Aluminum-lithium alloys, and methods for producing the same

Abstract

New Al—Li alloy bodies and methods of producing the same are disclosed. The new Al—Li alloy bodies may be produced by preparing the aluminum alloy body for post-solutionizing cold work, cold working by at least 25%, and then thermally treating. The new Al—Li alloy bodies may realize improved strength and other properties.

What is claimed is: 
     
         1 . A method comprising:
 (a) preparing an aluminum alloy strip for post-solutionizing cold work,
 (i) wherein the aluminum alloy strip includes 0.25-5.0 wt. % lithium, 
 (ii) wherein the preparing step comprises continuously casting the aluminum alloy sheet, the continuously casting step comprising:
 (A) delivering molten aluminum metal comprising the 0.25-5.0 wt. % lithium to a pair of spaced apart rotating casting rolls defining a nip therebetween; 
 (B) advancing the metal between surfaces of the casting device rolls, wherein the advance comprises:
 (I) first forming two solid outer regions adjacent surfaces of the casting device rolls; 
 (II) second forming a semi-solid inner region containing dendrites of the metal; 
 (III) wherein the inner region is located between the two outer concentration regions; 
 (IV) wherein the first forming and second forming steps are completed concomitant to one another; 
 (V) breaking the dendrites in the inner region at or before the nip; and 
 
 (C) solidifying the semi-solid inner region to produce the aluminum alloy body comprised of the inner region and the outer regions; 
 
 (iii) wherein the preparing step comprises solutionizing of the aluminum alloy strip; 
   (b) after the preparing step (a), cold working the aluminum alloy sheet by at least 25%; and   (c) after the cold working step (b), thermally treating the aluminum alloy sheet;   wherein the cold working and the thermally treating steps are accomplished to achieve an increase in long-transverse tensile yield strength as compared to a reference-version of the aluminum alloy body in the as cold-worked condition.   
     
     
         2 . The method of  claim 1 , wherein the solutionizing step comprises solution heat treating and quenching, wherein the solution heat treating is accomplished due to the continuous casting, and wherein the preparing comprises:
 removing the aluminum alloy strip from a continuous casting apparatus; and   after the removing step, and before the aluminum alloy strip reaches a temperature of 700° F., quenching the aluminum alloy strip, wherein the quenching reduces the temperature of the aluminum alloy strip at a rate of at least 100° F. per second, thereby accomplishing the solutionizing;   wherein the temperature of the aluminum alloy strip exiting the continuous casting apparatus is higher than the temperature of the aluminum alloy strip during the quenching step.   
     
     
         3 . The method of  claim 2 , wherein the quenching comprises cooling the aluminum alloy strip to a temperature of not greater than 150° F. 
     
     
         4 . The method of  claim 3 , wherein the quenching is accomplished by a quenching apparatus downstream of the continuous casting apparatus. 
     
     
         5 . The method of  claim 1 , wherein the cold working comprises cold working the aluminum alloy strip by at least 50%. 
     
     
         6 . The method of  claim 1 , wherein the thermally treating comprises heating the aluminum alloy strip to within 5 ksi of peak strength. 
     
     
         7 . The method of  claim 1 , wherein the preparing and cold working steps are accomplished continuously and in-line. 
     
     
         8 . A method comprising:
 (a) receiving an aluminum alloy body, wherein the aluminum alloy body comprises 0.25-5.0 wt. % lithium, wherein the aluminum alloy body was prepared by solutionizing, and then cold working, wherein the cold working induced at least 25% cold work in the aluminum alloy body, and then first thermally treating to achieve a first predetermined selected condition;   (b) second thermally treating the aluminum alloy body;
 (i) wherein the second thermally treating step is accomplished to achieve a second predetermined selected condition, and such that the aluminum alloy body realizes a higher tensile yield strength over a reference version of the aluminum alloy body in the T6 temper. 
   
     
     
         9 . The method of  claim 8 , comprising:
 forming the aluminum alloy body into a predetermined shaped product.   
     
     
         10 . The method of  claim 9 , wherein the forming occurs during the second thermally treating step. 
     
     
         11 . The method of  claim 8 , wherein the first predetermined selected condition is a predetermined first strength and the second predetermined selected condition is a predetermined second strength. 
     
     
         12 . The method of  claim 11 , wherein the predetermined second strength is higher than the predetermined first strength. 
     
     
         13 . A method comprising:
 (a) receiving a solutionized heat treatable aluminum alloy body, wherein the aluminum alloy body comprises 0.25-5.0 wt. % lithium, wherein the aluminum alloy body was prepared by solutionizing and then cold working, wherein the cold working induced at least 25% cold work in the aluminum alloy body; and   (b) forming the aluminum alloy body into a predetermined shaped product, wherein, during the forming step, the aluminum alloy body is subjected to a temperature in the range of from at least 150° F. to below the recrystallization temperature of the aluminum alloy body.   
     
     
         14 . The method of  claim 13 , wherein the cold working comprises cold rolling the aluminum alloy body to final gauge. 
     
     
         15 . The method of  claim 14 , wherein the predetermined shaped product is a component of a vehicle.