Aluminum alloy clad material

Abstract

An aluminum alloy clad material includes: a sacrificial material on one surface of a core material; and an Al—Si—Mg—Bi-based brazing material disposed on other surface of the core material, contains, by mass %, Si: 6.0% to 14.0%, Mg: 0.05% to 1.5%, Bi: 0.05% to 0.25%, Sr: 0.0001% to 0.1%, and a balance consisting of Al and inevitable impurities, and satisfies a relationship of (Bi+Mg)×Sr≤0.1 by mass %, in which Mg—Bi-based compounds contained in the Al—Si—Mg—Bi-based brazing material with a diameter of 0.1 μm or more and less than 5.0 μm are more than 20 in number per 10,000-μm.sup.2 and the Mg—Bi-based compounds with a diameter of 5.0 μm or more are less than 2 in number, and the core material contains Mn: 0.9% to 1.7%, Si: 0.2% to 1.0%, Fe: 0.1% to 0.5%, Cu: 0.08% to 1.0%, and a balance consisting of Al and inevitable impurities.

Claims

1. An aluminum alloy clad material comprising three layers comprising: a sacrificial material disposed on one surface of a core material; and an Al—Si—Mg—Bi brazing material which is disposed on the other surface of the core material, comprising, by mass %, from 6.0% to 14.0% of Si, from 0.05% to 1.5% of Mg, from 0.05% to 0.25% of Bi, from 0.0001% to 0.1% of Sr, and a balance consisting of Al and inevitable impurities, and satisfying a relationship of (Bi+Mg)×Sr≤0.1 in amounts of elements by mass %, wherein the Al—Si—Mg—Bi brazing material comprises more than 20 in number per 10,000-μm.sup.2 visual field of Mg—Bi compounds having a diameter of from 0.1 μm to less than 5.0 μm, in terms of equivalent circle diameter and less than 2 in number per 10,000-μm.sup.2 visual field of the Mg—Bi compounds having a diameter of 5.0 μm or more, when observed in a surface layer plane direction before brazing, and wherein the core material comprises, by mass %, from 0.9% to 1.7% of Mn, from 0.2% to 1.0% of Si, from 0.1% to 0.5% of Fe, from 0.08% to 1.0% of Cu, and a balance consisting of Al and inevitable impurities.

2. The aluminum alloy clad material according to claim 1, wherein the core material further comprises from 0.1% to 0.7% of Mg and comprises a balance consisting of Al and inevitable impurities.

3. The aluminum alloy clad material according to claim 1, wherein the core material further comprises from 0.05% to 0.3% of Ti and comprises a balance consisting of Al and inevitable impurities.

4. The aluminum alloy clad material according to claim 2, wherein the core material further comprises from 0.05% to 0.3% of Ti and comprises a balance consisting of Al and inevitable impurities.

5. The aluminum alloy clad material according to claim 1, wherein a concentration of Mg on a surface of the brazing material at a braze melting temperature is from 0.15% to 1.0%.

6. The aluminum alloy clad material according to claim 2, wherein a concentration of Mg on a surface of the brazing material at a braze melting temperature is from 0.15% to 1.0%.

7. The aluminum alloy clad material according to claim 3, wherein a concentration of Mg on a surface of the brazing material at a braze melting temperature is from 0.15% to 1.0%.

8. The aluminum alloy clad material according to claim 4, wherein a concentration of Mg on a surface of the brazing material at a braze melting temperature is from 0.15% to 1.0%.

9. The aluminum alloy clad material according to claim 1, wherein the sacrificial material comprises, by mass %, at least one of from 0.2% to 6.0% of Zn, from 0.3% to 1.3% of Mn, from 0.2% to 0.8% of Si from 0.02% to 0.3% of Mg, from 0.2% to 0.8% of Fe, from 0.05% to 0.5% of Cr, and from 0.05% to 0.3% of Ti, and comprises a balance consisting of Al and inevitable impurities, and a concentration of Cu on a surface of the sacrificial material after brazing is 0.12% or less.

10. The aluminum alloy clad material according to claim 2, wherein the sacrificial material comprises, by mass %, at least one of from 0.2% to 6.0% of Zn, from 0.3% to 1.3% of Mn, from 0.2% to 0.8% of Si, from 0.02% to 0.3% of Mg, from 0.2% to 0.8% of Fe, from 0.05% to 0.5% of Cr, and from 0.05% to 0.3% of Ti, and comprises a balance consisting of Al and inevitable impurities, and a concentration of Cu on a surface of the sacrificial material after brazing is 0.12% or less.

11. The aluminum alloy clad material according to claim 3, wherein the sacrificial material comprises, by mass %, at least one of from 0.2% to 6.0% of Zn, from 0.3% to 1.3% of Mn, from 0.2% to 0.8% of Si, from 0.02% to 0.3% of Mg, from 0.2% to 0.8% of Fe, from 0.05% to 0.5% of Cr, and from 0.05% to 0.3% of Ti, and comprises a balance consisting of Al and inevitable impurities, and a concentration of Cu on a surface of the sacrificial material after brazing is 0.12% or less.

12. The aluminum alloy clad material according to claim 4, wherein the sacrificial material comprises, by mass %, at least one of from 0.2% to 6.0% of Zn, from 0.3% to 1.3% of Mn, from 0.2% to 0.8% of Si, from 0.02% to 0.3% of Mg, from 0.2% to 0.8% of Fe, from 0.05% to 0.5% of Cr, and from 0.05% to 0.3% of Ti, and comprises a balance consisting of Al and inevitable impurities, and a concentration of Cu on a surface of the sacrificial material after brazing is 0.12% or less.

13. The aluminum alloy clad material according to claim 5, wherein the sacrificial material comprises, by mass % at least one of from 0.2% to 6.0% of Zn, from 0.3% to 1.3% of Mn, from 0.2% to 0.8% of Si, from 0.02% to 0.3% of Mg, from 0.2% to 0.8% of Fe, from 0.05% to 0.5% of Cr, and from 0.05% to 0.3% of Ti, and comprises a balance consisting of Al and inevitable impurities, and a concentration of Cu on a surface of the sacrificial material after brazing is 0.12% or less.

