brazing material was not evaluated. The corrosion resistance of the sacrificial anode material was tested using the sacrificial anode material surface as a test surface. When the test surface is a brazing material, it was subjected to the SWAAT test based on ASTM-G85, and the one that did not cause corrosion penetration in 1000 hours passed (◎), and the one that caused corrosion penetration in 500 hours or more and less than 1000 hours A pass (◯), a case where corrosion penetration occurred in less than 500 hours was determined to be a failure (x). ^If the test surface is a sacrificial anode ^{_{material, Cl - 500ppm, SO 4 2-}} 100ppm, 8 hours at a high temperature water of 88 ° C. containing Cu 2+ 10 ppm, 3 months cycle immersion test in which one cycle standing at room temperature 16 hours The test was conducted for a period of time, and no corrosion penetration occurred.

  In Inventive Examples 1 to 13 and 35 to 44, the conditions specified in the present invention are satisfied, the manufacturability, the tensile strength and elongation at break of the brazing sheet, the tensile strength after brazing, the brazing property, and All of the corrosion depths (corrosion resistance) of the sacrificial anode material were acceptable. In addition, the inventive examples 1 to 13, 37 to 44 and the comparative examples 14 to 21 and 23 to 30 in which an appropriate amount of Zn is added to the brazing material is excellent in the corrosion resistance of the brazing material surface. In Invention Examples 1 to 13 and 37 to 43 in which the metal structures defined in the invention were obtained, the corrosion resistance of the brazing material surface was particularly excellent. In Example 44 and Comparative Examples 20, 21, 29, and 30, the metal structure defined in the present invention is obtained. However, in Example 44, the amount of Si in the brazing material exceeds 7%. In Comparative Examples 20 and 29, the rolling rate was too high and the brazing material crystal grain system was smaller than 80% of the brazing material clad thickness. Therefore, in Comparative Examples 21 and 30, the rolling rate was too low and the brazing of the core material was eroded. Therefore, the corrosion resistance of the brazing material surface was not particularly excellent.

In Comparative Examples 14 and 23, the heating rate in the homogenization treatment of the core material ingot was too slow from the start of heating until reaching 400 ° C., so that brazing erosion of the core material occurred and the brazing property was not good. It was a pass.
In Comparative Examples 15 and 24, the heating rate of the homogenization treatment of the core material ingot from 400 ° C. to 500 ° C. was too slow. It was a pass.
In Comparative Examples 16 and 25, the heating rate after reaching 500 ° C. in the heating for homogenization treatment of the core material ingot was too high, so that the core material was eroded and the brazing property was unacceptable.
In Comparative Examples 17 and 26, since the heating and holding temperature in the homogenization treatment of the core material ingot was too low, brazing erosion of the core material occurred and the brazing property was unacceptable.
In Comparative Examples 18 and 27, since the cooling rate from the start of cooling in the homogenization cooling of the core material ingot to 500 ° C. was too high, brazing erosion of the core material occurred and the brazing property was rejected. Met.
In Comparative Examples 19 and 28, in the cooling of the homogenization processing of the core material ingot, the cooling rate from reaching below 500 ° C. to reaching 400 ° C. was too slow, so that the core material was subjected to braze erosion and failed to braze. Met.
In Comparative Examples 20 and 29, since the rolling rate in the final cold rolling stage was too high, the tensile strength and elongation of the brazing sheet material were unacceptable.
In Comparative Examples 21 and 30, since the rolling rate in the final cold rolling stage was too low, the rolling rate was too low, so that brazing of the core material occurred and the brazing property was unacceptable.
In Comparative Example 22, since the heating and holding temperature in the homogenization treatment of the core material ingot was too high, the core material ingot melted locally and the core material could not be manufactured.
In Comparative Example 31, since there was too much Si component in the core material, the core material melted during brazing and the brazeability was unacceptable.
In Comparative Example 32, since there was too much Fe component in the core material, brazing erosion of the core material occurred, and the brazeability was unacceptable.
In Comparative Example 33, since there was too much Fe component in the brazing material, unbonding with the fin occurred, and the brazing property was unacceptable.
In Comparative Example 34, since there was too much Si component in the brazing material, the fins melted and the brazeability was unacceptable.

In Comparative Example 45, since there was too much Zn component in the brazing material, the corrosion resistance of the brazing material was unacceptable.
In Comparative Example 46, since the Zn component of the brazing material was too small, the corrosion resistance of the brazing material was unacceptable.
