Low-cost 960MPa-grade ultrahigh-toughness steel plate and preparation method thereof

The invention discloses a preparation method of a low-cost 960MPa-grade ultrahigh-toughness steel plate, and belongs to the field of steel rolling and heat treatment. The steel plate is prepared from, by mass, 0.18%-0.25% of C, 1.6%-1.8% of Mn, 0.5%-0.6% of Cr, 0.04%-0.06% of V, 0.01%-0.02% of Ti, 0.001%-0.002% of B and the balance Fe and inevitable impurities. A heat treatment process of quenching and medium-temperature tempering is adopted in the heat treatment procedure of the steel plate, specifically, quenching is conducted at the temperature of 880-920 DEG C, heat preservation is conducted for 10-20 min, medium-temperature tempering is conducted, the tempering temperature is 450-520 DEG C, and heat preservation is conducted within 45 min. The manufactured steel plate has high strength and high toughness, the yield strength is larger than or equal to 960 MPa, the tensile strength is larger than or equal to 1050 MPa, and the ductility is larger than or equal to 15%; the impact energy at-40 DEG C is not le