LOW CONTAMINATION HIGH SPEED PICKLING METHOD

摘要

PURPOSE: A low contamination high speed pickling method is provided which is capable of pickling the hot rolled steel sheet with a pickling solution containing low concentrated hydrochloric acid or low concentrated sodium chloride at a low temperature for a short period of time by passing a hot rolled steel sheet through electrochemical treatment process. CONSTITUTION: In pickling a hot rolled steel sheet onto the oxide scale of which cracking is mechanically applied, the low contamination high speed pickling method comprises the processes of charging the steel sheet into an electrolytic cell which is filled up with an HCl solution having a concentration of 0.5 to 5%; and pickling the steel sheet by applying a cathode to the electrolytic cell and impressing a current density of 0.2 to 1.0 A/cm¬2 to the steel sheet at a solution temperature ranging from the room temperature to 80 deg.C for 40 seconds or less, wherein a current density of 0.6 to 1.0 A/cm¬2 is impressed at a solution temperature of 50 to 80 deg.C in case that the concentration of HCl is 0.5%, a current density of 0.2 to 1.0 A/cm¬2 is impressed at a solution temperature of 50 to 80 deg.C in case that the concentration of HCl is 1%, a current density of 0.2 to 1.0 A/cm¬2 is impressed at a solution temperature of 30 to 80 deg.C in case that the concentration of HCl is 2 to 5%, and a mixed pickling solution in which the above HCl is mixed with NaCl having a concentration of 2 to 10% is used as a pickling solution.