An extruded material from an aluminum alloy for the structural parts of an automobile and process for their preparation

摘要

An extruded material of an aluminum ally for structural members of an automobile body, comprising over 2,6 wt. % and not more than 4 wt. % of Si, over 0,3 wt. % and not more than 1,5 wt. % of Mg, (i) a predetermined amount of Mn, Zn, Cu and Fe, or (ii) a predetermined amount of Zn, Cu and Fe and a predetermined amount of at least one kind of substance selected from Mn, Cr, Zr and V, and Al and unavoidable impurities for the remainder, and having predetermined conductivity and melting starting temperature; and a method of manufacturing the same extruded material, comprising subjecting an aluminum alloy ingot of the above-mentioned composition, to homogeneization under predetermined conditions, cooling, reheating, and then hot extrusion under predetermined condition, the extruded material being excellent in spot weldability, surface treatment characteristics, such as formation treatment characteristics and degreasing characteristics, strength, ductility, and impact absorptivity and/or bendability.