LARGE-THICKNESS LAMELLAR TEARING-RESISTANT HIGH-STRENGTH STEEL PLATE WITH 960 MPA-LEVEL YIELD STRENGTH, AND PRODUCTION METHOD THEREFOR

The invention relates to a large thickness high-strength steel plate with a lamellar tear resistance yield strength of 960MPa-level and a production method thereof. The chemical composition comprises (wt% in weight): C: 0.15 - 0.20%, Si: 0.10 - 0.40%, Mn: 0.90 - 1.30%, Nb: 0.010 - 0.040%, V: 0.010 - 0.045%, Ti: ≤ 0.010%, Al: 0.03 - 0.06%, Ni: 0.50 - 1.00%, Cu: ≤ 0.1%, Cr: 0.30 - 0.80%, Mo: 0.20 - 0.70%, B: 0.001 - 0.005%, Ca: 0.001 - 0.005%, P: ≤ 0.010%, S: ≤ 0.002%, O: ≤ 0.002%, N: ≤ 0.004%, H: ≤ 0.00015%, the balance is Fe and inevitable impurity elements; Carbon equivalent CEV: 0.58 - 0.68%. The process steps are: smelting - > refining outside the furnace - > vacuum degassing - > Ca Treatment - > continuous casting - > heating - > rolling - > slow cooling of steel plate - > quenching - > tempering. The steel plate of the invention has a thickness of 50 - 100mm, has excellent comprehensive mechanical properties, yield strength ≥ 960MPa, tensile strength ≥ 1000MPa, low-temperature Charpy impact energy at - 40°C ≥ 30J, tensile section shrinkage in Z direction ≥ 35%, and has good lamellar tear resistance, which meets the application requirements of large thickness ultra-high strength steel plate in large machinery industry.