Aluminium brazing sheet material for fluxless brazing
View Patent ↗A brazing sheet material including a core alloy layer bonded on at least one side with an aluminum brazing clad layer or layers forming a filler material of a 4000-series aluminum alloy. The core layer is made from an aluminum alloy having (in wt. %): Mg 1.0 to 3.0, Mn 0 to 1.8, Cu 0 to 0.8, Si 0 to 0.7, Fe 0 to 0.7, optionally one or more elements selected from the group (Zr, Cr, Hf, T), Zn 0 to 0.5, impurities and aluminum. The filler material forms a 4000-series aluminum alloy further including one or more wetting elements selected from Bi 0.03-0.5, Pb 0.03-0.5, Sb 0.03-0.5, Li 0.03-0.5, Se 0.03-0.5, Y 0.03-0.05, Th 0.03-0.05, wherein the sum of these elements being 0.5% or less.
1. A brazing sheet material comprising of a core alloy layer bonded on at least one side with an aluminium brazing clad layer or layers forming a filler material of a 4000-series aluminium alloy, wherein the core layer is made from an aluminium alloy comprising, in wt. %:
Mg
2.0 to 3.0
Mn
0 to 1.8
Cu
0 to 0.1
Si
0 to 0.7
Fe
0 to 0.7,
optionally one or more elements selected from the group consisting of:
Zr 0.04 to 0.4, Cr 0.04 to 0.4, Hf 0.04 to 0.4, and Ti 0.01 to 0.3,
Zn 0 to 0.5,
unavoidable impurities and balance aluminium,
and wherein the filler material comprises, in wt. %:
Si
6 to 14
Mg
0.02 to 0.5
Bi
0.05 to 0.5
Fe
0 to 0.8
Zn
0 to 0.4
Mn
0 to 0.3
Cu
0 to 0.3
Ti
0 to 0.2,
unavoidable impurities and balance aluminium.
2. A brazing sheet material according to claim 1 , wherein the core alloy has a Mg content of 2.0 to 2.8%.
3. A brazing sheet material according to claim 1 , wherein the core alloy has a Si content of 0.1 to 0.7%.
4. A brazing sheet material according to claim 1 , wherein the core alloy has a Mg content of 2.3% to 3.0%.
5. A brazing sheet material according to claim 1 , wherein the core alloy has a Si content of 0.1% to 0.6%.
6. A brazing sheet material according to claim 1 , wherein the core alloy is on one side bonded with the filler material, and bonded on the other side with a waterside liner material.
7. A brazing sheet material according to claim 1 , wherein the filler material has a Si content of 9 to 12%.
8. A brazing sheet material according to claim 1 , wherein the core alloy is on one side bonded with the filler material, and bonded on the other side with an aluminium brazing clad layer of an AA4000-series aluminium alloy.
9. A brazing sheet material according to claim 1 , wherein the brazing sheet material is devoid of a diffusion barrier formed by an interliner layer positioned between the core alloy layer and the brazing clad layer.
10. A method of manufacturing an article joined by brazing or an assembly of brazed components, comprising the steps of:
(a) providing the components to be brazed together of which at least one is made from an aluminium brazing sheet material according to claim 1 ;
(b) assembling the components into an assembly;
(c) brazing the assembly without applying brazing flux onto the assembly of components, and brazing the whole assembly in an inert gas atmosphere at a brazing temperature;
(d) cooling of the brazed assembly.
11. A brazing sheet material according to claim 1 , wherein the core alloy has a Fe content of 0.07% to 0.7%.
12. A brazing sheet material according to claim 1 , wherein the core alloy has a Fe content of 0.07% to 0.4%.
13. A brazing sheet material according to claim 1 , wherein the core alloy has a Mn content in a range of 0.5% to 1.8%.
14. A brazing sheet material according to claim 1 , wherein the core alloy has a Mn content in a range of 0.5% to 1.0%.
15. A brazing sheet material according to claim 1 , wherein the filler material has a Bi content in the range of 0.12% to 0.35%.
16. A brazing sheet material according to claim 1 , wherein the filler material has a Mg content in the range of 0.15% to 0.3%.
17. A brazing sheet material according to claim 1 , wherein the filler has an excess Mg-content of 0.07% or less with respect to stoichiometric composition of Bi2Mg3.
18. A brazing sheet material according to claim 1 , wherein the filler material has a Cu content of 0 to 0.05%.
19. A brazing sheet material according to claim 1 , wherein the core layer is made from an aluminium alloy comprising, in wt. %:
Mg
2.3 to 3.0,
Mn
0.5 to 1.8,
Cu
0 to 0.1,
Si
0.1 to 0.7,
Fe
0.07 to 0.4,
one or more elements selected from the group consisting of:
Zr 0.04 to 0.4, Cr 0.04 to 0.4, Hf 0.04 to 0.4, and Ti 0.01 to 0.3, and
Zn 0 to 0.5,
unavoidable impurities, and balance aluminium,
and wherein the filler material comprises, in wt. %:
Si
9 to 12,
Mg
0.15 to 0.3,
Bi
0.12 to 0.35,
Fe
0 to 0.6,
Zn
0 to 0.4,
Mn
0 to 0.1,
Cu
0.05 to 0.3,
Ti
0 to 0.15,
with the proviso that there are one or more elements from the group consisting of Zn 0.5 to 5, Sn 0.2 to 1, and In 0.1 to 1;
wherein the filler material is free of Na, K, and Ca;
unavoidable impurities and balance aluminium.
20. A brazing sheet material according to claim 1 , wherein the core has 0.06 to 0.4% Hf.
21. A brazing sheet material according to claim 1 , wherein the core has 0.2 to 0.3% Ti.
22. The method, according to claim 10 , wherein the article is a heat exchanger.
23. A brazing sheet material according to claim 1 , wherein the core alloy has a Mg content of 2.3% to 3.0%, wherein the filler material is a single layer of filler material, wherein the brazing sheet consists of the layer of the filler material bonded with the core alloy.
24. A brazing sheet material according to claim 23 , wherein the filler material has a Mg content of 0.3% to 0.5%.