A method for the production of cured sheets of aluminum alloys with high strength and very good corrosion resistance.

摘要

PURPOSE:To produce a hard Al alloy sheet for high-degree forming excellent in corrosion resistance and having superior formability and flatness by applying specific heat treatment to a rolled sheet having a specific composition consisting of Mg, Cu, Mn, Ti, and Al. CONSTITUTION:A molten metal having a composition which consists of, by weight, 4.0-6.0% Mg, 0.05-0.50% Cu, 0.10-1.0% Mn, 0.01-0.05% Ti, and the balance Al with impurities and in which 0.05-0.20% Cr is further added, if necessary, is prepared. The above molten metal is solidified, which is hot-rolled and cold- rolled. The resulting rolled sheet is heated up to 150-300 deg.C at =5 deg.C/sec temp.-rise rate and held at the above temp. for =5min. Then, the above rolled sheet is cooled down to =70 deg.C at =30 deg.C/sec cooling rate. At this time, if necessary, the above rolled sheet can be subjected to the above heat treatment in a tension- applied state after flattened by means of stress straightening at ordinary temp. By this method, the hard Al alloy sheet having mechanical properties sufficient for forming material, also having noble pitting corrosion potential, and reduced in corrosion sensitivity can be obtained.