Q420-grade improved high-toughness corrosion-resistant steel plate as well as production method and application thereof

The invention discloses a Q420-grade improved corrosion-resisting steel plate with high toughness and a production method and application thereof. The steel plate comprises the following chemical components in percentage by weight: 0.06%-0.08% of C, 0.15%-0.40% of Si, 1.05%-1.25% of Mn, less than or equal to 0.020% of P, less than or equal to 0.003% of S, 0.01%-0.02% of Nb, 0.01%-0.02% of Ti, 0.02%-0.05% of Als, 0.30%-0.70% of Cu, 0.7%-1.5% of Ni, 0.08%-0.30% of Sb and the balance of Fe and inevitable impurity elements. In the process steps, through an in-situ analysis technology, process parameters are improved, specific design of components is matched, the core quality of the steel plate is improved, and the statistical segregation degree of C, Mn, Ni, Cu and Sb is smaller than or equal to 0.05. The thickness specification is smaller than or equal to 100 mm, the yield strength is larger than or equal to 420 MPa, the tensile strength is larger than or equal to 540 MPa, the impact toughness KV2 at the low tem