JP5576662B2 - Aluminum alloy brazing sheet and method for producing aluminum alloy brazing sheet - Google Patents

Description

  The present invention relates to an aluminum alloy brazing sheet having functions of high corrosion resistance and external brazing, and in particular, aluminum alloy brazing used for tube materials constituting automotive heat exchangers such as condensers and evaporators. It relates to the sheet.

  As a tube material of an automotive heat exchanger, an Al-Mn-based alloy such as 3003 alloy is used as a core material, and a brazing material of an Al-Si-Zn-based alloy for imparting a sacrificial anticorrosive function to the tube material on one surface. A three-layer brazing sheet is used in which the other surface is clad with a brazing material of an Al—Si alloy.

  At present, there is a demand for a brazing sheet having higher corrosion resistance. However, in the brazing sheet clad with the above-mentioned Al—Si—Zn brazing material, Zn added together with the flow of the braze flows, and brazing is performed. The amount of Zn remaining in the subsequent brazing sheet is reduced. For this reason, it is difficult to ensure corrosion resistance, which causes pitting corrosion of the tube material.

  Therefore, in order to ensure the corrosion resistance of the tube material and suppress pitting corrosion, it is necessary to add a large amount of Zn into the brazing material.

  For this reason, clad brazing material added with Zn on the external surface exposed to the corrosive environment, forming a potential difference between the brazing material and the core material, so that when pitting corrosion occurs, corrosion occurs in the surface direction of the material. A brazing sheet that has been advanced to delay penetration in the thickness direction due to pitting corrosion has been proposed. (For example, Patent Documents 1 and 2)

JP 2001-71172 A JP 2002-28800 A

  However, when a heat exchanger member using a brazing sheet is brazed, the molten brazing material may enter the core material portion and cause partial dissolution (erosion). This partial dissolution (erosion) has been a technical problem to be avoided in conventional brazing sheets containing Zn as in Patent Documents 1 and 2.

  The reason is that the eutectic part produced in the partial dissolution (erosion) part corrodes preferentially and penetrates. More specifically, Zn concentrates in the eutectic part in the partially dissolved (erosion) part, and as a result, the eutectic part becomes lower in potential compared with other solid layer parts, and preferential corrosion occurs. It is.

  In recent years, the problem of resource depletion has been taken up, but Zn, which is an element that imparts the sacrificial anticorrosion function as described above, has been targeted, and improvement in corrosion resistance by Zn-less is desired.

  Furthermore, when the brazing sheet is partially melted (erosion), Si in the external brazing material is reduced, and the liquid phase for brazing is reduced, so that there is a problem that sufficient brazing properties cannot be obtained.

  The present invention has been made paying attention to such problems, and aims to provide an aluminum alloy brazing sheet having high corrosion resistance without adding Zn and having a function of external brazing and a method for producing the same. To do.

The aluminum alloy brazing sheet according to the first aspect of the present invention for achieving the above object is:
In an aluminum alloy brazing sheet comprising a core material made of an aluminum alloy and a brazing material made of an aluminum alloy on at least one surface of the core material,
The core material has Si of 0.10 to 0.90 mass%, Fe of 0.10 to 0.60 mass%, Cu of 0.20 to 0.80 mass%, Mn of 0.6 to 1.8 mass%, and Ti of 0. 0.05 to 0.20 mass%, with the balance consisting of Al and inevitable impurities,
The brazing material contains Si of 5.0 to 12.0 mass%, Fe of 0.20 to 0.50 mass%, Na of 0.005 to 0.10 mass%, and the balance is made of Al and inevitable impurities,
When heated at a temperature of 597 to 615 ° C. for 1 to 4 minutes, an erosion part composed of a re-solidified structure of a part in which the core material is partially dissolved from the surface of the core material toward the inside is formed ,
The erosion part is formed in the entire region in contact with the brazing material of the core material at a thickness of 0.5 to 3 times the thickness of the brazing material before heating in the entire range of the heating conditions ,
The re-solidified structure contains Si, and has a eutectic structure containing Si in part.
It is characterized by that.

