HIGH-STRENGTH THIN STEEL SHEET SUPERIOR IN DELAYED FRACTURE RESISTANCE AFTER BEING FORMED, MANUFACTURING METHOD THEREFOR, AND HIGH STRENGTH COMPONENT FOR AUTOMOBILE MADE OF THE HIGH-STRENGTH THIN STEEL SHEET

摘要

PPROBLEM TO BE SOLVED: To provide a high-strength thin steel sheet which prevents hydrogen- attributed defects from occurring after being formed, and is superior in delayed fracture resistance, and to provide a manufacturing method therefor. PSOLUTION: The thin steel sheet includes 7% or less of retained austenite by volume fraction, 100-100,000 pieces per square meter of crystallites and precipitates with particle diameters of 0.01-5.0 m, and, by wt.%, 0.05-0.3% C, 3.0% or less Si, 0.01-3.0% Mn, 0.02% or less P, 0.02% or less S, 3.0% or less Al, 0.01% or less N, 0.0002-0.01% Mg, and the balance iron with unavoidable impurities. The thin steel sheet can further include Ti, Nb, V, Zr, Cr, Mo, W, Cu, Ni, Co, B, REM, Ca, and Y, as selective elements in the steel composition. PCOPYRIGHT: (C)2003,JPO