High strength aluminium alloy extrusion

1. An aluminium extrusion having a minimum section thickness and made from an aluminium alloy having, in weight percent, between approximately 1.0 and 1.7 manganese, between approximately 0.5 and 1.1 silicon, less than 0.3 iron, and below approximately 0.01 copper, with the balance being Al and inevitable impurities each less than 0.05 weight % and totaling less than 0.15 weight %, the extrusion being formed with an extrusion ratio less than 125 to retain a fibrous grain structure in which less than 40% of the minimum section thickness is recrystallized, and wherein the fibrous grain structure is centrally located within a wall of the extruded component.

2. An aluminium extrusion as claimed in claim 1 intended for use in corrosion resistant applications, the alloy having at least one additional alloying element selected from a group consisting of: zinc greater than 0.10 and less than 0.30 weight % and titanium greater than 0.10 and less than 0.20 weight %.

3. An aluminium extrusion as claimed in claim 1 , wherein less than 25% of the minimum section thickness is recrystallized.

4. An aluminium extrusion as claimed in claim 1 , wherein the minimum section thickness is larger or equal to 1.0 mm.

5. An aluminium extrusion as claimed in claim 1 , wherein the component has a yield strength higher than 50 MPa, a tensile strength higher than 125 MPa, and an elongation above 15%.

6. An aluminium extrusion as claimed in claim 1 , wherein the extrusion ratio is less than 75.

7. An aluminium extrusion as claimed in claim 1 , wherein the manganese content ranges between approximately 1.4 and 1.6 wt %.

8. An aluminium extrusion as claimed in claim 1 , wherein the silicon content ranges between approximately 0.5 and 0.7 wt %.

9. An aluminium extrusion as claimed in claim 1 , wherein the aluminium alloy is subjected to a single step homogenization.

10. An aluminium extrusion as claimed in claim 1 , wherein the minimum section thickness is larger or equal to 2 mm.

11. An aluminium extrusion as claimed in claim 1 , wherein the wall has surface layers surrounding the fibrous grain structure, with the surface layers having recrystallized grain structures.

12. An aluminium extrusion as claimed in claim 11 , wherein the wall has a thickness defining the minimum section thickness.

13. An aluminium extrusion having a wall having a thickness defining a minimum section thickness and made from an aluminium alloy having, in weight percent, between approximately 1.0 and 1.7 manganese, between approximately 0.5 and 1.1 silicon, less than 0.3 iron, and below approximately 0.01 copper, with the balance being Al and inevitable impurities each less than 0.05 weight % and totaling less than 0.15 weight %, the extrusion being formed with an extrusion ratio less than 125 to achieve a grain structure in which less than 40% of the minimum section thickness is recrystallized, and wherein the wall has a central portion within the thickness having an unrecrystallized grain structure and surface layers surrounding the central portion and having recrystallized grain structures.

14. An aluminium extrusion as claimed in claim 13 , wherein less than 25% of the minimum section thickness is recrystallized.

15. An aluminium extrusion as claimed in claim 13 , wherein the minimum section thickness is larger or equal to 1.0 mm.

16. An aluminium extrusion as claimed in claim 13 , wherein the component has a yield strength higher than 50 MPa, a tensile strength higher than 125 MPa, and an elongation above 15%.

17. An aluminium extrusion as claimed in claim 13 , wherein the manganese content ranges between approximately 1.4 and 1.6 wt %.

18. An aluminium extrusion as claimed in claim 13 , wherein the silicon content ranges between approximately 0.5 and 0.7 wt %.

19. An aluminium extrusion as claimed in claim 13 , wherein the minimum section thickness is larger or equal to 2 mm.