Aluminum Alloys and Process for Making Aluminum Alloy Sheet

摘要

An alloy of aluminum containing magnesium, silicon and optionally copper in amounts in percent by weight as shown in the figure, i.e. approximately falling within one of the following ranges: (1) 0.4 <= Mg < 0.8, 0.2 & lt;= Si < 0.5, 0.3 <= Cu <= 3.5; (2) 0.8 <= Mg <= 1.4, 0.2 <= Si < 0 .5, Cu <= 2.5; and (3) 0.4 <= Mg <= 1.0, 0.5 <= Si <= 1.4, Cu <= 2.0. The alloy may also contain at least one additional element selected from Fe in an amount of 0.4 percent by weight or less, Mn in an amount of 0.4 percent by weight or less, Zn in a n amount of 0.3 percent by weight or less and a small amount of at least one other element, such as Cr, Ti, Zr and V. The alloy may be fabricated into sheet material suitable in a belt casting machine by casting the alloy while extracting heat from the alloy at a rate that avoids both shell distortion o f the sheet and excessive surface segregation, at least until said alloy freezes. The alloy may then be subjected to a solution heat treatment, to re - dissolve precipitated particles and to a cooling process at a rate that produces a T4 temper and a potential T8X temper suitable for automotive panels. By such means, panels suitable for automotive use can be produced efficiently and economically.