EXTRUDED MATERIAL OF ALUMINUM ALLOY FOR STRUCTURAL MEMBERS OF AUTOMOBILE BODY AND METHOD OF MANUFACTRUING THE SAME

摘要

There is disclosed an aluminum alloy extruded material for structural members of automotive bodies, which is composed of an aluminum alloy containing more than 2.6 wt% but 4.0 wt% or less of Si and more than 0.3 wt% but 1.5 wt% or less of Mg, further, (i) containing Mn, Zn, Cu, and Fe each in a given amount, or (ii) containing Zn, Cu, and Fe each in a given amount and containing at least one selected from among Mn, Cr, Zr, and V in a given amount, and the balance being made of Al and unavoidable impurities, which material has a given conductivity and a given melting start temperature. There is also disclosed a method for producing the extruded material, in which after an aluminum alloy ingot of the above composition is subjected to a homogenizing treatment at given conditions, it is cooled, heated again, and subjected to hot extrusion at given conditions. The extruded material is excellent in spot weldability and surface treatment property, such as the chemical conversion property and degreasing property, and it has high mechanical strength and ductility, and is excellent in impact absorbability and/or bendability.