Aluminum alloy brazing sheet
An aluminum alloy brazing sheet may include a sacrificial material having a function of a brazing material on at least one surface of a core material, wherein the sacrificial material has a composition containing: in a mass %, 2% to 5% of Si; 3% to 5% of Zn; and an Al balance with inevitable impurities the core material is made of an Al—Mn-based alloy, an in the core material before brazing, Al—Mn based secondary particles having an equivalent circle diameter of 100 to 400 nm are distributed with a number density of 0.3 to 5 particles/μm 2 .
1. An aluminum alloy brazing sheet, comprising:
a sacrificial material having a function of a brazing material on at least one surface of a core material,
wherein the sacrificial material has a composition comprising, in mass %:
2.0% to 5.0% of Si;
3.0% to 5.0% of Zn; and
Al,
wherein the core material comprises an Al—Mn-based alloy, and
in the core material before brazing, Al—Mn-based secondary particles having an equivalent circle diameter of 150 to 400 nm are distributed with a number density of 0.3 to 5 particles/μm 2 .
2. The sheet of claim 1 , wherein when the sheet is subjected to a heat treatment equivalent to brazing in which a temperature is raised from 590° C. to 615° C., a Mn/Si ratio is 0.5 to 5.0 in a region of 50 μm from the sacrificial material/core material interface.
3. The sheet of claim 1 , wherein the core material comprises, in mass %:
0.3% to 2.0% of Mn;
0.05% to 1.0% of Si;
0.01% to 1.0% of Cu; and
0.1% to 0.7% of Fe.
4. The sheet of claim 1 , wherein the sacrificial material further comprises, in mass %:
0.1% to 1.0% of Mn; and/or
0.1% to 0.7% of Fe.
5. The sheet of claim 1 , wherein when the sheet is subjected to a heat treatment equivalent to brazing in which a temperature is raised from 590° C. to 615° C., an eutectic filler and a primary filler are formed in the sacrificial material,
wherein after the heat treatment, a pitting potential is less noble in an order of
the eutectic filler,
the primary filler, and
the sacrificial material/core material interface, and
wherein after the heat treatment, a potential difference between a most noble layer in the sacrificial material and a least noble layer in the core material is 50 to 200 mV.
6. The sheet of claim 2 , wherein the core material comprises, in mass %:
0.3% to 2.0% of Mn;
0.05% to 1.0% of Si;
0.01% to 1.0% of Cu; and
0.1% to 0.7% of Fe.
7. The sheet of claim 2 , wherein the sacrificial material further comprises, in mass %:
0.1% to 1.0% of Mn; and/or
0.1% to 0.7% of Fe.
8. The sheet of claim 3 , wherein the sacrificial material further comprises, in mass %:
0.1% to 1.0% of Mn; and/or
0.1% to 0.7% of Fe.
9. The sheet of claim 6 , wherein the sacrificial material further comprises, in mass %:
0.1% to 1.0% of Mn; and/or
0.1% to 0.7% of Fe.
10. The sheet of claim 2 , wherein when the sheet is subjected to a heat treatment equivalent to brazing in which a temperature is raised from 590° C. to 615° C., an eutectic filler and a primary filler are formed in the sacrificial material,
wherein after the heat treatment, a pitting potential is less noble in an order of
the eutectic filler,
the primary filler, and
the sacrificial material/core material interface, and
wherein after the heat treatment, a potential difference between a most noble layer in the sacrificial material and a least noble layer in the core material is 50 to 200 mV.
11. The sheet of claim 3 , wherein when the sheet is subjected to a heat treatment equivalent to brazing in which a temperature is raised from 590° C. to 615° C., an eutectic filler and a primary filler are formed in the sacrificial material,
wherein after the heat treatment, a pitting potential is less noble in an order of
the eutectic filler,
the primary filler, and
the sacrificial material/core material interface, and
wherein after the heat treatment, a potential difference between a most noble layer in the sacrificial material and a least noble layer in the core material is 50 to 200 mV.
12. The sheet of claim 4 , wherein when the sheet is subjected to a heat treatment equivalent to brazing in which a temperature is raised from 590° C. to 615° C., an eutectic filler and a primary filler are formed in the sacrificial material,
wherein after the heat treatment, a pitting potential is less noble in an order of
the eutectic filler,
the primary filler, and
the sacrificial material/core material interface, and
wherein after the heat treatment, a potential difference between a most noble layer in the sacrificial material and a least noble layer in the core material is 50 to 200 mV.
13. The sheet of claim 6 , wherein when the sheet is subjected to a heat treatment equivalent to brazing in which a temperature is raised from 590° C. to 615° C., an eutectic filler and a primary filler are formed in the sacrificial material,
wherein after the heat treatment, a pitting potential is less noble in an order of
the eutectic filler,
the primary filler, and
the sacrificial material/core material interface, and
wherein after the heat treatment, a potential difference between a most noble layer in the sacrificial material and a least noble layer in the core material is 50 to 200 mV.
14. The sheet of claim 7 , wherein when the sheet is subjected to a heat treatment equivalent to brazing in which a temperature is raised from 590° C. to 615° C., an eutectic filler and a primary filler are formed in the sacrificial material,
wherein after the heat treatment, a pitting potential is less noble in an order of
the eutectic filler,
the primary filler, and
the sacrificial material/core material interface, and
wherein after the heat treatment, a potential difference between a most noble layer in the sacrificial material and a least noble layer in the core material is 50 to 200 mV.
15. The sheet of claim 8 , wherein when the sheet is subjected to a heat treatment equivalent to brazing in which a temperature is raised from 590° C. to 615° C., an eutectic filler and a primary filler are formed in the sacrificial material,
wherein after the heat treatment, a pitting potential is less noble in an order of
the eutectic filler,
the primary filler, and
the sacrificial material/core material interface, and
wherein after the heat treatment, a potential difference between a most noble layer in the sacrificial material and a least noble layer in the core material is 50 to 200 mV.
16. The sheet of claim 9 , wherein when the sheet is subjected to a heat treatment equivalent to brazing in which a temperature is raised from 590° C. to 615° C., an eutectic filler and a primary filler are formed in the sacrificial material,
wherein after the heat treatment, a pitting potential is less noble in an order of
the eutectic filler,
the primary filler, and
the sacrificial material/core material interface, and
wherein after the heat treatment, a potential difference between a most noble layer in the sacrificial material and a least noble layer in the core material is 50 to 200 mV.
17. The sheet of claim 1 , wherein the sacrificial material comprises 2.5 mass % to 5.0 mass % of Si.
18. The sheet of claim 1 , wherein the sacrificial material comprises the Al, the Si, and the Zn, inevitable impurities, and optionally Mn in a range of from 0.1 to 1.0 mass % and/or Fe in a range of from 0.1 to 0.7 mass %.
19. The sheet of claim 1 , wherein the sacrificial material comprises 2.0 mass % to 4.0 mass % of Si.
20. The sheet of claim 1 , wherein when an inverted T-shaped test is performed using the sheet having an upper surface as the sacrificial material for a horizontal material and using an A3003 alloy for a vertical material, unjoined parts are not formed and erosion of 150 μm or more from the sacrificial material/core material interface in the core material direction does not occur.