Method of manufacturing formed pieces of type 2024 aluminum alloy

Abstract

This invention relates to a method of manufacturing highly worked pieces of AlCuMg alloy, comprising the steps of: a) casting a plate composed of (weight per cent): Cu: 3.8-4.5 Mg: 1.2-1.5 Mn: 0.3-0.5 Si<0.25 Fe<0.20 Zn<0.20 Cr<0.10 Zr<0.10 Ti<0.10, b) possibly homogenizing at a temperature between 460 and 510° C. for 2 to 12 hrs, and preferably at a temperature between 470 and 500° C. for a duration for 3 to 6 hrs, c) hot rolling at an input temperature between 430 and 470° C., and preferably between 440 and 460° C., d) cutting out sheets, e) forming in one or several processes, such as stretch forming, drawing, flow spinning, or bending, f) solution treating between 480 and 500° C., for a duration between 5 min and 1 hr, g) quenching, wherein forming can take place before and after solution treatment and quenching. The invention is applicable in particular for manufacturing aircraft fuselage panels.

1 . A method of manufacturing highly worked pieces of AlCuMg alloy, comprising the steps of: 
 a) casting a plate composed of (weight per cent): 
 Cu: 3.8-4.5 mg: 1.2-1.5 mn: 0.3-0.5 Si<0.25 Fe<0.20 Zn<0.20 Cr<0.10 Zr<0.10 Ti<0.10  
   b) possibly homogenizing at a temperature between 460 and 510° C. for 2 to 12 hrs, and preferably at a temperature of 470 and 500° C. for a duration of 3 to 6 hrs,    c) hot rolling at an input temperature between 430 and 470° C., and preferably between 440 and 460° C.,    d) possibly cold rolling the coil,    e) possibly annealing the coil at a temperature between 350 and 450° C.,    f) cutting out sheets,    g) solution treating between 480 and 500° C., for a duration between 5 min and 1 hr,    h) quenching,    i) forming in one or several processes, such as stretch forming, drawing, flow spinning, or bending, wherein such forming may also take place after step f).    
     
     
         2 . The method according to  claim 1 , characterized in that a first forming takes place before solution treatment and in that, after solution treatment and quenching, the formed piece is submitted to the following process: 
 a) possibly immediately transferring the piece in as quenched condition into a cold chamber at a temperature of less than 10° C., and preferably of less than 0° C.,    b) less than one hour after quenching or leaving the cold chamber, another sheet forming in one or several processes, such as stretch forming, drawing, flow spinning, or bending.    
     
     
         3 . The method of manufacturing highly worked pieces of AlCuMg alloy according to  claim 1 , comprising sheet manufacturing through the following steps: 
 a) casting a plate composed of (weight per cent) Cu: 3.8-4.5 Mg: 1.2-1.5 Mn: 0.3-0.5 Si<0.25 Fe<0.20 Zn<0.20 Cr<0.10 Zr<0.10 Ti<0.10,    b) possibly homogenizing at a temperature between 460 and 510° C. for 2 to 12 hrs, and preferably at a temperature between 470 and 500° C. for a duration of 3 to 6 hrs,    c) hot rolling at an input temperature between 430 and 470° C., and preferably between 440 and 460° C.,    d) cutting out sheets,    wherein, in the L and LT directions, the sheets have an ultimate elongation A greater than 13.5%, and preferably greater than 15%, and are used for manufacturing highly worked pieces through the following steps: 
 e) sheet forming in one or several processes, such as stretch forming, drawing, flow spinning, or bending,  
 f) solution treating formed pieces at a temperature between 480 and 500° C., for a duration of 5 min and 1 hr,  
 g) quenching.  
   
     
     
         4 . The method according to any of  claims 1  to  3 , characterized in that the sheet is cladded on one side or on both sides with another sheet of aluminium alloy.  
     
     
         5 . The method according to any of  claims 3  to  4 , characterized in that the hot rolling output temperature is >300° C., and preferably >310° C.  
     
     
         6 . The method according to any of  claims 1  to  5 , characterized in that cold rolling is carried out between hot rolling and sheet cutting.  
     
     
         7 . The method according to any of  claims 1  to  6 , characterized in that Cu content is between 3.9 and 4.3%, and preferably between 3.9 and 4.2%.  
     
     
         8 . The method according to any of  claims 1  to  7 , characterized in that Mg content is between 1.2 and 1.4%, and preferably between 1.25 and 1.35%.  
     
     
         9 . The method according to any of  claims 1  to  8 , characterized in that Mn content is between 0.30 and 0.45%.  
     
     
         10 . The method according to any of  claims 1  to  9 , characterized in that Si content is less than 0.10%, and preferably less than 0.08%.  
     
     
         11 . The method according to any of  claims 1  to  10 , characterized in that Fe content is less than 0.10%.  
     
     
         12 . The method according to any of  claims 1  to  11 , characterized in that Zn<0.20%, Cr<0.07%, and preferably <0.05%, Zr<0.07%, and preferably <0.05%, Ti 0.07%, and preferably <0.05%.  
     
