Method for grain refinement of high strength aluminum casting alloys

Abstract

An improved aluminum base alloy having improved hot crack resistance when solidified into cast products, the alloy comprised of 4 to 5.5 wt. % Cu, max. 0.5 wt. % Mn, max. 0.55 wt. % Mg, max. 0.2 wt. % Si, up to 0.5 wt. % Fe, optionally 1.13 to 1.7 wt. % Ni, 0.005 to 0.12 wt. % Ti, the balance comprised of aluminum, incidental elements and impurities.

What is claimed is:  
     
         1 . An improved aluminum base alloy casting having improved hot cracking resistance in the as-cast condition, the alloy comprised of 4 to less than 5 wt. % Cu, 0.15 to 0.55 wt. % Mg, 0.2 to 0.5 wt. % Mn, 0.015 to 0.2 wt. % Si, 0.015 to 0.5 wt. % Fe, 0.01 to 0.12 wt. % Ti, the balance comprised of aluminum, incidental elements and impurities, cast products formed from the alloy having a grain size of less than 125 microns.  
     
     
         2 . A near net shape cast product formed from an aluminum base alloy, the cast product having increased resistance to hot cracking in the as-cast condition, the alloy comprised of 4 to less than 5 wt. % Cu, 0.15 to 0.55 wt. % Mg, 0.2 to 0.5 wt. % Mn, 0.015 to 0.2 wt. % Si, 0.015 to 0.5 wt. % Fe, 0.01 to 0.12 wt. % Ti, the balance comprised of aluminum, incidental elements and impurities, the cast product having a grain size of less than 125 μm.  
     
     
         3 . A method of casting an aluminum base alloy to provide a cast product having improved hot crack resistance in the as-cast condition and a grain size of less than 125 microns, the method comprising: 
 (a) providing an aluminum base alloy comprised of 4 to less than 5 wt. % Cu, 0.15 to 0.55 wt. % Mg, 0.2 to 0.5 wt. % Mn, 0.015 to 0.2 wt. % Si, 0.015 to 0.5 wt. % Fe, the balance comprised of aluminum, incidental elements and impurities;    (b) maintaining Ti in the range of 0.005 to 0.12 wt. % to improve the resistance of said alloy to hot cracking;    (c) adding a nucleating agent selected from the group consisting of carbides, aluminides and borides; and    (d) solidifying said alloy to provide a cast product substantially free of hot cracks.    
     
     
         4 . An improved vehicular or aerospace casting having increased resistance to hot cracking, the member formed from an aluminum alloy comprised of 4 to less than 5 wt. % Cu, 0.15 to 0.55 wt. % Mg, 0.2 to 0.5 wt. % Mn, 0. 015 to 0.2 wt. % Si, 0.015 to 0.5 wt. % Fe, 0.01 to 0.12 wt. % Ti, the balance comprised of aluminum, incidental elements and impurities, the casting having a grain size of less than 125 microns.  
     
     
         5 . A near net shape cast vehicular casting formed from an aluminum base alloy, the vehicular casting having increased resistance to hot cracking, the alloy comprised of 4 to 5.5 wt. % Cu, 0.15 to 0.55 wt. % Mg, 0.2 to 0.5 wt. % Mn, 0.015 to 0.2 wt. % Si, 0.015 to 0.5 wt. % Fe, 0.01 to 0.12 wt. % Ti, the balance comprised of aluminum, incidental elements and impurities, the casting having a grain size of less than 125 μm.  
     
     
         6 . A near net shape cast aircraft casting formed from an aluminum base alloy, the aircraft casting having increased resistance to hot cracking, the alloy comprised of 4 to 5.5 wt. % Cu, 0.15 to 0.55 wt. % Mg, 0.2 to 0.5 wt. % Mn, 0.015 to 0.2 wt. % Si, 0.015 to 0.5 wt. % Fe, 0.01 to 0.12 wt. % Ti, the balance comprised of aluminum, incidental elements and impurities, the casting having a grain size of less than 125 μm.