Extra-thick low-alloy high-strength steel plate for ocean platform and production method thereof

The invention discloses a steel plate for an extra-thick low-alloy high-strength ocean platform and a production method of the steel plate. The steel plate comprises the following chemical components in percentage by mass: 0.09-0.13% of C, 0.20-0.40% of Si, 1.45-1.62% of Mn, 0.30-0.50% of Ni, 0.020-0.050% of Al, 0.010-0.020% of Ti, 0.020-0.035% of Nb, less than or equal to 0.010% of P, less than or equal to 0.003% of S, less than or equal to 0.43% of Ceq, less than or equal to 0.22% of Pcm and the balance of Fe and inevitable impurities. The production method comprises the procedures of smelting, continuous casting, heating and rolling. The steel plate provided by the invention has good comprehensive performance and welding performance, especially has excellent low-temperature strain aging impact toughness and low-strain aging sensitivity, can be widely applied to weldable structural steel of a fixed offshore structure, and has a wide application prospect. 本发明公开了一种特厚低合金高强海洋平台用钢板及其生产方法，其化学成分组成及质量百分含量为：C：0.09～0