Aluminum alloy brazing sheet for heat exchanger

Abstract

An aluminum alloy brazing sheet for a heat exchanger includes a three-layer material in which a brazing material layer, an intermediate layer, and a core material are cladded and stacked, the intermediate layer is formed of an aluminum alloy which can include Mn, Si, Fe, and Cu, with the balance being Al and inevitable impurities, the core material is formed of an aluminum alloy which can include Si, Fe, Cu, and Mn, with the balance being Al and inevitable impurities, and the brazing material layer is formed of an aluminum alloy including Si, with the balance being Al and inevitable impurities.

Claims

1. An aluminum alloy brazing sheet for a heat exchanger, the aluminum alloy brazing sheet comprising a three-layer material in which an air-side surface of a core material is cladded and stacked with an intermediate layer and a brazing material layer in this order from the core material side, wherein the intermediate layer is formed of an aluminum alloy consisting of Mn of 0.2 mass % or more and less than 0.35 mass %, Si of 0.6 mass % or less, Fe of 0.7 mass % or less, and Cu of 0.1 mass % or less, and optionally one or more of Ti of 0.3 mass % or less, Zr of 0.3 mass % or less, and Cr of 0.3 mass % or less, with the balance being Al and inevitable impurities, the core material is formed of an aluminum alloy including Si of 1.2 mass % or less, Fe of 1.0 mass % or less, Cu of 0.3 mass % or more and 1.0 mass % or less, and Mn of 0.5 mass % or more and 2.0 mass % or less, with the balance being Al and inevitable impurities, the brazing material layer is formed of an aluminum alloy including Si of 4 mass % or more and 13 mass % or less, with the balance being Al and inevitable impurities, and the intermediate layer has a clad ratio of 5 to 30% and the brazing material layer has a clad ratio of 5 to 20%.

2. The aluminum alloy brazing sheet for a heat exchanger according to claim 1, wherein the aluminum alloy forming the core material further includes one or two or more of Ti of 0.3 mass % or less, Zr of 0.3 mass % or less, and Cr of 0.3 mass % or less.

3. The aluminum alloy brazing sheet for a heat exchanger according to claim 1, wherein the aluminum alloy forming the brazing material layer further includes Sr of 0.1 mass % or less.

4. A method for manufacturing an aluminum alloy brazing sheet for a heat exchanger comprising stacking an aluminum alloy ingot for a brazing material layer formed of an aluminum alloy including Si of 4 to 13 mass %, with the balance being Al and inevitable impurities, an aluminum alloy ingot for an intermediate layer formed on an aluminum alloy consisting of Mn of 0.2 mass % or more and less than 0.35 mass %, Si of 0.6 mass % or less, Fe of 0.7 mass % or less, and Cu of 0.1 mass % or less, and optionally one or more of Ti of 0.3 mass % or less, Zr of 0.3 mass % or less, and Cr of 0.3 mass % or less, with the balance being Al and inevitable impurities, and an aluminum alloy ingot for a core material formed of an aluminum alloy including Si of 1.2 mass % or less, Fe of 1.0 mass % or less, Cu of 0.3 to 1.0 mass %, and Mn of 0.5 to 2.0 mass %, with the balance being Al and inevitable impurities in this order, and subjecting to clad hot rolling and cold rolling, wherein at least the aluminum alloy ingot for the core material is subjected to homogenization, no annealing is performed during the cold rolling, and a recrystallization annealing is performed only after the cold rolling is performed to acquire a final thickness, and the intermediate layer has a clad ratio of 5 to 30% and the brazing material layer has a clad ratio of 5 to 20%.

5. A method for manufacturing an aluminum alloy brazing sheet for a heat exchanger comprising stacking an aluminum alloy ingot for a brazing material layer formed of an aluminum alloy including Si of 4 to 13 mass %, with the balance being Al and inevitable impurities, an aluminum alloy ingot for an intermediate layer formed of an aluminum alloy consisting of Mn of 0.2 mass % or more and less than 0.35 mass %, Si of 0.6 mass % or less, Fe of 0.7 mass % or less, and Cu of 0.1 mass % or less, and optionally one or more of Ti of 0.3 mass % or less, Zr of 0.3 mass % or less, and Cr of 0.3 mass % or less, with the balance being Al and inevitable impurities, and an aluminum alloy ingot for a core material formed of an aluminum alloy including Si of 1.2 mass % or less, Fe of 1.0 mass % or less, Cu of 0.3 to 1.0 mass %, and Mn of 0.5 to 2.0 mass %, with the balance being Al and inevitable impurities in this order, and subjecting to clad hot rolling and cold rolling, wherein at least the aluminum alloy ingot for the core material is subjected to homogenization, no annealing is performed during the cold rolling, and a recovery annealing is performed only after the cold rolling is performed to acquire a final thickness, and the intermediate layer has a clad ratio of 5 to 30% and the brazing material layer has a clad ratio of 5 to 20%.

