HIGH STRENGTH THICK STEEL PLATE EXCELLENT IN TOUGHNESS OF HIGH HEAT INPUT WELDING PART AND BRITTLE CRACK PROPAGATION STOPPING PROPERTY, AND METHOD FOR PRODUCING THE SAME

摘要

PROBLEM TO BE SOLVED: To provide a steel plate excellent in toughness of a high heat input welding part and brittle crack propagation stopping properties, and to provide a method for producing the steel plate.;SOLUTION: A high strength thick steel plate includes specific contents of C, Si, Mn, Al, P, S, Nb, Ti, N, Ca and B, wherein 0(Ca-(0.18+130×Ca)×O)/1.25/S1 and Ceq(=C+Mn/6+(Cu+Ni)/15+(V+Mo+Cr)/5) is ≥0.36% and 0.45%, and one or more kinds of Cu, Ni, Cr, Mo and V, as occasion demands, with the remainder comprising Fe and inevitable impurities. The high strength steel plate has such a texture that the X-ray intensity ratio of (211) plane in a plane parallel to the steel plate surface is ≥1.0, in a region of ≥1/3 of the whole plate thickness including the central part of the plate thickness, and has a bainite fraction of ≥80% in the central part of the plate thickness and a Charpy fracture surface transition temperature of ≤-40°C in a part of 1/4 of the plate thickness.;COPYRIGHT: (C)2013,JPO&INPIT