Ultrahigh-strength steel and manufacturing method for ultrahigh-strength steel continuous casting slab

The invention discloses ultrahigh-strength steel. The ultrahigh-strength steel comprises the following components of, by mass, 0.38%-0.42% of C, 1.40%-1.55% of Si, 0.75%-0.85% of Mn, 0-0.008% of P, 0-0.005% of S, 0.85%-0.95% of Cr, 0.37%-0.43% of Mo, 0.02%-0.04% of Nb, 1.05%-1.25% of Ni, 0.2%-0.3% of Cu, 0.009%-0.029% of Ti, and the balance Fe and inevitable impurities. The invention further discloses a manufacturing method for the ultrahigh-strength steel continuous casting slab. According to the ultrahigh-strength steel and the manufacturing method for the ultrahigh-strength steel continuouscasting slab, by designing reasonable smelting, pouring and heat treatment processes, the ultrahigh-strength steel continuous casting slab with the relatively high alloy content (greater than or equal to 5%) and the excellent surface quality can be produced. 本发明公开了一种超高强度钢，以质量百分比计，包含：0.38-0.42％的C、1.40-1.55％的Si、0.75-0.85％的Mn、0-0.008％的P、0-0.005％的S、0.85-0.95％的Cr、0.37-0.43％的Mo、0.02-0.04％的Nb、1.05-1.25％的Ni、0.2-0.3％的Cu、0.009-0.0