Moreover, the manufacturing method of the aluminum alloy brazing sheet according to the second aspect of the present invention for achieving the above-described object,
In a method for producing an aluminum alloy brazing sheet comprising: a core material made of an aluminum alloy; and a brazing material made of an aluminum alloy on at least one surface of the core material,
The core material has Si of 0.10 to 0.90 mass%, Fe of 0.10 to 0.60 mass%, Cu of 0.20 to 0.80 mass%, Mn of 0.6 to 1.8 mass%, and Ti. 0.05 to 0.20 mass%, the balance consists of Al and inevitable impurities,
The brazing material is made of an Al—Si based aluminum alloy,
Crimping the core material and the brazing material into a laminate;
Annealing the laminate at 300 to 570 ° C .;
Cooling the laminate at a cooling rate of 0.005 to 0.1 ° C./sec;
Applying a pre-strain so that the strain of the laminate is 0.5 to 5%;
It is characterized by including.

  According to the present invention, it is possible to obtain an aluminum alloy brazing sheet having high corrosion resistance and excellent brazing properties and a manufacturing method thereof without adding Zn.

It is a figure which shows typically the flat tube formed using the brazing sheet which concerns on this invention, and is a figure explaining the lamination | stacking state of a brazing sheet by notching a part of cross section. (A) is a figure which shows the photograph of the cross section which shows the state which the partial melt | dissolution (erosion) of the brazing sheet concerning this invention occurred, (b) is a figure which shows the state typically. It is a figure which shows the photograph which expanded the partial melt | dissolution (erosion) part of FIG. It is a figure which shows the photograph of the cross section of a brazing sheet, and is a figure which shows the state in which partial melt | dissolution (erosion) has not occurred. It is a figure which expands and shows the junction part of the flat tube and fin which were formed using the brazing sheet which concerns on this invention. It is a graph which shows the brazing material thickness and erosion thickness at the time of heating the brazing sheet which concerns on this invention. It is a graph which shows the brazing material thickness and erosion thickness at the time of heating the brazing sheet which concerns on this invention.

  Hereinafter, an aluminum alloy brazing sheet according to an embodiment of the present invention, a manufacturing method thereof, and a manufacturing method of a heat exchanger using the aluminum alloy brazing sheet according to the embodiment of the present invention will be described in detail.

  First, the aluminum alloy brazing sheet 10 according to the present embodiment will be described.

  The aluminum alloy brazing sheet 10 according to the present embodiment includes a core material 11 made of an aluminum alloy, an outer brazing material 12 and an inner brazing material 13 made of an aluminum alloy. As shown in FIG. 1, the aluminum alloy brazing sheet 10 is a laminate having a three-layer structure in which an outer brazing material 12 is crimped to the outer side of the core material 11 and an inner brazing material 13 is crimped to the inner side of the core material 11. In the present embodiment, the outer brazing material 12 and the inner brazing material 13 are formed of an aluminum alloy having the same composition.

(Heartwood)
The core material 11 is an aluminum alloy containing aluminum as a main component and added with the following elements.

  In the core material 11, 0.10 to 0.90 mass% of Si is added. If the Si content of the core material 11 is less than 0.10 mass%, the strength after brazing is greatly reduced. Moreover, when it adds exceeding 0.90 mass%, melting | fusing point of the core material 11 will fall, and the drooping property at the time of brazing of the brazing sheet 10 will fall.

  In the core material 11, Fe is added at 0.10 to 0.60 mass%. When Fe is added to the core material 11, it exists as an Al—Fe-based compound or an Al—Fe—Si-based compound, and has an effect of improving the strength after brazing. If it is less than 0.10 mass%, since these compounds are small, the strength after brazing is insufficient. Moreover, when it exceeds 0.60 mass%, since these compounds will increase, a cathode site will increase and the corrosion resistance of the core material 11 will fall. From the viewpoint of strength and corrosion resistance, it is more preferably 0.20 to 0.40 mass%.