14. The aluminum alloy clad material according to claim 6, wherein the sacrificial material comprises, by mass %, at least one from 0.2% to 6.0% of Zn, from 0.3% to 1.3% of Mn, from 0.2% to 0.8% of Si from 0.02% to 0.3% of Mg, from 0.2% to 0.8% of Fe, from 0.05% to 0.5% of Cr, and from 0.05% to 0.3% of Ti, and comprises a balance consisting of Al and inevitable impurities, and a concentration of Cu on a surface of the sacrificial material after brazing is 0.12% or less.

15. The aluminum alloy clad material according to claim 7, wherein the sacrificial material comprises, by mass %, at least one of from 0.2% to 6.0% of Zn, from 0.3% to 1.3% of Mn, from 0.2% to 0.8% of Si, from 0.02% to 0.3% of Mg, from 0.2% to 0.8% of Fe, from 0.05% to 0.5% of Cr and from 0.05% to 0.3% of Ti, and comprises a balance consisting of Al and inevitable impurities, and a concentration of Cu on a surface of the sacrificial material after brazing is 0.12% or less.

16. The aluminum alloy clad material according to claim 8, wherein the sacrificial material comprises, by mass %, at least one of from 0.2% to 6.0% of Zn, from 0.3% to 1.3% of Mn, from 0.2% to 0.8% of Si, from 0.02% to 0.3% of Mg, from 0.2% to 0.8% of Fe, from 0.05% to 0.5% of Cr, and from 0.05% to 0.3% of Ti, and comprises a balance consisting of Al and inevitable impurities, and a concentration of Cu on a surface of the sacrificial material after brazing is 0.12% or less.

17. The aluminum alloy clad material according to claim 1, wherein the Al—Si—Mg—Bi brazing material comprises, by mass %, from 0.1% to 1.5% of Mg.

18. The aluminum alloy clad material according to claim 1, wherein the Al—Si—Mg—Bi brazing material comprises, by mass %, from 0.2% to 1.5% of Mg.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a view illustrating a brazing sheet for flux-free brazing according to an embodiment of the present invention.

(2) FIG. 2 is a perspective view illustrating an aluminum heat exchanger for a vehicle according to the embodiment of the present invention.

(3) FIG. 3 is a view illustrating a brazing evaluation model in an example of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

(4) Hereinafter, an embodiment of the present invention will be described.

(5) An aluminum alloy clad material of the present embodiment in which a sacrificial material is disposed on one surface of a core material and a brazing material is disposed on the other surface can be manufactured, for example, by the following method.

(6) As an aluminum alloy for the core material, an aluminum alloy is adjusted to have a composition including, by mass %, Mn: 0.9% to 1.7%, Si: 0.2% to 1.0%, Fe: 0.1% to 0.5%, Cu: 0.08% to 1.0%, and Mg: 0.1% to 0.7%, further including one or two or more of Mg: 0.1% to 0.7% and Ti: 0.05% to 0.3%, and including a balance consisting of Al and inevitable impurities.

(7) As an aluminum alloy for the brazing material, an Al—Si-based brazing material having a composition including, by mass %, Si: 6.0% to 14.0%, Mg: 0.05% to 1.5%, Bi: 0.1% to 0.25%, Sr: 0.0001% to 0.1%, and a balance consisting of Al and inevitable impurities is used.

(8) In the present embodiment, in order to disperse a fine Mg—Bi compound at the time before brazing, Mg and Bi are dissolved in an ingot as a solid solution by performing casing at a high cooling rate from a high molten metal temperature during casting of the brazing material while suppressing coarse crystallization of the Mg—Bi compound.

(9) Specifically, the solid solubility of Mg and Bi can be increased by setting the molten metal temperature to 700° C. or higher.

(10) The obtained aluminum alloy ingot is subjected to a homogenization treatment under predetermined conditions. When the homogenization treatment temperature is low, a coarse Mg—Bi compound is precipitated and it is difficult to obtain the distributed state of the Mg—Bi compound of the present invention at the time before the brazing. Therefore, it is desirable to perform the treatment at a treatment temperature of 400° C. or higher for 1 to 10 hours.

(11) As an aluminum alloy for the sacrificial material, an aluminum alloy is adjusted to have a composition including, by mass %, one or two or more of Zn: 0.2% to 6.0%, Mn: 0.3% to 1.3%, Si: 0.2% to 0.8%, Mg: 0.02% to 0.3%, Fe: 0.2% to 0.8%, Cr: 0.05% to 0.5%, Ti: 0.05% to 0.3%, and including a balance consisting of Al and inevitable impurities. In the present invention, the composition of the sacrificial material is not limited thereto.

(12) Next, the brazing material is assembled with the core material and the sacrificial material and is subjected to hot clad rolling. At this time, in the present embodiment, the Mg—Bi compound is adjusted to a predetermined size and number density by controlling a rolling time at a predetermined temperature during hot rolling, an equivalent strain from the start to the end of the hot rolling, a hot rolling finish temperature, and a cooling rate after the hot rolling.

(13) First, by satisfying the rolling time in a predetermined temperature range during the hot rolling, precipitation of the Mg—Bi compound having a predetermined size defined in the present invention is promoted in an environment where dynamic strain is applied. Specifically, the precipitation of the fine Mg—Bi compound is promoted by setting the rolling time during which the material temperature during the hot rolling is between 400° C. and 500° C. to 10 minutes or more.

