Aluminium alloy, method for producing an aluminium flat product, aluminium flat product and use thereof

Abstract

An aluminium alloy for superplastic aluminium flat products having the following composition: Si≤0.4 wt. %, Fe≤0.4 wt. %, Cu≤0.1 wt. %, 0.5 wt. %≤Mn≤1.0 wt. %, 4.7 wt. %≤Mg≤5.5 wt. %, 0.05 wt. %≤Cr≤0.25 wt. %, Zn≤0.25 wt. %, Ti≤0.20 wt. %, Na≤2 ppm, unavoidable impurities individually ≤0.05 wt. %, in total ≤0.15 wt. %, remainder aluminium. A method for producing an aluminium flat product in which an aluminium melt is provided from the above-mentioned aluminium alloy, in which the aluminium melt is cast to form an ingot, in which the ingot is hot rolled to form a hot strip, in which the hot strip is cold rolled to form a cold strip, and in which the cold strip is levelled. Further disclosed is an aluminium flat product produced by the method and a use thereof.

1 . A method for producing an aluminium flat product, in particular a superplastic aluminium flat product, comprising:
 providing an aluminium melt from an aluminium alloy having the following composition:   
       
         
           
                 
                 
               
                     
                 
                   0.03 wt. % ≤ Si ≤ 
                   0.10 wt. %, 
                 
                   Fe ≤ 
                   0.4 wt. %, 
                 
                   Cu ≤ 
                   0.1 wt. %, 
                 
                   0.5 wt. % ≤ Mn ≤ 
                   1.0 wt. %, 
                 
                   5.2 wt. % ≤ Mg ≤ 
                   5.5 wt. %, 
                 
                   0.05 wt. % ≤ Cr ≤ 
                   0.25 wt. %, 
                 
                   Zn ≤ 
                   0.25 wt. %, 
                 
                   Ti ≤ 
                   0.20 wt. %, 
                 
                   Na ≤ 
                   2 ppm, 
                 
                     
                 
             
                
               
               
                
                
                
                
                
                
                
                
                
                
               
            
           
         
         unavoidable impurities individually ≤0.05 wt. %, in total ≤0.15 wt. %, remainder aluminium, 
         casting the aluminium melt to form an ingot, 
         hot rolling the ingot to form a hot strip, 
         cold rolling the hot strip to form a cold strip, and 
         levelling the cold strip. 
       
     
     
         2 . The method according to  claim 1 , wherein the aluminium alloy has an Fe content of 0.05-0.15 wt. % and/or a Cu content of max. 0.05 wt. %. 
     
     
         3 . The method according to  claim 1 , wherein the aluminium alloy has a Mn content of 0.7 wt. % to 1.0 wt. %. 
     
     
         4 . The method according to  claim 1 , wherein the aluminium alloy has a Zn content of max. 0.06 wt. % and/or a Ti content in the range 0.015-0.03 wt. %. 
     
     
         5 . The method according to  claim 1 , wherein the aluminium alloy has a B content of max. 50 ppm and/or a Ca content of max. 15 ppm and/or a Li content of max. 15 ppm. 
     
     
         6 . The method according to  claim 1 , wherein providing comprises melting together a preliminary aluminium melt with additives to achieve the composition of the molten aluminium, wherein at least two of the alloying elements Cr, Mn and Ti, preferably all three alloying elements Cr, Mn and Ti, are charged separately from one another. 
     
     
         7 . The method according to  claim 1 , wherein the degree of rolling during cold rolling is in total in the range of 70% to 80%, wherein the degree of rolling in the last roll pass is preferably less than 33%. 
     
     
         8 . The method according to  claim 1 , further comprising cutting the cold strip into sheets after levelling without intermediate coiling. 
     
     
         9 . The method according to  claim 1 , wherein the levelling of the cold strip is performed by means of levelling rollers with a diameter of more than 60 mm. 
     
     
         10 . An aluminium flat product, in particular superplastic aluminium flat product, produced by a method according to  claim 1 . 
     
     
         11 . The aluminium flat product according to  claim 10 , wherein the aluminium flat product after a heat treatment for 30 minutes at 500° C. has a yield strength R p0.2  of at least 160 MPa, in particular at least 170 MPa, and a tensile strength R m  of at least 310 MPa, in particular at least 320 MPa. 
     
     
         12 . The aluminium flat product according to  claim 10 , wherein the aluminium flat product after a superplastic forming at a forming temperature of 515° C., a strain rate of 2.5×10 −4 s −1  and a total elongation of 100%, has a porosity of less than 1.5%, in particular less than 1%. 
     
     
         13 . Use of an aluminium flat product according to  claim 10  for producing an aluminium product by superplastic forming of the aluminium flat product, in particular blow moulding. 
     
     
         14 . Use according to  claim 13 , wherein the superplastic forming is performed at a strain rate of at least 10 −3 s −1 , in particular of at least 10 −2 s −1 .