6. A method for manufacturing an aluminum alloy brazing sheet for a heat exchanger comprising stacking an aluminum alloy ingot for a brazing material layer formed of an aluminum alloy including Si of 4 to 13 mass %, with the balance being Al and inevitable impurities, an aluminum alloy ingot for an intermediate layer formed of an aluminum alloy consisting of Mn of 0.2 mass % or more and less than 0.35 mass %, Si of 0.6 mass % or less, Fe of 0.7 mass % or less, and Cu of 0.1 mass % or less, and optionally one or more of Ti of 0.3 mass % or less, Zr of 0.3 mass % or less, and Cr of 0.3 mass % or less, with the balance being Al and inevitable impurities, and an aluminum alloy ingot for a core material formed of an aluminum alloy including Si of 1.2 mass % or less, Fe of 1.0 mass % or less, Cu of 0.3 to 1.0 mass %, and Mn of 0.5 to 2.0 mass %, with the balance being Al and inevitable impurities in this order, and subjecting to clad hot rolling and cold rolling, wherein at least the aluminum alloy ingot for the core material is subjected to homogenization, a recrystallization annealing or a recovery annealing is performed during the cold rolling, and another cold rolling is performed to acquire a final thickness after the recrystallization annealing or the recovery annealing, and the intermediate layer has a clad ratio of 5 to 30% and the brazing material layer has a clad ratio of 5 to 20%.

7. A method for manufacturing an aluminum alloy brazing sheet for a heat exchanger comprising stacking an aluminum alloy ingot for a brazing material layer formed of an aluminum alloy including Si of 4 to 13 mass %, with the balance being Al and inevitable impurities, an aluminum alloy ingot for an intermediate layer formed of an aluminum alloy consisting of Mn of 0.2 mass % or more and less than 0.35 mass %, Si of 0.6 mass % or less, Fe of 0.7 mass % or less, and Cu of 0.1 mass % or less, and optionally one or more of Ti of 0.3 mass % or less, Zr of 0.3 mass % or less, and Cr of 0.3 mass % or less, with the balance being Al and inevitable impurities, and an aluminum alloy ingot for a core material formed of an aluminum alloy including Si of 1.2 mass % or less, Fe of 1.0 mass % or less, Cu of 0.3 to 1.0 mass %, and Mn of 0.5 to 2.0 mass %, with the balance being Al and inevitable impurities in this order, and subjecting to clad hot rolling and cold rolling, wherein at least the aluminum alloy ingot for the core material is subjected to homogenization, a recovery annealing is performed during another cold rolling, the cold rolling is performed to acquire a final thickness after the recovery annealing, and another recovery annealing is performed after the another cold rolling, and the intermediate layer has a clad ratio of 5 to 30% and the brazing material layer has a clad ratio of 5 to 20%.

8. The method for manufacturing an aluminum alloy brazing sheet for a heat exchanger according to claim 4, wherein the aluminum alloy ingot for the intermediate layer formed of the aluminum alloy further includes one or two or more of Ti of 0.3 mass % or less, Zr of 0.3 mass % or less, and Cr of 0.3 mass % or less.

9. The method for manufacturing an aluminum alloy brazing sheet for a heat exchanger according to claim 4, wherein the aluminum alloy ingot for the core material formed of the aluminum alloy further includes one or two or more of Ti of 0.3 mass % or less, Zr of 0.3 mass % or less, and Cr of 0.3 mass % or less.

10. The method for manufacturing an aluminum alloy brazing sheet for a heat exchanger according to claim 4, wherein the aluminum alloy ingot for the brazing material layer formed of the aluminum alloy further includes Sr of 0.1 mass % or less.

Description

EXAMPLES

(1) To manufacture a tube member forming the coolant passage of a heat exchanger, aluminum alloys for an intermediate layer listed in Table 1, aluminum alloys for a core material listed in Table 2, and aluminum alloys for a brazing material layer listed in Table 3 were casted. Aluminum alloy ingots for the intermediate layer and aluminum alloy ingots for the core material were subjected to homogenization in which the ingots were retained at 600° C. for 10 hours.

(2) Thereafter, the ingot surface of each of the aluminum alloys was subjected to facing. The aluminum alloy ingots for the brazing material layer and the aluminum alloy ingots for the intermediate layer were subjected to hot rolling to predetermined thicknesses, and the ingots were combined and subjected to clad hot rolling to form the three-layer clad materials listed in Table 4.