(14) Furthermore, by controlling the equivalent strain from the start to the end of the hot rolling, a coarse Mg—Bi crystallized product generated during the casting can be crushed and refined, and the number density thereof can be increased. Specifically, the Mg—Bi crystallized product is sufficiently refined by adjusting a slab thickness and a finish thickness so that the equivalent strain s represented by Formula (1) satisfies ε>5.0, thereby increasing the number density
ε=(2/√3)ln(t.sub.0/t)  Formula (1)

(15) t.sub.0: Hot rolling start thickness (slab thickness)

(16) t: Hot rolling finish thickness

(17) Furthermore, when the hot rolling finish temperature is high and a state without dynamic strain is maintained, or when the cooling rate after the hot rolling is slow, a coarser Mg—Bi compound than desired by the present invention is precipitated at grain boundaries and the like. Therefore, by securing a cooling rate of a certain level or more by reducing the hot rolling finish temperature to a predetermined temperature, the precipitation of a coarse Mg—Bi compound is suppressed.

(18) Specifically, the precipitation of a coarse Mg—Bi compound is suppressed by setting the hot rolling finish temperature to 250° C. to 350° C. and controlling the cooling rate from the finish temperature to 200° C. to be faster than −20° C./hr.

(19) Thereafter, through cold rolling or the like, an aluminum alloy clad material 1 of the present invention in which a brazing material 3 is disposed on one surface of a core material 2 and a sacrificial material 4 is disposed on the other surface of the core material 2 as illustrated in FIG. 1 is obtained.

(20) In the cold rolling, for example, cold rolling can be performed with a total reduction rate of 75% or more, process annealing can be performed at a temperature of 200° C. to 450° C., and then final rolling with a reduction rate of 40% can be performed. In cold rolling, the Mg—Bi compound is less likely to be crushed and does not deviate from the size and number density targeted by the present invention, so that the conditions are not particularly limited. Further, process annealing may not be performed, or H2n grade that has been finished by final annealing may be applied.

(21) The aluminum alloy clad material obtained in the above process is subjected to brazing as an assembly combined with other constituent members 10 (fin, tube, side plate, and the like illustrated in FIG. 1) as the constituent members of the heat exchanger.

(22) The assembly is disposed in a heating furnace having a non-oxidizing atmosphere under a normal pressure. A non-oxidizing gas can be constituted using an inert gas such as nitrogen gas, argon, a reducing gas such as hydrogen or ammonia, or a mixed gas thereof. Although the pressure of the atmosphere in a brazing furnace is basically the normal pressure, for example, in order to improve a gas replacement efficiency inside a product, a medium to low vacuum of about 100 kPa to 0.1 Pa in a temperature range before melting the brazing material may be employed, or a positive pressure of 5 to 100 Pa from the atmospheric pressure may be employed in order to suppress the infiltration of outside air (atmosphere) into the furnace.

(23) The heating furnace does not need to have a sealed space, and may be a tunnel type having a carry-in port and a carry-out port for the brazing material. Even in such a heating furnace, non-oxidizing properties are maintained by continuously blowing the inert gas into the furnace. The non-oxidizing atmosphere desirably has an oxygen concentration of 50 ppm or less by volume ratio.

(24) In the above atmosphere, for example, heating is performed at a temperature rising rate of 10 to 200° C./min, and braze joining is performed under heat treatment conditions in which an attainment temperature of the assembly is 559° C. to 630° C.

(25) Under the brazing conditions, the brazing time is shortened as the temperature rising rate is increased, so that the growth of an oxide film on a material surface is suppressed and the brazability is improved. Brazing is possible when the attainment temperature is equal to or higher than at least the solidus temperature of the brazing material. However, the brazing material which flows increases in amount as the temperature approaches the liquidus temperature, and a good joined state is easily obtained at a joint having an open portion. However, when the temperature is too high, brazing erosion tends to proceed, and the structural dimensional accuracy of the assembly after brazing decreases, which is not preferable.

(26) FIG. 2 illustrates an aluminum heat exchanger 5 in which fins 6 are formed using the aluminum alloy clad material 1 and a tube 7 made of an aluminum alloy is used as a brazing target material. The fin 6 and the tube 7 are assembled with a reinforcing member 8 and a header plate 9 to obtain the aluminum heat exchanger 5 for a vehicle or the like by flux-free brazing.

Example 1

(27) Various aluminum alloy clad materials having the compositions shown in Tables 1 to 3 and Tables 5 to 7 (balance consisting of Al and inevitable impurities) were produced into hot rolled sheets under the casting conditions, homogenization conditions (brazing material), and hot rolling conditions shown in Table 9. In addition, “-” in the component indicates that the content is 0 or the amount as an inevitable impurity.

(28) Thereafter, cold rolled sheets having a thickness of 0.30 mm and having an H14 equivalent grade were produced by cold rolling including process annealing. The clad ratio of each layer was 10% for the sacrificial material and 8% for the brazing material.

(29) Moreover, as the brazing target member, a corrugated fin of an aluminum bare material (0.06 mm thickness) of JIS A3003 alloy and H14 was prepared.

(30) A tube having a width of 25 mm was produced using the aluminum alloy clad material, and the tube and the corrugated fin were combined so that the tube brazing material and the corrugated fin are in contact with each other, thereby forming a core having a 15-stage tube and a length of 300 mm as a brazing evaluation model. The core was heated to 600° C. and held for 5 minutes in a brazing furnace in a nitrogen atmosphere (oxygen content 30 ppm), and the brazed state was evaluated. Here, a heat input amount from room temperature to 550° C. (the integral of the product of the diffusion coefficient of Zn and time during a brazing heat treatment) was set to 6×10.sup.−11 m.sup.2, a heat input amount until the completion of the brazing was set to 8×10.sup.−10 m.sup.2, and cooling to room temperature was performed after the end of the brazing at a cooling rate of 100° C./min. The brazing conditions are not limited to the above.

(31) For each specimen in the examples, the following evaluation was performed, and the evaluation results are shown in Tables 4 and 8.

(32) Brazability

(33) Joint Ratio

(34) A joint ratio was obtained by the following formula, and superiority and inferiority between samples were evaluated.
Fin joint ratio=(total brazing length of fin and tube/total contact length of fin and tube)×100

(35) Regarding the joint ratio, 90% or more was evaluated as O, and less than 90% was evaluated as X

(36) Fillet Length

(37) A sample cut out from the core was embedded in a resin and mirror-polished, and a fillet length W at a joint 13 between a fin 11 and a tube 12 was measured using an optical microscope as shown in FIG. 3. The number of joints 13 to be measured was 20 and the average thereof was taken as the fillet length to evaluate superiority or inferiority.

