METHOD FOR PRODUCING HIGH STRENGTH AND HIGH FORMABILITY ALUMINUM ALLOY SHEET AND ALUMINUM ALLOY SHEET OBTAINED BY THE SAME PRODUCING METHOD

摘要

PROBLEM TO BE SOLVED: To provide a method for producing an aluminum alloy sheet by which, as for an Al-Mg alloy containing a relatively small amount of Mg of 3.0 to 5.0%, a sheet material having a fine recrystallized grain structure and excellent in strength and formability can be produced without undergoing recrystallization annealing and to provide an aluminum alloy sheet obtainable by the same method. ;SOLUTION: An aluminum alloy sheet containing 3.0 to 5.0% Mg, and the balance Al with impurities is cold-rolled at a draft of ≥70% to form the structure of the matrix of the same aluminum alloy sheet into the unrecrystalled one, and, after that, the aluminum alloy sheet is stretched at 200 to 300°C at a strain rate of ≥1×10-4/sec and a tensile amount of ≥10%. By this producing method, the above unrecrystallized structure is dynamically recrystallized, by which the aluminum alloy sheet having the average crystal grain size of ≤3 μm can be obtained.;COPYRIGHT: (C)2001,JPO