     
         13 . The method of manufacturing highly worked pieces of AlCuMg alloy according to  claim 1 , comprising the following steps of: 
 a) casting a plate composed of (weight per cent): 
 Cu: 3.8-4.5 Mg: 1.2-1.5 Mn: 0.3-0.5 Si<0.25 Fe<0.20 Zn<0.20 Cr<0.10 Zr<0.10 Ti<0.10,  
   b) possibly homogenizing at a temperature between 460 and 510° C. for 2 to 12 hrs, and preferably at a temperature between 470 and 500° C. for a duration of 3 to 6 hrs,    c) hot rolling at an input temperature between 430 and 470° C., and preferably between 440 and 460° C.,    d) possibly cold rolling,    e) cutting out sheets,    f) solution treating the sheets at 480 to 500° C. for a duration of 5 min and 1 hr,    g) quenching,    h) forming the sheets in one or several processes, such as stretch forming, drawing, flow spinning, or bending.    
     
     
         14 . The method according to  claim 13 , characterized in that Cu content is between 3.9 and 4.3%, and preferably between 3.9 and 4.2%.  
     
     
         15 . The method according to any of claims  13  or  14 , characterized in that Mg content is between 1.2 and 1.4%, and preferably between 1.25 and 1.35%.  
     
     
         16 . The method according to any of claims  13  or  15 , characterized in that Mn content is between 0.30 and 0.45%.  
     
     
         17 . The method of manufacturing highly worked pieces of AlCuMg alloy according to any of  claims 13  to  16 , comprising sheet manufacturing through the following steps: 
 a) casting a plate composed of (weight per cent): 
 Cu: 4-4.5 Mg: 1.25-1.45 Mn: 0.30-0.45 Si<0.10 Fe<0.20 Zn<0.20 Cr<0.05 Zr<0.03 Ti<0.05,  
 
 b) possibly homogenizing at a temperature between 460 and 510° C. for 2 to 12 hrs, and preferably at a temperature between 470 and 500° C. for a duration of 3 to 6 hrs,  
 c) hot rolling at an input temperature between 430 and 470° C., and preferably between 440 and 460° C.,  
 d) possibly cold rolling,  
 e) cutting out sheets,  
 f) solution treating the sheets at a temperature between 480 and 500° C. for 5 min to 1 hr,  
 g) quenching,  
 wherein the sheets are used for manufacturing highly worked pieces in one or several processes, such as stretch forming, drawing, flow spinning, or bending.  
 
     
     
         18 . The process to any of  claims 13  to  17 , characterized in that forming is carried out less than one hour after quenching.  
     
     
         19 . The method according to any of  claims 13  to  17 , characterized in that between quenching and forming, the sheet in as quenched condition is stored in a cold chamber at a temperature of less than 0°C.  
     
     
         20 . The method according to any of  claims 18  to  19 , characterized in that, for a thickness of 5 mm, the hot rolled sheet has a forming limit diagram characterized by a value ε 1 >0.18 for L=300 mm, or ε 1 >0.22 for L=500 mm.  
     
     
         21 . The method according to any of claims  13  and  17 , characterized in that between quenching and forming, cold working is performed through rolling or smooth out, followed by controlled stretching with permanent set between 0.5 and 5%.  
     
     
         22 . The method according to  claim 21 , characterized in that the sheet that was solution treated, quenched, cold worked through rolling or smooth out, and possibly stretched with permanent set between 0.5 and 5% has at least one of the following sets of properties: 
 a) a mean value of the three elongation A values measured in the directions TL, L and at 45°, greater than 20% and preferably greater than 22%, and    a mean value of the three values R p0.2  measured in the directions TL, L and at 45°, greater than 305 MPa, and    an LDH value greater than 72 mm for a thickness of 1.6 mm, or an LDH value greater than 76 mm for a thickness of 3.2 mm, or an LDH value greater than 80 mm for a thickness between 4 and 7 mm;    b) a mean value of the three values R p0.2  measured in the directions TL, L and at 45°, greater than 305 MPa, and    a mean value of the three values Ag measured in the directions TL, L and at 45°, greater than 18%;    c) a mean value of the three elongation A values measured in the directions TL, L and at 45°, greater than A>22%, and    a mean value of the three values R p0.2  measured in the directions TL, L and at 45°, greater than 305 MPa, and    a mean value of the three values Ag% measured in the directions TL, L and at 45°, greater than 18%;    d) a mean value of the three values R p0.2  measured in the directions TL, L and at 45°, greater than 305 MPa, and    a mean value of the three plane stretching Atp values measured in the directions TL, L and at 45°, greater than 18%,    an LDH value greater than 72 mm for a thickness of 1.6 mm, or an LDH value greater than 76 mm for a thickness of 3.2 mm, or an LDH value greater than 80 mm for a thickness between 4 and 7 mm.    
     
     
         23 . The method according to any of claims  21  and  22 , characterized in that the sheet that was solution treated, quenched, cold worked through rolling or smooth out and possibly stretched with permanent set between 0.5 and 5% has at least one of the three following properties: 
 a) the LDH value is greater than 40 mm for a thickness of less than 4 mm, or greater than 74 mm for a thickness greater than 4 mm,  
 b) the forming limit diagram shows a coefficient ε 1 >0,18 for L=500 mm for a thickness between 1.4 mm and 2 mm,  
 c) the forming limit diagram shows a coefficient ε 1 >0,35 for L=500 mm for a thickness between 5.5 mm and 8 mm.  
 
     
     
         24 . The method according to any of  claims 21  to  23 , characterized in that the sheet that was solution treated, quenched, cold worked through rolling or smooth out and possibly stretched with permanent set between 0.5 and 5% has at least one of the following properties: 
 a) K c  (L-T)>120 MPa{square root}m  
 b) K c0  (L-T)>90 MPa{square root}m  
 c) K c  (T-L)>125 MPa{square root}m  
 d) K c0  (T-L)>80 MPa{square root}m