(38) In the fillet length, 800 m or more was evaluated as A, 700 m or more and less than 800 μm as B, 600 μm or more and less than 700 μm as C, 500 μm or more and less than 600 μm as D, and less than 500 m as E.

(39) Coarse Crystal Phase Si Particles

(40) A produced brazing sheet was embedded in a resin, a cross section thereof parallel to a rolling direction was mirror-polished, the structure thereof was revealed with Barker's solution and then observed with an optical microscope to evaluate the formation state of coarse primary state Si in a brazing material layer. Observation was performed on a visual field of 300 μm at 10 points.

(41) A case where coarse Si particles having an equivalent circle diameter of 30 μm or more were less than 2 in number was evaluated as A, a range from 2 to 9 was evaluated as B, and a case of 10 or more particles was evaluated as C.

(42) Strength after Brazing

(43) The brazing sheet was placed in a furnace in a drop form, and a brazing equivalent heat treatment was performed under the brazing conditions. Thereafter, the sample was cut out, a tensile test was conducted at room temperature by a normal method based on JIS, and a tensile strength was evaluated.

(44) Regarding the strength after brazing, 190 MPa or more was evaluated as A, 180 MPa or more and less than 190 MPa as B, 145 MPa or more and less than 180 MPa as C, and less than 145 MPa as D.

(45) Corrosion Resistance

(46) The brazing sheet was placed in the furnace in a drop form, and the brazing equivalent heat treatment was performed under the brazing conditions. Thereafter, the sample was cut into a size of 30 mm×80 mm, masked except for a sacrificial material surface, and then subjected to SWAAT for 30 days. Corrosion products were removed from the sample after the corrosion test with chromic acid phosphate, and the corrosion depth was measured by observing the cross section of a maximum corrosion portion.

(47) Regarding the corrosion resistance, a case where the corrosion depth was in the sacrificial material layer was evaluated as A, exceeding the sacrificial material layer to ¼ of the sheet thickness as B, exceeding the sacrificial material layer to half the sheet thickness as C, not penetrated although exceeding half the sheet thickness as D. Among the test materials that were penetrated in SWAAT for 30 days, a case where there was no penetration in 20 days but penetration occurred after 20 days was evaluated as E, and a case where penetration occurred in 20 days was evaluated as F.

(48) Mg Concentration of Surface of Brazing Material at Braze Melting Temperature

(49) The brazing equivalent heat treatment was performed under the above brazing conditions, the sample was taken out from the furnace at the moment when the braze melting temperature (a solidus temperature was calculated from the components using the phase diagram calculation software JMatPro, and a temperature subtracted by 10° C. from the solidus temperature) was reached, the sample was embedded in a resin and mirror-polished, and the Mg concentration on the surface of the brazing material was measured by EPMA analysis in a cross-sectional direction. In the measured EPMA data, the average Mg concentration in a range of 5 μm from the surface of the brazing material was taken as the Mg concentration on the surface of the brazing material.

(50) Since the braze melting temperature varies depending on the components of a material, the solidus temperature was obtained using the phase diagram calculation software (JMatPro), and the temperature subtracted by 10° C. from the solidus temperature was treated as the braze melting temperature.

(51) Cu Concentration on Surface of Sacrificial Material after Brazing

(52) The brazing equivalent heat treatment was performed under the brazing conditions, the sample after the brazing was embedded in a resin and mirror-polished, and the Cu concentration on the surface of the sacrificial material was measured by EPMA analysis in a cross-sectional direction. In the measured EPMA data, the average Cu concentration in a range of 5 μm from the surface was taken as the Cu concentration on the surface of the sacrificial material.

