At the direct hardening die high tension thick steel sheet null not yet recrystallization

摘要

PROBLEM TO BE SOLVED: To provide a high tensile strength thick steel plate which has a tensile strength of a class of 950 N/mm² and is used for a welded structure for brittle, crack propagation prevention of the steel sheet.;SOLUTION: The direct-quenched high tensile strength thick steel plate having excellent arrest properties has a composition containing, by weight, 0.07 to 0.2% C, 0.01 to 0.30% Si, 0.4 to 1.5% Mn, 1 to 3.5% Ni, 0.1 to 1% Cr, 0.1 to 1% Mo, 0.01 to 0.10% V, 0.01 to 0.10% Al, 0.0003 to 0.0030% B, and 0.0010 to 0.0070% N. Its tensile strength in the 1/4 t part in the rolling direction is higher than that in the 1/2 t part in the rolling direction by ≥(0.5 t) MPa, and in the tensile strength of four kinds in the 1/4 t parts and the 1/2 t parts in the rolling direction and the plate width direction, that in the 1/4 t part in the rolling direction is the highest.;COPYRIGHT: (C)2003,JPO