ALUMINUM ALLOY CLAD MATERIAL

Abstract

A sacrificial material on one surface of a core material, a Al brazing material containing 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 Al balance and satisfying (Bi+Mg)Sr0.1 is disposed on the other surface, Mg-Bi-based compounds of the brazing material with a diameter of 0.1-5.0 m are more than 20 per 10,000-m.sup.2 and the Mg-Bi-based compounds with a diameter of 5.0 m or more are less than 2 before brazing, the core material contains Mn: 1.0% to 1.7%, Si: 0.2% to 1.0%, Fe: 0.1% to 0.5%, Cu: 0.08% to 1.0%, Mg: 0.1% to 0.7%, and Al balance, the sacrificial material contains Zn: 0.5% to 6.0% and Mg of which a content is limited to 0.1% or less, and a Mg concentration on a surface of the sacrificial material after brazing is 0.15% or less.

Claims

1. An aluminum alloy clad material comprising: a sacrificial material disposed on one surface of a core material; and an AlSiMgBi brazing material which is disposed on the 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)Sr0.1 in amounts of elements by mass %, wherein MgBi compounds contained in the AlSiMgBi brazing material and having a diameter of 0.1 m or more and less than 5.0 m in terms of equivalent circle diameter are more than 20 in number per 10,000-m.sup.2 visual field and the MgBi compounds having a diameter of 5.0 m or more are less than 2 in number per 10,000-m.sup.2 visual field when observed in a surface layer plane direction before brazing, the core material contains, by mass %, Mn: 1.0% 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, and the sacrificial material contains, by mass %, Zn: 0.5% to 6.0% and Mg of which a content is limited to 0.1% or less, and a Mg concentration on a surface of the sacrificial material after brazing is 0.15% or less.

2. The aluminum alloy clad material according to claim 1, wherein the core material further contains, by mass %, Mg: 0.1% to 0.7%.

3. The aluminum alloy clad material according to claim 1, wherein the core material further contains, by mass %, Ti: 0.05% to 0.3%.

4. The aluminum alloy clad material according to claim 2, wherein the core material further contains, by mass %, Ti: 0.05% to 0.3%.

5. The aluminum alloy clad material according to claim 1, wherein, of natural potentials of a lowest portion of the sacrificial material and a central portion of the core material after brazing, the natural potential of the lowest portion of the sacrificial material is lower, a difference between the natural potentials is in a range of 70 to 280 mV, and a potential difference between an outermost surface and the lowest portion of the sacrificial material is 50 mV or less.

6. The aluminum alloy clad material according to claim 2, wherein, of natural potentials of a lowest portion of the sacrificial material and a central portion of the core material after brazing, the natural potential of the lowest portion of the sacrificial material is lower, a difference between the natural potentials is in a range of 70 to 280 mV, and a potential difference between an outermost surface and the lowest portion of the sacrificial material is 50 mV or less.

7. The aluminum alloy clad material according to claim 3, wherein, of natural potentials of a lowest portion of the sacrificial material and a central portion of the core material after brazing, the natural potential of the lowest portion of the sacrificial material is lower, a difference between the natural potentials is in a range of 70 to 280 mV, and a potential difference between an outermost surface and the lowest portion of the sacrificial material is 50 mV or less.

8. The aluminum alloy clad material according to claim 4, wherein, of natural potentials of a lowest portion of the sacrificial material and a central portion of the core material after brazing, the natural potential of the lowest portion of the sacrificial material is lower, a difference between the natural potentials is in a range of 70 to 280 mV, and a potential difference between an outermost surface and the lowest portion of the sacrificial material is 50 mV or less.

9. The aluminum alloy clad material according to claim 1, wherein the sacrificial material further contains, by mass %, one or two or more of Si: 0.2% to 0.8%, Cr: 0.05% to 0.5%, and Ti: 0.05% to 0.3%.

10. The aluminum alloy clad material according to claim 2, wherein the sacrificial material further contains, by mass %, one or two or more of Si: 0.2% to 0.8%, Cr: 0.05% to 0.5%, and Ti: 0.05% to 0.3%.

11. The aluminum alloy clad material according to claim 3, wherein the sacrificial material further contains, by mass %, one or two or more of Si: 0.2% to 0.8%, Cr: 0.05% to 0.5%, and Ti: 0.05% to 0.3%.

12. The aluminum alloy clad material according to claim 4, wherein the sacrificial material further contains, by mass %, one or two or more of Si: 0.2% to 0.8%, Cr: 0.05% to 0.5%, and Ti: 0.05% to 0.3%.

