| 摘要 |
PROBLEM TO BE SOLVED: To provide a thick steel plate having a high-strength level in an 490 MPa class particularly suitable for a vessel, and having excellent uniform elongation, and to provide a method for producing the thick steel plate. SOLUTION: The high-tensile strength thick steel plate is composed of a steel having chemical components comprising, by mass, 0.02 to 0.20% C, 0.2 to 0.5% Si, 1 to 1.8% Mn and Cu and/or Ni by 0.2 to 1% in total, and the balance Fe with inevitable impurities, and in which a ferrite fraction is≥80 vol.%, a retained austenite fraction is≥1 vol.%, and the C content in the retained austenite is 0.80 to 1.10 mass%. COPYRIGHT: (C)2008,JPO&INPIT
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