Recrystallized 6XXX Aluminum Alloy with Improved Strength and Formability

Abstract

A substantially recrystallized extrusion may include from about 0.7 to about 1.3 wt % silicon, up to about 0.50 wt % iron, from about 0.03 to about 0.2 wt % copper, up to about 0.5 wt % manganese, from about 0.6 to about 1.2 wt % magnesium, up to about 0.05 wt % chromium, up to about 0.2 wt % zinc, up to about 0.10 wt % titanium and the balance consisting essentially of aluminum and incidental elements and impurities. The disclosed alloy may be homogenized at a temperature above 1030° F. (554.4 ° C.) and have a recrystallized grain structure. Extrusions made from the disclosed alloys and having a wall thickness ranging from about 0.050 to about 0.500 inches (1.5-˜12.5 mm) provides a tensile yield strength of greater than 42 ksi (290 MPa).

What is claimed: 
     
         1 . An aluminum alloy comprising:
 from about 0.7 to about 1.3 wt % silicon,   up to about 0.50 wt % iron,   from about 0.03 to about 0.2 wt % copper,   up to about 0.5 wt % manganese,   from about 0.6 to about 1.2 wt % magnesium,   up to about 0.05 wt % chromium,   up to about 0.2 wt % zinc,   up to about 0.10 wt % titanium, and   the balance consisting essentially of aluminum and incidental elements and impurities.   
     
     
         2 . The alloy of  claim 1  wherein chromium is present in an amount less than 0.02 wt %. 
     
     
         3 . The alloy of  claim 1  wherein manganese is present in an amount less than 0.5 wt %. 
     
     
         4 . The alloy of  claim 1  wherein the alloy is a 6082 alloy. 
     
     
         5 . An extrusion that has a recrystallized grain structure, the extrusion comprising:
 from about 0.7 to about 1.3 wt % silicon,   up to about 0.50 wt % iron,   from about 0.03 to about 0.2 wt % copper,   up to about 0.5 wt % manganese,   from about 0.6 to about 1.2 wt % magnesium,   up to about 0.05 wt % chromium,   up to about 0.2 wt % zinc,   up to about 0.10 wt % titanium, and   the balance consisting essentially of aluminum and incidental elements and impurities.   
     
     
         6 . The extrusion of  claim 5  wherein chromium is present in an amount less than 0.02 wt %. 
     
     
         7 . The extrusion of  claim 5  wherein manganese is present in an amount less than 0.5 wt %. 
     
     
         8 . The extrusion of  claim 5  wherein the extrusion has a tensile yield strength (TYS) of at least at least 42 ksi (290 MPa). 
     
     
         9 . The extrusion of  claim 5  wherein the extrusion has an ultimate tensile strength (UTS) of at least at least 45 ksi (310 MPa). 
     
     
         10 . The extrusion of  claim 5  wherein the extrusion has a tensile yield strength (TYS) of at least at least 42 ksi (290 MPa) and an ultimate tensile strength (UTS) of at least at least 45 ksi (310 MPa). 
     
     
         11 . The extrusion of  claim 5  wherein the extrusion was extruded at an extrusion speed of at least 40 fpm (12.1 m/min) and with a billet temperature of at least 800° F. (426.7° C.). 
     
     
         12 . The extrusion of  claim 5  wherein the extrusion was extruded at an extrusion speed of at least 70 fpm (21.3 m/min) and with a billet temperature of at least 800° F. (426.7° C.). 
     
     
         13 . The extrusion of  claim 5  wherein the extrusion has a thickness ranging from about 0.050 inch to about 0.500 inch (˜1.5-˜12.7 mm) 
     
     
         14 . The extrusion of  claim 5  wherein the extrusion is a 6XXX aluminum alloy. 
     
     
         15 . A method of forming an extrusion having a recrystallized grain structure and a wall thickness ranging from about0.05 to about 0.500 inch (˜1.5-˜12.7 mm), the method comprising:
 providing a billet from an alloy consisting essentially of:
 from about 0.7 to about 1.3 wt % silicon, 
 up to about 0.50 wt % iron, 
 from about 0.03 to about 0.2 wt % copper, 
 up to about 0.5 wt % manganese, 
 from about 0.6 to about 1.2 wt % magnesium, 
 up to about 0.05 wt % chromium, 
 up to about 0.2 wt % zinc, 
 up to about 0.10 wt % titanium, and 
 the balance consisting essentially of aluminum and incidental elements and impurities; 
 
 extruding the billet at a temperature exceeding 800° F. (426.7° C.) and at an extrusion speed exceeding 40 fpm (12.1 m/min) 
 
     
     
         16 . The method of  claim 15  wherein chromium is present in an amount less than 0.02 wt %. 
     
     
         17 . The method of  claim 15  wherein manganese is present in an amount less than 0.5 wt %. 
     
     
         18 . The method of  claim 15  wherein the tube was extruded at an extrusion speed of at least 70 fpm (21.3 m/min) and at a temperature of at least 800° F. (426.7° C.). 
     
     
         19 . The method of  claim 15  wherein the tube was extruded at an extrusion speed of at least 75 fpm (22.86 m/min) and with a billet temperature of at least 875° F. (468.3° C.). 
     
     
         20 . The method of  claim 15  wherein the billet is a 6XXX aluminum alloy.