13. The aluminum alloy clad material according to claim 5, wherein the sacrificial material further contains, by mass %, one or two or more of Si: 0.2% to 0.8%, Cr: 0.05% to 0.5%, and Ti: 0.05% to 0.3%.

14. The aluminum alloy clad material according to claim 6, wherein the sacrificial material further contains, by mass %, one or two or more of Si: 0.2% to 0.8%, Cr: 0.05% to 0.5%, and Ti: 0.05% to 0.3%.

15. The aluminum alloy clad material according to claim 7, wherein the sacrificial material further contains, by mass %, one or two or more of Si: 0.2% to 0.8%, Cr: 0.05% to 0.5%, and Ti: 0.05% to 0.3%.

16. The aluminum alloy clad material according to claim 8, wherein the sacrificial material further contains, by mass %, one or two or more of Si: 0.2% to 0.8%, Cr: 0.05% to 0.5%, and Ti: 0.05% to 0.3%.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0104] FIG. 1 is a view illustrating a brazing sheet for flux-free brazing according to an embodiment of the present invention.

[0105] FIG. 2 is a perspective view illustrating an aluminum heat exchanger for a vehicle according to the embodiment of the present invention.

[0106] FIG. 3 is a view illustrating a brazing evaluation model in an example of the present invention.

[0107] FIG. 4 is a diagram illustrating the relationship between potential differences between an outermost surface and a lowest portion of a sacrificial material and a central portion of a core material in an example of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0108] Hereinafter, an embodiment of the present invention will be described.

[0109] An aluminum alloy is melted to be adjusted to the composition of the present invention. The melting can be performed by a semi-continuous casting method.

[0110] In the present embodiment, in order to disperse a fine MgBi 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 a brazing material.

[0111] Specifically, the solid solubility of Mg and Bi can be increased by setting the molten metal temperature to 700 C. or higher.

[0112] The obtained aluminum alloy ingot is subjected to a homogenization treatment under predetermined conditions. When the homogenization treatment temperature is low, a coarse MgBi compound is precipitated and it is difficult to obtain the distributed state of the MgBi 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.

[0113] Next, the brazing material is assembled with a core material and a sacrificial material and is subjected to hot clad rolling. At this time, in the present invention, the MgBi 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.

[0114] First, by satisfying the rolling time in a predetermined temperature range during the hot rolling, precipitation of the MgBi compound having a predetermined size defined in the present invention is promoted in an environment where dynamic strain is applied.

[0115] Specifically, the precipitation of the fine MgBi 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.

[0116] Furthermore, by controlling the equivalent strain from the start to the end of the hot rolling, a coarse MgBi crystallized product generated during the casting can be crushed and refined, and the number density thereof can be increased. Specifically, the MgBi crystallized product is sufficiently refined by adjusting a slab thickness and a finish thickness so that the equivalent strain represented by Formula (1) satisfies >5.0, thereby increasing the number density

=(2/{square root over (3)})1n(t.sub.0/t) Formula (1)

[0117] t.sub.0: Hot rolling start thickness (slab thickness)

[0118] t: Hot rolling finish thickness

[0119] 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 MgBi 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 MgBi compound is suppressed. Specifically, the precipitation of a coarse MgBi 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.

[0120] 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.

[0121] 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 MgBi 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.

[0122] The aluminum alloy clad material 1 made of the brazing sheet 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.

[0123] 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.

[0124] 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.

[0125] 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.

[0126] 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.

[0127] 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

[0128] Various brazing sheets having the compositions shown in Tables 1 and 2 and Tables 4 and 5 (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 7. In addition, - in the component indicates that the content is 0 or the amount as an inevitable impurity.

[0129] Thereafter, cold rolled sheets having a thickness of 0.30 nun 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. Moreover, as a brazing target member, a corrugated fin of an aluminum bare material (0.06 mm thickness) of A3003 alloy and H14 was prepared.

[0130] 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. in a brazing furnace in a nitrogen atmosphere (vacuum degree 100 kPa, oxygen content 30 ppm) and then cooled as it was, and the brazed state was evaluated.

[0131] Here, a heat input amount during temperature rising 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 610.sup.11 m.sup.2, a heat input amount until the completion of the brazing was set to 410.sup.10 m.sup.2, and cooling from a brazing temperature to room temperature was performed at a rate of 100 C./min.

