Thick wrought 7xxx aluminum alloys, and methods for making the same

Abstract

Improved wrought 7xxx aluminum alloy products are disclosed. The improved wrought 7xxx aluminum alloy products generally include 6.0-10.0 wt. % Zn, 1.4-2.2 wt. % Mg, 1.3-2.5 wt. % Cu and 0.080-0.250 wt. % Cr. The improved wrought 7xxx aluminum alloy products generally have a thickness of from 3.0 inches to 12 inches, and realize an improved combination of properties, such an improved combination of crack deviation resistance, strength, fracture toughness and corrosion resistance.

What is claimed is: 
     
         1 . A wrought 7085 aluminum alloy product having a thickness of 3.0 to 12.0 inches and having 0.080-0.250 wt. % Cr, optionally with 0.07-0.15 wt. % Zr and/or 0.15-0.50 wt. % Mn. 
     
     
         2 . The wrought 7085 aluminum alloy product of  claim 1 , wherein the wrought aluminum alloy product includes a sufficient amount of the Cr, optionally with the Zr and/or the Mn, to achieve at least a 5% increase in K max-dev  as compared to an equivalent 7xxx aluminum alloy product having not greater than 0.01 wt. % Cr and not greater than 0.02 wt. % Mn, at equivalent strength. 
     
     
         3 . The wrought 7085 aluminum alloy product of  claim 1 , wherein the wrought aluminum alloy product includes a sufficient amount of the Cr, optionally with the Zr and/or the Mn, to achieve at least a 18% increase in K max-dev  as compared to an equivalent 7xxx aluminum alloy product having not greater than 0.01 wt. % Cr and not greater than 0.02 wt. % Mn, at equivalent strength. 
     
     
         3 . The wrought 7085 aluminum alloy product of  claim 3 , wherein the wrought aluminum alloy product achieves at least equivalent L-T plane strain K IC  fracture toughness as compared to an equivalent 7xxx aluminum alloy product having not greater than 0.01 wt. % Cr and not greater than 0.02 wt. % Mn. 
     
     
         4 . The wrought 7085 aluminum alloy product of  claim 1 , wherein the wrought aluminum alloy product contains an amount of chromium such that Cr (min) ≦Cr≦Cr (max) , wherein Cr (min)= 0.251−0.082(Mg), and wherein Cr (max) =0.351-0.082(Mg). 
     
     
         5 . The wrought 7085 aluminum alloy product of  claim 1 , wherein the wrought aluminum alloy product is essentially free of zirconium. 
     
     
         6 . The wrought 7085 aluminum alloy product of  claim 1 , wherein the wrought aluminum alloy products include 0.15-0.50 wt. % Mn. 
     
     
         7 . The wrought 7xxx aluminum alloy product of  claim 6 , wherein the wrought aluminum alloy products include 0.07-0.15 wt. % Zr. 
     
     
         8 . The wrought 7085 aluminum alloy product of  claim 7 , wherein the wrought aluminum alloy products include 0.07-0.15 wt. % Zr and 0.25-0.45 wt. % Mn. 
     
     
         9 . The wrought 7085 aluminum alloy product of  claim 1 , wherein the wrought aluminum alloy products have a thickness of at least 4.0 inches. 
     
     
         10 . The wrought 7085 aluminum alloy product of  claim 9 , wherein the wrought aluminum alloy products have a thickness of not greater than 8.0 inches. 
     
     
         11 . A wrought 7xxx aluminum alloy product having a thickness of 3.0-12.0 inches, comprising:
 0.080-0.250 wt. % Cr;   6.0-10.0 wt. % Zn;   1.3-2.3 wt. % Mg;   1.2-2.6 wt. % Cu;   up to 0.50 wt. % Mn;   up to 0.15 wt. % Zr;   up to 0.15 wt. % Ti;   up to 0.15 wt. % Si; and   up to 0.15 wt. % Fe;   the balance being aluminum and other elements, wherein the wrought 7xxx aluminum alloy product includes not greater than 0.05 wt. % of any one of the other elements, and wherein the wrought 7xxx aluminum alloy product includes not greater than 0.15 wt. % in total of the other elements;   wherein Cr (min) ≦Cr≦Cr (max) , wherein:
   Cr (min) =0.251−0.082(Mg), wherein Cr (min) ≧0.080; and
 
   Cr (max) =0.351−0.082(Mg), wherein Cr (max) ≦0.25.
 
   
     
     
         12 . The wrought 7xxx aluminum alloy product of  claim 11 , comprising 0.15-0.50 wt. % Mn. 
     
     
         13 . The wrought 7xxx aluminum alloy product of  claim 12 , comprising 0.07-0.15 wt. % Zr. 
     
     
         14 . The wrought 7xxx aluminum alloy product of  claim 11 , comprising a sufficient amount of the E phase to realize at least a 10% improvement in typical L-S crack deviation resistance K m , demo as compared to an equivalent 7xxx product, wherein the equivalent 7xxx product is of an equivalent composition, form, thickness and temper as the wrought 7xxx aluminum alloy product, but the equivalent 7xxx product contains not greater than 0.01 wt. % Cr and not greater than 0.02 wt. % Mn. 
     
     
         15 . The wrought 7xxx aluminum alloy product of  claim 14 , comprising a sufficient amount of the E phase and Mn containing dispersoids to realize the at least a 10% improvement in typical L-S crack deviation resistance K max-dev . 
     
     
         16 . The wrought 7xxx aluminum alloy product of  claim 14 , comprising a sufficient amount of the E phase and Al 3 Zr, optionally with Mn containing dispersoids, to realize the at least a 10% improvement in typical L-S crack deviation resistance K max-dev .