Impact absorbing material

Abstract

An impact absorbing material formed by: casting an aluminum alloy into a billet, the aluminum alloy including 5.6 to 6.6 wt % of zinc, 0.75 to 1.10 wt % of magnesium, 0.10 to 0.25 wt % of copper, 0.05 to 0.20 wt % of manganese, 0.03 to 0.15 wt % of chromium, 0.10 to 0.25 wt % of zirconium, 0.02 to 0.10 wt % of silicon, 0.05 to 0.17 wt % of iron, and the balance being aluminum and unavoidable impurities; extruding the billet to obtain an extruded shape having a hollow cross-section; and subjecting the extruded shape to artificial aging so that 0.2% proof stress is in a range of 340 to 385 MPa.

1 . An impact absorbing material formed by: 
 casting an aluminum alloy into a billet, the aluminum alloy including 5.6 to 6.6 wt % of zinc, 0.75 to 1.10 wt % of magnesium, 0.10 to 0.25 wt % of copper, 0.05 to 0.20 wt % of manganese, 0.03 to 0.15 wt % of chromium, 0.10 to 0.25 wt % of zirconium, 0.02 to 0.10 wt % of silicon, 0.05 to 0.17 wt % of iron, and the balance being aluminum and unavoidable impurities;    extruding the billet to obtain an extruded shape having a hollow cross-section; and    subjecting the extruded shape to artificial aging so that 0.2% proof stress is in a range of 340 to 385 MPa.    
     
     
         2 . The impact absorbing material as defined in  claim 1 , 
 wherein the temperature of the extruded shape in extrusion is controlled to be in a range of 500 to 540° C. to improve the stress corrosion cracking resistance.    
     
     
         3 . An automobile impact absorbing material comprising the impact absorbing material as defined in  claim 1 .  
     
     
         4 . An automobile impact absorbing material comprising the impact absorbing material as defined in  claim 2.