[0132] The potential after brazing and the element concentration on the surface of the material arc affected by an element diffusion state after brazing. The element diffusion state is determined by the heat input amount if the material specifications (added components before brazing and amounts thereof) are determined. Therefore, the heat input amount is specified. The heat input amount is a parameter indicating the ease of element diffusion, and herein, is expressed as the integration of the product of the diffusion coefficient of Zn and time. The diffusion coefficient is obtained by the following formula.

Diffusion coefficient=frequency factorEXP (activation energy/(gas constanttemperature expressed in absolute temperature))

[0133] Frequency factor: 1.7710.sup.5 (m.sup.2/s)

[0134] Activation energy: 118 (kJ/mol)

[0135] The heat input amount until the completion of brazing is calculated by the heat input amount of the entire brazing process until room temperature is reached by cooling after the brazing temperature is reached.

[0136] Moreover, brazing conditions including the heat input amount are not limited to the above conditions as the present invention, and the above conditions can be used as measurement conditions for evaluation of the clad material before brazing.

[0137] The brazing conditions are not limited to the above.

[0138] For each specimen in examples, the following evaluation was performed, and the evaluation results are shown in Tables 3 and 6.

[0139] Brazability

[0140] Joint ratio

[0141] 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

[0142] Regarding the joint ratio, 90% or more was evaluated as O, and less than 90% was evaluated as X

[0143] Fillet length

[0144] A sample cut out from the core was embedded in a resin and mirror-polished, and a fillet length 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 to be measured was 20 and the average thereof was taken as the fillet length to evaluate superiority or inferiority.

[0145] In the fillet length, 800 m or more was evaluated as A, 700 m or more and less than 800 m as B, 600 m or more and less than 700 m as C, 500 m or more and less than 600 m as D, and less than 500 m as E.

[0146] Coarse primary phase Si particles

[0147] A produced brazing sheet was embedded in a resin, a cross section thereof parallel to a rolling direction was mirror-polished, and the structure thereof was revealed with Barker's solution and then observed with an optical microscope to evaluate the formation state of coarse primary phase Si in a brazing material layer. Observation was performed on a visual field of 300 m at 10 points.

[0148] A case where coarse Si particles having an equivalent circle diameter of 30 m 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.

[0149] Strength After Brazing

[0150] 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.

[0151] 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.

[0152] Corrosion Resistance

[0153] 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 mm80 nun, masked except for a sacrificial material surface, and then subjected to a corrosion test for 60 days. The corrosion test was performed using a 1% NaCl aqueous solution adjusted to a pH of 3 as a corrosion solution, and spraying for 30 minutes and setting for 90 minutes were provided as one cycle for the test (the cycle, temperature, humidity, and the like of the corrosion test are the same as SWAAT).

[0154] 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. Regarding the corrosion resistance, a case where the corrosion depth was within 20 m was evaluated as A, and a case where the corrosion depth was within the sacrificial material layer was evaluated as B. A case where the corrosion depth exceeds the sacrificial material layer and was within half of the sheet thickness was evaluated as C. Among the test materials that were penetrated in SWAAT for 60 days, a case where there was no penetration in 40 days but penetration occurred after 40 days was evaluated as D, and a case where penetration occurred in 40 days was evaluated as E.

[0155] Mg Concentration on Surface of Sacrificial Material After Brazing

[0156] 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 Mg 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 Mg concentration in a range of 5 m from the surface of the sacrificial material was taken as the Mg concentration on the surface of the sacrificial material. There are cases where the Mg concentration is detected as high due to the generation of MgO on the surface of the sacrificial material. Therefore, the average Mg concentration was calculated after excluding data in which 1.0% or more was detected.

[0157] Other Evaluation Items

[0158] Potential Difference between Lowest Portion of Sacrificial Material and Central Portion of Core Material

[0159] A sample for polarization measurement was cut out from the material subjected to the brazing equivalent heat treatment under the above brazing conditions. After masking surfaces other than the measurement surface, the sample was immersed in a 5% NaOH solution heated to 50 C. for 10 seconds, then immersed in a 30% HNO.sub.3 solution for 60 seconds, and thereafter washed with tap water or ion-exchange water. Thereafter, the natural potential (the reference electrode is a silver/silver chloride electrode) of the sample as it was without being dried was measured in a 5% NaCl aqueous solution adjusted to a pH of 3 at room temperature under air release conditions for 120 minutes. As the natural potential, an average value during 100 to 120 minutes where the value settled was obtained.

[0160] For the central portion of the core material, the above measurement was performed after the central portion of the core material was exposed by etching using NaOH or the like in advance, and the natural potential thereof was obtained.

