BAF TYPE COLD ROLLED STEEL PLATE HAVING GOOD SURFACE QUALITY AND GOOD FORMABILITY AND METHOD FOR MANUFACTURING THE SAME

摘要

PURPOSE: A BAF-type cold-rolled steel plate with excellent surface quality and formability and a method of manufacturing the same are provided to ensure excellent surface quality due to a small amount of C in an annealing process after cold rolling. CONSTITUTION: A BAF-type cold-rolled steel plate with excellent surface quality comprises carbon of 0.001~0.005 weight%, sulfur of 0.005~0.010 weight%, aluminum of 0.01~0.10 weight%, manganese of 0.01~0.10 weight%, nitrogen of 0.004 or less weight%, phosphorus of 0.015 or less weight%, titanium of 0.02~0.06 weight%, Fe and other inevitable impurities. The content of carbon in the steel plate is 50ppm or less. The steel plate is hot rolled and then TiC precipitate and AIN precipitate are formed. The average size of the AIN precipitate and TiC precipitate is 0.2m or less. The steel plate is hot rolled, and then is cooled to 650~800C at a cooling speed of 20~50C/sec.