Clad metal sheet and heat exchanger tubing etc. made therefrom
View Patent ↗The exemplary embodiments relate to a multilayer aluminum alloy sheet material suitable for fabrication into coolant-conveying tubes, headers and the like used for heat exchangers, and to the tubes and headers, etc., fabricated from the sheet. The multi-layer metal sheet has a core layer of aluminum alloy having first and second sides. The first side has an interlayer made of a Zn-containing aluminum alloy positioned between a Zn-containing outer layer and the core layer. The alloy of the outer layer is more electronegative than the alloy of the interlayer. The alloy of the interlayer is preferably more electronegative than the alloy of the core layer. The first side clad in this way is the side intended for exposure to the coolant, and provides good resistance to corrosion and erosion.
1. A multi-layer metal sheet comprising a core layer of aluminum alloy having first and second sides, wherein said first side of said core layer has an interlayer made of a Zn-containing aluminum alloy positioned between a Zn-containing outer layer and the core layer, the alloy of the outer layer being more electronegative than the alloy of the interlayer, and the alloy of the core being less electronegative than the interlayer, and wherein said interlayer is made of an alloy which comprises about 0.9 to 2.0 wt % Mn, about 0.002 to 0.7 wt % Cu, up to 0.4 wt % Fe, 0.5 to 2.0 wt % Si, up to 7.0 wt % Zn, and the balance aluminum and unavoidable impurities, if any; and said outer layer is made of an Al—Zn alloy which contains a minimum of 3 wt % Zn.
2. The sheet of claim 1 , wherein the alloy of the outer layer is more electronegative than the alloy of the interlayer by at least 50 mV.
3. The sheet of claim 1 , wherein said core layer is made of an alloy which comprises about 0.5 to 2.0 wt % Mn, about 0.1 to 1.0 wt % Cu, up to 0.4 wt % Fe, up to 0.25 wt % Si, and up to 0.8 wt % Mg, with the balance aluminum and unavoidable impurities, if any.
4. The sheet of claim 1 , wherein the alloy of the outer layer contains 3 to 7 wt % Zn.
5. The sheet of claim 1 , having a coating made of a brazing alloy on said second side.
6. The sheet of claim 5 , wherein said coating on said second side comprises an aluminum alloy of the AA4000 series.
7. The sheet of claim 1 , wherein said alloy of said interlayer comprises aluminum and the following elements in the amounts shown in wt %:
Element
Amounts
Cu
≦0.010
Fe
0.15-0.25
Mg
≦0.05
Mn
1.5-2.0
Si
0.90-1.00
Ti
0.005-0.020
V
≦0.010
Zn
1.0-5.0
Zr
≦0.010
Cr
≦0.30.
8. The sheet of claim 1 , wherein said alloy of said interlayer comprises aluminum and the following elements in the amounts shown in wt %:
Element
Amounts
Cu
≦0.010
Fe
0.15-0.25
Mg
≦0.05
Mn
0.97-1.03
Si
0.90-1.00
Ti
0.005-0.020
V
≦0.010
Zn
1.0-5.0
Zr
≦0.010
Cr
≦0.30.
9. The sheet of claim 1 , wherein said core layer is made of an alloy comprising aluminum and the following elements in amounts shown in wt %:
Element
Amounts
Cu
0.5-1.0
Fe
≦0.4
Mg
≦0.8
Mn
0.7-1.9
Si
≦0.25
Ti
≦0.1
Zn
≦0.1
Cr
≦0.03.
10. The sheet of claim 1 , wherein said core layer is made of an alloy comprising aluminum and the following elements in amounts shown in wt %:
Element
Amounts
Cu
0.5-0.65
Fe
0.14-0.24
Mg
≦0.01
Mn
1.45-1.54
Si
0.03-0.09
Ti
0.005-0.030
Zn
≦0.04
Cr
≦0.01.
11. The sheet of claim 1 , wherein the alloy of the interlayer is more electronegative than the alloy of the core by at least 50 mV.
12. A tube made of the clad metal sheet of claim 1 , wherein said Zn-containing outer layer forms an internal surface of the tube.
13. A radiator header made of the clad metal of claim 1 , wherein said Zn-containing outer layer forms an internal surface of the header.