[0161] Potential Difference Between Outermost Surface and Lowest Portion of Sacrificial Material

[0162] A sample for polarization measurement was cut out from the material subjected to the brazing equivalent heat treatment under the above brazing conditions. After masking surfaces other than the measurement surface, the sample was immersed in a 5% NaOH solution heated to 50 C. for 10 seconds, then immersed in a 30% HNO.sub.3 solution for 60 seconds, and thereafter washed with tap water or ion-exchange water. Thereafter, the natural potential (the reference electrode is a silver/silver chloride electrode) of the sample as it was without being dried was measured in a 5% NaCl aqueous solution adjusted to a pH of 3 at room temperature under air release conditions for 120 minutes. As the natural potential, an average value during 100 to 120 minutes where the value settled was obtained.

[0163] For the lowest portion of the sacrificial material, the natural potential thereof was obtained by performing the above measurement after exposing positions every 3 m from the surface of the sacrificial material by etching using NaOH or the like in advance. After obtaining a potential distribution in a cross-sectional direction, a position where the lowest natural potential was obtained was determined as the lowest portion of the sacrificial material.

[0164] The relationship between potential differences between the outermost surface and the lowest portion of the sacrificial material, and the central portion of the core material is shown in a reference schematic diagram of FIG. 4.

TABLE-US-00001 TABLE 1 Elements added to brazing material MgBi compound [wt %] Manufacturing [/10000 m.sup.2] Specimen No. Mg Si Bi Sr method Less than 5 m 5 m 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 0.8 11.0 0.20 0.0005 F 35 0 0.0005 6 1.2 11.0 0.15 0.0005 F 35 0 0.000675 7 1.2 12.0 0.15 0.05 F 35 0 0.0675 8 1.2 12.0 0.15 0.07 F 35 0 0.0945 9 1.4 11.0 0.23 0.007 H 44 0 0.01141 10 0.5 6.0 0.23 0.008 I 54 0 0.00584 11 0.3 9.0 0.20 0.007 B 34 0 0.0035 12 0.3 13.0 0.10 0.005 E 38 0 0.002 13 0.5 14.0 0.20 0.005 G 55 1 0.0035 14 0.3 11.5 0.05 0.005 I 32 0 0.00175 15 0.5 11.5 0.08 0.008 F 33 0 0.00464 16 0.5 11.5 0.23 0.006 A 40 0 0.00438 17 0.5 11.5 0.25 0.006 B 46 0 0.0045 18 0.5 12.5 0.15 0.0001 E 38 0 0.000065 19 0.5 12.5 0.15 0.0005 F 31 0 0.000325 20 0.2 12.5 0.15 0.04 I 33 0 0.014 21 0.05 12.5 0.15 0.1 E 22 0 0.02 22 0.1 12.5 0.15 0.1 E 35 0 0.025 23 0.5 11.5 0.15 0.008 E 37 0 0.0052 24 0.5 11.5 0.20 0.006 A 38 0 0.0042 25 0.5 11.5 0.20 0.007 D 43 0 0.0049 26 0.5 11.5 0.20 0.008 B 33 0 0.0056 27 0.5 11.5 0.20 0.01 F 47 0 0.007 28 1.2 11.5 0.20 0.01 B 33 0 0.014 29 1.2 11.5 0.20 0.009 J 66 1 0.0126 30 1.0 11.5 0.20 0.01 A 41 0 0.012 31 1.0 11.5 0.20 0.08 B 36 0 0.096 32 0.3 11.5 0.20 0.004 I 55 0 0.002 33 0.3 11.5 0.15 0.007 E 41 0 0.00315 34 0.3 11.5 0.15 0.005 G 33 0 0.00225 35 0.3 11.5 0.15 0.01 J 47 0 0.0045 36 0.8 11.5 0.15 0.01 I 35 0 0.0095 37 0.8 11.5 0.20 0.08 C 38 0 0.08 38 0.5 11.5 0.20 0.008 D 44 0 0.0056 39 0.5 11.5 0.15 0.01 I 38 0 0.0065 40 0.5 11.5 0.15 0.009 J 42 0 0.00585 41 0.5 11.5 0.20 0.01 H 43 0 0.007 42 0.5 11.5 0.20 0.006 A 41 0 0.0042 43 0.5 11.5 0.20 0.0002 J 66 1 0.00014 44 0.5 11.5 0.20 0.0002 J 66 1 0.00014 45 0.5 11.5 0.20 0.0002 J 66 1 0.00014 46 0.5 11.5 0.20 0.0002 J 66 1 0.00014 47 0.5 11.5 0.23 0.01 B 47 0 0.0073 48 0.5 11.5 0.12 0.01 F 33 0 0.0062 49 0.5 11.5 0.20 0.008 B 34 0 0.0056 50 0.5 11.5 0.15 0.01 G 36 0 0.0065 51 0.5 11.5 0.20 0.008 B 34 0 0.0056 52 0.5 11.5 0.20 0.008 B 34 0 0.0056 53 0.5 11.5 0.20 0.008 B 34 0 0.0056 54 0.5 11.5 0.20 0.008 B 34 0 0.0056 55 0.5 11.5 0.20 0.008 B 34 0 0.0056 56 0.5 11.5 0.20 0.008 B 34 0 0.0056 57 0.5 11.5 0.20 0.008 B 34 0 0.0056 58 0.5 11.5 0.15 0.01 G 36 0 0.0065 59 0.5 11.5 0.20 0.01 D 44 0 0.007 60 0.5 11.5 0.20 0.01 F 49 0 0.007 61 0.6 11.0 0.15 0.0005 F 35 0 0.000375 62 0.6 11.0 0.15 0.0005 F 35 0 0.000375 63 0.6 11.0 0.15 0.0005 F 35 0 0.000375 64 0.6 11.0 0.15 0.0005 F 35 0 0.000375 65 0.6 11.0 0.15 0.0005 F 35 0 0.000375 66 0.6 11.0 0.15 0.0005 F 35 0 0.000375 67 0.6 11.0 0.15 0.0005 F 35 0 0.000375 68 0.3 11.0 0.20 0.02 E 35 0 0.01 69 0.5 11.5 0.15 0.008 E 37 0 0.0052 70 0.8 11.5 0.20 0.08 C 38 0 0.08 71 0.5 11.5 0.15 0.01 G 33 0 0.0065 72 0.5 11.5 0.20 0.008 C 37 0 0.0056 73 0.5 11.5 0.20 0.007 H 44 0 0.0049 74 0.3 11.5 0.20 0.01 A 42 0 0.005

