Special steel for composite reinforced protection and manufacturing method thereof

The invention relates to special steel for composite reinforced protection and a manufacturing method thereof, and belongs to the technical field of production of high-strength quenched and tempered steel plates. The special steel is composed of, by weight, 0.27%-0.35% of C, 0.30%-0.45% of Si, 0.35%-0.75% of Mn, smaller than or equal to 0.010% of P, smaller than or equal to 0.008% of S, 0.60%-1.60% of Cr, 0.40%-1.00% of Ni, 0.40%-0.80% of Mo, 0.030%-0.060% of V, 0.015%-0.035% of Ti, 0.010%-0.030% of RE, 0.025%-0.045% of Alt, 0.0018%-0.0026% of B, smaller than or equal to 20 ppm of [O], smaller than or equal to 20 ppm of [N], smaller than or equal to 2 ppm of [H] and the balance Fe and inevitable impurities. Compared with the prior art, a certain amount of rare earth elements are added to a Cr-Ni-Mo component system, the overall adding amount of Cr, Ni, Mn, Mo, V, Ti and other alloy elements can be reduced, meanwhile, it can be guaranteed that the performance is not lower than that of products of the same grad