| 摘要 |
A substantially unrecrystallized extrusion comprising about 3.6 to about 4.2 wt. % copper, about 1.0 to about 1.6 wt. % magnesium, about 0.3 to about 0.8 wt. % manganese, about 0.05 to 0.25% zirconium, the balance substantially aluminum, incidental elements and impurities. The extrusion has a longitudinal yield strength of at least about 50 ksi and a longitudinal tensile ultimate strength of at least about 70 ksi. On a preferred basis, the extrusions of this invention include very low levels of both iron and silicon, typically on the order of less than 0.1 wt. % each, and more preferably about 0.05 wt. % or less iron and about 0.03 wt. % or less silicon.
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