SA516Gr70 steel plate with excellent high-temperature strength higher than 400-525 DEG C and manufacturing method of SA516Gr70 steel plate

The invention relates to an SA516Gr70 steel plate with excellent high-temperature strength higher than 400-525 DEG C and a manufacturing method of the SA516Gr70 steel plate, and belongs to the field of steel plate metallurgy. The steel comprises the following chemical components in percentage by weight: 0.16 to 0.20 percent of C, 0.20 to 0.40 percent of Si, 1.20 to 1.50 percent of Mn, less than or equal to 0.006 percent of P, less than or equal to 0.001 percent of S, 0.25 to 0.35 percent of Ni, 0.06 to 0.12 percent of Mo, 0.15 to 0.25 percent of Cr, 0.02 to 0.04 percent of Nb, 0.04 to 0.06 percent of V, 0.01 to 0.03 percent of Ti, 0.02 to 0.05 percent of Alt, less than or equal to 0.0005 percent of B, less than or equal to 0.0005 percent of Pb, less than or equal to 0.0005 percent of Sn, less than or equal to 0.0005 percent of As, less than or equal to 0.0005 percent of Sb, less than or equal to 0.0005 percent of Bi, less than or equal to 0.32 percent of Cr + Mo, the steel plate is of a mixed microstructure c