Extruded structural component for a motor vehicle and method for its manufacture

An extruded structural component for a motor vehicle, the extruded structural component comprising:

• an aluminum alloy, wherein the aluminum alloy has the following composition in addition to Al and unavoidable impurities:
• 4.50 to 5.5 wt % Zn;
• 0.50 to 1.7 wt % Mg;
• 0.10 to 0.20 wt % Zr;
• 0.12 to 0.35 wt % Cu;
• 0.02 to 0.16 wt % Si;
• 0.00 to 0.30 wt % Fe;
• as well as 0.00 to 0.10 wt % Mn and less than 0.05 wt % Cr and/or Ti,
• wherein the Zn and the Mg are present in a weight ratio of 5.0 to 5.8,
• the extruded structural component is formed in a W temper after extrusion and has one of the temper conditions T7 or T7x according to EN 515,
• the extruded structural component is hollow and has an elasticity limit Rp0.2>250 MPa, and
• the extruded structural component has recrystallized outer layers, each of which has a thickness corresponding to less than 15% of a wall thickness of the extruded structural component.

A method of manufacturing a structural component of a motor vehicle, the method comprising:

• extruding an aluminum alloy into a hollow extruded profile, wherein the aluminum alloy material, in addition to Al and unavoidable impurities, has the following composition:
• 4.50 to 5.5 wt % Zn;
• 0.50 to 1.7 wt % Mg;
• 0.10 to 0.20 wt % Zr;
• 0.12 to 0.35 wt % Cu;
• 0.02 to 0.16 wt % Si;
• 0.00 to 0.30 wt % Fe;
• as well as 0.00 to 0.10 wt % Mn and less than 0.05 wt % Cr and/or Ti,
• wherein the Zn and the Mg are present in a weight ratio of 5.0 to 5.8,
• solution annealing the hollow extruded profile below at a recrystallization temperature at 450° C. to 560° C.;
• quenching the solution-annealed extruded profile, at a cooling rate of 5 to 100° C./min down to a temperature of 200° C.;
• forming the solution-annealed and quenched extruded profile into a structural component in a W-temper condition within 2 hours after said extruding;
• and
• artificial aging of the structural component so that the structural component has one of the temper conditions T7 or T7x according to EN 515.