Aluminum-copper-lithium alloy products

Abstract

The invention relates to a product made of an aluminium-based alloy comprising, by wt. %, Cu: 2.5-3.4; Li: I.6-2.2; Mg: 0.4-0.9; Mn: 0.2-0.6, Zr: 0.08-0.18; Zn:<0.4; Ag:<0.15; Fe+Si::S 0.20; at least one element selected from Ti, Se, Cr, Hf and V, the content of the element, if selected, being: Ti: O.OI-0.15; Se: O.OI-0.15; Cr: 0.01-0.3; Hf: 0.01-0.5; V: 0.01-0.3; other elements::S 0.05 each and ::S 0.15 in total; the remainder being aluminium. The invention also relates to a method for manufacturing an aluminum alloy-based, extruded, rolled and/or forged product, and a structural element incorporating at least one product as described above.

1 ) A product made of alloy containing aluminum comprising, in % by weight,
 Cu: 2.5-3.4; optionally 2.8-3.2;   Li: 1.6-2.2; optionally 1.65-1.8;   Mg: 0.4-0.9; optionally 0.5-0.8;   Mn: 0.2-0.6; optionally 0.3-0.6;   Zr: 0.08-0.18; optionally 0.12-0.16;   Zn: <0.4 optionally 0.05-0.4; optionally from 0.2-0.4;   Ag: <0.15; optionally <0.1; optionally <0.05;   Fe+Si≤0.20;   at least one element chosen from Ti, Sc, Cr, Hf and V, the concentration of the element, if it is chosen, being:   Ti: 0.01-0.15; optionally 0.01-0.05;   Sc: 0.01-0.15, optionally 0.02-0.1;   Cr: 0.01-0.3, optionally 0.02-0.1;   Hf: 0.01-0.5, optionally 0.02-0.1;   V: 0.01-0.3, optionally 0.01-0.05;   other elements ≤0.05 each and ≤0.15 in total, the rest aluminum.   
     
     
         2 ) The product according to  claim 1 , wherein the concentration of copper is from 2.9 to 3.1% by weight. 
     
     
         3 ) The product according to  claim 1 , wherein the concentration of lithium is from 1.65 to 1.75% by weight. 
     
     
         4 ) The product according to  claim 1 , wherein the concentration of manganese is from 0.4 to 0.6% by weight. 
     
     
         5 ) The product according to  claim 1 , wherein the concentration of zirconium is from 0.14 to 0.15% by weight. 
     
     
         6 ) A method for manufacturing an extruded, rolled and/or forged product containing aluminum alloy, comprising:
 a) producing a bath of liquid metal comprising, in percentage by weight, Cu: 2.5-3.4;   Li: 1.6-2.2; Mg: 0.4-0.9; Mn: 0.2-0.6; Zr: 0.08-0.18; Zn: <0.4; Ag: <0.15; Fe+Si≤0.20; at least one element chosen from Ti, Sc, Cr, Hf and V, the concentration of said element, if it is chosen, being Ti: 0.01-0.15; Sc: 0.01-0.15; Cr: 0.01-0.3; Hf: 0.01-0.5; V: 0.01-0.3; other elements ≤0.05 each and ≤0.15 in total, the rest aluminum   b) casting an unwrought product from said bath of liquid metal;   c) homogenization said unwrought product;   d) hot and, optionally, cold working of the unwrought product into an extruded, rolled and/or forged product;   e) solution heat treatment and quenching of said product;   f) stretching in a controlled manner of said product with a permanent set from 1 to 15%, optionally from 2 to 4%;   g) aging of said extruded product by heating to 140 to 170° C. for 5 to 70 hours in such a way that said product has a conventional elastic limit measured at 0.2% of elongation in the direction L, R p0.2  (L), of at least 510 MPa and a toughness K Q  (L-T), in the direction L-T, of at least 21 MPa√{square root over (m)} and such that K Q  (L-T)>−0.2667*R p0.2  (L)+169.   
     
     
         7 ) The method according to  claim 6 , wherein the temperature of homogenizing is between 520° C. and 530° C. and the treatment time is between 6 and 15 hours. 
     
     
         8 ) The method according to  claim 6 , wherein the aging is carried out at a temperature between 150 to 165° C. for a time with an equivalent t i  at 160° C. between 15 and 28 h, optionally between 20 and 27 h, t i  being defined by the formula: 
       
         
           
             
               
                 t 
                 i 
               
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                       exp 
                        
                       
                         ( 
                         
                           
                             - 
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                            
                           6 
                            
                           400 
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                            
                           T 
                         
                         ) 
                       
                     
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                     d 
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                     t 
                   
                 
                 
                   exp 
                    
                   
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                       6 
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                         T 
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         where T (in Kelvin) is the instantaneous temperature of treatment of the metal, which changes over the time t (in hours), and T ref  is a reference temperature set to 433K. 
       
     
     
         9 ) A product obtained according to a method of  claim 6 , comprising a conventional elastic limit measured at 0.2% of elongation in the direction L, Rp0.2 (L), of at least 525 MPa and a toughness KQ (L-T), in the direction L-T, of at least 23 MPa√m and such that KQ (L-T)>−0.2667*Rp0.2 (L)+171. 
     
     
         10 ) A structural element incorporating at least one product according to  claim 1  or manufactured from a product obtained therefrom. 
     
     
         11 ) The structural element according to  claim 10 , adapted for being used as a stiffener or a frame for manufacturing an airplane-wing lower-surface or upper-surface element, optionally selected from the group consisting of stiffeners, spars and ribs, floor beams and seat rails.