Electro-assisted pickling of steel

Abstract

A pickling process of a metallic strip is provided including the steps of: passing said metallic strip through at least a pickling bath being at a temperature between 1 and 100° C., applying an alternating current, having a current density of 1x102 to 1x105 A.m−2 of unit surface of said metallic strip to said metallic strip passing through said at least one pickling bath.

What is claimed is: 
     
         1 - 11  (canceled) 
     
     
         12 . A pickling process of a metallic strip comprising the steps of:
 passing the metallic strip through a pickling bath being at a temperature between 1 and 100° C.;   applying an alternating current on the metallic strip passing through the pickling bath, the alternating current applying a current density of 1×10 2  to 1×10 5  A.m −2  of unit surface of said metallic strip to said metallic strip passing through the pickling bath, the alternating current having an anodic period and a cathodic period with a cathodic/anodic pulse length ratio of 0.1 and 5.0.   
     
     
         13 . The pickling process as recited in  claim 12  wherein the metallic strip is made of steel. 
     
     
         14 . The pickling process as recited in  claim 12  wherein the metallic strip passes through the bath at a speed between 10 m.min −1  and 450 m.min −1 . 
     
     
         15 . The pickling process as recited in  claim 12  wherein the pickling bath has a temperature of at least 40° C. 
     
     
         16 . The pickling process as recited in  claim 12  wherein the pickling bath has a pickling acid or pickling salt concentration of at least 30 g.L −1 . 
     
     
         17 . The pickling process as recited in  claim 12  wherein the pickling bath has a pickling acid or pickling salt concentration of at least 60 g.L −1 . 
     
     
         18 . The pickling process as recited in  claim 12  wherein the current density is at least 1×10 3  A.m −1 . 
     
     
         19 . The pickling process as recited in  claim 12  wherein the alternating current has a frequency between 0.5 and 100 Hz. 
     
     
         20 . The pickling process as recited in  claim 12  wherein the alternating current has a frequency of at least 15 Hz. 
     
     
         21 . The pickling process as recited in  claim 20  wherein the alternating current has a frequency of at most 50 Hz. 
     
     
         22 . The pickling process as recited in  claim 12  wherein the alternating current has a frequency of at most 50 Hz. 
     
     
         22 . The pickling process as recited in  claim 12  wherein the cathodic/anodic pulse length ratio is from 1.1 to 2.7.