Patent ID: 6524410
Filing Date: 2003-02-25
Classification: C22C,C22F

Abstract:
A method for producing a lightweight welded structure comprising:a) mixing alloy elements into aluminum with the alloy composition containing 4.2 to 6.5 wt. % Zn, 1.0 to 2.5 wt. % Mg, 0 to 0.70 wt. % Cu, and 0.05 to 1.0 wt. % of at least one grain refining element selected from a group consisting of Zr, Sc, Cr, Mn, Ti, Hf and V, the remainder comprising aluminum, incidental elements and impurities, and casting the alloy into a billet; b) homogenizing said billet at an elevated temperature to provide suitable starting stock for extrusion; c) extruding said billet into tube; d) optionally, drawing said extruded tube into a thinner walled tube with one or more drawing passes; e) solution heat treating said tubular members; f) quenching said tubular members; g) artificial aging said tubular members; h) welding said tubular members together to form a welded structure; i) further aging said welded structure at ambient temperature or greater to effect strengthening of the weldment wherein at least one of the tubular members of the welded structure have a tensile yield strength of at least 60 ksi measured in the longitudinal direction of the tubular member.