| 摘要 |
PROBLEM TO BE SOLVED: To provide a non-heat treated thick steel plate in which an as-rolled steel structure can be highly bainitized by the increase of solid-solution Ti and which has excellent weldability, such as prevention of softening of HAZ (heat-affected zone) at large heat input welding, and also has high toughness and high tensile strength. SOLUTION: The thick steel plate has a composition consisting of 0.01 to 0.10% C,≤1% (not including 0%) Si, 1.1 to 2.5% Mn,≤0.1% (not including 0%) Al, 0.05 to 1.0% Mo, >0.03 to 0.060% Ti, 0.0005 to 0.0050% B, 0.0020 to 0.0080% N,≤0.02% (not including 0%) P,≤0.01% (not including 0%) S and the balance Fe with inevitable impurities and also has a structure in which the amount of solid-solution Ti exceeds 0.03% and the fraction of bainite structure is controlled to≥90%. COPYRIGHT: (C)2006,JPO&NCIPI
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