Method for the manufacturing of an aluminium-magnesium-lithium alloy product

Abstract

Method for manufacturing of an aluminium-magnesium-lithium product, comprising the steps of subsequently: (a) providing an aluminium alloy consisting of (in weight %): Mg 3.0-6.0, Li 0.4-3.0, Zn up to 2.0, Mn up to 1.0, Ag up to 0.5, Fe up to 0.3, Si to 0.3, Cu up to 0.3, 0.02-0.5 selected from the group consisting of (Sc 0.010-0.40, Hf 0.010-0.25, Ti 0.010-0.25, V 0.010-0.30, Nd 0.010-0.20, Zr 0.020-0.25, Cr 0.020-0.25, Y 0.005-0.20, Be 0.0002-0.10), balance consisting essentially of aluminium and incidental elements and impurities; (b) casting the aluminium alloy into an ingot; (c) preheating the ingot; (d) hot rolling the preheated ingot to a hot worked intermediate product; (e) cold rolling the hot worked intermediate product to a rolled product in both the length and in the width direction with a total cold rolling reduction of at least 15%; (f) solution heat treating the cold rolled product in the temperature range of 465 to 565° C. for a soaking time in the range of 0.15 to 8 hours; (g) cooling the solution heat treated product from the solution heat treatment temperature to below 150° C. with a cooling rate of at least 0.2° C./sec; (h) ageing the cooled product to provide a sheet or thin plate product having a minimum yield strength of 260 MPa or more and a minimum tensile strength of 400 MPa or more in at least the L- and LT-direction, a minimum yield strength of 230 MPa or more and a minimum tensile strength of 380 MPa or more in the 45° to the L-direction, and further having a minimum T-L fracture toughness K co of 80 MPa.{square root}m or more for 400 mm wide CCT-panels.

1 . Method for manufacturing of an aluminium-magnesium-lithium product, comprising the steps of subsequently: 
 (a) providing an aluminium alloy consisting of (in weight %):                                Mg   3.0-6.0     Li   0.4-3.0     Zn   up to 2.0     Mn   up to 1.0     Ag   up to 0.5     Fe   up to 0.3     Si   up to 0.3     Cu   up to 0.3                   0.02-0.5 selected from the group consisting of   Sc   0.010-0.40 —           Hf   0.010-0.25         Ti   0.010-0.25         V   0.010-0.30         Nd   0.010-0.20         Zr   0.020-0.25         Cr   0.020-0.25         Y   0.005-0.20         Be   0.0002-0.10                                                          balance consisting essentially of aluminium and incidental elements and impurities;    (b) casting the aluminium alloy into an ingot;    (c) preheating the ingot;    (d) hot rolling the preheated ingot to a hot worked intermediate product;    (e) cold rolling the hot worked intermediate product to a rolled product in both the length and in the width direction with a total cold rolling reduction of at least 15%;    (f) solution heat treating the cold rolled product in the temperature range of 465 to 565° C. for a soaking time in the range of 0.15 to 8 hours;    (g) cooling the solution heat treated product from the solution heat treatment temperature to below 150° C. with a cooling rate of at least 0.2° C./sec;    (h) ageing the cooled product to provide a sheet or thin plate product having a minimum yield strength of 260 MPa or more and a minimum tensile strength of 400 MPa or more in at least the L- and LT-direction, a minimum yield strength of 230 MPa or more and a minimum tensile strength of 380 MPa or more in the 45° to the L-direction, and further having a minimum T-L fracture toughness K co  of 80 MPa.{square root}m or more for 400 mm wide CCT-panels.    
     
     
         2 . Method in accordance with  claim 1 , wherein during step (d) the preheated ingot is hot rolled in both the length and in the width direction.  
     
     
         3 . Method in accordance with  claim 1  or  2 , wherein the Mg content is in the range of 4.3 to 5.5 weight %.  
     
     
         4 . Method in accordance with any one of the preceding claims, wherein the Li content is in the range of 1.0 to 2.2 weight %.  
     
     
         5 . Method in accordance with any one of the preceding claims, wherein the Zn content is in the range of 0.2 to 1.0 weight %.  
     
     
         6 . Method in accordance with any one of the preceding claims, wherein the provided aluminium alloy comprises at least Sc in a range of 0.01 to 0.08 weight %.  
     
     
         7 . Method in accordance with  claim 6 , wherein the provided product further comprises at least Zr in a range of 0.02 to 0.25 weight %.  
     
     
         8 . Use of the product obtained by the method in accordance with any one of  claims 1  to  7  as aircraft skin.  
     
     
         9 . Use of the product obtained by the method in accordance with any one of  claims 1  to  7  for the manufacture of aircraft lower wing skins.  
     
     
         10 . An aerospace airframe structure produced from an aluminium-magnesium-lithium product obtained by the method in accordance with any one of  claims 1  to  7 .  
     
     
         11 . Aircraft skin material produced from an aluminium-magnesium-lithium product obtained by the method in accordance with any one of  claims 1  to  7 .