JP2018197395A - Aluminum alloy blazing sheet - Google Patents

Abstract

To provide an aluminum alloy blazing sheet which allows a reduction of a curvature radius of a shoulder R part without rupture of the shoulder R part of a tube folded part and has excellent solderability between the shoulder R part of the tube folded part and a flat part.SOLUTION: In an aluminum alloy blazing sheet, at least one side of a core material is cladded with a soldering material, or one side of the core material is cladded with the soldering material and the other side is cladded with a sacrificial material. The aluminum alloy blazing sheet has a breaking elongation of 0.5% or greater and a work hardening coefficient n value smaller than 0.05.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an aluminum alloy brazing sheet used for a heat exchanger for automobiles and the like.

  Conventionally, as a material for a heat exchanger such as an automobile, a brazing sheet (hereinafter referred to simply as “Al alloy”) made of an aluminum alloy (hereinafter sometimes simply referred to as “Al alloy”) in which a brazing material and a sacrificial material are disposed on one or both sides of a core material. Simply called “brazing sheet”).

  In automotive heat exchangers such as radiators and heater cores, a brazing sheet having a three-layer structure (brazing material / core material / sacrificial material) is used as a tube material. That is, the tube is formed by bending the brazing sheet so that the sacrificial material of the brazing sheet is on the inside and the cross-sectional shape is a B shape or the like. The formed tube is assembled to the actual machine core, for example, in combination with other flat plate-like parts. Thereafter, each component is brazed and joined by brazing. At this time, the molten brazing material flows into the gap portion surrounded by the shoulder R portion of the tube bent portion and the flat part, thereby filling the gap portion with the brazing material. When used as a heat exchanger, the cooling water flows inside the actual machine core, that is, the inside of the tube. Therefore, it is necessary that the gap portion or the like is brazed so as to be sufficiently filled with the brazing material.

  Conventionally, in order to improve brazing properties, attempts have been made to improve the fluidity of brazing materials by changing the composition of brazing materials (for example, Patent Literature 1 and Patent Literature 2), and each of the core material and sacrificial anode material. An attempt to specify Vickers hardness (for example, Patent Document 3) has been disclosed.

JP 2011-12327 A JP 2008-308724 A JP 2010-18872 A

However, the conventional aluminum alloy brazing sheet does not improve the bendability of the brazing sheet itself, and does not necessarily lead to a sufficient improvement in brazing.
In particular, when the volume of the gap part surrounded by the shoulder R part of the tube bent part and the flat part is large, the aluminum alloy brazing sheet is not filled with the brazing material sufficiently, and the gap space remains, resulting in poor brazing. Occurs. Therefore, there has been a demand for a technique for reducing the volume of the gap and improving the brazability.

  The present invention has been made in view of such a situation. The present invention can reduce the radius of curvature of the shoulder R portion without breaking the shoulder R portion of the tube bent portion, and is excellent in brazing between the shoulder R portion of the tube bent portion and a flat part. Another object is to provide an aluminum alloy brazing sheet.

  As a result of investigations, the present inventors have found that it is effective to reduce the radius of curvature of the tube bending shoulder as much as possible in order to reduce the space volume of the gap. Further, it has been found that it is effective to make the work hardening index n value less than 0.05 in order to reduce the radius of curvature of the tube bending shoulder. Furthermore, it has been found that it is effective to increase the breaking elongation of the brazing sheet to 0.5% or more in order to prevent the tube bending shoulder from breaking.

  That is, the aluminum alloy brazing sheet of the present invention is an aluminum alloy brazing sheet in which a brazing material is clad on at least one surface of a core material, has an elongation at break of 0.5% or more, and a work hardening index n value of 0. It is less than 05.

  The aluminum alloy brazing sheet of the present invention is an aluminum alloy brazing sheet in which a brazing material is clad on one surface of a core material and a sacrificial material is clad on the other surface of the core material, and the elongation at break is 0.5%. The work hardening index n value is less than 0.05.

  Since it is an aluminum alloy brazing sheet having such characteristics, it is possible to reduce the radius of curvature of the tube bending shoulder, and the brazing material in the gap between the shoulder R of the tube bending and the flat part. Can be sufficiently filled.

  In the aluminum alloy brazing sheet of the present invention, the core material is any one of 2000 series, 3000 series, 5000 series, and 6000 series aluminum alloys. By using such a core material, it can be used satisfactorily as an aluminum alloy brazing sheet used in automobile heat exchangers and the like.

