Multi-layered brazing sheet
View Patent ↗A multi-layered brazing sheet with improved long life corrosion resistance achieved by balancing the Zn, Cu, Mn, Si and Mg content of the core and interliner alloy. The brazing sheet has a core of a 3xxx alloy, an inner braze cladding of a 4xxx alloy, and between core and inner braze cladding an interliner of a 3xxx alloy. The 3xxx alloy of the core has 0.55-1.0 wt % Cu, 0.7-1.8 wt % Mn, <0.3 wt % Mg, <0.4 wt % Zn. The 3xxx alloy of the interliner has <0.25 wt % Cu, 0.5-1.5 wt % Mn, <0.3 wt % Mg, 0.1-5.0 wt % Zn. A 1xxx or 7xxx alloy could be used for the interliner instead of the 3xxx alloy.
1. A multi-layer brazing sheet comprising:
a core of a 3xxx alloy,
an inner braze cladding of a 4xxx alloy, and
between core and inner braze cladding an interliner comprising an interliner alloy selected from the group consisting of a 3xxx, 1xxx and 7xxx alloy, wherein the interliner has a lower level of Mn than the core, and
wherein the 3xxx alloy of the core comprises:
0.55-1.0 wt % Cu
0.65-1.8 wt % Mn
<0.3 wt % Mg
<0.4 wt % Zn
<1.0 wt % Si
<0.7 wt % Fe
and optionally one or more of
<0.3 wt % Cr
<0.02 wt % Ti,
and one or more of V, Zr, In, Sc, Sn, each in a range of up to 0.5%, balance aluminium and unavoidable impurities, and
wherein the interliner alloy comprises 0.1-5.0 wt % Zn, wherein if the interliner alloy is 3xxx then the 3xxx interliner alloy further comprises 0.5 to 1.5 wt % Mn.
2. The brazing sheet according to claim 1 , wherein the interliner is made of 3xxx alloy comprising:
<0.25 wt % Cu
0.5-1.5 wt % Mn
<0.3 wt % Mg 0.1-5.0 wt % Zn
<1.0 wt % Si
<0.7 wt % Fe
balance aluminium and unavoidable impurities.
3. The brazing sheet according to claim 1 , wherein the 3xxx alloy of the core comprises <0.5 wt % Fe.
4. The brazing sheet according to claim 1 , wherein the 3xxx alloy of the core comprises 0.55-0.8 wt % Cu.
5. The brazing sheet according to claim 1 , wherein the 3xxx alloy of the core comprises 0.65-1.5 wt % Mn.
6. The brazing sheet according to claim 1 , wherein the 3xxx alloy of the core comprises 0.65-1.2 wt % Mn.
7. The brazing sheet according to claim 1 , wherein the 3xxx alloy of the core comprises <0.1 wt % Mg.
8. The brazing sheet according to claim 1 , wherein the 3xxx alloy of the core comprises <0.05 wt % Mg.
9. The brazing sheet according to claim 1 , wherein the 3xxx alloy of the core comprises <0.15 wt % Cr.
10. The brazing sheet according to claim 1 , wherein the interliner is made of 3xxx alloy comprising <0.7 wt % Si.
11. The brazing sheet according to claim 1 , wherein the interliner is made of 3xxx alloy comprising <0.4 wt % Si.
12. The brazing sheet according to claim 1 , wherein the interliner is made of 3xxx alloy comprising <0.5 wt % Fe.
13. The brazing sheet according to claim 1 , wherein the interliner is made of 3xxx alloy comprising <0.2 wt % Cu.
14. The brazing sheet according to claim 1 , wherein the interliner is made of 3xxx alloy comprising 0.5-1.0 wt % Mn.
15. The brazing sheet according to claim 1 , wherein the interliner is made of 3xxx alloy comprising <0.1 wt % Mg.
16. The brazing sheet according to claim 1 , wherein the interliner is made of 3xxx alloy comprising 0.5-3.0 wt % Zn.
17. The brazing sheet according to claim 1 , wherein the interliner alloy is a 1xxx alloy with a Zn content in the range of 0.1-2.0 wt %.
18. The brazing sheet according to claim 1 wherein the brazing sheet further comprises an outer braze cladding.
19. The brazing sheet according to claim 18 , wherein a further interliner is provided between the core and outer braze cladding.
20. The brazing sheet according to claim 18 , wherein the inner and/or outer braze cladding is made of a 4xxx alloy with Si<15 wt %.
21. The brazing sheet according to claim 18 , wherein the inner and/or outer braze cladding is made of a 4xxx alloy with Si 4-15 wt % and with Cu<0.3 wt %.
22. The brazing sheet according to claim 18 , wherein successive layers of the brazing sheet with respect to the total thickness of the multi-layered brazing sheet have the following thickness ratio:
outer braze cladding
5-15%
core
60-85%
interliner
5-30%
inner braze cladding
5-15%.
23. The brazing sheet according to claim 1 , wherein successive layers of the brazing sheet with respect to the total thickness of the multi-layered brazing sheet have the following thickness ratio:
core
60-85%
interliner
5-30%
inner braze cladding
5-15%.
24. Brazed assembly comprising one or more tubes made from the multi-layered brazing sheet product according to claim 1 .
25. The brazing sheet according to claim 1 , wherein the interliner is of 1xxx alloy.
26. The brazing sheet according to claim 1 , wherein the interliner is of 7xxx alloy.
27. The brazing sheet according to claim 1 , wherein the interliner comprises 0.8-0.9 wt % Mn and 1.2 to 2.6 wt % Zn.
28. The brazing sheet according to claim 1 , wherein the core comprises 0.65-0.95 wt % Mn and the interlayer has 0.03 wt % Ti.
29. The brazing sheet according to claim 1 ,
wherein the core comprises 0.88-0.95 wt % Mn;
wherein the interliner is made of 3xxx alloy consisting of:
≦0.02 wt % Cu
0.8-0.9 wt % Mn
≦0.01 wt % Mg
1.2-2.6 wt % Zn
0.03 wt % Ti
<0.4 wt % Si
<5 wt % Fe
balance aluminium and unavoidable impurities.