Brief introduction of pickling electrolysis for packaging steel strip

Brief introduction of pickling electrolysis for packaging steel strip
　　The electrolysis method uses diluted acid, lye or neutral salt as the electrolyte. The electric current ensures that the chemical action of the electrolyte is realized and accelerates the electrochemical action process. There are three electrolysis methods: one is pickling the strip itself as a cathode or anode; the other is alternating strip polarity; the third is an intermediate conductor method, that is, when there is no contact with the strip, the current is transmitted through the electrode. The electrolyte reaches the strip, then through the strip, and then through the electrolyte to the opposite electrode. Cathode method, a large amount of hydrogen generated at the cathode, through pure mechanical action to loosen and fall off the oxide scale, the removal of the iron scale is fast, but a large amount of precipitated hydrogen can diffuse into the metal to cause hydrogen embrittlement; anode method, oxygen generated on the strip steel , It also makes the iron skin loose and fall off, but the oxygen precipitated in the same current and the same time is less than the hydrogen precipitated by the cathode method, so the removal speed of the iron skin is slower than that of the cathode method. In addition, although there is no hydrogen embrittlement problem, the precipitated oxygen promotes the metal surface Oxidation. In view of the advantages and disadvantages of the cathode method and the anode method, the intermediate conductor method is now mostly used in production.
　　Stainless steel electrolytic descaling can be carried out in molten sodium hydroxide melt, and the melt temperature is kept at about 430℃. Sodium hydroxide has the highest conductivity among all alkalis and is a good electrolyte for stainless steel. Some use acidic electrolyte, such as austenitic stainless steel, which is pre-descaled by shot peening, and then pickled in a mixture of 12-16% nitric acid and 3-5% hydrofluoric acid. % Sulfuric acid or nitric acid, the temperature is 50-70℃ electrolytic pickling tank, then enter the acid tank for secondary pickling. Ferritic stainless steel is first electrolytically pre-descaled with 5% sulfuric acid, and then electrolytically pickled with dilute nitric acid for the second time.
　　The electrolytic pickling time is short, the effect is good, but the cost is high, and it is mainly used for high-grade alloy steel.