THICK PLATE HAVING HIGH STRENGTH AND TOUGHNESS AND METHOD OF MANUFACTURING THE SAME

摘要

A thick steel sheet with high strength and high toughness and a manufacturing method thereof are provided. The manufacturing method comprises: a step of heating a slab at a temperature range of 1100-1200°C; a step of rolling the slab at an accumulated reduction ratio of 30% or greater and at a temperature of Ar3 or higher; a step of performing accelerated cooling on the rolled slab by water cooling at a temperature range of 350-600°C and at a cooling rate of 3°C/sec or greater; and a step of performing air cooling on the slab, which was cooled by water cooling, to room temperature, wherein the slab comprises 0.04-0.10 wt% of C, 0.10-0.40 wt% of Si, 1.10-1.60 wt% of Mn, 0.01-0.05 wt% of Al, 0.005-0.03 wt% of Ti, 0.005-0.03 wt% of Nb, 0.02 wt% or less of P, 0.005 wt% or less of S, and remnants of Fe and other inevitable impurities.