PROCESS FOR PREPARING AN ALUMINUM ALLOY SHEET WITH IMPROVED BENDABILITY AND ALUMINUM ALLOY SHEET PRODUCED THEREFROM

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 is used containing 0.5-0.75% by weight Mg, 0.7-0.85% by weight Si, 0.15-0.35% by weight Mn and 0.1-0.3% by weight Fe and the remainder Al and incidental impurities. The alloy is formed into ingot by semi-continuous casting and the cast alloy ingot is subjected to hot rolling and cold rolling, followed by solution heat treatment of the formed sheet. The sheet material is pre-aged by rapidly cooling from an initial pre-aging temperature of at least 80° C. to room temperature at a cooling rate of more than 5° C./hour.