PRETREATMENT OF COLD ROLLED STEEL SHEET FOR ZINC-PHOSPHATE TREATMENT

摘要

PURPOSE: A method for activating the surface of cold rolled steel sheets for optimal zinc-phosphate treatment is provided. CONSTITUTION: For the improved zinc-phosphate treatment of cold rolled steel sheet for drums, total amount of residual Cu and Cr in steel is regulated lower than 1000ppm, and FCS(final cooling section) is below 110deg.C. Also, surface roughness(Ra) after temper rolling is in the range of 0.9 to 1.4 micrometer.