High strength aluminum alloys

Abstract

The invention is a class of new 6XXX series high strength aluminum alloys with a fine grain structure and methods of manufacture and extrusion. Aluminum alloys of the invention comprise from about 0.90 percent to about 1.2 percent by weight silicon, up to about 0.5 percent by weight iron, from about 0.05 percent to about 0.3 percent by weight copper, up to about 0.75 percent by weight manganese, from about 0.70 percent to about 1.0 percent by weight magnesium, up to about 0.25 percent by weight chromium, up to about 0.05 percent by weight zinc, up to about 0.1 percent by weight titanium, with the balance consisting essentially of aluminum. The alloys are cast and homogenized, then extruded, quenched and artificially aged to produce a fine grain crystallization in the final aluminum product exhibiting superior yield strength and elongation properties.

What is claimed: 
     
         1 . An aluminum alloy comprising:
 about 0.90 to about 1.2 weight percent silicon,   up to about 0.5 weight percent iron,   about 0.05 to about 0.30 weight percent copper,   up to about 0.75 weight percent manganese,   about 0.70 to about 1.00 weight percent magnesium,   up to about 0.25 weight percent chromium,   up to about 0.05 weight percent zinc,   up to about 0.10 weight percent titanium, and   the balance consisting essentially of aluminum.   
     
     
         2 . An alloy of  claim 1  wherein each of the elements may vary by about 10%. 
     
     
         3 . An alloy of  claim 1  having a fine grain structure. 
     
     
         4 . An alloy of  claim 1  comprising up to about 0.03 weight percent chromium. 
     
     
         5 . An alloy of  claim 1  comprising up to about 0.20 weight percent manganese. 
     
     
         6 . An alloy of  claim 1  comprising up to about 0.15 weight percent impurities. 
     
     
         7 . An alloy of  claim 1  comprising:
 about 1.13 weight percent silicon, 
 about 0.17 weight percent iron, 
 about 0.16 weight percent copper, 
 about 0.21 weight percent manganese, 
 about 0.80 weight percent magnesium, 
 about 0.004 weight percent chromium, 
 about 0.006 weight percent zinc, 
 about 0.014 weight percent titanium, and 
 the balance consisting essentially of aluminum. 
 
     
     
         8 . An alloy of  claim 7  having a fine grain structure. 
     
     
         9 . An alloy of  claim 7  comprising up to about 0.15 weight percent impurities. 
     
     
         10 . An extrusion that has a fine grain structure, the extrusion comprising:
 about 0.90 to about 1.2 weight percent silicon,   up to about 0.5 weight percent iron,   about 0.05 to about 0.3 weight percent copper,   up to about 0.75 weight percent manganese,   about 0.70 to about 1.0 weight percent magnesium,   up to about 0.25 weight percent chromium,   up to about 0.05 weight percent zinc,   up to about 0.1 weight percent titanium, and   the balance consisting essentially of aluminum.   
     
     
         11 . An extrusion of  claim 10  wherein the extrusion has a tensile yield strength of at least about 290 MPa and an ultimate tensile strength of at least about 310 MPa. 
     
     
         12 . An extrusion of  claim 10  wherein the extrusion has a thickness of about 0.050 inch to about 0.500 inch. 
     
     
         13 . An extrusion of  claim 10  wherein the extrusion is a 6XXX aluminum alloy. 
     
     
         14 . An extrusion of  claim 10  wherein each of the elements may vary by about 10%. 
     
     
         15 . An extrusion of  claim 10  comprising up to about 0.03 weight percent chromium. 
     
     
         16 . An extrusion of  claim 10  comprising up to about 0.20 weight percent manganese. 
     
     
         17 . An extrusion of  claim 10  comprising up to about 0.15 weight percent impurities. 
     
     
         18 . A method of forming aluminum comprising:
 extruding an initial aluminum billet at an initial billet temperature of at least about 800° F. through a press at an extrusion speed of at least about 40 feet per minute; and   obtaining an extruded aluminum material at an exit temperature greater than the initial billet temperature.   
     
     
         19 . A method of  claim 18  further comprising water quenching the extruded aluminum material. 
     
     
         20 . A method of  claim 18  further comprising heating the extruded aluminum material to about 340° F. for about six hours. 
     
     
         21 . A method of  claim 18  where the extruded aluminum material has a tensile yield strength of at least about 320 MPa. 
     
     
         22 . A method of  claim 18  where the extruded aluminum material has a fine grain structure. 
     
     
         23 . A method of  claim 18  where said initial aluminum billet is an alloy comprising:
 about 0.90 to about 1.2 weight percent silicon, 
 up to about 0.5 weight percent iron, 
 about 0.05 to about 0.3 weight percent copper, 
 up to about 0.75 weight percent manganese, 
 about 0.70 to about 1.0 weight percent magnesium, 
 up to about 0.25 weight percent chromium, 
 up to about 0.05 weight percent zinc, 
 up to about 0.1 weight percent titanium, and 
 the balance consisting essentially of aluminum. 
 
     
     
         24 . An method of  claim 23  where said alloy comprises up to about 0.03 weight percent chromium. 
     
     
         25 . An method of  claim 23  where said alloy comprises up to about 0.20 weight percent manganese. 
     
     
         26 . An method of  claim 23  where said alloy comprises up to about 0.15 weight percent impurities.