(3) Thereafter, each of the materials was subjected to cold rolling to a thickness of 0.3 mm without performing annealing during the rolling, and recrystallized at final annealing to perform O temper and manufacture the aluminum alloy brazing sheet for a heat exchanger.

(4) Each of the acquired aluminum alloy brazing sheets for heat exchangers has a structure in which the brazing material, the intermediate layer, and the core material are arranged from the external surface side.

(5) The following Evaluations 1 to 3 were performed using these aluminum alloy brazing sheets.

(6) Evaluation 1

(7) Table 5 lists manufacturing results of these materials. In the casting and the rolling, the materials that were successfully manufactured in good state without any problem are provided with the mark “O”, the materials that were manufactured with some difficulty are provided with the mark “Δ”, and the materials manufacturing of which ended in failure are provided with the mark “x”.

(8) Evaluation 2

(9) Each of the materials that could be manufactured in Evaluation 1 was formed into a tube of an ordinary drawn-cup type having an ordinary drawn-cup type shape in a portion in which the brazing material layers were bonded. In the tube, in a portion in which the core material sides were bonded in an ordinary drawn-cup shape, bending was performed to fold back the brazing material layer sides such that the brazing material layers were bonded. Thereafter, the tube was assembled with members, such as an ordinary outer bare fin and an ordinary clad inner fin, to form a drawn-cup heat exchanger by brazing heating. A flux liquid mixture obtained by suspending Nocolok flux in water was applied to the assembled heat exchanger with a spray and thereafter dried. As the brazing heating conditions, each of the structures was heated to 600° C. at average temperature increase speed of 50° C./min in a nitrogen gas atmosphere, and maintained for three minutes, and thereafter the temperature was decreased to room temperature. Thereafter, the external appearance thereof was observed and leakage test was performed. Table 6 lists results thereof. The structures without any problem in external appearance and without leakage are provided with the mark “O”, and the structures in which local melting and/or leakage occurred are provided with the mark “x”.

(10) Evaluation 3

(11) In the same manner, each of the materials that could be manufactured in Evaluation 1 was subjected to brazing heating with a single plate, and subjected to SWAAT test provided under ASTM-G85 A3. The brazing heating conditions were the same conditions as those of Evaluation 2. The evaluation surface in SWAAT was the external surface side, and the test time was 1,000 h. Table 7 lists results of measurement of the maximum corrosion depth after the test. The structures with the maximum corrosion depth of 0.1 mm or less are provided with the mark “O”, the structures with the maximum corrosion depth more than 0.1 mm and 0.2 mm or less are provided with the mark “Δ”, and the structures with the maximum corrosion depth more than 0.2 mm and reaching penetration are provided with the mark “x”. Only in Evaluation 3, a three-layer material serving as a conventional material (test material No. 26) was evaluated as a comparative example. The three-layer material has the same thickness as those of the examples, an A4343/A3003/A4343 structure, and a 10% clad ratio for both surfaces.

(12) TABLE-US-00001 TABLE 1 No. Si Fe Cu Mn Ti Sr Zr 1A 0.1 0.2 0.02 0.3 0 0 0 1B 0.6 0.7 0.1 0.34 0 0 0 1C 0.1 0.2 0.02 0.2 0 0 0 1D 0.1 0.2 0.02 0.3 0.15 0 0 1E 0.1 0.2 0.02 0.3 0 0 0.15 1F 0.1 0.2 0.02 0.3 0.15 0 0.15 1a 0.7 0.8 0.2 0.4 0 0 0 1b 0.1 0.2 0.02 0.1 0 0 0

(13) TABLE-US-00002 TABLE 2 No. Si Fe Cu Mn Ti Sr Zr 2A 0.2 0.2 0.5 1.2 0 0 0 2B 1.2 1.0 1.0 2.0 0 0 0 2C 0.2 0.2 0.3 0.5 0 0 0 2D 0.2 0.2 0.5 1.2 0.15 0 0 2E 0.2 0.2 0.5 1.2 0 0 0.15 2F 0.2 0.2 0.5 1.2 0.15 0 0.15 2a 1.4 1.5 1.2 2.5 0 0 0 2b 0.2 0.2 0.2 0.4 0 0 0

(14) TABLE-US-00003 TABLE 3 No. Si Fe Cu Mn Ti Sr Zr 3A 7.5 0.2 0 0 0 0 0 3B 13 0.2 0 0 0 0 0 3C 4 0.2 0 0 0 0 0 3D 7.5 0.2 0 0 0 0.03 0 3a 14 0.2 0 0 0 0 0 3b 3 0.2 0 0 0 0 0