(53) TABLE-US-00001 TABLE 1 Elements added to brazing material Mg—Bi compound [wt %] Manufacturing [/10,000 μm.sup.2] Specimen No. Mg Si Bi Sr method Less than 5 μm 5 μm or more (Bi + Mg) × Sr Example 1 0.05 11.0 0.15 0.0005 E 24 0 0.0001 2 0.1 11.0 0.15 0.0005 E 39 0 0.000125 3 0.2 11.0 0.15 0.0005 E 41 0 0.000175 4 0.6 11.0 0.15 0.0005 F 35 0 0.000375 5 0.9 11.0 0.23 0.007 H 44 0 0.00791 6 0.9 11.0 0.23 0.007 H 44 0 0.00791 7 1.2 11.0 0.23 0.007 H 44 0 0.01001 8 1.4 11.0 0.23 0.007 H 44 0 0.01141 9 0.5 6.0 0.23 0.008 I 54 0 0.00584 10 0.3 9.0 0.20 0.007 B 34 0 0.0035 11 0.3 13.0 0.10 0.005 E 38 0 0.002 12 0.5 14.0 0.20 0.005 G 55 1 0.0035 13 0.3 11.5 0.05 0.005 I 32 0 0.00175 14 0.5 11.5 0.08 0.008 F 33 0 0.00464 15 0.5 11.5 0.23 0.006 A 40 0 0.00438 16 0.5 11.5 0.25 0.006 B 46 0 0.0045 17 0.5 12.5 0.15 0.0001 E 38 0 0.000065 18 0.5 12.5 0.15 0.0005 F 31 0 0.000325 19 0.2 12.5 0.15 0.05 I 33 0 0.0175 20 0.05 12.5 0.15 0.1 E 22 0 0.02 21 0.1 12.5 0.15 0.1 E 35 0 0.025 22 0.5 11.5 0.15 0.008 E 37 0 0.0052 23 0.5 11.5 0.20 0.006 A 38 0 0.0042 24 0.5 11.5 0.20 0.007 D 43 0 0.0049 25 0.5 11.5 0.20 0.008 B 33 0 0.0056 26 0.5 11.5 0.20 0.01 F 47 0 0.007 27 1.2 11.5 0.20 0.01 B 33 0 0.014 28 1.2 11.5 0.20 0.009 J 66 1 0.0126 29 1.0 11.5 0.20 0.01 A 41 0 0.012 30 1.0 11.5 0.20 0.08 B 36 0 0.096 31 0.3 11.5 0.20 0.004 I 55 0 0.002 32 0.3 11.5 0.15 0.007 E 41 0 0.00315 33 0.3 11.5 0.15 0.005 G 33 0 0.00225 34 0.3 11.5 0.15 0.01 J 47 0 0.0045 35 0.8 11.5 0.15 0.01 I 35 0 0.0095 36 0.8 11.5 0.20 0.08 C 38 0 0.08 37 0.5 11.5 0.20 0.008 D 44 0 0.0056 38 0.5 11.5 0.15 0.01 I 38 0 0.0065 39 0.5 11.5 0.15 0.009 J 42 0 0.00585 40 0.5 11.5 0.20 0.01 H 43 0 0.007 41 0.5 11.5 0.20 0.006 A 41 0 0.0042 42 0.5 11.5 0.20 0.0002 J 66 1 0.00014 43 0.5 11.5 0.23 0.01 B 47 0 0.0073 44 0.5 11.5 0.12 0.01 F 33 0 0.0062 45 0.5 11.5 0.20 0.008 B 34 0 0.0056 46 0.5 11.5 0.15 0.01 G 36 0 0.0065 47 0.3 10.0 0.20 0.009 B 34 0 0.0045 48 0.3 10.0 0.20 0.009 B 34 0 0.0045 49 0.3 10.0 0.20 0.009 B 34 0 0.0045 50 0.3 10.0 0.20 0.009 B 34 0 0.0045 51 0.3 10.0 0.20 0.01 B 34 0 0.005 52 0.3 10.0 0.20 0.005 B 34 0 0.0025 53 0.3 10.0 0.20 0.01 B 34 0 0.005 54 0.3 10.0 0.20 0.01 B 34 0 0.005 55 0.3 10.0 0.20 0.007 B 34 0 0.0035 56 0.3 10.0 0.20 0.01 B 34 0 0.005 57 0.3 10.0 0.20 0.006 B 34 0 0.003 58 0.3 10.0 0.20 0.004 B 34 0 0.002 59 0.3 7.5 0.20 0.002 B 34 0 0.001 60 0.8 11.0 0.20 0.08 E 35 0 0.08 61 0.5 11.5 0.20 0.01 C 38 0 0.007 62 0.5 11.5 0.15 0.008 E 37 0 0.0052 63 0.5 11.5 0.2 0.01 C 38 0 0.007 64 0.5 11.5 0.15 0.01 G 33 0 0.0065 65 0.5 11.5 0.20 0.007 H 44 0 0.0049 66 0.3 11.5 0.20 0.01 A 42 0 0.005 67 0.5 11.5 0.2 0.01 C 38 0 0.007

(54) TABLE-US-00002 TABLE 2 Concentration of Mg Core material composition [wt %] on surface of brazing Specimen No. Si Mg Mn Cu Ti Fe material (wt %) Example 1 0.7 0.5 1.2 0.4 — 0.2 0.07 2 0.7 0.5 1.2 0.4 — 0.2 0.15 3 0.7 0.5 1.2 0.4 — 0.2 0.21 4 0.7 0.5 1.2 0.4 — 0.2 0.59 5 0.7 0.1 1.2 0.4 0.15 0.2 0.85 6 0.7 0.5 1.2 0.4 0.15 0.2 0.9 7 0.7 — 1.2 0.4 0.15 0.2 1.1 8 0.7 0.5 1.2 0.4 0.15 0.2 1.32 9 0.7 0.5 1.2 0.4 0.15 0.2 0.5 10 0.7 0.5 1.2 0.4 0.15 0.2 0.31 11 0.7 0.5 1.2 0.4 0.15 0.2 0.31 12 0.7 0.5 1.2 0.4 0.1 0.2 0.5 13 0.7 0.5 1.2 0.4 0.1 0.2 0.31 14 0.7 0.5 1.2 0.4 0.1 0.2 0.5 15 0.7 0.5 1.2 0.4 0.1 0.2 0.5 16 0.7 0.5 1.2 0.4 0.1 0.2 0.5 17 0.7 0.5 1.2 0.4 — 0.2 0.5 18 0.7 — 1.2 0.4 — 0.2 0.47 19 0.7 — 1.2 0.4 — 0.2 0.20 20 0.7 — 1.2 0.4 — 0.2 0.03 21 0.7 — 1.2 0.4 — 0.2 0.08 22 0.5 — 1.2 0.4 — 0.2 0.45 23 0.6 — 1.2 0.4 — 0.2 0.46 24 0.9 — 1.2 0.4 — 0.2 0.44 25 1.0 — 1.2 0.4 — 0.2 0.47 26 0.75 0.1 1.2 0.6 — 0.2 0.49 27 0.75 0.2 1.2 0.6 — 0.2 1.05 28 0.75  0.65 1.2 0.6 — 0.2 1.15 29 0.75 0.7 1.2 0.6 — 0.2 0.95 30 0.7 0.5 1.1 0.55 — 0.2 0.95 31 0.7 0.5 1.2 0.55 — 0.2 0.307 32 0.7 0.5 1.6 0.55 — 0.2 0.307 33 0.7 0.5 1.7 0.55 — 0.2 0.307 34 0.85 0.5 1.2 0.1 — 0.2 0.307 35 0.85 0.5 1.2 0.15 — 0.2 0.78 36 0.85 0.5 1.2 0.6 — 0.2 0.75 37 0.5 0.5 1.2 0.4 — 0.10 0.5 38 0.5 0.5 1.2 0.4 — 0.12 0.5 39 0.5 0.5 1.2 0.4 — 0.4 0.5 40 0.5 — 1.2 0.4 — 0.5 0.47 41 0.7 — 1.2 0.4 — 0.2 0.46 42 0.7 — 1.2 0.4 — 0.2 0.45 43 0.7 — 1.2 0.4 — 0.2 0.45 44 0.7 — 1.2 0.4 — 0.2 0.45 45 0.7 — 1.2 0.4 — 0.2 0.44 46 0.7 — 1.2 0.4 — 0.2 0.43 47 0.7 — 1.2 0.4 — 0.2 0.29 48 0.7 — 1.2 0.4 — 0.2 0.28 49 0.7 — 1.2 0.4 — 0.2 0.29 50 0.7 — 1.2 0.4 — 0.2 0.27 51 0.7 — 1.2 0.4 0.2 0.2 0.28 52 0.7 0.5 1.2 0.4 0.2 0.2 0.31 53 0.7 0.5 1.2 0.4 0.2 0.2 0.31 54 0.7 0.5 1.2 0.4 0.2 0.2 0.31 55 0.7 0.5 1.2 0.4 0.08 0.2 0.31 56 0.7 0.5 1.2 0.4 0.08 0.2 0.31 57 0.7 0.5 1.2 0.4 0.08 0.2 0.31 58 0.7 0.5 1.2 0.4 0.08 0.2 0.31 59 0.7 0.5 1.2 0.4 — 0.2 0.31 60 0.7 0.2 1.4 0.4 — 0.2 0.75 61 0.85 — 1.2 0.7 — 0.2 0.45 62 0.2 — 1.2 0.4 — 0.2 0.45 63 0.85 — 1.2 1.0 — 0.2 0.45 64 0.4 — 1.2 0.2 — 0.2 0.47 65 0.7 — 1.2 0.08 0.15 0.2 0.47 66 0.1 — 1.4 0.9 0.15 0.2 0.28 67 0.85 — 1.2 0.85 — 0.2 0.45

