Lower wing skin metal with improved damage tolerance properties

Abstract

The invention relates to a rolled product with state T351, having thickness of between 15 and 50 mm, made from aluminium alloy having the following composition, in % by weight, Cu: 3.85-4.15; Mg: 0.95-1.25; Mn: 0.45-0.57; Zr: 0.09-0.16; Ti: 0.005-0.1; Fe: <0.070; Si: <0.060; with Cu+Mg≤5.15; other lesser elements 0.05 each and less than 0.15 in total, the remainder being aluminium.

1 . A manufacturing process for a rolled product in T351 temper, comprising:
 preparing and casting an aluminum alloy of thickness from 15 to 50 mm comprising, as a percentage by weight,   Cu: 3.85-4.15,   Mg: 0.95-1.25,   Mn: 0.45-0.57,   Zr: 0.09-0.16,   Ti: 0.005-0.1,   Fe: <0.070,   Si: <0.060,   with Cu+Mg 5≤5.15,   other elements <0.05 each and less than 0.15 in total, the remainder being aluminum;   adding a grain-refining agent of AlTiB type to obtain a rolling slab;   optionally homogenizing said slab at a temperature from 480° C. to 510° C.;   optionally hot rolling said homogenized slab to obtain a plate of thickness e from 15 to 50 mm;   solution heat treating said plate at a temperature from 480 to 505° C. for a time t in hours such that t≥e/7;   quenching said solution heat treated plate;   cold stretching said quenched plate with a deformation of from 1.5 to 3%; and   carrying out natural aging at room temperature.   
     
     
         2 . The process according to  claim 1 , wherein said solution heat treatment is performed at a temperature from 495° C. to 505° C. 
     
     
         3 . The process according to  claim 2 , wherein said time t is such that t≤e/t≤4.5. 
     
     
         4 . The process according to  claim 2 , wherein said time t is such that t≤e/5.0. 
     
     
         5 . The process according to  claim 2 , wherein said time t is such that t≤e/5.5. 
     
     
         6 . The method according to  claim 1 , wherein hot rolling is performed. 
     
     
         7 . The method according to  claim 6 , wherein an average temperature during hot rolling to thickness 60 mm is at least 450° C. 
     
     
         8 . The method according to  claim 6 , wherein during hot rolling, an outgoing temperature is at least 410° C. 
     
     
         9 . The method according to  claim 1 , wherein homogenizing is performed. 
     
     
         10 . The method according to  claim 6 , wherein homogenizing is performed. 
     
     
         11 . The method according to  claim 9 , wherein homogenizing occurs at a temperature in a range from 480 to 510° C. 
     
     
         12 . The method according to  claim 9 , wherein homogenizing occurs at a temperature in a range from 490 to 508° C. 
     
     
         13 . The method according to  claim 1 , wherein thickness e is in a range from 20 to 40 mm. 
     
     
         14 . The method according to  claim 1 , wherein the plate has a ratio of UTS(L) to TYS(L) at 0.2% elongation greater than 1.25. 
     
     
         15 . The method according to  claim 14 , wherein the ratio is greater than 1.30. 
     
     
         16 . The method according to  claim 14 , wherein TYS(L) at 0.2% elongation is at least 350 MPa. 
     
     
         17 . The method according to  claim 14 , wherein TYS(L) at 0.2% elongation is at least 365 MPa. 
     
     
         18 . An aluminum rolled product in T351 temper, prepared by the process according to  claim 1 . 
     
     
         19 . An aluminum rolled product in T351 temper, prepared by the process according to  claim 10 . 
     
     
         20 . The aluminum rolled product of  claim 18 , wherein TYS(L) at 0.2% elongation is at least 350 MPa.