TABLE-US-00002 TABLE 2 Concentration of Mg on surface of Core material composition [wt %] sacrificial material Sacrificial material composition [wt %] Specimen No. Si Mg Mn Cu Ti Fe (wt %) Zn Si Cr Ti Mg Example 1 0.7 0.5 1.2 0.4 0.2 0.11 3 2 0.7 0.5 1.2 0.4 0.2 0.11 3 3 0.7 0.5 1.2 0.4 0.2 0.11 3 4 0.7 0.5 1.2 0.4 0.2 0.11 3 5 0.7 0.5 1.2 0.4 0.2 0.11 3 6 0.7 0.5 1.2 0.4 0.2 0.11 3 7 0.7 0.5 1.2 0.4 0.2 0.11 3 8 0.7 0.5 1.2 0.4 0.2 0.11 3 9 0.7 0.2 1.2 0.4 0.15 0.2 0.04 3 10 0.7 0.5 1.2 0.4 0.15 0.2 0.11 3 11 0.7 0.5 1.2 0.4 0.15 0.2 0.11 1.5 12 0.7 0.5 1.2 0.4 0.15 0.2 0.11 1.5 13 0.7 0.5 1.2 0.4 0.1 0.2 0.11 0.7 14 0.7 0.5 1.2 0.4 0.1 0.2 0.11 3 15 0.7 0.5 1.2 0.4 0.1 0.2 0.11 3 0.4 16 0.7 0.5 1.2 0.4 0.1 0.2 0.11 3 0.4 17 0.7 0.5 1.2 0.4 0.1 0.2 0.11 3 0.4 18 0.7 0.5 1.2 0.4 0.2 0.11 0.7 0.4 19 0.7 1.2 0.4 0.2 0.01 3 0.4 20 0.7 1.2 0.4 0.2 0.01 2 21 0.7 1.2 0.4 0.2 0.01 2 22 0.7 1.2 0.4 0.2 0.01 2 23 0.2 1.2 0.4 0.2 0.01 3 24 0.6 1.2 0.4 0.2 0.01 3 0.1 25 0.9 1.2 0.4 0.2 0.01 3 0.1 26 1.0 1.2 0.4 0.2 0.01 3 0.1 27 0.75 0.1 1.2 0.6 0.2 0.02 2 0.05 28 0.75 0.2 1.2 0.6 0.2 0.04 2 0.3 29 0.75 0.65 1.2 0.6 0.2 0.14 3 30 0.75 0.7 1.2 0.6 0.2 0.14 3 31 0.7 0.5 1.1 0.55 0.2 0.11 3 32 0.7 0.5 1.2 0.55 0.2 0.11 2 0.05 33 0.7 0.5 1.6 0.55 0.2 0.11 2 0.5 34 0.7 0.5 1.7 0.55 0.2 0.11 3 0.2 35 0.85 0.5 1.2 0.1 0.2 0.11 0.5 0.2 36 0.85 0.5 1.2 0.15 0.2 0.11 0.5 0.2 37 0.85 0.5 1.2 1.0 0.2 0.11 0.5 0.2 38 0.5 0.5 1.2 0.4 0.1 0.11 3 0.2 39 0.5 0.5 1.2 0.4 0.12 0.11 3 0.3 40 0.5 0.5 1.2 0.4 0.4 0.11 3 0.2 41 0.5 1.2 0.4 0.5 0.11 3 0.1 42 0.7 1.2 0.4 0.2 0.11 0.6 0.1 43 0.7 1.2 0.4 0.2 0.11 3 0.1 44 0.7 1.2 0.4 0.2 0.11 3 45 0.7 0.5 1.2 0.4 0.2 0.13 3 0.03 46 0.7 0.4 1.2 0.4 0.2 0.14 6.0 0.1 47 0.7 1.2 0.4 0.2 0.11 3 48 0.7 1.2 0.4 0.2 0.11 3 49 0.7 1.2 0.4 0.2 0.11 2 0.2 50 0.7 1.2 0.4 0.2 0.11 2 0.8 51 0.7 1.2 0.4 0.2 0.11 2 0.3 52 0.7 1.2 0.4 0.2 0.2 0.11 2 0.3 0.2 53 0.7 0.5 1.2 0.4 0.2 0.2 0.11 2 0.3 0.2 0.2 54 0.7 0.5 1.2 0.4 0.2 0.2 0.11 2 0.3 0.2 0.2 55 0.7 0.5 1.2 0.4 0.2 0.2 0.11 2 0.3 0.2 56 0.7 0.5 1.2 0.4 0.08 0.2 0.11 2 0.3 0.2 57 0.7 0.5 1.2 0.4 0.08 0.2 0.11 2 0.3 58 0.7 0.5 1.2 0.4 0.2 0.2 0.11 2 59 0.75 0.2 1.2 0.6 0.2 0.2 0.04 3 0.3 60 0.75 0.2 1.2 0.6 0.2 0.2 0.04 3 0.3 61 0.7 0.5 1.2 0.4 0.2 0.2 0.11 0.5 62 0.7 0.5 1.2 0.4 0.2 0.2 0.11 1 63 0.7 0.5 1.2 0.4 0.2 0.2 0.11 2 64 0.7 0.5 1.2 0.4 0.2 0.2 0.11 3 65 0.7 0.5 1.2 0.4 0.2 0.2 0.11 4 66 0.7 0.5 1.2 0.4 0.2 0.2 0.11 5 67 0.7 0.5 1.2 0.4 0.2 0.2 0.11 6.0 68 0.7 0.2 1.4 0.4 0.2 0.2 0.04 3 69 0.2 1.2 0.4 0.2 0.01 3 70 0.85 0.5 1.2 1.0 0.2 0.11 1 0.2 71 0.4 0.5 1.2 0.2 0.2 0.11 3 72 0.5 1.0 0.4 0.2 0.01 3 73 0.7 1.2 0.08 0.15 0.2 0.01 3 0.2 74 0.1 1.4 0.9 0.15 0.2 0.01 3 0.2

