Aluminum alloy extruded material and method of manufacturing the same

Abstract

An aluminum alloy extruded material having chemical composition that includes Cu by 2.5 to 3.3%, Mg by 1.3 to 2.5%, Ni by 0.50 to 1.3%, Fe by 0.50 to 1.5%, Mn by less than 0.50%, Si by 0.15 to 0.40%, Zr by 0.06 to 0.20%, and Ti by less than 0.05% in mass percentage, and the remaining part that includes Al and inevitable impurities. On a cross-section of the aluminum alloy extruded material, a grain diameter of an intermetallic compound is 20μm or less in equivalent circle diameter; density of an intermetallic compound, whose grain diameter is 0.3 to 20μm in equivalent circle diameter, is 5×103 piece/mm2 or more; and, an average grain diameter of sub-crystal grains is 20μm or less in equivalent circle diameter.

1 . An aluminum alloy extruded material, comprising:
 chemical composition that comprises
 Cu by 2.5 to 3.3%, Mg by 1.3 to 2.5%, Ni by 0.50 to 1.3%, Fe by 0.50 to 1.5%, Mn by less than 0.50%, Si by 0.15 to 0.40%, Zr by 0.06 to 0.20%, and Ti by less than 0.05% in mass percentage, and 
 a remaining part that comprises Al and inevitable impurities, 
   wherein, on a cross-section of the aluminum alloy extruded material, a grain diameter of an intermetallic compound is 20 μm or less in equivalent circle diameter; density of an intermetallic compound whose grain diameter is 0.3 to 20 μm in equivalent circle diameter is 5×10 3  piece/mm 2  or more; and, an average grain diameter of sub-crystal grains is 20 μm or less in equivalent circle diameter.   
     
     
         2 . A method of manufacturing the aluminum alloy extruded material according to  claim 1 , the method comprising:
 processing an ingot of an aluminum alloy that comprises the chemical composition with homogenizing treatment at a temperature from 400 to 500° C.;   cooling the ingot from the temperature of the homogenizing treatment to 200° C. or less at an average cooling speed of 0.01° C./s or more;   extruding the ingot at 310 to 450° C.;   processing an intermediate extruded material obtained by the extruding with solution treatment and quenching;   processing the intermediate extruded material with stretch levelling at 2 to 4% strain within 48 hours after the solution treatment and quenching; and,   processing the intermediate extruded material with aging treatment at 160 to 220° C.