6xxx aluminum alloys

Abstract

New 6xxx aluminum alloy products and methods and systems of making the same are disclosed. A method may include heating a billet of a 6xxx aluminum alloy to a preheat temperature, holding the billet at the preheat temperature for a time sufficient to dissolve at least some precipitate hardening phases of the billet, extruding the billet into an extruded product wherein, during the extruding, both the billet and the extruded product are maintained at or above the preheat temperature, discharging the extruded product from the extrusion apparatus while maintaining the extruded product within 100° F. of a solvus temperature of the 6xxx aluminum alloy, and moving the extruded product from the heating shroud to a quenching apparatus.

What is claimed is: 
     
         1 . A 6xxx extruded product comprising:
 from 0.2 to 2.0 wt. % Si;   from 0.2 to 1.5 wt. % Mg;   one of either:
 (i) from 0.07 to 1.0 wt. % Mn; or 
 (ii) less than 0.07 wt. % Mn; 
   up to 1.5 wt. % Bi;   up to 1.5 wt. % Sn;   up to 1.0 wt. % Cu;   up to 1.0 wt. % Zn;   up to 0.7 wt. % Pb;   up to 0.7 wt. % Fe;   up to 0.35 wt. % Cr;   up to 0.35 wt. % V;   up to 0.25 wt. % Zr;   up to 0.20 wt. % Ti;   the balance being aluminum, optional incidental elements and impurities;   wherein, when the 6xxx extruded product includes from 0.07 to 1.0 wt. % Mn, the 6xxx extruded product comprises an unrecrystallized microstructure as measured from T/10 to 9T/10 of the 6xxx extruded product;   wherein the unrecrystallized microstructure comprises at least 50 vol. % unrecrystallized grains;   wherein at least 60% of the unrecrystallized grains are fibrous grains;   wherein the fibrous grains have an aspect ratio (grain length/diameter) of at least 5:1;   wherein the average grain size of the unrecrystallized microstructure is not greater than 200 microns; or   
       wherein, when the 6xxx extruded product includes less than 0.07 wt. % Mn, the 6xxx extruded product comprises a recrystallized microstructure as measured from T/10 to 9T/10 of the 6xxx extruded product;
 wherein the recrystallized microstructure comprises at least 50 vol. % recrystallized grains; 
 wherein at least 60% of the recrystallized grains are equiaxed grains having as aspect ratio of not greater than 5:1 (L:LT); 
 wherein the average grain size of the recrystallized microstructure is not greater than 200 microns. 
 
     
     
         2 . The 6xxx extruded product of  claim 1 , wherein the 6xxx extruded product comprises at least 1 vol. % more cube (ED) texture as compared to a conventional 6xxx extruded product;
 wherein the conventional 6xxx extruded product is conventionally press-quenched and is of a comparable composition, product form, size and temper.   
     
     
         3 . The 6xxx extruded product of  claim 2 , wherein the 6xxx extruded product comprises at least 2 vol. % more cube (ED) texture as compared to the conventional 6xxx extruded product. 
     
     
         4 . The 6xxx extruded product of  claim 2 , wherein the 6xxx extruded product comprises a maximum ODF [001] texture intensity, wherein the maximum ODF [001] texture intensity is at least 10% higher than a maximum ODF [001] texture intensity of a conventional 6xxx extruded product;
 wherein the conventional 6xxx extruded product is conventionally press-quenched and is of a comparable composition, product form, size and temper.   
     
     
         5 . The 6xxx extruded product of  claim 4 , wherein the extruded 6xxx extruded product realizes a maximum ODF [001] texture intensity that is at least about 20% higher than the conventional 6xxx extruded product. 
     
     
         6 . A method comprising:
 (a) heating a billet of a 6xxx aluminum alloy to a preheat temperature;   (b) holding the billet at the preheat temperature for a time sufficient to dissolve at least some precipitate hardening phases of the billet;   (c) after the holding step, immediately transferring the billet to an extrusion apparatus;   (d) extruding the billet into an extruded product in the extrusion apparatus, wherein, during the extruding, both the billet and the extruded product are maintained at or above the preheat temperature;   (e) discharging the extruded product from the extrusion apparatus and into an exit shroud, wherein the exit shroud maintains the extruded product within 100° F. of a solvus temperature of the 6xxx aluminum alloy;   (f) moving the extruded product from the heating shroud to a quenching apparatus, wherein the quenching apparatus comprises at least one of a water spray and a water bath, and wherein the quenching apparatus quenches the extruded product to a temperature below 125° F. and at a cooling rate of at least 1° F./second.   
     
     
         7 . A system comprising:
 (a) a furnace adapted to preheat an extrusion billet of a 6xxx aluminum alloy;   (b) an extrusion apparatus adjacent to and downstream of the furnace, wherein the extrusion apparatus is adapted to extrude the billet into an extruded product;   (c) an exit shroud adjacent to and downstream of the extrusion apparatus, wherein the exit shroud is adapted to maintain the extruded product within 100° F. of a solvus temperature of the 6xxx aluminum alloy;   (d) a quenching apparatus located immediately adjacent to and downstream of the extrusion apparatus, wherein the quenching apparatus is adapted to cool the extruded product received from the exit shroud to a temperature below 125° F. and at a cooling rate of at least 1° F./second.