Aluminum-zinc-magnesium-copper alloy extrusion

Abstract

An aluminum alloy extrusion product having improved strength and fracture toughness, the aluminum base alloy comprised of 1.95 to 2.5 wt. % Cu, 1.9 to 2.5 wt. % Mg, 8.2 to 10 wt. % Zn, 0.05 to 0.25 wt. % Zr, max. 0.15 wt. % Si, max. 0.15 wt. % Fe, max. 0.1 wt. % Mn, the remainder aluminum and incidental elements and impurities.

1 . A method of producing an aluminum alloy extrusion product having improved fracture toughness, the method comprising the steps of: 
 (a) providing a molten body of an aluminum base alloy comprised of 1.95 to 2.5 wt. % Cu, 1.95 to 2.5 wt. % Mg, 8.2 to 10 wt. % Zn, 0.05 to 0.25 wt. % Zr, max. 0.15 wt. % Si, max. 0.15 wt. % Fe, max. 0.1 wt. % Mn, the remainder aluminum and incidental elements and impurities;    (b) casting said molten body of said aluminum base alloy to provide a solidified body, said molten aluminum base alloy being cast at a rate in the range of 1 to 6 inches per minute;    (c) homogenizing said body by heating in a first temperature range of 840 to 860° F. followed by heating in a second temperature range of 860° to 880° F., the second homogenization temperature being greater than the first temperature to provide a homogenized body having a uniform distribution of q precipitate and zirconium containing dispersoids;    (d) extruding said homogenized body to provide an extrusion, said extruding being carried out in a temperature range of 600° to 850° F. and at a rate sufficient to maintain at least 80% of the cross-sectional area of said extrusion in a non-recrystallized condition;    (e) solution heat treating said extrusion; and    
   
   
       1 - 38 . (canceled)  
   
   
       39 . An improved aluminum base alloy wrought product consisting essentially of 1.95 to 2.5 wt. % Cu, 1.9 to 2.5 wt. % Mg, 8.2 to 10 wt. % Zn, 0.05 to 0.25 wt. % Zr, max. 0.15 wt. % Si, max. 0.15 wt. % Fe, max. 0.1 wt. % Mn, the remainder aluminum and incidental elements and impurities, said alloy product having a fracture toughness of 5% or greater and a yield strength of 8% or greater than a similarly sized 7075 product.  
   
   
       40 . The alloy product in accordance with  claim 39  wherein the alloy contains 1.95 to 2.3 wt. % Cu.  
   
   
       41 . The alloy product in accordance with  claim 39  wherein the alloy contains 1.9 to 2.3 wt. % Mg.  
   
   
       42 . The alloy product in accordance with  claim 39  wherein the alloy contains 0.05 to 0.2 wt. % Cr.  
   
   
       43 . The alloy product in accordance with  claim 39  wherein the alloy contains 8.45 to 9.4 wt. % Zn.  
   
   
       44 . The alloy product in accordance with  claim 39  wherein the alloy contains 0.01 to 0.2 wt. %. Sc.  
   
   
       45 . The alloy product in accordance with  claim 39  wherein the alloy contains 0.01 to 0.2 wt. % Ti.  
   
   
       46 . The alloy product in accordance with  claim 39  wherein said product is an extrusion product.  
   
   
       47 . The alloy product in accordance with  claim 39  wherein the alloy product is an extrusion having an aspect ratio between the thinnest and the thickest section of 1:4 to 1:18.  
   
   
       48 . The alloy product in accordance with  claim 39  wherein said product is an aircraft stringer.  
   
   
       49 . The alloy product in accordance with  claim 39  wherein said product is an aircraft floor beam.  
   
   
       50 . The alloy product in accordance with  claim 39  wherein said product is an aircraft fuselage beam.  
   
   
       51 . The alloy product in accordance with  claim 39  wherein said product is a hollow extruded product.  
   
   
       52 . The alloy product in accordance with  claim 39  wherein said product is a hollow non-seamless extruded product.  
   
   
       53 . The alloy product in accordance with  claim 39  wherein said product is a hollow seamless extruded product.  
   
   
       54 . The alloy product in accordance with  claim 39  wherein said product is a baseball bat.  
   
   
       55 . The alloy product in accordance with  claim 39  wherein said product is an automobile rocker arm.  
   
   
       56 . An improved aluminum base alloy wrought product consisting essentially of 1.95 to 2.5 wt. % Cu, 1.9 to 2.5 wt. % Mg, 8.2 to 10 wt. % Zn, 0.05 to 0.25 wt. % Zr, 0.05 to 0.2 wt. % Sc, max 0.15 wt. % Si, max. 0.15 wt. % Fe, max. 0.1 wt. % Mn, the remainder aluminum and incidental elements and impurities.  
   
   
       57 . The alloy product in accordance with  claim 56  wherein the alloy contains 0.05 to 0.2 wt. % Cr.  
   
   
       58 . The alloy product in accordance with  claim 56  wherein the alloy contains 0.05 to 0.2 wt. % Ti.  
   
   
       59 . An improved aluminum base alloy wrought product consisting essentially of 1.95 to 2.5 wt. % Cu, 1.9 to 2.5 wt. % Mg, 8.2 to 10 wt. % Zn, 0.05 to 0.25 wt. % Zr, max. 0.15 wt. % Si, max. 0.15 wt. % Fe, max. 0.1 wt. % Mn, the remainder aluminum and incidental elements and impurities, said alloy product having a yield strength to fracture toughness ratio of 5% or greater, a yield strength of 8% or greater than a similarly sized 7075 product and having an exfoliation resistance of EB or better.  
   
   
       60 . An improved aluminum base alloy aircraft member consisting essentially of 1.95 to 2.5 wt. % Cu, 1.9 to 2.5 wt. % Mg, 8.2 to 10 wt. % Zn, 0.05 to 0.25 wt. % Zr, max. 0.15 wt. % Si, max. 0.15 wt. % Fe, max. 0.1 wt. % Mn, the remainder aluminum and incidental elements and impurities, said alloy product having a fracture toughness of 5% or greater and a yield strength of 8% or greater than a similarly sized 7075 product.  
   
   
       61 . The alloy product in accordance with  claim 60  wherein said member is an aircraft stringer.  
   
   
       62 . The alloy product in accordance with  claim 60  wherein said member is an aircraft floor beam.  
   
   
       63 . The alloy product in accordance with  claim 60  wherein said member is an aircraft fuselage beam.  
   
   
       64 . An improved aluminum base alloy aircraft member consisting essentially of 1.95 to 2.5 wt. % Cu, 1.9 to 2.5 wt. % Mg, 8.2 to 10 wt. % Zn, 0.05 to 0.25 wt. % Zr, max. 0.15 wt. % Si, max. 0.15 wt. % Fe, max. 0.1 wt. % Mn, the remainder aluminum and incidental elements and impurities, said alloy product having a yield strength to fracture toughness ratio of 8% or greater than a similarly sized 7075 product and having an exfoliation resistance of EB or better.  
   
   
       65 . (canceled)  
   
   
       66 . The improved aluminum base alloy product in accordance with  claim 39  wherein said product is a sheet product.  
   
   
       67 . The improved aluminum base alloy product in accordance with  claim 39  wherein said product is a plate product