  The aluminum alloy brazing sheet according to the present invention can reduce the radius of curvature of the shoulder R portion without breaking the shoulder R portion of the tube bent portion. Excellent brazing performance.

It is sectional drawing for demonstrating the 90 degree bending test method by the bending press machine of the aluminum alloy brazing sheet of this invention. It is a perspective view of the test piece for brazing property evaluation using the aluminum alloy brazing sheet of the present invention. It is sectional drawing for demonstrating the evaluation site | part of the brazing property of the aluminum alloy brazing sheet of this invention. (B) is sectional drawing to which the part enclosed with the square of the broken line of (a) was expanded.

  Hereinafter, the form for implementing the aluminum alloy brazing sheet of this invention is demonstrated in detail.

The first embodiment of the aluminum alloy brazing sheet of the present invention is an aluminum alloy brazing sheet in which a brazing material is clad on at least one surface of a core material. The second embodiment of the aluminum alloy brazing sheet of the present invention is an aluminum alloy brazing sheet in which a brazing material is clad on one surface of a core material and a sacrificial material is clad on the other surface of the core material. In any of the embodiments, the breaking elongation of the aluminum alloy brazing sheet is 0.5% or more, and the work hardening index n value is less than 0.05.
Each configuration will be described below.

(Heartwood)
As the aluminum alloy constituting the core material of the aluminum alloy brazing sheet of the present invention, any of 2000 series, 3000 series, 5000 series, and 6000 series aluminum alloys can be used. These aluminum alloys can be sufficiently used in terms of physical properties as aluminum alloy brazing sheets used for applications such as automotive heat exchangers. The core material is preferably 40 μm or more in thickness. When the core material thickness is less than 40 μm, the strength after brazing becomes insufficient.

  As a 2000 series aluminum alloy, Cu: 2.0-4.0 mass% is contained, Si: 1.5 mass% or less, Mn: 2.0 mass% or less, Mg: 2.0 as needed. Further containing at least one of mass% or less, Ti: 0.35 mass% or less, Fe: 1.0 mass% or less, Cr: 0.5 mass% or less, Zr: 0.5 mass% or less, and the balance It preferably consists of Al and inevitable impurities. Further, regarding the inclusion of elements other than Cu, Si, Mn, Mg, Ti, Fe, Cr, Zr, and Al, each is less than 0.1% by mass, and is acceptable if the total is less than 0.3% by mass Is done.

  As a 3000 series aluminum alloy, Mn: 0.5-2.0 mass% is contained, Si: 0.05-1.5 mass%, Cu: less than 2.0 mass%, Mg: 1.0% by mass or less, Ti: 0.35% by mass or less, Fe: 1.0% by mass or less, Cr: 0.5% by mass or less, Zr: 0.5% by mass or less The balance is preferably made of Al and inevitable impurities. In addition, regarding the inclusion of elements other than Mn, Si, Cu, Mg, Ti, Fe, Cr, Zr, and Al, each is less than 0.1% by mass, and is acceptable if the total is less than 0.3% by mass Is done.

  As a 5000 series aluminum alloy, Mg: 0.5-4.0 mass% is contained, Si: Less than 0.3 mass%, Mn: Less than 0.5 mass%, Cu: 1.5 as needed. Further containing at least one of mass% or less, Ti: 0.35 mass% or less, Fe: 1.0 mass% or less, Cr: 0.5 mass% or less, Zr: 0.5 mass% or less, and the balance It preferably consists of Al and inevitable impurities. In addition, regarding the inclusion of elements other than Mg, Si, Mn, Cu, Ti, Fe, Cr, Zr, and Al, each is less than 0.1% by mass, and is acceptable if the total is less than 0.3% by mass Is done.

  As a 6000 series aluminum alloy, Si: 0.3-2.0 mass%, Mg: 0.3-2.0 mass% is contained, Mn: less than 0.5 mass%, Cu: It further contains one or more of less than 2.0 mass%, Ti: 0.35 mass% or less, Fe: 1.0 mass% or less, Cr: 0.5 mass% or less, Zr: 0.5 mass% or less. The balance is preferably made of Al and inevitable impurities. In addition, regarding the inclusion of elements other than Si, Mg, Mn, Cu, Ti, Fe, Cr, Zr, and Al, each is less than 0.1% by mass, and is acceptable if the total is less than 0.3% by mass Is done.

(Brazing material)
As the aluminum alloy constituting the brazing material of the aluminum alloy brazing sheet of the present invention, 4000 series aluminum alloys such as JIS-regulated 4343, 4045, 4047, and 4005 that have been widely used in the past can be used.

