High toughness low carbon bainite thick steel plate and its production method

The invention offers a high tensile strength low carbon bainite coarse plate and its manufacturing method. Its compositions (Wt%) are C 0.04%-0.08%, Si 0.1%-0.5%, Mn 1.4%-1.85%, Nb 0.015%-0.060%, Ti 0.005%-0.03%, B 0.0005%-0.0030%, Cu 0.10%-0.60%, Ni 0.05%-0.6%, Al 0.015%-0.05%, rest Fe and other inevitable impurity. The invention adopts low cost Mn element as the main additional element, fully applies the changing action of Cu, Ni, Nb, B to the bainite. The steel has low carbon content, good low temperature toughness. The turning temperature is under ?C80 centigrade degree. Welding performance is good and simple. Forming is good. TMCP+RPC technique is adopted to improve steel tensile strength, reduced cost. The product can widely apply in engineering machinery, digging machinery, heavy-duty car, and marine facilities field, and etc.