PRODUCTION OF COLD ROLLED STEEL STRIP HAVING GOOD SURFACE CHARACTERISTIC

摘要

PURPOSE:To decrease the thickness of the oxide film on a cold rolled steel strip and to improve the appearance and phosphate treatability of the strip by incorporating a water soluble metallic compd. into primary and secondary cooling water in the continuous heat treatment of the cold rolled steel strip at the time of producing the cold rolled steel strip by a continuous annealing method. CONSTITUTION:An aq. soln. contg. the water soluble metallic compd. or contg. an alpha-amino acid therein is used for the primary and secondary cooling water in the continuous heat treatment of the cold rolled steel strip having respective stages for a recrystallization heating treatment, primary cooling, overaging treatment and secondary cooling. Any of inorg. or org. compd. which is water soluble is usable as the metallic compd. to be used in this case. The surface cleanliness of the cold rolled steel strip is improved and the effective pretreatment for the phosphate treatment is executed by the above-mentioned method.