Low Cost, Substantially Zr-Free Aluminum-Lithium Alloy for Thin Sheet Product with High Formability

Abstract

A low cost, substantially Zr-free, low density 2xxx aluminum-lithium alloy is disclosed. The aluminum-lithium alloy can be produced to high formability sheet products capable of being formed into wrought products with a thickness of 0.01″ to 0.249″. Aluminum-lithium alloys of the invention comprise from 3.2 to 4.1 wt. % Cu, 1.0 to 1.8 wt. % Li, 0.8 to 1.2 wt. % Mg, 0.10 to 0.50 wt. % Zn, 0.10 to 1.0 wt. % Mn, up to 0.12 wt. % Si, up to 0.15 wt. % Fe, up to 0.15 wt. % Ti, up to 0.15 wt. % incidental elements, with the total of these incidental elements not exceeding 0.35 wt. %, and the balance being aluminum. Ag should not be intentionally added and should not be more than 0.1 wt. % as a non-intentionally added element. Zr should not be intentionally added and should not be more than 0.05 wt. % as a non-intentionally added element. Mg is at least equal to or higher than 2*Zn in weight percent in the invented alloy. Methods for manufacturing wrought products including aluminum-lithium alloys of the present invention are also provided.

1 - 33 . (canceled) 
     
     
         34 . A low cost, high formability, substantially Zr-free, Al—Li alloy comprising: 
       
         
           
                 
                 
                 
               
                     
                     
                 
                     
                   from 3.2 to 4.1 wt. % Cu, 
                   from 1.0 to 1.8 wt. % Li, 
                 
                     
                   from 0.8 to 1.2 wt. % Mg, 
                   from 0.10 to 0.50 wt. % Zn, 
                 
                     
                   from 0.1 to 1.0 wt. % Mn, 
                   less than 0.1 wt. % Ag, 
                 
                     
                   less than 0.05 wt. % Zr, 
                   up to 0.15 wt. % Ti, 
                 
                     
                   up to 0.12 wt. % Si, 
                   up to 0.15 wt. % Fe, 
                 
                     
                     
                 
             
                
               
               
                
                
                
                
                
                
               
            
           
         
         up to 0.15 wt. % each incidental elements, with the total of these incidental elements not exceeding 0.35 wt. %, 
         with the balance being aluminum, and 
         wherein Mg content is at least equal to or higher than two times of Zn in weight percent. 
       
     
     
         35 . The aluminum-lithium alloy of  claim 34 , comprising 3.4 to 3.9 wt. % Cu. 
     
     
         36 . The aluminum-lithium alloy of  claim 34 , comprising 1.1 to 1.7 wt. % Li. 
     
     
         37 . The aluminum-lithium alloy of  claim 34 , comprising 0.20 to 0.50 wt. % Zn. 
     
     
         38 . The aluminum-lithium alloy of  claim 34 , comprising 0.2 to 0.6 wt. % Mn. 
     
     
         39 . The aluminum-lithium alloy of  claim 34 , wherein no Zr is intentionally added to the aluminum alloy. 
     
     
         40 . The aluminum-lithium alloy of  claim 34 , comprising a maximum of 0.05 wt. % Ag. 
     
     
         41 . The aluminum-lithium alloy of  claim 34 , comprising a maximum of 0.01 wt. % Ag. 
     
     
         42 . The aluminum-lithium alloy of  claim 34 , wherein no Ag is intentionally added to the aluminum alloy. 
     
     
         43 . The aluminum-lithium alloy of  claim 34 , comprising a maximum 0.05 wt. % Si. 
     
     
         44 . The aluminum-lithium alloy of  claim 34 , comprising a maximum 0.08 wt. % Fe. 
     
     
         45 . The aluminum-lithium alloy of  claim 34 , wherein said aluminum-lithium alloy has a thickness of 0.01-0.249 inch. 
     
     
         46 . The aluminum-lithium alloy of  claim 34 , wherein said aluminum-lithium alloy has a thickness of 0.01-0.125 inch. 
     
     
         47 . A rolled product comprising an aluminum-lithium alloy according to  claim 34 , having a thickness of 0.01″ to 0.249″, exhibiting in a solution heat-treated, quenched and stretched condition a ratio of “soft” to “hard” texture higher than “0.75−0.5*gage” and “0.9−5.0*gage”at sheet quarter thickness (th/4) and center thickness (th/2) respectively, the unit of gage being inch. 
     
     
         48 . A rolled product comprising an aluminum-lithium alloy according to  claim 34 , having a thickness of 0.01″ to 0.249″, exhibiting in a solution heat-treated, quenched and stretched condition a ratio of “soft” to “hard” texture higher than “0.8−0.5*gage” and “1.0−5.0*gage”at sheet quarter thickness (th/4) and center thickness (th/2) respectively, the unit of gage being inch. 
     
     
         49 . The rolled product of  claim 48 , wherein the aluminum-lithium alloy is in the form of a sheet or a coil having a thickness of 0.01″ to 0.125″. 
     
     
         50 . A rolled product comprising an aluminum-lithium alloy according to  claim 34 , having a thickness of 0.01″ to 0.249″, exhibiting in a solution heat-treated, quenched, stretched and artificially aged condition a minimum LT bend ratio of less than “24.30-0.0292*“Specific LT TYS””, and a minimum L bend ratio of less than “13.11-0.0146*“Specific L TYS””, the unit of specific strength being “ksi/(lb/in3)”. 
     
     
         51 . A rolled product comprising an aluminum-lithium alloy according to  claim 34 , having a thickness of 0.01″ to 0.249″, exhibiting in a solution heat-treated, quenched, stretched and artificially aged condition a minimum LT bend ratio of less than “23.65-0.0292*“Specific LT TYS””, and a minimum L bend ratio of less than “12.88-0.0146*“Specific L TYS””, the unit of specific strength being “ksi/(lb/in3)”. 
     
     
         52 . A method of manufacturing a high strength, high formability, low cost aluminum-lithium alloy, the method comprising:
 a. casting stock of an ingot of aluminum alloy comprising the aluminum-lithium alloy product according to  claim 34  producing a cast stock   b. homogenizing the cast stock producing a homogenized cast stock;   c. hot working the homogenized cast stock by one or more methods selected from the group consisting of rolling, extrusion, and forging forming a worked stock;   d. optionally cold rolling the worked stock;   e. solution heat treating (SHT) the optionally cold rolled, worked stock producing a SHT stock;   f. cold water quenching said SHT stock to produce a cold water quenched SHT stock;   g. optionally stretching the cold water quenched SHT stock; and   h. artificially ageing of the cold water quenched, optionally stretched SHT stock.   
     
     
         53 . The method of  claim 52 , wherein said step of homogenizing includes homogenizing at temperatures from 454 to 549° C. (850 to 1020° F.); wherein said step of hot working includes hot rolling at a temperature of 343 to 499° C. (650 to 930° F.); wherein said step of optionally cold work includes cold reduction at 20% to 95%; wherein said step of solution heat treating includes solution heat treated at temperature range from 454 to 543° C. (850 to 1010° F.); wherein said step of optionally stretching includes stretching up to 15%; and wherein said step of ageing includes 121 to 205° F. (250 to 400° F.) and the aging time can be in the range of 2 to 60 hours.