Aluminum alloy clad material and heat exchanger that includes tube obtained by forming the clad material

Abstract

An aluminum alloy clad material includes a core material, an inner cladding material, and a sacrificial anode material, one side of the core material being clad with the inner cladding material, the other side of the core material being clad with the sacrificial anode material, the core material being formed of an AlMn alloy that includes 0.6 to 2.0 mass % of Mn and 0.4 mass % or less of Cu, with the balance being aluminum and unavoidable impurities, the inner cladding material being formed of an AlMnCu alloy that includes 0.6 to 2.0 mass % of Mn and 0.2 to 1.5 mass % of Cu, with the balance being aluminum and unavoidable impurities, and the sacrificial anode material being formed of an AlZn alloy that includes 0.5 to 10.0 mass % of Zn, with the balance being aluminum and unavoidable impurities.

Claims

1. An aluminum alloy clad material comprising a core material, an inner cladding material, and a sacrificial anode material, one side of the core material being clad with the inner cladding material, the other side of the core material being clad with the sacrificial anode material, the core material being formed of an AlMn alloy that consists of 0.6 to 2.0 mass % of Mn and 0.4 mass % or less of Cu, optionally, one or more of 0.01 to 0.3 mass % of Ti, 1.5 mass % or less of Si and 0.7 mass % or less of Fe, with the balance being aluminum and unavoidable impurities, the inner cladding material being formed of an AlMnCu alloy that comprises 0.6 to 2.0 mass % of Mn and 0.2 to 1.5 mass % of Cu, with the balance being aluminum and unavoidable impurities, and the sacrificial anode material being formed of an AlZn alloy that comprises 0.5 to 10.0 mass % of Zn, with the balance being aluminum and unavoidable impurities.

2. The aluminum alloy clad material according to claim 1, wherein the core material further contains one or more of 0.01 to 0.3 mass % of Ti, 1.5 mass % or less of Si and 0.7 mass % or less of Fe.

3. The aluminum alloy clad material according to claim 1, wherein the inner cladding material further comprises one or more of 0.01 to 0.3 mass % of Ti, 1.5 mass % or less of Si and 0.7 mass % or less of Fe.

4. The aluminum alloy clad material according to claim 1, wherein the sacrificial anode material further comprises 1.0 to 4.0 mass % of Zn, and one or more of 1.5 mass % or less of Si, 0.7 mass % or less of Fe, and 1.5 mass % or less of Mn.

5. The aluminum alloy clad material according to claim 1, wherein the core material further contains 0.4 mass % or less of Cu so that the Cu content in the core material is lower than the Cu content in the inner cladding material by 0.2 mass % or more.

6. The aluminum alloy clad material according to claim 2, wherein the inner cladding material further comprises one or more of 0.01 to 0.3 mass % of Ti, 1.5 mass % or less of Si and 0.7 mass % or less of Fe.

7. The aluminum alloy clad material according to claim 2, wherein the sacrificial anode material further comprises 1.0 to 4.0 mass % of Zn, and one or more of 1.5 mass % or less of Si, 0.7 mass % or less of Fe, and 1.5 mass % or less of Mn.

8. The aluminum alloy clad material according to claim 2, wherein the core material further contains 0.4 mass % or less of Cu so that the Cu content in the core material is lower than the Cu content in the inner cladding material by 0.2 mass % or more.

9. The aluminum alloy clad material according to claim 3, wherein the sacrificial anode material further comprises 1.0 to 4.0 mass % of Zn, and one or more of 1.5 mass % or less of Si, 0.7 mass % or less of Fe, and 1.5 mass % or less of Mn.

10. The aluminum alloy clad material according to claim 3, wherein the core material further contains 0.4 mass % or less of Cu so that the Cu content in the core material is lower than the Cu content in the inner cladding material by 0.2 mass % or more.

11. The aluminum alloy clad material according to claim 4, wherein the core material further contains 0.4 mass % or less of Cu so that the Cu content in the core material is lower than the Cu content in the inner cladding material by 0.2 mass % or more.

