Pickling method for profiles, rolled strips, and sheets made of aluminium alloys

Abstract

In a method for cleaning a non-machined aluminum alloy product involving alkaline degreasing and treatment thereof after alkaline pickling with an acidic solution, the aluminum alloy product undergoes (a) initial acid cleaning before alkaline degreasing or (b) alkaline degreasing, followed by a subsequent acid rinse, alkaline treatment anew and an additional acid rinse thereafter. The aluminum alloy product may be a rolled aluminum alloy strip, a rolled aluminum alloy sheet and an aluminum alloy profile.

1 . A method for cleaning an aluminum alloy product which has not been machined, comprising:
 cleaning the aluminum alloy product beforehand with an acid,   subsequently degreasing with an alkaline solution, and   thereafter rinsing with an acid.   
     
     
         2 . The method according to  claim 1 , wherein the aluminum alloy product is treated with an alkaline solution before initial acid cleaning. 
     
     
         3 . The method according to  claim 1 , wherein the alkaline solution used for degreasing the aluminum alloy product has a temperature of 50° C. to 85° C. 
     
     
         4 . The method according to  claim 1 , wherein the aluminum alloy product is selected from rolled aluminum alloy strips, from rolled aluminum alloy sheets and from aluminum alloy profiles. 
     
     
         5 . The method according to  claim 1 , wherein the aluminum alloy product used is produced from an aluminum alloy of type AA 5xxx, AA 1xxx, AA 3xxx, AA 6xxx and AA 8xxx according to the International Alloy Designations of The Aluminum Association. 
     
     
         6 . The method according to  claim 1 , wherein the aluminum alloy product that is to be cleaned has undergone intermediate or final annealing. 
     
     
         7 . The method according to  claim 1 , wherein the aluminum alloy product is acid cleaned beforehand for 0.5 to 15 seconds, in particular for 1 to 8 seconds. 
     
     
         8 . The method according to  claim 1 , wherein alkaline degreasing of the aluminum alloy product lasts 1 to 25 seconds, in particular 1.5 to 15 seconds. 
     
     
         9 . The method according to  claim 1 , wherein the aluminum alloy product is acid rinsed for 0.5 to 15 seconds, in particular for 1 to 8 seconds. 
     
     
         10 . The method according to  claim 1 , wherein the surface of the aluminum alloy product is passivated after the acid rinse. 
     
     
         11 . An aluminum alloy product made of an aluminum alloy of class AA 5xxx, AA 1xxx, AA 3xxx, AA 6xxx and AA 8xxx according to the International Alloy Designations of The Aluminum Association, obtainable by any one of the processes of  claim 1 , wherein the aluminum alloy product does not possess any gray to grayish-brown irregularities or imperfections on the surface. 
     
     
         12 . The aluminum alloy product according to  claim 11 , wherein the aluminum alloy product has been annealed before it undergoes cleaning. 
     
     
         11 . The aluminum alloy product according to  claim 11 , wherein the magnesium content is homogeneously distributed across the width of the aluminum alloy product. 
     
     
         14 . The aluminum alloy product according to  claim 11 , wherein the aluminum alloy product is selected from rolled aluminum alloy strips, from rolled aluminum alloy sheets and from aluminum alloy profiles.