In Comparative Example 47, since there was too much Mg component in the core material, unbonding with the fin occurred, and the brazing property was unacceptable.
In Comparative Example 48, since there were too many Ti, Cr, Zr, and V components in the core material, cracks occurred during rolling, and the material could not be manufactured.
In Comparative Example 49, since the Mn component of the core material was too much, cracking occurred during rolling, and the material could not be manufactured.
In Comparative Example 50, since there was too much Cu component in the core material, cracks occurred during casting, and the material could not be manufactured.
In Comparative Example 51, since the Mn component of the core material was too small, the tensile strength after brazing was not acceptable.
In Comparative Example 52, since the Cu component of the core material was too small, the tensile strength after brazing was unacceptable.
In Comparative Example 53, since the Si component of the core material was too small, the tensile strength after brazing was not acceptable.
In Comparative Example 54, since there was too little Si component of the brazing material, unbonding with the fin occurred, and the brazing property was unacceptable.
In Comparative Example 55, since there were too many Ti, Cr, Zr, and V components in the brazing material, cracks occurred during rolling, and the material could not be manufactured.
In Comparative Example 56, the sacrificial anode material failed in corrosion resistance because the sacrificial anode material contained too much Si component.
In Comparative Example 57, since there were too many Fe components in the sacrificial anode material, cracking occurred during rolling, and the material could not be manufactured.
In Comparative Example 58, the sacrificial anode material contained too many Mn, Ti, Cr, Zr, and V components, so that cracking occurred during rolling, and the material could not be manufactured.
In Comparative Example 59, since the Zn component of the sacrificial anode material was too small, the corrosion resistance of the sacrificial anode material was unacceptable.
In Comparative Example 60, the sacrificial anode material failed in the corrosion resistance because there was too much Zn component in the sacrificial anode material.
In Comparative Example 61, since there was too much Mg component of the sacrificial anode material, the core material and the sacrificial material could not be pressure-bonded during hot rolling, and the material could not be manufactured.

  The aluminum alloy brazing sheet according to the present invention has excellent formability due to its low strength in the raw material state and high elongation at break, and no subcrystalline grains remain during brazing, so that corrosion of the core material occurs due to wax. Excellent corrosion resistance because it is not present. In addition, this brazing sheet has excellent brazing properties such as fin joint ratio and erosion resistance, is lightweight as a heat exchanger for automobiles and has excellent thermal conductivity, and is particularly suitable for use as a tube material for automotive heat exchangers. It is.

Claims (10)

And aluminum alloy core and an aluminum alloy brazing sheet and a brazing material Al-Si alloy which is clad on at least one surface of the core, wherein the core material, Si: 0.05~1.2mass% Fe: 0.05-1.0 mass%, Cu: 0.05-1.2 mass%, Mn: 0.6-1.8 mass%, an aluminum alloy comprising the balance Al and inevitable impurities, The brazing material is an aluminum alloy containing Si: 2.5-13.0 mass, Fe: 0.05-1.0 mass%, the balance being Al and inevitable impurities, and the metal structure of the core material is 0 distribution density of the distribution density of 0.1μm below the intermetallic compound or .01μm is ¹⁰ 4 ^~5 × ^{10 5} cells ^/ mm 2, an intermetallic compound of less than 1μm than 0.1μm 10 ⁴ ~5 × 10 ⁶ cells / ^mm 2, an aluminum alloy brazing sheet manufacturing method is the distribution density of the above intermetallic compound 1μm is 5 × 10 ³ cells / mm ² or more,
Casting each of the core material and the aluminum alloy of the brazing material, homogenizing the cast core material ingot, and clad the brazing material cast on at least one surface of the homogenized core material ingot; Including a step of hot rolling the clad clad material, and a step of cold rolling the hot rolled clad material,
