ALUMINUM ALLOY WITH WORKABILITY OF BENDING AND MANUFACTURING METHOD THEREOF AND HEADREST FRAME FOR VEHICLE PRODUCTED THEREBY

摘要

A high strength aluminum alloy workpiece with improved workability in which cracking is not generated even during bending, a method for manufacturing the aluminum alloy workpiece, and a headrest frame for automobile manufactured by bending the aluminum alloy workpiece are provided. A method for manufacturing a high strength aluminum alloy workpiece with improved workability comprises: a step(S01) of casting an aluminum alloy having a composition comprising 0.1 wt.% or less of Si, 0.2 wt.% or less of Fe, 0.07 to 0.15 wt.% of Cu, 0.1 to 0.15 wt.% of Mn, 1.2 to 1.3 wt.% of Mg, 0.07 to 0.12 wt.% of Cr, 5.7 to 5.9 wt.% of Zn, 0.015 to 0.04 wt.% of Ti and 0.15 wt.% or less of inevitable impurities into billets; a step(S02) of extruding the cast billets in a predetermined shape to form an extrudate; a T6 heat treatment step of subjecting the extrudate to solid solution treatment and subjecting the solid solution-treated extrudate to artificial age hardening; and an over-aging step(S06) of subjecting the extrudate to artificial age hardening at a temperature of 170 to 180 deg.C for 1 to 3 hours. The T6 heat treatment step includes a step(S03) of subjecting the extrudate to solid solution treatment, a step(S04) of properly drawing the solid solution-treated extrudate according to the shape of a predetermined product, and a step(S05) of subjecting the drawn extrudate to artificial age hardening.