  Among these, an Al—Si based alloy containing 4.0 to 13.5% by mass of Si is desirable. When the content of Si is less than 4.0% by mass, the liquid phase ratio becomes low and brazing tends to be insufficient. On the other hand, if it exceeds 13.5% by mass, coarse primary crystal Si is likely to be generated, and cracks are likely to occur during molding.

  Moreover, in order to make the brazing material have a lower potential and to give the brazing material a sacrificial anticorrosive effect, an Al—Si alloy containing 4.0 to 13.5% by mass of Si is added to Zn in an amount of 0.5 to 7. You may add 0 mass%. In this case, if Zn is less than 0.5% by mass, the degree of potential baseing is small, and the sacrificial anticorrosive effect tends to be insufficient. If Zn exceeds 7.0% by mass, Zn is likely to concentrate in the braze (fillet) portion formed at the joint with the other member after the brazing heat, and the fillet portion is likely to be preferentially corroded.

  In the brazing sheet according to the present invention, the brazing material is preferably clad with a thickness of 5 to 50 μm per one side. If the thickness of the brazing material is less than 5 μm, the absolute amount of the brazing is insufficient and the brazing property may be lowered. On the other hand, when the brazing filler metal thickness exceeds 50 μm, the flow amount of brazing becomes excessive, and part of the brazing material may erode and erosion of the core material may occur. In addition, when it is set as the aluminum alloy brazing sheet provided with the brazing material on both surfaces, the brazing material on each surface may be an aluminum alloy having the same component or different.

(Sacrificial material)
In the aluminum alloy brazing sheet according to the present invention, the brazing material is provided on one surface of the core material, and the sacrificial material is clad on the other surface, thereby improving the corrosion resistance from the surface side. . When producing a brazed joint structure with a brazing sheet provided with such a sacrificial material, the part is molded so that the surface provided with the sacrificial material is on the corrosive environment side.

  As the aluminum alloy constituting the sacrificial material of the aluminum alloy brazing sheet of the present invention, a 7000 series aluminum alloy containing Zn can be used. Furthermore, Si, Mn, etc. may be contained. The sacrificial material is preferably 5 to 50 μm in thickness. If the thickness of the sacrificial material is less than 5 μm, there is a concern that sacrificial corrosion protection becomes insufficient and sufficient corrosion resistance cannot be secured. On the other hand, if the thickness of the sacrificial material exceeds 50 μm, the core material ratio becomes small, and the strength after brazing may be insufficient.

  As the sacrificial material, for example, an Al—Zn alloy containing 1.0 to 6.0 mass% of Zn is used. Zn has an effect of lowering the potential of the sacrificial material and providing a sacrificial anticorrosive effect. If the Zn content is less than 1.0% by mass, the sacrificial anticorrosive effect tends to be insufficient. If the Zn content exceeds 6.0% by mass, the potential difference between the sacrificial material and the core material increases, and the consumption rate of the sacrificial material increases. There is a concern that sufficient corrosion resistance cannot be secured.

Further, as the sacrificial material, an Al—Si—Zn alloy containing 0.1 to 1.0 mass% of Si and 1.0 to 6.0 mass% of Zn may be used. Si functions to increase the tensile strength of the sacrificial material. If the Si content is less than 0.1% by mass, the effect of improving the tensile strength will be insufficient, and if it exceeds 1.0% by mass, the solidus temperature of the sacrificial material will decrease and the brazing heat will increase. There is a concern of melting at times. If the Zn content is less than 1.0% by mass, the sacrificial anticorrosive effect is insufficient, and if it exceeds 6.0% by mass, the potential difference between the sacrificial material and the core material increases, and the consumption rate of the sacrificial material increases. There is a concern that sufficient corrosion resistance cannot be secured.
Note that the sacrificial material is not limited to these, and an Al—Mg—Si—Zn alloy, an Al—Si—Mn—Zn alloy, an Al—Mg—Zn alloy, or the like may be used.

Next, the characteristics of the aluminum alloy brazing sheet of the present invention will be described.
(Elongation at break: 0.5% or more)
Elongation at break was taken from JIS Z2201 No. 5 test piece so that the tensile direction was parallel to the rolling direction from the brazing sheet, at room temperature and at a crosshead speed of 5 mm / min in accordance with the provisions of JIS Z2241. A tensile test is performed at a constant speed until the test piece breaks, and measurement is performed from the obtained SS curve.
When the breaking elongation of the aluminum alloy brazing sheet is less than 0.5%, cracking is likely to occur during tube forming of the material. Therefore, in the present invention, it is necessary to make the breaking elongation of the aluminum alloy brazing sheet 0.5% or more. The elongation at break can be controlled by conditions such as finish cold rolling described later.