The homogenization step is a heating stage from heating the core material ingot to reaching the heating holding temperature, a heating holding stage for holding the core material ingot that has reached the heating holding temperature, and heating the core material ingot. A cooling step of cooling from the holding temperature, and in the heating step, the rate of temperature rise from the start of heating the core material ingot to 400 ° C. is 60 ° C./h or more, and the temperature of the core material ingot exceeds 400 ° C. The rate of temperature rise until reaching 500 ° C. is 30 ° C./h or more, and the rate of temperature rise from the temperature of the core ingot exceeding 500 ° C. until reaching the heating holding temperature is 30 ° C./h or less. In the heating and holding stage, the core material ingot is heated and held at 580 to 620 ° C. for 1 hour or more and 20 hours or less. In the cooling stage, the cooling rate from the start of cooling of the core material ingot to 500 ° C. is 30 ° C./h or less. The temperature of the core material ingot Cooling rate from below the 500 ° C. until a 400 ° C. is at 30 ° C. / h or higher,
In the middle of the cold rolling process, intermediate annealing at a temperature of 300 to 450 ° C. is performed once or more, and the final plate thickness is reached by setting the rolling rate in the final cold rolling stage to 10 to 30%. A method for producing an aluminum alloy brazing sheet . 2. The aluminum alloy according to claim 1, wherein the brazing material clad on at least one surface of the core material further contains Zn: 0.5 to 5.5 mass% in addition to the component elements. A method for producing a brazing sheet. And aluminum alloy core and an aluminum alloy brazing sheet and a brazing material Al-Si alloy which is clad on both surfaces of the core, wherein the core material, Si: 0.05~1.2mass%, Fe: It is an aluminum alloy containing 0.05 to 1.0 mass%, Cu: 0.05 to 1.2 mass%, Mn: 0.6 to 1.8 mass%, the balance being Al and inevitable impurities, Of these, the brazing material clad on at least one surface of the core material contains Si: 2.5-7.0 mass, Zn: 0.5-5.5 mass%, Fe: 0.05-1.0 mass% and, an aluminum alloy and the balance Al and unavoidable impurities, the distribution density of the metal structure of the core, the intermetallic compound of less than 0.01 [mu] m 0.1 [mu] m is 10 To 5 × 10 ⁵ cells ^/ mm 2, the distribution density of the intermetallic compound of less than 0.1 [mu] m 1 [mu] m is ¹⁰ 4 ^~5 × ^{10 6} cells / ^mm 2, the distribution density of the above intermetallic compound 1 [mu] m is 5 × 10 ³ pieces / mm ² or more, a said brazing material thickness manufacturing method of an aluminum alloy brazing sheet average crystal grain size of more than 80% of the cladding thickness of the brazing material in a direction after brazing,
A step of casting the core material and the aluminum alloy of the brazing material, a step of homogenizing the cast core material ingot, a step of clad the brazing material cast on both sides of the homogenized core material ingot, and the clad clad Including a step of hot rolling the material and a step of cold rolling the hot-rolled clad material,
The homogenization step is a heating stage from heating the core material ingot to reaching the heating holding temperature, a heating holding stage for holding the core material ingot that has reached the heating holding temperature, and heating the core material ingot. A cooling step of cooling from the holding temperature, and in the heating step, the rate of temperature rise from the start of heating the core material ingot to 400 ° C. is 60 ° C./h or more, and the temperature of the core material ingot exceeds 400 ° C. The rate of temperature rise until reaching 500 ° C. is 30 ° C./h or more, and the rate of temperature rise from the temperature of the core ingot exceeding 500 ° C. until reaching the heating holding temperature is 30 ° C./h or less. In the heating and holding stage, the core material ingot is heated and held at 580 to 620 ° C. for 1 hour or more and 20 hours or less. In the cooling stage, the cooling rate from the start of cooling of the core material ingot to 500 ° C. is 30 ° C./h or less. The temperature of the core material ingot Cooling rate from below the 500 ° C. until a 400 ° C. is at 30 ° C. / h or higher,
