High-tenacity steel plate for oceengineering and manufacturing method thereof

A high-toughness marine engineering steel sheet and a manufacturing method, out belongs to the field of marine engineering steel. Weight percent chemical composition: C 0.03-0.08%, Si 0.10-0.30%, Mn 1.0-1.60%, Alt 0.03-0.04%, Nb 0.03-0.06%, V 0.05-0.09%, Ti 0.010-0.02%, Mo 0.1 -0.4%, Ni 0.1-0.4%, Cu 0.1-0.4%, P <0.01%, S <0.005%, Nb + V + Ti≤0.12%, the balance being Fe and unavoidable impurities. By adding a small amount of Ni, and with a reasonable controlled rolling and cooling processes, to ensure the low temperature toughness of the steel sheet, heat treatment process is omitted, reduce production costs, resulting 10-50mm steel sheet has good strength and ductility, weldability, resistance to tearing and lamellar drop hammer excellent mechanical properties and the like; and the process is simple, can be widely used fixed, the key parts and semi-submersible jack-up offshore platform.