The invention relates to a large-thickness high-performance SA302GrC steel plate and a production method thereof, belonging to the technical field of steel
smelting processes. According to the technical scheme, the production method comprises procedures of
smelting,
casting, heating, rolling, cooling after rolling, normalizing, accelerated cooling and
tempering; and the steel plate is prepared from the following
chemical ingredients in percentage by
mass: 0.10-0.18% of C, 0.15-0.40% of Si, 1.20-1.45% of Mn, less than or equal to 0.015% of P, less than or equal to 0.010% of S, 0.40-0.55% of Ni, 0.45-0.60% of Mo, and the balance of Fe and inevitable impurities. The steel plate has the following advantages that the obdurability matching is good, the yield strength Re is greater than or equal to 345Mpa, the transverse Charpy
impact in the position which is 1 / 4 of the plate thickness at minus 10 DEG C is less than 41J, the
steel quality is purer, the lamellar tearing resisting property is good, the through thickness direction Z is greater than or equal to 35%, the
welding property is good, and the thickness of the steel plate is 135mm. The steel plate which is produced by using the production method provided by the invention has the characteristics of high purity, uniformity in component and internal compactness, and has good obdurability matching.