(Work hardening index n value: less than 0.05)
The work hardening index n value is a characteristic value that is a measure of moldability. The work hardening index n value is measured by the method described below.
A No. 5 test piece of JIS Z2201 is collected from the test piece of the brazing sheet so that the tensile direction is parallel to the rolling direction, and a tensile test is performed at room temperature in accordance with the provisions of JIS Z2241. The crosshead speed at this time is 5 mm / min, and is performed at a constant speed until the test piece breaks. Calculate true strain and true stress, plot on a logarithmic scale with strain on the horizontal axis and stress on the vertical axis, and measure the slope of the straight line connecting the 0.2% proof stress point to the tensile strength point. The curing index was n.

  When the n value of the aluminum alloy brazing sheet is 0.05 or more, the material is easy to work harden, and the strain of plastic deformation is dispersed in a wide range of the tube bent portion. As a result, the radius of curvature of the shoulder R portion at the tube bent portion is increased, and is surrounded by the shoulder R portion of the tube bent portion and a flat part (meaning that at least the contact surface with the tube is flat). Since the gap becomes large, brazing defects are likely to occur. Therefore, the work hardening index n value needs to be less than 0.05. A more preferred range is less than 0.04. The work hardening index n value can be controlled by the condition of finish cold rolling, as will be described later in the method for producing a brazing sheet.

  If the thickness of the aluminum alloy brazing sheet of the present invention exceeds 1.0 mm, the radius of curvature of the shoulder R portion at the tube bent portion becomes large and brazing failure is likely to occur. Therefore, the finally obtained aluminum alloy brazing The sheet thickness is preferably 1.0 mm or less. A more preferable plate thickness is 0.3 mm or less, and a more preferable plate thickness is 0.2 mm or less.

(Brazing sheet manufacturing method)
Next, the manufacturing method of the aluminum alloy brazing sheet of this invention is demonstrated. The brazing sheet of the present invention can be produced by the following production method as an example of a typical production method.
First, an aluminum alloy for a core material, an aluminum alloy for a sacrificial material, and an aluminum alloy for a brazing material are melted and cast by a continuous casting method to produce an ingot. The ingot is subjected to chamfering (surface smoothing treatment) and homogenization heat treatment to produce a core material ingot (core material member), a sacrificial material ingot, and a brazing material ingot. Thereafter, the ingot for sacrificial material and the ingot for brazing material are each hot-rolled to a predetermined thickness to obtain a sacrificial material member and a brazing material member.

Next, in the first embodiment, a brazing material member is superposed on one surface side of the core material member, and heat treatment (reheating) is performed on the superposed material, followed by pressure bonding by hot rolling to obtain a plate material. . In the second embodiment, the sacrificial material member is superposed on one surface side of the core material member, the brazing material member is superposed on the other surface side, and heat treatment (reheating) is performed on the superposed material. A plate is formed by pressure bonding by rolling. Thereafter, these plate materials are subjected to cold rolling and intermediate annealing, and further subjected to finish cold rolling.
The ingot for the core material does not need to be homogenized. The ingot for the brazing material and the ingot for the sacrificial material are not subjected to hot rolling, and the thickness is adjusted by face milling. Each may be a brazing material member and a sacrificial material member. Moreover, it is not necessary to heat-treat the laminated material.

  Conditions for the above-described casting, homogenization heat treatment, hot rolling, cold rolling, intermediate annealing, and finish cold rolling of each material can be performed according to a known ordinary method. However, in order to set the breaking elongation and work hardening index n value, which are characteristic characteristics of the aluminum alloy brazing sheet of the present invention, to predetermined values, as described below, the conditions in the finish cold rolling process are specified. It is preferable to adopt the following conditions.

(Rolling ratio of finish cold rolling: 15% or more and 90% or less)
If the rolling rate in the finish cold rolling step is less than 15%, the material is easily work-hardened, and the n value tends to be 0.05 or more. Moreover, when the rolling rate in a finish cold rolling process exceeds 90%, it will become easy to work harden | cure a material and n value will become 0.05 or more easily. Therefore, the rolling rate of finish cold rolling is preferably 15% or more and 90% or less.

