High-strength thick steel plate for construction having excellent characteristics for preventing diffusion of brittle cracks, and production method therefor

Abstract

Provided are: a high-strength thick steel plate for construction having excellent characteristics for preventing the diffusion of brittle cracks, 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, characterized in that: the thick steel sheet has a specific component composition; the main constituent of the metal structure is a ferrite phase; the thick metal sheet has an aggregate structure in which the density (I) in the RD / / (110) plane at the plate thickness surface is at least 1.3, and the density (I) in the RD / / (110) plane at the plate thickness center is at least 1.8; the Charpy fracture appearance transition temperature (vTrs) at the surface is not more than -60 DEG C, and the Charpy fracture appearance transition temperature (vTrs) at the plate thickness center is not more than -50 DEG C.

Description

technical field [0001] The present invention relates to a high-strength thick steel plate for structural use excellent in brittle crack arrestability (brittle crack arrestability) and a manufacturing method thereof, and particularly relates to a plate with a thickness of 50 mm or more suitable for ships high-strength thick steel plate. Background technique [0002] For large structures such as ships, accidents caused by brittle fractures have a great impact on the economy and the environment. Therefore, it is generally required to improve safety, and toughness at operating temperatures is required for the steel materials used (toughness), and brittle crack propagation stop characteristics. [0003] Vessels such as container ships and bulk carriers use high-strength thick-walled materials for outer plate of ship's hull in their structures. Recently, along with the increase in the size of the hull, high-strength and thicker walls are further developed. In general, the britt...

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Problems solved by technology

[0011] However, the steel materials with excellent brittle crack propagation arresting properties described in Patent Documents 1 and 2 obtained a specific structure by cooling only the surface layer of the steel material and then reheating, and performing processing during the reheating. It is difficult to control, especially for thick-walled materials with a plate thickness exceeding 50mm, it is a process that places a large load on rolling and cooling equipment

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