  In the core material 11, 0.20 to 0.80 mass% of Cu is added. Cu is an element that improves the strength of the core material 11. If it is less than 0.20 mass%, the strength of the core material 11 cannot be improved. Moreover, when it exceeds 0.80 mass%, intergranular corrosion sensitivity will increase and corrosion resistance will be reduced. Also, when the brazing sheet is brazed and heated, the molten brazing material penetrates into the core material part and partially melts (erosion), and a re-solidified structure mainly composed of Si solid solution and a eutectic structure mainly composed of Si solid solution Produce. At this time, if it is less than 0.20 mass%, the concentration of Cu in the eutectic structure is weak, and the deterrent against the progress of pitting corrosion becomes small.

  In the core material 11, 0.6 to 1.8 mass% of Mn is added. Mn is an element that improves the strength of the core material 11. If it is less than 0.6 mass%, the strength of the core material 11 cannot be improved. On the other hand, if the Mn content exceeds 1.8 mass%, a coarse intermetallic compound is produced, so that workability and corrosion resistance are lowered.

  In the core material 11, Ti is added in an amount of 0.05 to 0.20 mass%. Ti is an element that improves the corrosion resistance of the core material 11. When Ti is contained in the core material 11, the effect of suppressing the progress of pitting corrosion in the depth direction due to Ti being deposited in the core material 11 in layers. is there. If it is less than 0.05 mass%, the corrosion resistance is not affected. On the other hand, if it exceeds 0.20 mass%, a coarse intermetallic compound is produced, so that workability and corrosion resistance are lowered.

(Al-Si brazing filler metal)
The Al—Si-based outer brazing filler metal 12 and inner brazing filler metal 13 are aluminum alloys mainly composed of aluminum and added with the following elements.

  In the outer brazing filler metal 12 and the inner brazing filler metal 13, Si is added in an amount of 5.0 to 12.0 mass%. If the amount of Si is less than 5.0 mass%, the amount of brazing material to be formed is reduced, so that the brazing property is lowered. On the other hand, if it exceeds 12.0 mass%, coarse Si is crystallized during casting, so that cracking occurs during clad rolling.

  In the outer brazing filler metal 12 and the inner brazing filler metal 13, Fe is added in an amount of 0.20 to 0.50 mass%. Fe is added to the Al—Si based brazing materials 12 and 13 to form an Al—Fe based or Al—Fe—Si based compound in the primary crystal part and the eutectic part in the brazed part. Since these compounds serve as cathode sites, they serve as starting points for occurrence of corrosion. In the above Fe addition range, the primary crystal part and the eutectic part corrode evenly, so that preferential corrosion can be suppressed. If it is less than 0.20 mass%, since there are few compounds in both the primary crystal part and the eutectic part in the brazing part, the eutectic part where the potential structure becomes lower is preferentially corroded. On the other hand, if it exceeds 0.50 mass%, the amount of Al—Fe-based or Al—Fe—Si-based compound in the eutectic portion increases, and the eutectic portion preferentially corrodes. In order to ensure the corrosion resistance of the brazed portion, it is more preferable to add at 0.20 to 0.40 mass%.

  In the outer brazing filler metal 12 and the inner brazing filler metal 13, 0.005 to 0.10 mass% of Na is added. Na is added to the Al—Si brazing filler metals 12 and 13 to finely and uniformly disperse the size of the Si particles in the Al—Si brazing filler metal, thereby suppressing the generation of coarse Si particles. Local melting can be suppressed. Although the same effect can be obtained by adding Sr, oxidation of the brazing material proceeds at the time of brazing heating, reducing the fluidity of the brazing material and reducing brazing properties. On the other hand, when Na is added, the flowability of the brazing material during brazing heating does not decrease, so that the brazing performance can be improved. If the amount is less than 0.005 mass%, the above-described effect is not exhibited, and even if the amount is added in excess of 0.10 mass%, the above-described effect is not observed.

  Moreover, Zn is mentioned as an impurity of an Al-Si type brazing material, for example. The Zn content is preferably 0.10 mass% or less.

  The aluminum alloy brazing sheet 10 described above is put into a furnace, the temperature in the furnace is set to 597 to 615 ° C., and heated for 1 to 4 minutes (min).

