Al-Zn-Mg-Ag high-strength alloy for aerospace and automotive castings

Abstract

An aluminum casting alloy comprises, in weight percent: about 4-5% Zn; about 1-3% Mg; about 0-1% Cu; less than about 0.3% Si; less than about 0.12% Fe; less than about 0.5% Mn; about 0.01-0.05 wt % B; less than about 0.15% Ti; about 0.05-0.2% Zr; about 0.1-0.5% Ag; no more than about 0.05% each miscellaneous element or impurity; no more than about 0.15% total miscellaneous elements or impurities; balance aluminum. The alloy may advantageously be used in either T5 or T6 tempers.

1 . An aluminum casting alloy comprising, in weight percent: 
 about 4 to about 5% Zn;    about 1 to about 3% Mg;    up to about 1% Cu;    less than about 0.3% Si;    less than about 0.12% Fe;    less than about 0.5% Mn;    about 0.01 to about 0.05 wt % B;    less than about 0.15% Ti;    about 0.05 to about 0.2% Zr;    about 0.1 to about 0.5% Ag;    no more than about 0.05% each miscellaneous element or impurity;    no more than about 0.15% total miscellaneous elements or impurities;    balance aluminum.    
   
   
       2 . An aluminum casting alloy according to  claim 1  wherein a concentration of said zinc is about 4.5%.  
   
   
       3 . An aluminum casting alloy according to  claim 1  wherein a concentration of said magnesium is about 1.2%.  
   
   
       4 . An aluminum casting alloy according to  claim 1  wherein a concentration of said titanium is about 0.06%.  
   
   
       5 . An aluminum casting alloy according to  claim 1  wherein a concentration of said boron is about 0.02%.  
   
   
       6 . An aluminum casting alloy according to  claim 1  wherein a concentration of said zirconium is about 0.13%.  
   
   
       7 . An aluminum casting alloy according to  claim 1  wherein a concentration of said silver is about 0.3%.  
   
   
       8 . A method of making an aluminum alloy casting, said method comprising: 
 preparing an aluminum alloy melt, said melt comprising, in    weight percent:    about 4 to about 5% Zn;    about 1 to about 3% Mg;    up to about 1% Cu;    less than about 0.3% Si;    less than about 0.12% Fe;    less than about 0.5% Mn;    about 0.01 to about 0.05 wt % B;    less than about 0.15% Ti;    about 0.05 to about 0.2% Zr;    about 0.1 to about 0.5% Ag;    no more than about 0.05% each miscellaneous element or impurity;    no more than about 0.15% total miscellaneous elements or impurities; and balance aluminum;    casting at least a portion of said melt in a mold configured to form said casting; and    removing said casting from said mold.    
   
   
       9 . A method according to  claim 8  further comprising subjecting said casting to an artificial ageing heat treatment.  
   
   
       10 . A method according to  claim 8  further comprising subjecting said casting to a solution heat treatment.  
   
   
       11 . A method according to  claim 10  further comprising subjecting said casting to an artificial ageing heat treatment following said solution heat treatment.  
   
   
       12 . A shaped aluminum alloy casting, said casting comprising, in weight percent: 
 about 4 to about 5% Zn;    about 1 to about 3% Mg;    up to about 1% Cu;    less than about 0.3% Si;    less than about 0.12% Fe;    less than about 0.5% Mn;    about 0.01 to about 0.05 wt % B;    less than about 0.15% Ti;    about 0.05 to about 0.2% Zr;    about 0.1 to about 0.5% Ag;    no more than about 0.05% each miscellaneous element or impurity;    no more than about 0.15% total miscellaneous elements or impurities balance aluminum.    
   
   
       13 . An aluminum alloy casting according to  claim 12  wherein a concentration of said zinc is about 4.5%.  
   
   
       14 . An aluminum alloy casting according to  claim 12  wherein a concentration of said magnesium is about 1.2%.  
   
   
       15 . An aluminum alloy casting according to  claim 12  wherein a concentration of said titanium is about 0.06%.  
   
   
       16 . An aluminum alloy casting according to  claim 12  wherein a concentration of said boron is about 0.02%.  
   
   
       17 . An aluminum alloy casting according to  claim 12  wherein a concentration of said zirconium is about 0.13%.  
   
   
       18 . An aluminum alloy casting according to  claim 12  wherein a concentration of said silver is about 0.3%.