Extruded hollow aluminum alloy panel and method for producing the same

An extruded hollow aluminum alloy panel for automobiles, the panel comprising:

• two plates;
• a first rib joining the plates, the first rib extending perpendicular to the plates and provided adjacent one end of the plates;
• a plurality of second ribs joining the plates, the second ribs provided at a side of the first rib which is opposite the one end of the plates, whereby the plates each have a portion that extends from said first rib to one of said second ribs which is closest to said first rib,
• the panel including an open segment and a closed segment that are integrally formed by extrusion so as to extend in an extrusion direction, the open segment being configured as a guide rail, the closed segment having a plurality of closed spaces defined between the plates by the first and second ribs in a cross section perpendicular to the extrusion direction, the open segment having an open space in the cross section,
• wherein the open segment includes the first rib, protruding portions protruding from the two plates to the outside of the rib in the width direction, and extended portions extended from the outer ends of the protruding portions to the inside of the plates, the extended portions defining an opening extending in the extrusion direction to form the open space, and
• wherein the open segment and said portion of both of said plates that extends from said first rib to said one of said second ribs which is closest to said first rib are constructed to have a higher strength than the strength of a remainder of the closed segment.