A method for producing an aluminum alloy case material for a sealed prismatic battery excellent in formability and creep resistance, a sealed prismatic battery case and a sealed prismatic battery.

摘要

PROBLEM TO BE SOLVED: To provide the case material having moderate strength without impairing case formability and without causing any deformation or breakage due to increase in internal pressure by subjecting an Al alloy ingot having a specific composition consisting of Mn, Si, Fe, and Al to hot rolling, to cold rolling, and to prescribed annealing treatment and providing specific electric conductivity. SOLUTION: An Al alloy ingot, which has a composition consisting of, by weight, 0.5-1.5% Mn, 0.1-0.5% Si, 0.3-1.0% Fe, and the balance Al with inevitable impurities and further optionally containing =0.5% Cu, is hot-rolled, cold-rolled, and subjected to annealing treatment consisting of holding at =450 deg.C and cooling down to 200 deg.C at =1 deg.C/sec cooling rate. Further, if necessary, cold rolling and aging treatment consisting of holding at 100-250 deg.C are applied. In this annealing treatment, Mn is allowed to enter into solid solution until electric conductivity to be an index to the amount of entering into solid solution becomes =45 IACS%. By this method, the Al-alloy case material for enclosed-type rectangular cell, excellent in case formability and creep resistance and having high strength enough to withstand the increase in internal pressure at the time of charging, can be obtained.