Aluminum alloys with enhanced formability and associated methods

Abstract

Disclosed is an aluminum alloy for aluminum bottle applications, including methods of producing highly shaped aluminum products, such as bottles or cans, formed of the aluminum alloy. In some cases, the aluminum alloy has improved high strain rate formability at elevated temperatures and improved earing, which results in reduced spoilage rates. In one non-limiting example, the disclosed alloys have ε stable values greater than or equal to 0.035, where ε stable =ε F −ε S and ε S represents the strain at which work hardening stage IV starts and ε F represents the strain at which diffuse necking ends. In some cases, the disclosed alloys have an earing balance from about −3.5% to about 2% and a mean earing of less than or equal to 5.5%.

That which is claimed is: 
     
         1 . A method comprising:
 casting an aluminum alloy ingot;   homogenizing the aluminum alloy ingot for form a homogenized aluminum alloy ingot;   hot rolling the homogenized aluminum alloy ingot to form a hot rolled aluminum alloy product;   cold rolling the hot rolled aluminum alloy product in a cold rolling step to form a cold rolled aluminum alloy product, wherein the cold rolling step produces an about 60-99% thickness reduction; and   stabilization annealing the cold rolled aluminum alloy product at a metal temperature from about 100-300° C. for about 0.5-5 hours,   wherein the hot rolling, the cold rolling, and the stabilization annealing steps result in the cold rolled aluminum alloy product comprising an earing balance from about −3.5% to about 2%, a mean earing of less than or equal to 5.5%, a yield strength of about 185-225 Mpa, an ultimate tensile strength of about 205-250 Mpa, a start strain ε S  at which work hardening stage IV starts, and an end strain ε F  at which diffuse necking ends,   wherein an ε stable  is greater than or equal to 0.035, where ε stable =ε F −ε S ,   wherein the earing balance is an earing balance difference between a mean of two heights of a cup formed from the cold rolled aluminum alloy product measured at 180° positions around a circumference of the cup and a mean of four heights of the cup measured at 45° positions around the circumference, and the earing balance difference is divided by a cup height, and   wherein the mean earing a mean earing difference between a peak height and a valley height, and the mean earing difference is divided by the cup height.   
     
     
         2 . The method of  claim 1 , wherein the cold rolling is a first cold rolling step, wherein the cold rolled product is a first cold rolled product, and wherein the method further comprises rolling the first cold rolled product in a second cold rolling step to form a second cold rolled product, wherein the second cold rolling produces an about 15-30% thickness reduction. 
     
     
         3 . The method of  claim 2 , further comprising prior to the second cold rolling step, recrystallization annealing the first cold rolled product, wherein the metal temperature of the recrystallization annealing is from about 290-500° C. for about 0.5-4 hours. 
     
     
         4 . The method of  claim 3 , wherein the metal temperature of the recrystallization annealing is from about 300-450° C. for about 1-2 hours. 
     
     
         5 . The method of  claim 1 , wherein the metal temperature of the stabilization annealing is from about 120-260° C. for about 1-3 hours. 
     
     
         6 . The method of  claim 1 , further comprising shaping the cold rolled aluminum alloy product to form a shaped product, wherein shaping the cold rolled aluminum allow product comprises brim rolling, and wherein the brim rolling step results in the shaped product comprising a spoilage rate less than or equal to 25% due to a brim roll split. 
     
     
         7 . The method of  claim 6 , wherein the shaped product is at least one of an aluminum bottle and an aluminum can. 
     
     
         8 . The method of  claim 1 , wherein:
 the ε stable  is greater than or equal to 0.042;   the earing balance is about −3.0-2%;   the mean earing is less than or equal to 5.0%;   the yield strength is about 190-220 Mpa; and   the ultimate tensile strength is about 210-240 Mpa.   
     
     
         9 . The method of  claim 8 , wherein:
 the ε stable  is greater than or equal to 0.060; and   the earing balance is about −2.5-2%.   
     
     
         10 . The method of  claim 1 , wherein prior to hot rolling, the aluminum alloy has a slab gauge of about 1.1-2.1 inches. 
     
     
         11 . The method of  claim 1 , wherein the hot rolled aluminum alloy product has a hot band (HB) gauge of about 0.12-0.25 inches. 
     
     
         12 . The method of  claim 1 , wherein the cold rolled aluminum alloy product has a ratio of hot rolling strain/cold rolling strain of about 0.50-1.55. 
     
     
         13 . A shaped product comprising:
 an aluminum sheet comprising an alloy having an earing balance from about −3.5% to about 2%, a mean earing of less than or equal to 5.5%, a yield strength of about 185-225 Mpa, an ultimate tensile strength of about 205-250 Mpa, a start strain ε S  at which work hardening stage IV starts, and an end strain ε F  at which diffuse necking ends;   wherein an ε stable  is greater than or equal to 0.035, where ε stable =ε F −ε S ;   wherein the earing balance is an earing balance difference between a mean of two heights of a cup formed from the aluminum sheet measured at 180° positions around a circumference of the cup and a mean of four heights of the cup measured at 45° positions around the circumference, and the earing balance difference is divided by a cup height, and   wherein the mean earing is a mean earing difference between a peak height and a valley height, and the mean earing difference is divided by the cup height.   
     
     
         14 . The shaped product of  claim 13 , wherein the shaped product is at least one of an aluminum bottle and an aluminum can. 
     
     
         15 . The shaped product of  claim 13 , wherein:
 the ε stable  is greater than or equal to 0.042;   the earing balance is about −3.0-2%;   the mean earing is less than or equal to 5.0%;   the yield strength is about 190-220 Mpa;   the ultimate tensile strength is about 210-240 Mpa;   the aluminum sheet has a slab gauge of about 1.1-2.1 inches;   the aluminum sheet has a hot band (HB) gauge of about 0.12-0.25 inches; and   the aluminum sheet has a ratio of hot rolling strain/cold rolling strain of about 0.50-1.55.   
     
     
         16 . The shaped product of  claim 15 , wherein:
 the ε stable  is greater than or equal to 0.060;   the earing balance is about −2.5-2%;   the slab gauge is about 1.2-2.0 inches; and   the ratio of hot rolling strain/cold rolling strain is about 0.60-1.15.   
     
     
         17 . The shaped product of  claim 15 , wherein:
 the slab gauge is about 1.6-2.0 inches; and   the ratio of hot rolling strain/cold rolling strain is about 0.80-1.05.   
     
     
         18 . A method of making the alloy of  claim 13  comprising:
 casting an aluminum ingot; 
 homogenizing the aluminum ingot for form a homogenized ingot; 
 hot rolling the homogenized ingot to form a hot rolled product; 
 cold rolling the hot rolled product in a cold rolling step to form a cold rolled product, wherein the cold rolling step produces an about 60-99% thickness reduction; and 
 stabilization annealing the cold rolled product at a metal temperature from about 100-300° C. for about 0.5-5 hours. 
 
     
     
         19 . The method of  claim 18 , wherein cold rolling is a first cold rolling step, wherein the cold rolled product is a first cold rolled product, and wherein the method further comprises rolling the first cold rolled product in a second cold rolling step to form a second cold rolled product, wherein the second cold rolling produces an about 15-30% thickness reduction. 
     
     
         20 . A method of manufacturing the shaped product of  claim 13  comprising:
 forming the aluminum sheet into a preform; 
 annealing the preform; and 
 shaping the preform to form the shaped product, 
 wherein shaping the preform comprises brim rolling, and 
 wherein a spoilage rate due to a brim roll split during brim rolling is less than or equal to 25%.