12. The aluminum alloy clad material according to claim 6, wherein the sacrificial anode material further comprises 1.0 to 4.0 mass % of Zn, and one or more of 1.5 mass % or less of Si, 0.7 mass % or less of Fe, and 1.5 mass % or less of Mn.

13. The aluminum alloy clad material according to claim 6, wherein the core material further contains 0.4 mass % or less of Cu so that the Cu content in the core material is lower than the Cu content in the inner cladding material by 0.2 mass % or more.

14. The aluminum alloy clad material according to claim 7, wherein the core material further contains 0.4 mass % or less of Cu so that the Cu content in the core material is lower than the Cu content in the inner cladding material by 0.2 mass % or more.

15. The aluminum alloy clad material according to claim 9, wherein the core material further contains 0.4 mass % or less of Cu so that the Cu content in the core material is lower than the Cu content in the inner cladding material by 0.2 mass % or more.

16. The aluminum alloy clad material according to claim 12, wherein the core material further contains 0.4 mass % or less of Cu so that the Cu content in the core material is lower than the Cu content in the inner cladding material by 0.2 mass % or more.

17. A heat exchanger produced by forming the aluminum alloy clad material according to claim 1 into a tube so that the inner cladding material defines a refrigerant passage, and the sacrificial anode material comes in contact with the atmosphere, assembling an aluminum fin with the tube, and brazing the aluminum fin and the tube.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIG. 1 is a cross-sectional view illustrating an example of a heat exchanger tube obtained by forming an aluminum alloy clad material according to one embodiment of the invention.

(2) FIG. 2 is a cross-sectional view illustrating another example of a heat exchanger tube obtained by forming an aluminum alloy clad material according to one embodiment of the invention.

(3) FIG. 3 is a view illustrating the diffusion state of Zn from a sacrificial anode material (AlZn alloy) after brazing, the diffusion state of Cu from a core material (AlMnCu-based alloy) after brazing, and the potential distribution.

(4) FIG. 4 is a view illustrating the diffusion state of Zn from a sacrificial anode material (AlZn alloy) after brazing, the diffusion state of Cu from a core material (AlMnCu-based alloy) and an inner cladding material layer after brazing, and the potential distribution.

DESCRIPTION OF EMBODIMENTS

(5) An aluminum alloy clad material according to one embodiment of the invention has a three-layer structure that includes a core material, a sacrificial anode material, and an inner cladding material that is higher in potential than the core material, one side of the core material being clad with the inner cladding material, and the other side of the core material being clad with the sacrificial anode material. When the aluminum alloy clad material is formed into a tube so that the inner cladding material defines a refrigerant passage, and the sacrificial anode material comes in contact with the atmosphere, and is assembled into a heat exchanger, the core material exhibits a sacrificial anode effect on the inner cladding material, and the sacrificial anode material and the core material function as a sacrificial anode layer with respect to the inner cladding material (i.e., the thickness of the sacrificial anode layer increases). Since the inner cladding material that has a higher potential remains even when most of the sacrificial anode material and the core material are consumed due to corrosion, it is possible to suppress the occurrence of a through-hole, and improve the corrosion resistance of the outer side (that comes in contact with the atmosphere).

(6) The core material is formed of an AlMn alloy that includes 0.6 to 2.0% of Mn and 0.4% or less of Cu, with the balance being aluminum and unavoidable impurities, the inner cladding material is formed of an AlMnCu alloy that includes 0.6 to 2.0% of Mn and 0.2 to 1.5% of Cu, with the balance being aluminum and unavoidable impurities, and the sacrificial anode material is formed of an AlZn alloy that includes 0.5 to 10.0% of Zn, with the balance being aluminum and unavoidable impurities.

