THICK PLATE FOR HIGH HEAT-INPUT WELDING EXCELLENT IN BRITTLE CRACK ARRESTIBILITY

摘要

A steel plate is provided which still exhibits excellent HAZ toughness and remarkable brittle cracking propagation cessation characteristic even under high thermal input welding. The inventive thick steel plate is formed by properly regulating chemical ingredients and meets the thick steel plates of the following formulae (1) and (2), and includes an organization having an organization with more than 95 area % of bainite fraction, and dislocation density of the bainite (rho1/2) is 1.0X106 to 5.0X107 (m-1). [Ti]/[N] is not less than 1.5 but not more than 4.0 ... (1), X value is not less than 40 but not more than 160 ... (2), X value = 500[C]+32[Si]+8[Mn]-9[Nb]+14[Cu]+17[Ni]-5[Cr]- 25[Mo]-34[V], in the formula, [] represents contents of each element (mass%).