  As a result, as shown in FIGS. 2 (a) and 2 (b), the brazing sheet 10 has the melted brazing material invaded into the core material portion and caused partial dissolution (erosion) to form an erosion portion A having a thickness t. Is done. The erosion part A is formed on the surface of the brazing sheet with a thickness 0.5 to 3 times the thickness of the brazing material laminated on the brazing sheet 10 before heating. If the thickness of the erosion part A is less than 0.5 times the thickness of the brazing material, the anticorrosion layer for suppressing pitting corrosion is thin, so that pitting corrosion proceeds in a corrosive environment, and the thickness of the brazing sheet 10 Penetration occurs in the direction. Further, if the thickness of the erosion part A exceeds three times the thickness of the brazing filler metal, after the erosion part A is corroded and dissolved in a corrosive environment, the remaining part of the core material is slight, and therefore pitting corrosion further occurs. If it progresses, it will penetrate quickly. Moreover, unless the partial dissolution (erosion) depth is controlled as described above, a sufficient liquid phase for improving brazing cannot be formed. In addition, since erosion does not occur when the brazing material thickness is small, a predetermined brazing material thickness is required to form the erosion portion.

  Further, as shown in FIGS. 2 (a), 2 (b) and 3, the erosion part A includes a resolidified structure B mainly composed of Si solid solution and a eutectic structure C mainly composed of Si solid solution. It is configured. The re-solidified structure B mainly composed of Si solid solution is a granular portion formed in white along the surface of the brazing sheet in FIGS. 2B and 3. Further, the eutectic structure C mainly composed of Si solid solution is a portion formed between the re-solidified structure B in the vicinity of the surface layer of the brazing sheet and between the re-solidified structure B. In FIG. FIG. 3 shows a portion indicated in black.

  The brazing sheet 10 of the present embodiment is greatly different from the conventional brazing sheet having a brazing material added with Zn when heated at the above temperature and time in the following points.

  First, as shown in FIGS. 2 (a), 2 (b), and 3, the erosion part A is positively generated in a part of the core part, thereby improving the corrosion resistance. In the brazing sheet 10 of the present embodiment, since Zn is not concentrated in the eutectic structure C of the erosion part A by not adding Zn to the outer brazing filler metal 12, the potential is compared with other solid layer parts. There is no base and no preferential corrosion occurs. Further, since Cu added to the core material 11 is concentrated in the eutectic structure C of the partially dissolved (erosion) portion, it becomes noble in potential and no preferential corrosion occurs. In addition, when fin material or the like is brazed and joined, there is no Zn to be concentrated in the fillet portion, so that early preferential corrosion does not occur in the fillet portion.

  As shown in FIG. 3, the erosion part A is composed of a resolidified structure B mainly composed of Si solid solution and a eutectic structure C mainly composed of Si solid solution. Since there is no Cu concentration at the surface portion and Cu concentration is continuously generated at a portion closest to the core material 11, the re-solidified structure B itself forms a strong potential boundary layer. As a result, the progress of pitting corrosion is stopped in this boundary layer, and the pitting corrosion progresses in the planar direction in the resolidified structure B mainly composed of Si solid solution, so that pitting corrosion penetration can be suppressed.

  Furthermore, by controlling the partial erosion depth, it is possible to ensure the corrosion resistance by the re-solidified structure B. As shown in FIG. 4, when partial dissolution (erosion) does not occur, re-solidified structure B is not formed, and corrosion resistance cannot be ensured. On the other hand, when partial dissolution (erosion) occurs in a tube formed using a conventional double-sided brazing brazing sheet, the partial dissolution (erosion) depth outside the tube and partial dissolution (erosion) inside the tube ) Since the part depth was not controlled, there was no core material to remain, and Zn was concentrated in the eutectic structure, so corrosion was penetrated early.

  Furthermore, by appropriately controlling the amount of Si and the partial dissolution (erosion) depth of the brazing material, a decrease in the liquid phase mainly composed of Si for brazing can be prevented and the brazing property can be improved.

  From the above, the present invention enables pitting corrosion suppression by Zn-less, unlike the conventional sacrificial corrosion prevention system mainly composed of Zn.

