Aluminum alloy products having improved property combinations and method for artificially aging same

Abstract

Aluminum alloy products about 4 inches thick or less that possesses the ability to achieve, when solution heat treated, quenched, and artificially aged, and in parts made from the products, an improved combination of strength, fracture toughness and corrosion resistance, the alloy consisting essentially of: about 6.8 to about 8.5 wt. % Zn, about 1.5 to about 2.00 wt. % Mg, about 1.75 to about 2.3 wt. % Cu; about 0.05 to about 0.3 wt. % Zr, less than about 0.1 wt. % Mn, less than about 0.05 wt. % Cr, the balance Al, incidental elements and impurities and a method for making same. The instantly disclosed alloys are useful in making structural members for commercial airplanes including, but not limited to, upper wing skins and stringers, spar caps, spar webs and ribs of either built-up or integral construction.

What is claimed is: 
     
         1 . A method comprising:
 (a) casting a 7xxx aluminum alloy ingot, wherein the 7xxx aluminum alloy ingot comprises from 6.8 to 8.5 wt. % Zn, from 1.5 to 2.0 wt. % Mg, and 1.75 to 2.3 wt. % Cu;   (b) after step (a), homogenizing the 7xxx aluminum alloy ingot;   (c) after step (b), hot working the ingot into a wrought product;   (d) after step (c), solution heat treating and then quenching the wrought product;   (e) after step (d), stress relieving the wrought product;   (f) after step (e), artificially aging the wrought product to one of a T73, T74, T76 or T79 temper.   
     
     
         2 . The method of  claim 1 , wherein the aluminum alloy ingot comprises 7.5-8.5 wt. % Zn, 1.9-2.3 wt. % Cu, and 1.5-2.0 wt. % Mg. 
     
     
         3 . The method of  claim 1 , wherein the aluminum alloy ingot comprises 7.8-8.5 wt. % Zn, 1.95-2.25 wt. % Cu, and 1.7-2.0 wt. % Mg. 
     
     
         4 . The method of  claim 1 , wherein the aluminum alloy ingot comprises 7.9-8.2 wt. % Zn, 2.05-2.15 wt. % Cu, and 1.75-1.85 wt. % Mg. 
     
     
         5 . The method of  claim 1 , wherein the aluminum alloy ingot comprises 7.4-8.0 wt. % Zn, 1.95-2.25 wt. % Cu, and 1.7-2.0 wt. % Mg. 
     
     
         6 . The method of  claim 1 , wherein the aluminum alloy ingot comprises 7.5-7.9 wt. % Zn, 2.05-2.20 wt. % Cu, and 1.8-1.9 wt. % Mg. 
     
     
         7 . The method of  claim 1 , wherein the aluminum alloy ingot comprises 7.4-8.0 wt. % Zn, 1.9-2.3 wt. % Cu, and 1.55-2.0 wt. % Mg. 
     
     
         8 . The method of  claim 1 , wherein the aluminum alloy ingot comprises 7.5-7.9 wt. % Zn, 2.05-2.20 wt. % Cu, and 1.6-1.75 wt. % Mg. 
     
     
         9 . The method of  claim 1 , wherein the hot working step comprises hot working the ingot into a wrought product having a thickness of from 2.00 inches to 4 inches. 
     
     
         10 . The method of  claim 1 , wherein the wrought product is a first wrought product, wherein the method comprises:
 joining the first wrought product to a second aluminum alloy product, thereby producing a joined product.   
     
     
         11 . The method of  claim 10 , wherein the second aluminum alloy product comprises the same composition as the first wrought product. 
     
     
         12 . The method of  claim 10 , wherein the second aluminum alloy product comprises a different composition than the first wrought product. 
     
     
         13 . The method of  claim 10 , wherein the joining step occurs after the artificial aging step (f). 
     
     
         14 . The method of  claim 13 , wherein the second aluminum alloy product comprises the same temper as the first wrought product. 
     
     
         15 . The method of  claim 13 , wherein the second aluminum alloy product comprises a different temper than the first wrought product. 
     
     
         16 . The method of  claim 10 , comprising:
 after the joining step, age forming the joined product into an aerospace structural component.   
     
     
         17 . The method of  claim 10 , wherein the joining comprises welding. 
     
     
         18 . The method of  claim 17 , wherein the welding comprises friction stir welding. 
     
     
         19 . The method of  claim 1 , comprising:
 age forming the wrought product into an aerospace structural component.   
     
     
         20 . The method of  claim 1 , comprising:
 reinforcing the wrought product with a fiber metal laminate product.