(7) The core material may include either or both of 1.5% or less of Si and 0.7% or less of Fe, and may include 0.01 to 0.3% of Ti. The inner cladding material may include either or both of 1.5% or less of Si and 0.7% or less of Fe, and may include 0.01 to 0.3% of Ti. The sacrificial anode material may include one or more of 1.5% or less of Si, 0.7% or less of Fe, and 1.5% or less of Mn. The core material may include 0.4% or less of Cu so that the Cu content in the core material is lower than the Cu content in the inner cladding material by 0.2% or more.

(8) The effects of each alloy component included in the sacrificial anode material, the core material, and the inner cladding material, and the reasons for which the content of each alloy component is limited as described above, are described below.

(9) Sacrificial Anode Material

(10) Zn

(11) Zn included in the sacrificial anode material increases the potential of the sacrificial anode material. Zn is added to the sacrificial anode material in order to adjust the balance in potential with the core material and the inner cladding material. The Zn content is preferably 0.5 to 10.0%. If the Zn content is less than 0.5%, a sufficient effect may not be obtained. If the Zn content exceeds 10.0%, the self-corrosion rate may increase, and the corrosion-proof lifetime may decrease. The Zn content is more preferably 1.0 to 7.0%, and still more preferably 1.0 to 4.0%.

(12) Si

(13) Si improves the strength of the sacrificial anode material. The Si content is preferably 1.5% or less. If the Si content exceeds 1.5%, the self-corrosion rate may increase. The Si content is more preferably 0.5% or less. If the Si content is less than 0.05%, the effect of improving the strength of the sacrificial anode material may be insufficient.

(14) Fe

(15) Fe improves the strength of the sacrificial anode material. The Fe content is preferably 0.7% or less. If the Fe content exceeds 0.7%, the self-corrosion rate may increase. If the Fe content is less than 0.05%, the effect of improving the strength of the sacrificial anode material may be insufficient.

(16) Mn

(17) Mn improves the strength of the sacrificial anode material. The Mn content is preferably 1.5% or less. If the Mn content exceeds 1.5%, the self-corrosion rate may increase. The Mn content is more preferably 0.5% or less. If the Mn content is less than 0.1%, the effect of improving the strength of the sacrificial anode material may be insufficient. Note that the advantageous effects of the invention are not impaired even if the sacrificial anode material includes 0.3% or less of In, 0.3% or less of Sn, 0.3% or less of Ti, 0.3% or less of V, 0.3% or less of Cr, 0.3% or less of Zr, and 0.3% or less of B.

(18) Core Material

(19) Mn

(20) Mn improves the strength of the core material. The Mn content is preferably 0.6 to 2.0%. If the Mn content is less than 0.6%, a sufficient effect may not be obtained. If the Mn content exceeds 2.0%, it may be difficult to roll the material. The Mn content is more preferably 1.0 to 2.0%.

(21) Si

(22) Si improves the strength of the core material. The Si content is preferably 1.5% or less. If the Si content exceeds 1.5%, the melting point of the core material may decrease, and the core material may be easily melted during brazing. The Si content is more preferably 0.8% or less. If the Si content is less than 0.05%, the effect of improving the strength of the core material may be insufficient.

(23) Fe

(24) Fe improves the strength of the core material. The Fe content is preferably 0.7% or less. If the Fe content exceeds 0.7%, the self-corrosion rate may increase. If the Fe content is less than 0.05%, the effect of improving the strength of the core material may be insufficient.

(25) Ti

(26) Ti is separated into a high-concentration area and a low-concentration area in the thickness direction of the core material. These areas are distributed alternately in layers. Since the low-concentration area is preferentially corroded as compared with the high-concentration area, corrosion occurs in layers. This prevents the progress of corrosion in the thickness direction, and improves the corrosion resistance of the core material. The Ti content is preferably 0.01 to 0.3%. If the Ti content is less than 0.01%, a sufficient effect may not be obtained. If the Ti content exceeds 0.3%, a large crystallized product may be produced, and formability may deteriorate.