  In the present embodiment, the core material 11, the outer brazing material 12, and the inner brazing material 13 have a three-layer structure in which the core material 11 and the outer brazing material 12 are in pressure bonding. It does not matter. In this embodiment, the outer brazing filler metal 12 and the inner brazing filler metal 13 are formed of the same aluminum alloy having a composition within the provisions of the present invention, but at least the outer brazing filler metal 12 only has a composition within the provisions of the present invention. That's fine. The inner brazing material 13 may be an aluminum alloy having a composition outside the scope of the present invention, and the inner brazing material 13 itself may not be present.

  Next, the manufacturing method of the aluminum alloy brazing sheet of this embodiment is demonstrated.

  The ingots of the core material 11 and the Al—Si-based outer brazing material 12 and inner brazing material 13 are cast by a DC (Direct Hill) casting method, a continuous casting method or the like. The outer brazing filler metal 12 and the inner brazing filler metal 13 are formed into a plate shape having a predetermined thickness by carrying out hot rolling at 500 ° C. after chamfering the ingot of the Al—Si brazing filler metal. To do. The core material 11 is formed by subjecting the core material ingot to a homogenization treatment at 520 ° C. for 6 hours and chamfering to a thickness of 40 mm. Thereafter, the Al—Si brazing material plate, the core material ingot, and the Al—Si brazing material plate are combined in this order, hot-rolled at 480 ° C., pressure-bonded, and a laminate having a thickness of 3.5 mm. And This laminate is cold-rolled to a predetermined thickness.

  Next, the laminated body formed as described above is tempered to form the aluminum alloy brazing sheet 10 of the present embodiment. The tempering is performed to facilitate partial dissolution (erosion) during brazing. In order for partial dissolution (erosion) to occur, it is basically important that subgrains remain in the core material crystals, and Si contained in the brazing material diffuses into the subcrystal grains to dissolve the core material. As long as it is a point, it is sufficient if it is tempered to achieve it. In particular, in order to actively generate partial dissolution (erosion), annealing after rolling completely anneals the material at 300 to 570 ° C., and then cools the cooling rate at 0.005 to 0.1 ° C./sec. Further, pre-strain is applied so that the strain becomes 0.5% to 5%.

  When the annealing temperature is lower than 300 ° C., it is not completely softened. Further, when the annealing temperature is higher than 570 ° C., melting of the core material occurs due to diffusion of Si contained in the brazing material. Further, when the cooling rate is lower than 0.005 ° C./sec, it becomes an unsuitable condition for operation. On the other hand, if the pre-strain is less than 0.5% or exceeds 5%, partial dissolution (erosion) hardly occurs.

  For example, as a means of tempering, cold rolling after hot rolling is performed, and after sufficient softening is achieved in the annealing treatment, strain treatment for easily causing partial melting (erosion) is appropriately performed. . The above means do not particularly limit the present invention.

  The aluminum alloy brazing sheet of this embodiment is mainly applied to brazing using a fluoride-based flux. The thickness of the brazing sheet is not particularly limited, but is preferably 0.1 mm or more and 0.5 mm or less for the tube material, and 0.8 mm or more for the tank material of the heat exchanger. 2 mm or less is preferable.

  Next, the manufacturing method of the heat exchanger of the present invention will be described by taking as an example a case where a heat exchanger is manufactured using a flat tube which is a preferable use example of the brazing sheet 10 of the present embodiment.

  First, the flat tube 20 as shown in FIG. 1 is formed using the brazing sheet 10 of this embodiment. The flat tube 20 is used as a member of a heat exchanger such as a condenser.

  Next, as shown in FIG. 5, the flat tubes 20 and the fins 30 made of aluminum alloy are alternately stacked one by one. Therefore, heat. Brazing heating is performed for 1 to 4 minutes (min) by setting the temperature in the furnace to 597 to 615 ° C.

  At the time of the brazing heating, the brazing sheet 10 of the present embodiment used for the flat tube 20 is, as shown in FIG. 2, the molten brazing material enters the core material part and causes partial dissolution (erosion), The erosion part A is formed.

