Castable aluminum alloy

Abstract

A castable aluminum alloy includes, in weight %, 0 to about 19% Si, 0 to about 5.0% Cu, 0 to about 1.5% Mg, up to about 3.0% Zn, up to about 2.0% Ni, up to about 0.3% Ti, greater than 0 to about 1.5 weight % Fe, about 0.2% to about 3.0% Mn, wherein a weight ratio of Mn/Fe is 0.6 or greater when Fe is less than 0.4 weight % and the weight ratio of Mn/Fe is 1.0 or greater when Fe is equal to or greater than 0.4 weight % to reduce porosity and increase tensile strength of a casting made from the alloy.

1 . A castable aluminum alloy comprising, in weight %, 0 to about 19% Si, 0 to about 5.0% Cu, 0 to about 1.5% Mg, up to about 3.0% Zn, up to about 2.0% Ni, up to about 0.3% Ti, greater than 0 to about 1.5 weight % Fe, about 0.2% to about 3.0% Mn, wherein a weight ratio of Mn/Fe is at least 0.6 when Fe is less than 0.4 weight % and the weight ratio of Mn/Fe is at least 1.0 when Fe is equal to or greater than 0.4 weight % to reduce porosity and improve tensile strength of a casting made from the alloy.  
     
     
         2 . The alloy of  claim 1  wherein the Fe concentration is about 0.4 weight % or greater.  
     
     
         3 . The alloy of  claim 1  wherein the Cu concentration is about 2.5 weight % or greater.  
     
     
         4 . The alloy of  claim 1  which further comprises at least one of Sr or a rare earth metal.  
     
     
         5 . A castable aluminum alloy comprising, in weight %, 0 to 9.0% Si, 0 to about 5.0% Cu, about 0.15% to about 0.6% Mg, up to about 1.0% Zn, up to about 0.3% Ti, about 0.2% to about 0.8% Fe, about 0.3% to about 1.2% Mn, and balance Al, wherein a weight ratio of Mn/Fe is 0.6 or greater when Fe is less than 0.4 weight % and the weight ratio is 1.0 or greater when Fe is equal to or greater than 0.4 weight %.  
     
     
         6 . The alloy of  claim 5  wherein the Fe concentration is about 0.4 weight % to about 0.8 weight %.  
     
     
         7 . The alloy of  claim 5  consisting essentially of, in weight %, about 5.0 to about 7.0% Si, about 2.5% to about 4.0% Cu, about 0.15% to about 0.35% Mg, up to about 0.5% Zn, up to about 0.3% Ti, about 0.35% to about 0.65% Fe, about 0.4% to about 0.9% Mn, and balance Al, wherein the weight ratio of Mn/Fe is 0.6 or greater when Fe is less than 0.4 weight % and is 1.0 or greater when Fe is equal to or greater than 0.4 weight %.  
     
     
         8 . The alloy of  claim 7  which further comprises about 0.01% to about 0.025% Sr.  
     
     
         9 . The alloy of  claim 5  consisting essentially of, in weight %, 0 to about 0.25% Si, about 3 to about 5% Cu, about 0.1% to about 0.3% Mg, up to about 0.5% Zn, up to about 0.3% Ti, greater than 0 to about 0.5% Fe, about 0.2% to about 0.8% Mn, and balance Al, wherein a weight ratio of Mn/Fe is 0.6 or greater when Fe is less than 0.4 weight % and the weight ratio of Mn/Fe is 1.0 or greater when Fe is equal to or greater than 0.4 weight %.  
     
     
         10 . The alloy of  claim 9  which further comprises at least one of Sr up to about 0.05 weight % or a rare earth metal up to 5 weight.  
     
     
         11 . The alloy of  claim 5  consisting essentially of, in weight %, about 6.0 to 9.0% Si, 0 to about 0.75% Cu, about 0.2% to about 0.4% Mg, up to about 1.0% Zn, 0 to about 1.5% Ni, up to 0.3% Ti, about 0.35% to about 0.65% Fe, about 0.4% to about 0.9% Mn, and balance Al, wherein the weight ratio of Mn/Fe is 0.6 or greater when Fe is less than 0.4 weight % and is 1.0 or greater when Fe is 0.4 weight % or more.  
     
     
         12 . The alloy of  claim 11  which further comprises about 0.005% to about 0.025% Sr.  
     
     
         13 . A casting, comprising, in weight %, 0 to about 19% Si, 0 to about 5.0% Cu, 0 to about 1.5% Mg, up to about 3.0% Zn, up to about 2.0% Ni, up to about 0.3% Ti, greater than 0 to about 1.5 weight % Fe, about 0.2% to about 3.0% Mn, wherein a weight ratio of Mn/Fe is 0.6 or greater when Fe is less than 0.4 weight % and the weight ratio of Mn/Fe is 1.0 or greater when Fe is equal to or greater than 0.4 weight % to reduce porosity and improve tensile strength of the casting.  
     
     
         14 . The casting of  claim 13  which comprises an engine cylinder block or engine cylinder head.  
     
     
         15 . The casting of  claim 13  which is precipitation hardened.  
     
     
         16 . A method of casting, comprising melting a castable aluminum alloy comprising, in weight %, 0 to about 19% Si, 0 to about 5.0% Cu, 0 to about 1.5% Mg, up to about 3.0% Zn, up to about 2.0% Ni, up to about 0.3% Ti, greater than 0 to about 1.5 weight % Fe, about 0.2% to about 3.0% Mn, wherein a weight ratio of Mn/Fe is 0.6 or greater when Fe is less than 0.4 weight % and the weight ratio of Mn/Fe is 1.0 or greater when Fe is equal to or greater than 0.4 weight %, introducing the melted alloy into a mold, and solidifying the melted alloy in the mold to form a casting wherein said ratio reduces porosity and increases tensile strength of the casting.  
     
     
         17 . The method of  claim 16  wherein a cast engine cylinder block or cylinder head is formed in the mold.