Continuous casting slab for high-strength steel, and steel plate obtained from the slab

摘要

PROBLEM TO BE SOLVED: To provide a continuously cast slab which can be used as a stock for a steel sheet in which a stripe pattern on the surface is hardly caused upon bending, and a continuous casting method therefor.;SOLUTION: (1) The continuously cast slab for a high strength steel sheet has a composition containing, by mass, 0.03 to 0.20% C, 0.005 to 2.0% Si, 1.2 to 3.5% Mn, ≤0.1% P, ≤0.01% S, ≤0.01% N, 0.001 to 1.0% Al and 0.0001 to 0.05% Bi, and the balance Fe with impurities, and in which the spacing of the primary arms of dendrite within the range from the surface layer of the continuously cast slab to 10 mm is ≤300 μm, and the ratio between the Mn content between the trees of the primary arms of the dendrite and the average Mn content of the cast slab is ≤2.5. (2) A Bi-containing metal wire is inserted into an immersion lance immersed into molten steel, thus metal vapor is generated within the immersion lance, and is fed into the molten steel together with a carrier gas.;COPYRIGHT: (C)2011,JPO&INPIT