Heat treatable Al-Zn-Mg alloy for aerospace and automotive castings

Abstract

A heat treatable aluminum alloy for shaped castings includes from about 3.5-5.5% Zn, from about 1-1.5% Mg, less than about 1% Si, less than about 0.30% Mn, and less than about 0.3% Fe and other incidental impurities.

1 . A heat treatable aluminum alloy for shaped castings, said aluminum alloy comprising, in weight percent, alloying ingredients as follows: 
 Zn: about 3.5-5.5%;    Mg: about 0.8-1.5%;    Si: less than about 1%;    Mn: less than about 0.30%; and    Fe and other incidental impurities: less than about 0.30%.    
   
   
       2 . An aluminum alloy according to  claim 1  further comprising at least one grain refiner selected from the group consisting of boron, carbon and combinations thereof.  
   
   
       3 . An aluminum alloy according to  claim 2 , wherein said at least one grain refiner includes boron in a range from about 0.0025 to about 0.05%.  
   
   
       4 . An aluminum alloy according to  claim 2 , wherein said at least one grain refiner includes carbon in a range from about 0.0025 to about 0.05%.  
   
   
       5 . An aluminum alloy according to  claim 1  further comprising at least one anti-recrystallization agent selected from the group consisting of zirconium, scandium and combinations thereof.  
   
   
       6 . An aluminum alloy according to  claim 5  wherein said at least one anti-recrystallization agent includes zirconium in a range below 0.2%.  
   
   
       7 . An aluminum alloy according to  claim 5  wherein said at least one anti-recrystallization agent includes scandium in a range below 0.3%.  
   
   
       8 . An aluminum alloy according to  claim 1  wherein said zinc is at a concentration of about 4.2 to 4.8%.  
   
   
       9 . An aluminum alloy according to  claim 1  wherein said zinc is at a concentration of about 4.4 to 4.6%.  
   
   
       10 . An aluminum alloy according to  claim 1  wherein said magnesium is at a concentration of about 1.0 to 1.4%.  
   
   
       11 . An aluminum alloy according to  claim 10  wherein said magnesium is at a concentration of about 1.1 to 1.3%.  
   
   
       12 . An aluminum alloy according to  claim 1  wherein a concentration of iron in said alloy is less than about 0.3%.  
   
   
       13 . An aluminum alloy according to  claim 1  wherein a concentration of manganese in said alloy is less than about 0.3%.  
   
   
       14 . A shaped casting of an aluminum alloy, wherein said alloy comprises alloying ingredients as follows: 
 Zn: about 3.5-5.5%;    Mg: about 0.8-1.5%;    Si: less than about 1%;    Mn: less than about 0.30%; and    Fe and other incidental impurities: less than about 0.30%.    
   
   
       15 . A shaped casting according to  claim 14  after T5 heat treatment.  
   
   
       16 . A shaped casting according to  claim 14  after T6 heat treatment.  
   
   
       17 . A shaped casting according to  claim 14  wherein said zinc is at a concentration of about 4.2 to 4.8%.  
   
   
       18 . A shaped casting according to  claim 14  wherein said zinc is at a concentration of about 4.4 to 4.6%.  
   
   
       19 . A shaped casting according to  claim 14  wherein said magnesium is at a concentration of about 1.0 to 1.4%.  
   
   
       20 . A shaped casting according to  claim 14  wherein said magnesium is at a concentration of about 1.1 to 1.3%.  
   
   
       21 . A method of making an aluminum alloy shaped casting, said method comprising: 
 preparing a molten mass of an aluminum alloy, said alloy comprising alloying ingredients as follows:    Zn: about 3.5-5.5%;    Mg: about 0.8-1.5%;    Si: less than about 1%;    Mn: less than about 0.30%;    Fe and other incidental impurities: less than about 0.30%;    casting at least a portion of said molten mass in a mold configured to produce said shaped casting;    permitting said molten mass in said mold to solidify; and    removing said shaped casting from said mold.    
   
   
       22 . A method according to  claim 21  further comprising subjecting said shaped casting to a T5 heat treatment.  
   
   
       23 . A method according to  claim 21  further comprising subjecting said shaped casting to a T6 heat treatment.  
   
   
       24 . A method according to  claim 21  wherein said zinc is at a concentration of about 4.2 to 4.8%.  
   
   
       25 . A method according to  claim 21  wherein said zinc is at a concentration of about 4.4-4.6%.  
   
   
       26 . A method according to  claim 21  wherein said magnesium is at a concentration of about 1.0 to 1.4%.  
   
   
       27 . A method according to  claim 21  wherein said magnesium is at a concentration of about 1.1 to 1.3%.