Patent ID: 7048816
Filing Date: 2006-05-23
Classification: C22C,C22F

Abstract:
1. A method of making sheet material of a magnesium containing aluminum alloy for sheet metal forming, said method comprising: continuously casting a composition consisting essentially, by weight, of 3.5 to 5.5% magnesium, 0.4 to 1.6% manganese, 0 to 0.5% chromium, 0.2 to 2.0% copper and aluminum to form a cast slab with an as-cast gage of about 5 to 35 millimeters; hot rolling said cast slab through at least one hot roller stand to form a hot rolled strip that emerges from said rolling at a temperature in the range of 200° C. to 350° C. and having experienced a thickness reduction from the cast slab of 30 to 80% with a rolled strip thickness of about 3 to 12 millimeters; immediately coiling said hot rolled strip; annealing the coiled strip at 450° C. to 560° C. for 3 to 30 hours to produce a microstructure with dispersed intermetallic particles; cold rolling said annealed strip through at least one cold rolling stage, without intermediate anneal, to effect a reduction of at least 50% in the thickness of the hot rolled strip and to yield said sheet material; and thereafter heating said cold rolled sheet material to recrystallize it to a microstructure characterized by grains no larger than about 10 micrometers.