HIGH-STRENGTH THICK STEEL PLATE EXCELLENT IN TOUGHNESS OF HIGH-HEAT-INPUT WELD ZONE AND IN PROPERTIES OF STOPPING PROPAGATION OF BRITTLE CRACK, AND METHOD FOR MANUFACTURING THE SAME

摘要

PROBLEM TO BE SOLVED: To provide a high-strength thick steel plate which is suitable for a thick steel plate with a plate thickness exceeding 50 mm and is excellent in the toughness of a high-heat-input weld zone and in properties of stopping the propagation of a brittle crack, and to provide a method for manufacturing the same.;SOLUTION: The steel plate includes, by mass%, 0.03 to 0.20% C, 1.0% or less Si, 1.0 to 2.0% Mn, 0.005 to 0.017% Al, P, S and Nb, 0.005 to 0.02% Ti, 0.0005 to 0.0030% N and Ca, 0.0005 to 0.0020% B, so that Ca, O and S satisfy the following expression: 0(Ca-(0.18+130×Ca)×O)/1.25/S1, wherein Ca, O and S represent the contents (mass%) of the respective components, and one or more elements selected from Cu, Ni, Cr, Mo and V, as needed; has a texture in which an X-ray intensity ratio in the (211) face on a rolled face in a central part of a plate thickness is 1.3 or more, and the X-ray intensity ratio in the (110) face on the rolled face in the 1/4 deep part of the plate thickness is 0.8 or more; and has a Charpy fractured-face transition temperature of -40°C or lower in the 1/4 deep part of the plate thickness.;COPYRIGHT: (C)2010,JPO&INPIT