Excellent steel plate and a method of manufacturing the same in crack growth resistance-out resistance to fatigue

摘要

PPROBLEM TO BE SOLVED: To provide a steel sheet excellent in fatigue crack resisting performance, having enhanced resistance to propagation of cracks inherent in a weld zone of a welded structure or the like, the propagation occurring caused by repeated stress applied to the cracks, and to provide a production method thereof. PSOLUTION: The steel sheet for a marine structure is provided which has a chemical composition comprising, by mass, 0.01 to 0.1% C, 0.03 to 0.6% Si, 0.3 to 2% Mn, 0.001 to 0.1% sol.Al, 0.0005 to 0.008% N, and the balance Fe with impurities, and also has a metallic structure composed of a bainitic structure of 60 to 85% by area ratio, a martensitic structure and a pearlitic structure of 0 to 5% in total, and the balance ferritic structure, wherein the impact absorption energy vE-20 in a Charpy impact test is ≥387 J, and a production method thereof is also provided. PCOPYRIGHT: (C)2010,JPO&INPIT