(55) TABLE-US-00003 TABLE 3 Sacrificial material composition [wt %] Specimen No. Zn Mn Si Fe Cr Ti Mg Example 1 3.0 — — 0.3 — — — 2 3.0 — — 0.3 — — — 3 3.0 — — 0.3 — — 0.01 4 3.0 — — 0.3 — — 0.2  5 3.0 — — 0.3 — — 0.07 6 3.0 — — 0.3 — — 0.07 7 3.0 — — 0.3 — — 0.07 8 3.0 — — 0.3 — — 0.07 9 3.0 — — 0.3 — — — 10 3.0 — — 0.3 — — — 11 3.0 — — 0.3 — — — 12 3.0 — — 0.5 — — 0.03 13 3.0 — — 0.5 — — — 14 3.0 — 0.5 — — — — 15 3.0 — 0.5 — — — — 16 3.0 — 0.5 — — — 0.06 17 3.0 — 0.5 0.3 — — — 18 3.0 — 0.5 0.3 — — — 19 3.0 0.8 — 0.3 — — — 20 3.0 0.8 — 0.3 — — — 21 3.0 0.8 — 0.3 — — — 22 3.0 0.8 — 0.5 — — — 23 3.0 0.8 — 0.5 — 0.1 — 24 3.0 0.8 — 0.5 — 0.1 — 25 3.0 0.8 — 0.5 — 0.1 0.05 26 3.0 0.5 — — —  0.05 — 27 3.0 0.5 — — — 0.3 — 28 3.0 0.5 — — — — — 29 3.0 0.5 — — — — — 30 3.0 0.5 — — — — — 31 3.0 0.5 — —  0.05 — — 32 3.0 — — — 0.5 — — 33 3.0 — — — 0.2 — 0.25 34 — — — — 0.2 — — 35 — — — — 0.2 — — 36 — — — — 0.2 — — 37 3.0 0.8 — — 0.2 — — 38 3.0 0.8 0.5 — — — — 39 3.0 0.8 0.5 — — — — 40 3.0 0.8 0.5 — — — — 41 0.2 0.5 — 0.3 0.1 — — 42 6.0 0.5 — 0.3 0.1 — — 43 3.0 0.3 — 0.3 — — — 44 3.0 1.3 — 0.3 — — — 45 3.0 0.5 0.2 0.3 — — — 46 3.0 — 0.8 0.3 — — — 47 — — — — — — — 48 0.2 — — — — — — 49 0.5 — — — — — — 50  0.65 — — — — — — 51 2.0 — — — — — — 52 3.0 — — — — — — 53 2.0 0.5 — — — — — 54 2.0 — 0.5 — — — — 55 2.0 — — — 0.2 — — 56 — — — — — — 0.04 57 — — — — — — 0.1  58 — — — — — — 0.22 59 — — — — — — 0.29 60 3.0 — — — — — — 61 — — — — 0.2 — — 61 — — — — 0.2 — — 62 3.0 0.8 — 0.5 — — — 63 — — — — 0.2 — — 64 3.0 0.8 — 0.5 — — — 65 — — — — 0.2 — — 66 — — — — 0.2 — — 67 — — — — 0.2 — —