(15) TABLE-US-00004 TABLE 4 External Brazing Intermediate Core Material Layer Material No. Alloy Clad Ratio Alloy Clad Ratio Alloy Examples 1 3A 10 1A 15 2A 2 3A 10 1D 15 2A 3 3A 10 1E 15 2A 4 3A 10 1F 15 2A 5 3A 10 1A 15 2D 6 3A 10 1A 15 2E 7 3A 10 1A 15 2F 8 3A 10 1F 15 2F 9 3A 10 1B 15 2B 10 3A 10 1B 15 2C 11 3A 10 1C 15 2B 12 3A 10 1C 15 2C 13 3B 10 1A 15 2A 14 3C 10 1A 15 2A Comparative 15 3A 10 1a 15 2A Examples 16 3A 10 1b 15 2A 17 3A 10 1A 15 2a 18 3A 10 1A 15 2b 19 3a 10 1A 15 2A 20 3b 10 1A 15 2A 21 3A 10 1a 15 2b 22 3A 4 1A 15 2A 23 3A 25 1A 15 2A 24 3A 10 1A 3 2A 25 3A 10 1A 35 2A

(16) TABLE-US-00005 TABLE 5 External Brazing Intermediate Core Material Layer Material Thickness No. Alloy Clad Ratio Alloy Clad Ratio Alloy (mm) Result Determination Examples 1 3A 10 1A 15 2A 0.3 Good ∘ 2 3A 10 1D 15 2A 0.3 Good ∘ 3 3A 10 1E 15 2A 0.3 Good ∘ 4 3A 10 1F 15 2A 0.3 Good ∘ 5 3A 10 1A 15 2D 0.3 Good ∘ 6 3A 10 1A 15 2E 0.3 Good ∘ 7 3A 10 1A 15 2F 0.3 Good ∘ 8 3A 10 1F 15 2F 0.3 Good ∘ 9 3A 10 1B 15 2B 0.3 Good ∘ 10 3A 10 1B 15 2C 0.3 Good ∘ 11 3A 10 1C 15 2B 0.3 Good ∘ 12 3A 10 1C 15 2C 0.3 Good ∘ 13 3B 10 1A 15 2A 0.3 Good ∘ 14 3C 10 1A 15 2A 0.3 Good ∘ Comparative 15 3A 10 1a 15 2A 0.3 Good ∘ Examples 16 3A 10 1b 15 2A 0.3 Clad rolling was x impossible 17 3A 10 1A 15 2a 0.3 Crack in casting, x clad rolling was impossible 18 3A 10 1A 15 2b 0.3 Good ∘ 19 3a 10 1A 15 2A 0.3 Good ∘ 20 3b 10 1A 15 2A 0.3 Good ∘ 21 3A 10 1a 15 2b 0.3 Good ∘ 22 3A 4 1A 15 2A 0.3 Clad rolling was Δ possible (difficult) 23 3A 25 1A 15 2A 0.3 Clad rolling was x impossible 24 3A 10 1A 3 2A 0.3 Clad rolling was Δ possible (difficult) 25 3A 10 1A 35 2A 0.3 Clad rolling was x impossible

(17) TABLE-US-00006 TABLE 6 External Brazing Intermediate Core Material Layer Material Thickness No. Alloy Clad Ratio Alloy Clad Ratio Alloy (mm) Result Determination Examples 1 3A 10 1A 15 2A 0.3 Good ∘ 2 3A 10 1D 15 2A 0.3 Good ∘ 3 3A 10 1E 15 2A 0.3 Good ∘ 4 3A 10 1F 15 2A 0.3 Good ∘ 5 3A 10 1A 15 2D 0.3 Good ∘ 6 3A 10 1A 15 2E 0.3 Good ∘ 7 3A 10 1A 15 2F 0.3 Good ∘ 8 3A 10 1F 15 2F 0.3 Good ∘ 9 3A 10 1B 15 2B 0.3 Good ∘ 10 3A 10 1B 15 2C 0.3 Good ∘ 11 3A 10 1C 15 2B 0.3 Good ∘ 12 3A 10 1C 15 2C 0.3 Good ∘ 13 3B 10 1A 15 2A 0.3 Good ∘ 14 3C 10 1A 15 2A 0.3 Good ∘ Comparative 15 3A 10 1a 15 2A 0.3 Good ∘ Examples 16 3A 10 1b 15 2A 0.3 No evaluation — (Manufacturing of material was impossible) 17 3A 10 1A 15 2a 0.3 No evaluation — (Manufacturing of material was impossible) 18 3A 10 1A 15 2b 0.3 Good ∘ 19 3a 10 1A 15 2A 0.3 With local x melting 20 3b 10 1A 15 2A 0.3 With brazing x leakage 21 3A 10 1a 15 2b 0.3 Good ∘ 22 3A 4 1A 15 2A 0.3 With brazing x leakage 23 3A 25 1A 15 2A 0.3 No evaluation — (Manufacturing of material was impossible) 24 3A 10 1A 3 2A 0.3 Good ∘ 25 3A 10 1A 35 2A 0.3 No evaluation — (Manufacturing of material was impossible)

