Preformable aluminum-alloy rolled sheet adapted for superplastic forming and method for producing the same

摘要

An aluminum-alloy rolled sheet is cold preformed and then superplastically formed by: providing a composition which consists of from 2.0 to 8.0% of Mg, from 0.0001 to 0.01% of Be, and at least one element selected from the group consisting of from 0.3 to 2.5% of Mn, from 0.1 to 0.5% of Cr, from 0.1 to 0.5% of Zr, and from 0.1 to 0.5% of V, less than 0.2% of Fe as impurities, as well as aluminum and unavoidable impurities in balance; providing an unrecrystallized structure formed by annealing at a temperature of from 150 to 240 C. for 0.5 to 12 hours or at a temperature of from 250 to 340 C. for 0 to 5 minutes; providing draft of final cold-rolling amounting to 50% or more; and, providing 7% or more of elongation at normal temperature.