| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for effectively removing a scale, without conducting mechanical preliminary descaling such as shot blasting or brush grinding before pickling, when removing an oxidized scale generating in a hot rolling or heat treating process of a stainless steel. SOLUTION: The pickling method for removing the oxidized scale generating on the surface of the stainless steel, comprises sequentially dipping the stainless steel into a hydrochloric acid solution of 100 g/L or higher in the first pickling tank, an acid solution including fluoric acid of 10 g/L or higher in the second pickling tank, a hydrochloric acid solution of 100 g/L or higher in the third pickling tank, and an acid solution including fluoric acid of 10 g/L or higher in the fourth pickling tank. As required, a compound containing a sulfhydryl group of 0.001 mol/L or more, or amine of 0.001 mol/L or more, can be added into the hydrochloric acid bath; concentration of the fluoric acid bath can be 15-100 g /L for fluoric acid and 50-250 g/L for nitric acid; and chloride ions of 0.1 g/L or more with hydrochloric acid and/or thiocyanate ions of 0.17 g/L or more can be added.
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