Low-alloy high-strength high-hardness martensite protective steel with hardness of 500 HBW grade and manufacturing method thereof

The invention belongs to the field of armored protective steel, and provides low-alloy high-strength high-hardness martensite protective steel with the hardness of 500 HBW grade and a manufacturing method thereof, and the low-alloy high-strength high-hardness martensite protective steel comprises the following chemical components in percentage by weight: 0.22 to 0.32 percent of C, 0.2 to 0.6 percent of Si, 0.28 to 1.20 percent of Mn, less than or equal to 0.015 percent of P, less than or equal to 0.003 percent of S, 0.4 to 0.7 percent of Cr, 0.6 to 1.5 percent of Ni, 0.3 to 0.7 percent of Mo, 0.001 to 0.005 percent of B, 0.02 to 0.06 percent of Al, 0.01 to 0.025 percent of Ti, 0.01 to 0.03 percent of Nb and the balance of Fe and inevitable impurities. The martensite volume fraction of the steel plate is larger than 90%, and the steel plate has high strength, high hardness and good plasticity and toughness and is suitable for manufacturing bulletproof vehicles, bulletproof tools and key parts of military armor