(27) Cu

(28) Cu increases the potential of the core material. Cu may be added to the core material in order to adjust the balance in potential with the inner cladding material. Cu included in the core material is diffused into the sacrificial anode material during brazing to reduce the potential difference between the core material and the sacrificial anode material, and increase the corrosion rate of the core material. Therefore, the Cu content is preferably 0.4% or less. If the difference between the Cu content in the core material and the Cu content in the inner cladding material is less than 0.2%, it may be difficult to provide a potential difference between the inner cladding material and the core material. Therefore, it is preferable that the Cu content in the core material be lower than the Cu content in the inner cladding material by 0.2% or more. The Cu content is more preferably less than 0.05%. Note that the advantageous effects of the invention are not impaired even if the core material includes 0.3% or less of V, 0.3% or less of Cr, 0.3% or less of Zr, and 0.3% or less of B.

(29) Inner Cladding Material

(30) Mn

(31) Mn improves the strength of the inner cladding material. The Mn content is preferably 0.6 to 2.0%. If the Mn content is less than 0.6%, a sufficient effect may not be obtained. If the Mn content exceeds 2.0%, it may be difficult to roll the material. The Mn content is more preferably 1.0 to 2.0%.

(32) Si

(33) Si improves the strength of the inner cladding material. The Si content is preferably 1.5% or less. If the Si content exceeds 1.5%, the melting point of the inner cladding material may decrease, and the inner cladding material may be easily melted during brazing. If the Si content is less than 0.05%, the effect of improving the strength of the inner cladding material may be insufficient.

(34) Fe

(35) Fe improves the strength of the inner cladding material. The Fe content is preferably 0.7% or less. If the Fe content exceeds 0.7%, the self-corrosion rate may increase. If the Fe content is less than 0.05%, the effect of improving the strength of the inner cladding material may be insufficient.

(36) Cu

(37) Cu increases the potential of the inner cladding material. Cu is added to the inner cladding material in order to adjust the balance in potential with the core material. The Cu content is preferably 0.2 to 1.5%. If the Cu content is less than 0.2%, a sufficient effect may not be obtained. If the Cu content exceeds 1.5%, the melting point of the inner cladding material may decrease, and the inner cladding material may easily melt during brazing. The Cu content is more preferably 0.2 to 0.8%.

(38) Ti

(39) Ti is separated into a high-concentration area and a low-concentration area in the thickness direction of the inner cladding material. These areas are distributed alternately in layers. Since the low-concentration area is preferentially corroded as compared with the high-concentration area, corrosion occurs in layers. This prevents the progress of corrosion in the thickness direction, and improves the corrosion resistance of the inner cladding material. The Ti content is preferably 0.01 to 0.3%. If the Ti content is less than 0.01%, a sufficient effect may not be obtained. If the Ti content exceeds 0.3%, a large crystallized product may be produced, and formability may deteriorate. Note that the advantageous effects of the invention are not impaired even if the inner cladding material includes 0.3% or less of V, 0.3% or less of Cr, 0.3% or less of Zr, and 0.3% or less of B.

(40) Note that it undesirable to limit the Si content and the Fe content in the sacrificial anode material, the core material, and the inner cladding material to less than 0.03% since the production cost increases when a high-purity ground metal is used.

(41) It is preferable to set the cladding ratio of the sacrificial anode material to 5 to 30%, and set the cladding ratio of the inner cladding material to 5 to 30%. If the cladding ratio of the sacrificial anode material is less than 5%, the Zn concentration in the sacrificial anode material may decrease due to diffusion during brazing, and a sufficient sacrificial anode effect may not be obtained. If the cladding ratio of the sacrificial anode material exceeds 30%, it may be difficult to implement clad rolling. The cladding ratio of the sacrificial anode material is more preferably 10 to 30%. If the cladding ratio of the inner cladding material is less than 5%, the Cu concentration in the inner cladding material may decrease due to diffusion during brazing, and the potential difference between the inner cladding material and the core material may decrease, whereby it may be difficult for the core material to exhibit a sacrificial anode effect. If the cladding ratio of the inner cladding material exceeds 30%, it may be difficult to implement clad rolling. The cladding ratio of the inner cladding material is more preferably 10 to 30%.

