High-strength hot-dip steel sheet and cold-rolled steel sheet with excellent continuous productivity, high-strength hot-dip galvanized steel sheet with excellent surface quality and plating adhesion, and their manufacturing methods

摘要

% By weight, C: 0.14 to 0.3%, Si: 1 to 2.0%, Mn: 2.6 to 5%, sol. Al: 0.001 to 2%, Ti: (48/14) * [N] to 0.1%, P: 0.04% or less (excluding 0%), S: 0.015% or less (0% , N: 0.02% or less (except 0%), one or more of Sb, Bi, Sn, and Zn: 0.08 to 0.2% in total, hot rolled with the balance Fe and unavoidable impurities In a steel sheet, an internal oxide containing at least one of Si, Mn, Al, and Fe is present in a surface layer portion of the hot-rolled steel sheet, and a maximum depth of the internal oxide is 1 μm or less. (Including 0 μm).