| 主权项 |
1. A method for producing a sheet of thickness 0.5 to 3.3 mm of essentially unrecrystallized structure made of an aluminum-based alloy said method comprising, successively
a) a molten metal bath is prepared comprising
2.6 to 3.4% by weight of Cu,0.5 to 1.1% by weight of Li,0.1 to 0.4% by weight of Ag,0.2 to 0.8% by weight of Mg,0.11 to 0.20% by weight of Zr,0.01 to 0.15% by weight of Ti, optionally at least one element chosen among Mn, V, Cr, Sc, and Hf, the quantity of element, if chosen, being from 0.01 to 0.8% by weight for Mn, 0.05 to 0.2% by weight for V, 0.05 to 0.3% by weight for Cr, 0.02 to 0.3% by weight for Sc, 0.05 to 0.5% by weight for Hf, a quantity of Zn less than 0.6% by weight, a quantity of Fe and Si less than or equal to 0.1% by weight each, and inevitable impurities with a content less than or equal to 0.05% by weight each and 0.15% by weight in total, b) a slab is cast from said molten metal bath c) said slab is homogenized at a temperature between 450° C. and 515° C.; d) said slab is hot rolled into a plate of thickness between 4 and 12 mm; e) said plate is cold rolled into a sheet of final thickness between 0.5 and 3.3 mm, the reduction in thickness by cold rolling being between 1 and 3.5 mm; f) heat treatment is performed during which the sheet reaches a temperature between 300° C. and 450° C. for at least thirty minutes; g) said sheet undergoes solution heat treatment at a temperature between 450° C. and 515° C. and quenched; h) said sheet undergoes controlled stretching with a permanent deformation of 0.5 to 5%, cold working after solution heat treatment being less than 15%; i) aging is performed at a temperature between 130° C. and 170° C. and optionally between 150° C. and 160° C. for 5 to 100 hours and preferably for 10 to 40 hours. |