(42) A heat exchanger is produced by forming the aluminum alloy clad material into a tube so that the inner cladding material defines a refrigerant passage, and the sacrificial anode material comes in contact with the atmosphere, assembling an aluminum fin with the outer side (that comes in contact with the atmosphere) of the tube, or the outer side and the inner side (that defines the refrigerant passage) of the tube, and brazing the aluminum fin and the tube.

(43) As illustrated in FIG. 1, a tube material 1 may be produced by forming an aluminum alloy clad material 2 into a tube, inserting an inner fin 3 that is formed of a brazing sheet provided with a filler metal on each side, and brazing a joint 4 of the tube utilizing the filler metal provided to the inner fin 3. As illustrated in FIG. 2, the tube material 1 may also be produced by forming the aluminum alloy clad material 2 into a tube after applying a filler metal paste 5 to the sacrificial anode material of the aluminum alloy clad material 2 (or applying the filler metal paste 5 to the sacrificial anode material of the aluminum alloy clad material 2 after forming the aluminum alloy clad material 2 into a tube), and brazing the joint 4 utilizing the filler metal paste 5.

(44) When a heat exchanger is produced by forming the aluminum alloy clad material into a tube so that the inner cladding material defines a refrigerant passage, and the sacrificial anode material comes in contact with the atmosphere (defines the outer side), assembling an aluminum fin with the tube, and brazing the aluminum fin and the tube at 600 C. for 3 minutes, the potential of the sacrificial anode material, the potential of the core material, and the potential of the inner cladding material included in the tube have the relationship potential of sacrificial anode material<potential of core material<potential of the inner cladding material. Since the sacrificial anode material exhibits a sacrificial anode effect on the core material, and the core material exhibits a sacrificial anode effect on the inner cladding material, the sacrificial anode material and the core material function as a sacrificial anode layer with respect to the inner cladding material (i.e., the thickness of the sacrificial anode layer increases). Since the inner cladding material that has a higher potential remains even when most of the sacrificial anode material and the core material are consumed due to corrosion, it is possible to suppress the occurrence of a through-hole, and improve the corrosion resistance of the outer side (that comes in contact with the atmosphere).

EXAMPLES

(45) The invention is further described below by way of examples and comparative examples to demonstrate the advantageous effects of the invention. Note that the following examples are for illustration purposes only, and the invention is not limited to the following examples.

Example 1

(46) An ingot of a sacrificial anode material alloy (S1 to S11) having the composition shown in Table 1, and ingots of a core material alloy and an inner cladding material alloy (C1 to C19, C25 to C27) having the composition shown in Table 2, were cast using a semi-continuous casting method. The ingot of the sacrificial anode material alloy was homogenized at 500 C. for 8 hours, and hot-rolled (start temperature: 500 C.) to a given thickness. The ingot of the core material alloy was homogenized at 500 C. for 8 hours, and machined. The ingot of the inner cladding material alloy was homogenized at 500 C. for 8 hours, and hot-rolled (start temperature: 500 C.) to a given thickness.

(47) The hot-rolled material of the sacrificial anode material alloy and the hot-rolled material of the inner cladding material alloy were machined. The aluminum alloys were stacked in the combination shown in Table 3, hot-rolled (start temperature: 500 C.) to a thickness of 3 mm, cold-rolled, subjected to process annealing at 400 C., and then cold-rolled to obtain an aluminum alloy clad sheet material (specimens 1 to 28) having a thickness of 0.2 mm.

