| 摘要 |
The present invention provides a steel sheet that contains prescribed steel sheet components, B is restricted to less than 0.0003%, and the remainder comprises Fe and unavoidable impurities. The steel sheet contains Ti, Nb and Mo in a range in which the quantity of Ti ([Ti]), the quantity of Nb ([Nb]) and the quantity of Mo ([Mo]) satisfies the relationship ([Nb])/([Ti]) + ([Nb]) + ([Mo]) ≥ 0.3, and precipitates have an average particle size of 20 nm or less. A thick steel sheet with high tensile strength can thus be obtained, said steel sheet: being suitable for use in steel structures such as marine structures, ships, pressure vessels and penstocks; having a yield stress (YS) of at least 460 MPa; and having excellent low-temperature toughness (CTOD characteristics) in multilayer weld zones affected by weld heat and strength and toughness(PWHT characteristics) after being heat treated during welding. |
