| 摘要 |
The present invention relates to a steel for a welded structure with excellent HAZ toughness, containing, in terms of wt%, C: 0.01 to 0.2%, Si: 0.02 to 0.5%, Mn: 0.3 to 2%, P: 0.03% or less, S: 0.0001 to 0.03%, Al: 0.0005 to 0.05%, Ti: 0.003 to 0.05%, Mg: 0.0001 to 0.01% and 0: 0.0001 to 0.008%, with the balance consisting of Fe and unavoidable impurities; and having particles dispersed in the steel at an average particle interval of 30 to 100 mu m, the particles being formed by precipitating either any one of sulfides and nitrides singly or the both thereof in combination using Mg contained oxides with the particle sizes of 0.2 to 5 mu m as their nuclei, or particles dispersed in the steel at an average particle interval of 30 mu m or less, the particles being formed by precipitating either any one of sulfides and nitrides singly or the both thereof in combination using Mg contained oxides with the particle sizes of 0.005 to less than 0.2 mu m as their nuclei. <IMAGE> |