Comparative Example 1

(48) An ingot of a sacrificial anode material alloy (S12 to S16) having the composition shown in Table 1, and ingots of a core material alloy and an inner cladding material alloy (C20 to C24) having the composition shown in Table 2, were cast using a semi-continuous casting method. The ingot of the sacrificial anode material alloy (S1), and the ingots of the core material alloy and the inner cladding material alloy (C1, C9, C25) that were cast in Example 1 were also used in Comparative Example 1. The ingot of the sacrificial anode material alloy was homogenized at 500 C. for 8 hours, and hot-rolled (start temperature: 500 C.) to a given thickness. The ingot of the core material alloy was homogenized at 500 C. for 8 hours, and machined. The ingot of the inner cladding material alloy was homogenized at 500 C. for 8 hours, and hot-rolled (start temperature: 500 C.) to a given thickness. In Tables 1 and 2, the values that fall outside the scope of the invention are underlined.

(49) The hot-rolled material of the sacrificial anode material alloy and the hot-rolled material of the inner cladding material alloy were cut to given dimensions. The aluminum alloys were stacked in the combination shown in Table 4, hot-rolled (start temperature: 500 C.) to a thickness of 3 mm, cold-rolled, subjected to process annealing at 400 C., and then cold-rolled to obtain an aluminum alloy clad sheet material (specimens 101 to 112) having a thickness of 0.2 mm.

(50) The resulting specimen was heated at 600 C. for 3 minutes (equivalent to the brazing conditions), and subjected to potential measurement, a tensile test, and a corrosion test as described below. The results are shown in Tables 3 and 4.

(51) Potential Measurement

(52) The potential of the specimen was measured at room temperature in a 5% NaCl aqueous solution for which the pH was adjusted to 3 using acetic acid. The potential of the sacrificial anode material was measured in a state in which the area other than the surface of the sacrificial anode material was masked, and the potential of the inner cladding material was measured in a state in which the area other than the surface of the inner cladding material was masked. When measuring the potential of the core material, the specimen was ground from the sacrificial anode material so that the center of the core material was exposed, and the potential of the core material was measured in a state in which the area other than the exposed core material was masked.

(53) Tensile Test

(54) A JIS-5 specimen was prepared using the resulting specimen, and subjected to a tensile test in accordance with JIS Z 2241. A case where the tensile strength of the specimen was 95 MPa or more (equivalent to the strength of a 3003 alloy 0-material) was determined to be acceptable.

(55) Corrosion Test

(56) The specimen that was masked so that the sacrificial anode material was exposed, was subjected to a SWAAT test (ASTM G85) to evaluate corrosion resistance. A case where a through-hole was not observed when 1200 hours had elapsed, and the corrosion depth was less than 0.10 mm was evaluated as Very good, a case where a through-hole was not observed when 1200 hours had elapsed, and the corrosion depth was 0.10 mm or more was evaluated as Good, and a case where a through-hole occurred before 1200 hours elapsed was evaluated as Poor.

(57) TABLE-US-00001 TABLE 1 Component (mass %) No. Si Fe Mn Zn Other Al S1 0.1 0.3 0.0 2.5 Balance S2 0.1 0.2 0.0 0.6 Balance S3 0.1 0.3 0.0 1.2 Balance S4 0.1 0.2 0.0 6.5 Balance S5 0.1 0.2 0.0 9.7 Balance S6 0.4 0.1 0.0 2.0 Balance S7 0.2 0.5 0.0 2.0 Balance S8 0.1 0.1 0.5 2.5 Balance S9 1.2 0.0 0.2 3.8 Balance S10 0.2 0.2 0.0 2.0 Ti: 0.05, Cr: 0.05, V: 0.05, B: 0.05 Balance S11 0.2 0.2 1.4 1.5 Sn: 0.01, In: 0.01 Balance S12 2.0 0.1 0.2 3.0 Balance S13 0.4 1.0 0.4 4.5 Balance S14 0.4 0.3 2.0 5.0 Balance S15 0.5 0.4 0.5 0.1 Balance S16 0.3 0.2 0.2 11.6 Balance