(Winding temperature for each pass of finish cold rolling: 80 ° C or higher and 150 ° C or lower)
The cold rolling process is a process performed at room temperature, but the material temperature after rolling rises due to processing heat generation. Although the detailed mechanism is not clear, it thinks as follows. In the finish cold rolling process, if the winding temperature of one-pass cold rolling is less than 80 ° C., the accumulated amount of strain introduced by processing increases, so the elongation becomes small and the material becomes difficult to mold. easy. On the other hand, when the winding temperature of one-pass cold rolling exceeds 150 ° C., material recovery proceeds, and the n value tends to be 0.05 or more. Therefore, the winding temperature for each pass in the finish cold rolling step is preferably 80 ° C. or higher and 150 ° C. or lower. The winding temperature was measured by applying a contact-type thermometer to the end face of the coil immediately after winding.

  In general, heat exchangers such as condensers, evaporators, and intercoolers mounted on automobiles are assembled by alternately and repeatedly combining flat tubular tubes constituting fluid passages and fins formed by corrugated plate material to collect the fluid passages. Thus, it has the structure assembled by fitting a tube to the plate which press-molded the board | plate material. When these parts are assembled and subjected to brazing addition heat, the tubes and fins and the tubes and plates are joined together to manufacture a heat exchanger. Parts are joined to each other by filling a connecting portion between the parts with a brazing material (melting solder) melted by brazing additional heat to form a brazing reservoir (fillet). The aluminum alloy brazing sheet of the present invention can be applied to these tubes and the like.

Next, the present invention will be described in more detail based on examples.
<Production of test material>
A core material having the composition shown in Table 1 (core materials No. 1 to 12), a brazing material of an Al—Si alloy with a Si content of 10% by mass, and an Al—Zn with a Zn content of 4.0% by mass The alloy sacrificial materials were each agglomerated by DC casting and each side was chamfered to a desired thickness. The brazing material and the sacrificial material were each subjected to homogenization treatment, combined in the order of brazing material-core material-sacrificial material, heated at 530 ° C. × 4 h, and then hot-rolled to a thickness of 3.0 mm. The clad rate of the brazing material and the sacrificial material was 15%. After hot rolling, cold rolling and intermediate annealing at 350 ° C. × 2 h were performed, and then finish cold rolling was performed under the conditions shown in Table 2 to obtain a plate material having a plate thickness of 0.25 mm (sample No. 2). 1-16, 19-22). In Table 1, the metal element indicated by “-” is not added.

  In addition, a core material having the composition shown in Table 1 (core material No. 12) and an Al-Si alloy brazing material having a Si content of 10% by mass are each agglomerated by DC casting, and both sides are faced to a desired thickness I sharpened it. The brazing material was subjected to homogenization treatment, combined with the brazing material and the core material, heated at 530 ° C. for 4 hours, and then hot-rolled to a thickness of 3.0 mm. The clad rate of the brazing material was 15%. After hot rolling, cold rolling and intermediate annealing at 350 ° C. × 2 h were performed, and then finish cold rolling was performed under the conditions shown in Table 2 to obtain a plate material having a plate thickness of 0.25 mm (sample No. 2). 17, 18, 23-26).

  Next, the plate material prepared above is used as a test material (No. 1 to 26), and the n value of the test material, the elongation at break, and the radius of curvature of the shoulder R portion of the bent portion after the 90 ° bending test by a bending press machine. The brazing properties were measured and evaluated by the methods shown below, and the results are shown in Table 2.

<Work hardening index n value and elongation at break>
A No. 5 test piece of JIS Z2201 was sampled from the test material so that the tensile direction was parallel to the rolling direction, and a tensile test was performed at room temperature in accordance with the provisions of JIS Z2241. The crosshead speed at this time was 5 mm / min, and was performed at a constant speed until the test piece broke. The work hardening index n value is calculated from the true strain and the true stress, plotted on a logarithmic scale with strain on the horizontal axis and stress on the vertical axis, and is a straight line connecting from the 0.2% proof stress point to the tensile strength point. The gradient was measured and taken as the n value. On the other hand, the breaking elongation was evaluated as 0 for 0.5% or more and x for less than 0.5%.

