6xxx Alloy With High Recycled Material Content

Abstract

The present invention is directed to a 6xxx series aluminum alloy composition, comprising, consisting essentially of, or consisting of (by weight %) of 0.5-1.5% Si, 0.1-0.7% Cu, 0.5-1.5% Mg, 0.3-1.2% Zn, 0.05-0.35% Cr and allowable impurities of 0.8% Fe, 0.8% Mn, 0.15% Zr, 0.15% Ti, with other elements restricted as unavoidable impurities limited to 0.05% each and 0.15% total with the balance being aluminum. This 6xxx series aluminum alloy is capable of being produced with high amounts of post-consumer recycled material which significantly reduces environmental impact from producing this material, while still meeting and in most cases exceeding material attribute requirements for general engineering applications.

1 . A 6xxx series aluminum alloy having a composition comprising, (by weight %):
 0.5-1.5% Si;   0.1-0.7% Cu;   0.5-1.5% Mg;   0.3-1.2% Zn;   0.050-0.35% Cr;   ≤0.8% Fe;   ≤0.8% Mn;   ≤0.15% Zr;   ≤0.15% Ti;   
       with other elements restricted as unavoidable impurities limited to 0.05% each and ≤0.15% total with the balance being aluminum. 
     
     
         2 . The 6xxx series aluminum alloy of  claim 1  comprising,
 0.8-1.4% Si; 
 0.1-0.7% Cu; 
 0.8-1.4% Mg; 
 0.3-1.1% Zn; 
 0.5.-0.30% Cr; 
 ≤0.6% Fe; 
 ≤0.8% Mn; 
 ≤0.15% Zr; 
 ≤0.15% Ti. 
 
     
     
         3 . The 6xxx series aluminum alloy of  claim 1  including greater than 75% scrap. 
     
     
         4 . The 6xxx series aluminum alloy of  claim 1  including greater than 90% scrap. 
     
     
         5 . An extruded, forged or rolled product manufactured from the 6xxx series aluminum alloy of  claim 1  having a yield tensile strength greater than 295 MPa (42.8 ksi). 
     
     
         6 . An extruded, forged or rolled product manufactured from the 6xxx series aluminum alloy of  claim 1  having a yield tensile strength greater than 320 MPa (46.4 ksi). 
     
     
         7 . An extruded, rolled or forged product manufactured from the 6xxx series aluminum alloy of  claim 1  having excellent machinability performance as defined by achieving a B grade or better in the ASM machinability test. 
     
     
         8 . An extruded, rolled or forged product manufactured from the 6xxx series aluminum alloy of  claim 1  having a thickness of 0.25-10 inches. 
     
     
         9 . An extruded, rolled or forged product manufactured from the 6xxx series aluminum alloy of  claim 8  having a thickness of 1-10 inches. 
     
     
         10 . A method of manufacturing the 6xxx series aluminum alloy of  claim 1  comprising,
 a) casting using conventional direct chill casting methods; 
 b) homogenizing at 950° F. to 1060° F. (510-571° C.) for 2 to 10 hours; 
 c) preheating to 800° F.-1000° F. (427-538° C.); 
 d) hot working by extrusion, forging or rolling; 
 e) water quenching; 
 f) optionally stretching for stress relief and straightening, and 
 g) artificially aging at a temperature between 250-375° F. for 6-20 hours. 
 
     
     
         11 . A method of manufacturing the 6xxx series aluminum alloy of  claim 10 , wherein said hot working is extrusion. 
     
     
         12 . A method of manufacturing the 6xxx series aluminum alloy of  claim 1  comprising,
 a) casting using conventional direct chill casting methods; 
 b) optionally homogenizing at 950° F. to 1060° F. (510-571° C.) for 2 to 10 hours; 
 c) preheating to a rolling temperature of 600° F.-1000° F. (316-538° C.); 
 d) hot rolling; 
 e) solution heat treatment at a temperature of 950° F. to 1070° F., 
 f) quenching to room temperature, 
 g) optionally stretching for stress relief and straightening, and 
 h) artificially aging at a temperature between 250-375° F. for 6-20 hours. 
 
     
     
         13 . A method of manufacturing the 6xxx series aluminum alloy of  claim 1  comprising,
 a) casting using conventional direct chill casting methods; 
 b) homogenizing at 950° F. to 1060° F. (510-571° C.) for 2 to 10 hours; 
 c) preheating to an extrusion temperature of 450° F.-1000° F. (232-538° C.) and then extruding; 
 d) optionally drawing the extrusions; 
 e) solution heat treatment at a temperature of 950° F. to 1070° F., 
 f) quenching to room temperature, 
 g) optionally stretching for stress relief and straightening, and 
 h) artificially aging at a temperature between 250-375° F. for 6-20 hours.