Excellent processability BHI cold-rolled steel sheet and a method of manufacturing the same

摘要

PURPOSE: A method of manufacturing a BH(baked hardening) cold-rolled steel plate is provided to reduce costs by omitting an RH process for a long time and to enhance processability by reducing irregularity of products. CONSTITUTION: A BH cold-rolled steel plate consists of, by weight %: 0.010-0.050% of C, not more than 0.010% of Mn, 0.002-0.030% of Zr, not more than 0.020% of P, not more than 0.015% of S, not more than 0.015% of Si, 0.02-0.05% of Al, not more than 0.004% of N, Fe and incidental impurities. The steel plate is heated at a temperature of 1100-1300°C and coiled at a temperature of 650-750°C. After that, the steel plate is cold-rolled to 65-80% and continuously annealed at a temperature of 750-850°C and of 350-450°C. The BH cold-rolled steel plate is manufactured by rolling the annealed steel plate to 1.0-2.0%.