Are superior in waterproof element embrittlement characteristic and ductility the high intensity structural steel and the production

摘要

PROBLEM TO BE SOLVED: To provide a high strength structural steel having such satisfactory hydrogen embrittlement resistance, toughness and ductility that it can be generally used as a high strength structural steel required to have a tensile strength of ≥1,250 MPa, and to provide a production method by which this high strength structural steel can be relatively easily produced.;SOLUTION: This high strength structural steel comprises, by weight, 0.35-0.65% C, ≤3.0% Si, 0.10-0.70% Mn, 0-3.0% Ni, 0.1-1.9% Mo, 0-2.0 Cr, 0-0.1 Nb, ≤0.025% S, ≤0.025% P, ≤0.040% Al, ≤0.0035% N, ≤0.0040% O, and the balance Fe with inevitable impurities, and has an average grain diameter of a prior austenite of ≤5.5 μm, a maximum diameter of non-metallic inclusion of ≤5 μm, a tensile strength of ≥1,250 MPa and a yield ratio of ≥0.95.;COPYRIGHT: (C)2008,JPO&INPIT