(58) TABLE-US-00002 TABLE 2 Component (mass %) No. Si Fe Cu Mn Other Al C1 0.7 0.1 0.0 1.5 Balance C2 0.6 0.1 0.0 0.6 Balance C3 0.1 0.1 0.0 1.2 Balance C4 0.1 0.1 0.0 2.0 Balance C5 1.3 0.1 0.0 1.2 Balance C6 0.2 0.6 0.0 1.2 Balance C7 0.2 0.2 0.0 1.2 Ti: 0.2 Balance C8 0.7 0.2 0.0 1.2 Cr: 0.05, V: 0.05, B: 0.05 Balance C9 0.7 0.1 0.6 1.5 Balance C10 0.6 0.1 0.3 0.7 Balance C11 0.2 0.2 0.4 1.2 Balance C12 0.2 0.2 0.6 1.2 Balance C13 0.2 0.2 1.0 1.2 Balance C14 0.2 0.2 0.3 2.0 Balance C15 1.3 0.2 0.2 1.0 Balance C16 0.2 0.2 1.4 1.2 Balance C17 0.7 0.2 0.8 1.2 Balance C18 0.2 0.5 0.3 1.2 Ti: 0.2 Balance C19 0.4 0.2 0.6 1.2 Cr: 0.05, V: 0.05, B: 0.05 Balance C20 2.0 0.3 0.0 1.2 Balance C21 0.5 1.0 0.2 1.3 Balance C22 0.4 0.4 0.2 0.3 Balance C23 0.9 0.3 2.0 1.2 Balance C24 0.4 0.5 1.2 2.5 Balance C25 0.2 0.2 0.5 1.2 Balance C26 0.5 0.3 0.03 1.5 Balance C27 0.3 0.3 0.1 1.2 Balance

(59) TABLE-US-00003 TABLE 3 Specimen Sacrificial Inner SWAAT test anode material Core cladding material Potential (mV vs SCE) Tensile Corrosion Specimen Cladding ratio material Cladding ratio Sacrificial Core Inner cladding strength depth No. No. (%) No. No. (%) anode material material material (MPa) (mm) Evaluation 1 S1 10 C1 C9 20 800 690 650 140 <0.10 Very good 2 S1 20 C1 C9 10 850 690 650 130 <0.10 Very good 3 S1 20 C1 C9 20 850 690 650 135 <0.10 Very good 4 S2 20 C1 C9 20 730 690 650 135 <0.10 Very good 5 S3 20 C1 C9 20 770 690 650 135 <0.10 Very good 6 S4 20 C1 C9 20 915 690 650 135 <0.10 Very good 7 S5 20 C1 C9 20 930 690 650 135 <0.10 Very good 8 S6 20 C1 C9 20 830 690 650 135 <0.10 Very good 9 S7 20 C1 C9 20 830 690 650 140 <0.10 Very good 10 S8 20 C1 C9 20 840 690 650 140 <0.10 Very good 11 S9 20 C1 C9 20 860 690 650 140 <0.10 Very good 12 S10 20 C1 C9 20 840 690 650 135 <0.10 Very good 13 S11 20 C1 C9 20 900 690 650 140 <0.10 Very good 14 S1 20 C2 C10 20 850 700 670 100 <0.10 Very good 15 S1 20 C3 C11 20 850 700 670 110 <0.10 Very good 16 S1 20 C4 C12 20 850 700 650 115 <0.10 Very good 17 S1 20 C5 C13 20 850 690 640 135 <0.10 Very good 18 S1 20 C6 C14 20 850 700 670 130 <0.10 Very good 19 S1 20 C7 C15 20 850 700 670 130 <0.10 Very good 20 S1 20 C8 C16 20 850 690 610 135 <0.10 Very good 21 S1 20 C1 C17 20 850 690 645 135 <0.10 Very good 22 S1 20 C1 C18 20 850 690 670 135 <0.10 Very good 23 S1 20 C1 C19 20 850 690 670 135 <0.10 Very good 24 S1 20 C10 C9 20 850 670 650 145 0.12 Good 25 S1 20 C11 C9 20 850 670 650 145 0.13 Good 26 S1 20 C11 C25 20 850 670 655 145 0.16 Good 27 S1 20 C26 C9 20 850 690 650 135 <0.10 Very good 28 S1 20 C27 C9 20 850 685 650 140 0.10 Good

