High strength aluminum casting alloy

Abstract

The present invention discloses a high strength Al—Zn—Mg—Cu (7000 series) alloy that can be cast, the cast alloy having a tensile strength of at least 500 megapascals (MPa) and 4% elongation. The cast alloy composition can include about 5.5-9.0 weight percent (wt. %) of zinc, 2.0-3.5 wt. % of magnesium, 0.1-0.5 wt. % scandium, 0.05-0.20 wt. % zirconium, 0.5-3.0 wt. % copper, 0.10-0.45 wt. % manganese, 0.01-0.35 wt. % iron, 0.01-0.20 wt. % silicon with a balance of aluminum and possible casting impurities. The alloy also has good fluidity comparable to high silicon cast aluminum alloys and components can be manufactured using direct chill casting, sand casting, and/or sand casting under high pressure.

1 . A cast aluminum alloy composition comprising:
 between about 5.5 and 9.0 wt % of zinc;   between about 2.0 and 3.5 wt % of magnesium;   between about 0.1 and 0.5 wt % of scandium;   between about 0.05 and 0.20 wt % of zirconium;   between about 0.5 and 3.0 wt % of copper;   between about 0.10 and 0.45 wt % of manganese;   between about 0.08 and 0.35 wt % of iron;   between about 0.07 and 0.20 wt % of silicon; and   balance aluminum and casting impurities,   wherein said cast aluminum alloy has a yield strength of at least 450 MPa, a tensile strength of at least 500 MPa and an elongation of at least 4% at 25° C.   
     
     
         2 . The cast aluminum alloy composition of  claim 1 , wherein said yield strength is at least 475 MPa and said tensile strength is at least 520 MPa. 
     
     
         3 . The cast aluminum alloy composition of  claim 2 , wherein said yield strength is at least 500 MPa and said tensile strength is at least 550 MPa. 
     
     
         4 . The cast aluminum alloy composition of  claim 3 , wherein said elongation is at least 6%. 
     
     
         5 . The cast aluminum alloy composition of  claim 4 , wherein said elongation is at least 10%. 
     
     
         6 . The cast aluminum alloy composition of  claim 1 , wherein said cast aluminum alloy composition is tempered using a tempering treatment selected from a group consisting of: (1) heating at generally 20° C. per hour from generally 50° C. up to 480° C., followed by holding at generally 480° C. for approximately 2 hours, followed by water quenching, followed by holding at generally 120° C. for approximately 19 hours; and (2) heating at generally 20° C. per hour from generally 50° C. up to 480° C., followed by holding at generally 480° C. for approximately 2 hours, followed by water quenching, followed by holding at generally 100° C. for approximately 9 hours, followed by holding at generally 160° C. for approximately 3 hours. 
     
     
         7 . A component made from a cast aluminum alloy according to  claim 1 . 
     
     
         8 . A direct chilled cast component made from a cast aluminum alloy according to  claim 1 . 
     
     
         9 . A sand cast component made from a cast aluminum alloy according to  claim 1 . 
     
     
         10 . A sand cast component hot isostatically pressed made from a cast aluminum alloy according to  claim 1 . 
     
     
         11 . A cast aluminum alloy component comprising:
 a cast aluminum alloy composition having:
 between about 5.5 and 9.0 wt % of zinc; 
 between about 2.0 and 3.5 wt % of magnesium; 
 between about 0.1 and 0.5 wt % of scandium; 
 between about 0.05 and 0.20 wt % of zirconium; 
 between about 0.5 and 3.0 wt % of copper; 
 between about 0.10 and 0.45 wt % of manganese; 
 between about 0.08 and 0.35 wt % of iron; 
 between about 0.07 and 0.20 wt % of silicon; and 
 balance aluminum and casting impurities; 
   wherein said cast aluminum alloy component has tensile properties selected from a group consisting of: (1) yield strength of at least 450 MPa, tensile strength of at least 500 MPa and elongation of at least 4% at 25° C.; and (2) yield strength of at least 550 MPa, tensile strength of at least 650 MPa and elongation of at least 1.5% at −196° C.   
     
     
         12 . The cast aluminum alloy component of  claim 12 , wherein said component is tempered using a tempering treatment selected from a group consisting of (1) heating at generally 20° C. per hour from generally 50° C. up to 480° C., followed by holding at generally 480° C. for approximately 2 hours, followed by water quenching, followed by holding at generally 120° C. for approximately 19 hours; and (2) heating at generally 20° C. per hour from generally 50° C. up to 480° C., followed by holding at generally 480° C. for approximately 2 hours, followed by water quenching, followed by holding at generally 100° C. for approximately 9 hours, followed by holding at generally 160° C. for approximately 3 hours. 
     
     
         13 . The cast aluminum alloy component of  claim 12 , wherein said tensile properties are yield strength of at least 475 MPa, tensile strength of at least 520 MPa and elongation of at least 6% at 25° C. 
     
     
         14 . The cast aluminum alloy component of  claim 12 , wherein said tensile properties are yield strength of at least 500 MPa, tensile strength of at least 550 MPa and elongation of at least 8% at 25° C. 
     
     
         15 . The cast aluminum alloy component of  claim 12 , wherein said tensile properties are yield strength of at least 600 MPa, tensile strength of at least 675 MPa and elongation of at least 1.75% at −196° C. 
     
     
         16 . The cast aluminum alloy component of  claim 15 , wherein said component is a direct chill cast component. 
     
     
         17 . A cast aluminum alloy component comprising:
 a cast aluminum alloy composition having:
 between about 5.5 and 9.0 wt % of zinc; 
 between about 2.0 and 3.5 wt % of magnesium; 
 between about 0.1 and 0.5 wt % of scandium; 
 between about 0.05 and 0.20 wt % of zirconium; 
 between about 0.5 and 3.0 wt % of copper; 
 between about 0.10 and 0.45 wt % of manganese; 
 between about 0.08 and 0.35 wt % of iron; 
 between about 0.07 and 0.20 wt % of silicon; and 
 balance aluminum and casting impurities; 
   wherein said cast aluminum alloy component is a sand cast component and has tensile properties of a yield strength of at least 500 MPa, a tensile strength of at least 535 MPa and elongation of at least 2% at 25° C.   
     
     
         18 . The cast aluminum alloy component of  claim 17 , wherein said component is hot isostatically pressed and has tensile properties of a yield strength of at least 500 MPa, a tensile strength of at least 575 MPa and an elongation of at least 10% at 25° C.