<Curved radius of shoulder R of tube bent part>
FIG. 1 is a cross-sectional view for explaining a 90 ° bending test method using an aluminum alloy brazing sheet bending press according to the present invention.
First, a 30 W × 70 L plate is cut out from the test material so that the longitudinal direction is perpendicular to the rolling direction. As shown in FIG. 1, after attaching the cut plate to the lower mold side, open a gap of (plate thickness + 0.05 mm) and move the upper mold up and down to make the end of the plate about 2 mm wide Then, it was bent so as to have an angle of about 90 °. The radius of curvature R ₀ of the corner portion of the upper mold is approximately ₀ mm. At this time, the folding line was parallel to the short direction of the test material and parallel to the rolling direction. Further, in the cross-sectional view of FIG. 1, the rolling direction of the test material was set to be perpendicular to the bending direction. Thereafter, the vicinity of the shoulder R portion (the broken line circle in FIG. 1) is cut out, embedded in resin, the cross section is polished to the center in the plate width direction, the cross section is observed with an optical microscope, and the outside of the shoulder R portion of the bent portion is observed. The curvature radius of the surface was measured. Those having a radius of curvature of 450 μm or less were evaluated as very good (（), those exceeding 450 μm and 500 μm or less being good (◯), and those exceeding 500 μm being defective (×). Moreover, the crack generate | occur | produced at the time of a 90 degree bending test, and the thing which could not measure a curvature radius was described as "a crack."

<Brassability by mini-core>
FIG. 2 is a perspective view of a test piece for brazing evaluation using the aluminum alloy brazing sheet of the present invention. Moreover, FIG. 3 is sectional drawing for demonstrating the evaluation site | part of the brazing property of the aluminum alloy brazing sheet of this invention. Fig.3 (a) is sectional drawing in the AA surface when the test piece for brazing property evaluation of FIG. 2 is seen from the left side. FIG. 3B is an enlarged cross-sectional view of a portion surrounded by a broken-line square in FIG.
Each specimen was cut into a predetermined size so that the longitudinal direction was parallel to the rolling direction, and was pressed so as to have the shape shown in FIG. 2 and FIG. At this time, the brazing material surface was on the outside. As a plate, a rolled sheet made of 3003 aluminum alloy having a plate thickness of 1.5 mm was produced and cut into a predetermined size. As a fin, a rolled sheet made of 3003 aluminum alloy having a thickness of 0.1 mm was produced and pressed so as to be as shown in FIG. After applying 10 g / mm ² each of flux (Morita Chemical Co., Ltd., Flux FL-7) to the plate and tube, each member is assembled as shown in FIG. 2 and held at 600 ° C. for 3 minutes in a nitrogen gas atmosphere. Thus, brazing addition heat was applied. Then, in order to observe the cross section of the joint part of a plate and a tube (the part enclosed with the broken-line circle | round | yen of FIG.3 (b)), it embedded in resin and grind | polished to the predetermined position. The observation positions in the brazed state were two locations, 0.5 mm and 1.0 mm from the fin-side plate surface. Each brazed joint state is visually observed. If there are no cavities in two places, ◎ if there is a cavity in one place and there is no cavity in the other place. Judged. The case where cracks occurred during the 90 ° bending test and the brazing ability could not be evaluated was described as “−”.

  As shown in Tables 1 and 2, an aluminum alloy brazing sheet (test material Nos. 1 to 16) satisfying the provision of claim 2 of the present invention and an aluminum alloy brazing satisfying the provision of claim 1 of the present invention. The sheets (test materials No. 17 and 18) had a small radius of curvature of the shoulder R portion of 500 μm or less, and were excellent in brazeability.

  On the other hand, aluminum alloy brazing sheets (test materials No. 19, 20, 22, 24, and 26) that do not satisfy the provisions of claim 1 or claim 2 of the present invention have a work hardening index n value of 0.05 or more. The curvature radius of the shoulder R portion was over 500 μm, and the brazeability was inferior. Since the aluminum alloy brazing sheets (test materials No. 21 and 25) that do not satisfy the provisions of claim 1 or claim 2 of the present invention have a breaking elongation of less than 0.5%, they are bent by 90 ° using a bending press. During the test, cracks occurred and the processability was poor.

Claims (3)

An aluminum alloy brazing sheet in which a brazing material is clad on at least one surface of a core material,
An aluminum alloy brazing sheet having an elongation at break of 0.5% or more and a work hardening index n value of less than 0.05. An aluminum alloy brazing sheet in which a brazing material is clad on one surface of a core material and a sacrificial material is clad on the other surface of the core material,
An aluminum alloy brazing sheet having an elongation at break of 0.5% or more and a work hardening index n value of less than 0.05.   The aluminum alloy brazing sheet according to claim 1 or 2, wherein the core material is any one of 2000 series, 3000 series, 5000 series and 6000 series aluminum alloys.

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