Aluminum alloy plastic worked article, method for manufacturing the same, and automobile component

Abstract

To provide an aluminum alloy plastic worked article in which an aluminum texture state having preferable corrosion resistance and preferable mechanical characteristics in terms of, for example, the strength, the proof stress, and the elongation is formed. In an aluminum alloy plastic worked article including a plastic worked portion which is formed of a thinned portion 22 formed by plastic working and rib portions 21 formed at two ends of this thinned portion 22 and which has an approximately H-shaped or U-shaped cross-section, the plastic worked portion is a plastic worked portion 2 having strain portions 23 in each of which an equivalent strain of up to 4.0 mm/mm generated by plastic working is present, and the strain portions 23 are each located in the vicinity of the surface of the plastic worked portion 2 at a boundary between the thinned portion 22 and each of the rib portions 21 and are each formed of a non-recrystalline texture N of aluminum (atomic symbol: Al) which is not recrystallized or are each formed of the non-recrystalline texture N and a fine crystalline texture M which is recrystallized but has a crystal grain of 500 μm or less.

1 . An aluminum alloy plastic worked article characterized by comprising: a plastic worked portion which is formed of a thinned portion formed by plastic working and rib portions formed at two ends of this thinned portion and which has an approximately H-shaped or U-shaped cross section,
 wherein the plastic worked portion has strain portions in each of which an equivalent strain of up to 4.0 mm/mm generated by the plastic working is present,   the strain portions are each located in the vicinity of the surface of the plastic worked portion at a boundary between the thinned portion and each of the rib portions, and   the strain portions are each formed of a non-recrystalline texture of aluminum (atomic symbol: Al) which is not recrystallized or are each formed of the non-recrystalline texture and a fine crystalline texture of the aluminum which is recrystallized but has a crystal grain of 500 μm or less.   
     
     
         2 . The aluminum alloy plastic worked article according to  claim 1 , characterized in that
 the composition contains 0.15 to 0.5 percent by mass of copper (atomic symbol: Cu), 0.8 to 1.15 percent by mass of magnesium (atomic symbol: Mg), 0.95 to 1.15 percent by mass of silicon (atomic symbol: Si), 0.4 to 0.6 percent by mass of manganese (atomic symbol: Mn), 0.2 to 0.3 percent by mass of iron (atomic symbol: Fe), 0.11 to 0.19 percent by mass of chromium (atomic symbol: Cr), 0.25 percent by mass or less of zinc (atomic symbol: Zn), 0.05 percent by mass or less of zirconium (atomic symbol: Zr), 0.012 to 0.035 percent by mass of titanium (atomic symbol: Ti), 0.0001 to 0.03 percent by mass of boron (atomic symbol: B), and the balance including aluminum and inevitable impurities, and   when a width direction length of the rib portion is represented by x (cm), a height direction length of the thinned portion is represented by y (cm), and a height direction length of the rib portion is represented by z (cm), the content (percent by mass) of the manganese satisfies the following equation [Eq. 1]
   Manganese (percent by mass)=0.4α{ z /( x+y )+0.25}  [Eq. 1]
 
   where z/(x+y)≧0.65 and α=0.8 to 0.9 hold.   
     
     
         3 . The aluminum alloy plastic worked article according to  claim 1 , characterized by being an automobile component. 
     
     
         4 . A method for manufacturing the aluminum alloy plastic worked article according to  claim 1 , characterized in that
 melting/casting is performed, and after a homogenizing treatment and plastic working are performed on a cast product obtained by the melting/casting, a solution treatment, a water quenching treatment, and an artificial age hardening treatment are performed.   
     
     
         5 . The method for manufacturing the aluminum alloy plastic worked article according to  claim 4 , characterized in that
 the artificial age hardening treatment is performed at an aging treatment temperature of 170° C. to 210° C. for an aging treatment time of 0.5 to 18 hours.   
     
     
         6 . The method for manufacturing the aluminum alloy plastic worked article according to  claim 4 , characterized in that
 the solution treatment is performed at a solution treatment temperature of 520° C. to 560° C., and   the water quenching treatment is performed at a water quenching treatment temperature of 70° C. or less.   
     
     
         7 . The method for manufacturing the aluminum alloy plastic worked article according to  claim 4 , characterized in that
 the plastic working is performed by at least one type selected from extruding, forging, and rolling.   
     
     
         8 . An automobile component characterized by being obtained by the method for manufacturing the aluminum alloy plastic worked article according to  claim 4 .