ALUMINUM BRAZING SHEET AND METHOD FOR FLUX-FREE BRAZING OF ALUMINUM MEMBERS
An aluminum brazing sheet having a multi-layer structure of two layers or more, an aluminum alloy brazing material being located on an outermost surface by being cladded on one surface or both surfaces of a core material, and the aluminum brazing sheet being applied to brazing in which the aluminum brazing sheet is bonded to a member to be brazed made of aluminum or an aluminum alloy without using a flux in a non-oxidizing atmosphere without decompression. The brazing material is made of an Al—Si—Mg—Sn brazing material containing, by mass %, 0.01% to 2.0% of Mg, 1.5% to 14% of Si, and 0.005% to 1.5% of Sn, and in observation in a surface direction before brazing, there are more than 10 Mg—Sn compounds with a circle equivalent diameter of 0.01 μm or more and less than 5.0 μm in the Al—Si—Mg—Sn brazing material per 10000 μm 2 field of view.
1 . An aluminum brazing sheet having a multi-layer structure of at least two layers or more, an aluminum alloy brazing material being located on an outermost surface by being cladded on one surface or both surfaces of a core material, and the aluminum brazing sheet being applied to brazing in which the aluminum brazing sheet is bonded to a member to be brazed made of aluminum or an aluminum alloy without using a flux in a non-oxidizing atmosphere without decompression, wherein:
the brazing material is made of an Al—Si—Mg—Sn brazing material containing, by mass %, 0.01% to 2.0% of Mg, 1.5% to 14% of Si, and 0.005% to 1.5% of Sn, and
in observation in a surface direction before brazing, there are more than 10 Mg—Sn compounds with a circle equivalent diameter of 0.01 μm or more and less than 5.0 μm in the Al—Si—Mg—Sn brazing material per 10000 μm 2 field of view.
2 . The aluminum brazing sheet according to claim 1 , wherein:
in observation in a surface direction before brazing, there are less than 5 Sn particles with a circle equivalent diameter of 5.0 μm or more in the Al—Si—Mg—Sn brazing material per 10000 μm 2 field of view.
3 . The aluminum brazing sheet according to claim 1 , wherein an atomic ratio of Mg to Sn in the Al—Si—Mg—Sn brazing material, Mg/Sn, is 2 or more.
4 . The aluminum brazing sheet according to claim 1 , wherein a Ca content in impurities of the Al—Si—Mg—Sn brazing material is 100 ppm or less by a mass ppm.
5 . The aluminum brazing sheet according to claim 1 , wherein a Sr content in impurities of the Al—Si—Mg—Sn brazing material is 0.02% or less by a mass %.
6 . The aluminum brazing sheet according to claim 1 , wherein the Al—Si—Mg—Sn brazing material further comprises 0.1% to 9.0% of Zn by mass %.
7 . The aluminum brazing sheet according to claim 1 , wherein:
the core material has a composition comprising:
one or more of, by mass %,
0.05% to 1.2% of Si,
0.01% to 2.0% of Mg,
0.1% to 2.5% of Mn,
0.01% to 2.5% of Cu,
0.05% to 1.0% of Fe,
0.01% to 0.3% of Zr,
0.01% to 0.3% of Ti,
0.01% to 0.5% of Cr,
0.005% to 1.5% of Bi, and
0.1% to 9.0% of Zn; and
an Al balance comprising inevitable impurities.
8 . The aluminum brazing sheet according to claim 1 , wherein:
the core material has a composition comprising:
by mass %,
0.05% to 1.2% of Si;
0.01% to 2.0% of Mg;
one or more of, by mass %,
0.1% to 2.5% of Mn,
0.01% to 2.5% of Cu,
0.05% to 1.0% of Fe,
0.01% to 0.3% of Zr,
0.01% to 0.3% of Ti,
0.01% to 0.5% of Cr,
0.005% to 1.5% of Bi, and
0.1% to 9.0% of Zn; and
an Al balance comprising inevitable impurities.
9 . A method of flux-free brazing of aluminum members, the method comprising:
bonding between aluminum members using the aluminum brazing sheet of claim 1 without using a flux in a non-oxidizing gas atmosphere without decompression with an oxygen concentration of 100 ppm or less.
10 . The method of flux-free brazing of aluminum members according to claim 9 , wherein the bonding is performed at a heating temperature of 559° C. to 630° C.
11 . The aluminum brazing sheet according to claim 2 , wherein an atomic ratio of Mg to Sn in the Al—Si—Mg—Sn brazing material, Mg/Sn, is 2 or more.
12 . The aluminum brazing sheet according to claim 2 , wherein a Ca content in impurities of the Al—Si—Mg—Sn brazing material is 100 ppm or less by a mass ppm.
13 . The aluminum brazing sheet according to claim 2 , wherein a Sr content in impurities of the Al—Si—Mg—Sn brazing material is 0.02% or less by a mass %.
14 . The aluminum brazing sheet according to claim 2 , wherein the Al—Si—Mg—Sn brazing material further comprises 0.1% to 9.0% of Zn by mass %.
15 . The aluminum brazing sheet according to claim 2 , wherein
the core material has a composition comprising:
one or more of, by mass %,
0.05% to 1.2% of Si,
0.01% to 2.0% of Mg,
0.1% to 2.5% of Mn,
0.01% to 2.5% of Cu,
0.05% to 1.0% of Fe,
0.01% to 0.3% of Zr,
0.01% to 0.3% of Ti,
0.01% to 0.5% of Cr,
0.005% to 1.5% of Bi, and
0.1% to 9.0% of Zn; and
an Al balance comprising inevitable impurities.
16 . The aluminum brazing sheet according to claim 2 , wherein
the core material has a composition comprising:
by mass %,
0.05% to 1.2% of Si;
0.01% to 2.0% of Mg;
one or more of, by mass %,
0.1% to 2.5% of Mn,
0.01% to 2.5% of Cu,
0.05% to 1.0% of Fe,
0.01% to 0.3% of Zr,
0.01% to 0.3% of Ti,
0.01% to 0.5% of Cr,
0.005% to 1.5% of Bi, and
0.1% to 9.0% of Zn; and
an Al balance comprising inevitable impurities.
17 . A method of flux-free brazing of aluminum members, the method comprising:
bonding between aluminum members using the aluminum brazing sheet of claim 2 without using a flux in a non-oxidizing gas atmosphere without decompression with an oxygen concentration of 100 ppm or less.
18 . The method of flux-free brazing of aluminum members according to claim 17 , wherein the bonding is performed at a heating temperature of 559° C. to 630° C.