ALUMINUM ALLOY SHEET HAVING EXCELLENT PRESS FORMABILITY AND SHAPE FIXABILITY, AND METHOD FOR MANUFACTURING SAME.

摘要

A JIS5000-type aluminum alloy sheet having excellent press formability and shape fixability, and having high strength suitable for an automobile body sheet, and a method for manufacturing the same are provided. This aluminum alloy sheet has: a component composition containing 3.4-5.5 mass% of Mg, 0.05-0.25 mass% of Fe, and 0.005-0.10 mass% of Ti, the content of Si as an impurity being restricted to less than 0.20 mass%, and the remainder essentially comprising Al and unavoidable impurities; a metallographic structure in which the average crystal particle diameter is less than 15 µm and the number of second-phase particles having an equivalent circle diameter of 3 µm or greater is less than 300/mm2; and a tensile strength of at least 240 MPa, a yield strength of less than 130 MPa, an elongation of at least 30%, and a plane strain fracture limit of at least 0.20 at a strain rate of 20/sec. A manufacturing method in which conditions of each step are specified in order to manufacture the abovementioned aluminum alloy sheet.