| 摘要 |
PURPOSE:To obtain a deep drawing cold rolled steel plate excellent in quality uniformity and chemical forming treatment properties, by a method wherein steel prepared by compositely adding Ti and Nb to extremely low C steel under a specific condition is hot rolled at a proper temp. and, after winding, treated steel is descaled, cold rolled and subjected to recrystallization annealing. CONSTITUTION:Ti and Nb are compositely added to steel consisting of 0.007% or less C, 0.8% or less Si, 1.0% or less Mn, 0.15% or less P, 0.01-0.1% Al, 0.008% or less N and the remainder of Fe and inevitable impurities. Ti is contained within a range satisfying a 48/14 (N%-0.002)<Ti%<4C%+3.43N% while Nb is contained so as to satisfy Nb%>2C% within a range of 0.003-0.025% and in such an amount that Nb+Ti does not exceed 0.04%. This steel slab is hot rolled and finish rolled at 720-870 deg.C while the rolled steel plate is wound up at 680 deg.C or less. Subsequently, this steel plate is subjected to descaling treatment, cold rolled and subsequently subjected to recrystallization annealing. By this method, a cold rolled steel plate having uniform material quality and excellent deep drawing properties is obtained. |
