Aluminum alloy, cast article of aluminum alloy, and method for producing cast article of aluminum alloy

Abstract

An aluminum alloy according to the present invention includes from 4.0 to 6.0% Mg, from 0.3 to 0.6% Mn, from 0.5 to 0.9% Fe, and the balance of Al and inevitable impurities when the entirety is taken as 100% by mass. By appropriately selecting the composition range of Mg, Mn and Fe, it has been possible to micro-finely crystallize Al (Mn, Fe) compounds while inhibiting the growth of primary-crystal Al. As a result, the resulting aluminum alloy is good in terms of the castability, and shows high strength as well as high ductility.

1 . An aluminum alloy for cast products, comprising: 
 from 4.0 to 6.0% magnesium (Mg);    from 0.3 to 0.5% manganese (Mn);    from 0.5 to 0.9% iron (Fe);    from 0.1 to 0.2% titanium (Ti); and    the balance of aluminum (Al) and inevitable impurities when the entirety is taken as 100% by mass (mass percentage).    
     
     
         2 . The aluminum alloy for cast products set forth in  claim 1  further comprising from 0.1 to 0.7% chromium (Cr) when the entirety is taken as 100% by mass.  
     
     
         3 . (Cancelled).  
     
     
         4 . The aluminum alloy for cast products set forth in  claim 1  further comprising from 0.01 to 0.05% boron (B) when the entirety is taken as 100% by mass.  
     
     
         5 . The aluminum alloy for cast products set forth in  claim 1  further comprising from 0.001 to 0.01% beryllium (Be) when the entirety is taken as 100% by mass.  
     
     
         6 . The aluminum alloy for cast products set forth in  claim 1  further comprising from 0.05 to 0.3% molybdenum (Mo) when the entirety is taken as 100% by mass.  
     
     
         7 . The aluminum alloy for cast products set forth in  claim 1 , wherein said inevitable impurities comprise 0.50 or less silicon (Si) and 0.3% or less copper (Cu) when the entirety is taken as 100% by mass.  
     
     
         8 . The aluminum alloy for cast products set forth in  claim 1  wherein said Fe is from 0.5 to 0.8% by mass.  
     
     
         9 . The aluminum alloy for cast products set forth in  claim 1 , further comprising primary-crystal aluminum and compounds which are dispersed uniformly, the primary-crystal aluminum having a dendritic cell size of 10 μm or less, the compounds having a grain diameter of 5 μm or less.  
     
     
         10 . The aluminum alloy for cast products set forth in  claim 1 , which exhibits a tensile strength of 250 MPa or more as cast being free from being subjected to a heat treatment after casting.  
     
     
         11 . The aluminum alloy for cast products set forth in  claim 1 , which exhibits a 0.2% proof stress of 130 MPa or more as cast being free from being subjected to a heat treatment after casting.  
     
     
         12 . The aluminum alloy for cast products set forth in  claim 1 , which exhibits a fracture elongation of 13% or more as cast being free from being subjected to a heat treatment after casting.  
     
     
         13 . A cast product made of an aluminum alloy, the cast product comprising: 
 from 4.0 to 6.0% magnesium (Mg);    from 0.3 to 0.5% manganese (Mn);    from 0.5 to 0.9% iron (Fe);    from 0.1 to 0.2% titanium (Ti); and    the balance of Al and inevitable impurities when the entirety is taken as 100% by mass.    
     
     
         14 . A process for producing a cast product made of an aluminum alloy, the process comprising the steps of: 
 pouring an aluminum alloy molten metal into a die, the aluminum alloy molten metal comprising: 
 from 4.0 to 6.0% magnesium (Mg);  
 from 0.3 to 0.5% manganese (Mn);  
 from 0.5 to 0.9% iron (Fe);  
 from 0.1 to 0.2% titanium (Ti); and  
 the balance of Al and inevitable impurities when the entirety is taken as 100% by mass; and  
   solidifying the aluminum alloy molten metal by cooling it after the pouring step.    
     
     
         15 . The process for producing a cast product made of an aluminum alloy set forth in  claim 14 , wherein said solidifying step is a step being solidified by cooling at a cooling rate of 20° C./sec. or more.