(18) TABLE-US-00007 TABLE 7 External Brazing Intermediate Core Maximum Material Layer Material Thickness Corrosion Depth No. Alloy Clad Ratio Alloy Clad Ratio Alloy (mm) (mm) Determination Examples 1 3A 10 1A 15 2A 0.3 0.075 ∘ 2 3A 10 1D 15 2A 0.3 0.07 ∘ 3 3A 10 1E 15 2A 0.3 0.07 ∘ 4 3A 10 1F 15 2A 0.3 0.065 ∘ 5 3A 10 1A 15 2D 0.3 0.075 ∘ 6 3A 10 1A 15 2E 0.3 0.075 ∘ 7 3A 10 1A 15 2F 0.3 0.075 ∘ 8 3A 10 1F 15 2F 0.3 0.065 ∘ 9 3A 10 1B 15 2B 0.3 0.075 ∘ 10 3A 10 1B 15 2C 0.3 0.08 ∘ 11 3A 10 1C 15 2B 0.3 0.07 ∘ 12 3A 10 1C 15 2C 0.3 0.075 ∘ 13 3B 10 1A 15 2A 0.3 0.07 ∘ 14 3C 10 1A 15 2A 0.3 0.08 ∘ Comparative 15 3A 10 1a 15 2A 0.3 0.2 Δ Examples 16 3A 10 1b 15 2A 0.3 No evaluation — (Manufacturing of material was impossible) 17 3A 10 1A 15 2a 0.3 No evaluation — (Manufacturing of material was impossible) 18 3A 10 1A 15 2b 0.3 0.15 Δ 19 3a 10 1A 15 2A 0.3 0.07 ∘ 20 3b 10 1A 15 2A 0.3 0.08 ∘ 21 3A 10 1a 15 2b 0.3 0.3 x (Penetration) 22 3A 4 1A 15 2A 0.3 0.07 ∘ 23 3A 25 1A 15 2A 0.3 No evaluation — (Manufacturing of material was impossible) 24 3A 10 1A 3 2A 0.3 0.18 Δ 25 3A 10 1A 35 2A 0.3 No evaluation — (Manufacturing of malerial was impossible) 26 A4343 10 — — A3003 0.3 0.3 x (Penetration)

(19) The following are results of Evaluations 1 to 3.

(20) With respect to the manufacturing results of the three-layer clad materials, each of the materials of Examples exhibited good manufacturability. By contrast, in the materials of Comparative Examples, manufacturing of the materials of Nos. 16, 17, 23, and 25 was impossible because failure in bonding and/or cracks occurred in clad rolling. Cracks in some of the core materials occurred in casting in the material of No. 17. The materials of Nos. 22 and 24 had difficulty in clad rolling, but manufacturing thereof succeeded in the end.

(21) With respect to results of brazing of the heat exchangers, each of the materials of Examples exhibited good brazability. By contrast, in the materials of Comparative Examples, local melting occurred in the material of No. 19, and leakage occurred in leakage test after brazing in the materials of Nos. 20 and 22.

(22) With respect to the SWAAT test, each of the materials of the examples exhibited the maximum corrosion depth of 0.1 mm or less, and the maximum corrosion depth was substantially limited to a corrosion depth up to the total thickness of the brazing material of the external surface side and the intermediate layer. This fact suggests that the structures are in the sacrificial corrosion resistance period even after 1,000 h has passed, and the structures exhibited good corrosion resistance. By contrast, in the materials of Comparative Examples, the materials of Nos. 15, 18, and 24 exhibited a corrosion resistance more than 0.1 mm and 0.2 mm or less. It is considered that each of the materials had insufficient difference in potential between the intermediate layer and the core material, and the sufficient sacrificial anode effect was not sufficiently acquired. In addition, penetration occurred in the material of No. 21. It is considered that this was caused by a smaller difference in potential and acquisition of little sacrificial anode effect. Penetration also occurred in the three-layer material of No. 26 evaluated and compared as the conventional material. This has proved that corrosion resistance is improved by securing sufficient difference in potential between the intermediate layer and the core material even with the three-layer material.