MANUFACTURING METHOD OF HIGH CLEANNESS AND FULL HARDENING COLD ROLLED STEEL SHEET

摘要

PURPOSE: Provided is a method for manufacturing a high cleanness and full hardening cold rolled steel sheet, where coil, after passing through electrolytic degreasing line, is heated under initial recrystallization temperature via continuous annealing line to confirm cleanness of cold rolled steel sheet without deteriorating hardness of the cold rolled steel sheet. CONSTITUTION: In the manufacturing method of high cleanness and full hardening cold rolled steel sheet, the method includes: (i) descaling a hot coil followed by continuous cold rolling; (ii) electrolytic-degreasing the cold rolled steel sheet; and (iii) passing the cold rolled steel sheet through continuous annealing line at a temperature lower than initial recrystallization temperature(520deg.C). In the third step, dummy material is inputted right after cold rolling to prevent sudden roll crown in the annealing furnace.