(60) TABLE-US-00004 TABLE 4 Specimen Sacrificial Inner SWAAT test anode material Core cladding material Potential (mV vs SCE) Tensile Corrosion Specimen Cladding ratio material Cladding ratio Sacrificial Core Inner cladding strength depth No. No. (%) No. No. (%) anode material material material (MPa) (mm) Evaluation 101 S12 20 C1 C9 20 840 690 650 135 Through-hole Poor occurred 102 S13 20 C1 C9 20 870 690 650 135 Through-hole Poor occurred 103 S14 20 C1 C9 20 880 690 650 135 Through-hole Poor occurred 104 S15 20 C1 C9 20 700 690 650 135 Through-hole Poor occurred 105 S16 20 C1 C9 20 940 690 650 135 Through-hole Poor occurred 106 S1 20 C20 C9 20 Core material melted 107 S1 20 C21 C9 20 850 680 650 145 Through-hole Poor occurred 108 S1 20 C22 C9 20 850 680 650 90 0.12 Good 109 S1 20 C1 C23 20 Inner cladding material melted 110 S1 20 C1 C24 20 Rolling cracks occurred 111 S1 10 C1 800 690 135 Through-hole Poor occurred 112 S1 20 C25 C9 20 850 660 650 145 Through-hole Poor occurred

(61) As shown in Table 3, specimens No. 1 to No. 28 according to the invention satisfied the relationship potential of sacrificial anode material<potential of core material<potential of the inner cladding material, and a through-hole did not occur during the SWAAT test. When a heat exchanger was produced by forming the aluminum alloy clad material into a tube so that the inner cladding material defines a refrigerant passage, and the sacrificial anode material comes in contact with the atmosphere (situated on the outer side), assembling an aluminum fin with the tube, and brazing the aluminum fin and the tube at 600 C. for 3 minutes, the outer side (that comes in contact with the atmosphere) of the tube exhibited an improved corrosion resistance.

(62) As shown in Table 4, the amount of self-corrosion of the sacrificial anode material increased, and a through-hole occurred during the SWAAT test when the Si content in the sacrificial anode material was too high (specimen No. 101), when the Fe content in the sacrificial anode material was too high (specimen No. 102), or when the Mn content in the sacrificial anode material was too high (specimen No. 103). Regarding specimen No. 104, the sacrificial anode effect of the sacrificial anode material was insufficient since the Zn content in the sacrificial anode material was too low, and a through-hole occurred during the SWAAT test. Regarding specimen No. 105, the amount of self-corrosion of the sacrificial anode material increased since the Zn content in the sacrificial anode material was too high, and a through-hole occurred during the SWAAT test.

(63) Regarding specimen No. 106, the core material melted during brazing since the Si content in the core material was too high. Regarding specimen No. 107, the amount of self-corrosion of the core material increased since the Fe content in the core material was high, and a through-hole occurred during the SWAAT test. Specimen No. 108 exhibited a low tensile strength since the Mn content in the core material was too low.

(64) Regarding specimen No. 109, the inner cladding material melted during brazing since the Cu content in the inner cladding material was too high. Regarding specimen No. 110, cracks occurred during cold rolling since the Mn content in the inner cladding material was too high, and a sound clad material could not be obtained. Specimen No. 111 corresponds to a known aluminum alloy clad material that consists only of the core material and the sacrificial anode material, and a through-hole occurred during the SWAAT test. Regarding specimen No. 112, the potential difference between the core material and the sacrificial anode material decreased since the Cu content in the core material was higher than 0.4%, and the potential difference between the core material and the inner cladding material was insufficient since the difference between the Cu content in the core material and the Cu content in the inner cladding material was less than 0.2%. As a result, a through-hole occurred during the SWAAT test.

REFERENCE SIGNS LIST

(65) 1 Tube material 2 Aluminum alloy clad material 3 Inner fin 4 Joint 5 Filler metal paste