PROCESS FOR MAKING ALUMINUM ALLOY SHEET HAVING EXCELLENT BENDABILITY

摘要

A process is described for producing an aluminum alloy sheet having excellent bendability for use in forming panels for automobiles. An aluminum alloy containing 0.50 to 0.75 by weight Mg, 0.7 to 0.85% by weight Si, 0.1 to 0.3% by weight Fe, 0.15 to 0.35% by weight Mn, and the balance Al and incidental impurities, is used and is semi-continuously cast into ingot. The cast alloy ingot is subjected to hot rolling and cold rolling, followed by solution heat treatment of the formed sheet. The heat treated sheet is quenched to a temperature of about 60 - 120°C and the sheet is then coiled. This coil is then pre-aged by slowly cooling the coil from an initial temperature of about 60 - 120°C to room temperature at a cooling rate of less than 10°C/hr. Another aluminum alloy containing 0.0 0.4 % by weightCu, 0.3 0.6 by weight Mg, 0.45 0.7 % by weight Si, 0.0 0.6 % by weight Mn, 0.0 0.4 % by weight Fe, up to 0.06 % by weight Ti, and the balance A1 and incidental impurities, is used and is semi-continuously cast into ingot. The cast alloy ingot is subjected to hot rolling and cold rolling, followed by solution heat treatment of the formed sheet. The heat treated sheet is quenched to a temperature of about 60 120<0>C and the sheet is then coiled and cooled to room temperature.