| 摘要 |
PROBLEM TO BE SOLVED: To produce an extremely thick and high tensile strength steel used as a steel for large wlding structures and to provide a method for producing the same. SOLUTION: This steel contains mainly, by weight, 0.07 to 0.2% C, 0.05 to 0.5% Si, 0.6 to 1.5% Mn, 0.1 to 1% Cu, 1 to 5% Ni, 0.01 to 0.05% Nb, 0.01 to 0.1% sol.Al, 0.0003 to 0.003% B, <=0.006% N, and the balance Fe with inevitable impurities. Then, at least in the center part of the steel plate, the B segregation parameter consisting of the austenite average grain size (d) (μm) and the austenite grain size distribution dispersionΔd, i.e., BSP =(10,00×[B]-0.4×d)×([Al]/2[N]×(d/Δd) satisfies 100<=BSP<=300 and, >=950N/mm<2> tensile strength is satisfied.
|
