Creep resistant aluminium alloy for multilayer tubes
The invention relates to an aluminum alloy product containing, in wt. %: Si 0.2 to 1.4; Fe+Mn 1.1 to 1.8; Cu 0.15 to 0.5; Mg<0.2; Ti<0.2; Zn<1.5; impurities<0.05 each, <0.2 total, balance aluminum. This aluminum alloy product has high resistance to internal pressure when used as core layer for welded multilayer tubing. The invention relates also to a method of manufacturing such alloy product, and the use of such alloy in welded multilayer tubes.
1. Multilayer tube having a tube wall comprising a core layer made solely from a rolled aluminium alloy product devoid of any further metallic layer(s), an inner layer made of plastic and an outer layer made of plastic, and wherein the core layer is an aluminium alloy consisting of, in wt. %:
Si
0.2 to 1.4
Fe + Mn
1.1 to 1.8
Cu
0.15 to 0.5
Mg
<0.20
Ti
<0.20
Zn
<1.5,
Pb + Bi
<0.05%.
and other impurities or incidental elements each <0.05, total <0.2, and the balance being aluminium.
2. Multilayer tube having a tube wall comprising a core layer made solely from a rolled aluminium alloy product devoid of any further metallic layer(s), an inner layer made of plastic and an outer layer made of plastic, and wherein the core layer is an aluminium alloy consisting of, in wt. %:
Si
0.2 to 1.4
Fe + Mn
1.1 to 1.8
Cu
0.15 to 0.5
Mg
<0.20
Ti
<0.20
Zn
<1.5,
and other impurities or incidental elements each <0.05, total <0.2, and the balance being aluminium.
3. Multilayer tube according to claim 1 , wherein the Si-content is in a range of 0.85 to 1.4%.
4. Multilayer tube according to claim 1 , wherein the Fe-content in the core layer is in a range of 0.20 to 0.8%, and Mn is in the range of 0.90 to 1.15%.
5. Multilayer tube according to claim 1 , wherein the Mn-content in the core layer is in a range of 0.20 to 0.50%, and Fe is in the range of 0.90 to 1.30%.
6. Multilayer tube according to claim 1 , wherein the Cu-content in the core layer is in a range of 0.15 to 0.30%.
7. Multilayer tube according to claim 1 , wherein the Mg-content in the core layer is in a range of 0.05 to 0.10%.
8. Multilayer tube according to claim 1 , wherein the Zn-content in the core layer is in a range of at most 1.0%.
9. Multilayer tube according to claim 1 , wherein the Ti-content in the core layer is in a range of 0.11 to less than 0.20%.
10. Multilayer tube according to claim 1 , wherein the core layer has a gauge in a range of 0.1 to 1.0 mm.
11. Multilayer tube according to claim 1 , wherein the tube has a resistance against sustained pressure without failure of more than 100 hours at 95° C. at a 30 bar internal pressure in accordance with ASTM-F1281 creep test.
12. Multilayer tube according to claim 1 , wherein the multilayer tube is a sanitary pipe or heating pipe in a building.
13. Multilayer tube according to claim 1 , wherein the core layer is bent into the shape of a tube and welded at its seam.
14. Multilayer tube according to claim 1 , wherein the Si-content is in a range of 0.85 to 1.2%.
15. Multilayer tube according to claim 1 , wherein the Fe-content in the core layer is in a range of 0.30 to 0.45%, and Mn is in the range of 0.90 to 1.15%.
16. Multilayer tube according to claim 1 , wherein the Mn-content in the core layer is in a range of 0.30 to 0.50%, and Fe is in the range of 0.90 to 1.30%.
17. Multilayer tube according to claim 1 , wherein the Cu-content in the core layer is in a range of 0.20 to 0.30%.
18. Multilayer tube according to claim 1 , wherein the Zn-content in the core layer is in a range of at most 0.5%.
19. Multilayer tube according to claim 1 , wherein the Zn-content in the core layer is in a range of at most 0.20%.
20. Multilayer tube according to claim 1 , wherein the Ti-content in the core layer is in a range of 0.11 to 0.16%.
21. Multilayer tube according to claim 1 , wherein the core layer has a gauge in a range of 0.15 to 0.6 mm.
22. Multilayer tube according to claim 1 , wherein the Zr-content in the core layer, if present, is at an impurity level of <0.05%.
23. Multilayer tube according to claim 1 , wherein the Zr-content in the core layer, if present, is at an impurity level of <0.02%.
24. Multilayer tube according to claim 1 , wherein the core layer is substantially free of Zr.
25. Multilayer tube according to claim 1 , wherein the core layer is substantially free of Cr.