High-strength thick steel plate and a method of manufacturing the same for high heat input welding with excellent brittle crack propagation stop characteristics

摘要

Provided are a high strength thick steel plate, which has superior brittle crack arrestability for high heat input welding that has a plate thickness of 50 mm or greater and is suitably used in marine vessels, and a manufacturing method for the same. The present invention is a thick steel plate and a manufacturing method for the same, wherein the thick steel plate has: a specific component composition, a metal structure composed mainly of ferrite, and an aggregate structure in which the density at the RD//(110) plane at the surface layer of the plate thickness is 1.3 or greater and the density at the RD//(110) plane in the center part of the plate thickness is 1.8 or greater. Charpy fracture appearance transition temperature (vTrs) is −50°C or less at the surface layer and in the center part of the plate thickness.