| 摘要 |
PROBLEM TO BE SOLVED: To provide a high-strength thick steel plate having excellent brittle crack propagation-stopping performance, and to provide a method for producing the same. SOLUTION: The high-strength thick steel plate contains as chemical components, by mass, 0.04 to 0.15% C, 0.1 to 0.5% Si, 0.5 to 2.5% Mn,≤0.02% P,≤0.01% S, 0.001 to 0.1% Al, 0.003 to 0.05% Nb, 0.005 to 0.02% Ti and 0.001 to 0.008% N, and the balance iron with inevitable impurities, and the microstructure is a ferrite or/and pearlite structure where bainite is used as a host phase. In the case the structure is divided into the three layers in a sheet thickness central part region around the sheet thickness central part of the steel sheet, and front-rear layer part regions other than that, a texture where the (111) or/and (211) X-ray face intensity ratio parallel to the rolling face is 1.5 to <2.0 is included in the central part region of 10 to <50% of the sheet thickness, and a texture where the (100) X-ray face intensity ratio parallel to the rolling face is≥2.0 is included in the front-rear layer part regions other than that. COPYRIGHT: (C)2008,JPO&INPIT
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