The high intensity thick steel sheet and its production manner which for structure are superior in brittle crack propagation halt property

摘要

Provided are: a high-strength thick steel plate for construction having excellent characteristics for preventing the diffusion of brittle cracks and said plate being used for ships and having a preferred plate thickness of at least 50 mm; and a method for producing the thick steel plate. The thick steel plate has excellent characteristics for preventing the diffusion of brittle cracks and characterized in that: the main constituent of the metal structure is bainite; the steel plate has an aggregate structure in which the density (i) in the RD//(110) plane at the plate thickness center is at least 1.5; and the Charpy fracture appearance transition temperature (vTrs) at the surface and plate thickness center is not more than -40C. More preferably and the Charpy fracture appearance transition temperature (vTrs) at the plate thickness center and the density (i) in the RD//(110) plane satisfy formula (1). vTrs (1/2t) - 12 IRD//(110) [1/2t] = -70 (1), wherein and vTrs (1/2t) is the fracture appearance transition temperature at the plate thickness center (C), and IRD//(110) [1/2t] is the density in the RD//(110) plane at the plate thickness center.