  Here, the thickness of the erosion part A is controlled to 0.5 to 3 times the thickness of the brazing material laminated on the brazing sheet 10 before heating. As described above, when the thickness of the erosion part A is less than 0.5 times the thickness of the brazing material, pitting corrosion is likely to proceed, and when exceeding 3 times, penetration occurs when pitting corrosion proceeds. Because it will end up. Moreover, unless the partial dissolution (erosion) depth is controlled as described above, a sufficient liquid phase for improving brazing cannot be formed.

  In addition, as shown in FIG. 3, the erosion part A is composed of a resolidified structure B mainly composed of Si solid solution and a eutectic structure C mainly composed of Si solid solution.

  Next, the heat exchanger brazed and heated as described above is cooled. Thereafter, when the melted outer brazing filler metal 12 is solidified, as shown in FIG. 5, a joint portion X is formed, the outside of the flat tube 20 and the fin 30 are joined, and a heat exchanger is formed.

  With the above, a heat exchanger having high corrosion resistance is formed using the brazing sheet 10 to which Zn is not added. Moreover, since the brazing sheet 10 has an external brazing function, a heat exchanger in which the flat tubes 20 and the fins 30 are appropriately joined is formed.

  Examples of the present invention will be described below in comparison with comparative examples. These examples show one embodiment of the present invention, and the present invention is not limited to these examples.

Example 1
The core material of the present invention composition (samples 1 to 9) and the Al—Si brazing material shown in Table 1 were each cast by direct current (DC) casting to produce an ingot. In the Al—Si brazing filler metal, after chamfering, it was rolled into a plate shape by hot rolling at 500 ° C. The ingot for the core material was homogenized at 520 ° C. for 6 hours and chamfered to a thickness of 40 mm. The Al—Si brazing material plate, the core material ingot, and the Al—Si brazing material plate are stacked in this order and hot-rolled at 480 ° C. to obtain a three-layer clad material having a thickness of 3.5 mm. This was cold-rolled to a predetermined thickness, then annealed at 360 ° C. for 3 hours, cooled at the cooling rate shown in Table 2, and then strained with a tension leveler to give a final thickness of 0.4 mm. It was. In this way, test materials A1 to A9, B1 to B9, and BB1 to BB9 were obtained. In addition, the composition value of Table 1 is a value measured from the brazing material and the core material after casting by an emission spectroscopic analyzer.

(Comparative Example 1)
The core composition of the present invention-specified composition (samples 1 to 9) shown in Table 1 and the alloy composition of the Al—Si brazing material are similarly performed until hot rolling in Example 1, and this is cold-rolled to a predetermined thickness. And then annealed at 360 ° C. for 3 hours. Thereafter, cooling at a cooling rate shown in Table 2 and straining with a tension leveler were performed, and the final plate thickness was set to 0.4 mm. As described above, test materials C1 to C9, D1 to D9, E1 to E9, and F1 to F9 were obtained.

(Comparative Example 2)
The alloy composition of the core material and the Al—Si brazing filler metal of the composition outside the specification of the present invention shown in Table 1 (samples 10 to 19) is similarly performed until the hot rolling of Example 1, and this is cold rolled to a predetermined thickness. And then annealed at 360 ° C. for 3 hours. Thereafter, Samples 10 to 17 were cooled at a cooling rate shown in Table 2 and strained with a tension leveler, and the final thickness was 0.4 mm. Thus, test materials B10 to B17 were obtained. In addition, about the samples 18 and 19, since the healthy brazing sheet material was not able to be manufactured, cooling and distortion provision were not performed.

(Conventional example 1)
The alloy composition of the core material, the Al—Si—Zn-based brazing material, and the Al—Si-based brazing material with the composition outside of the present invention (sample 20) shown in Table 1 was similarly performed until hot rolling in Example 1, Cold rolling to a predetermined thickness was performed, followed by annealing at 360 ° C. for 3 hours. Thereafter, cooling was performed under the cooling conditions shown in Table 2, and the final thickness was set to 0.4 mm. Thus, a test material C20 was obtained.

  Each of the obtained brazing sheets was subjected to various evaluations on manufacturability, tensile strength after brazing, erosion thickness, brazing property, and corrosion resistance, and the results obtained are shown in Tables 3 and 4.

