Aluminum alloys with high strength and cosmetic appeal

Abstract

The disclosure provides aluminum alloys having varying ranges of alloying elements and properties.

1 . An aluminum alloy comprising:
 3.4 to 5.5 wt % Zn;   1.3 to 2.1 wt % Mg;   at least 0.07 wt % Cu;   no greater than 0.08 wt % Zr; and   0.04 to 0.20 wt % Fe;   no greater than 0.05 wt % Ti;   wherein the balance is aluminum and incidental impurities.   
     
     
         2 . The aluminum alloy of  claim 1 , comprising:
 no greater than 0.05 wt % Si;   no greater than 0.05 wt % Mn;   no greater than 0.05 wt % Cr;   no greater than 0.05 wt % Ga;   no greater than 0.05 wt % Sn;   no greater than 0.05 wt % V;   no greater than 0.05 wt % B;   no greater than 0.05 wt % Li;   no greater than 0.05 wt % Cd;   no greater than 0.05 wt % Pb;   no greater than 0.05 wt % Ni;   no greater than 0.05 wt % P;   no greater than 0.05 wt % Na;   no greater than 0.05 wt % Ca;   no greater than 0.03 wt % total of Mn and Cr;   no greater than 0.02 wt % of any one additional element; and   no greater than 0.10 wt % total of additional elements.   
     
     
         3 . The aluminum alloy according to  claim 1 , comprising at least 0.24 wt % Cu. 
     
     
         4 . The aluminum alloy according to  claim 1 , comprising at least 0.28 wt % Cu. 
     
     
         5 . The aluminum alloy according to  claim 1 , comprising 4.5-5.5 wt % Zn and 1.5-2.1 wt % Mg. 
     
     
         6 . The aluminum alloy according to  claim 1 , comprising 4.0-4.8 wt % Zn and 1.2-1.8 wt % Mg. 
     
     
         7 . The aluminum alloy according to  claim 1 , wherein the alloy having a wt % ratio of Zn to Mg from 1.8-3.5. 
     
     
         8 . The aluminum alloy according to  claim 1 , wherein the alloy is tempered under a T6, A79, or A76 condition. 
     
     
         9 . The aluminum alloy according to  claim 1 , wherein the alloy is tempered under an A78 or an A79 condition. 
     
     
         10 . The aluminum alloy according to  claim 1 , wherein the alloy has a yield strength of at least 370 MPa. 
     
     
         11 . The aluminum alloy according to  claim 1 , wherein the alloy has less than 50% failure rate at 1.5 hours in an immersion ASTM G30 U-bend test in a 15% NaCl solution at 85° C. 
     
     
         12 . The aluminum alloy according to  claim 1 , wherein the alloy has less than 50% failure rate in a heat soak ASTM G30 U-bend test at 90% relative humidity (RH) at 65° C. at 50 hours. 
     
     
         13 . A method for producing an aluminum alloy, the method comprising:
 forming a melt that comprises:
 3.4 to 5.5 wt % Zn; 
 1.3 to 2.1 wt % Mg; 
 at least 0.07 wt % Cu; 
 no greater than 0.08 wt % Zr; 
 0.04 to 0.20 wt % Fe; 
 wherein the balance is aluminum and incidental impurities; 
   cooling the melt to room temperature to from a cooled melt;   homogenizing the cooled melt by heating to a first elevated temperature to form a homogenized alloy;   hot-working the homogenized alloy to form a hot-worked alloy;   solution-treating the hot-worked alloy at a second elevated temperature to form a solution treated alloy; and   tempering the solution treated alloy at a third elevated temperature for a period of time to produce the aluminum alloy.   
     
     
         14 . The method of  claim 13 , wherein the melt comprises:
 no greater than 0.05 wt % Si;   no greater than 0.05 wt % Mn;   no greater than 0.05 wt % Cr;   no greater than 0.05 wt % Ti;   no greater than 0.05 wt % Ga;   no greater than 0.05 wt % Sn;   no greater than 0.05 wt % V;   no greater than 0.05 wt % B;   no greater than 0.05 wt % Li;   no greater than 0.05 wt % Cd;   no greater than 0.05 wt % Pb;   no greater than 0.05 wt % Ni;   no greater than 0.05 wt % P;   no greater than 0.05 wt % Na;   no greater than 0.05 wt % Ca;   no greater than 0.03 wt % total of Mn and Cr;   no greater than 0.02 wt % of any one additional element; and   no greater than 0.10 wt % total of additional elements.   
     
     
         15 . The method according to  claim 13 , comprising at least 0.28 wt % Cu. 
     
     
         16 . The method according to  claim 13 , wherein the tempering is under a T6, A79, or A76 condition. 
     
     
         17 . The method according to  claim 13 , wherein the tempering is under an A78 or an A79 condition. 
     
     
         18 . The method according to  claim 13 , wherein the alloy has a yield strength of at least 370 MPa. 
     
     
         19 . The method according to  claim 13 , wherein the alloy has less than 50% failure rate at 1.5 hours in an immersion ASTM G30 U-bend test in a 15% NaCl solution at 85° C. 
     
     
         20 . The method according to  claim 13 , wherein the alloy has less than 50% failure rate in a heat soak ASTM G30 U-bend test at 90% relative humidity (RH) at 65° C. at 50 hours. 
     
     
         21 . An article comprising an alloy comprising:
 3.4 to 5.5 wt % Zn;   1.3 to 2.1 wt % Mg;   at least 0.07 wt % Cu;   no greater than 0.08 wt % Zr; and   0.04 to 0.20 wt % Fe;   wherein the balance is aluminum and incidental impurities.