(56) TABLE-US-00004 TABLE 4 Corrosion resistance Concentration Brazability of Cu on surface Coarse of sacrificial Joint Fillet Si material Cu Corrosion Strength after brazing Specimen No. ratio length particles [wt %] depth [MPa] Evaluation Example 1 O D A 0.07 A 182 B 2 O C A 0.07 A 182 B 3 O B A 0.07 A 183 B 4 O A A 0.07 A 185 B 5 O A A 0.07 A 168 C 6 O B A 0.07 A 186 C 7 O C A 0.07 A 165 C 8 O D A 0.07 A 189 C 9 O D A 0.07 A 184 B 10 O B A 0.07 A 183 B 11 O B A 0.07 A 183 B 12 O D A 0.07 A 184 B 13 O C A 0.07 A 183 B 14 O B A 0.07 A 186 B 15 O B A 0.07 A 186 B 16 O C A 0.07 A 186 B 17 O B A 0.07 A 186 B 18 O B A 0.07 A 164 C 19 O B A 0.07 A 162 C 20 O D A 0.07 A 162 C 21 O D A 0.07 A 162 C 22 O B A 0.07 A 157 C 23 O B A 0.07 A 160 C 24 O B A 0.07 A 172 C 25 O C A 0.07 A 176 C 26 O A A 0.10 A 176 C 27 O D A 0.09 A 184 B 28 O A A 0.10 A 205 A 29 O B A 0.10 A 206 A 30 O C B 0.07 A 192 A 31 O A A 0.07 A 190 A 32 O B A 0.07 A 194 A 33 O B A 0.07 A 196 A 34 O A A 0.02 B 177 C 35 O B A 0.03 B 181 B 36 O B B 0.11 D 198 A 37 O B A 0.07 A 178 C 38 O B A 0.07 A 180 B 39 O B A 0.07 A 182 B 40 O A A 0.07 A 160 C 41 O B A 0.07 A 163 C 42 O A A 0.07 A 163 C 43 O A A 0.07 A 162 C 44 O B A 0.07 A 165 C 45 O B A 0.07 A 164 C 46 O B A 0.07 A 165 C 47 O B A 0.07 D 160 C 48 O B A 0.07 C 160 C 49 O B A 0.07 B 160 C 50 O B A 0.07 A 160 C 51 O B A 0.07 B 160 C 52 O B A 0.07 B 183 B 53 O B A 0.07 A 184 B 54 O B A 0.07 A 185 B 55 O B A 0.07 A 183 B 56 O B A 0.07 B 183 B 57 O B A 0.07 B 183 B 58 O B A 0.07 A 183 B 59 O C A 0.07 A 183 B 60 O B B 0.07 A 172 C 61 O B A 0.13 C 178 C 62 O B A 0.07 A 150 C 63 O B A 0.18 E 188 B 64 O C A 0.07 A 146 C 65 O C A 0.015 A 149 C 66 O C A 0.14 E 159 C 67 O C A 0.15 D 183 B

(57) TABLE-US-00005 TABLE 5 Elements added to brazing material Mg—Bi compound [wt %] Manufacturing [/10,000 μm.sup.2] Specimen No. Mg Si Bi Sr method Less than 5 μm 5 μm or more (Bi + Mg) × Sr Comparative 1 0.02 11.0 0.11 0.0005 B 17 0 0.000065 Example 2 1.55 11.0 0.15 0.0005 E 32 0 0.00085 3 0.5 5.5 0.23 0.01 A 42 0 0.0073 4 1.3 14.5 0.20 0.08 I 55 1 0.12 5 0.1 11.5 0.03 0.0005 C 24 0 0.000065 6 0.5 11.5 0.28 0.01 C 45 1 0.0078 7 0.5 12.5 0.15 0.00008 C 42 0 0.000052 8 0.5 12.5 0.20 0.15 C 42 0 0.105 9 0.5 11.5 0.15 0.005 I 36 0 0.00325 10 0.5 11.5 0.15 0.01 J 46 1 0.0065 11 0.5 11.5 0.20 0.006 C 35 0 0.0042 12 0.3 11.5 0.20 0.005 D 45 0 0.0025 13 0.3 11.5 0.20 0.01 B 35 0 0.005 14 1.2 11.5 0.20 0.08 B 36 0 0.112 15 1.2 11.5 0.15 0.04 B 34 0 0.054 16 0.3 11.5 0.15 0.01 K 12 3 0.0045 17 0.3 11.5 0.15 0.007 N 19 5 0.00315 18 0.5 11.5 0.20 0.007 O 16 4 0.0049 19 0.5 11.5 0.20 0.01 L 19 7 0.007 20 0.5 11.5 0.15 0.008 M 15 6 0.0052 21 0.5 11.5 0.15 0.01 K 13 5 0.0065 22 1.0 11.5 0.12 0.006 N 18 3 0.00672 23 0.5 11.5 0.28 0.01 C 45 1 0.0078 24 0.5 11.5 0.20 0.007 H 44 0 0.0049 25 0.5 11.5 0.15 0.01 G 33 0 0.0065 26 0.3 11.5 0.20 0.01 A 42 0 0.005 Reference 1 0.5 11.5 0.15 0.0007 Cannot be evaluated 0.000455 Example 2 0.5 11.5 0.15 0.01 Cannot be evaluated 0.0065 3 0.5 11.5 0.15 0.008 Cannot be evaluated 0.0052 4 0.5 11.5 0.15 0.009 Cannot be evaluated 0.00585 5 0.5 11.5 0.15 0.01 Cannot be evaluated 0.0065 6 0.3 10.0 0.20 0.01 Cannot be evaluated 0.005

(58) TABLE-US-00006 TABLE 6 Concentration of Mg Core material composition [wt %] on surface of brazing Specimen No. Si Mg Mn Cu Ti Fe material (wt %) Comparative 1 0.7 0.5 1.2 0.4 — 0.2 0.094 Example 2 0.7 0.5 1.2 0.4 — 0.2 1.5 3 0.7 0.5 1.2 0.4 — 0.2 0.5 4 0.7 0.5 1.2 0.4 — 0.2 1.2 5 0.7 0.5 1.2 0.4 — 0.2 0.21 6 0.5 — 0.9 0.4 — 0.2 0.48 7 0.7 — 1.2 0.4 — 0.2 0.45 8 0.7 — 1.2 0.4 — 0.2 0.47 9 1.2 0.5 1.2 0.2 — 0.2 0.5 10 0.7 0.2 1.2 0.4 — 0.2 0.49 11 0.7 0.2 1.8 0.4 — 0.2 0.49 12 0.5 0.3 1.2 0.4  0.15 0.08 0.3 13 0.5 0.3 1.2 0.4  0.15 0.7 0.3 14 0.7 0.5 1.8 0.4 0.2 0.2 1.1 15 0.7 0.5 1.2 0.4 0.5 0.2 1.1 16 0.7 0.5 1.2 0.4 — 0.2 0.307 17 0.7 0.5 1.2 0.4 — 0.2 0.307 18 0.7 0.5 1.2 0.4 — 0.2 0.5 19 0.7 0.5 1.2 0.4 — 0.2 0.5 20 0.7 0.5 1.2 0.4 — 0.2 0.5 21 0.7 0.5 1.2 0.4 — 0.2 0.5 22 0.7 0.5 1.2 0.4 — 0.2 0.5 23 0.5 — 0.7 0.4 — 0.2 0.48 24 0.7 — 1.2 0.04  0.15 0.2 0.47 25 0.15 — 1.2 0.2 — 0.2 0.47 26 0.1 — 1.4 1.1  0.15 0.2 0.28 Reference 1 0.7 0.5 1.2 0.4 0.5 0.4 Example 2 0.7 0.5 1.2 0.4 0.5 0.2 3 0.7 1.5 1.2 0.4 0.3 0.2 4 0.7 0.5 1.7 0.4 0.3 0.2 5 0.7 0.5 1.7 0.4 — 0.4 6 0.7 1.5 1.6 0.4 — 0.4

