HIGH-STRENGTH COLD-ROLLED STEEL SHEET WITH EXCELLENT LOCAL FORMABILITY, AND MANUFACTURING METHOD THEREFOR

摘要

This high-strength cold-rolled steel sheet with excellent local formability contains, in mass%, 0.07% to 0.20% C, 0.001% to 2.5% Si, 0.01% to 4.0% Mn, 0.001% to 0.15% P, 0.0005% to 0.03% S, 0.001% to 2.0% Al, 0.0005% to 0.01% N, and 0.0005% to 0.01% O, with the remainder comprising iron and unavoidable purities; the area ratio of bainite in the metal structure is at least 95%; the average value of the polarization density of {100}<011> to {223}<110> orientation groups in a sheet thickness central area, which has a sheet thickness ranging from 5/8 to 3/8 from the surface of the steel sheet, is not more than 4.0, and the polarization density of the {332}<113> crystal orientation is not more than 5.0; and the volume mean diameter of the crystal particles of the metal structure is not more than 10 µm.