(Manufacturability)
When a brazing sheet with a clad rate of 10% is manufactured by combining each of the Al-Si brazing filler metal and the core material, ◎ indicates that a healthy brazing sheet can be manufactured, and ○ indicates that processing was difficult but manufacturing was possible. In the case where cracking occurred during casting, or the case where the clad rate could not be controlled, x was marked.

(Tensile strength after brazing)
A JIS No. 5 test piece was cut out from each aluminum alloy brazing sheet, heated in a nitrogen atmosphere at 600 ° C. for 3 minutes, and a tensile test was performed. The tensile strength after brazing is 140 MPa or more, and 140 MPa or less is x.

(Erosion thickness)
A test piece having a width of 20 mm and a length of 150 mm was cut out from each aluminum alloy brazing sheet, heated at 600 ° C. for 3 minutes in a nitrogen atmosphere, and the thickness of the erosion part from the brazing part on one side was observed from the cross-sectional observation of the plate. Was measured. 0.5 to 3 times the thickness of the brazing material laminated on the brazing sheet before heating was marked as ◎, and less than 0.5 times and over 3 times as x.

(Brassability evaluation)
(1) Fin / tube junction length As shown in FIG. 5, the flat tubes 20 and the fins 30 were alternately stacked one by one to create a mini-core. The flat tube 20 was made using each aluminum alloy brazing sheet and formed with an Al—Si brazing material as the outside. As the fin material, a JIS 3003 alloy bare material having a thickness of 0.08 mm was used, and corrugation was performed so that the fin pitch was 3 mm, the length of the fin after corrugation was 10 mm, and the number of joint points was 20. A KF-AlF ₃ type flux (KAlF ₄ or the like) powder was applied to the mini-core and dried, followed by brazing heating at 600 ° C. for 3 minutes in a nitrogen atmosphere. In the minicore subjected to the brazing heating described above, the joint portion between the fin 30 and the flat tube 20 was examined.

  The length L formed by the joint portion X of the fin 30 made of the bare material and the flat tube 20 made of the brazing sheet was measured as shown in FIG. The case where the average value of the measured junction length was 500 μm or more and 650 μm or less was rated as ◎, and the case where the average value was less than 500 μm was rated as x.

(2) Suspension From each aluminum alloy brazing sheet, a test piece having a width of 22 mm and a length of 60 mm is cut out, heated with one end of the brazing sheet protruding 50 mm and the other end fixed with metal fittings, and the brazing sheet hangs down. Was measured and used as the amount of drooping. The case where the drooping amount was 15 mm or less was marked with ◎, and the case where the drooping amount was larger than 15 mm was marked with ×.

(3) Local melting of core material From each aluminum alloy brazing sheet, a test piece having a width of 20 mm and a length of 150 mm was cut out, heated in a nitrogen atmosphere at 600 ° C. for 3 minutes, and the cross section of the plate material was observed, and the brazing material In the case where there is no local dissolution in the core material by Si contained in, ◎, and in some cases, it was marked as ×.

(Corrosion resistance)
As shown in FIG. 5, a SWAAT test was conducted as a corrosion resistance evaluation in a mini-core in which flat tubes made using each aluminum alloy brazing sheet and fins made of a bare material were alternately stacked and brazed and heated. Carried out. The SWAAT test was conducted using artificial seawater (ASTM D 1141) defined by ASTM G85-A3. The test period was 1000 hours. In the minicore after the SWAAT test, the pitting corrosion depth of the tube portion Y between the fins 20 shown in FIG. 5 was measured.
The maximum pitting corrosion depth of the tube portion between the fins 20 is less than 60 μm, and 60 μm or more is x.

  As shown in Tables 3 and 4, as a result of various tests, in Example 1 of the present invention, the present invention was evaluated for manufacturability, tensile strength after brazing heating, erosion thickness, brazing property, and corrosion resistance. Although it was suitable for use in the environment where it was applied, in Comparative Examples 1 and 2, an unsuitable result appeared in the environment where the present invention was used. The same was true for Conventional Example 1.

