Hydrogen peroxide pickling of stainless steel

A process for removing scale from steel, comprising:

• providing a stainless steel strip covered by a scale,
• pretreating the strip to crack the scale,
• immersing the treated strip into a first tank containing sulfuric acid or hydrochloric acid to remove the cracked scale thereby forming a pickled strip,
• applying a solution free of dissolved iron and containing at least 5 g/l of the acid, and at least 10 g/l hydrogen peroxide to the pickled strip wherein any remaining scale on the pickled strip becomes activated by the peroxide,
• immersing the activated strip into a second tank containing hydrochloric acid to remove any residual scale, and
• recycling the aqueous solution to one of the tanks.

A process for removing scale from steel, comprising:

• providing a ferritic stainless steel strip covered by a scale,
• pretreating the strip to crack the scale,
• immersing the treated strip into a first tank containing at least 150 g/l sulfuric acid to remove the cracked scale thereby forming a pickled strip,
• applying a solution free of dissolved iron and containing at least 10 g/l of the acid, and at least 20 g/l hydrogen peroxide to the pickled strip wherein any remaining scale on the pickled strip becomes activated by the peroxide,
• immersing the activated strip into a second tank containing at least 50 g/l hydrochloric acid to remove any residual scale,
• recycling the aqueous solution to the sulfuric acid, and brushing the pickled strip to loosen any residual scale not removed by the acid.