High-strength high-toughness low-temperature maritime work steel plate and manufacturing method thereof

The invention provides a high-strength high-toughness low-temperature maritime work steel plate and a manufacturing method. The steel plate comprises the following components in percentage by weight: 0.085%-0.13% of C, 0.16%-0.4% of Si, 0.8%-1.4% of Mn, less than or equal to 0.02% of P, less than or equal to 0.01% of S, 0.02%-0.04% of Als, 3.2%-4.5% of Ni, 0.3%-0.7% of Cr, 0.3%-0.6% of Mo, 0.4%-0.7% of Cu, 0.01%-0.04% of Nb, 0.1%-0.25% of V, 0.003%-0.006% of N and the balance of Fe and inevitable impurities. The production method of the steel plate comprises the steps of smelting, casting, low-temperature heating, controlled rolling, controlled cooling and low-temperature tempering. The yield strength of the maritime work steel plate is larger than or equal to 690 MPa, the tensile strength is 770-940 MPa, the ductility is larger than or equal to 16%, the Charpy impact energy at-80 DEG C is larger than or equal to 70 J, and the thickness is smaller than or equal to 60 mm. 本发明提出一种高强度高韧性低温海工钢板及制造方法，钢板成分按重量百分比计：C