Aluminium alloy for lithographic sheet

Abstract

The invention discloses an Al alloy suitable for processing into a lithographic sheet, the alloy having a composition in wt %: Mg 0.05 to 0.30, Mn 0.05 to 0.25, Fe 0.11 to 0.40, Si up to 0.25, Ti up to 0.03, B up to 0.01, Cu up to 0.01, Cr up to 0.03, Zn up to 0.15, unavoidable impurities up to 0.05 each, 0.15 total, Al balance. Also disclosed is a method of processing the Al alloy.

1 . A method of processing an Al alloy having a composition in wt %: 
       
         
           
                 
                 
                 
               
                     
                     
                 
                     
                   Mg 
                   0.05 to 0.30 
                 
                     
                   Mn 
                   0.06 to 0.25 
                 
                     
                   Fe 
                   0.11 to 0.40 
                 
                     
                   Si 
                   up to 0.25 
                 
                     
                   Ti 
                   up to 0.03 
                 
                     
                   B 
                   up to 0.01 
                 
                     
                   Cu 
                   up to 0.01 
                 
                     
                   Cr 
                   up to 0.03 
                 
                     
                   Zn 
                   up to 0.15 
                 
                     
                   Zr 
                   up to 0.005 
                 
                     
                     
                 
             
                
               
               
                
                
                
                
                
                
                
                
                
                
                
               
            
           
         
         Unavoidable impurities up to 0.05 each, 0.15 total 
         Al balance, 
         which method consists of the steps of: casting by DC casting, homogenising, optional hot rolling, cold rolling, and optional interannealing, to give material in H18 or H19 condition, wherein the homogenisation step is carried out by heating the cast alloy to a temperature of 550 to 610° C. for 1 to 10 hours and subsequently cooling to a hot rolling temperature of between 450 and 550° C. 
       
     
     
         2 . A method according to  claim 1 , wherein the method consists of the steps of: casting by DC casting, homogenising, optional hot rolling, and cold rolling, to give material in H19 condition, wherein the homogenisation step is carried out by heating the cast alloy to a temperature of 550 to 610° C. for 1 to 10 hours and subsequently cooling to a hot rolling temperature of between 450 and 550° C. 
     
     
         3 . A method according to  claim 1 , which does not include the optional interannealing step. 
     
     
         4 . A method according to  claim 1 , wherein the interannealing is batch interannealing. 
     
     
         5 . A method according to  claim 4 , wherein the interannealing is carried out at 300 to 500° C. for 1 to 5 hours. 
     
     
         6 . A method according to  claim 1 , wherein the interannealing is continuous interannealing. 
     
     
         7 . A method according to  claim 6 , wherein the continuous interannealing is carried out at 450 to 600° C. for less than 10 minutes. 
     
     
         8 . A method according to  claim 1 , wherein said material in H18 or H19 condition is capable of being electrograined in hydrochloric acid. 
     
     
         9 . A method according to  claim 1 , wherein said material in H18 or H19 condition is capable of being electrograined in nitric acid. 
     
     
         10 . A method according to  claim 1 , wherein said material in H18 or H19 condition is capable of being electrograined in both hydrochloric and nitric acids. 
     
     
         11 . A method of processing an Al alloy having a composition in wt %: 
       
         
           
                 
                 
                 
               
                     
                     
                 
                     
                   Mg 
                   0.05 to 0.30 
                 
                     
                   Mn 
                   0.06 to 0.25 
                 
                     
                   Fe 
                   0.11 to 0.40 
                 
                     
                   Si 
                   up to 0.25 
                 
                     
                   Ti 
                   up to 0.03 
                 
                     
                   B 
                   up to 0.01 
                 
                     
                   Cu 
                   up to 0.01 
                 
                     
                   Cr 
                   up to 0.03 
                 
                     
                   Zn 
                   up to 0.15 
                 
                     
                   Zr 
                   up to 0.005 
                 
                     
                     
                 
             
                
               
               
                
                
                
                
                
                
                
                
                
                
                
               
            
           
         
         Unavoidable impurities up to 0.05 each, 0.15 total 
         Al balance, 
         which method consists of the steps of: casting, homogenising, optional hot rolling, cold rolling, optional interannealing, optional cleaning, electrograining, anodizing and stoving, wherein the homogenisation step is carried out by heating the cast alloy to a temperature of 550 to 610° C. for 1 to 10 hours and subsequently cooling to a hot rolling temperature of between 450 and 550° C. 
       
     
     
         12 . A method of processing an Al alloy having a composition in wt %: 
       
         
           
                 
                 
                 
               
                     
                     
                 
                     
                   Mg 
                   0.05 to 0.30 
                 
                     
                   Mn 
                   0.06 to 0.25 
                 
                     
                   Fe 
                   0.11 to 0.40 
                 
                     
                   Si 
                   up to 0.25 
                 
                     
                   Ti 
                   up to 0.03 
                 
                     
                   B 
                   up to 0.01 
                 
                     
                   Cu 
                   up to 0.01 
                 
                     
                   Cr 
                   up to 0.03 
                 
                     
                   Zn 
                   up to 0.15 
                 
                     
                   Zr 
                   up to 0.005 
                 
                     
                     
                 
             
                
               
               
                
                
                
                
                
                
                
                
                
                
                
               
            
           
         
         Unavoidable impurities up to 0.05 each, 0.15 total 
         Al balance, 
         which method consists of the steps of: casting, homogenising, optional hot rolling, cold rolling, optional interannealing, optional cleaning, electrograining, anodizing and stoving, wherein the homogenisation step is carried out by heating the cast alloy to a temperature of 550 to 610° C. for 1 to 10 hours and subsequently cooling to a hot rolling temperature of between 450 and 550° C., and wherein the steps of casting, homogenising, optional hot rolling, cold rolling, and optional interannealing give material in H18 or H19 condition.