(59) TABLE-US-00007 TABLE 7 Sacrificial material composition [wt %] Specimen No. Zn Mn Si Fe Cr Ti Mg Comparative 1 3.0 — — 0.3 — — 0.1  Example 2 3.0 — — 0.3 — — — 3 3.0 — — 0.3 — — 0.05 4 3.0 — — 0.3 — — — 5 3.0 — — 0.5 — — — 6 3.0 — 0.5 — — — 0.08 7 3.0 — 0.5 0.3 — — — 8 3.0 — 0.5 0.3 — — — 9 3.0 0.8 — 0.5 — 0.1 — 10 3.0 0.5 — — — 0.1 0.02 11 3.0 0.5 — — 0.1 — — 12 3.0 0.8 — — 0.2 — — 13 3.0 0.8 0.5 — — — — 14 0.2 0.5 — 0.3 0.1 — — 15 6.0 0.5 — 0.3 0.1 — 0.03 16 3.0 1.0 — 0.3 — — — 17 3.0 0.5 0.2 0.3 — — — 18 3.0 — — 0.3 — — — 19 3.0 0.5 — 0.3 — — — 20 3.0 — 0.4 0.3 — — — 21 3.0 0.5 0.3 0.3 — — — 22 3.0 — 0.4 0.3 — — — 23 3.0 — 0.5 — — — 0.08 24 — — — — 0.2 — — 25 3.0 0.8 — 0.5 — — — 26 — — — — 0.2 — — Reference 1 3.0 1.8 0.4 0.4 — — 0.02 Example 2 3.0 — 0.4 1.0 0.1 — 0.09 3 3.0 0.5 0.4 0.3 0.6 0.1 0.2  4 3.0 — 0.4 0.5 — 0.4 — 5 3.0 — 0.4 0.5 — 0.1 — 6 — — — — — — 0.4 

(60) TABLE-US-00008 TABLE 8 Corrosion resistance Brazability Surface of Coarse sacrificial Joint Fillet Si material Cu Corrosion Strength after brazing Specimen No. ratio length particles [wt %] depth [MPa] Evaluation Comparative 1 X E A 0.07 A 182 B Example 2 X E A 0.07 A 189 B 3 O E A 0.07 A 184 B 4 X E C 0.07 A 188 B 5 O E A 0.07 A 182 B 6 X E A 0.07 A 149 C 7 X E C 0.07 A 165 C 8 Evaluation material cannot be manufactured and evaluated. 9 Poor brazing due to generation 0.07 A 190 A of significant erosion 10 O C A 0.07 A 172 C 11 Evaluation material cannot be manufactured and evaluated. 12 O A A 0.07 A 168 C 13 Evaluation material cannot be manufactured and evaluated. 14 Evaluation material cannot be manufactured and evaluated. 15 Evaluation material cannot be manufactured and evaluated. 16 O E A 0.07 A 186 B 17 O E A 0.07 A 185 B 18 O E A 0.07 A 184 B 19 O E A 0.07 A 186 B 20 O E A 0.07 A 186 B 21 O E A 0.07 A 187 B 22 O E A 0.07 A 188 B 23 X E A 0.07 A 143 D 24 O C A 0.013 A 144 D 25 O C A 0.07 A 135 D 26 O C A 0.20 F 170 C Reference 1 Evaluation material cannot be manufactured and evaluated. Example 2 Evaluation material cannot be manufactured and evaluated. 3 Evaluation material cannot be manufactured and evaluated. 4 Evaluation material cannot be manufactured and evaluated. 5 Evaluation material cannot be manufactured and evaluated. 6 Evaluation material cannot be manufactured and evaluated.

(61) TABLE-US-00009 TABLE 9 (Brazing material) Casting Hot rolling condition condition Homogenization Rolling time Molten condition between metal Temperature 400° C. and Equivalent Finish Cooling Specimen temperature and time 500° C. strain temperature rate No. (° C.) (° C., h) (min) ε (° C.) (° C./h) Target A 710 450° C., 5 h 15 5.7 320 25 range B 715 450° C., 5 h 14 5.4 334 21 C 715 500° C., 2 h 10 5.5 355 35 D 725 550° C., 2 h 14 5.5 274 28 E 725 400° C., 8 h 18 5.9 290 38 F 735 400° C., 8 h 22 5.7 252 35 G 735 450° C., 8 h 15 6.1 315 42 H 720 450° C., 8 h 24 5 340 34 I 755 500° C., 5 h 14 6.4 347 52 J 745 500° C., 5 h 30 5 290 32 Outside K 695 400° C., 8 h 15 5.3 267 18 the target L 680 380° C., 8 h 8 5.2 220 12 M 715 380° C., 8 h 22 4.8 337 36 N 670 350° C., 8 h 15 4.6 395 22 O 705 350° C., 8 h 7 5.7 322 35

(62) While preferred embodiments of the invention have been described and illustrated above, it should be understood that these are exemplary of the invention and are not to be considered as limiting. Additions, omissions, substitutions, and other modifications can be made without departing from the spirit or scope of the present invention. Accordingly, the invention is not to be considered as being limited by the foregoing description, and is only limited by the scope of the appended claims.