| 摘要 |
PURPOSE:To efficiently descale a cold rolled and annealed stainless steel strip in a short time, by successively subjecting the strip to electrolysis in an aq. sulfuric acid soln. having a high concn. and to electrolysis in a chloride added aq. nitric acid soln. CONSTITUTION:A cold rolled and annealed stainless steel strip is subjected to electrolysis in an aq. sulfuric acid soln. having a high concn. of 900-1,250g/l, especially 1,000-1,200g/l at 40-85 deg.C and >=2.5A/dm<2> current density. The strip is then subjected to electrolysis in an aq. nitric acid soln. contg. a chloride such as HCl or FeCl3 added by 0.3-10g/l (expressed in terms of chlorine equiv.) to carry out descaling. The desirable concn. of the nitric acid soln. is about 50-200g/l and the pref. temp. is about 40-60 deg.C. Since this descaling method makes pretreatment such as salt treatment unnecessary, the stages can be simplified. The descaling time is shortened, high-speed passing through is enabled and the productivity is improved.
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