(Example 2)
The core material and the Al—Si brazing material having the composition of Sample 1 shown in Table 1 were each DC casted to produce an ingot. In the Al—Si brazing filler metal, after chamfering, it was rolled into a plate shape by hot rolling at 500 ° C. The ingot for the core material was homogenized at 520 ° C. for 6 hours and chamfered to a thickness of 40 mm. The Al—Si brazing material plate, the core material ingot, and the Al—Si brazing material plate are stacked in this order and hot-rolled at 480 ° C. to obtain a three-layer clad material having a thickness of 3.5 mm. This was cold-rolled to a predetermined thickness, then annealed at 360 ° C. for 3 hours, cooled at 0.01 ° C./sec, and then applied with a strain of 0.5% with a tension leveler. The final plate thickness was 100 μm to 500 μm, 800 μm to 1200 μm, and test materials G1 to G10 were obtained.

  A test piece having a width of 20 mm and a length of 150 mm was cut out from the test materials G1 to G10, heated in a nitrogen atmosphere at 600 ° C. for 1 to 4 minutes, and the erosion portion was observed from the brazing material portion on one side from the cross-sectional observation of the plate material. The thickness was measured. The obtained results are shown in Table 5, FIG. 6 and FIG.

As shown in Table 5, in Example 2 of the present invention, when heating was performed for 1 to 4 minutes (min), the one-side erosion thickness (t2) / one-side brazing material thickness (t1) was 0.5 to The erosion thickness suitable for the present invention was 3.0. However, in less than 1 minute, a sufficient erosion thickness was not formed, and even when heated for more than 4 minutes, the erosion thickness did not change much.
Similar results were obtained for test materials to which strains of 4% and 5% were applied with a tension leveler. Moreover, also in the samples 2 to 9 shown in Table 1, the same results as above were obtained when the test materials were prepared under the same conditions and heated under the same conditions.

DESCRIPTION OF SYMBOLS 10 Brazing sheet 11 Core material 12 Outer brazing material 13 Inner brazing material 20 Flat tube 30 Fin

Claims (2)

In an aluminum alloy brazing sheet comprising a core material made of an aluminum alloy and a brazing material made of an aluminum alloy on at least one surface of the core material,
The core material has Si of 0.10 to 0.90 mass%, Fe of 0.10 to 0.60 mass%, Cu of 0.20 to 0.80 mass%, Mn of 0.6 to 1.8 mass%, and Ti of 0. 0.05 to 0.20 mass%, with the balance consisting of Al and inevitable impurities,
The brazing material contains Si of 5.0 to 12.0 mass%, Fe of 0.20 to 0.50 mass%, Na of 0.005 to 0.10 mass%, and the balance is made of Al and inevitable impurities,
When heated at a temperature of 597 to 615 ° C. for 1 to 4 minutes, an erosion part composed of a re-solidified structure of a part in which the core material is partially dissolved from the surface of the core material toward the inside is formed ,
The erosion part is formed in the entire region in contact with the brazing material of the core material at a thickness of 0.5 to 3 times the thickness of the brazing material before heating in the entire range of the heating conditions ,
The re-solidified structure contains Si, and has a eutectic structure containing Si in part.
An aluminum alloy brazing sheet characterized by that. In a method for producing an aluminum alloy brazing sheet comprising: a core material made of an aluminum alloy; and a brazing material made of an aluminum alloy on at least one surface of the core material,
The core material has Si of 0.10 to 0.90 mass%, Fe of 0.10 to 0.60 mass%, Cu of 0.20 to 0.80 mass%, Mn of 0.6 to 1.8 mass%, and Ti. 0.05 to 0.20 mass%, the balance consists of Al and inevitable impurities,
The brazing material is made of an Al—Si based aluminum alloy,
Crimping the core material and the brazing material into a laminate;
Annealing the laminate at 300 to 570 ° C .;
Cooling the laminate at a cooling rate of 0.005 to 0.1 ° C./sec;
Applying a pre-strain so that the strain of the laminate is 0.5 to 5%;
The manufacturing method of the aluminum alloy brazing sheet characterized by including this.