| 摘要 |
PURPOSE:To obtain the titled molten salt bath for modification enabling the removal of oxide scale on high Cr steel or the like by pickling in an improved state by adding KMnO4 or NaMnO4 to an NaOH-base molten salt bath contg. NaNO3 or KNO3. CONSTITUTION:Oxide scale which is difficult to remove on high Cr stainless steel, heat resistant steel or the like is modified by immersing the steel in a molten salt bath for pickling consisting of 5-40% NaNO3 and/or KNO3, 0.5-10% KMnO4 and/or NaMnO4, and the balance NaOH with impurities. The modified oxide scale is uniformly removed by the following pickling in a short time without causing surface roughening, and reduction of the thickness of the steel due to the pickling can be minimized. By adding KMnO4 and/or NaMnO4, the oxidizing power of the bath is increased to oxidize acid-insoluble oxide scale such as Cr2O3 to acid-soluble CrO3. |