TABLE-US-00003 TABLE 3 Potential difference Corrosion Brazability between surface resistance Joint Fillet Coarse Si Potential and lowest portion Corrosion Strength after brazing Specimen No. ratio length particles difference (reversal potential) depth [MPa] Evaluation Example 1 D A 240 20 A 182 B 2 C A 240 20 A 185 B 3 B A 240 20 A 185 B 4 B A 240 20 A 187 B 5 A A 240 20 A 188 B 6 C A 240 20 A 190 B 7 C A 240 20 A 190 B 8 C B 240 20 A 190 B 9 D A 250 15 A 178 C 10 D A 240 20 A 187 B 11 B A 150 20 B 186 B 12 B A 150 20 B 186 B 13 D A 100 20 C 187 B 14 C A 240 20 A 186 B 15 B A 240 20 A 188 B 16 B A 240 20 A 188 B 17 C A 240 20 A 188 B 18 B B 100 20 C 188 B 19 B A 240 8 A 166 C 20 B A 190 7 A 163 C 21 D A 180 10 A 162 C 22 B A 180 6 A 162 C 23 B A 240 7 A 152 C 24 B A 240 9 A 160 C 25 B A 240 8 A 172 C 26 C A 240 7 A 175 C 27 A A 200 10 A 178 C 28 B A 200 15 A 186 B 29 A A 210 30 B 206 A 30 B A 210 35 B 207 A 31 B B 220 20 A 193 A 32 A A 200 20 A 191 A 33 B A 200 20 A 197 A 34 B A 220 20 A 199 A 35 A A 120 20 B 180 C 36 B A 120 20 B 184 B 37 B B 80 20 C 201 A 38 B A 240 20 A 178 C 39 B A 240 20 A 180 B 40 B A 240 20 A 181 B 41 A A 240 20 A 159 C 42 B A 85 20 C 164 C 43 A A 250 20 A 164 C 44 A A 260 25 A 164 C 45 A A 230 30 A 187 B 46 A A 220 35 C 182 B 47 A A 240 20 A 164 C 48 B A 240 20 A 164 C 49 B A 210 20 A 165 C 50 B A 210 20 A 168 C 51 B A 210 20 A 165 C 52 B A 210 20 A 165 C 53 B A 210 20 A 188 B 54 B A 210 20 A 188 B 55 B A 210 20 A 188 B 56 B A 210 20 A 188 B 57 B A 210 20 A 188 B 58 B A 210 20 A 187 A 59 A A 230 15 A 182 A 60 A A 230 15 A 182 A 61 B A 80 10 C 187 B 62 B A 130 20 B 187 A 63 B A 170 20 B 187 A 64 B A 240 20 A 187 A 65 B A 245 20 A 187 A 66 B A 250 20 A 187 A 67 B A 270 20 A 187 A 68 B A 260 15 A 175 A 69 B A 240 7 A 151 C 70 B B 80 20 D 210 A 71 C A 240 20 A 145 C 72 C A 260 10 A 149 C 73 C A 260 7 A 152 C 74 C A 260 9 D 162 C

