| 摘要 |
A high strength steel plate obtained from, in mass%, the chemical components of C: 0.20-0.42%, Si: 0.06-0.5%, Mn: 0.2-2.2%, Cr: 0.1-2.5%, B: 0.0005-0.01%, O: 0.0020-0.020%, Al: 0.001-0.03%, Ti: 0.001-0.05%, N: 0.1% or less, P: 0.03% or less, and S: 0.02 or less, with the remainder being Fe and unavoidable impurities. In the steel, 5 × 103/mm2 to 1 × 105/mm2 of Mn oxide with a maximum length of 1 µm to 5 µm are present and 1.7 × 102/mm2 to 5 × 103/mm2 of complex oxides of Mn and Si with short axial direction lengths of 1 µm or more and long axial direction lengths of 10 µm or less are present. |