In the middle of the cold rolling process, intermediate annealing at a temperature of 300 to 450 ° C. is performed once or more, and the final plate thickness is reached by setting the rolling rate in the final cold rolling stage to 10 to 30%. A method for producing an aluminum alloy brazing sheet . Among the brazing materials, brazing material clad on at least one surface of the core material is Ti 0.05 to 0.3 mass%, Zr: 0.05 to 0.3 mass%, Cr: 0 in addition to the component elements. The aluminum alloy brazing sheet according to any one of claims 1 to 3, further comprising at least one selected from the group consisting of 0.05 to 0.3 mass% and V: 0.05 to 0.3 mass%. Manufacturing method . The core material includes Mg: 0.05 to 0.5 mass%, Ti 0.05 to 0.3 mass%, Zr: 0.05 to 0.3 mass%, Cr: 0.05 to 0.00 in addition to the component elements. The method for producing an aluminum alloy brazing sheet according to any one of claims 1 to 4, further comprising at least one selected from the group consisting of 3 mass% and V: 0.05 to 0.3 mass%. And aluminum alloy core and an aluminum alloy brazing sheet comprising a brazing material of Al-Si alloy which is clad on one surface of the core, a sacrificial anode material which is clad on the other surface of the core, The core material contains Si: 0.05 to 1.2 mass%, Fe: 0.05 to 1.0 mass%, Cu: 0.05 to 1.2 mass%, Mn: 0.6 to 1.8 mass%. An aluminum alloy composed of the balance Al and unavoidable impurities, wherein the brazing material contains Si: 2.5 to 13.0 mass, Fe: 0.05 to 1.0 mass%, and the balance Al and unavoidable impurities. The sacrificial anode material contains Zn: 1.0-6.0 mass%, Si: 0.05-1.5 mass%, Fe: 0.05-2.0 mass% , An aluminum alloy and the balance Al and inevitable impurities, as a metal structure of the core, the distribution density of the intermetallic compound of less than 0.01 [mu] m 0.1 [mu] m is ¹⁰ 4 ^~5 × ^{10 5} cells / ^mm 2, 0 distribution density of 1μm below the intermetallic compound or .1μm is ¹⁰ 4 ^~5 × ^{10 6} cells / ^mm 2, an aluminum alloy brazing sheet is the distribution density of the above intermetallic compound 1μm is 5 × 10 ³ cells / mm ² or more A manufacturing method of
A step of casting the core material, the brazing material and the aluminum alloy of the sacrificial anode material, a step of homogenizing the cast core material ingot, a brazing material cast on one surface of the homogenized core material ingot, and A step of cladding the sacrificial anode material cast on the other surface, a step of hot rolling the clad clad material, and a step of cold rolling the hot rolled clad material,
The homogenization step is a heating stage from heating the core material ingot to reaching the heating holding temperature, a heating holding stage for holding the core material ingot that has reached the heating holding temperature, and heating the core material ingot. A cooling step of cooling from the holding temperature, and in the heating step, the rate of temperature rise from the start of heating the core material ingot to 400 ° C. is 60 ° C./h or more, and the temperature of the core material ingot exceeds 400 ° C. The rate of temperature rise until reaching 500 ° C. is 30 ° C./h or more, and the rate of temperature rise from the temperature of the core ingot exceeding 500 ° C. until reaching the heating holding temperature is 30 ° C./h or less. In the heating and holding stage, the core material ingot is heated and held at 580 to 620 ° C. for 1 hour or more and 20 hours or less. In the cooling stage, the cooling rate from the start of cooling of the core material ingot to 500 ° C. is 30 ° C./h or less. The temperature of the core material ingot Cooling rate from below the 500 ° C. until a 400 ° C. is at 30 ° C. / h or higher,
In the middle of the cold rolling process, intermediate annealing at a temperature of 300 to 450 ° C. is performed once or more, and the final plate thickness is reached by setting the rolling rate in the final cold rolling stage to 10 to 30%. A method for producing an aluminum alloy brazing sheet . The method for producing an aluminum alloy brazing sheet according to claim 6, wherein the brazing material further contains Zn: 0.5 to 5.5 mass% in addition to the component elements. The brazing filler metal is Ti 0.05 to 0.3 mass%, Zr: 0.05 to 0.3 mass%, Cr: 0.05 to 0.3 mass%, and V: 0.05 to 0 in addition to the above component elements. The manufacturing method of the aluminum alloy brazing sheet of Claim 6 or 7 which further contains 1 or more types selected from the group which consists of .3 mass%. The sacrificial anode material includes Mn: 0.05 to 1.8 mass%, Mg: 0.5 to 3.0 mass%, Ti 0.05 to 0.3 mass%, Zr: 0.05 to 9. The composition according to claim 6, further comprising at least one selected from the group consisting of 0.3 mass%, Cr: 0.05 to 0.3 mass%, and V: 0.05 to 0.3 mass%. The manufacturing method of the aluminum alloy brazing sheet of description to term. The core material includes Mg: 0.05 to 0.5 mass%, Ti 0.05 to 0.3 mass%, Zr: 0.05 to 0.3 mass%, Cr: 0.05 to 0.00 in addition to the component elements. The method for producing an aluminum alloy brazing sheet according to any one of claims 6 to 9, further comprising at least one selected from the group consisting of 3 mass% and V: 0.05 to 0.3 mass%.