TABLE-US-00004 TABLE 4 Elements added to brazing material MgBi compound [wt %] Manufacturing [/10000 m.sup.2] Specimen No. Mg Si Bi Sr method Less than 5 m 5 m or more (Bi + Mg) Sr Comparative 1 0.02 11.0 0.11 0.0005 B 16 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 Cannot be manufactured and evaluated 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 Cannot be manufactured and evaluated 0.105 9 0.5 11.5 0.15 0.005 I 36 0 0.00325 10 0.5 11.5 0.20 0.006 C Cannot be manufactured and evaluated 0.0042 11 0.3 11.5 0.20 0.005 D 45 0 0.0025 12 0.3 11.5 0.20 0.01 B Cannot be manufactured and evaluated 0.005 13 1.2 11.5 0.20 0.08 B Cannot be manufactured and evaluated 0.112 14 1.2 11.5 0.15 0.09 B Cannot be manufactured and evaluated 0.1215 15 0.3 11.5 0.15 0.01 K 12 3 0.0045 16 0.3 11.5 0.15 0.007 N 19 5 0.00315 17 0.5 11.5 0.20 0.007 O 16 4 0.0049 18 0.5 11.5 0.20 0.01 L 18 7 0.007 19 0.5 11.5 0.15 0.008 M 15 6 0.0052 20 0.5 11.5 0.15 0.01 K 13 5 0.0065 21 1.0 11.5 0.12 0.006 N 18 3 0.00672 22 1.6 11.5 0.23 0.007 H 44 0 0.01281 23 0.03 11.0 0.15 0.0005 E 23 0 0.00009 24 0.6 11.0 0.15 0.0005 F 35 0 0.000375 25 0.6 11.0 0.15 0.0005 F 35 0 0.000375 26 0.5 11.5 0.20 0.008 C 37 0 0.0056 27 0.5 11.5 0.20 0.007 H 44 0 0.0049 28 0.5 11.5 0.15 0.01 G 33 0 0.0065 29 0.3 11.5 0.20 0.01 A 42 0 0.005 Reference 1 0.5 11.5 0.50 0.0007 C 38 0 0.0007 Example 2 0.5 11.5 0.15 0.25 C 40 0 0.1625 3 0.3 10.0 0.20 0.01 B 40 0 0.005

