Al-Si-Mn-Mg alloy for forming automotive structural parts by casting and T5 heat treatment

Abstract

An aluminum alloy shaped casting includes about 6.3 wt. % to 9 wt. % silicon, about 0.05 wt. % to 0.4 wt. % magnesium, no more than about 0.8 wt. % manganese, no more than 0.5 wt. % copper, no more than about 1 wt. % zinc, no more than about 0.2 wt. % iron, no more than about 0.2 wt. % titanium, and no more than about 0.04 wt. % strontium, the aluminum alloy shaped casting receiving a T5 heat treatment.

1 . A method of making an aluminum alloy shaped casting, said method comprising: 
 preparing an aluminum alloy melt with a composition substantially within the following ranges: 
 Si: 6.3 wt. %-9 wt. %,  
 Mg: 0.05 wt. %-0.4 wt. %,  
 Mn<0.8wt. %,  
 Cu<0.5 wt. %,  
 Zn<1.0 wt. %,  
 Fe<0.2 wt. %,  
 Ti<0.2 wt. %  
 Sr<0.04wt. %;  
   casting said melt in a mold configured to produce said shaped casting; and    a heat treating step wherein said shaped casting is held at a temperature between about 170 C. and about 400 C. for a time between about 10 minutes and about 180 minutes.    
     
     
         2 . A method, according to  claim 1 , wherein said temperature in said heat treating step is in the range from about 250 C. to about 350 C.  
     
     
         3 . A method, according to  claim 1 , wherein said time in said heat treating step is in the range from about 10 minutes to about 30 minutes.  
     
     
         4 . A method of making an aluminum alloy shaped casting, said method comprising: 
 preparing an aluminum alloy melt with a composition substantially within the following ranges: 
 Si: 6.3 wt. %-9 wt. %,  
 Mg: 0.05 wt. %-0.4 wt. %,  
 Mn<0.8 wt. %,  
 Cu<0.5 wt. %,  
 Zn<1.0 wt. %,  
 Fe<0.2 wt. %,  
 Ti<0.2 wt. %,  
 Sr<0.04 wt. %;  
   thixoforming said melt in a mold configured to produce said shaped casting; and    a heat treating step wherein said shaped casting is held at a temperature between about 170 C. and about 400 C. for a time between about 10 minutes and about 180 minutes.    
     
     
         5 . A method, according to  claim 4 , wherein said temperature in said heat treating step is in the range from about 250 C. to about 350 C.  
     
     
         6 . A method, according to claims  4 , wherein said time in said heat treating step is in the range from about 10 minutes to about 30 minutes.  
     
     
         7 . An aluminum alloy shaped casting having a composition substantially in the range 
 Si: 6.3 wt. %-9 wt. %,    Mg: 0.05 wt. %-0.4 wt. %,    Mn<0.8 wt. %,    Cu<0.5 wt. %,    Zn<1.0 wt. %,    Fe<0.2wt. %,    Ti<0.2 wt. %    Sr<0.04 wt. %;    said aluminum alloy shaped casting receiving a T5 heat treatment.    
     
     
         8 . An aluminum alloy shaped casting, according to  claim 7 , wherein a temperature of said T5 heat treatment is at least about 170 C.  
     
     
         9 . An aluminum alloy shaped casting, according to  claim 7  wherein a temperature of said T5 heat treatment is no more than about 400 C.  
     
     
         10 . An aluminum alloy shaped casting, according to  claim 7 , wherein a temperature of said T5 heat treatment is at least about 250 C.  
     
     
         11 . An aluminum alloy shaped casting, according to  claim 7 , wherein a temperature of said T5 heat treatment is no more than about 350 C.  
     
     
         12 . An aluminum alloy shaped casting, according to  claim 7 , wherein a time of said T5 heat treatment is at least about 10 minutes.  
     
     
         13 . An aluminum alloy shaped casting, according to  claim 7 , wherein a time of said T5 heat treatment is no more than about 180 minutes.  
     
     
         14 . An aluminum alloy shaped casting, according to  claim 7 , wherein a time of said T5 heat treatment is no more than about 30 minutes.  
     
     
         15 . An aluminum alloy shaped casting, according to  claim 7 , wherein said aluminum alloy shaped casting is a vehicle body structure casting.  
     
     
         16 . An aluminum alloy shaped casting, according to  claim 7 , wherein said Si is in a range from about 7 wt. % to about 8.5 wt. %.  
     
     
         17 . An aluminum alloy shaped casting, according to  claim 7 , wherein said Mg is in a range from about 0.1 wt. % to about 0.3 wt. %.  
     
     
         18 . An aluminum alloy shaped casting, according to  claim 7 , wherein said Mn is in a range from about 0.3 wt. % to 0.7 wt. %.  
     
     
         19 . An aluminum alloy shaped casting, according to  claim 7 , wherein said Cu is limited to a maximum of about 0.15 wt. %.  
     
     
         20 . An aluminum alloy shaped casting, according to  claim 7 , wherein said Zn is limited to a maximum of about 0.5 wt. %.  
     
     
         21 . An aluminum alloy shaped casting, according to  claim 7 , wherein said Fe is limited to a maximum of about 0.15 wt. %.  
     
     
         22 . An aluminum alloy shaped casting, according to  claim 7 , wherein said Ti is limited to a maximum of about 0.15 wt. %.  
     
     
         23 . An aluminum alloy shaped casting, according to  claim 7 , wherein said Sr is limited to a maximum of about 0.025 wt. %.  
     
     
         24 . An aluminum alloy shaped casting, according to  claim 7 , further comprising additional elements, wherein each additional element is limited to a maximum of about 0.05 wt. %.  
     
     
         25 . An aluminum alloy shaped casting, according to  claim 7 , further comprising additional elements, wherein a total of said additional elements is limited to a maximum of about 0.15 wt. %.  
     
     
         26 . An aluminum alloy shaped casting, according to  claim 7 , wherein said aluminum alloy shaped casting has a non-dendritic microstructure.