| 摘要 |
This high-strength thick steel plate has a component composition in which the carbon equivalent (Ceq) is 0.3-0.5% and has a microstructure containing 70% or less of ferrite by area ratio and 30% or more of bainite by area ratio. At 1/4 of the plate thickness, the crystal grain boundary density, which is the total length per unit area of crystal grain boundaries having a crystal orientation difference of 15° or greater, is 400-1000 mm/mm2; and the area ratio of the {100} plane, which forms an angle within 15° with respect to a plane that is perpendicular to the main rolling direction, is 10-40%. At 1/2 of the plate thickness, the crystal grain boundary density is 300-900 mm/mm2; and the area ratio of the {110} plane, which forms an angle within 15° with respect to a plane that is perpendicular to the main rolling direction, is 40-70%. |