TABLE-US-00005 TABLE 5 Concentration of Mg on surface of Core material composition [wt %] sacrificial material Sacrificial material composition [wt %] Specimen No. Si Mg Mn Cu Ti Fe (wt %) Zn Si Cr Ti Mg Comparative 1 0.7 0.7 1.2 0.4 0.2 0.22 3 0.1 Example 2 0.7 0.7 1.2 0.4 0.2 0.3 3 0.2 3 0.7 0.7 1.2 0.4 0.2 0.23 3 0.15 4 0.7 0.5 1.2 0.4 0.2 Cannot be evaluated 3 5 0.7 0.5 1.2 0.4 0.2 0.11 3 6 0.7 1.2 0.4 0.2 0.06 3 0.5 0.08 7 0.7 0.5 1.2 0.4 0.2 0.11 3 0.5 8 0.7 1.2 0.4 0.2 Cannot be evaluated 3 0.5 9 1.2 0.5 1.2 0.2 0.2 0.11 3 0.1 0.7 0.2 1.8 0.4 0.2 0.7 Cannot be evaluated 3 0.1 11 0.5 0.3 1.2 0.4 0.15 0.08 0.06 3 0.2 12 0.5 0.3 1.2 0.4 0.15 0.7 Cannot be evaluated 3 0.5 13 0.7 0.5 1.7 0.4 0.2 0.4 0.2 0.1 14 0.7 0.5 1.5 0.4 0.5 0.2 6.0 0.1 0.03 15 0.7 0.5 1.2 0.4 0.2 0.11 3 16 0.7 0.5 1.2 0.4 0.2 0.11 3 0.2 17 0.7 0.5 1.2 0.4 0.2 0.11 3 18 0.7 0.5 1.2 0.4 0.2 0.11 3 19 0.7 0.5 1.2 0.4 0.2 0.11 3 0.4 20 0.7 0.5 1.2 0.4 0.2 0.11 3 0.3 21 0.7 0.5 1.2 0.4 0.2 0.11 3 0.4 22 0.7 0.7 1.2 0.4 0.2 0.20 3 0.1 23 0.7 0.2 1.2 0.4 0.2 0.04 3 24 0.7 0.5 1.2 0.4 0.1 0.2 0.11 0.4 25 0.7 0.2 1.2 0.4 0.1 0.2 0.11 7 26 0.5 0.8 0.4 0.2 0.01 3 27 0.7 1.2 0.02 0.15 0.2 0.01 3 0.2 28 0.15 0.5 1.2 0.2 0.2 0.11 3 29 0.1 1.4 1.2 0.15 0.2 0.01 3 0.2 Reference 1 0.7 0.5 1.2 0.4 0.2 Cannot be evaluated 3 0.4 0.02 Example 2 0.7 0.5 1.2 0.4 0.2 3 0.4 0.1 0.09 3 0.7 0.5 1.2 1.2 0.2 0.4

TABLE-US-00006 TABLE 6 Potential difference Corrosion Brazability between surface resistance Joint Fillet Coarse Si Potential and lowest portion Corrosion Strength after brazing Specimen No. ratio length particles difference (reversal potential) depth [MPa] Evaluation Comparative 1 X E A 180 60 E 193 A Example 2 X E A 130 80 E 201 A 3 E A 185 55 E 196 A 4 Evaluation material cannot be manufactured and evaluated. 5 E A 240 20 A 185 B 6 X E A 240 20 A 166 C 7 X E C 240 20 A 166 C 8 Evaluation material cannot be manufactured and evaluated. 9 Poor brazing due to generation of 240 20 A 198 A significant erosion 10 Evaluation material cannot be manufactured and evaluated. 11 A A 250 15 A 168 C 12 Evaluation material cannot be manufactured and evaluated. 13 Evaluation material cannot be manufactured and evaluated. 14 Evaluation material cannot be manufactured and evaluated. 15 E A 240 20 A 186 B 16 E A 240 20 A 187 B 17 E A 240 20 A 187 B 18 E A 240 20 A 187 B 19 E A 240 20 A 188 B 20 E A 240 20 A 188 B 21 E A 240 20 A 191 B 22 X E A 230 55 E 197 A 23 X E A 250 15 A 171 C 24 C A 65 20 E 187 B 25 C A 300 20 E 174 C 26 C A 260 10 A 144 D 27 C A 260 7 A 143 D 28 C A 240 2 A 140 D 29 C A 220 9 E 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.

TABLE-US-00007 TABLE 7 (Brazing material) Casting Homogenization Hot rolling condition condition condition Rolling time Molten metal Temperature between 400 C. Equivalent Finish temperature and time and 500 C. strain temperature Cooling rate Specimen No. ( C.) ( C., h) (min) ( 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

[0165] 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.