時効硬化したアルミニウム合金板の張出し成形限界

Abstract

The stretch formability of age-hardening aluminum alloys has been studied by the hydraulic bulging test for 2036, 6061, 6009 and 7N01 alloy sheets under various heat treating conditions. In contrast to the deep drawability, the stretch formability of these alloys lowers with the progress of age-hardening. The maximum bulging height is closely correlated to the total elongation and n-value by the tensile test. A decrease in the maximum bulging height is larger for the materials aged at higher temperatures in which the total elongation and n-value are appreciably decreased. In 2036 alloy, the T4 and low temperature aged materials show higher forming limit strains than the annealed material, whereas the highest forming limit strain is obtained for the annealed material of the other tested alloys. Among the tested specimens of these four alloys under various heat treating conditions, the highest stretch formability is obtained for the annealed materials of 6061 and 6009 alloys, to which the as solutionized materials of these two alloys are second. The T4 and low temperature aged materials of 2036, 6061 and 6009 alloys can be stretch-formed to the nearly the same limit strain, which is higher than that of 7N01 alloy.The 7N01 alloy sheet has the lowest stretch formability among the four tested alloys in all respects.